Transcript
Study of 12 Lead ECG ST2360A
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ST2360A
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Study of 12 Lead ECG ST2360A Table of Contents Safety Instructions
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2.
Introduction
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3.
Features
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Technical Specifications
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Human Cardiovascular System
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Electrocardiogram (ECG/EKG)
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Standards of ECG Leads Configuration used for measurement
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Application Areas of 12 Lead ECG Diagnoses
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Increase in Wall Thickness or Size of Atria and Ventricles
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Operating Instructions
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Experiments
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Experiment 1 Study of Lead I of Standard Bipolar Lead Configuration
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Experiment 2 Study of Lead II of Standard Bipolar Lead Configuration
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Experiment 3 Study of Lead III of Standard Bipolar Lead Configuration
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Experiment 4 Study of aVR Lead of Standard Augmented Uni-polar Lead configuration
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Experiment 5 Study of aVL Lead of Standard Augmented Uni-polar Lead configuration
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Experiment 6 Study of aVF Lead of Standard Augmented Uni-polar Lead configuration
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Experiment 7 Study of Chest Lead V1 of Standard Uni-polar Lead configuration
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Experiment 8 Study of Chest Lead V2 of Standard Uni-polar Lead configuration
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Experiment 9 Study of Chest Lead V3 of Standard Uni-polar Lead configuration
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Experiment 10 Study of Chest Lead V4 of Standard Uni-polar Lead Configuration
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Experiment 11 Study of Chest Lead V5 of Standard Uni-polar Lead Configuration
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Experiment 12 Study of Chest Lead V6 of Standard Uni-polar Lead Configuration
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Glossary of Human Cardiovascular System Terms
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Frequently Asked Questions
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Warranty
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List of Accessories
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Safety Instructions Read the following safety instructions carefully before operating the instrument. To avoid any personal injury or damage to the instrument or any product connected to it. Do not operate the instrument if suspect any damage to it. The instrument should be serviced by qualified personnel only. For your safety: : Use only the mains cord designed for this instrument. Ensure that the mains cord is suitable for your country.
Ground the Instrument
: This instrument is grounded through the protective earth conductor of the mains cord. To avoid electric shock the grounding conductor must be connected to the earth ground. Before making connections to the input terminals, ensure that the instrument is properly grounded.
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Use proper Mains cord
: Use the fuse type and rating specified for this instrument.
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Use only the proper Fuse
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Observe Terminal Ratings : To avoid fire or shock hazards, observe all ratings and marks on the instrument.
Use in proper Atmosphere : Please refer to operating conditions given in the manual.
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Do not operate in wet / damp conditions.
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Do not operate atmosphere.
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Keep the product dust free, clean and dry.
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Introduction An Electrocardiogram (ECG or EKG, abbreviated from the German Elektrokardiogramm) is a graphical representation of an electrocardiograph, which records the electrical activity of the heart over time. Analysis of the various waves and normal vectors of depolarization and repolarization yields important diagnostic information. It is the Gold standard for the diagnosis of cardiac arrhythmias
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It guides therapy and risk stratification for patients with suspected acute myocardial infarction
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It helps detect electrolyte disturbances (e.g. hyperkalemia and hypokalemia)
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It allows for the detection of conduction abnormalities (e.g. right and left bundle branch block)
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ST2360A Study of 12 Lead ECG is designed in such a manner that it provides accurate measurement of all 12 Leads examination of heart signals including both Unipolar and Bipolar configurations. ST2360A illustrates the fundamentals of standard limbs (bipolar) and chest Leads (Unipolar) interpretation and rhythm recognition in an easy-to-use manner.
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ST2360A uses 10 electrodes lead cable for measurement of 12 Lead Real Time ECG. 12 lead examination of heart gives full information of the heart anatomy, physiology and Electrical conduction system. It has inbuilt touch-screen LCD screen which gives the accurate wave shapes of all the Leads. The abnormalities occurring in human cardiovascular system like Tachycardia (faster Heart-rate), Bradycardia (slower Heart-rate), Myocardial Infraction (insufficient blood supply), Atrial or Ventricular Hypertrophy (enlargement in the heart wall) Myocardial Ischemia (blood deficiency) and Carditis (inflammation in heart tissue) etc. are also studied by observing the real time wave pattern.
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Features Provides 12 leads real time amplified ECG output.
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Provides in-depth study of Standard Unipolar and Bipolar Leads Configuration for all ECG wave measurement in real time.
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Inbuilt touch screen 7.5” LCD for examining wave shapes and measurements.
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Provides on screen information about different types of heart diseases (Bradycardia & Tachycardia)
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Provides on screen information about leads connection and electrode placement on the patient body.
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On screen Amplitude and heart frequency calculation
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On screen Calculation of wave duration and wave interval
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Technical Specifications :
7.5” touch screen (320 x 240)
ECG Amplitude
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2Vpp
ECG Lead Cable
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Standard 10 Lead Cable
Electrode used
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Clamp & Suction cup electrode
Bipolar Leads Configuration
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Lead I, II & III
Unipolar Leads Configuration
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aVR, aVL, aVF, Chest Leads (V1-V6)
Power Supply
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230/110V +10%, 50/60Hz
Dimensions (mm)
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W 360 x D 260 x H 120
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2.5 Kg (approximately)
Weight
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LCD
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Figure 1
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Human Cardio-Vascular System The Anatomy of the Human Heart: The heart is basically a hollow muscular pump, which pushes the blood through out the body via the blood vessels. It is located between the lungs and slightly to the left of centre. The heart is an involuntary muscle that has approximately seventy to ninety contractions per minute during a restful state. It begins to pump early in the life of a fetus and will continue unceasingly until death. Heart Wall: The heart wall is divided into three layers Pericardium
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Myocardium
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Endocardium
Heart Chambers:
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The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called Atria and the lower two chambers are called Ventricles. Valves allow blood to flow in one direction between the chambers of the heart. The heart has four distinct chambers
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Right Atrium is the thin-walled area that receives the venous or "used" blood returning to the body by the veins.
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Right Ventricle is the "pump" area of the heart's right side. The atrium dumps the blood into the ventricle where it is then pumped out the pulmonary arteries and to the lungs.
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Left Atrium receives the oxygenated blood returning from the lungs.
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Left Ventricle has the thickest walls of all. It is from this chamber the blood is pumped out of the heart, into the aorta and out to the rest of the body.
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Heart Valves: 1.
Tricuspid valve is the one located at the entrance of the right ventricle. It prevents the blood from washing back into the right atrium.
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Pulmonary Semilunar valve is located between the right ventricle and the pulmonary artery.
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Mitral valve is made of very heavy cusps and is located at the entrance of the left ventricle. This is a powerful valve that closes as the left ventricle begins each of its contractions to ensure the oxygenated blood does not re-enter the left atrium.
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Aortic valve is located, as its name would imply, between the left ventricle's exit and the aorta itself.
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Even though the heart is split up into two distinct halves, these two must work together to function properly.
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Human Heart
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The Heart's Conduction System: There are four basic components to the heart's conduction system. 1.
Sinoatrial node (SA node)
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Inter-nodal fiber bundles
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Atrioventricular node (AV node)
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Atrioventricular bundle
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At the right top corner of the heart there is a special group of excitable cells, called Natural Pacemaker or Sinoatrial Node. This natural pacemaker generates electrical impulses spontaneously. At the lower part of the right atrium there is another mass of specialized group of cells called Atrioventricular Node. From the atrioventricular node a bundle of conducting fiber called Bundle of His, passes down to interventricular septum.
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A natural pacemaker generates electrical impulses at regular rate. To initiate the heartbeat the action potentials generated by the natural pacemaker or S.A. node gets propagated in all directions along the surface of both atria and atrioventricular node. This spreads through out the right and left atrium, their wall tissues and results into contraction of atria. Now the waveform reaches to the A.V. node through special nerve fiber which provides the delay in propagation so as to have proper timing between the pumping action of atrium and ventricles. During the delay time the atria completes their contraction forcing blood into ventricles in order to complete their filling. At this point A.V. node initiates an impulse that gets propagated into the ventricles throughout bundles of his then into left and right bundle branch and further into purkinje fibers causing contraction of both the ventricles and forcing blood into lungs and the whole body. During the contraction of ventricles the atria complete their filling and to initiate the next heart beat a pacemaker generates another electrical impulse.
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With the natural pacemaker providing the impulse, the rate of contraction of the heart is maintains and controlled. Normally this action occurs for 60-100 times in a minute, when additional blood is required, the flow must be increased. This is achieved by generating the impulse at faster rate by natural pacemaker.
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Electrocardiogram (ECG / EKG) As the heart undergoes depolarization and repolarization, the electrical currents that are generated and spread not only within the heart, but also through out the body. This electrical activity generated by the heart can be measured by an array of electrodes placed on the body surface. The recorded tracing is called an Electrocardiogram (ECG or EKG). A "typical" ECG tracing is shown below. The different waves that comprise the ECG represent the sequence of depolarization and repolarization of the atria and ventricles. The P wave represents the wave of depolarization that spreads from the SA node throughout the atria, and is usually 0.08 to 0.1 seconds (80-100 ms) in duration.
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Standard ECG Wave
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The QRS complex represents ventricular depolarization. The duration of the QRS complex is normally 0.06 to 0.1 seconds. This relatively short duration indicates that ventricular depolarization normally occurs very rapidly. The T wave represents ventricular repolarization and is longer in duration than depolarization (i.e., conduction of the repolarization wave is slower than the wave of depolarization). Typically the total time required for one complete cycle of the heart electrical activity ranges from approximately 0.4 to 0.6 second while 0.8 seconds is the standard value of one complete heart cycle. The remaining 0.2 second is lighter including U wave or not. This U wave represents the state of heart when all four chambers of heart receive the blood generally this wave is not present in the normal ECG graph.
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A healthy ECG shows a normal sinus rhythm. This is when each depolarization of the cardiac conduction system creates a P wave, followed by a QRS complex, followed by a T wave. During a normal sinus rhythm, the atria are contracting first (around the time of the P wave), and the ventricles contract second (around the time of the QRS complex). Ventricular relaxation occurs around the time of the T wave.
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The Heart-rate is a rate at which the heart beats per minute. It is controlled by the frequency at which the natural pacemaker generates electrical pulses. However cardiac and vagus nerves of the sympathetic systems and parasympathetic systems causes the heart-rate to increase or decrease respectively according to body requirements. When measured using heart-sounds or ECG it is called heart-rate.
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A person's physiological size largely determines a person's resting heart rate. The bigger a person is, the slower the heart rate. A newborn baby's heart beats about 120 times per minute. The typical rate for adults is 72 beats per minute. But doctors consider resting rates from 60 to 100 beats per minute within the normal range (normal sinus rhythm).
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A sinus rhythm slower than normal is called Bradycardia. A sinus rhythm higher than normal is called Tachycardia.
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Standards of ECG Leads Configuration used for measurement The voltage generated by the pumping action of the heart is actually a vector whose magnitude, as well as spatial orientation, changes with time. Because the ECG signal is measured from electrodes applied to the surface of the body, the waveform of this signal is very dependent on the placement of electrodes. To record the ECG pattern of a subject (human body) it is necessary to apply ECG metal electrodes to the patient's limbs in special formats called Leads, on each Arm and Leg, and six electrodes are placed at defined locations on the chest. These electrode Leads are connected to a device that measures potential differences between selected electrodes to produce the characteristic electro-cardio-graphic tracings. Limb Leads (Bipolar)
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Augmented Limb Leads (Unipolar)
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Chest Leads (Unipolar)
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Limb Leads (Bipolar):
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Augmented Limb Leads (Unipolar):
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Limb Lead (Bipolar) Configuration
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Chest Leads (Unipolar): The chest ECG Leads are considered as the pre-cordial, unipolar chest leads. There are six positive electrodes placed on the surface of the chest over the heart in order to record electrical activity in a plane perpendicular to the frontal plane (see Figure 8). These six Leads are named V1–V6. The rules of interpretation are the same as for the limb Leads. For example, a wave of depolarization travelling towards a ventricular electrode on the chest surface will elicit a positive deflection. In chest Leads positive electrode (yellow) placed on chest, negative electrode(Red) is placed on central terminal of Left Arm , Right Arm, Left Leg and reference Electrode(Black) is placed on Right Leg of subject(Human body). Position of electrode for pericardial Leads: V1: Right sternal margin at 4th intercoastal space (ICS)
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V2: Left sternal margin at 4th ICS V4: Intersection of 5th ICS and left mid-clavicular line
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V3: midway between V2 and V4
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V5: Intersection of left anterior auxiliary line with a horizontal line through V4
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V6: Intersection of left mid-auxiliary line with a horizontal line through V4 and V5
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Figure 9
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Einthoven Triangle: For defining the bipolar Leads Einthoven postulated that at any given state of the cardiac cycle electrical axis of the heart can be represented as a two dimensional vector, he proposed that the electric field of the heart could be represented by diagrammatically as a triangle. With the heart ideally located at the centre. The side of the triangle represents the line along which the three projection of the ECG vector are measured. It was shown that the instantaneous voltage measured from any of the limb Lead position is approximately equal to the algebraic sum of the other two or that the vector sum of the projections on all three lines is equal to zero.
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Electrical Axis of Heart: The heart's electrical axis refers to the general direction of the heart's depolarization wave front (or mean electrical vector) in the frontal plane. It is usually oriented in a right shoulder to left Leg direction, which corresponds to the left inferior quadrant of the hex-axial reference system, although -30o to +90o is considered to be normal. •
Left axis deviation: (-30o to -90o) may indicate left anterior fascicular block or Q waves from inferior myocardial infraction.
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Right axis deviation: (+90o to +180o) may indicate left posterior fascicular block, Q waves from high lateral myocardial infraction or a right ventricular strain pattern.
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ECG Electrical Axis (The Mean Electrical Axis):
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The mean electrical axis will be the sum of all of the mean electrical vectors. The mean electrical axis corresponds to the axis that is perpendicular to the Lead axis that has the smallest net QRS amplitude (net amplitude = positive minus negative deflection voltages of QRS complex
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To determine the mean electrical axis from the ECG, find the Lead axis that has a biphasic (equally positive and negative QRS deflections - i.e. no net deflection) and then find the Lead axis that is perpendicular (90º) to the biphasic Lead and that has a positive net deflection. In the six limb Leads in the example below, aVL is biphasic. The positive perpendicular axis to aVL is +60º. Therefore, the mean electrical axis is +60º, which is normal.
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Normal electrical axis of heart
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Application Areas of 12 Lead ECG Diagnoses
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The main applications of the ECG to Cardiological diagnosis include the following
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The electric axis of the heart
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Heart rate monitoring
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Arrhythmias
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Supraventricular arrhythmias
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Ventricular arrhythmias
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Disorders in the activation sequence
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Atrioventricular conduction defects (blocks) Bundle-branch block
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Wolff-Parkinson-White syndrome
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Increase in wall thickness or size of the atria and ventricles Atrial enlargement (hypertrophy)
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Ventricular enlargement (hypertrophy
Myocardial Ischemia and Infarction
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Drug effect •
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Electrolyte imbalance •
Potassium
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Pacemaker monitoring
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Cardiac Rhythm Diagnosis: Cardiac rhythms may be divided into two categories: 1.
Supraventricular (above the ventricles)
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Ventricular rhythms.
The origin of Supraventricular rhythms (a single pulse or a continuous rhythm) is in the atria or AV junction, and the activation proceeds to the ventricles along the conduction system in a normal way. Normal sinus rhythm
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Normal sinus rhythm is the rhythm of a healthy normal heart, where the sinus node triggers the cardiac activation. This is easily diagnosed by noting that the three deflections, P-QRS-T, follow in this order and are differentiable. The sinus rhythm is normal if its frequency is between 60 and 100/Min. Impulses originate at S-A node at normal rate
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Normal sinus rhythm
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Sinus Bradycardia
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Sinus rhythm less than 60/ min are called Sinus Bradycardia. This may be a consequence of increased vagal or parasympathetic tone. Impulses originate at S-A node at slow rate
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Sinus Bradycardia Figure 16
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Sinus Tachycardia Sinus rhythm higher than 100/ min is called Sinus Tachycardia. It occurs most often as a physiological response to physical exercise or psychical stress, but may also result from congestive heart failure. Impulses originate at S-A node at rapid rate
Sinus Arrhythmia
Sinus Tachycardia Figure 17
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All complexes normal, evenly spaced Rate > 100/ Min
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If the sinus rhythm is irregular such that the longest PP- or RR-interval exceeds the shortest interval by 0.16 s, the situation is called sinus arrhythmia. This situation is very common in all age groups. This arrhythmia is so common in young people that it is not considered a heart disease. One origin for the sinus arrhythmia may be the vagus nerve which mediates respiration as well as heart rhythm. The nerve is active during respiration and, through its effect on the sinus node, causes an increase in heart rate during inspiration and a decrease during expiration. The effect is particularly pronounced in children.
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Note, that in all of the preceding rhythms the length of the cardiac activation cycle (the P-QRS-T-waves together) is less than directly proportional to the PP-time. The main time interval change is between the T-wave and the next P-wave. This is easy to understand since the pulse rate of the sinus node is controlled mainly by factors external to the heart while the cardiac conduction velocity is controlled by conditions internal to the heart.
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ST2360A Impulses originate at S-A node at rapid rate
All complexes normal, rhythm is irregular Longest R-R interval exceeds shortest > 0.16 s
Sinus arrhythmia Figure 18
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Non-sinus Atrial rhythm
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Atrial Flutter
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The origin of atrial contraction may be located somewhere else in the atria other than the sinus node. If it is located close to the AV node, the atrial depolarization occurs in a direction that is opposite the normal one. An obvious consequence is that in the ECG the P-wave has opposite polarity.
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When the heart rate is sufficiently elevated so that the iso-electric interval between the end of T and beginning of P disappears, the arrhythmia is called atrial flutter. The origin is also believed to involve a reentrant atrial pathway. The frequency of these fluctuations is between 220 and 300/min. The AV-node and, thereafter, the ventricles are generally activated by every second or every third atrial impulse (2:1 or 3:1 heart block). Impulses travel in circular course in atria
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Atrial flutter Figure 19
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Atrial Fibrillation The activation in the atria may also be fully irregular and chaotic, producing irregular fluctuations in the baseline. A consequence is that the ventricular rate is rapid and irregular, though the QRS contour is usually normal. Atrial fibrillation occurs as a consequence of rheumatic disease, atherosclerotic disease, hyperthyroidism, and pericarditis (It may also occur in healthy subjects as a result of strong sympathetic activation.) Impulses have chaotic, random pathways in atria
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Junctional Rhythm
Figure 20
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If the heart rate is slow (40-55/Min.), the QRS-complex is normal, the P-waves are possibly not seen, and then the origin of the cardiac rhythm is in the AV node. Because the origin is in the junction between atria and ventricles, this is called Junctional rhythm. Therefore, the activation of the atria occurs retrograde (i.e., in the opposite direction). Depending on whether the AV-nodal impulse reaches the atria before, simultaneously, or after the ventricles, an opposite polarity P-wave will be produced before, during, or after the QRS-complex, respectively. In the second case the P-wave will be superimposed on the QRS-complex and will not be seen.
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Impulses originate at AV node with retrograde and antegrade direction
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Junctional rhythm Figure 21
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Ventricular Arrhythmias: In ventricular arrhythmias ventricular activation does not originate from the AV node and/or does not proceed in the ventricles in a normal way. If the activation proceeds to the ventricles along the conduction system, the inner walls of the ventricles are activated almost simultaneously and the activation front proceeds mainly radially toward the outer walls. As a result, the QRS-complex is of relatively short duration. If the ventricular conduction system is broken or the ventricular activation starts far from the AV node, it takes a longer time for the activation front to proceed throughout the ventricular mass. The criterion for normal ventricular activation is a QRS-interval shorter than 0.1 s. A QRS-interval lasting longer than 0.1 s indicates abnormal ventricular activation. Premature ventricular contraction
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A premature ventricular contraction is one that occurs abnormally early. If its origin is in the atrium or in the AV node, it has a Supraventricular origin. The complex produced by this Supraventricular arrhythmia lasts less than 0.1 s. If the origin is in the ventricular muscle, the QRS-complex has a very abnormal form and lasts longer than 0.1 s. Usually the P-wave is not associated with it.
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A single impulse originates at right ventricle
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Time interval between normal R peaks is a multiple of R-R intervals
Premature ventricular contraction
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Idioventricular Rhythm If the ventricles are continuously activated by a ventricular focus whose rhythm is under 40/Min, the rhythm is called idioventricular rhythm. The ventricular activity may also be formed from short (less than 20 s) bursts of ventricular activity at higher rates (between 40 and 120/Min). This situation is called accelerated idioventricular rhythm. The origin of the ventricular rhythm may be located by observing the polarity in various leads. The direction of the activation front is, of course, the direction of the lead vector in that lead where the deflection is most positive. The origin of the activation is, of course, on the opposite side of the heart when one is looking from this electrode. Ventricular Tachycardia
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A rhythm of ventricular origin may also be a consequence of a slower conduction in ischemic ventricular muscle that leads to circular activation (re-entry). The result is activation of the ventricular muscle at a high rate (over 120/Min.), causing rapid, bizarre, and wide QRS-complexes; the arrhythmia is called ventricular tachycardia. As noted, ventricular tachycardia is often a consequence of ischemia and myocardial infarction. Impulse originate at ventricular pacemaker
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Ventricular Tachycardia
Figure 23
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Ventricular Fibrillation When ventricular depolarization occurs chaotically, the situation is called ventricular fibrillation. This is reflected in the ECG, which demonstrates coarse irregular undulations without QRS-complexes. The cause of fibrillation is the establishment of multiple re-entry loops usually involving diseased heart muscle. In this arrhythmia the contraction of the ventricular muscle is also irregular and is ineffective at pumping blood. The lack of blood circulation leads to almost immediate loss of consciousness and death within minutes. The ventricular fibrillation may be stopped with an external defibrillator pulse and appropriate medication. Chaotic ventricular depolarization
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Ventricular Fibrillation
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Pacer Rhythm
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A ventricular rhythm originating from a cardiac pacemaker is associated with wide QRS-complexes because the pacing electrode is (usually) located in the right ventricle and activation does not involve the conduction system. In pacer rhythm the ventricular contraction is usually preceded by a clearly visible pacer impulse spike. The pacer rhythm is usually set to 72/min. Impulses originate at trans-venous pacemaker
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Pacer Rhythm Figure 25 Disorders in the activation sequence
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Atrioventricular Conduction Variations: As discussed earlier, if the P-waves always precede the QRS-complex with a PRinterval of 0.12-0.2 s, the AV conduction is normal and a sinus rhythm is diagnosed. If the PR-interval is fixed but shorter than normal, either the origin of the impulse is closer to the ventricles or the atrioventricular conduction is utilizing an (abnormal) bypass tract leading to pre-excitation of the ventricles. The latter is called the WolffParkinson-White syndrome and is discussed below. The PR-interval may also be variable, such as in a wandering atrial pacemaker and multifocal atrial tachycardia. First-degree Atrioventricular Block: When the P-wave always precedes the QRS-complex but the PR-interval is prolonged over 0.2 s, first-degree atrioventricular block is diagnosed.
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Atrioventricular conduction lengthened
P-wave precedes each QRS-complex but PR-interval is > 0.2 s
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First-degree atrioventricular block
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Second-degree Atrioventricular Block:
Figure 26
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If the PQ-interval is longer than normal and the QRS-complex sometimes does not follow the P-wave, the atrioventricular block is of second-degree. If the PR-interval progressively lengthens, leading finally to the drop out of a QRS-complex, the second degree block is called a Wenkebach phenomenon. Sudden dropped QRS-complex
Intermittently skipped ventricular beat
Second-degree atrioventricular block Figure 27
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ST2360A
Third-degree Atrioventricular Block: Complete lack of synchronism between the P-wave and the QRS-complex is diagnosed as third-degree (or total) atrioventricular block. The conduction system defect in third degree AV-block may arise at different locations such as: Over the AV-node, in the bundle of Hiss Bilaterally in the upper part of both bundle branches Tri-fascicularly, located still lower, so that it exists in the right bundlebranch and in the two fascicles of the left bundle-branch. Impulses originate at AV node and proceed to ventricles Atrial and ventricular activities are not synchronous
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P-P interval normal and constant, QRS complexes normal, rate constant, 20 55 /Min
Third-degree atrioventricular block
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Bundle-Branch Block:
Figure 27
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Bundle-branch block denotes a conduction defect in either of the bundle-branches or in either fascicle of the left bundle-branch. If the two bundle-branches exhibit a block simultaneously, the progress of activation from the atria to the ventricles is completely inhibited; this is regarded as third-degree atrioventricular block. The consequence of left or right bundle-branch block is that activation of the ventricle must await initiation by the opposite ventricle. After this, activation proceeds entirely on a cell-to-cell basis. The absence of involvement of the conduction system, which initiates early activity of many sites, results in a much slower activation process along normal pathways. The consequence is manifest in bizarre shaped QRS-complexes of abnormally long duration.
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ST2360A
Right Bundle-Branch Block (RBBB): If the right bundle-branch is defective so that the electrical impulse cannot travel through it to the right ventricle, activation reaches the right ventricle by proceeding from the left ventricle. It then travels through the septal and right ventricular muscle mass. This progress is, of course, slower than that through the conduction system and leads to a QRS-complex wider than 0.1 s. Usually the duration criterion for the QRScomplex in right bundle-branch block (RBBB) as well as for the left bundle- branch block (LBBB) is >0.12 s.
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With normal activation the electrical forces of the right ventricle are partially concealed by the larger sources arising from the activation of the left ventricle. In right bundle-branch block (RBBB), activation of the right ventricle is so much delayed, that it can be seen following the activation of the left ventricle. (Activation of the left ventricle takes place normally.) RBBB causes an abnormal terminal QRSvector that is directed to the right ventricle (i.e., rightward and anterior). This is seen in the ECG as a broad terminal S-wave in lead I. Another typical manifestation is seen in lead V1 as a double R-wave. This is named an RSR'-complex.
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ST2360A
QRS duration greater than 0.12 s Wide S wave in leads I, V5 and V6
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Right bundle-branch block
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Scientech Technologies Pvt. Ltd.
Figure 28
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ST2360A
Left Bundle-Branch Block (LBBB): The situation in left bundle-branch block (LBBB) is similar, but activation proceeds in a direction opposite to RBBB. Again the duration criterion for complete block is 0.12 s or more for the QRS-complex. Because the activation wave front travels in more or less the normal direction in LBBB, the signals' polarities are generally normal. However, because of the abnormal sites of initiation of the left ventricular activation front and the presence of normal right ventricular activation the outcome is complex and the electric heart vector makes a slower and larger loop to the left and is seen as a broad and tall R-wave, usually in leads I, aVL, V5, or V6. QRS duration greater than 0.12 s Wide S wave in leads V1 and V2, wide R wave in V5 and V6
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/ed Left bundle-branch block Figure 29
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ST2360A
Wolff-Parkinson-White syndrome: One cause for a broad QRS-complex that exceeds over 0.12s may be the WolffParkinson-White syndrome (WPW syndrome). In the WPW syndrome the QRScomplex initially exhibits an early upstroke called the delta wave. The interval from the P-wave to the R spike is normal, but the early ventricular excitation forming the delta wave shortens the PQ-time. The cause of the WPW syndrome is the passage of activation from the atrium directly to the ventricular muscle via an abnormal route, called the bundle of Kent, which bypasses the AV junctions. This activates part of the ventricular muscle before normal activation reaches it via the conduction system (after a delay in the AV junction). The process is called pre-excitation, and the resulting ECG depends on the specific location of the accessory pathway.
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ST2360A
Increase in Wall Thickness or Size of Atria and Ventricles Atrial and ventricular muscles react to physical stress in the same way as skeletal muscles: The muscles enlarge with increased amount of exercise. The extra tension may arise as a result of increased pressure load or volume load. Pressure overload is a consequence of increased resistance in the outflow tract of the particular compartment concerned (e.g., aortic stenosis). Volume overload means that either the outflow valve or the inflow valve of the compartment is incompetent, thus necessitating a larger stroke volume as compensation for the regurgitate backflow. The increase in the atrial or ventricular size is called atrial or ventricular enlargement. The increase of the atrial or ventricular wall thickness is called atrial or ventricular hypertrophy.
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Atrial hypertrophy
(1)Right atrial hypertrophy
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Right atrial hypertrophy is a consequence of right atrial overload. This may be a result of tricuspid valve disease (stenosis or insufficiency), pulmonary valve disease, or pulmonary hypertension (increased pulmonary blood pressure). The latter is most commonly a consequence of chronic obstructive pulmonary disease or pulmonary emboli.
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(2)Left atrial hypertrophy
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In right atrial hypertrophy the electrical force due to the enlarged right atrium is larger. This electrical force is oriented mainly in the direction of lead II but also in leads aVF and III. In all of these leads an unusually large (i.e., 0.25 mV) P-wave is seen.
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Left atrial hypertrophy is a consequence of left atrial overload. This may be a result of mitral valve disease (stenosis or insufficiency), aortic valve disease, or hypertension in the systemic circulation. In left atrial hypertrophy the electrical impulse due to the enlarged left atrium is strengthened. This electrical impulse is directed mainly along lead I or opposite to the direction of lead V1. Because the atrial activation starts from the right atrium, the aforementioned left atrial activation is seen later, and therefore, the P-wave includes two phases. In lead I these phases have the same polarities and in lead V1 the opposite polarities. This typical P-wave form is called the mitral P-wave. The specific diagnostic criterion for left atrial hypertrophy is the terminal portion of the P-wave in V1, having duration 0.04 s and negative amplitude 0.1 mV.
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ST2360A
Right Atrial Hypertrophy
Left Atrial Hypertrophy
Tall, peaked P wave in leads I and II
Wide, notched P wave in lead II Dysphasic P wave in V1
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/ed Atrial hypertrophy Figure 30
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ST2360A
Ventricular hypertrophy: (1)Right ventricular hypertrophy: Right ventricular hypertrophy is a consequence of right ventricular overload. This is caused by pulmonary valve stenosis, tricuspid insufficiency, or pulmonary hypertension (see above). Also many congenital cardiac abnormalities, such as a ventricular septal defect, may cause right ventricular overload. Right ventricular hypertrophy increases the ventricular electrical forces directed to the right ventricle that is, to the right and front. This is seen in lead V1 as a tall R-wave of 0.7 mV. Large R wave in leads V1 and V3 ,Large S wave in leads V6 and V5
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/ed Right ventricular hypertrophy Figure 31
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ST2360A
(2)Left ventricular hypertrophy: Left ventricular hypertrophy is a consequence of left ventricular overload. It arises from mitral valve disease, aortic valve disease, or systemic hypertension. Left ventricular hypertrophy may also be a consequence of obstructive hypertrophic cardiomyopathy, which is a sickness of the cardiac muscle cells. Left ventricular hypertrophy increases the ventricular electric forces directed to the left ventricle - that is, to the left and posterior. Evidence of this is seen in lead I as a tall R-wave and in lead III as a tall S-wave (>2.5mV). Also a tall S-wave is seen in pre-cordial leads V1 and V2 and a tall R-wave in leads V5 and V6, (>3.5mV). Large S wave in leads V1 and V2,Large R wave in leads V6 and V5
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/ed Left ventricular hypertrophy Figure 32
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ST2360A
Myocardial Ischemia and Infarction: If a coronary artery is occluded, the transport of oxygen to the cardiac muscle is decreased, causing an oxygen debt in the muscle, which is called ischemia. Ischemia causes changes in the resting potential and in the repolarization of the muscle cells, which is seen as changes in the T-wave. If the oxygen transport is terminated in a certain area, the heart muscle dies in that region. This is called an infarction. An infarct area is electrically silent since it has lost its excitability. According to the solid angle theorem (Section 11.2.2) the loss of this outward dipole is equivalent to an electrical force pointing inward. With this principle it is possible to locate the infarction. (Of course, the infarct region also affects the activation sequence and the volume conductor so the outcome is more complicated.)
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/ed Myocardial ischemia and infarction Figure 33
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ST2360A
Operating Instructions While studying different Leads Configuration, the connections should be correct according to standard Leads Configuration for obtaining the correct waveform.
2.
For getting the accurate wave shape patient must be at rest and lay on the bench.
3.
Place all the electrodes over the body of the patient (Wrist, legs and Chest) before measurement.
4.
If patient is in sitting or standing position then because of motion artifacts there will be lot of disturbance into the signal of interest.
5.
Switch on the power supply only after connecting the Electrode lead cable to the patient.
6.
During measurement of ECG, patient should be at some distance from any mains power source to avoid noise problem.
7.
Do not talk or laugh during measurement as it will increase the level of noise.
8.
Do not take deep or slow breath always take normal breath during measurement to avoid motion artifacts.
9.
Switch off your mobile phones, pager or any electronic battery operated device during measurement. It is also dangerous for the heart patient.
10.
Place the electrode very carefully over chest at predefined position of ribs.
11.
Shorting between electrodes will result incorrect wave shape because of shorting of electrical voltages of heart over chest.
12.
Use the stylus for operating the touch screen for better accuracy of touch.
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ST2360A
Experiment 1 Objective: Study of Lead I of standard Bipolar Lead Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to
4.
Switch ‘ON’ the ST2360A by Power switch.
5.
Select the Lead I by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Lead I configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Lead I configuration is observed in proper shape and frequency.
2.
Different parameters of heart are lies in normal range.
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ST2360A
Experiment 2 Objective: Study of Lead II of standard Bipolar Lead Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Lead II by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Lead II configuration on LCD screen of ST2360A.
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Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Lead II configuration is observed in proper shape and frequency.
2.
Different parameters of heart are lies in normal range.
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Scientech Technologies Pvt. Ltd.
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ST2360A
Experiment 3 Objective: Study of Lead III of standard Bipolar Lead Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Lead III by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Lead III configuration on LCD screen of ST2360A
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Lead III configuration is observed in proper shape and frequency.
2.
Amplitude of wave is small because of weak electrical vector in this direction
3.
Different parameters of heart are lies in normal range.
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ST2360A
Experiment 4 Objective: Study of aVR Lead of standard Unipolar Leads Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the aVR by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of aVR configuration on LCD screen of ST2360A.
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Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard aVR configuration is observed in proper shape and frequency.
2.
This is the only inverted wave in ECG wave analysis
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Different parameters of heart are lies in normal range.
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ST2360A
Experiment 5 Objective: Study of aVL Lead of standard unipolar limb Leads Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the aVL by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of aVL configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard aVL configuration is observed in proper shape and frequency.
2.
Different parameters of heart are lies in normal range.
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Scientech Technologies Pvt. Ltd.
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ST2360A
Experiment 6 Objective: Study of aVF Lead of standard unipolar Leads Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the aVF by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of aVF configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard aVF configuration is observed in proper shape and frequency.
2.
Different parameters of heart are lies in normal range.
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ST2360A
Experiment 7 Objective: Study of Chest Lead V1 of standard unipolar Leads Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the Study of ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Chest Lead V1 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Chest Lead V1 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V1 configuration is observed in proper shape and frequency.
2.
Amplitude of the wave is high because of higher electrical potential of heart in this region
3.
Different parameters of heart are lies in normal range.
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Scientech Technologies Pvt. Ltd.
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ST2360A
Experiment 8 Objective: Study of Chest Lead V2 of standard unipolar Lead Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the by Power switch.
5.
Select the Chest Lead V2 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Chest Lead V2 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V2 configuration is observed in proper shape and frequency.
2.
Negative part of the wave are going to shift towards positive due to RS transition takes place
3.
Different parameters of heart are lies in normal range.
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ST2360A
Experiment 9 Objective: Study of Chest Lead V3 of standard unipolar Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Chest Lead V3 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Chest Lead V3 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V3 configuration is observed in proper shape and frequency.
2.
More RS transition takes place in this wave pattern
3.
Different parameters of heart are lies in normal range.
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ST2360A
Experiment 10 Objective: Study of Chest Lead V4 of standard unipolar Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Chest Lead V4 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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Observe the real time ECG waveform of Chest Lead V4 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V4 configuration is observed in proper shape and frequency.
2.
RS transition is completed and wave pattern is shifted more towards positive direction
3.
Different parameters of heart are lies in normal range.
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Scientech Technologies Pvt. Ltd.
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ST2360A
Experiment 11 Objective: Study of Chest Lead V5 of standard Unipolar Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Chest Lead V5 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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1.
Observe the real time ECG waveform of Chest Lead V5 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V5 configuration is observed in proper shape and frequency.
2.
Amplitude of wave is reduced again and because of less electrical activity of electrical vector in this direction
3.
Different parameters of heart are lies in normal range.
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Scientech Technologies Pvt. Ltd.
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ST2360A
Experiment 12 Objective: Study of Chest Lead V6 of standard Unipolar Configuration Equipments Needed: 1.
ST2360A Study of 12 Lead ECG
2.
ECG Cable
Procedure: Connect one end of the power supply to the ST2360A while other end to the AC mains.
2.
Connect the electrode leads cable to the patient.
3.
Connect the electrode lead connector to ST2360A.
4.
Switch ‘On’ the ST2360A by Power switch.
5.
Select the Chest Lead V6 by touching the screen with the help of stylus.
6.
Touch on the signal with the help of stylus for observing the signal.
Observation:
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1.
Observe the real time ECG waveform of Chest Lead V6 configuration on LCD screen of ST2360A.
2.
Calculate different parameters on screen using stylus.
Conclusion:
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Real time ECG waveform of Standard Chest Lead V6 configuration is observed in proper shape and frequency.
2.
Different parameters of heart are lies in normal range.
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ST2360A
Glossary of Human Cardiovascular System Terms Artery: A muscular blood vessel that carries blood away from the heart. Arrhythmia: Is an abnormal heart rhythm. Atrium: One of the chambers of the heart that receives blood directly from a vein. Bradycardia: When the heart-rate less than the normal heart-rate rhythm. Circulatory System: The system of the body responsible for internal transport. It composed of the heart, blood vessels, lymphatic vessels, lymph, and the blood. Cardiology: Is the branch of medicine that deals with the diagnosis and treatment of disorders of the heart.
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Diastole: Pronounced dy AS tuh lee is the period of heart activity when the ventricles relax.
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Diastolic Pressure: The decreased pressure due to the relaxation of the ventricles is called diastolic pressure.
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Electrocardiograph (ECG): Is an instrument used to detect heart damage or diagnose heart disorders.
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Heart: The muscular organ composed of cardiac muscle that is responsible for pumping blood throughout the body.
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Normal Sinus Rhythm: Normal pumping action of heart generates 60 -100 heartbeats per minute.
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Septum: The wall dividing the two ventricles.
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Systole: Is the period of heart activity when the ventricles contract.
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Systolic Pressure: The increased pressure due to the contraction of the ventricles is called systolic pressure. Tachycardia: When the heart-rate exceeds than the normal heart-rate rhythm.
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Ventricle: One of the muscular chambers of the heart that is responsible for pumping blood from the heart into the arteries.
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ST2360A
Frequently Asked Questions 1.
What is the Anatomy of the human heart? The heart is basically a hollow muscular pump, which pushes the blood through out the body via the blood vessels. It is located between the lungs and slightly to the left of centre
2.
How many does contractions heart have? The heart is an involuntary muscle that has approximately seventy to ninety contractions per minute during a restful state. It begins to pump early in the life of a fetus and will continue unceasingly until death.
3.
In how many layers heart wall is divided, name them? The heart wall is divided into three layers:
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Pericardium
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Myocardium
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Endocardium
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How chamber is sub divided?
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The heart is divided by a partition or septum into two halves. The halves are in turn divided into chambers. The upper two chambers of the heart are called atria and the lower two chambers are called ventricles. How many chambers does heart have?
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The heart has four distinct chambers.
Right atrium is the thin-walled area that receives the venous or "used" blood returning to the body by the veins.
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Right ventricle is the "pump" area of the heart's right side. The atrium dumps the blood into the ventricle where it is then pumped out the pulmonary arteries and to the lungs.
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Left atrium receives the oxygenated blood returning from the lungs.
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Left ventricle has the thickest walls of all. It is from this chamber the blood is pumped out of the heart, into the aorta and out to the rest of the body.
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ST2360A
6.
How many types of heart valves are there? There are four types of heart valves which are as follows: Tricuspid valve: is the one located at the entrance of the right ventricle. It prevents the blood from washing back into the right atrium.
•
Pulmonary semi lunar valve: is located between the right ventricle and the pulmonary artery.
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Mitral valve: is made of very heavy cusps and is located at the entrance of the left ventricle. This is a powerful valve that closes as the left ventricle begins each of its contractions to ensure the oxygenated blood doesn't reenter the left atrium.
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Aortic valve: is located, as its name would imply, between the left ventricle's exit and the aorta itself.
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How right ventricle and left ventricle works?
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As the right ventricle contracts and sends blood to the lungs, the left ventricle contracts and squeezes blood out to the body. What is systole and diastole?
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Systole occurs when the ventricles contract, and diastole when they relax. One complete contraction and relaxation of the heart muscle makes up one heartbeat.
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9.
How many components heart conduction system have?
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Inter-nodal fiber bundles
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Atrioventricular node (AV node)
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Atrioventricular bundle
What is the function of natural pacemaker?
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Sino atrial node (SA node)
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10.
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There are four basic components to the heart's conduction system.
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A natural pacemaker generates electrical impulses at regular rate. To initiate the heartbeat the action potentials generated by the natural pacemaker or S.A. node gets propagated in all directions along the surface of both atria and atrioventricular node. 11.
What is the full form of ECG? Electrocardiogram
12.
How the electrical activity of heart can be sensed? This electrical activity generated by the heart can be measured by an array of electrodes placed on the body surface.
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13.
What P wave represents? The P wave represents the wave of depolarization that spreads from the SA node throughout the atria, and is usually 0.08 to 0.1 seconds (80-100 ms) in duration.
14.
What QRS complex represents? The QRS complex represents ventricular depolarization. The duration of the QRS complex is normally 0.06 to 0.1 seconds. This relatively short duration indicates that ventricular depolarization normally occurs very rapidly.
15.
What T wave represents? The T wave represents ventricular repolarization and is longer in duration than depolarization (i.e., conduction of the repolarization wave is slower than the wave of depolarization).
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16.
How much time period is required to complete one cycle by the heart?
Define heart rate?
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The total time required for one complete cycle of the heart electrical activity ranges from approximately 0.4 to 0.6 second. The Heart-rate is a rate at which the heart beats per minute.
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How the heart rate is controlled?
What is the heart rate for various human beings?
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It is controlled by the frequency at which the natural pacemaker generates electrical pulses.
To measure the ECG signals where the electrodes are placed on human body?
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The bigger a person is, the slower the heart rate. A newborn baby's heart beats about 120 times per minute. The typical rate for adults is 72 beats per minute. But doctors consider resting rates from 60 to 100 beats per minute within the normal range.
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To record the ECG pattern of a subject (human body) it is necessary to apply ECG metal electrodes to the patient's limbs in special formats called leads, on each arm and leg, and six electrodes are placed at defined locations on the chest. 21.
How electrical signals are generated through the heart? As the heart undergoes depolarization and repolarization, the electrical currents that are generated and spread not only within the heart, but also through out the body.
22.
How the electrical current is measured from the heart? The electrical activity generated by the heart can be measured by an array of electrodes placed on the body surface.
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23.
How different waves are generated? The different waves that comprise the ECG represent the sequence of depolarization and repolarization of the atria and ventricles.
24.
What ‘P’ wave represent? The ‘P’ wave represents the wave of depolarization that spreads from the SA node throughout the atria.
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What is the duration of ‘P’ wave? The duration is usually of 0.08 to 0.1 seconds (80-100 ms).
26.
What ‘QRS’ complex represents? The QRS complex represents ventricular depolarization.
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What is the duration of ‘QRS’ wave? The duration of the QRS complex is normally 0.06 to 0.1 seconds.
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What short duration indicates in ‘QRS’ wave?
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The relative short duration indicates that ventricular depolarization normally occurs very rapidly.
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What ‘T’ wave represents?
What is the duration of ‘T’ wave?
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The T wave represents ventricular repolarization and is longer in duration than depolarization.
What is the standard value of one complete cycle for ‘T’ wave?
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Typically the total time required for one complete cycle of the heart electrical activity ranges from approximately 0.4 to 0.6 second. 0.8 seconds is the standard value of one complete heart cycle. What ‘T’ wave represents?
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32.
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This U wave represents the state of heart when all four chambers of heart receive the blood generally this wave is not present in the normal ECG graph. 33.
Which type of activity is held during ‘P’,’QRS’ and ‘T’ wave? During a normal sinus rhythm, the atria are contracting first (around the time of the P wave), and the ventricles contract second (around the time of the QRS complex). Ventricular relaxation occurs around the time of the T wave.
34.
What heart's electrical axis refers? The heart's electrical axis refers to the general direction of the heart's depolarization wave front (or mean electrical vector) in the frontal plane.
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35.
What is the orientation of heart's electrical axis? It is usually oriented in a right shoulder to left Leg direction, which corresponds to the left inferior quadrant of the hex axial reference system, although -30o to +90o is considered to be normal.
36.
What does the electric axis of the heart usually denote? The concept of the electric axis of the heart usually denotes the average direction of the electric activity throughout ventricular (or sometimes atrial) activation.
37.
What is the range of electric axis?
38.
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The normal range of the electric axis lies between +30° and -110° in the frontal plane and between +30° and -30° in the transverse plane. The direction of the electric axis may be approximated from the 12-Lead ECG by finding the Lead in the frontal plane, where the QRS-complex has largest positive deflection. The direction of the electric axis is in the direction of this Lead vector. The result can be checked by observing that the QRS-complex is symmetrically biphasic in the Lead that is normal to the electric axis. What does the deviation of the electric axis to the right indicate?
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Deviation of the electric axis to the right is an indication of increased electric activity in the right ventricle due to increased right ventricular mass.
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39.
Due to which types of diseases does the deviation of the electric axis to the right occur?
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What does the deviation of the electric axis to the left indicates?
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This is usually a consequence of chronic obstructive lung disease, pulmonary emboli, certain types of congenital heart disease, or other disorders causing severe pulmonary hypertension.
Due to which types of diseases do the deviation of the electric axis to the left occur?
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Deviation of the electric axis to the left is an indication of increased electric activity in the left ventricle due to increased left ventricular mass.
This is usually a consequence of hypertension, aortic Stenosis, ischemic heart disease, or some inter ventricular conduction defect. 42.
What is the amplitude of ‘P’ wave? Amplitude: 0.25mV
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What should be the dimensions of ‘P’ wave? The P wave in general should not be more than 1 box wide or 1 box tall. If it exceeds these, it generally means that either or both atria is enlarged (hypertrophied).
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44.
What are the characteristics of ‘P’ wave? Positive deflection of P wave greater than 1 box wide or 1 box in height indicates right atrial hypertrophy Negative deflection of P wave greater than 1 box wide or 1 box in depth indicates left atrial hypertrophy.
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What is the duration of PR-Interval? Duration: 180-220 m sec, the distance from the beginning of the P wave to the beginning of Q wave is PR interval. It’s a period from the beginning of atria depolarization to the beginning of ventricular depolarization.
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What is PR-segment? It is the distance from end of the P wave and beginning of Q wave. What is the duration of PR-segment?
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Duration: 0.01 sec (approximately) What is the amplitude of Q wave?
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Amplitude: 0.2 mV
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What does the normal Q wave represent?
When does the Q wave Develop?
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Normal Q waves are small, less than 1 mm deep or wide and one fourth the height of their R wave.
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Pathological Q waves usually develop when ST segments are elevated and appear several hours or days after the clinical manifestations of the Myocardial Infarction. What does the abnormal Q wave represent?
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Abnormal Q must be one Small Square (0.04 sec) wide and greater than one third of QRS height in Lead III. Myocardial infarction causes pathological Q waves over the affected area of the ventricle. The age of the infection can be determined. If only Q wave is present without elevated ST segment then it indicates old infarction while if ST segment is there (with or without T wave inversion) then it indicates acute infraction. Q waves with inverted T waves may indicate undetermined age.
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52.
What is the amplitude of ‘R’ Wave? Amplitude: 1mV
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What does the ‘R’ wave represent? R wave is the largest wave of the ECG graph and it is always above is electric line, No such thing as a "negative R-wave" exists.
54.
What is the amplitude of ‘S’ Wave? Amplitude: 0.4 - 0.5 mV
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55.
What is the amplitude of ‘QRS’ Complex? Amplitude: 1.5 mV
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What is the duration of ST-Segment? Short segment from end of S wave to beginning of T wave and has duration of about 0.07 sec.
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What is the amplitude of ‘T’ Wave? Amplitude: 0.1 - 0.5 m sec
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What does normal ‘T’ wave represent?
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Normal T waves are in the same direction as their complex, wave is asymmetrical and it peaks toward the end, instead of the middle. Normal T wave in frontal plan is about 5 mm and in pericardial plane 10 mm tall. What is the duration of ST-Interval?
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Period from end of S wave to end of T wave and has the duration of about 0.20 0.27 m sec. What does QT-Interval represent?
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It is the interval from beginning of Q wave to end of T wave, or we can say this is the period from beginning of ventricular depolarization to the end of repolarization. What is the duration of QT-Interval?
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It has the duration of about 0.26 - 0.49 m sec. What does the RR-Interval represent?
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This is the distance between QRS-complexes. What is the amplitude of ‘U’ Wave?
64.
Classify Cardiac Rhythm Diagnosis?
Cardiac rhythms may be divided into two categories
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Supra ventricular (above the ventricles)
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Ventricular rhythms.
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Amplitude: 0.15 mV
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Which node does trigger the cardiac activation? The sinus node triggers the cardiac activation.
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How is the cardiac activation diagnosed? This is easily diagnosed by noting that the three deflections, P-QRS-T, follow in this order and are differentiable.
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67.
Give the frequency range of sinus rhythm? The sinus rhythm is normal if its frequency is between 60 and 100/Min.
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What is sinus Bradycardia? Sinus rhythm having frequency less than 60/Min is called sinus Bradycardia.
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What is sinus tachycardia? Sinus rhythm of frequency higher than 100/ min is called sinus tachycardia. It occurs most often as a physiological response to physical exercise or psychical stress, but may also result from congestive heart failure.
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What is sinus arrhythmia?
71.
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If the sinus rhythm is irregular such that the longest PP- or RR-interval exceeds the shortest interval by 0.16 s, the situation is called sinus arrhythmia. When does the heart rate increase or decrease?
What do you understand by atrial flutter?
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The nerve is active during respiration and, through its effect on the sinus node, causes an increase in heart rate during inspiration and a decrease during expiration. The effect is particularly pronounced in children.
What is frequency range of atrial flutter?
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When the heart rate is sufficiently elevated so that the iso-electric interval between the end of T and beginning of P disappears, the arrhythmia is called atrial flutter. The origin is also believed to involve a re-entrant atrial pathway.
74.
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The frequency of these fluctuations is between 220 and 300/min. The AV-node and, thereafter, the ventricles are generally activated by every second or every third atrial impulse (2:1 or 3:1 heart block). Due to what reason does atrial fibrillation occur?
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Atrial fibrillation occurs as a consequence of rheumatic disease, atherosclerotic disease, hyperthyroidism, and pericarditis (It may also occur in healthy subjects as a result of strong sympathetic activation.) 75.
What is the phenomenon of junctional rhythm? If the heart rate is slow (40-55/Min.), the QRS-complex is normal, the P-waves are possibly not seen, and then the origin of the cardiac rhythm is in the AV node. Because the origin is in the junction between atria and ventricles, this is called junctional rhythm.
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76.
Why QRS-complex is of relatively short duration? In ventricular arrhythmias ventricular activation does not originate from the AV node and/or does not proceed in the ventricles in a normal way. If the activation proceeds to the ventricles along the conduction system, the inner walls of the ventricles are activated almost simultaneously and the activation front proceeds mainly radically toward the outer walls. As a result, the QRS-complex is of relatively short duration.
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What does indicate abnormal ventricular activation? A QRS-interval lasting longer than 0.1 s indicates abnormal ventricular activation.
78.
What is idioventricular rhythm?
79.
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If the ventricles are continuously activated by a ventricular focus whose rhythm is under 40/Min, the rhythm is called idioventricular rhythm. Which situation is called accelerated idioventricular rhythm?
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What is ventricular tachycardia?
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The ventricular activity may also be formed from short (less than 20 s) bursts of ventricular activity at higher rates (between 40 and 120/Min). This situation is called accelerated idioventricular rhythm.
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What is ventricular fibrillation?
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A rhythm of ventricular origin may also be a consequence of a slower conduction in ischemic ventricular muscle that leads to circular activation (reentry). The result is activation of the ventricular muscle at a high rate (over 120/Min.), causing rapid, bizarre, and wide QRS-complexes; the arrhythmia is called ventricular tachycardia. As noted, ventricular tachycardia is often a consequence of ischemia and myocardial infarction.
82.
What is the cause of ventricular fibrillation?
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When ventricular depolarization occurs chaotically, the situation is called ventricular fibrillation.
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The cause of fibrillation is the establishment of multiple re-entry loops usually involving diseased heart muscle. In this arrhythmia the contraction of the ventricular muscle is also irregular and is ineffective at pumping blood. The lack of blood circulation leads to almost immediate loss of consciousness and death within minutes. The ventricular fibrillation may be stopped with an external defibrillator pulse and appropriate medication. 83.
What are pacer rhythm and its frequency? A ventricular rhythm originating from a cardiac pacemaker is associated with wide QRS-complexes because the pacing electrode is (usually) located in the right ventricle and activation does not involve the conduction system. In pacer rhythm the ventricular contraction is usually preceded by a clearly visible pacer impulse spike. The pacer rhythm is usually set to 72/min.
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84.
On what basis sinus rhythm is diagnosed? If the P-waves always precede the QRS-complex with a PR-interval of 0.12-0.2 s, the AV conduction is normal and a sinus rhythm is diagnosed. If the PR interval is fixed but shorter than normal, either the origin of the impulse is closer to the ventricles or the atrioventricular conduction is utilizing an (abnormal) bypass tract leading to pre-excitation of the ventricles. The latter is called the Wolff-Parkinson-White syndrome and is discussed below. The PR-interval may also be variable, such as in a wandering atrial pacemaker and multifocal atrial tachycardia.
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How first-degree atrioventricular block is diagnosed? When the P-wave always precedes the QRS-complex but the PR-interval is prolonged over 0.2 s, first-degree atrioventricular block is diagnosed.
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86.
What is Wenkebach phenomenon?
What is third-degree atrioventricular block?
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If the PQ-interval is longer than normal and the QRS-complex sometimes does not follow the P-wave, the atrioventricular block is of second-degree. If the PR interval progressively lengthens, leading finally to the drop out of a QRS complex, the second degree block is called a Wenkebach phenomenon.
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Bundle-branch block denotes a conduction defect in either of the bundle branches or in either fascicle of the left bundle-branch. If the two bundle branches exhibit a block simultaneously, the progress of activation from the atria to the ventricles is completely inhibited; this is regarded as third-degree atrioventricular block. What is duration criterion for the QRS-complex bundle-branch block?
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If the right bundle-branch is defective so that the electrical impulse cannot travel through it to the right ventricle, activation reaches the right ventricle by proceeding from the left ventricle. It then travels through the septal and right ventricular muscle mass. This progress is, of course, slower than that through the conduction system and leads to a QRS-complex wider than 0.1 s. Usually the duration criterion for the QRS-complex in right bundle-branch block (RBBB) as well as for the left bundle- branch block (LBBB) is >0.12 s.
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Warranty 1)
We guarantee this product against all manufacturing defects for 24 months from the date of sale by us or through our dealers. Consumables like dry cell etc. are not covered under warranty.
2)
The guarantee will become void, if a)
The product is not operated as per the instruction given in the Learning Material
b)
The agreed payment terms and other conditions of sale are not followed.
c)
The customer resells the instrument to another party.
d)
Any attempt is made to service and modify the instrument.
The non-working of the product is to be communicated to us immediately giving full details of the complaints and defects noticed specifically mentioning the type, serial number of the product and date of purchase etc.
4)
The repair work will be carried out, provided the product is dispatched securely packed and insured. The transportation charges shall be borne by the customer.
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List of Accessories
1. Clamp Electrodes...........................................................................................4 Nos.
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2. Suction cup electrodes..................................................................................6 Nos.
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3. ECG Lead cable............................................................................................1 No. 4. ECG gel.........................................................................................................1 No.
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5. Stylus for touch screen.................................................................................1 No. 7.
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6. Learning Material..........................................................................................1 No. Power supply..............................................................................................1 No.
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