BACKGROUND The combined method of cold storage and coronary perfusion for prolonged preservation of donor hearts was evaluated through preservation and transplantation with the use of 10 pair of adult mongrel dogs. METHODS In situ initial flush for cooling and coronary vascular washout was performed with a University of Wisconsin solution. The heart was then removed and immersed into a cold (4degrees C) University of Wisconsin solution. After 12-hour cold storage, 1-hour preservation was added by coronary perfusion using a 4degree C oxygenated University of Wisconsin solution. High-energy phosphate (phosphocreatine, beta-adenosine triphosphate) and phosphate were measured by 31P-nuclear magnetic resonance spectroscopy at 0-hour cold storage, 12-hour cold storage, and immediately after coronary perfusion. RESULTS Phosphocreatine and beta-adenosine triphosphate decreased to 12.1 +/- 24.2% (mean +/ standard deviation), 37.4% +/- 25.0%, respectively, after 12-hour cold storage, and significantly increased to 94.0% +/- 48.7% (p < 0.001), 48.8% (p < 0.05), respectively after 1-hour coronary perfusion. Disorder of nuclear arrangement and edema of muscular cells, which were observed after cold storage, were histologically restored after 1-hour coronary perfusion. After transplantation of preserved grafts, left ventricular pressure and left ventricular rate of pressure rise were evaluated in the graft with 12-hour cold storage only (group A) and in the graft with 12-hour cold storage and 1-hour coronary perfusion (group B). Left ventricular pressure 2 hours after transplantation in group B recovered to 76.1% significantly (p < 0.01), compared with 51.9% in group A. Significantly higher values of left ventricular rate of pressure rise 2 hours after transplantation was observed in group B (83.0% +/ 12.7%) compared with group A (68.2% +/- 12.5%). CONCLUSIONS These results indicate that the combined method of cold storage and coronary perfusion may be effective for myocardial protection during long-term preservation.