| Abstract: | Two commercially available formulations of St. Thomas' Hospital cardioplegic solutions, known as No. 1 (MacCarthy) and No. 2 (Plegisol, Abbott Laboratories, North Chicago, Ill.), were compared in the isolated working rat heart subjected to a long period (3 hours) of hypothermic ischemic arrest with multidose infusion. Solution No. 2 was found to be superior in nearly all respects. Of the 10 hearts infused with solution No. 1, persistent ventricular fibrillation during postischemic reperfusion occurred in six. Two of the six hearts, still in fibrillation after 15 minutes of reperfusion, were returned to regular rhythm by electrical defibrillation but failed to maintain an output. In contrast, in the 10 hearts infused with solution No. 2, ventricular fibrillation was short lasting (p less than 0.01). In comparing mechanical function in all hearts returning to regular rhythm (either spontaneously or after electrical defibrillation), the mean postischemic recoveries for aortic flow and rate of rise of left ventricular pressure (expressed as a percentage of its preischemic control) were significantly greater with solution No. 2 than with solution No. 1 (74.3% +/- 6.9% compared with 18.7% +/- 8.9%, p less than 0.01, and 98.0% +/- 6.0% compared with 63.0% +/- 9.0%, p less than 0.005, respectively). Creatine kinase leakage tended to be lower in hearts infused with solution No. 2 (19.7 +/- 4.7 IU/15 min/gm dry weight as opposed to 27.5 +/- 4.7 IU/15 min/gm dry weight), although this difference did not achieve a level of statistical significance. Consideration is given to the differences in formulation between solutions, which might account for the improved performance with solution No. 2, and it is concluded that the lower calcium content of solution No. 2 (1.2 as opposed to 2.4 mmol/L) is likely to be the most important factor. |
