Departments of Cardiology and Cardiac Surgery,
Sree Chitra Tirunal Institute for Medical Sciences and Technology,
Thiruvananthapuram

Background: Supravalvar aortic stenosis is the rarest of left ventricular outflow obstructions. Data on this rare entity from India are scarce.

Methods and Results: We retrospectively analyzed the data of 15 patients (13 males, mean age 15.5±10.18 years) with a diagnosis of supravalvar aortic stenosis confirmed by cardiac catheterization. Five patients had morphological features of Williams’ syndrome. One patient had diffuse while the rest had discrete type of supravalvar aortic stenosis. Five patients did not have any associated lesions. A 9-year-old male had an ascending aortic aneurysm, and 3 patients had associated peripheral pulmonary artery stenosis. One child had a subaortic ventricular septal defect, and another had severe mitral regurgitation. Twelve patients had electrocardiographic evidence of left ventricular hypertrophy. Three patients had mild aortic valvar stenosis while 2 had aortic regurgitation. Six patients had dilated coronary arteries. Two patients with supravalvar aortic gradients of 20 and 40 mmHg were kept on close follow-up. One patient was not willing to undergo surgery while the other is awaiting surgery. Eleven patients underwent surgical correction. Dacron or pericardial patch aortoplasty was done in all the patients. In addition, one patient each underwent pulmonary artery plasty, ventricular septal defect closure, repair of ascending aortic aneurysm, and mitral valve replacement. The patient with diffuse type of supravalvar aortic stenosis underwent augmentation aortoplasty. Two patients died perioperatively. One was lost to follow-up. Two had moderate residual gradients. The rest of the patients were in New York Heart Association functional class I on follow-up of 6.3±4.7 years.

Conclusions: Repair of supravalvar aortic stenosis by single sinus aortoplasty is safe and produces good results. (Indian Heart J 2003; 55: 49–54)

Key Words: Supravalvar aortic stenosis, Williams’ syndrome, Aortoplasty

Supravalvar aortic stenosis is relatively rare and the least common of the congenital LVOT obstructions.1 The patients can be classified into three groups according to the mode of presentation.

1. Nonfamilial sporadic cases with normal facies and intelligence

2. Autosomal dominant familial cases with normal facies and intelligence3

3. Williams–Beuren's syndrome2–4 with characteristic elfin facies and mental retardation—nonfamilial.

Morphologically, SVAS can be categorized into three types.

1. Hourglass type: the most common type, characterized by a constricting annular ridge at the superior margin of the sinus of Valsalva

2. Membranous type: produced by an intra-aortic fibrous/ fibromuscular circular/semicircular diaphragm with a central opening

3. Hypoplastic type: with uniform hypoplasia of the ascending aorta which may extend into the arch vessels.

Supravalvar aortic stenosis is unique among LVOT obstructions because, among systemic vessels, the coronary arteries alone are exposed to high systolic pressures,⁵ which lead to dilatation, tortuosity and premature atherosclerosis of these arteries, thus making the patient susceptible to sudden cardiac death before and after repair. The coronary ostia may be obstructed by the overhanging thick sinus rims as well as bound-down aortic cusps. This more commonly occurs in the left sinus, but can also occur in the right. Also, the free edges of the aortic cusps (which are thickened in one-third of patients) may be adherent to the intraluminal supravalvar aortic ridge. This contributes to LVOT obstruction, interferes with coronary blood flow, and is also responsible for the associated aortic regurgitation.

Five of our 15 patients had associated aortic valve anomalies. In the series by Sharma et al.,⁶ 25% of the patients had a bicuspid aortic valve,12% had aortic regurgitation, 11% had valvar aortic stenosis, and 10% had subvalvar stenosis. In the series of 13 patients by Braunstein et al.⁷ one patient had subaortic obstruction. Williams–Beuren’s syndrome^2–4 is associated with a microdeletion in the chromosomal region 7q11.23 encompassing, among others, the elastin gene. The syndrome is routinely confirmed by detecting elastin hemizygosity by fluorescence in situ hybridization (FISH). Previous reports suggest that hemizygosity of the elastin gene is responsible for the typical vasculopathy of this syndrome, namely, SVAS and pulmonary arterial stenosis.^4,5

Williams–Beuren’s syndrome is associated with the nonfamilial form of SVAS, in which there is a peculiar facies (small chin, large mouth, patulous lips, blunt and upturned nose, widely set eyes with internal strabismus, epicanthic folds, broad forehead, baggy cheeks, lacy iris pattern, and malformed teeth with malocclusion), short stature, and mental retardation. Adult patients are short-statured, may have kyphoscoliosis, and may develop progressive joint limitation and hypertonia. These patients may have idiopathic infantile hypercalcemia, pulmonary artery stenosis (especially peripheral pulmonary stenosis), renal artery anomalies, tortuous retinal arteries, systemic hypertension, and gastrointestinal and urinary tract anomalies. 

In Williams’ syndrome, SVAS seems to progress rapidly while peripheral pulmonary stenosis improves with time.⁸ Associated cardiac lesions described are pulmonary stenosis (both valvar and peripheral), mitral valve anomalies with MR, and aneurysm of the ascending aorta and subaortic  obstruction. Etiologic factors proposed are idiopathic hypercalcemia, disturbance of vitamin D metabolism and calcium homeostasis,⁹ and rubella.

In our series, there were no familial cases of SVAS, but there were 5 cases of Williams’ syndrome. Of them, 2 had peripheral pulmonary artery stenosis and one had aortic valvar stenosis. Only one of these patients had hypercalcemia; however, vitamin D challenge or calcium loading tests were not done in these patients to unmask calcium homeostatic defects. Seven of the 13 patients in the series by Braunstein et al.⁷ and 14 of the 101 patients in the series by Brown et al.¹⁰ had Williams' syndrome.

The treatment of SVAS is surgical if the patient has significant gradients. SVAS is less amenable to operative treatment than either valvar or discrete subvalvar stenosis. Successful surgery for SVAS using patch graft enlargement of the noncoronary sinus of Valsalva was first reported from the Mayo clinic.¹¹ After that, many series on surgical results in patients with SVAS have been reported.^6,10–18

The discrete type of SVAS is more amenable to surgery than the diffuse type. In the discrete type, aortotomy is done above the valve, and the incision carried into the right or noncoronary sinus of Valsalva. The intimal shelf is then resected and a diamond-shaped pericardial/dacron patch incorporated into the incision to enlarge the aortic diameter to normal.

In the single-center experience of SVAS from the Texas Heart Institute, 32% of the patients had discrete type of SVAS, and were treated with simple patch aortoplasty (placing a diamond-shaped patch across the sinus rim in the noncoronary sinus of Valsalva) with good results and only 4% mortality. Though this operation was effective in relieving the pressure gradients, it did nothing to rebuild/remodel the diseased aortic root. Doty et al.¹⁹ have proposed bisinus repair by extending a bilobed patch into both the noncoronary sinus and right coronary sinus for a wider and anatomically more symmetrical repair, even in cases with discrete stenosis.

Surgical treatment options for the diffuse form of SVAS are less well defined. It may become necessary to replace or widen the entire hypoplastic aorta with an appropriate prosthesis.^16,17 Extended patch aortoplasty and apicoaortic conduits are the procedures that have been tried. Sharma et al.⁶ have treated two patients with the diffuse variety of SVAS with another technique: extensive endarterectomy of the ascending aorta and arch, with patch aortoplasty extended into the aortic arch. Since the morphologic defect in SVAS involves the media and intima, it seems logical to remove these by endarterectomy.⁶

Only 1 of our patients had the diffuse variety of SVAS (6.66%), compared with 15% of patients in the series by Sharma et al.⁶ In the series by Brown et al.,¹⁰ 28/101 patients had the diffuse variety of SVAS, and they were treated with either an apical aortic conduit or extensive endarterectomy with patch aortoplasty, with encouraging results. In the series by Braunstein et al.,⁷ 2/13 patients with the diffuse variety of SVAS had excellent results with bisinus patching and extending the patch to the descending aorta. 

Thirty-three patients in the surgical series by Sharma et al.⁶ had other associated obstructive lesions of the LVOT requiring surgical correction. Though 2 patients in our series had associated valvar stenosis, this did not warrant surgical correction. Of patients with SVAS, 30% are reported to have thickened aortic valve cusps. Two patients (18%) developed mild AR postoperatively in our series. The exact incidence of AR in the series by Sharma et al.⁶ is not clear. However, the incidence of 44% of new AR in the series by Braunstein et al.⁷ is much higher.

Four patients in our series had associated cardiac lesions, which required surgical correction. PA plasty was done in 1 of our patients. There were no cases which required PA plasty in the Braunstein series,⁷ while 1 patient required PA plasty in the series by Sharma et al.⁶ One patient in the series by Sharma et al.⁶ had pseudoaneurysm of the ascending aorta, while 1 of our patients had an aneurysm of the ascending aorta requiring aneurysmorrhaphy.

We had 2 early deaths due to bleeding (18.18%) but no late deaths at a mean follow-up of more than 6 years.

None of our 11 patients required reoperation at a mean follow-up of more than 6 years. In the series by Sharma et al.,⁶ 22% of the patients required reoperation at some time during the follow-up period, and there were 5 late deaths in those with complex forms of the disease. We had only 1  patient with the diffuse form of the disease who underwent  extended patch aortoplasty but had moderate residual gradient on follow-up. In a large experience of 101 patients with SVAS,¹⁰ the overall survival including operative mortality was 98% at 10 years, and 97% at 20 and 30 years.

This study has several weaknesses. It was a retrospective study, and the numbers were too small to draw conclusions.

The patients did not undergo hemodynamic or angiographic study postoperatively.

We conclude that repair of SVAS by single sinus aortoplasty is safe, and produces good results.

References