ECG-ALGORITHM

RATE

1. ASSESS RATE: 300/(large squares) interval in mm. Bradycardia if HR < 60/min; tachycardia if HR > 100/min.

RYTHM

2. ASSESS RYTHM: RR intervals (1 small square variation is normal) & check that a P precedes a QRS complex.

INTERVALS

3. EXAMINE PR INTERVAL: normal 120-200ms, prolonged if heart block present.

4. EXAMINE QRS INTERVAL: normal < 100ms. Prolonged in BBB, WPW, ventricular pacemaker, tricyclics.

5. EXAMINE QT INTERVAL: 340-470 ms. Prolonged in tricyclic overdose, hypo-Ca/Mg/K, starvation, hypothermia, quinidine, sotalol, amiodarone use.

WAVEFORMS

6. INTERPRET WAVEFORM.

7. ASSESS ST-SEGMENT: elevated in ACS, pericarditis, Prinzmetal angina and others.

OTHERS

8. ASSESS AXIS: Normal is -30 to +100. +I +aVF: normal; -I +aVF: RAD; +I -aVF: LAD; -I -aVF: RAD/LAD. LAD is a marker for CAD, RAD is normal for children, young adults; RVH in older adults.

9. ASSESS HYPERTROPHY:

10. ASSESS BRANCH BLOCK: LBBB (QRS 120-180 ms), RBBB (QRS > 120 ms)