The administration of cardioplegia is a core component of the multimodal approach to myocardial protection during cardiac surgery with cardiopulmonary bypass.^1,2 An ideal cardioplegia solution should facilitate rapid cardiac arrest, limit ischemia-reperfusion injury, allow prompt return of normal cardiac function, and have no toxicity.^1,2 Cardioplegia typically causes myocardial arrest by depolarizing (high-potassium approach) or hyperpolarizing (low-electrolyte approach) the cellular membrane.^1–3 Furthermore, the route of administration has evolved to include antegrade delivery and/or retrograde delivery with set flow and pressure ranges to enhance efficacy and safety.^3,4 The family of cardioplegic solutions can be further classified to include considerations such as composition, solvent (blood versus crystalloid), temperature (cold versus warm), and pattern of administration (single shot versus intermittent versus continuous approaches).^5–7

The practice of cardioplegia has evolved to extend the tolerated myocardial ischemic time for a given cardiac operation.^1–3 A spectrum of conduct for cardioplegia has developed over the last two decades that has resulted in excellent outcomes, despite aortic cross-clamp times beyond 120 minutes.^1–3,5,6 In recent years, the application of del Nido cardioplegia has spread from pediatric to adult cardiac surgical practice as a preferred cardioplegic technique, especially in low-risk cases with a normal ejection fractions and an expected myocardial ischemic time below 120 minutes.^8–10 The composition of del Nido cardioplegia includes a crystalloid base with potassium chloride in high concentration to facilitate depolarized arrest of the myocardium.^8,9 The addition of bicarbonate allows for scavenging of excess acid, and the addition of magnesium facilitates calcium channel blockade for enhanced myocardial protection.⁸ Further additives include mannitol to decrease myocardial edema and to scavenge oxygen-free radicals as well as lidocaine for sodium channel blockade to decrease myocardial excitability and metabolism.^8,9

The administration of del Nido cardioplegia also includes oxygenated blood in a 1:4 ratio with a crystalloid base solution.^8,9 In comparison with the current options for blood-based cardioplegias, del Nido cardioplegia provides a longer safe arrest period due in part to the presence of magnesium and lidocaine.^8–10 The experience with del Nido cardioplegia in adult cardiac surgery has resulted in its evolution to become a mainstream option for myocardial protection, especially in cases with a normal ejection fraction and a shorter myocardial ischemic time.^8–10 The ongoing debate is whether the current evidence base is adequate to support its application across the entire spectrum of adult cardiac surgery, including high-risk complex cases that typically have an extended myocardial ischemic time.