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MMCTS
(November 10, 2006). doi:10.1510/mmcts.2006.001982 Copyright © 2006 European Association for Cardio-thoracic Surgery Procedure Valve sparing aortic replacement – root remodelingDepartment of Thoracic and Cardiovascular Surgery, University Hospitals of Saarland, D-66421 Homburg/Saar, Germany * Corresponding author: * Tel.: +49-6841-1632000; fax: +49-6841-1632005 E-mail: h-j.schaefers{at}uniklinikum-saarland.de
Aortic root remodeling restores aortic root geometry and improves valve competence. We have used this technique whenever aorto-ventricular diameter is preserved. The operative technique is detained in this presentation. As a result of our 10-year experience with root remodeling we propose this operation as a reproducible option for patients with dilatation of the aortic root.
Key Words: Aortic root • Aortic valve sparing • Aortic valve repair • Aortic dilatation
In the past 15 years valve-preserving aortic replacement has evolved into an increasingly accepted alternative to composite replacement of aorta and valve. Preservation of the native aortic valve has the obvious advantage of avoiding the need for anticoagulation, and there is increasing evidence that it minimizes the incidence of valve-related complications. Two basically different principles of valve-preserving aortic replacement are currently used, and minor modifications have been proposed for both. Remodeling of the root was originally designed by Sarsam and Yacoub [1], and it has been demonstrated to restore root geometry and improve aortic valve competence. Reimplantation of the native valve within a vascular graft was designed by Tirone David [2], and it has also been shown to normalize aortic root dimensions and restore valve function. We have employed this technique for more than 10 years and have been very satisfied with the clinical results [3, 4]. Root remodeling in our hands has had an advantage over the reimplantation procedure of being less complex and time consuming. There is also clinical and experimental evidence that remodeling leads to better preservation of aortic cusp motion, which may translate into better long-term durability of the valve [5, 6]. A limitation of this procedure is the fact that it does not alter the diameter of the aorto-ventricular junction. Root remodeling is thus not a good option in patients with typical anulo-aortic ectasia. Despite the ongoing controversy regarding the relative roles of remodeling versus reimplantation it has to be kept in mind that any reconstructive operation on the aortic root may alter aortic valve geometry and function. Thus, it is probably less important which but rather how valve-preserving aortic replacement is performed in order to reach the goal, i.e. elimination of aortic pathology and normal (or near normal) function of the aortic valve.
Patient selection
There has been increasing evidence in the last years that remodeling may not be a good operation for every patient with a dilated aortic root. Patients with connective tissue disease commonly have a large so-called annulus, better termed aorto-ventricular junction. Root remodeling will not be able to reduce the size of the aorto-ventricular junction, and we limit its use to a diameter of <30 mm at aorto-ventricular level, choosing valve reimplantation for individuals with bigger sizes. Valve preserving surgery does not appear reasonable or appropriate in patients who have significant calcification of the aortic cusps or multiple fenestrations that can be expected to diminish long-term cusp stability. Root remodeling is not justified for ascending aortic aneurysm which spares the root and only starts at the level of the commissures. In addition, the role of valve sparing surgery in the elderly patient may be discussed controversially. On the other hand, preservation of the aortic valve has been shown to be associated with a low incidence of endocarditis, and this ultimately may also be an argument for preservation of the native aortic valve in the elderly patient.
Much of the necessary information can be gathered from the preoperative aortogram (Video 1) or transthoracic echocardiogram. A transesophageal echocardiogram will help to determine the diameter of the aorto-ventricular and sino-tubular junction.
We prefer a standard median sternotomy, aortic and right atrial cannulations are used for connection to cardiopulmonary bypass. After the proximal aortic arch and the brachiocephalic trunk are mobilized, it is most often possible to place a clamp just beneath the trunk. The aorta is opened by a longitudinal incision, and cardioplegia is given directly into the coronary ostia. For optimal exposure, the aorta is completely transsected 5 to 10 mm above the commissures. Stay sutures are placed. We routinely measure the size of the aorto-ventricular junction using standard valve sizers (Video 2).
If the aorto-ventricular junction is 29 mm or less, and sino-tubular junction is more than 33 mm, we proceed with root remodeling. Mobilization of the aortic root down to the lowest point of the sinuses is an important step of the operation (Video 3).
We have a pragmatic approach in choosing graft size and take a graft of approximately 1 to 2 mm smaller than the diameter of the aorto-ventricular junction. In order to create three symmetric tongues short incisions are made on one end of the graft. We ascertain symmetry by simply compressing the graft in different directions (Video 4).
The height of the native commissures is eye-balled, and the respective incision in the graft is kept approximately 20% shorter than the estimated height of the commissure. It is always easier to simply extend the length of this incision that has to accommodate the commissure rather than to work with an incision that is simply too long. The three tongues are now cut in a configuration that resembles a sinus curve (Video 5). Wide tongues will let the remodeled root bulge more, but may also contribute to secondary dilatation of the root in the long-term course.
The graft is sutured to the aortic root, carefully following the insertion line of the aortic cusps (Video 6). We always start in the center of a sinus and work our way up to the commissures. By doing so, it is easy to accommodate the exact height of the commissure in the graft. We usually begin with the left sinus, continue with the right sinus and suture the non-coronary sinus last (Video 7).
Assessment of the aortic valve, i.e. configuration of the cusps is the most important part of the procedure once the graft has been sutured in place (Video 8). The reduction of sinus dimensions will lead to some degree of cusp prolapse. In addition, prolapse may be pre-existent or aggravated by the operation. Initially we felt that only asymmetric cusp prolapse had to be corrected. We have now taken on the approach of trying to normalize the configuration of all cusps. In order to have an easy and reproducible indicator of prolapse or adequate cusp configuration we have chosen to measure the effective height of each cusp, i.e. the height difference between free margin and aortic insertion.
An effective height of 8 mm measured with a calliper intraoperatively corresponds to a similar height on postoperative echocardiograms and will result in an almost normal configuration of the aortic cusps (Video 8). In order to achieve this height the free margin is shortened by plication sutures using 5/0 or 6/0 Prolene. Once cusp configuration has been adapted, the aortic valve is checked for any residual asymmetric prolapse. This is corrected if found (Video 9).
Reimplantation of the coronaries is done in a standard fashion (Video 10). We always keep the openings in the graft relatively small, that is approximately the size of the coronary ostia. Finally, the aortic graft is trimmed to adequate length and anatomized to the ascending aorta. The heart is de-aired, coronary circulation resumed. While the degree of LV-distension and pulsatility of arterial blood pressure tracing on full bypass provide some thoracic aortic valve function, it is of paramount importance to check every repaired aortic valve by transesophageal echocardiography. In this instance there is almost normal configuration of the aortic valve with trivial aortic regurgitation (Video 11).
From October 1995 until April 2006, 262 patients underwent root remodeling for aortic root aneurysm with or without significant aortic regurgitation. The mean age was 60±15 years. Emergency surgery for acute aortic dissection was carried out in 43 patients. Valve anatomy was tricuspid in 182, and bicuspid in 80 patients. Cusp pathology was additionally corrected in 158 patients (60.3%). Follow-up was complete in 99%. Cumulative follow-up was 971 patient-years with a mean of 3.9±2.6 years.
Hospital mortality was 3.8% (10/262; elective surgery: 3.2%; emergency surgery: 7%). One patient developed endocarditis two months postoperatively and underwent valve replacement. Neurologic complications were observed in three patients after emergency surgery (paraparesis: n=2, cerebral infarction: n=1). Another patient suffered a PRIND after elective surgery. Freedom from AI
In patients with dilatation of the aortic root with or without aortic regurgitation, both root remodeling and reimplantation of the aortic valve restore root geometry and valve function. Because of a higher long-term failure rate of remodeling in the experience of some groups [7, 8], reimplantation has recently been favored. Reimplantation indeed has led to stable long-term results, most likely due to the stabilization of the aortic annulus inside the vascular graft [7–9]. It is, however, the more complex procedure requiring more extensive dissection of the aortic root and significantly longer myocardial ischemic times [8]. The rigidity of the aortic root results in a less physiologic movement pattern of the aortic cusps with increased dynamic stress on the valve cusps [10]. Aortic root remodeling is generally considered the simpler and also more physiologic operation. Dissection of the aortic root is less extensive and complex and usually not associated with complications [11]. It restores an almost physiologic motion pattern of the aortic cusps by leaving physiologic distensibility to the aortic annulus [10]. Because of that, progressive dilatation of the aortic root on the level of the aorto-ventricular junction with consecutive aortic regurgitation may occur. Several groups have seen a higher incidence for re-operation and therefore favor valve reimplantation [7, 8]. An overview of the essential features of both surgical techniques is visualized in Table 1.
In our experience with 262 patients we have seen very stable long-term results with a freedom from re-operation of 96% after 10 years. We have observed dilatation of the aorto-ventricular junction only once. We have learned, however, that reduction of the sino-tubular junction may induce a proportional prolapse of the cusps. Correction of cusp prolapse seems to be of paramount importance for long-term aortic valve competence and stability [12]. With experience, root remodeling can be used as part of an aortic valve procedure in the setting of root dilatation and almost any non-calcified aortic valve. It is important, however, to inspect the cusps carefully. Fenestrations in two or three cusps may make this valve not an ideal substitute for repair with good long-term results. Stabilization of more than just one or two fenestrations with pericardial patches may require a long myocardial ischemic time and distort cusp geometry. As always in surgery, exposure makes all the differences between an easy or a difficult operation. For this purpose, stay sutures are important. Their direction and their tension for individual steps of the operation are varied in order to provide optimal exposure. It is of utmost importance to remember that any change in sinus dimensions will automatically alter the configuration of the aortic cusps. In addition, some degree of cusp prolapse is often pre-existent once the patient comes with more than aortic regurgitation grade II. For these two reasons never trust that root remodeling alone will result in a competent aortic valve with a normal configuration. Always check the configuration of aortic valve after completion of remodeling. In case of doubt transsect the Dacron graft 1 cm above the height of the commissures in order to have better exposure. Subsequent graft to graft sutures are easy to do.
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Summary
Introduction
II was 91% at 5 years and 90% at 10 years. Eight patients required reoperation: in five patients the valve was replaced, in three patients re-repaired. Freedom from reoperation was 96% at 5 and 10 years. Freedom from valve replacement was 98% at 5 and 10 years. 
