INTRAVENOUS LIPID INFUSION RESULTS IN MYOCARDIAL LIPID DROPLET ACCUMULATION COMBINED WITH REDUCED MYOCARDIAL PERFORMANCE IN HEPARINIZED RABBITS

The question addressed in this study was whether a relation between my ocardial lipid droplet accumulation and depressed myocardial function existed following intralipid infusion for 45 min in open chest, anaest hetized rabbits. One group of rabbits (n = 8) received intralipid infu sion whereas a control group (n = 8) received sodium chloride. Local m yocardial performance was obtained by sonomicrometry and the fractiona l volume of myocardial lipid droplets was measured by morphometric met hods. The fractional volume of lipid droplets was 0.667 +/- 0.116% in the intralipid group compared with 0.318 +/- 0.080% in the control gro up (P < 0.03). Cardiac output and stroke volume fell 26% (P < 0.0001) and 34% (P < 0.0001), respectively, as a result of intralipid infusion . However, myocardial blood flow obtained by radiolabelled microsphere s remained unchanged. Local myocardial function was reduced for both s egments after intralipid infusion; maximal systolic shortening was red uced from 15.63 +/- 1.45 to 12.07 +/- 1.55% (P < 0.002) in the circumf erential segment and from 9.46 +/- 1.17 to 7.40 +/- 0.53 % (P < 0.05) in the longitudinal segment. The end-diastolic length of the circumfer ential segment was reduced by 3% (P < 0.05) after intralipid infusion. The reduced end-diastolic length of circumferential segments together with unchanged left ventricular end-diastolic pressure might indicate reduced left ventricular end-diastolic compliance. We conclude that a cute intralipid infusion in rabbits results in myocardial lipid drople t accumulation and depressed local myocardial function.