Central Haemodynamics at Rest and During Exercise Before and After Aortic Valve Replacement with the Björk-Shiley Tilting Disc Valvel in Patients with Isolated Aortic Stenosis

A pre- and postoperative haemodynamic study at rest and during exercise was performed in 37/53 consecutive patients with isolated aortic stenosis operated upon with the Björk-Shiley tilting disc valve. After operation there was a significant average decrease in heart volume in supine position and a significant increase in working capacity. Total haemoglobin decreased slightly, but blood volume remained unchanged as did the kinetics of circulation at rest and during exercise. Left and right ventricular pump function, as judged from systolic and end-diastolic pressures, mean atrial pressures and left ventricular systolic and diastolic work, was improved following operation. Marked reductions were found in left ventricular systolic pressures at rest and during exercise. Left ventricular end-diastolic, pulmonary artery and right heart pressures decreased significantly. Pulmonary vascular resistance remained unchanged. After operation the systolic aortic pressure and pulse pressure increased significantly during exercise. There were no late thrombo-embolic episodes in the 48 survivors. The clinical improvement, with marked decrease of angina and absence of syncope, is related to the unloading of the left ventricle following aortic valve replacement with the Björk-Shiley valve.