Interventions
electromechanical arrest of the heart
STERILE
Participants received either IWBC (blood cardioplegia at the same temperature as the body, ≥34°C) or ICBC (blood cardioplegia at 4–6°C) during surgery.The route of cardioplegia infusion for both groups was usually into the aortic root, or selectively into the coronary arteries. All surgeons used the same established cardioplegia protocols based around St Thomas’ solution.For ICBC, cardioplegic concentrate solution (Harefield Hospital Formulation, Terumo BCT Ltd) was mixed with arterialized patient blood drawn from the oxygenator, in a 1:4 ratio, to give a concentration of 24 mM KFor IWBC, the cardioplegic concentrate (Martindale sterile concentration for cardioplegia infusion) was added to arterialized patient blood via a syringe driver to achieve a concentration of 17.5 mM K+, initial infusion and reinjection rates were based on body surface area. The flow was 1–1.5 times the physiologic coronary flow (estimated at 5% of cardiac output). The arresting dose of cardioplegia was given for 1 min after electromechanical arrest of the heart. Reinjections at two-thirds of the initial injection speed were given for 1 min every 15 min during aortic cross-clamping (see 