Aortic valve replacement with the Björk-Shiley tilting disc valve prosthesis. Clinical experiences in 50 cases

Effect of aortic valve replacement on the left ventricle. A ciné-angiographic evaluation

Heart catheterization and quantitative left ventricular ciné-angiography data on thirty patients with aortic vlave disease were analyzed pre-operatively and 12 months after insertion of a Björk-Shiley tilting disc valve. The pre-operative and postoperative data were compared and also with a control group of 22 patients with no organic heart disease. According to the functional NYHA classification, 14 patients had improved, 14 were unchanged and 2 had deteriorated. Regurgitation had been totally corrected in 27 patients, and the high or moderate pressure gradient between the left ventricle and aorta had been reduced, but the valve itself caused a gradient of 5 to 35 mmHg. The pre-operatively abnormal pump function, hypertrophy, dilatation and impaired myocardial function had all become markedly more normal. The most obvious changes were an improvement in stroke work relative to end-diastolic volume and myocardial mass (p less than 0.001) and reductions in end-diastolic volume (p less than 0.001), pump power (p less than 0.001) and myocardial mass (p less than 0.001). Aortic valve replacement seems to be an appropriate procedure in cases where the left ventricular performance and haemodynamics are sufficiently disturbed.

Intraoperative changes in coronary resistance during aortic valve replacement

Coronary vascular resistance was investigated in 10 patients undergoing aortic valve replacement using continuous constant-pressure coronary perfusion at 32 degrees C. After coronary flow was initiated, resistance was low but increased steadily until it reached a certain resting level. The plateau was attained faster after a short period of anoxia than after a longer period. The initial postischemic resistance was dependent on the duration preceding anoxia, being of the same magnitude after short and moderate periods of anoxia but significantly higher after a long period. This resistance difference between the groups lasted for the whole perfusion. The total coronary resistance and flow reached a plateau in 30 minutes, while resistance increased threefold but flow decreased to half of the initial postanoxia flow. Our results indicate the importance of initiating coronary perfusion soon after aortic cross-clamping to avoid increase in the initial vascular resistance and subsequent inadequate myocardial flow.