cardioplegia

Cardioplegia is the deliberate, temporary paralysis of the heart to facilitate cardiac surgery and protect the myocardium during periods of ischemia caused by aortic cross-clamping and cardiopulmonary bypass. It is achieved by infusing a cardioplegic solution into the coronary circulation, which arrests electrical activity and reduces metabolic demand, helping preserve cellular integrity during surgery.

Solutions used for cardioplegia are broadly categorized as crystalloid or blood-based. Crystalloid formulations are electrolyte-rich solutions that are typically delivered cold (approximately 4–12°C) to further reduce metabolic demands. Blood-based cardioplegia uses a patient’s own blood combined with potassium and other additives, and can be delivered cold or warm depending on the protocol. Common additives include buffering agents (for pH stability), magnesium (to limit calcium influx), and osmotic agents such as mannitol. Some solutions may include lidocaine or other agents to modulate electrical activity.

Delivery methods include antegrade cardioplegia, delivered through the aortic root or coronary ostia, and retrograde cardioplegia, delivered via the coronary sinus. Dosing can be intermittent or a single-dose strategy (as with certain HTK/Custodiol formulations), with top-up doses typically given every 15–20 minutes or as dictated by the surgical plan.

Indications for cardioplegia include most cardiac operations requiring a still operative field, such as coronary artery bypass grafting, valve repair or replacement, and congenital heart surgery. Potential risks include electrolyte disturbances, myocardial stunning, and arrhythmias on reperfusion, but overall cardioplegia remains a central myocardial-protective strategy in modern cardiac surgery.