Mediastinitis-related right ventricular rupture is an unusual but potentially life-threatening complication of cardiac operations. Between January 1981 and December 1990, a total of 10,182 patients underwent heart operations for ischemic, valvular, and congenital heart disease at the Montreal Heart Institute. Forty-eight patients (0.5%) had postoperative mediastinitis necessitating surgical exploration and sternal debridement. The mediastinum was left open for daily irrigation with povidone-iodine and chest reconstruction was postponed. During treatment, seven patients (0.07%) had right ventricular rupture necessitating immediate surgical repair. All had ischemic heart disease before the operation. There were five women and two men, ages ranging from 52 to 65 years (mean 58 +/- 5 years). Surgical repair consisted of autologous patch covered with omentoplasty assisted with cardiopulmonary bypass. Two patients died, one during the operation of massive hemorrhage and the other 10 days after the operation of uncontrolled sepsis. Five patients survived 2 to 29 months (mean 23 +/- 10 months) after right ventricular rupture, with an overall survival of 71%. Obesity was more frequent in the patients with right ventricular rupture and was found to be a significant risk factor (multivariate analysis, p < 0.05, relative risk 3.22). Histologic examination of the right ventricle in the patient who died after a successful repair revealed fatty infiltration of the right ventricular wall. This may have predisposed the patient toward ventricular rupture. In conclusion, right ventricular rupture, an unusual event in heart surgery, is related to open sternal debridement. Favorable outcome of this complication depends on immediate surgical management, autologous repair, and the use of omentoplasty.