Long-term heart preservation by intermittent perfusion with crystalloid medium

This study was undertaken to determine whether hearts preserved with intermittent coronary perfusion would recover physiologic function after a prolonged period of hypothermic preservation. Intermittent perfusion is commonly used for cardioplegia, but its efficacy in long-term heart preservation has not yet been demonstrated. Five groups of isolated rat hearts were studied (n = 7 per group): (1) fresh nonpreserved control hearts; (2) hearts preserved with continuous low-pressure perfusion via the aorta; (3) hearts preserved with cycles of 5 minutes of perfusion followed by 25 minutes of nonperfusion; (4) hearts preserved with cycles of 10 minutes of perfusion followed by 25 minutes of nonperfusion; (5) hearts preserved with submersion storage without perfusion. An oxygenated extracellular-type crystalloid medium (oxygen tension = 820 +/- 5 mm Hg) was used as a preservation medium; preservation was for 12 hours. During preservation, the coronary resistance of the intermittent perfusion-preserved hearts increased significantly, and these hearts produced significantly more excess lactate than did hearts in the other two preservation groups. The submersion-stored hearts exhibited no postpreservation ventricular function in an isolated perfused working rat heart system. The poststorage function of the other four groups, which was quantified during a 4-hour, 37 degrees C perfusion period at constant heart rate, indicated that there were no significant group differences with respect to output or energetics (coronary flow, aortic output, cardiac output, myocardial oxygen consumption, and external work efficiency). The intermittent perfusion-preserved hearts had significantly lower postpreservation contractile function (left ventricular systolic pressure, peak rates of left ventricular pressure development and relaxation, peak aortic flow rate, stroke work, and peak power) and higher left ventricular end-diastolic pressure compared with the control group. Although hearts preserved with intermittent perfusion had a loss of contractile function and decreased compliance compared with fresh hearts, after preservation they had better function than did hearts preserved with submersion storage and the same function as hearts preserved with continuous perfusion.