Lipid peroxidation results in compromised functional recovery of isolated rabbit hearts after low-pressure, hypothermic, perfused preservation for 24 hours.

Low-pressure, hypothermic perfusion of isolated rabbit hearts for 24 hours compromises contractile function. This occurs despite continuous recirculation of an oxygenated solution. This investigation tested the hypothesis that such functional impairment results from irreversible tissue damage consequent to ischemia-induced lipid peroxidation. Decreases in coronary flow were measured during preservation and related to concentrations of thiobarbituric acid reactive species (TBA+, primarily malondialdehyde, a by-product of lipid peroxidation) in the tissue after preservation. The concentration of TBA+ species and the percent decrease in coronary flow rates at 30 minutes and 24 hours were positively correlated (r = 0.591 and r = 0.646, respectively). India ink was used as a marker of microvascular perfusion. Hearts showing the greatest magnitude of ischemia (evidenced by decreased percentages of perfused microvessels) had the highest levels of TBA+ species (r = 0.924). Moreover, hearts that had the highest levels of TBA+ species in the tissue exhibited the lowest levels of left ventricular function (as measured on a modified Langendorff apparatus; r = 0.767). We conclude that impaired coronary flow rates during perfused preservation portend compromised myocardial contractility. Furthermore, these changes occur largely within the first 30 minutes of perfusion. It is likely that early decrements in microvascular perfusion and consequent tissue injury owing to lipid peroxidation underlie impaired myocardial function after preservation.