View clinical trials related to Myocardial Stunning.
Filter by:This study aims to confirm the safety and efficacy of diazoxide as an additive to hyperkalemic cardioplegia in patients undergoing cardiac surgery with cardiopulmonary bypass. The investigators hypothesize that diazoxide combined with hyperkalemic cardioplegia provides superior myocardial protection and reduced myocardial stunning compared with standard cardioplegia alone. The investigators will randomize 30 patients in a 2:1 fashion to treatment vs control. Safety will be assessed by comparing mean arterial blood pressure measurements, glucose levels and incidence of adverse events between the two groups. Efficacy will be assessed by comparing right and left ventricular function in pre-operative vs post-operative transesophageal echocardiograms, need for mechanical circulatory support, ease of separation from bypass and Vasoactive Inotrope Score (VIS) between the two groups. The information gained could pave the way for the use of Katp (Potassium-atp) channel openers to prevent stunning, improve patient outcomes, and reduce health care costs related to myocardial stunning that requires inotropic and mechanical support following cardiac surgery.
The rational of the study is the description of the evolution of systolic cardiac function post-stunning, evaluated by transesophageal minimally invasive echocardiography (hTEE). The uses of these non-invasive methods have proved to be accurate for the qualitative and semi-quantitative determination of the contractile function of the left ventricle and the volume status of the patient. Furthermore the use of this technique has been demonstrated to be a reliable method to analyze the stunning recovery infarction after controlled cardiac arrest during the extra-corporeal circulation.
Despite surgical and medical innovation have reduced mortality rates in cardiac surgery, the disease severity and operative procedural complexity have increased and morbidity rate is still high. Ischemia-reperfusion (I/R) injury, redefined in cardiac surgery "post-cardioplegic injury" (2) as a whole of ischemia-reperfusion, cardiopulmonary bypass and surgical trauma, has been recognized as a significant contributor to mortality and morbidity. I/R injury is classified as reversible or irreversible. Reversible injury includes arrhythmias, edema, vascular dysfunction and contractile stunning expressed as low output syndrome without cell death and without apparent signs of infarction or other serum injury markers. Irreversible reperfusion injury includes apoptosis and necrosis. I/R injury is a complex process associated with increase of radical, oxidant and cytokines production, complement and neutrophil activation and endothelial activation leading to microvascular dysfunction and deterioration of coronary flow reserve. In the hypoxic heart increase anaerobic lactate production, K+ efflux and membrane depolarization. The intracellular Na+ concentration rises as a consequence of slow Na+ channels inactivation and the induction of voltage-gated Na+ channel late current component (late INA). Intracellular Na++ accumulation enhanced activity of reversed-mode Na+-Ca++ exchanger causing intracellular Ca++ overload and ventricular dysfunction. Therefore inhibition of late INA has been shown to be cardioprotective. Ranolazine, an FDA-approval antianginal and anti-ischemic agent, high selective blocker of late INA, inhibits the late sodium current in myocardial ischemia, decreases Na+ and Ca2+ overload and improves left ventricular function in experimental animal models. For this reason it was also adjuncted to cardioplegia improving diastolic function in isolate Langerdoff-perfused rat hearts. The authors test the hypothesis that ranolazine improve myocardical protection in patients undergoing coronary artery surgery with cardiopulmonary by-pass (CPB).