Prolonged myocardial protection with St. Thomas' Hospital solution and University of Wisconsin solution. The importance of preservation techniques.

The effectiveness of University of Wisconsin solution (UWS) and oxygenated St. Thomas' Hospital solution (STS) for prolonged myocardial protection was evaluated in isolated working rat hearts preserved for 12 h at 4 degrees C using three different preservation techniques: induction of cardiac arrest and subsequent hypothermic storage with STS (group 1, n = 9) or UWS (group 4, n = 9), intermittent coronary flush (every 90 min) with STS (group 2, n = 9) or UWS (group 5, n = 9), or continuous coronary perfusion with STS (group 2, n = 7) or UWS (group 6, n = 7) before 60 min of reperfusion. In the UWS preserved hearts, recovery of aortic flow was greater when the simple storage technique was employed compared to intermittent or continuous coronary perfusion (groups 5 and 6). In the STS preserved hearts, aortic flow recovery was superior when the intermittent perfusion technique was applied. The same pattern was observed with regard to recovery of left ventricular pressure. Lactate dehydrogenase release during reperfusion was significantly less pronounced in group 4 (UWS, single flush, simple storage) as compared to group 1 (STS, single flush and simple storage), whereas best preservation of myocardial high energy phosphates was observed when hearts were preserved with multiple dose cardioplegia using STS. Simple hypothermic storage with UWS affords the best functional recovery after prolonged myocardial ischemia in all groups. Repetitive or continuous application of this solution is detrimental, possibly due to potassium overloading. In STS treated groups, multiple dose application of oxygenated STS enhances functional and metabolic recovery compared to its single dose application.(ABSTRACT TRUNCATED AT 250 WORDS)