Aortic valve surgery: Clinical studies after autograft, homograft and prosthetic valve replacement

Abstract

Aortic Valve Surgery Clinical studies after autograft, homograft and prosthetic valve replacement Obaid Aljassim, MD Department of Cardiovascular Surgery and Anaesthesia, Sahlgrenska University Hospital and University of Gothenburg Introduction and Aims: Aortic valve disease in symptomatic adult patients often requires surgery. Several alternatives are available: repair, mechanical and biological prostheses, homograft and the Ross procedure. In the process of choosing valve substitute, the individual patient’s characteristics are matched against the characteristics of the different valve alternatives. This thesis includes clinical studies addressing outcome after the Ross procedure, after homograft replacement in endocarditis and Doppler versus catheter findings in patients with prosthetic valves. Methods: In Study I, surgical correction of autograft mismatch in the Ross operation (n=77) was investigated. In Study II we established the normal aortic dimensions using echocardiography in normal controls (n=38) and compared these findings with Ross operated patients (n=71) in a long-term follow up (101±31 mo). In Study III, patients with prosthetic (n=31) or native valve endocarditis with abscess (n=31) were operated with a homograft replacement, and followed for 37±11 months. In Study IV we investigated the flow resistance of mechanical and biological aortic valves using simultaneous Doppler and left ventricular and aortic pressure measurements (high-fidelity catheters). Results: Study I: Among the 24 patients without surgical correction an early moderate aortic regurgitation was present in eight patients (33%) compared with two of the following surgically corrected 53 patients (4%, p=0.001). Study II: A large proportion of the patients showed dilatation of the autograft (43%) and native aorta (32%) at late follow-up, and 5 were re-operated due to dilatation. There was a progression in both autograft and native aortic dimensions from the baseline to the follow-up. Only baseline autograft size did predict late dilatation (>4 cm). Study III: Nine patients (15%) died within 30 days. Variables associated with early mortality were higher Cleveland Clinic Risk Score (p=0.014), ECC-time (p=0.003), inotropic support (p=0.03), bleeding (p=0.01) and myocardial infarction (p<0.001). Cumulative survival was 82%, 78%, 75% and 67% at one, three, five and ten years, respectively. Quality of life (SF36) was not significantly different to a matched healthy control group. Study IV: There was a strong linear relation between catheter and Doppler gradients (r = 0.85 to 0.92). Doppler overestimated catheter gradients in both the mechanical and stented biological valve. Conclusions: Aortic regurgitation immediately after the Ross procedure can be minimized with surgical correction of anatomical mismatch in the aortic root. The autograft as well as the native aorta continues to dilate and this may lead to reoperation. Severe acute aortic endocarditis treated with homograft replacement is still associated with a substantial early complication rate and mortality. Long-term survival, quality of life and homograft function is satisfactory in patients surviving the immediate postoperative period. In the first in vivo study of the relation between Doppler and catheter gradients in prosthetic valves, we found a significant Doppler-catheter discrepancy in bioprostheses. Doppler overestimates the net gradients in both mechanical and biological prostheses.