DO HALOGENATED ANESTHETICS PROTECT FROM I SCHEMIA AND REPERFUSION RELATED MYOCARDIAL LESIONS

Ischaemia and reperfusion of the myocardium are associated with cellul ar injuries leading to a decrease of contractile function and the occu rrence of arrhythmias. As reperfusion of an ischaemic heart results in an intracellular overload of calcium, a calcium blocking agent pretre atment has been shown to exert a protective effect. By altering myocar dial calcium fluxes, volatile anesthetics might also protect the myoca rdium from ischaemic damage and reperfusion injuries. A beneficial eff ect of volatile anesthetics on the ischaemic myocardium has been shown in numerous studies. These agents decrease the severity of ischaemia as well as the incidence of reperfusion arrhythmias and improve recove ry of myocardial mechanics during reperfusion. They also preserve myoc ardial energetics and protect from oxygen-derived free radicals injury . However, some studies do not support these protective effects. The w ide discrepancy between the Various protocols might explain the discre pancy of the results. Enflurane and halothane seem to be more efficien t than isoflurane. This cannot only be explained by different cardiova scular effects, but also by a specific effect on myocardial cells. Hal othane and enflurane mainly decrease intracellular calcium availabilit y by a direct effect on sarcoplasmic reticulum, while isoflurane only decreases the transsarcolemnal calcium entry. Enflurane and halothane have more beneficial effects than isoflurane on free radicals induced myocardial injuries. In conclusion, despite a wide diversity between t he different studies, halothane and enflurane have better protective p roperties against ischaemia and reperfusion myocardial injuries than i soflurane.