The long R-P' tachycardias.

The family of tachycardias that are called long R-P' tachycardias represent a unique group of tachycardias which have been notably refractory to pharmacologic therapy in the past. On the surface electrocardiogram, the rhythms may be indistinguishable. It is only with careful electrophysiological evaluation in many cases that these rhythms can be sorted out. The differential diagnosis in these rhythms is important because with incessant tachycardia, ventricular dysfunction may be produced. In many of the instances of long R-P' tachycardias definitive and directed ablation of the tachycardia can be accomplished. New techniques involving catheter ablation and super-selective surgical dissection are now present which makes ablation of these tachycardias possible.