Different Effects of Cardioplegic Solution HTK during Single or Intermittent Administration

Abstract

Since intermittent cardioplegic reperfusion during an ischemic period may reduce the ischemic stress of the heart at least by lowering myocardial temperature, we compared the post-ischemic recovery of the dog heart following cardioplegia and subsequent continuous ischemia of 1 X 300 minutes at 22 +/- 1 degree C (model 1) and following cardioplegia and subsequent 3 X 100 minutes of ischemia at 17 +/- 1 degree C with intermittent 4-minute cardioplegic reperfusion every 100 minutes (model 2). The parameters of post-ischemic recovery were the cardiac O2 consumption per beat at work (MVO2-E0): HR), the stability of cardiac rhythm, the left ventricular content of high-energy phosphates, and ultrastructure. Solution HTK with a magnesium concentration of 9 mM/L, in clinical use up to the beginning of 1984, resulted in a significantly better post-ischemic recovery in model 1, despite about 40% lesser ischemic stress in model 2. A reduction of Mg concentration from 9 to 4 mM/l, as in the HTK solution clinically tested since February 1984, did facilitate the post-ischemic recovery in model 1 as indicated by the stability of cardiac rhythm but led to a significant improvement of all parameters of recovery in model 2. Moreover, recovery in model 2 after reduced Mg was also clearly better than in model 1 corresponding to the lesser ischemic stress. The parameters myocardial O2 consumption (MVO2) and potassium loss during HTK perfusion containing 9 and 4 mM/l, respectively, gave indications of specific membrane labilizing effects of Mg in the cardioplegic solution HTK.

Evaluation of Eight Preservation Solutions for Endothelial in situ Preservation

“…HTK was initially developed by Dr Bretschneider as a cardioplegic solution for surgery taking place at temperatures between 23°C and 32°C, similar to those found in the kidney during ISP (24). The large amount of the potent pH buffer, histidine (180 mmol/L), present in HTK, is one possible explanation for the apparently superlative preservation of endothelial structure and function.…”

Intercalated clear cells or pale cells in the sinus node of canine hearts? An ultrastructural study

“…The hearts (n = 3), were fixed by perfusion fixation immediately following cardioplegic coronary perfusion. The HTK solution of Bretschneider was perfused over 11 min at 8°C (Gebhard et al, 1984). The cardioplegic solutions effected an immediate cardiac arrest in diastole.…”

Myocardial Protection and Ischemia Tolerance of the Globally Ischemic Heart

“…On th e othe r hand , it a lso rem oves end pr odu cts of anae robic metabolism, espec ially proton s and la ctate. An incre ase in conce ntrat ion of th ese m etabolites in th e myocardium might oth erwise impair a nae ro bic glycolytic energy gain, and thus possibly also act in terms of sp eeding up the progr ession ofthe ischemic damage (4,7,10). This second criterion is of particular relevance for all cardioplegic soluti on s with relatively low buffer ca pac ity (Tabl e 1).…”