Transvenous pacing in the presence of acute right ventricular infarction.

Ventricular tachycardia and ventricular fibrillation are very frequent during transvenous pacing in the presence of acute right ventricular infarction. An acceptable pacing threshold is not usually achieved. A relatively high pacing threshold should, therefore, be accepted in these cases with minimum catheter manipulation. Invisible or very small pacing spikes, increased time intervals between the spike and paced QRS, atypical QRS configurations and sensing failure are frequent in these cases.