The relation of heart rhythm to postextrasystolic potentiation.

In 9 patients with various forms of heart rhythms and rates, all of whom had a temporary pacemaker electrode inserted, several single premature ventricular contractions (PVC) with various coupling intervals (CI) were induced. The relative systolic area of the carotid pulse curve in the postextrasystolic beat was used as an indicator of the degree of postextrasystolic potentiation (PESP). A close correlation between PESP and CI was found only in sinus rhythm patients (r = -0.85). The patients with junctional and ventricular rhythms had no PESP regardless of CI or the degree of heart failure. Compensatory pause (CP) in these patients surprisingly related (r = 0.95) to heart rate, slower rates having a shorter relative CP.