A Simple Method for Cardiac Surgery in Rats

A recovery model of minimally invasive cardiopulmonary bypass in the rat

This study was undertaken to develop a rodent (rat) model of cardiopulmonary bypass (CPB) that has been designed to mimic functionally the minimally invasive clinical setting. The circuit is similar to the clinical model in terms of its construction, configuration, material surface area to blood volume ratio, and priming volume to blood ratio. The overall priming volume was 10 mL. Thirty-six male Sprague-Dawley rats (422 +/- 32 g) were anaesthetized while maintaining spontaneous ventilation. Anticoagulation was achieved with heparin (500 IU/kg). Blood arterial pressure was monitored continuously. Normal central temperature was maintained throughout. Intermittent arterial blood gas levels also were monitored. All animals were cannulated in preparation for CPB; however, CPB, utilizing a double roller pump and a flow rate of 100 mL/kg/minute for 60 min, was initiated in only 18 animals, the remaining 18 animals acting as non-CPB controls (Sham). The animals were haemodynamically stable. After the operative procedure, the animals were allowed to recover from the anaesthesia and, after transfer to a recovery facility, were monitored for a period of 1 week. There were no differences between the groups in terms of blood gas analysis and blood pressure data; all animals survived the procedure and had an uneventful follow-up. Differences were found between the CPB animals and the Sham group in terms of TNFalpha used as a marker of inflammatory processes. This trend tends to support this model as an analogue for the clinical scenario for future studies of CPB-related inflammation. Overall, the CPB procedure was easy to perform and was associated with excellent survival. This recovery model is an effective tool to perform pathophysiological studies associated with minimally invasive CPB.

A recovery model of partial cardiopulmonary bypass in the rat

This study was undertaken to develop a recovery model of cardiopulmonary bypass (CPB) in rats. Twenty male Wistar rats (475-550 g) were anaesthetized, mechanically ventilated and the femoral vessels cannulated. The extracorporeal circulation circuit comprised a roller pump, a venous reservoir and a modified Capiox 308 paediatric membrane oxygenator. Priming consisted of 20 ml of fresh homologous blood and 15 ml of colloid. Anticoagulation was achieved with heparin (500 IU/kg). Blood gas analysis, blood pressure monitoring and survival studies were performed in CPB (n=10) and Sham (n=10) rats. Partial CPB was always easily established and was conducted at a flow rate of 100 ml/kg/min for 90 min Blood gas analysis and blood pressure data did not differ between the two groups. All CPB rats survived and the 3-week follow-up period remained uneventful. The rat model of CPB was easy to perform and was associated with excellent survival. This recovery model should allow us to study the pathophysiological processes underlying post-CPB multiple organ dysfunction.