 From November 2006 to February 2009, 80 consecutive patients undergoing elective aortic valve replacement at Ullevål University Hospital, Oslo, Norway, volunteered to participate, and were included in the study. All patients gave their written consent. The local ethical committee approved the study protocol. Eligible for operation were patients with a mean aortic valve gradient 50 mmHg or aortic valve area 0.7 cm2 or symptomatic aortic valve stenosis. Before induction of anesthesia, at the same day as the operation, patients were randomly allocated to one of two groups, either receiving cold 4-8C crystalloid or cold 4-8C blood cardioplegia. The randomisation was performed by opening of sealed envelopes and every cohort of ten patients was block-randomized five crystalloid and five blood to ensure an even distribution of the two cardioplegia regimen with time. Although cardioplegia is frequently given retrogradely through the coronary sinus, this procedure might give an inadequate protection of the right ventricle unless combined with antegrade administration of cardioplegia through the right coronary ostium. For the sake of simplicity, in the present study, cardioplegia was delivered antegradely only through the coronary ostia strictly every 20 min with a pressure of 300 mmHg with a Stöckert roller pump Stöckert Instrumente GmbH, Munich, Germany, throughout the period of aortic cross-clamping. Initially, 400 ml of cardioplegia was administrated immediately following asystole. Every 20 min, 300-400 ml was administrated into the left coronary ostium and 200-300 ml into the right coronary ostium, taking the size of the heart into consideration. Patients with significant coronary artery stenoses 50 or other significant concomitant heart valve disease were excluded from the study. Ten patients were also excluded from the study after randomisation five patients in each group for the following reasons: In the group receiving blood cardioplegia four patients were excluded because they needed additional cardioplegia because of emergence of spontaneous heart rhythm after 10-12 min before that scheduled by the protocol. One patient was excluded because the heart did not stop and the surgeon decided to open the aorta and administer cardioplegia directly into the coronary ostia. In the group receiving crystalloid cardioplegia two patients were excluded because they needed additional cardioplegia because of emergence of spontaneous heart rhythm after 10-13 min before that scheduled by the protocol. Two patients were excluded because the heart did not stop initially and the surgeon decided to open the aorta and administer cardioplegia directly into the coronary ostia. One patient was excluded because the second shot of cardioplegia was given 30 min after the first and not 20 min as decided by the protocol. 