Right Ventricle is Protected Better by Warm Continuous than by Cold Intermittent Retrograde Blood Cardioplegia in Patients with Obstructed Right Coronary Artery

Abstract

Preservation of the right-ventricular (RV) myocardium is a ciinical challenge especially in patients with occluded right coronary artery, in whom antegrade cardioplegia cannot reach areas distal to the Stenosis. Retrograde administration of cardioplegia has been thought to overcome the problem, but it has been blamed for inadeguate distribution to the RV and possibly poorer functional recovery of this ventricle. Adapting the hypothesis that warm blood cardioplegia may offer better distribution and a more effective supply of oxygen to the arrested heart, we compared RV function in a randomised trial in patients with significant right and left coronary artery disease, after either warm continuous (warm group, n = 15) or intermittent cold (cold group, n = 14) retrograde blood cardioplegia. Right-ventricular function was assessed by determining the ejection fraction (fast-response thermodilution) and preload-related RV stroke work in repeated measurements. The RV ejection fraction remained steady in the warm group during the postoperative course, while it declined significantly in the cold group after Operation and differed from that in the warm group until the second postoperative day (p < 0.05 - 0.001). The ratio of RV stroke work to right atrial pressure was greater postoperatively in the warm than in the cold group until 6 hours after cardiopulmonary bypass (p < 0.05-0.01). Creatine kinase cardiac isoenzyme release was greater in the cold group (p < 0.01). The reiationship between left-ventricular stroke work and corresponding preload did not differ between the groups. It can be concluded that recovery of RV function after coronary surgery was better in terms of ejection fraction and preload-related stroke work with warm continuous cardioplegia than with intermittent cold cardioplegia, this along with lower cardiac enzyme release suggesting better RV protection.

Key words

Right-ventricular function - Warm retrograde cardioplegia - Myocardial protection - Coronary artery bypass surgery