The next step in the operation involves attaching the three commissures to the prosthesis. This surgical step is extremely important, and the commissures should therefore be anchored anatomically correctly to the prosthesis. Once the commissures have been attached to the prosthesis with the previously stitched Prolene retention sutures, hemostatic suturing onto the prosthesis of the rest of the aortic border of the aortic root is carried out using 4–0 Prolene. This is best done with a 4–0 Prolene suture with a small needle (V7). The seal on the valve is then checked using saline.
In the next surgical step, first the left coronary ostium and then the right coronary ostium are reimplanted onto the prosthesis using the usual technique. In the final step of the operation, attachment of the distal row of sutures on the prosthesis to the distal ascending aorta is completed. After opening the aortic clamp, intraoperative TEE checking must be carried out in all cases to test the results of the aortic valve reconstruction.
Yacoub operation
The principle of reconstruction of the aortic valve and aortic root, as well as replacement of the ascending aorta, in the Yacoub operation also involves resection of the entire aortic root. The Dacron prosthesis is then trimmed in such a way that three new aortic sinuses are cut out of the prosthesis. After dissection of the aortic root, these neosinuses are then sutured directly onto the aortic valve annulus or residual aortic sinus using a continuous suture.
The modified Yacoub operation is a special form of the technique in which only the noncoronary aortic sinus is replaced with a tongue of the Dacron prosthesis. This is often possible when only the noncoronary aortic sinus shows aneurysmal dilation, while the right and left coronary sinuses have a normal caliber. It is then possible to carry out a supracoronary replacement of the ascending aorta in combination with complete replacement of the noncoronary aortic sinus.
Replacement of the ascending aorta, aortic root, and aortic valve
Mechanical valve conduit
In patients with significant structural aortic valve disease and/or dilation of the aortic annulus, or with aneurysm of the aortic root and ascending aorta, implantation of a valve-bearing conduit may be considered. The fundamental technique nowadays consists of excising the coronary ostia and using an end-to-end technique to reimplant them into the prosthesis (the button technique). After resection of the ascending aorta, dissection of the right and left coronary ostia, and excision of the aortic valve, implantation of the aortic conduit starts with the stitching of the valve sutures using an eversion technique with felt blocks. The sutures must be stitched very close together and distributed evenly along the ring. A sufficiently large valve can be implanted in almost all cases, and one should therefore make sure that not too large a conduit is used, as otherwise too much tension on the annulus is produced, and the sutures are then tied. After this, the coronary ostia are reimplanted—first the left ostium and then the right one. Depending on the quality of the wall, small felt rings can be used to support the 5–0 Prolene suture. One of the most important steps in this operation is correct localization of the site for the ostium anastomosis. It is sometimes advantageous to hold back the heart slightly to prevent later buckling of the coronary arteries. The final step in the operation is the distal aortic anastomosis, which is again created over a previously anastomosed felt strip with 3–0 Prolene.
Overall, this surgical technique can be carried out with excellent results. The Cabrol method (Cabrol et al. 1980) is hardly used any more, as direct reimplantation of the coronary ostia is in principle always possible and is associated with much better results than the Cabrol method. The same also applies to the original Bentall method.
Biological valve conduit (xenograft)
Biological valve conduits are now available (e.g., the Medtronic Freestyle®). In this method, swine aortic valve, aortic root, and proximal ascending aorta are used. In principle, the surgical method is comparable with the mechanical valve conduit, but the following points need to be taken into account:
Allograft implantation
Implantation (actually transplantation) of fresh or cryoconserved heart valves and aortas (allografts) can also be used (like biological conduits) for aortic root replacement. One of the major limitations in using allografts is that they are difficult to obtain, however. In addition, the quality of biological valve conduits has improved markedly in recent years, so that allografts are now hardly ever used for aortic root replacement. There may be possible indications for allograft implantation in patients with endocarditis or in young patients. Data for the long-term results vary widely from center to center and depending on the surgical method used (the free-standing root or inclusion techniques). In contrast to aortic allografts, pulmonary allografts in the aortic position are unfavorable and should not be implanted.
Pulmonary autograft (Ross operation)
The principle of the Ross operation involves transferring an endogenous (autologous) pulmonary valve to the aortic position and using an allograft to replace the pulmonary valve. This surgical technique is based on the desire to replace the aortic valve with an endogenous valve (pulmonary valve). The hope is that this “biological” valve will be much more durable than all the other types of biological heart valve, particularly in younger patients. The disadvantage of the method is that it corrects a univalvular condition using a bivalvular heart-valve replacement. Despite this, the long-term results (see below) are excellent, and the rate of repeat surgery on the new aortic valve is extremely low. If repeat surgery is necessary, it is almost always the pulmonary graft that is needed (for details, see the Results section below). With the introduction of valvular prostheses that can be implanted transfemorally or transapically, this type of second valvular replacement will be associated with even lower risk in the future.
Special techniques for ascending aorta replacement in acute Stanford type A dissection
In acute type A dissections, numerous modifications are available in comparison with operations for degenerative aneurysms. These are based on the fact that the dissected aortic wall is extremely fragile in acute type A dissection, and in addition the aim must be to resect