c. Ventricular Tachycardia.
(1) Analysis. The rhythm of the heart is usually regular, but the rhythm can
be slightly irregular. The heartbeat rate is from 150 to 250 beats per minute. The rate
can exceed 250 beats per minute of the heart rhythm progressing to ventricular flutter.
Occasionally, the rate may be slower than 150 beats per minute; the condition is then
termed slow ventricular tachycardia (VT). P waves are not normally seen; however,
dissociated waves may be seen. The focus is in the ventricles, and there will be no PR
interval. The QRS complex is wide and bizarre. The complex may be 0.12 of a second
or greater. The T wave is usually in the opposite direction from the R wave. Ventricular
tachycardia is serious and dangerous. It may be the precursor of ventricular fibrillation.
If VT persists, there may be a marked reduction in cardiac output.
(2) Treatment. Begin with lidocaine intravenously unless the situation is
critical, then give a DC countershock.
If the casualty has no pulse, treat as you would for ventricular fibrillation.
Treatment for a stable and unstable casualty is not the same.
(a) Stable casualty. Follow this procedure for the casualty who has no
symptoms (no chest pain or dyspnea, adequate blood pressure, and a pulse):
1 Administer lidocaine 1 mg/kg intravenously bolus. This may be
followed by 0.5 mg/kg intravenously every 8 minutes until the ventricular tachycardia
resolves or up to 3 mg/kg intravenously.
2 Give procainamide 2 mg/minute intra-venously until the
ventricular tachycardia resolves or up to 1,000 mg intravenously. (Use procainamide if
lidocaine doesn't work.)
3 If drug therapy is not successful, perform low energy
cardioversion of 50 joules.
4 If a defibrillator is available, use a mechanical means of
conversions ("chest thump" or "cough.")
Mechanical conversion may cause ventricular fibrillation.