Twenty-four-hour intermittent perfusion storage of the isolated rat heart. II. Perfusion pressure and functional preservation.

This study investigated the effect of intermittent perfusion (IP) pressures on functional preservation of the cold-stored isolated rat heart. The heart was flushed with cardioplegic solution #11 with ethylene diamine-tetraacetic acid and 2, 3-butanedione monoxime (CP-11EB), and stored at 0 degree C for 24 hr. During storage, the heart was intermittently perfused for 3 min at 10 and 17 hr of storage with 25 degrees C oxygenated CP-11EB. The IP pressures studied were: 20, 30, 40, 50, 60, 70, 80, and 100 mm Hg. Poststorage recovery of function was assessed with 30 min of working reperfusion. Control function of the unstored heart was: aortic flow (AF), 51.3 +/- 2.2 ml/min; coronary flow (CF), 25.8 +/- 1.2 ml/min; cardiac output (CO), 77.7 +/- 2.3 ml/min; work, 92.0 +/- 4.9 g-m/min; and coronary vascular resistance (CVR), 2.64 +/- .21 mm Hg-min/ml. Functional return in the 30,40,50,60,70, and 80 mm Hg groups was similar. Recovery in a representative group (60 mm Hg) was: AF, 52 +/- 3%; CF, 41 +/- 2%; CO, 48 +/- 3%; work, 42 +/- 3%; and CVR, 225 +/- 10% of the control. The total IP volume in this group was 71.0 +/- 1.7 ml; total lactate dehydrogenase (LDH) release during IP was 8.62 +/- .37 units/g dry; and end-storage tissue lactate was 52.6 +/- 6.4 mumole/g dry. As IP pressure decreased to 20 mm Hg, cardiac functional recovery declined significantly to AF, 35 +/- 6%; CF, 33 +/- 2%; CO, 34 +/- 5%; and work, 27 = 4% of control (P < .05 vs. 60 mm Hg group). The total IP volume decreased to 10.1 +/- .9 ml, tissue lactate content rose to 87.1 +/- 10.9 (P < .05 vs. 60 mm Hg group), but LDH release fell to 5.59 +/- .46 (P < .05 vs. 60 and 100 mm Hg groups). When IP pressure increased to 100 mm Hg, cardiac function was depressed with AF recovered to 25 +/- 3%; CF, 30 +/- 3%; CO, 26 +/- 3%; work, 21 +/- 3%; and CVR, 294 +/- 26% of control (P < .05 vs. 60 mm Hg group). IP volume increased to 100.7 +/- 2.4 ml; total LDH release increased to 19.1 +/- 1.2 (P < .05 vs. 60 mm Hg group), although tissue lactate (58.9 +/- 3.9) was not different from the 60 mm Hg group. End-storage tissue wet/dry weight ratio and myocardial adenosine triphosphate content were not different among the 20, 60, and 100 mm Hg groups. In conclusion, IP has a broad pressure optimum ranging from 30 to 80 mm Hg for 24-hr hypothermic preservation of the rat cardiac explant.