The document discusses the electrocardiogram (ECG), which represents the electrical events of the cardiac cycle, providing insights into conditions like arrhythmias and myocardial ischemia. It details the heart's electrical conduction system, including the roles of the SA node and AV node, as well as the interpretation of various waveforms and intervals on the ECG. Additionally, it covers the significance of cardiac axis deviations and the influence of cardiac structure and health on the electrocardiographic readings.

1. PRESENTER: REKHA MARBATE

2.  Electric wiring of heart
 Normal ECG
 PR interval
 QRS complex
 Cardiac axis
 Axial Deviation
 How to report ECG
 Example

4. What is an EKG/ECG?
• The electrocardiogram (ECG) is a representation of the electrical
events of the cardiac cycle.
• Each event has a distinctive waveform
• the study of waveform can lead to greater insight into a patient’s
cardiac patho-physiology.

5. With ECGs we can identify
 Arrhythmias
 Myocardial ischemia and infarction
 Pericarditis
 Chamber hypertrophy
 Electrolyte disturbances (i.e. hyperkalemia, hypokalemia)
 Drug toxicity (i.e. digoxin and drugs which prolong the QT interval)

6. Depolarization
• Contraction of any muscle is associated with electrical changes
called depolarization
• These changes can be detected by electrodes attached to the surface
of the body

7. Pacemakers of the Heart
• SA Node - Dominant pacemaker with an intrinsic rate of 60 - 100
beats/minute.
• AV Node - Back-up pacemaker with an intrinsic rate of 40 - 60
beats/minute.
• Ventricular cells - Back-up pacemaker with an intrinsic rate of 20 -
45 bpm.

8. Sinoatrial node
AV node
Bundle of His
Bundle Branches
Purkinje fibers

9. The “PQRST”
• P wave – Atrial depolarization
• T wave – Ventricular repolarization
• QRS – Ventricular depolarization

11. The ECG Paper
• Horizontally • Vertically
– One small box - 0.04 s – One large box - 0.5 cm
– One large box - 0.20 s 1mv signal moves stylus by 1cm

14.  If PR interval is short ,suggest excitation takes place through AV
conduction or spread/ conduction is abnormally fast from atrium to
ventricle

15. •Duration of QRS
complex suggest the
time taken for impulse
to excite through
ventricle.
• Normally= 0.12 or
less, if it is more QRS
complex get widen

16.  The standard EKG has 12 leads:
 3 Standard Limb Leads
 3 Augmented Limb Leads
 6 Precordial Leads

17. 3 Standard Limb Leads + 3 Augmented leads

19. Lat
sur
RT
atrium

20. Limited amount of information is also provided by height of P wave, QRS
complex and T wave ,if machine is properly calibrated.
Small complex- pericardial effusion and tall R wave indicate left
ventricular hypertrophy

22.  Average direction of spread of depolarization wave through the ventricle
as seen from front is called cardiac axis.

24.  Rt axial deviation:- rt ventricular hypertrophy, associated with pulmonary
condition put strain on rt side of heart and with congenital heart disease.
(pulmonary embolus)
 Lt axial deviation: lt ventricular hypertrophy, mostly problem is conduction
defect rather than increase in left ventriclar muscle bulk.

25.  Transition point:
point where R and S
are equal indicate
position of interventricular
septum
 If right ventricle enlarges to
Occupies more of pericardium
than normal , transition point
move from V3-V4 to V4-V5
or sometime V5-V6, this
clockwise rotation suggestive
Of chronic lung disease.

26.  Rhythm
 Conduction interval
 Cardiac axis
 Descripsion of QRS complex
 Description of ST segment and T wave