ECG. OR EKG ELECTRO CARDIO GRAPHY .pptx

ECG is a three letter acronym for ElectroCardioGraphy.
The word is derived from electro(greek for electricity),cardio(greek for heart) and graph(Greek root meaning "to write“)
An ECG (electrocardiogram) is a test that records the electrical activity of your heart over time

1. ecg S.Rekha Associate professor, EGSPCOP.

2. ECG ECG is a three letter acronym for ElectroCardioGraphy . The word is derived from electro( greek for electricity),cardio( greek for heart) and graph(Greek root meaning "to write“) An ECG (electrocardiogram) is a test that records the electrical activity of your heart over time. It is a transthoracic interpretation of the electrical activity of the heart over time captured and externally recorded by skin electrodes. It's a non-invasive procedure that helps doctors diagnose and monitor heart conditions by measuring the electrical signals produced by the heart's muscle contractions.  ECG is the gold standard for the noninvasive diagnosis of cardiac diseases

3. INDICATIONS OF ECG Gold standard for diagnosis of cardiac arrhythmias Helps detect electrolyte disturbances (hyper- & hypokalemia) Allows for detection of conduction abnormalities Screening tool for ischemic heart disease during stress tests Helpful with non-cardiac diseases (e.g. pulmonary embolism or hypothermia ECG is a diagnostic tool, NOT a treatment No one is ever cured by an ECG!! 

4. BASIC ELECTROPHYSIOLOGY PHYSIOLOGICAL PROPERTIES OF MYOCARDIAL CELL Automaticity : ability to initiate an impulse Excitability : ability to respond to a stimulus Conductivity : ability to transmit an impulse Contractility : ability to respond with pumping action Depolarization and repolarization of a cardiac cell generates action potential ECG is the composite representation of action potential of all cardiac cell.

5. ELECTRICAL CONDUCTION SYSTEM OF THE HEART The electrical discharge for each cardiac cycle normally starts in a special area of the right atrium called the ‘ sinoatrial (SA) node’. Depolarization then spreads through the atrial muscle fibres. There is a delay while the depolarization spreads through another special area in the atrium, the ‘ atrioventricular (AV) node’. Thereafter , the electrical discharge travels very rapidly, down specialized conduction tissue: first a single pathway, the ‘bundle of His’, which then divides in the septum between the ventricles into right and left bundle branches

6. Within the ventricular mass, conduction spreads somewhat more slowly , through specialized tissue called ‘Purkinje fibres’. Tissue Conduction rate m/s SA node 0.05 Atrial pathway 1 AV node 0.05 Bundle of his 0.05 Purkinje system 4 Ventricular mass 1

7. CONDUCTION OF THE IMPULSE: Normal resting membrane potential=-90mv If the potential rises from -90 to 0, then this excites a further rise of potential, called the action potential. The action potential is transmitted throughout the cell and forms the impulse. During the rise of potential, the membrane becomes permeable to Sodium ions and the potential rises to a positive direction. This phenomena is called depolarization. The Sodium channels close and there is rapid diffusion of K+ ions into the exterior, reestablishing the resting membrane potential. This is called Depolarization is followed by muscle contraction and repolarization is followed by muscle relaxation

8. NORMAL SINUS RHYTHM A normal sinus rhythm comprises of the following waves:- • P waves- denotes atrial depolarization(electrical vector is directed from the SA node towards the AV node) • QRS complex- denotes depolarization of ventricles as well as repolarization of atrium • T waves- denotes the repolarization (or recovery) of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period. As depicted in the fig:- •PR interval- beginning of the P wave to the beginning of the QRS complex • ST segment- connects the QRS complex and the T wave. • QT interval- the beginning of the QRS complex to the end of the T wave

9. What differentiates a segment from an interval? A segment is a straight line connecting two waves. An interval encompasses at least one wave plus the connecting straight line

10. J point-  J-point is the point at which the QRS complex meets the ST wave. Its an isoelectric point and its importance lies in the fact that ST segment elevation is measured with respect to it J WAVE AND U WAVE: These are two abnormal waves that may be seen sum time in the ecg recordings.

11. J wave also known as camel-hump sign, late delta wave, hathook junction, hypothermic wave, prominent J wave ,K wave, H wave or current of injury positive deflections occurring at the junction between the QRS complex and ST segment(j point) observed in people suffering from hypothermia with a temperature of less than 32

12. U wave • Typically small, and by definition, follows the T wave • Prominent U waves are most often seen in hypokalemia, but may be present in hypercalcemia, thyrotoxicosis

13. RECORDING THE ELECTROCARDIOGRAM THE E.C.G PAPER ECG machines record changes in electrical activity by drawing a trace on a moving paper strip. The electrocardiograph uses thermal paper, which is a graph paper & runs normally at a speed of 25mm/sec Time is plotted on the X axis & voltage is plotted on the Y axis. In X axis, 1 second is divided into 5 large squares each of which represents 0.2 sec.

14. Each large square is further divided into 5 small squares which represents 0.04 sec. The ECG machine is calibrated in such a way that an increase of voltage by 1 mVolt should move the stylus vertically by 1cms

15. ECG PAPER • Fig adjacent shows a callibration graph . The calibration signal should be included with every record

16. ELECTROCARDIOGRAPHIC LEADS: Electrocardiographic Leads (ECG or EKG leads) are specific viewpoints from which the heart’s electrical activity is recorded. These leads give a multi-dimensional picture of the heart, helping to diagnose arrhythmias, myocardial infarctions, and other cardiac conditions . These leads, attached to the body via electrodes, allow for a graphical representation of the heart's electrical signals . The standard 12-lead ECG uses 10 electrodes to create 6 limb leads and 6 precordial (chest) leads, offering different perspectives of the heart's electrical activity. 

17. There are two main types of leads: Limb Leads These are placed on the arms and legs and record the heart’s electrical activity in the frontal plane (vertical slice of the body). a. Standard Bipolar Limb Leads (Einthoven’s Triangle) Lead I: Right arm (-) to Left arm (+) Lead II: Right arm (-) to Left leg (+) Lead III: Left arm (-) to Left leg (+) b . Augmented Unipolar Limb Leads aVR : Augmented Voltage Right arm aVL : Augmented Voltage Left arm aVF : Augmented Voltage Foot (left leg)

18. 2. Precordial (Chest) Leads These leads record the electrical activity in the horizontal plane (cross-sectional slice of the chest). They are unipolar and placed directly on the chest .

19. MAKING A RECORDING: Good contact between body surface and electrode is necessary. It might be essential to shave the chest and apply electro cardio graphic jelly The patient must lie down and relax to prevent muscle tremor Connect up the limb electrodes to the correct limb . L imb electrodes have marking on them and also they are colour coded ( red –right arm , yellow -left arm , green left leg and black-right leg) Calibrate the record with 1mv signal. There shouldn’t be over damping or underdamping. Any metallic object like watch or jewellary should be remove from the patients body 4-5 recording of each lead is recorded

20. Interpretation ( adults) Normal: 50 – 100 bpm Tachycardia: > 100 bpm Bradycardia: < 50 bpm

21. Some pathological entities which can be seen on the ECG:

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