Ann Thorac Surg 1995;59:1404
© 1995 The Society of Thoracic Surgeons
INVITED COMMENTARY
Mark F. O'Brien, FRACS
Department of Cardiac Surgery, The Prince Charles Hospital, Rode Rd, Chermside, Brisbane 4032, Australia
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Introduction
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 Introduction
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See also page 1397.
For decades (1962 to 1995), the pioneers and many other workers with allograft valves have extolled their virtues, but few surgeons have used them on a regular basis for any sustained period. Why? Intrinsic valve failure and the technical difficulties of implantation producing incompetence have necessitated reoperation.
A ``perfectly'' competent allograft valve has been difficult to produce. Sufficient reasons therefore have been present to turn many surgeons away. Patients and cardiologists do not like to see or hear about the aortic regurgitation on echocardiography! But the ``modern-day'' allograft is (1) implanted within 1 to 2 days after collection, (2) cryopreserved within 24 hours of collection, and (3) inserted as a root replacement instead of by subcoronary implantation. This type of allograft has revolutioned the immediate clinical and probably the long-term results of allograft aortic valve replacement. Nevertheless the non-immunosuppressed aortic valve will inevitably and eventually fail. But, for most patients, the active lifestyle for that one to three decades after the initial implantation will have been the result of excellent hemodynamics, a minimal risk of early and late infection, and no anticoagulant therapy with negligible risk of thromboembolism.
Addressing the specific issue of technical implantation, the subcoronary so-called scalloped allograft valve is difficult to implant into the aortic annulus with consistently acceptable results. The congenital bicuspid valve that is present in a majority of those young and middle-aged patients most deserving of an allograft and the destroyed infected root both present distorted aortic roots. This asymmetry increases the risk of malalignment of the allograft. Using the technique of a total free root replacement with pedicle coronary artery implantation virtually solves this problem. Of the last 100 allografts implanted at The Prince Charles Hospital, 89% have been root replacements, and of the last 200 allografts, 76% have been root replacements. The former technique of subcoronary implantation is now in 1995 rarely used at our institution. Perhaps its only indications may be in the small annulus of less than 21 mm where a satisfactory competent implant may be obtained. Jones and associates from Emory University are to be congratulated on their clinical experience and on this analysis focusing on an important topic, which is being shown by several reports to be giving improved allograft results. Perhaps more patients will benefit from the advantages of allograft implantation if surgeons, already familiar with root replacement with other devices, are prepared to go through the shorter learning curve of using these tissue valves with root replacement techniques. In recent years implantation of both aortic allografts and pulmonary autografts has refocused on a more widespread use of the root replacement.
