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J Thorac Cardiovasc Surg 2001;121:818-819
© 2001 The American Association for Thoracic Surgery
Letters to the Editor |
Clinic for Cardiovascular Surgery, University Hospital of Geneva, 24, rue Micheli-du-Crest, 1211 Geneva 14, Switzerland
To the Editor:
I enjoyed reading Westaby's comments regarding my article concerning aortic valve replacement with the Freestyle stentless bioprosthesis (Medtronic, Inc, Minneapolis, Minn), published in the June 2000 issue of this Journal.
1
Westaby raises a number of criticisms that I would like to answer. First, in my article, I never stated that patients with substantial discrepancy between the anulus and sinotubular junction diameters were not considered for implantation of the Freestyle valve. On the contrary, we demonstrated that the technique described in the article is able to correct even great discrepancies between the aortic anulus and sinotubular junction diameters immediately after the operation, because the dilated sinotubular junction is reduced at the level of the transverse aortotomy by plicating it on the crest of the porcine noncoronary sinus of Valsalva—which is kept intact—and between the left and right coronary sinuses of Valsalva. The constancy of this correction over the first postoperative year, as shown in Fig 4, proves that the patient's aortic root is completely adapted to the physiologic geometry of the porcine aortic root, which almost entirely preserves its shape, as in a root inclusion technique. This plication of the sinotubular junction, performed particularly on the crest of the noncoronary sinus at the level of the aortotomy, which is located 2 mm above the sinotubular junction, obviates the need for supplementary wedge tailoring of the native noncoronary sinus. Moreover, contrary to Westaby's remark, the article provides all detailed measurements of the aortic anulus and sinotubular junction diameters in Table II and Figs 3 and 4.
I make no claims to being the first surgeon to emphasize that dense aortic root calcifications and low takeoff of the native coronary arteries constitute major drawbacks for stentless valve implantation. Conceivably, rotating the right porcine sinus toward the noncoronary sinus is an alternative option to prevent the valve cloth from bulking under the right coronary ostium located close to the aortic anulus. However, I do not like to place an outflow suture line between the aortic anulus and the right coronary ostium if the space between them is too small, because doing so would render the sewn glutaraldehyde-preserved tissue too close to the coronary ostium, precisely judged inadvisable by Westaby.
Westaby emphasizes that the stentless bioprosthesis is oriented according to the relative positions of the porcine and patient coronary ostia in conventional techniques. I wonder whether this adjustment is done at the inflow insertion level, because in all published articles, including that of Westaby and associates, 2 the stitches are placed such that the patient commissures are aligned with the porcine commissures. I believe this may result from the tendency to consider the disposition of human coronary ostia as being in the center of the left and right sinuses of Valsalva and thereby similarly mispresenting them in technical illustrations. In reality, this is erroneous because of the wide variation in the angle (90°-180°) between human coronary ostia, in the disposition of the ostia with respect to the commissures and the aortic anulus, and to the great variability of aortic root geometry in patients with severe long-standing aortic stenosis. Unfortunately, as I recently mentioned in a letter to the Editor 3 regarding a case report published by Uemura and coworkers, 4 the fundamental mistake is trying to properly adjust the patient's coronary ostia to the left and right porcine scallops only at the outflow insertion level without taking into account their proper adjustment at the inflow insertion level. Attempts to adjust them by keeping the outflow suture line away from the coronary ostia, particularly in abnormally located coronary ostia, can result in distortion of the commissures of the prosthesis and/or in the creation of longitudinal crimps on the porcine noncoronary sinus. I observed that these distortions and crimps of the outflow part of the porcine aortic root became more important when the angle between the coronary ostia surpassed 170° or when the ostia were located close to the commissures, even when properly adjusting the coronary ostia at the inflow insertion level and keeping the noncoronary sinus intact. For this reason, I would be interested to know the fate of these improperly adjusted valves at the inflow insertion level at midterm and long-term follow-up. 5 I believe that it would be advantageous to compare the deterioration rates of stentless valves implanted in aortic roots with normal and abnormal coronary angles, as well as with respect to the disposition of the commissures and the aortic anulus.
Contrary to Westaby's impression, this technique does not overcomplicate, but rather facilitates the implantation of the Freestyle valve, especially for less experienced surgeons. I have noticed this in workshops, during which some surgeons say they feel more security and comfort with this technique. Measurements of angles are performed for investigational purposes to reinforce the utility and advantage of this technical concept with regard to the coronary ostia, but they are not required for the valve implantation procedure. Angles greater than 170° and less than 130° could be easily estimated on visual inspection of the aortic root.
In our technique, the prosthesis is sewn 3 mm away from the coronary ostia as in the root-inclusion and full root techniques. We have not encountered any complications related to coronary ostia thus far, over a mean follow-up period of 3 years in more than 150 cases of stentless valves and aortic homografts implanted by the same technique. On the other hand, the inflow adjustment of the insertion level allows for perfect alignment between the U-shaped portions of the porcine aortic sinuses and human coronary ostia and thereby reduces the trimming of left and right porcine sinuses to a degree just needed to keep the outflow suture line far enough from the coronary ostia. This re-establishes a more physiologic anatomy to the dilated native aortic root by essentially preserving the global geometry of the porcine aortic root. Filling the space between the recipient and porcine noncoronary sinuses with tissue glue allows the recipient's usually dilated noncoronary sinus to take on the geometry of the porcine sinus by eliminating the dead space between them.
Finally, I choose a prosthesis according to the largest sizer that can pass through the anulus, because I believe the prosthesis fits better in the anulus, hence avoiding both the formation of crimps at the inflow insertion level and the presence of excessive porcine tissue that would need to be adjusted at the outflow insertion level when using an oversized prosthesis.
I hope that this technical concept, along with our observational data, proves sufficiently provocative to stimulate surgeons interested in implanting stentless valves by offering them greater facility at the coronary ostial level.
12/8/113009doi:10.1067/mtc.2001.113009
References
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