The document discusses the basics of electrocardiography including the electrical conduction system of the heart, the placement of ECG leads, components of the ECG waveform, and how to interpret key aspects of the ECG such as heart rate, rhythm, intervals, and complexes. It also summarizes the most common arrhythmias like bradycardia, atrial fibrillation, atrial flutter, and ventricular tachycardia, as well as their typical treatments with medications, cardioversion, ablation, or pacemaker implantation.

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