MITRAL-VALVE REPLACEMENT VIA A RIGHT MINI-THORACOTOMY IN THE DOG - USE OF CARBON-DIOXIDE TO REDUCE INTRACARDIAC AIR

Objective: To develop a clinically applicable method of minimally inva sive mitral valve replacement (MVR) with cardioplegia, and examine the ability of carbon dioxide (CO2) to improve de-airing. Methods: MVR wa s performed via a 5 x 3-cm right lateral minithoracotomy in eight grey hounds. Peripheral cardiopulmonary bypass and an ascending aortic ball oon catheter (endoaortic clamp) were used for cardioplegia and aortic root venting. The endoaortic clamp was inflated in the ascending aorta under fluoroscopy and cardioplegic solution was infused. In four dogs , CO2 at 2 l/min was used to displace air in the chest. A left atrioto my was made, the valve exposed and a mechanical valve implanted. After left atrial closure, retained intracardiac gas was aspirated from the aortic root and corrected in a bubble-trap. The endoclamp was deflate d and the animal weaned from bypass. Results: A satisfactory MVR was p erformed in all cases. The clamp time was 64 +/- 13 min and all dogs w ere stable post-bypass. In the CO2 group, intrathoracic CO2 was mainta ined above 86% and 0.1 +/- 0.1 mi of gas was collected, compared to 1. 3 +/- 0.8 ml in the non-CO2 group (P<0.05). Conclusions: Femoro-femora l bypass and use of the endoaortic clamp allow a safe and efficacious MVR via a right minithoracotomy in the dog. A. high intrathoracic CO2 concentration reduces the amount of retained intracardiac gas. (C) 199 7 Elsevier Science B.V.