Echocardiographic and phonocardiographic characteristics of the Hall-Kaster aortic disc valve prosthesis.

The Hall-Kaster (H-K) valve is a new tilting disc valve prosthesis which has recently been taken in use of heart valve replacement. Simultaneous echo- and phonocardiographic studies were performed in nine patients with a normally functioning H-K prosthesis in the aortic position. The prosthesis is well recorded by a M-mode echocardiogram. The opening and closing of the disc were easily recorded in all cases. The disc itself opened and closed very rapidly, in most cases too rapidly for quantitative assessment. In two cases, mean opening and closing velocity was measured to 38.8 cm/s and 51.8 cm/s, respectively. The opening sound of the prosthesis was rarely identified on the phonocardiogram. The closure of the valve was recorded as a discrete single high frequency sound. Systolic time intervals measured by combined echo- and phonocardiography revealed values for pre-ejection period similar to the predicted values, while the left ventricular ejection time tended to be slightly shorter than expected.