Right ventricular myocardial protection through intracavitary cooling in cardiac operations.

In an attempt to protect the right ventricle, we designed and tested a closed cooling system that circulates cold saline through a double-lumen, balloon-tipped catheter positioned in the right ventricular cavity. Fourteen sheep were randomly assigned to two groups. In group A (n = 7), the right ventricular cooling catheter system was used in addition to coronary cardioplegic perfusion and systemic hypothermia for myocardial protection. Group B (n = 7) served as a control group. In group A, the right ventricular temperatures were significantly lower than those of the control group (16.1 degrees +/- 0.3 degrees C versus 23.9 degrees +/- 0.4 degrees C; p less than 0.0001, Student's t test). The most common temperature range was 12 degrees to 18 degrees C (67.1%, frequency distribution analysis), and 63.2% of temperatures were below 16 degrees C. The catheter system also maintained the temperatures of the interventricular septum at a lower level than those recorded in the control group and prevented septal rewarming, which was significant in group B (from 16.5 degrees +/- 1.5 degrees C to 25.0 degrees +/- 0.9 degrees C; p less than 0.04, Mann-Whitney U test). Left ventricular temperatures were not changed by the catheter system. By better cooling the right ventricle and the septum, the right ventricular cooling catheter system should decrease the prevalence of right ventricular failure and allow more time to safely complete multiple coronary anastomoses in coronary artery bypass graft operations.