Augmented right heart cooling (RHC) with bicaval cannulation, pulmonary artery venting, and intracavitary cooling has been advocated for prevention of right ventricular failure and supraventricular tachyarrhythmias after open heart surgery. To evaluate RHC, 78 patients undergoing coronary bypass surgery were prospectively randomized to receive added RHC (n = 38) or standard protection with single atrial cannulation (SC) (n = 40). RHC and SC patients were similar regarding right coronary artery occlusion (n = 10 and 12, respectively), number of grafts performed (3.7 +/- 1.0 and 3.4 +/- 0.9), and cross-clamp time per graft (10.2 +/- 1.8 and 9.8 +/- 2.3 minutes). RHC led to significantly lower right atrial (11.6 degrees +/- 1.0 degree vs. 19.5 degrees +/- 3.3 degrees C) and right ventricular (7.2 degrees +/- 1.9 degrees vs. 12.2 degrees +/- 1.9 degrees C) temperatures. There was no detectable deterioration in right heart function or left heart function in either group after cardiopulmonary bypass. Bypass time was longer in RHC patients (86.7 +/- 17.9 vs. 76.0 +/- 18.2 minutes, p less than 0.05). Technical problems related to multiple cannulation occurred in four RHC patients. After cross-clamp removal, creatine kinase-MB levels were significantly higher with RHC at 2 hours (14.2 +/- 7.6 vs. 6.4 +/- 4.6 IU/l, p less than 0.001), 12 hours (19.1 +/- 19.5 vs. 8.6 +/- 10.3 IU/l, p less than 0.005), and 24 hours (14.1 +/- 19.6 vs. 7.1 +/- 9.2 IU/l, p less than 0.05). Mortality and morbidity were similar in the two groups. In particular, supraventricular tachyarrythmias occurred in 11 (28.9%) RHC and 10 (25%) SC patients.(ABSTRACT TRUNCATED AT 250 WORDS)