Abstract
The effects of postextrasystolic potentiation (PESP) on systolic time intervals and left ventricular wall motion were studied during diagnostic cardiac catheterization in 20 patients (4 normal individuals, 11 patients with coronary artery disease and 5 patients with idiopathic dilated cardiomyopathy). Postextrasystolic changes in the aortic pressure and systolic time intervals were measured from the electrocardiogram and aortic pressure tracing. After a micromanometer-tipped catheter was positioned in the ascending aorta just above the aortic valve, a single ventricular premature beat was introduced using an R-wave coupled stimulator. PESP was then studied during left ventriculography which was undertaken simultaneously in the right anterior oblique 30° and left anterior oblique 60° positions. Following two or three normal sinus beats, a right ventricular extrastimulus was delivered again under the same stimulating condition. PESP in all patients caused a decrease in the ratio of the preejection period to the left ventricular ejection time (PEP/ET). The average percent decrease was 21% (from 0.429±0.162 to 0.339±0.102, p<0.001). The left ventricular ejection fraction (EF) increased in all patients with PESP from 0.52±0.20 to 0.61±0.17 (p<0.001). The postextrasystolic changes in the PEP/ET ratio and EF were greater in patients with low cardiac performance. There was a good correlation (r=-0.85, p<0.001) between the changes in the EF and those in PEP/ET in PESP. Thus, it is possible to determine left ventricular residual function (the postextrasystolic change in the global EF) using the postextrasystolic change in PEP/ET in patients with coronary artery disease and dilated cardiomyopathy.
