Effect of melatonin in the prevention of postoperative pericardial adhesion formation.

To evaluate the efficacy of melatonin in preventing postoperative pericardial adhesions, 12 single breed dogs were randomized equally into experimental (melatonin) and control groups. After ketamine anesthesia, a vertical midsternal incision was done and the parietal pericardium of the inferior site of the heart was opened vertically. To promote adhesion formation, abrasions were created on both parietal and visceral pericardial surfaces in an area of 2 cm2 with two vertically reciprocal movements of dry gauze. In the melatonin group, 5% ethanol plus 10 mg/kg melatonin in 10 ml NaCl and, in control group, 10 ml NaCl dilution vehicle containing 5% ethanol was instilled intra-pericardium on to the abrasion sites. After a 6-week recovery period, the animals were evaluated for grading of adhesion formation by an examiner blinded to the groups. The extent of adhesions was graded from 0 (no adhesion) to 3 (total involvement of the traumatized area). The results showed that adhesion scores were significantly lower in melatonin group (1.00+/-0.63) compared with controls (2.66+/-0.51); P=0.001. We conclude that melatonin administration effectively reduced postoperative pericardial adhesions in dogs. The use of melatonin in the prevention of pericardial adhesion formation in human subjects warrants further investigations.