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Even though there has been some criticism regarding the Doppler evaluation in prosthetic valves because of inter-observer and intra-observer variability, among other factors, and Doppler study has a tendency to have falsely high gradients compared to invasive studies, especially mechanical aortic prostheses, Doppler evaluation can provide reliable hemodynamic information about valve function. This test may be particularly useful if used serially, when baseline values are known. Doppler measurement of gradient and valve area has an expected normal range that is specific for the prosthetic type, size, anatomical position, and chronological age. Clearly, a database involving these aspects is needed to provide a more accurate normal range. This study is intended to provide guidance for echocardiographers.

In this 3 year study of 209 patients who underwent mitral valve replacement with the newer Beall prostheses (Models 104 and 105) the operative mortality rate was 5.2 per cent. None of these deaths was related to the valve. This prosthesis features a larger frustrum area and a "turtle-neck" sewing ring which permits its rapid insertion with a continuous suture technique. Of the 20 (9.5 per cent) late deaths, two were due to thrombosis of the valve. Among the 178 survivors, 17 developed thromboembolic complications; however, 10 of these patients recovered. Late clinical results have been quite satisfactory in over 90 per cent of the survivors. In the 15 patients who underwent hemodynamic studies postoperatively, the cardiac index and pulmonary artery pressure showed significant improvement; however, they still had transvalvular gradients at rest. The improvement in the design of this prosthesis has been an important factor in lowering the operative risk and improving the late results of mitral valve replacement.

Over 13 years, 96 Beall prostheses (80 Teflon, 16 Pyrolite) explanted at surgery were examined for durability, material wear, and clinical symptoms leading to surgical indication for excision were evaluated. The Teflon valves showed progressive disc wear and notching and two cases of disc escape from the cage; the Pyrolite discs were intact in all prostheses. The Dacron-Velour covering common to both types showed dehiscence at the inlet, significantly more severe after the third implant year in the Teflon (p less than 0.005) than in the Pyrolite prostheses. Sixty-nine (85 percent) cases with Teflon valves showed clinical manifestations of congestive heart failure due to prosthetic dysfunction; in 50 there was significant hemolytic anemia. Seven (44 percent) of the 16 Pyrolite disc valves were excised primarily because of dysfunction. The degree of hemolysis with the Pyrolite valves was usually mild. These data clearly suggested the advisability of early excision of the Beall Teflon prostheses in symptomatic patients and a close follow-up in patients with the Pyrolite models.

Seven cases of massive thrombosis of an aortic Bjork-Shiley prosthesis were encountered among 433 valvular implants. Four patients died before treatment could be instituted, and three underwent repeat surgery successfully. Anticoagulation therapy was probably well maintained in four, and poorly maintained in three patients. These cases illustrated the need for a high index of suspicion and prompt recognition of this complication in patients with Bjork-Shiley prostheses. The diagnosis of massive thrombosis should be suspected with the rapid onset of (1) signs of congestive heart failure, (2) absence or attenuation of valvular clicks, (3) aortic regurgitation, or (4) hemolytic anemia. Salvage of these patients requires emergency replacement of the thrombosed prosthesis or removal of the thrombus.

Detailed pathological studies are reported on 20 cloth-covered Beall mitral valve prostheses, which had to be removed for valve failure nine months to 10 years after implantation. Results in all patients except one indicated that there was a progressive and persistent granulomatous reaction that continued up to at least 10 years. Although the rate of tissue ingrowth into the valve decreased with time, the total volume of tissue formation increased. Cloth wear and disruption and deformity of the teflon discs was frequently seen. In these 20 valves the desired result--namely, the complete and smooth endothelialisation of the prosthesis--was certainly not achieved.