Parenteral hyperalimentation with long chain triglycerides (LCT) during reperfusion improves recovery from regional myocardial stunning in chronically instrumented dogs

Abstract

Numerous investigations have been performed to elucidate the pathophysiological mechanism of myocardial stunning [1,2]. Free Fatty Acids (FFA) are the primary source of high energy phosphates for the myocardium under aerobic conditions. Increasing FFA during hypoxia or ischaemia, reduces myocardial function [3]. Jones et al. described an improvement in canine myocardial performance after ischaemic cardiac arrest when triglycerides (Intralipid 10%) were given during reperfusion [4]. We investigated the effects of a 20% LCT emulsion on regional stunning administered during reperfusion in the conscious dog. Seven mongrel dogs were chronically instrumented for the measurement of heart rate (HR), aortic (ABP), left atrial (LAP) and left ventricular pressure (LVP) and its first derivative LVdP/dt, blood flow velocity through the left anterior descending (FLad) and left circumflex (FCx) coronary arteries and regional myocardial wall thickening in the areas perfused by the LAD and Cx (WTlad and WTCx). A hydraulic occluder was positioned around the LAD. Using a cross over design all animals received ten minutes of ischaemia in the LAD area with and without the LCT emulsion during reperfusion. The LCT emulsion was given i.v. over 30 min as a continuous infusion of 7 mL kg−1. The infusion was started 15 min after reperfusion. Full heparinisation was accomplished by i.v. administration heparin using 200 IU kg−1. Results were analysed using repeated measures ANOVA and a paired t-test. In the LCT group, recovery from regional myocardial stunning in the LAD area improved, compared with the control (no LCT) group (Fig. 3). However, complete recovery of regional myocardial function was accomplished after 24 h in both groups. In the LCT group LVdP/dt max increased significantly from 2175 ± 139 at baseline to 2500 ± 233 mmHg sec−1 (P<0.05) while dP/dt max was not changed in the control group. During ischaemia FCx increased. All other parmeters remained stable throughout the study and no differences between the two groups were observed.Fig. 3: (abstract 3). Regional myocardial performance in the LAD perfused area with and without a LCT emulsion, before, during and after 10 min of ischaemia. Data are presented as a mean ± sem.* P<0.05 vs. baseline. ** P<0.05 vs. control. n=7. b: baseline. i: ischaemia.We conclude that i.v. administration of LCT during reperfusion after brief ischaemia, improves recovery from regional myocardial stunning. Further investigations with respect to mechanism of action and possible therapeutic exploitation of these findings appear worthwhile.