1. ECG
Heartbeat on a paper

2. Electrical conduction system of heart
 SA node
 Atria
 AV node
 His bundle
 L & R bundles
 Ventricles

3. ECG leads

4. All Limb Leads

5. Anatomic Groups
(Summary)

6. A heartbeat
 P- atrial depolarization
 QRS- ventricular depolarization
 T- ventricular repolarization

7. Interpreting ECG
 Rate-
 <60 bradycardia, >100 tachycardia
 Rhythm- relation of P & QRS
 Regular or irregular
 Axis- use QRS in leads I & aVF
 0-90 normal, <0 LAD, >90 RAD
 P wave- best seen in lead II
 Peaked P- P pulmonale- RAH, wide bifid P- P mitrale- LAH
 PR interval- normal ~0.2 sec.
 Short- WPW syndrome, long- AV blocks

8. Interpretation- continued
 QRS complex- normal <0.12 sec
 Broad- ectopic, BBB-RSR’ in V1 RBBB, ‘M’ in V1 LBBB
 Q wave >2 mm is pathological, suggesting old MI
 ST segment- difficult to interpret with BBB
 Depressed- ischemia, elevated- infarction
 Saddle shaped across the leads- pericarditis
 QT interval- normal ~0.4 sec
 Prolongation predisposes to ventricular arrythmias
 T wave- upright in all, except III & V1
 Tall tented- hyperkalemia
 Inverted- ischemia, previous infarction, hypokalemia

9. A normal ECG

10. Commonest arrythmia
Sinus brady/tachycardia
Ectopics- atrial/ventricular
Majority do not require Rx

11. Bradycardia- AV blocks
 1st
degree-
prolonged PR
 2nd
degree-
regular P & regular QRS,
uncoordinated
 3rd
degree-
irregular P & wide QRS

12. Treatment
Atropine
Pacemaker-
(temporary/permanent)

13. Tachyarrythmia
 Rate >100 bpm
 Types-
 Narrow-complex- supraventricular
Irregular- Atrial fibrillation
Regular at 300/150 bpm- Atrial flutter
Regular >150- AVNRT/AVRT
 Broad-complex- ventricular or SVT with BBB
h/o CAD- VT, unless proved otherwise

14. Management
 Unstable- DC cardioversion
 Stable-
 Asymptomatic ectopics- don’t treat
 Supraventricular- try carotid massage/valsalva
 Anti-arrythmics- Amiodarone-VT, Adenosine-SVT
 RF ablation, Maze surgery, AICD
 Control precipitating factors
 MI, infection, thyrotoxicosis, alcohol, caffeine,
electrolyte disorders, drug toxicity