Influence of timing of the extrasystolic beat on the extent of postextrasystolic potentiation in the intact human left ventricle.

Abstract

The analysis of the post-extrasystolic (PES) beat, which follows an at random elicited extrasystole, has been used frequently in clinical studies for the evaluation of the functional reserve of the left ventricle. Therefore, the relation between the PES potentiation and the normalized coupling interval (RR'/RR) and the normalized length of the PES pause (R'R/RR) were investigated in patients with and without coronary heart disease by means of programmed extrasystoles. The PES increase of the maximal rate of left ventricular (LV) pressure rise (max dP/dt) showed a good exponential correlation with the coupling interval in the individual patients (r=0.87–0.99) and with length of the PES pause (r=0.87–0.99), as interpolated extrasystoles were excluded. With interpolated extrasystoles the correlation between the max dP/dt-increase and the length of the PES pause became much weaker (r=0.24 resp. 0.33 in two patients). As an angiographic ejection phase parameter of LV function the ejection fraction was analyzed. The change of EF in the PES beat was completely independent (r=0.05) from the coupling interval of tje preceding extrasystole and showed an only moderate correlation to the length of the PES pause (r=0.67), which became weaker when the interpolated extrasystoles were excluded (r=0.46).