Mechanism of postextrasystolic potentiation in the right ventricle.

The mechanism of postextrasystolic potentiation (PESP) has been studied in the left ventricle in humans; however, this phenomenon has not been evaluated in the right ventricle. Accordingly, 18 sinus beats were compared to postextrasystolic beats during the same cineventriculogram using simultaneous high-fidelity right ventricular (RV) and pulmonary artery pressures and cast-validated biplane cineventriculographic volumes in normal patients. The increase in cycle length was 22 +/- 12% (standard deviation) in the postextrasystolic beats. Right ventricular ejection fraction increased from 61 +/- 10 to 68 +/- 4% (p less than 0.001) and RV stroke volume increased from 99 +/- 18 to 128 +/- 20 ml (p less than 0.001) due to an increase in RV end-diastolic volume (165 +/- 34 to 189 +/- 30 ml, p less than 0.001) as RV end-systolic volume (65 +/- 24 to 61 +/- 17 ml, difference not significant) and RV end-systolic pressure (16 +/- 7 to 17 +/- 6 mm Hg, difference not significant) remained unchanged. Despite an increase in RV systolic pressure from 29 +/- 7 to 31 +/- 7 mm Hg (p less than 0.01) and an increase in RV end-diastolic pressure from 8 +/- 4 to 10 +/- 5 mm Hg (p less than 0.001), RV +dP/dtmax did not change (318 +/- 102 to 294 +/- 82 mm Hg/s, difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)