Anesthetic and Postoperative Protocols for a Canine Model of Reversible Left Ventricular Volume Overload

The purpose of this study was to develop anesthetic and postoperative methods that could be used in a canine model of reversible left ventricular volume overload (LVVO). LVVO was created by inducing mitral regurgitation (MR) in adult conditioned dogs. Using fluoroscopy, MR was induced by passing urologic grasping forceps into the left ventricle through a carotid artery and rupturing one or more chordae tendinea. Cardiac catheterization was performed after significant cardiac dysfunction developed (3 months after creation of MR) in order to collect data to confirm reduced contractile function. The MR was repaired by replacing the damaged valve with a bovine pericardial xenograft. Dogs were followed with sequential cardiac catheterizations to determine if the valvular replacement reversed the cardiac dysfunction. To develop this model, unique anesthetic and post-operative care protocols had to be instituted. In order not to exacerbate the existing cardiac dysfunction, a high dose narcotic anesthetic regimen using a sufentanil infusion at 9-13 microgram/kg h-1 was developed in association with cardiopulmonary bypass and hypothermia for the mitral valve replacement surgery. Intensive postoperative care protocols that involved major personnel and pharmaceutic interventions were necessary. Using our methods 11/17 dogs survived the procedure and were included in the protocol for study of mechanisms involved in reversal of cardiac dysfunction.