Abstract
Myocardial contractile function after cardioplegic arrest is often depressed and an ideal cardioplegic solution has not been developed yet. The aim of this study was to assess the efficacy of phosphodiesterase III inhibitors, amrinone and enoximone, and levosimendan, a novel Ca2+ sensitizing agent, on recovery of hearts after normothermic cardioplegic arrest when added to the St. Thomas' hospital cardioplegic solution. In the control group, isolated guinea pig hearts were perfused in Langendorff apparatus and arrested with standard St. Thomas' solution. In other groups, amrinone (10(-5) mol.L-1), levosimendan (10(-5) mol.L-1), or enoximone (10(-4) mol.L-1) were added to the cardioplegic solution. In all hearts, intraventricular pressure, +dp/dtmax, -dp/dtmax, area under pressure-time curve, heart rate, coronary flow, lactate dehydrogenase and creatine kinase enzyme leakage, and oxygen consumption were measured. In the enoximone group, contractility force and +dp/dtmax, were found to be significantly high in the reperfusion and inotropic periods in comparison with other groups (p < 0.05). -dp/dtmax and area under contractility-time curve values were significantly high in inotropic period in enoximone group (p < 0.05). No statistically significant difference was noted in other groups. Cardioplegic solution enrichment with enoximone augmented mechanic functions in reperfusion period. No positive effect of amrinone or levosimendan was observed in this study.
Highlights
Material and MethodsIn patients with poor cardiac function, low cardiac output syndrome is the most serious problem following cardiac surgery
This study is devised to investigate the effects of these drugs to ischemia-reperfusion injury and mechanical dysfunction in reperfusion period, when added to St
All of the hearts arrested within 3 minutes of cardioplegic solution administration and returned spontaneously to sinus rhythm
Summary
In patients with poor cardiac function, low cardiac output syndrome is the most serious problem following cardiac surgery. Many research have been conducted in the field of myocardial protection and different additives to cardioplegic solutions have been tested. It is well documented that enoximone, levosimendan and amrinone improve myocardial contractility after cardiopulmonary bypass and in the postoperative period [2,11]. The role of addition of these drugs to the cardioplegic solutions has not been investigated yet. This study is devised to investigate the effects of these drugs to ischemia-reperfusion injury and mechanical dysfunction in reperfusion period, when added to St. Thomas hospital cardioplegic solution. The hypothesis was that pre-treatment with these drugs might be beneficial as they may store more Ca++ in the sarcoplasmic reticulum before cardiac contractility restarts in the reperfusion period
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