Abstract
BackgroundThe Krebs-Henseleit buffer is the best perfusion solution for isolated mammalian hearts. We hypothesized that a Krebs-Henseleit buffer-based cardioplegic solution might provide better myocardial protection than well-known crystalloid cardioplegic solutions because of its optimal electrolyte and glucose levels, presence of buffer systems, and mild hyperosmolarity.MethodsIsolated Langendorff-perfused rat hearts were subjected to either global ischemia without cardioplegia (controls) or cardioplegic arrest for either 60 or 180 min, followed by 120 min of reperfusion. The modified Krebs-Henseleit buffer-based cardioplegic solution (mKHB) and St. Thomas’ Hospital solution No. 2 (STH2) were studied. During global ischemia, the temperatures of the heart and the cardioplegic solutions were maintained at either 37°C (60 min of ischemia) or 22°C (moderate hypothermia, 180 min of ischemia). Hemodynamic parameters were registered throughout the experiments. The infarct size was determined through histochemical examination.ResultsCardioplegia with the mKHB solution at moderate hypothermia resulted in a minimal infarct size (5 ± 3%) compared to that in the controls and STH2 solution (35 ± 7% and 19 ± 9%, respectively; P < 0.001, for both groups vs. the mKHB group). In contrast to the control and STH2-treated hearts, no ischemic contracture was registered in the mKHB group during the 180-min global ischemia. At normothermia, the infarct sizes were 4 ± 3%, 72 ± 6%, and 70 ± 12% in the mKHB, controls, and STH2 groups, respectively (P < 0.0001). In addition, cardioplegia with mKHB at normothermia prevented ischemic contracture and improved the postischemic functional recovery of the left ventricle (P < 0.001, vs. STH2).ConclusionsThe data suggest that the Krebs-Henseleit buffer-based cardioplegic might be superior to the standard crystalloid solution (STH2).
Highlights
The Krebs-Henseleit buffer is the best perfusion solution for isolated mammalian hearts
Ischemic contracture The dynamics of left ventricular (LV) pressure during global ischemia and cardioplegia in the hypothermia and normothermia series are shown in Figure 1A and B, respectively
The LV pressures during ischemia were significantly higher in the other hypothermic groups than in the modified KrebsHenseleit buffer-based cardioplegic solution (mKHB)-22 group (P < 0.001, Figure 1A)
Summary
The Krebs-Henseleit buffer is the best perfusion solution for isolated mammalian hearts. Myocardial protection against global ischemia-reperfusion injury during open-heart surgery with cardiopulmonary bypass and cardioplegic arrest remains a challenging problem [1]. Despite recent advances, such factors as progressive aging of patients, the occurrence of comorbidities, and preexisting severe myocardial dysfunction require further improvements in intraoperative cardiac protection [2,3]. Given that the Krebs-Henseleit buffer (KHB) is considered the best option for perfusion of the isolated mammalian heart, KHB-based cardioplegia may be an interesting option. A modified KHB with increased potassium (20 mmol/L) and calcium concentrations (0.1–2.5 mmol/L) was used for continuous coronary perfusion of the isolated rat heart for 180 min at 37°C. Minimal myocardial injury was found when the hearts were perfused with a solution containing 1.5 mmol/L calcium
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