Aortic valve replacement. A randomized study comparing the Björk-Shiley and Lillehei-Kaster disc valves. Transvalvular regurgitation and occurrence of paravalvular fistulas

Comparison of transthoracic and transesophageal color Doppler flow imaging in patients with mechanical prostheses in the mitral valve position

This study determined the relative value of transthoracic and transesophageal color Doppler flow imaging to systolic flow patterns in the left atrium in different types of mechanical prostheses in the mitral valve. Thirty-nine patients were investigated. Based on clinical findings, 36 of 39 patients had normal prosthetic valve function. Seventeen patients were interrogated within a few days after surgery. Systolic regurgitant jets in the left atrium were absent in all patients by both transthoracic pulsed and color Doppler flow imaging. Using transthoracic continuous wave Doppler, however, jets were demonstrated in 8 of 39 patients (21%). Transesophageal color Doppler flow imaging demonstrated systolic regurgitant jets originating from the prosthesis in all patients. Tilting disc valves showed jets during the entire systole (closure and leakage backflow). Each type of prosthesis generated a specific jet pattern. Pathologic regurgitant jets were crescent-shaped, more extensive and turbulent than jets caused by normal closure and leakage backflow. Thus, transthoracic color Doppler flow imaging is not sensitive for detecting regurgitant jets in mechanical prostheses in the mitral valve. All mechanical prostheses show a specific jet pattern, which should be helpful when transesophageal echocardiography is used to identify pathologic backflow.

Seven and one-half years' experience with the Medtronic-Hall valve

The Medtronic-Hall valve was developed to improve on existing tilting disc valves by reducing the risk of valvular thrombosis. This was to be accomplished by improving the hemodynamics and by allowing the disc to move downstream away from the orifice during opening. The valve was also designed for maximal structural durability to minimize the risk of mechanical breakage. With more than 1,000 Medtronic-Hall valves implanted since 1977, the clinical results have been very encouraging. The rates of thromboembolism and thrombosis are low, there have been no mechanical failures and the hemodynamic function, especially with the smaller valves, is excellent.

Regurgitation of prosthetic heart valves: dependence on heart rate and cardiac output

Prosthetic heart valves exhibit closure and leakage backflow; however, no well-controlled study to evaluate the influence of factors such as cardiac output and heart rate on backflow has been reported to date. Four clinically used prosthetic aortic valves (size 27 mm)--St. Jude Medical, Björk-Shiley Spherical Disc, Björk-Shiley Convexo Concave, and Starr-Edwards model 1260--were studied in the aortic chamber of a pulse duplication system at heart rates of 50, 80, 110, and 140 beats/min, cardiac output of 2, 4, 6, and 8 liters/min, and mean aortic pressure of 100 mm Hg. Regurgitation was calculated in percentage and found to vary directly with heart rate and inversely with cardiac output. The range of values obtained were 5.5% for the Starr-Edwards model 1260 valve at 110 beats/min and 8 liters/min, to 37.5% for the Björk-Shiley Convexo Concave valve at 140 beats/min and 2 liters/min. Regurgitation was also calculated in milliliters/stroke and ranged from 3.4 ml/stroke for the Starr-Edwards model 1260 valve at 140 beats/min and 2 liters/min, to 17.3 ml/stroke for the Björk-Shiley spherical disc valve at 50 beats/min and 2 liters/min. Regurgitation associated with prosthetic heart valves may present a problem clinically, particularly under conditions of low cardiac output and tachycardia.

Aortic valve replacement. A randomized study comparing the Björk-Shiley and Lillehei-Kaster disc valves. Long-term results

Three hundred patients were selected at random in order to compare the Björk-Shiley (B-S) and Lillehei-Kaster (L-K) valves in the aortic position. The mean follow-up time was 4 3/4 years (range 3 1/4-7 years). There were 15 late deaths in the B-S group and 23 in the L-K group. The incidence of sudden and unexpected deaths was much higher in the L-K than in the B-S group (10:1). The 7-year actuarial survival rate was 82% in the B-S and 76% in the L-K group. In both groups the survival rate was higher in patients with large valves than in those with small valves; in the L-K group this difference was significant (p less than 0.02). The overall thrombo-embolic rate was 3.2 per 100 patient years in the B-S and 2.8 in the L-K group. Valve thrombosis occurred in 3 patients with B-S valves and in 4 with L-K vales. One of the L-K valves was thrombosed early after operation due to faulty suture technique. Of the long-term survivors of working age 80% in the B-S and 70% in the L-K group returned to work. There was a close correlation between functional capacity (NYHA) and the employment rate.