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[Do halogenated anesthetics protect from ischemic and reperfusion myocardial injuries?]
1Département d'Anesthésie-Réanimation, Hôpital du Bocage, Dijon.
Insights
Volatile anesthetics like enflurane and halothane protect the heart from ischaemia and reperfusion injuries by managing intracellular calcium. These agents offer better myocardial protection than isoflurane, reducing arrhythmias and improving recovery.
Area of Science:
- Cardiology
- Anesthesiology
- Cellular Biology
Background:
- Myocardial ischaemia and reperfusion cause cellular injury, leading to reduced contractile function and arrhythmias.
- Intracellular calcium overload during reperfusion is a key factor in myocardial damage.
- Calcium channel blockers are known to protect the myocardium, suggesting calcium flux modulation is crucial.
Purpose of the Study:
- To investigate the protective effects of volatile anesthetics on myocardial ischaemia and reperfusion injuries.
- To compare the efficacy of different volatile anesthetics (enflurane, halothane, isoflurane) in protecting the myocardium.
- To elucidate the mechanisms underlying the cardioprotective effects of volatile anesthetics.
Main Methods:
- Review of existing studies on volatile anesthetics and myocardial ischaemia/reperfusion.
- Analysis of data regarding contractile function, arrhythmias, myocardial energetics, and free radical injury.
- Comparison of the effects of enflurane, halothane, and isoflurane on myocardial calcium handling.
Main Results:
- Volatile anesthetics generally decrease ischaemia severity, reduce reperfusion arrhythmias, and improve myocardial mechanical recovery.
- Enflurane and halothane demonstrate greater protective effects than isoflurane.
- Halothane and enflurane primarily reduce intracellular calcium by affecting the sarcoplasmic reticulum, while isoflurane mainly affects trans-sarcolemmal calcium entry.
Conclusions:
- Despite variability in study protocols, enflurane and halothane offer superior protection against myocardial ischaemia and reperfusion injuries compared to isoflurane.
- The differential effects are likely due to distinct mechanisms of action on myocardial calcium availability and free radical defence.
- Volatile anesthetics represent a potential therapeutic strategy for mitigating myocardial damage during ischaemic events.
Abstract:
Ischaemia and reperfusion of the myocardium are associated with cellular injuries leading to a decrease of contractile function and the occurrence of arrhythmias. As reperfusion of an ischaemic heart results in an intracellular overload of calcium, a calcium blocking agent pretreatment has been shown to exert a protective effect. By altering myocardial calcium fluxes, volatile anesthetics might also protect the myocardium from ischaemic damage and reperfusion injuries. A beneficial effect 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 recovery of myocardial mechanics during reperfusion. They also preserve myocardial energetics and protect from oxygen-derived free radicals injury. However, some studies do not support these protective effects. The wide discrepancy between the various protocols might explain the discrepancy of the results. Enflurane and halothane seem to be more efficient than isoflurane. This cannot only be explained by different cardiovascular effects, but also by a specific effect on myocardial cells. Halothane and enflurane mainly decrease intracellular calcium availability 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 the different studies, halothane and enflurane have better protective properties against ischaemia and reperfusion myocardial injuries than isoflurane.