Transcatheter placement of aortic valves is a therapeutic option currently under investigation. This study evaluates the placement of an aortic valve in the supra-coronary position in pigs with severe aortic insufficiency.
Fifteen pigs were randomized to 3 equal groups: supra-coronary aortic valve (experimental) vs. control vs. off pump control. The off pump control group was not placed on cardiopulmonary bypass (CPB) and was used to control for the possible effect of CPB. Median sternotomy with isolation of the right coronary artery was performed in all 3 groups. The experimental and control groups were placed on CPB and the aorta was cross clamped and transected. In the experimental group, all leaflets of the aortic valve were excised, and a mechanical valve was placed in the supra-coronary position. In both groups the aorta was re-anastomosed and the animals were weaned from CPB. All surviving animals were monitored for 4 hours and administered escalating doses of dobutamine while hemodynamic, laboratory, and coronary flow data were recorded.
All 5 animals in the experimental group died upon discontinuation of CPB. All animals were age and weight matched. All pre-operative and pre-CPB hemodynamic, laboratory values, and coronary flow characteristics were not significantly different among the 3 groups. None of the hemodynamic values or coronary flow characteristics were significantly different between the control and the off pump control groups throughout the 4 hour monitoring period. The significant differences during the 4 hour monitoring period in laboratory values between the control and off pump control groups include creatine kinase (CK), CK-MB fraction, troponin-I, and aspartate aminotransferase (AST); all p values <0.05.
Aortic valve replacement in the supra-coronary position is fatal in pigs with severe aortic insufficiency. Based on the hemodynamic and coronary flow data, CPB does not appear to be a factor in this conclusion.
Advances in aortic valve replacement are being continually investigated. This data suggests supra-coronary placement of an aortic valve is not a feasible alternative in severe aortic insufficiency.
M. Michel, None.