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MMCTS
(September 15, 2008). doi:10.1510/mmcts.2006.002329 Copyright © 2008 European Association for Cardio-thoracic Surgery
Procedure Surgery for supravalvular aortic stenosis – the three-patch techniqueDepartment of Pediatric Cardiothoracic Surgery, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands * Corresponding author: Tel.: +31-71-5262348; fax: +31-71-5248110. m.g.hazekamp{at}lumc.nl
The objective of this paper is to describe the three-patch technique for repair of supravalvular aortic stenosis (SVAS). Supravalvular aortic stenosis is a rare malformation as a result of an abnormal thickening of the aortic wall. SVAS may present in two forms: a localized form (affecting only the aortic sinotubular junction) and a diffuse form, where the aortic arch and its side branches are also affected. Since 1960, multiple surgical techniques have been described with the aim of relieving the aortic narrowing and restoring the aortic root. We present the three-patch technique as originally developed by Brom. After transection of the aorta at the sinotubular junction, three longitudinal incisions are made into the three sinuses. The aortic root geometry is then restored by placement of three separate patches of autologous pericardium in the opened sinuses. Brom's technique provides a complete and symmetric restoration of the aortic anatomy. The technique is illustrated by angiographies, surgical drawings, videos and a review of the literature. The results of the three-patch technique are good and our long-term experience will be described.
Key Words: Congenital heart disease • Supravalvular stenosis • Three-patch surgical repair
Congenital supravalvular aortic stenosis (SVAS) is an uncommon anomaly that is defined by the presence of a narrowing situated at the level of the sinotubular junction. Histology reveals an abnormal thickening of the aortic media, as well as an intimal hyperplasia of the aortic wall. It is presented as a characteristic lesion in patients affected by Williams-Beuren syndrome, but SVAS can also be found in non-syndromic familiar forms or sporadic cases. In cases with Williams syndrome, SVAS can be associated with peripheral pulmonary artery stenosis [1]. SVAS is the result of a spontaneous or inherited microdeletion in the elastin gene, localized at chromosome 7. As a consequence of this genetic mutation, irregular and pathologic elastic fibers form the aortic wall. Besides, a reduced elastin content in the artery wall has been reported. Abnormal media thickening of the aortic wall is the result of a defective formation and deposition of the elastin [2, 3]. It has been described how a reduction in the elasticity of great arteries may increase the stress in the artery wall, and this fact leads to an excessive collagen deposition in the aortic media and to a hypertrophy of smooth muscle cells. The result is a circumferential narrowing at the sinotubular aortic junction and an obstructive arteriopathy that can include aortic arch, major arteries and pulmonary arteries [4, 5]. Commonly associated lesions may be located at the aortic valve (in some series, leaflet thickening is presented in 30% of cases and leaflet adhesion in 45%) and in the coronary arteries (49% reported in previous literature, corresponding with obstruction, dilation or structural wall changes) [2, 6, 7]. Two major patterns of supravalvular aortic stenosis are described: the localized form and a diffuse form. In the localized supravalvular aortic stenosis, the malformation consists in a supravalvular narrow ring at the aortic sinotubular junction. The rest of the aortic anatomy is preserved. In contrast, the diffuse form is a more severe form of presentation where, besides the presence of a supravalvular aortic narrowing, there are anatomical malformations located in the ascending aorta, aortic arch, arch vessels and pulmonary arteries [2, 8, 9].
Diagnosis Electrocardiography can show signals of myocardial ischemia and left ventricular hypertrophy. Besides, the aortic leaflets in SVAS are exposed to a decrease in mobility and a higher pressure which may lead to accelerated aortic valve degeneration. Echo-Doppler cardiography shows the circumferential narrowing in the sinotubular aortic junction or the hourglass stenosis. Doppler studies are useful to evaluate valvular lesions that may be associated to the supravalvular aortic stenosis [10]. Angiography is only required when suspicion exists of obstruction of aortic arch, arch vessels or pulmonary artery stenosis (Photos 1 and 2).
Patients with SVAS may present with angina pectoris as a result of occlusion of the (left) coronary ostium by the valve leaflet. As the free edge of the cusp is fixed in a position superior and close to the coronary ostium, obstruction may occur.
History Several surgical techniques have been described since the first supravalvular aortic stenosis description appeared. The original simple patch enlargement of sinotubular junction at the non-coronary sinus of Valsalva, proposed in 1961 by McGoon and associates, was the first surgical technique described to widen the supravalvular stenosis. This procedure became the standard surgical procedure until the description of more extended aortoplasties. Multiple surgical options of treatment of supravalvular aortic stenosis have been suggested [11, 12]. Doty, Polansky and associates, in 1977, described an extended aortoplasty that involved two sinuses instead of one, using a bifurcated patch (Y-shaped Dacron patch). In this case, an inverted Y-shape incision is made into the non-coronary sinus and the right coronary sinus and the bifurcated patch is placed. This technique appeared as a more symmetric enlargement of the aortic root, but the narrowing above the left coronary ostium remains unsolved by this extended aortoplasty [13–15]. Some years later, Brom (1988) described a new surgical approach that enlarged all three sinuses of Valsalva [16]. In this procedure, the aorta is transected just above the stenosis, and three longitudinal incisions are made in each sinus of Valsalva and three pericardial patches are inserted. Brom's technique can be modified in case an enlargement of the more distal ascending aorta is needed (Schematic 1) [6].
Myers and coworkers reported an aortoplasty that does not require the use of any prosthetic patch. The aorta is transected at the level of the stenosis. Three longitudinal incisions are made. Three incisions are made in the ascending aorta corresponding with the aortic valve commissures. Then, an end-to-end aortic anastomosis is made as a sliding plasty. A characteristic of this technique is the absence of synthetic or foreign material [18]. Chard and Cartmill, in 1993, described an aortoplasty where the SVAS is resected and an end-to-end anastomosis between the proximal and distal aorta is made [19]. Problems may appear in extended narrow aortic ring, where the excision of the thickened aortic wall can make a direct aortic anastomosis difficult. There are some disadvantages. Performing this end-to-end anastomosis requires an extensive mobilization of the aortic structures, and also, a risk of right pulmonary artery or left main bronchus obstruction exists. It is of importance to inspect the coronary ostia as especially the entrance to the left coronary ostium may be obstructed by adherence of the free edge of the valve leaflet to the sinotubular junction. Patch enlargement of the affected sinus is necessary to allow for unobstructed coronary artery flow [7, 17, 20]. In the diffuse form of SVAS, with involvement of the arch and arch vessels, extensive patch enlargement is needed and will usually require deep hypothermic circulatory arrest. Depending on the age of the patient, patches can be made of autologous pericardium, synthetic material or pulmonary homograft wall. In selected cases intraoperative placement of stents may be considered to dilate the obstructions in the arch vessels.
The Brom's three-patch technique The surgical approach is by a median sternotomy. The thymus is excised, and a correct exposition of the heart is made by opening the pericardium. First, the supravalvular aortic ring is located (Photo 3; Video 1).
Cardiopulmonary bypass, with cardioplegic arrest and moderate hypothermia are used. In those cases where the aortic lesions extended onto the ascending aorta and aortic arch (diffuse SAVS form), and a surgical restoration is required, deep hypothermia and total circulatory arrest are added to the procedure. First of all, the aortic restoration starts with a complete transection of the ascending aorta at the level of maximal stenosis (Schematic 2, Photo 4).
A longitudinal aortic incision is then made in each one of the three coronary sinuses, perpendicular to the line of transection (Schematic 3) [6]. First, an incision into the non-coronary sinus is made, which improves the exposure to perform the incisions in the other two coronary sinuses. The depth and direction of the incisions depend on the characteristics of the supravalvular aortic stenosis, and the place where the coronary orifices are located (Video 2).
Once the aortic tract is wide open, the aorta is prepared for anatomical restoration. In our hospital, untreated autologous pericardium is the material of choice used to obtain the three rectangular patches needed for the extended aortoplasty. Historically, other materials have been used such us glutaraldehyde-treated pericardium, dura mater or synthetic materials. The three rectangular patches are inserted into place (Schematic 4). They are sutured into the three longitudinal incisions previously made in each aortic sinus (Video 3).
Care is taken to design the correct size of the patches. Special attention to the patch width is needed to avoid extension of the commissures and possible aortic valve insufficiency (Videos 4 and 5).
In selected cases, where the supravalvular aortic stenosis involves the ascending aorta, it may be necessary to add an extra pericardial patch in the distal aorta (Schematic 1). After suturing the three patches in place (Video 6), an end-to-end aortic anastomosis is made connecting the reconstructed aortic root to the ascending aorta (Schematic 5).
Once the restoration is completed, and the aorta is completely sutured, the left heart is de-aired and aortic cross-clamp is removed (Video 7).
Postoperative transesophageal echocardiographic assessment is always performed. A complete evaluation of the aortic valve, left ventricle outflow tract gradients and ventricle function is useful to evaluate the final result of the aortic restoration.
From 1983 to the present, 15 patients with SVAS have been operated in our institution, of whom 4 (26.6%) had a diffuse form of SVAS with aortic arch obstruction. Eight patients (53.3%) were male. Mean age at operation was 5.1 years±4.71 years (mean±S.D.). Eight patients (53.3%) had Williams syndrome, and two patients had another familiar form of SVAS. The aortic valve was tricuspid in all cases operated. No aortic regurgitation was observed preoperatively. Associated lesions described were: stenosis of the arteria anonyma (4/15, 26.6%), peripheral pulmonary stenosis (3/15, 20%), obstruction of supraaortic vessels (3/15, 20%), coarctation (2/15, 13.3%), aortic valve stenosis due to commissural fusion (1/15, 6.6%) and mitral valve regurgitation (1/15, 6.6%). All had repair by the three-patch technique. In the majority of patients untreated autologous pericardium was used. This is our current policy. Only in one patient a homograft was used as patch material. Several patients had associated repair of aortic arch obstruction (4/15, 26.6%), aortic coarctation (2/15, 13.3%), proximal obstruction of aortic arch vessels (2/15, 13.3%), aortic valve stenosis (1/15, 6.6% – a commisurotomy was carried out), or mitral insufficiency (1/15, 6.6% – a mitral valve replacement was performed). There was no mortality. One patient underwent early reoperation (eight days after the first operation) for coarctation repair. No patient was reoperated at a later stage. There were no reoperations for aortic arch obstruction. Follow-up time was 113.2±81.14 months (mean±S.D.). It was complete for all patients including echo-Doppler studies. Mean gradients at last follow-up were no more than 10 mmHg. Aortic valve insufficiency was absent or trivial in 13 patients (86.6%) and mild to moderate in 2 (13.4%).
The three-patch technique for repair of supravalvular aortic stenosis designed by Brom, provided in the past a new concept of restoration of the aortic tract that nowadays continues to be the ideal model to repair the supravalvular aortic stenosis. The advantages of this technique in contrast to other techniques reported in literature are multiple. It provides a more symmetric reconstruction and less distortion of the aortic root and the ascending aorta [6, 15]. Autologous pericardium has never resulted in aneurysm formation and appears to behave as normal thickness vascular tissue. Although there are no recent studies, and a significant difference to other techniques could not been demonstrated in our publication of 1999, the experience of our group and that of others endorses the three-patch reconstruction as a safe and efficient surgical procedure with good long-term follow-up results, and a very low reoperation rate [6, 9]. A narrow or obstructed entrance to the left coronary sinus and thus to the left coronary artery is not uncommon in SVAS. It may lead to cardiac ischemia and is potentially life-threatening. The left coronary sinus is not widened by the one, two or Y-patch techniques. Only the three-patch technique or the sliding plasty as described by Myers, allow for effective restoration of the left coronary sinus [6, 18]. The Myers technique has the advantage of not using any patch material. However, we believe that Brom's three-patch technique may be technically easier while the individual patches can be designed in such a way that aortic root restoration will be optimal. Care should be taken not to widen the patches too much as this may lead to loss of aortic valve coaptation and valve leakage.
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Summary
Introduction
