Ann Thorac Surg 2006;81:1610-1611
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Invited commentary
Patrick McCarthy, MD
Division of Cardiothoracic Surgery, Northwestern University, 201 East Huron St, Galter 10-105, Chicago, IL 60611-3056
(Email: pmccart{at}nmh.org).
Back to the future? Although highly successful, aortic valve replacement still has a host of problems that need to be managed. These problems include the following: ascending aortic calcification that can embolize or complicate aortic cross clamping or aortotomy closure; a small aortic annulus that may require patch enlargement (a more complex operation with higher risks), or the possibility for patient prosthesis mismatch; possible peri-valvular leak depending on the quality of the aortic annulus and the experience of the cardiac surgeon; heart block; fibrosis and calcification from radiation heart disease; and various problems in patients with patent coronary bypass grafts such as managing proximals attached near the aortotomy, avoiding a left internal mammary artery graft that may be in the midline, and obtaining adequate myocardial protection. Oftentimes primary aortic valve replacement is a low-risk operation. However, elderly patients with comorbidities that lead to high operative risk stimulated the development of percutaneous aortic valve replacement. Just as the advent of stenting pushed surgeons to consider more creative ways to perform coronary artery bypass, the advent of percutaneous valve techniques has stimulated surgeons to consider alternative approaches to conventional aortic valve replacement. The advantages of the aortic valve bypass as described in this article are to avoid the problems of conventional aortic valve replacement in high-risk patients. A strong advantage over percutaneous aortic valve approaches is the ability to use a known commercially available prosthetic valve with a strong track record for durability. Ideal candidates for this type of approach could include patients with ascending aortic calcification, patients who require complex reoperations, and patients with a small annulus. With new strategies and new technologies this can become a very attractive alternative for a significant percentage of patients undergoing isolated aortic valve replacement (i.e., 5.8% in Gammie and colleagues' [1] experience). However, current state of the art is to modify existing conduits and valves adapted to fit this very different situation. The potential problems with the aortic valve bypass approach include pseudoaneurysm as described in their article, bleeding due to lack of control of the left ventricular (LV) apex, difficulty with the aortic anastomosis in the descending aorta due to extensive calcification of the descending aorta, kinking of the conduit because it is either too long or too short, and theoretical dislodgement of an LV apical thrombus that may not be visible by preoperative or intraoperative imaging. Should cardiopulmonary bypass be required, then it would typically employ retrograde perfusion, either from the femoral artery or a side graft from the aortic graft as described in this article, with a risk of embolization. Theoretical problems may include the nonphysiologic flow from the LV apex to the descending aorta. However, surgeons have grown used to a very successful operation that does not provide physiologic flow in coronary artery bypass. In the same way, bypassing the native aortic valve provides a clever way to work around difficult situations in some of our elderly and otherwise sick patients. With more than a 20-year history in patients, this would seem to be a strategy that has long-term durability and is not something that one would expect to see reproduced with any of the percutaneous aortic valve technologies. For this reason, surgeons should be interested in resurrecting this technique and looking forward to ways to simplify the operation and bring this to a more routine clinical care.
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- Gammie JS, Brown JW, Brown JM, et al. Aortic valve bypass for the high-risk patient with aortic stenosis Ann Thorac Surg 2006;81:1605-1611.[Abstract/Free Full Text]
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