Central Haemodynamics at Rest and During Exercise Before and After Operation with the Björk-Shiley Tilting Disc Valve in Patients with Aortic Incompetence

Abstract

Twenty-two out of 46 consecutive patients with aortic incompetence, who were operated upon with the Björk-Shiley disc valve during the period January 1969 to November 1971, were subjected to clinical and haemo-dynamic pre- and postoperative studies. Before surgery, this material was characterized by high mean age, preponderance of male patients, high incidence of arrhythmias and low functional capacity. Regurgitation at aortography was grade IV and the pressure differences across the aortic valve were negligible. Heart volumes were grossly enlarged, working capacity low, and pump function (as represented by effective stroke volume, kinetics of circulation, and filling pressure of the left ventricle) was markedly impaired. Congestive heart failure and pulmonary hypertension were common features in this group of patients, who were incapacitated at an advanced stage of the disease.

The main effect of aortic valve replacement was a shift of the central circulation to a more normokinetic type, an increase in effective stroke bolume and a decrease of the left ventricular filling pressure. The large pre-operative blood volumes were normalized. Working capacity increased significantly and cardiac enlargement was reduced. Marked postoperative reductions in left atrial mean, pulmonary artery and right heart pressures, both at rest and during exercise, were observed and central aortic pressure was normalized. Clinical improvement was obtained in 19/22 patients (86%).

Aortic valve replacement involved a hospital mortality of 2% (1/46 patients), while 5 patients (11 Yo) died later during the 9-month follow-up period. No thrombo-embolic complications occurred during the same period. The in ciuo rheology of the Bjork-Shiley prosthesis, even in its smaller sizes, was reported to be highly satisfactory. Aortic valve replacement with this prosthesis in aortic incompetence may therefore be regarded as eliminating the volume load of the left ventricle without adding a pressure load.