Intermittent aortic regurgitation following aortic valve replacement with the Hall-Kaster prosthesis.

Intermittent aortic regurgitation (AR) was encountered in four of 160 consecutive patients subjected to aortic valve replacement (AVR) with the Hall-Kaster prosthesis. In all four cases, mechanical obstruction to the free movement of the occluder was carefully excluded. All cases were confirmed at reexploration of the valve. The major orifice of the valve was reorientated with correction of AR. A possible mechanism for this phenomenon is wide opening of the occluder beyond the axis of blood flow, resulting in nonclosure during diastole. Meticulous care should be taken in the orientation of this aortic prosthesis to avoid its opening beyond the axis of flow and resulting in postbypass AR.