CORRELATION BETWEEN POST-EJECTION SHORTENING AND IMPROVEMENT IN REGIONAL WALL-MOTION AFTER REVASCULARIZATION IN PATIENTS WITH CORONARY-ARTERY DISEASE

This study investigates the relationship between regional post-ejectio n shortening and improvement in wall motion after revascularization in patients with severe regional left ventricular contractile dysfunctio n. Canine studies have documented the phenomenon of post-systolic shor tening during acute ischemia, and this predicted recovery of contracti le function when ischemia was relieved. This delayed shortening from t he ischemic segment would cause regional emptying while the other norm al portion of the left ventricle starts to have diastolic relaxation. This was detectable by standard phase analysis of the radionuclide ven triculogram, the abnormal region with delayed emptying being distingui shed from the normal portion of left ventricle as an area with a homog eneous phase delay. Twelve patients with successful revascularization and a pre-operative study demonstrating a single homogeneous area of p hase delay were identified. The area was demarcated and the regional v olume-time curve constructed. The volume-time curve of the abnormal re gion is analogous to the myocardial segment length versus time relatio nship in the canine model. We quantitated the amount of delayed (post- systolic) emptying in the demarcated region as the difference between end-systole counts and post-systolic nadir counts, and this was normal ised to left ventricular stroke count. After revascularization, region al ejection fraction improved from 44 +/- 10% to 62 +/- 14% (P < 0.001 ), representing a 47 +/- 50% improvement over baseline. The percentage improvement in regional ejection fraction cell-elated with post-systo lic emptying (r = 0.74, P < 0.05) but not with initial regional ejecti on fraction. In conclusion, post-ejection shortening causes regional p ost-systolic emptying and this correlates with post-revascularization improvement in regional wall motion.