[Connection between electrophysiology and cardiac protection].
A diseased myocardium may require protection from further damage (anoxia, ischemia) due to its own mechanical activity and this process involves a complex number of adaptations. The aim of cardioprotection is to decrease either the work of the heart or improve its ability to deliver a normal cardiac output without further myocardial damage. From an electrophysiological point of view, cardioprotection may involve the protection either from an abnormal electrophysiology (e.g., arrhythmias) or from the damage of an abnormal mechanical activity of the myocardium through electrophysiological modifications. Since the action potential is the signal that regulates both duration and frequency of myocardial contraction, its modifications affect the mechanical performance of the heart. In addition, some of ion fluxes across the cell membrane require energy and therefore add to energy requirements of the myocardium. The mechanisms of cardioprotection involve removal of the disease process (e.g., tachycardia, coronary stenosis), reduction in damage (e.g., preconditioning and reperfusion, coronary vasodilators), decrease in demand (e.g., decrease in cardiac output, rate, sympathetic discharge, calcium load, blood pressure), reduced performance (e.g., decreased contraction through shortening of the action potential by the opening of KATP channels in anoxic cells, administration of KATP channel openers, calcium antagonists, cardioplegic solution in bypassed hearts, removal of calcium overload), and remodeling. However, cardioprotection is not a process limited to the heart, in the sense that the work of the heart cannot be reduced independently of the needs of the circulation. In addition, cardioprotection (physiological and pharmacological) includes advantages and disadvantages and may be more or less specific in addressing myocardial dysfunction. Nevertheless, cardioprotection may avoid serious complications (e.g., arrhythmias), slow down the disease process, and improve the heart function enough to allow more demanding treatments (e.g., surgical interventions).
Vassalle
M
M
Department of Physiology and Pharmacology, State University of New York, Health Science Center, Brooklyn 11203, USA. mvassalle@netmail.hscbklyn.edu
D000200:Action Potentials; D004594:Electrophysiology; D006321:Heart / Q000502:physiology*; D006331:Heart Diseases / Q000517:prevention & control*; D006801:Humans
Rapporti tra elettrofisiologia e cardioprotezione.