Optimal access to the rat heart by transverse bilateral thoracotomy with double ligature of the internal thoracic arteries.

Rats are used widely in ischemia-reperfusion and other heart experiments, but current protocols for thoracotomy have serious shortcomings. Median sternotomy causes bleeding from sternum itself and the internal thoracic arteries, whereas left thoracotomy requires exteriorization of the heart and its reintroduction after completion of the procedure and often is complicated by traction or torsion of the cardiopulmonary bundle and atelectasis in the left lung. Here we describe a new, terminal procedure that minimizes blood loss and allows wide access to the heart without disturbing its anatomic position. Transverse thoracotomy, preferably through the fifth intercostal space, is performed after double ligature of both internal thoracic arteries 1 intercostal space above and 1 below the incision. Blood loss is minimal and occurs mainly with dissection of deep pectoral muscles and intercostal muscles, and the animal is better ventilated than with conventional protocols. We believe that our procedure is superior to existing techniques because it minimizes blood loss during intervention, does not disturb the anatomic position of the heart, and allows wide access to the organ for experimental manipulation.