Assessment of left ventricular function in ischemic heart disease. The relation between pressure decay during the isovolumic relaxation phase and regional wall motion abnormality.

Abstract

We examine whether regional wall motion abnormality (RWMA) could contribute to the slowed relaxation rate of the left ventricle (LV) in patients with coronary artery disease (CADpts). Simultaneous observations were made on the time constant (Tc) of the isovolumic pressure decay and left ventriculography at the control period and after right atrial pacing. Subsequently, the subjects investigated were divided into 3 groups, i.e. normal subjects (Group I, n = 8), CADpts with normal wall motion during the control period (Group II, n = 21), and CADpts with RWMA during the control period (Group III, n = 28). The latter two groups were further divided into two subgroups according to the presence (Group IIa and IIIa) or absence (Group IIb and IIIb) of pacing-induced RWMA. We measured Tc by a method of exponential analysis that could estimate the asymptote. During the control period, Tc was significantly prolonged in Group III (82 +/- 26 msec) than that in Group I (60 +/- 6 msec) and Group II (63 +/- 12 msec). Tc was prolonged in proportion to the extent of RWMA during the control period. Immediately after right atrial pacing, Tc was markedly prolonged in Group IIa (from 61 +/- 12 to 90 +/- 20 msec, p less than 0.001) and in Group IIIa (from 73 +/- 26 to 95 +/- 34 msec, p less than 0.001). The post-pacing prolongation of Tc was closely correlated with the extent of post-pacing RWMA. From these results, it is postulated that RWMA may play an important role as a causes of the altered LV relaxation in CADpts.