Effects of nitroglycerin, postextrasystolic potentiation, and pacing-induced ischaemia on wall motion in patients with ischaemic heart disease.

Abstract

The influence of nitroglycerin, postextrasystolic potentiation, and rapid ventricular pacing on total and regional ventricular function was studied in 32 patients with normal ventricular function and in 44 patients with left ventricular asynergy caused by obstructive coronary artery disease. Total ventricular function was assessed by ventriculography and regional ventricular function was analysed by use of 7 hemiaxes. Nitroglycerin increased ejection fraction and decreased left ventricular systolic and end-diastolic pressures in the normally functioning ventricles; apical wall motion increased, while basal wall motion remained unchanged after nitroglycerin in these ventricles. Pressures fell significantly in ventricles with asynergy after nitroglycerin; ejection fraction decreased while wall motion in asynergic areas was inconsistently influenced. Postextrasystolic potentiation augmented ejection fraction by a powerful and homogeneous increase of wall motion in normally functioning ventricles. Asynergic areas and normal areas in diseased ventricles showed identical augmentation of wall motion after a premature beat. Rapid venticular pacing produced a significant increase in end-diastolic pressure and a fall in ejection fraction in patients with obstructive coronary artery disease. Wall motion in normal areas perfused by arteries with critical stenoses was dramatically depressed after pacing, while asynergic areas and normal areas perfused by normal arteries remained unchanged. The results show that normal contractile behaviour can be detected by postextrasystolic potentiation in asynergic areas, suggesting that some normally perfused muscle exists in these areas. Pacing stress does not further deteriorate function in asynergic areas, which suggests the presence of viable and well perfused muscle (within scar tissue) whose function may not profit from revascularization. Pacing-induced asynergy identifies the functional significance of coronary stenoses and suggests that bypass surgery might be beneficial.

Comparison between the effect of postextrasystolic potentiation and the effect of nitrates on left ventricular function for the differentiation between reversible and irreversible left ventricular asynergy

“…Therefore, several groups have investigated the effects of nitrates or the effect of postextrasystolic (PES) potentiation on asynergic segments of the LV wall (2,3,4,5). The judgement concerning the diagnostic meaning of each of the two interventions is in essence equivocal.…”

“…There is controversy concerning the efficacy of nitrates and the PES potentiation for this differentiation: Banka et al (2) and KIausner et al (9) assume that both interventions have similar effects on asynergic areas, whereas Schwarz et al (5) suppose that the potentiation by the PES beat seems to be superior to the effect of nitrates. In the present study, therefore, the effect of both nitrates and PES potentiation were investigated in the same patient.…”

Left Ventricular Function in Myocardial Ischaemia

“…One obvious way is by postextrasystolic potentiation technique. After premature ventricular beat, either naturally occurring or induced by pacing catheter, the filling is enchanced and, as has been illustrated by several investigators, the affected areas show potentiation of the inward movement (19,20). This inward postextrasystolic potentiation is, however, depen-dent on an increase in left ventricular volume and on the basal amplitude of the low flow area (20).…”

Effect of postextrasystolic potentiation on amplitude and timing of regional left ventricular wall motion in ischaemic heart disease.

“…The verical lines represent the timing ofminimum cavity area and mitral valve opening. 11 were made of superimposed cavity outlines during systole and diastole (Fig. 1).…”