Aortic Valve Surgery - The Third Millennium

We all know the monumental contribution of Alain Carpentier to the understanding of the pathology of the mitral valve, its function and therapeutic implications. There were also a number of surgeons who have expanded on the original idea (Duran, Cosgrove and others) and made contributions in this field. We know today unequivocally the superiority of mitral valve repair over replacement. Unfortunately, there is no similar understanding of the function of the aortic valve, and as a result we are experiencing chaos. There is no universal direction we should go in order to best serve our patients. For some reason we have elected to violate the fundamental principal of the progress of medicine, which is based on the understanding of human physiology. We have never attempted to outperform nature; for instance we have never attempted to build an artificial kidney which would be superior to the human one. We have never attempted to have the camera surpass the human eye. No matter how many pixels we put in the digital camera, we will never surpass the human eye in seeing the sunrise the way we do.

We have lost our way in aortic valve surgery. We have made a lot of valves but we have never followed in general the principals dictated by nature. For some reason, there are only few surgeons in the world who pay attention to the very complex physiology of the aortic valve. As a result, we are trying to do something which is unprecedented in medicine. We are trying to outperform nature. Wouldn't it be logical to conform to physiology? This has been formulated and pursued by only a few outstanding surgeons (David, Duran, Ross, Yacoub among others).

The future in the improvement of aortic valve surgery lies in the understanding of the complexity of the aortic apparatus. We cannot argue stentless versus stented porcine valve. We cannot make paradoxical statements that a pig is a pig, because a pig in a different environment may have less or more stress so that the longevity of this valve will be altered. We cannot make a statement that "the orifice of the aortic valve has no importance to the patient's survival" or ignore patient-prosthesis mismatch. If that would be true, we could take the valve from the mouse and implant to the elephant. (I wonder how that would work.) We cannot make those absurd statements. Aortic valve disease is not only a story about the valve but relates also to the myocardium. Isn't it logical that creating an aortic valve that will mimic the natural one the closest will make recovery of the myocardium most effective?

We cannot violate the principals governing the aortic valve - as a result there is very little place for stented valves, except in patients in whom it is irrelevant because their life expectancy is limited. In 1967 Donald Ross introduced a procedure which he felt at the time would be primarily applicable to children. Now we know it is more far-reaching and extends beyond children. I think the hemodynamic benefit of the operation that bears his name is obvious and well-documented. However, this is an operation for few surgeons. In a sense it is unlike the mitral valve, since in mitral valve surgery an understanding of the pathology and execution of the procedure is relatively straight-forward as a result of guidelines well-illustrated by Carpentier. With the aortic valve, however, the pathology is obvious but function restoration of the valve can be daunting. I do believe the Ross procedure cannot be treated as a hobby - it is a difficult procedure, and the operation is intolerant to the smallest error of judgment or technique, and the price is often a young life. As a result a procedure which should be done by only a few well-trained surgeons becomes the subject of criticism. It is not the same with a stented versus stentless porcine valve?

We should not argue whether we should learn subcoronary or root replacement procedure, but should only make decisions based on the pathology rather than tailoring the procedure to the comfort of the surgeon. The implantation of the homograft is usually as the root replacement regardless of the pathology for this very reason. The use of aortic homografts has plateaued or may have decreased in the recent past since there is concern about calcification of the aortic wall and subsequent difficulties with re-operation. The truth is that the root replacement is rarely indicated and most homografts should be implanted in a subcoronary position. I think Dr. Doty would agree with me.

I would encourage surgeons and the people who are involved in research to focus on understanding the very complex function of the aortic apparatus. I am grateful to my teachers, and in particular Drs. Loop and Lytle, for instilling in me these principles as outlined above, along with discipline, perseverance, and attention to detail. It has become a life-long commitment to perfection reflecting the tradition of the Cleveland Clinic pursuit of excellence.