Haemodynamic Results of Aortic Valve Replacement with the Kay-Shiley Disc Valve

Abstract

Thirty-nine patients, operated on 8 to 14 months previously with replacement of the aortic valve by a disc valve (Kay-Shiley), were subjected to a postoperative follow-up investigation including right and left heart catheterization. Pre-operatively, aortic stenosis was present in 14 cases, aortic insufficiency in 8, combined stenosis and insufficiency in 15 and an associated mitral stenosis in 2 cases.

Physical working capacity (W₁₅₀) was unchanged, while exercise tolerance (W_max) was significantly increased after operation (from 460 to 670 kpm/min). Cardiac output in relation to oxygen uptake was lower than normal pre-operatively and was unchanged postoperatively. Left ventricular pressures diminished significantly; the peak systolic pressure decreased from 210 to 157 mmHg at rest and from 241 to 172 mmHg during exercise, and the end-diastolic pressure from 23 to 13 mmHg at rest and from 32 to 19 mmHg during exercise. Left atrial (or PCV) mean pressure decreased from 17 to 10 mmHg at rest and from 31 to 16 mmHg during exercise.

Systolic pressure differences across the prosthesis were observed in all patients. The peak pressure difference at rest was in average 28 mmHg and increased to 37 mmHg during exercise. The mean pressure difference averaged 24 mmHg at rest and 31 mmHg during exercise.

The calculated orifice area of the prosthesis, according to the Gorlin formula, averaged 1.36 (±0.3) cm² at rest and 1.54 (± 0.4) cm² during exercise, and was in average 64% of the actual orifice area.

The improvement of cardiac function observed postoperatively is explained by a reduction of cardiac work in combination with a higher distensibility of the left ventricle, leading to decreased pressures in the left atrium and pulmonary circulation.