Sunday, 22 November 2009

Basic Electrocardiology

Basic ECG Interpretation

P wave- atrial depolarization
PR segment- conduction delay through AV node
PR interval- atrial depolarization and conduction delay through AV node
QRS- ventricular depolarization
ST segment- isoelectric; ventricles still depolarized
QT interval- ventricular depolarization and ventricular repolarization
T wave- Ventricular repolarization

Normal Cardiac Rhythm Parameters
Normal sinus rhythm -----------between 60 and 100 bpm
Sinus bradycardia-------------- less than 60 bpm
Sinus tachycardia --------------over 100 bpm
QRS width---------------------- between 0.08 and 0.12 sec
PR interval ----------------------between 0.12 and 0.20 sec
QT interval ----------------------0.30-0.40 sec
Atrial rate, inherent------------ 60-100 bpm
Junctional rate, inherent ------ 40-60 bpm
Ventricular rate, inherent ----- 20-40 bpm

FIGURING RATE (for regular rhythms only)
1. 1500 method
- divide 1500 by the number of small squares between two consecutive QRS complexes
2. R-R method
- find a QRS where the peak R wave falls on a heavy dark line. USe this QRS as reference then take note where the next QRS falls. Starting from the next heavy line, count 300, 150, 100, 75, 60, 50, 40.
3. 6-second method
- count the number of QRS complexes in a 6 second strip and multiply by 10
9:05 AM