Pericardial adhesions subject patients requiring cardiac reoperation to potential injuries of the heart, great vessels, and extracardiac grafts during resternotomy. We evaluated polyvinylpyrrolidone (PVP) and a methlycellulose derivative (MCD) as intraoperative irrigating solutions in the prevention of postoperative pericardial adhesions. Fifteen dogs weighing 15 to 20 kg were divided into three equal cohorts and subjected to left thoracotomy with pericardiotomy. Prior to surgical manipulation, the pericardial cavity was irrigated with either PVP, MCD, or Ringer's lactate (RL). Serosal injury stimulating intraoperative trauma was induced by gauze sponge abrasion of the epicardium and inner surface of the pericardium and by allowing desiccation of serosal surfaces for 30 min. The pericardial cavity was evaluated for adhesion formation 6 weeks postoperatively by reoperation. Two independent observers, unaware of the study solution, evaluated the extent and severity of pericardial adhesions on a 0-4 scale. All dogs in the RL control group had surgically significant adhesions and a mean adhesion score of 3.2 +/- 1.1. In contrast, no PVP- or MCD-treated dog had surgically significant adhesions. The mean adhesion scores were 0.2 +/- 0.4 for PVP and 0.5 +/- 0.7 for MCD. Our results indicate that PVP (P less than 0.004) and MCD (P less than 0.024) significantly reduce pericardial adhesion formation when compared to RL. Clinical application of PVP or MCD for the prevention of pericardial adhesions should reduce morbidity and mortality of cardiac reoperation.