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Aortic Valve, Root, Ascending Aorta and Arch
Aortic disease often simultaneously affects some combination of the aortic valve, root, ascending aorta and arch. The arteries that branch from these aortic segments require special consideration during surgery. This includes the coronary arteries, which supply blood to the heart, as well as the arteries branching from the arch, which supply blood to the head and upper body. A combination of procedures may be used in one surgery. For example, a single surgery might address the aortic valve and root with either the Button Bentall or David procedure and use open anastomsis with hypothermic circulatory arrest (HCA) for the ascending aorta and arch.
Surgical Procedures (Aortic Valve, Root, Ascending Aorta and Arch)
There are several different aortic procedures from which surgeons may choose based on their assessment of an individual patient. Procedures and techniques include:
- Button Bentall with Bioprosthesis or Prosthesis
- David Valve-Sparing Re-Implantation Procedure
- Modified Aortic Root Remodeling Technique
- Yacoub Remodeling Procedure
- Ross Procedure
- Porcine Root Replacement (Freestyle)
- Homograft Technique
The program's comfort level in performing a given procedure is always a consideration. In addition to that, the condition of the aortic valve, root, ascending aorta and arch taken together with the patient's overall health determine the surgical procedure that will be performed. Prior to surgery a strategy is developed based on what has been revealed by diagnostic testing. However, in some instances the final decision regarding the best approach is made during surgery itself.
The surgical procedures described here are the result of the continued pursuit of excellence in surgeries that may begin with the aortic valve and reach to the arch, or be limited to some subset of these structures. Generally, in order for a surgical procedure to be successful it must lend itself well to widespread usage across many surgeons and centers. Procedures that are too difficult to duplicate will not be widely adopted and will be replaced by a procedure that is easier to perform while maintaining good results. For example, if a brilliant valve-sparing operation cannot be duplicated easily, it will not be a viable procedure for use in a majority of patients.
Button Bentall with Bioprosthesis or Prosthesis
This procedure, a variation of the original Bentall procedure, is a simultaneous replacement of the aortic valve, root and the entire ascending aorta. A composite Dacron graft, which includes the new valve bioprosthesis or prosthesis, is put in place. Then the coronary arteries are implanted in the Dacron graft using aortic buttons. This procedure is typically required in severe connective tissue disorders such as the Marfan syndrome. It is also indicated whenever there is a combined dilation of the aortic root and annulus, as well as the ascending aorta.
David Valve-Sparing Re-Implantation Procedure
As its name indicates, this procedure is used for the replacement of the aortic root and ascending aorta only. The aortic valve is not replaced. However, it is re-implanted inside the Dacron tube graft, and both coronary arteries are re-attached to the Dacron. This procedure is primarily suitable for patients with trileaflet aortic valves with minimal aortic insufficiency. It may also be used in Marfan syndrome patients if their aortic annulus is not too dilated.
Modified Aortic Root Remodeling Technique
At Cedars-Sinai, this technique is used to remodel the aortic root while preserving some of the original root tissue. The entire non-coronary sinus of Valsalva is resected, and the segment of aorta between the left and right coronary arteries may also be removed depending on the coronary artery anatomy. A key difference from other procedures is that the coronary arteries are not disturbed and remain attached to native aortic tissue. The aortic valve is either intact, was previously replaced, or will be replaced during this procedure. It is potentially suitable for use in bicuspid aortic disease and some Marfan syndrome or Ehlers-Danlos patients.
Yacoub Remodeling Procedure
The Yacoub remodeling procedure uses a scalloped design to create a new aortic root out of Dacron. This scalloped shape was thought to experience less shear force and, therefore, might be expected to add more longevity and competence to valve-sparing operations. While the long-term outcomes of the original procedure have varied across centers, data regarding the latest modification to this technique is still emerging and requires careful analysis. This procedure is indicated for use in the same group of patients as the David valve-sparing re-implantation procedure.
The pulmonary valve is very similar to the aortic valve, and it has been found that a patient's own pulmonary valve may successfully be substituted for a diseased aortic valve. The surgical procedure to accomplish this is called the Ross procedure. Essentially a pulmonary valve autograft is placed in the aortic valve position, and a homograft (human donor) valve replaces the pulmonary valve. This could be an ideal operation for a young or middle-aged patient who requires aortic valve replacement. It has particular significance for children, meeting their need for a new aortic valve that will grow with them. An additional benefit of the Ross procedure is resistance to infection. However, the extensiveness of the surgery may be beyond the tolerance of those patients who are already septic and experiencing multi-organ failure secondary to infection.
The Ross procedure is more complex and technically challenging than a single valve surgery. Up to 20 percent of patients will require re-operation for degeneration of the homograft within 10 to 15 years. This procedure is appropriate in selected young patients who do not have Marfan's syndrome or a connective tissue disorder.
Porcine Root Replacement (Freestyle)
This is an easier procedure than the Ross. The porcine root is not long enough to address the ascending aorta. Therefore, added Dacron graft is required for replacement of the ascending aorta. This can be a reasonable replacement for the same indications as a homograft, as well as for a replacement of a short segment of aorta (aortic root). Possibly with the addition of a Dacron prosthesis, it can be used as an alternative Button Bentall procedure.
Homografts are the most resistant to infection, making this the preferred technique for the treatment of aortic root infection and endocarditis at Cedars-Sinai. The major disadvantages of a homograft include issues with the longevity, the size and the length. Since homografts depend on human donor availability, there is no assurance that there will be a sufficient quantity of the different sizes and lengths that may be needed. Regarding the longevity of this solution, chronic rejection causes severe calcification of the aortic wall, which becomes like a "lead pipe". To a lesser degree, the aortic valve leaflets also degenerate. Homografts may be considered for use in an elderly patient with a life expectancy less than 15 years for treatment of a heavily calcified (porcelain or egg shell) aorta in lieu of aortic valve replacement and endarterectomy of the aorta. The Synergraft, a de-cellularized homograft, theoretically has the advantage of less rejection and, therefore, less calcification and greater durability. Long-term studies are needed to confirm these theoretical benefits. A major draw back is the lack of overall availability.
Valve Repair Versus Replacement
The decision to repair versus replace the aortic valve is based on complex factors, as well as the experience and results of the particular treatment center. At Cedars-Sinai a repaired valve is expected to have a life of ten years or more (comparable to the minimum expectation for a bioprosthesis). If the repaired valve is not projected to last at least that long, the valve is replaced rather than repaired. A repaired valve could last a lifetime.
There are factors unique to each patient that must be evaluated regarding valve repair. The anatomy of the aortic valve, nature of the tissue and comfort level of the surgeon in performing the repair all are factors in the resulting durability of the repaired valve. Careful scrutiny is required for bicuspid aortic valves. In young patients where the bicuspid valve functions well with minimal calcification, or if there is localized prolapse of only one leaflet, a durable repair may be possible. However, generally for any given group of bicuspid aortic valves, approximately 75% of them cannot be repaired with acceptable durability and should be replaced. When a normal trileaflet aortic valve is present, there is greater potential for repair. Particularly during surgery for ascending aortic dissection involving a normal aortic valve, lifetime durable repairs are often possible.