Pharmacologically Induced Myocardial Protection During Cardiac Surgery
Both β-adrenergic receptor blockers and calcium channel blockers, when used alongside other methods, have been incorporated into myocardial management strategies by various groups. Calcium channel blockers such as verapamil and diltiazem are particularly beneficial due to their ability to prevent calcium entry into cells and their coronary vasodilatory effects. However, these drugs are also strong negative inotropes and cause prolonged electromechanical inactivity, especially when used in cardioplegic solutions.
Lidoflazine has shown notably positive results when administered intravenously just before cardiopulmonary bypass (CPB) and combined with moderately hypothermic intermittent cardiac ischemia. Lidoflazine is thought to inhibit nucleotide transport, leading to increased myocardial accumulation of endogenous adenosine during ischemia, enhanced lactate extraction during reperfusion, and improved post-ischemic function. Its mechanism of action is complex and distinct from that of β-blockers and calcium channel blockers.
Experimental studies have indicated that certain drugs can reduce reperfusion damage associated with oxygen-derived free radicals. However, in the context of blood cardioplegia and pressure-controlled, initially hyperkalemic blood reperfusion, incorporating free radical scavengers has not been shown to offer additional protection.
