A technique for extracorporeal circulation in the Goettingen minipig allowing recovery and long-term follow-up

The objective of our study was to establish an animal model with extracorporeal circulation (ECC) for investigations on the long-term tolerability of different pericardial substitutes using the Goettingen minipig. A combination of halothane (0.4-0.6% vaporizer setting) in oxygen and nitrous oxide (FiO2 0.33), with the opioid piritramide (75 micrograms/kg/h i.v.) was used for anaesthesia. A muscle relaxant was not administered. Due to the size of the animals (mean body weight 37.6 kg) the operative procedure was the same as in humans. Specific changes preceding or following initiation of cardiopulmonary bypass (CPB), such as inactivation of the coagulation system (400 IU heparin/kg i.v.), haemodilution, and hypothermia (32 degrees C), did not result in any complication. We did not induce cardiac arrest during CPB in order to facilitate haemodynamic stability after weaning from CPB. In three animals a temporary increase in blood pressure occurred after protamine (2.5-3.0 mg/kg i.v.) was given to reverse the heparinization. Within 60 minutes after the end of surgery all animals could be extubated when spontaneous breathing and cough reflex were present. The postoperative follow-up period of nine months was uneventful apart from one animal which developed a superficial wound in the thoracic scar area. We conclude that our technique for ECC is a safe method allowing recovery and long-term follow-up after cardiac surgery in a porcine animal model.