Replacement of the aortic valve or the full aortic root can be performed using a variety of stentless valve devices. The three main options are a porcine aortic root-valve conduit (Medtronic Freestyle, Medtronic Inc., Minneapolis, MN), and the “human” valve options of the aortic homograft and the pulmonary autograft (Ross Procedure). Having reviewed the subject almost 30 years ago,1 it is interesting to note how some things have changed but much has remained the same. Table 29-1 summarizes advantages and disadvantages of current replacement options.
TABLE 29-1:Comparison of Mechanical and Tissue Alternatives for Aortic Valve Replacement |Favorite Table|Download (.pdf) TABLE 29-1: Comparison of Mechanical and Tissue Alternatives for Aortic Valve Replacement
| ||Mechanical ||Stented bioprosthetic ||Stentless bioprosthetic ||Allograft ||Autograft |
|Advantages || |
Larger EOAI compared with stented valve.
Root replacement is available option
All biologic material good for use in endocarditis
Long durability possible
|Disadvantages || |
Poor EOAI in small valve sizes
More complex operative technique
Double valve or Root replacement with potential late failure of either
The first choice for aortic valve replacement (AVR) was the homograft aortic valve. Gordon Murray created an animal model to implant an aortic homograft valve in the descending aorta2 and was the first to apply the concept in the human demonstrating function for up to 4 years.3
Duran and Gunning at Oxford described a method for orthotopic (subcoronary) implantation of an aortic homograft valve in 19624 and in 1962 both Donald Ross in London,5 and Sir Brian Barratt-Boyes in Auckland,6 did this successfully in humans.
Initially, homograft aortic valves were implanted shortly after collection.7 This impractical method was rapidly supplanted by techniques to sterilize and preserve the valve for later use. Early methods employed beta-propiolactone6,8 or 0.02% chlorhexidine,9 followed by ethylene oxide or radiation exposure.10 Some were preserved by freeze-drying.6,10 Recognizing that the incidence of valve rupture was high in chemically treated valves, Barratt-Boyes introduced antibiotic sterilization of homografts in 1968.11 Cryopreservation of allografts was introduced in 1975 by O’Brien and continues to be the predominant method.12,13 Experimental use of autologous valve transplantation began in 1961 when Lower and colleagues at Stanford transposed the autologous pulmonic valve to the mitral position in dogs14 and shortly thereafter to the aortic position.13 Donald Ross applied this to humans, reporting in 1967 clinical experience replacing either the aortic or the mitral valve with a pulmonary autograft.14 Nearly 20 years later the autograft was finally done in America by Elkins and Stelzer.15 The operation came to be known as the ...