AVR Group Research Articles

Early surgical results of the Medtronic-Hall valve.

A clinical trial with the Medtronic-Hall (M-H) valve was started in November 1981. From then until December 1982, 157 patients underwent heart valve replacement: Mitral valve replacement (MVR) 63 patients, isolated aortic valve replacement (MVR) 41 patients, and 53 underwent combined mitral-aortic valve replacement (MVR + AVR). Hospital mortality was 2.5% overall (4/157). The total follow-up was 147 patient-years (range 1 to 12 months). Late mortality was 3.2% for MVR, 2.5% for AVR and 1.9% for double MVR + AVR. Oral anticoagulation therapy (Dicumarol) was administered to all patients included in this study. There were no anticoagulant complications and no prosthetic bacterial endocarditis registered in this series of patients up to date. The incidence of systemic embolism was 2.5 events per 100 patient-years in the AVR group. No embolic episodes have been registered in the other 2 groups. The incidence of valvular dysfunction (expressed as events per 100 patient-years) were: --Perivalvular leak (0 MVR, 0 AVR and 2 MVR + AVR) --Valve thrombosis (1.7 MVR, 0 AVR and 0 MVR + AVR) --Mechanical dysfunction (1.7 MVR, 0 AVR and 0 MVR + AVR) Despite a short follow-up, the results with the Medtronic-Hall valve are encouraging and compare favorably with other mechanical prostheses.

Long-term experience with porcine aortic valve xenografts

Between 1971 and 1975, glutaraldehyde-preserved porcine aortic valve xenografts were employed for isolated replacement of the mitral valve (MVR) in 243 patients, replacement of the aortic valve (AVR) in 167 patients, and double valve replacement (AVR and MVR) in 51 patients. Postoperatively, long-term anticoagulation was not routinely given. Operative mortality rates for AVR, MVR, and double valve groups were 7.8, 6.0, and 11.8 per cent, respectively; the majority of early postoperative deaths were associated with concomitant coronary artery disease. No death was attributable to xenograft dysfunction. Follow-up of all patients was obtained. The total duration of follow-up for the MVR group was 347 patient-years, for the AVR GROUP 148 148 patient-years, and for double valve replacement 37 patient-years; maximum follow-up for these three groups was 4.4, 4.0, and 2.4 years, respectively. Actuarial analysis of postoperative survival rates at a common interval of 3 years showed 78 per cent for MVR patients, 91 per cent for AVR patients, and 80 per cent (projected) for patients with double valve replacement (85, 96, and 91 per cent for operative survivors, respectively. At this same interval 92 per cent of MVR patients, 99 per cent of AVR patients, and 93 per cent (projected) of patients with double valve replacement were free of thromboembolic episodes. Altogether, 12 of the total 512 valves implanted exhibited some evidence of dysfunction during the entire period of follow-up evaluation, but in only 2 instances (both mitral) was intrinsic pathological involvement of the xenograft tissue documented. Actuarial analysis of xenograft dysfunction at a common interval of 3 years after operation showed 95 per cent of MVR patients, 98 per cent of AVR patients, and 97 per cent (projected) of patients with double valve replacement to be free of this complication. These data support the use of glutaraldehyde-preserved porcine xenografts as superior bioprostheses that pose a low risk of thromboembolism without anticoagulation. The over-all durability of such valves, within the restriction of a maximum current follow-up interval of 4.4 years, appears comparable to that of currently available mechanical prostheses and justifies continued clinical use.