Transapical off-pump removal of the native aortic valve: a proof-of-concept animal study.

OBJECTIVE

This study evaluates the feasibility of off-pump native aortic valve removal in preparation for transapical aortic valve replacement. Off-pump aortic valve replacement is performed by balloon predilatation of the native valve followed by insertion of a stented prosthesis. In patients with calcified annuli and cusps, particulate embolization, suboptimal prosthesis sizing, and perivalvular leaks may occur. Therefore, native valve removal may improve outcomes after transapical aortic valve replacement.

METHODS

The aortic cusps were sequentially removed from 10 pigs in an off-pump procedure. A temporary valve was inserted percutaneously into the ascending aorta to prevent aortic regurgitation. The electrocardiogram, coronary blood flow, and arterial, left atrial, and ventricular pressures were continuously monitored.

RESULTS

Removal of the aortic cusps caused a drop in diastolic arterial pressure and its equalization with left ventricular diastolic pressure. Systolic pressure decreased by 13.5%. Left atrial pressure increased by 86.0%. Coronary blood flow decreased by 39.9% and its pattern changed from mostly diastolic to mostly systolic. Electrocardiographic signs of ischemia appeared almost immediately. Percutaneous insertion of a temporary valve in the ascending aorta increased diastolic pressure and caused a tendency toward echocardiographic normalization.

CONCLUSIONS

Aortic valve removal in a healthy beating heart causes acute massive aortic regurgitation, hemodynamic instability, and the rapid onset of myocardial ischemia. Reduction of left ventricular volume overload, by placement of a temporary valve in the ascending aorta, mitigates myocardial distress, helps stabilize hemodynamic parameters, and may be a useful tool to allow surgical manipulations of the aortic valve and annulus during transapical aortic valve replacement procedures.