Regional myocardial function in the presence of coronary artery stenosis and inotropic intervention: a case for myocardial hibernation?

Abstract

The aim of this study was to examine the effect of an inotropic intervention on regional myocardial function in the presence of a significant stenosis in a coronary artery. During 0.5% halothane anesthesia, intravenous dobutamine (2.5 and 5 micrograms.kg-1.min-1) was administered to eight pigs. A critical constriction was applied to the left anterior descending (LAD) coronary artery and regional myocardial function was determined with the end-systolic pressure-length relationship in the area of distribution of the LAD and left circumflex coronary artery. Infusion of dobutamine was associated with an increase in the end-systolic pressure-length relationship in the left circumflex coronary artery region from 31.81 +/- 7.87 to 81.03 +/- 21.43 mm Hg.mm-1 (X +/- SEM, P = 0.005), whereas function in the LAD coronary artery region did not change significantly (21.78 +/- 3.97 to 21.97 +/- 6.91 mm Hg.mm-1, P = 0.124). Regional stroke work in the left circumflex coronary artery distribution area increased from 124.38 +/- 24.04 to 222.00 +/- 37.83 mm Hg.mm during the administration of 5 micrograms.kg-1.min-1 dobutamine (P = 0.0125). In the LAD coronary artery area, regional stroke work remained at baseline values. Once the constriction was released, the end-systolic pressure-length relationship in the LAD artery segment increased from 21.97 +/- 2.45 to 35.36 +/- 4.55 mm Hg.mm-1 (P = 0.121). These results suggest that hibernation develops in the myocardial segment supplied by a stenotic coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)