AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

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• Clinical
• Differentials
• Workup
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• Medication
• Follow-up
• Miscellaneous
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Background

Supravalvular aortic stenosis (SVAS) is a fixed form of congenital left ventricular outflow tract (LVOT) obstruction that occurs as a localized or a diffuse narrowing of the ascending aorta beyond the superior margin of the sinuses of Valsalva. It accounts for less than 7% of all fixed forms of congenital LVOT obstructive lesions. SVAS may occur sporadically, as a manifestation of elastin arteriopathy, or as part of Williams syndrome (also known as Williams-Beuren syndrome), a genetic disorder with autosomal dominant inheritance.

Anatomy of subtypes

SVAS has 3 commonly recognized morphologic forms. An external hourglass deformity with a corresponding luminal narrowing of the aorta at a level just distal to the coronary artery ostia is present in 50-75% of patients. In approximately 25% of patients, a fibrous diaphragm is present just distal to the coronary artery ostia. In fewer than 25% of patients, a diffuse narrowing along a variable length of ascending aorta is present. Similarly, the following 3 anatomic subtypes of coronary lesions have been recognized in SVAS:

• Circumferential narrowing of the left coronary ostium
• Ostial obstruction due to fusion of the aortic cusp to the supravalvular ridge
• Diffuse narrowing of the left coronary artery

Pathophysiology

The origins of the coronary arteries proximal to the obstruction site have the same systolic pressure as the left ventricle (LV). Consequently, in time they become dilated and tortuous with hypertrophy and intimal thickening, predisposing them to premature atherosclerosis. The hemodynamic consequences of coronary artery changes are manifested by increased total mean coronary flow but significantly decreased diastolic coronary flow, which is the major determinant of the development of myocardial ischemia. Concentric LV hypertrophy caused by SVAS exacerbates the problem of myocardial ischemia. In most patients, the jet of blood flow from SVAS demonstrates preferential trajectory into brachiocephalic vessels, the so-called Coanda effect; this accounts for a marked increase in the right upper extremity systolic pressure relative to the left.

Natural history

Sudden death can occur in untreated patients with SVAS. However, this appears to be relatively rare overall. Sudden death is more common with Williams syndrome and SVAS with diffuse peripheral pulmonary artery stenosis. The natural history of SVAS is progressive in nature and can be more rapid and severe than in congenital aortic valve stenosis. Sudden death, which can occur in persons of all ages, results from severe LVOT obstruction and coronary artery disease. Severe LVOT obstruction and coronary artery disease may also cause progressive dyspnea upon exertion, angina, and syncope in severe cases and may account for the morbidity in SVAS. Bacterial endocarditis can also cause mortality and morbidity in SVAS.

Frequency

United States

The crude incidence of congenital heart defects is 8.8 per 1000 live births, and SVAS accounts for less than 0.05% of these defects. The sporadic form of SVAS is more common than the autosomal dominant form.

International

The international incidence of SVAS is not clearly known.

Mortality/Morbidity

In one series, the actuarial survival rate following operative repair of SVAS was found to be approximately 85% at 15 years.² The mortality rate is higher for the diffuse type of SVAS than the localized type. Aortic valve insufficiency can be present in approximately 25% of patients but is usually nonprogressive after surgical relief of SVAS.

Sex

SVAS has no sex predilection.

Age

Patients with SVAS usually become symptomatic during childhood, but SVAS is usually identified during infancy in cases associated with Williams syndrome. The diagnosis of Williams syndrome can be established molecularly based on genetic analysis; therefore, this diagnosis can be made in utero using chorionic villus tissue. Therefore, particularly in patients with Williams syndrome, SVAS can be detected prenatally if it is revealed with fetal echocardiography.

CLINICAL

Section 3 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Symptoms caused by supravalvar aortic stenosis (SVAS) usually develop in childhood and only rarely do so in infancy; however, some patients may develop symptoms in the second or third decade of life.

• Most pediatric patients present because of a heart murmur or the features of Williams syndrome.
• Dyspnea on exertion, angina, and syncope develop in the course of the disease if untreated.
• • These symptoms indicate at least a moderate degree of LVOT obstruction.
  • Because of the coronary artery involvement, angina may arise early and more often than in other obstructive LVOT lesions.
  • Because of the risk of sudden death in SVAS, the development of angina and syncope should prompt immediate investigation.
• Patients with Williams syndrome may additionally develop systemic hypertension and involvement of joints.

Physical

• Asymmetric upper extremities pulses: Discrepancies between carotid pulsations and upper extremities pulses and blood pressure are the characteristic clinical findings of SVAS. The jet of blood flow from SVAS demonstrates preferential trajectory into brachiocephalic (innominate) artery (ie, Coanda effect), which accounts for the discrepancies.
• Precordium: The precordium is usually hyperdynamic, and the apex of the heart is displaced laterally and inferiorly because of ventricular hypertrophy. A thrill in the suprasternal notch is usually felt because of the trajectory of the blood flow jet from SVAS.
• Heart sounds: The first heart sound is generally normal. A narrowly split, single, or paradoxically split second heart sound and a fourth heart sound are present in severe SVAS.
• Heart murmurs: An ejection click is absent in SVAS. The characteristic systolic murmur of SVAS is crescendo-decrescendo in shape, low pitched, and best heard at the base of the heart sited higher than in valvular aortic stenosis. It radiates mainly to the right carotid artery and tends to peak during the last two thirds of the ventricular systole if the obstruction is severe. A high-pitched, short, early diastolic aortic regurgitation murmur is uncommon in SVAS.

Causes

The precise etiology of SVAS is unknown. Its high association with Williams syndrome, in which an elastin gene mutation is present, suggests that defective connective tissue formation contributes to its pathology.

• SVAS may occur sporadically or as part of Williams syndrome, with autosomal dominant inheritance.
• • Williams syndrome is a genetic disorder caused by a hemizygous deletion or mutation of the elastin gene at band 7q11.
  • Other features of Williams syndrome include elfin facies, mental retardation, outgoing "cocktail party" personality, systemic hypertension, and progressive joint involvement.
  • Other cardiovascular anomalies in Williams syndrome consist of multiple stenoses of peripheral pulmonary arteries, stenosis of origins of carotid, coronary and subclavian arteries, and coarctation of aorta.
  • The familial form of SVAS caused by an autosomal dominant inheritance but without other features of Williams syndrome is a less common presentation.
  • The sporadic form of SVAS is the most common (>50%) presentation. Patients may have associated peripheral pulmonary artery stenosis but show no other features of Williams syndrome.
• The genetic predisposition discussed above is the only known risk factor for acquiring SVAS.

DIFFERENTIALS

Section 4 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

WORKUP

Section 5 of 11  

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• Differentials
• Workup
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• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• No specific laboratory blood tests are required to establish the diagnosis of supravalvar aortic stenosis (SVAS).

Imaging Studies

• Echocardiography: The anatomic diagnosis of SVAS can reliably be made from 2-dimensional echocardiography that uses multiple views, including parasternal, apical long-axis, and suprasternal (see Media file 1).
• • In SVAS with hourglass deformity and diffuse hypoplasia, the diameter of the ascending aorta is smaller than that of the aortic root. In SVAS with fibrous diaphragm, the external ascending aortic diameter is normal, although echogenic membrane is commonly observed above the sinuses of Valsalva.
  • Turbulent color flow mapping indicates the site of hemodynamically significant obstruction and can reveal coronary ostial stenosis, the incidence of which is high in SVAS.
  • Doppler echocardiography can be used to estimate the peak instantaneous pressure gradient across fibrous diaphragm, which correlates well with catheter-measured peak-to-peak gradient, the criterion standard for the assessment of the severity of the stenosis. Thus, the Doppler echocardiography–estimated pressure gradient can reliably be used to discern the severity of the lesion and the need for the intervention. In other forms of SVAS, the peak gradient measured by Doppler echocardiography may not correlate well with the peak-to-peak gradient measured by catheterization.
• MRI: This can provide high definition of the lesion, although obtaining an MRI of infants and young children may require sedation. Alternatively, multislice CT with angiography, which can generate high-resolution images of the lesion within seconds, can be used. However, this process exposes the child to radiation.
• Chest radiography: Cardiac silhouette may be variably increased, and the ascending aorta may be asymmetrically dilated. The presence of both findings indicates hemodynamically significant SVAS.
• Cineangiography: A biplane left ventriculogram and an aortogram can reveal the morphology of supravalvular narrowing, stenosis of the arch vessels, abnormalities of aortic root, and dilated coronary arteries (see Media file 2). Right ventricular or pulmonary arterial angiography should be performed simultaneously to discern the presence of peripheral pulmonary artery stenosis, particularly in Williams syndrome.

Other Tests

• Electrocardiography: Electrocardiography usually reveals left ventricular hypertrophy, depending on the severity of stenosis. ST-T segment changes may be present with involvement of coronary ostia and the coronary arteries.
• Genetic evaluation: Obtain a genetic evaluation for patients with SVAS to discern the diagnosis of Williams syndrome, which is often associated with SVAS. Molecular diagnosis of Williams syndrome can now be made by fluorescent in situ hybridization (FISH) using Williams probe.

Procedures

• A retrograde aortic catheterization with an end-hole catheter can be used to localize the site of obstruction by showing the pressure gradient above the aortic valve on pullback tracing. Cardiac catheterization along with angiography is indicated to evaluate the severity of the lesion and to confirm the coexisting anomalies prior to surgery if they cannot be accurately assessed with other modalities. Blade balloon angioplasty has been effective for associated peripheral pulmonary artery stenosis when conventional balloon angioplasty fails.
• Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.
• Complications include rupture of blood vessel, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.
• Cardiac asystole and mortality due to coronary events have been reported during catheterization and during the postprocedure period. Cardiac catheterization, therefore, should be undertaken only if clearly indicated.

Histologic Findings

Myocardial hypertrophy, coronary intimal hyperplasia, and atherosclerotic changes can be observed in most cases. Subendocardial fibrosis may be present in severe cases of SVAS.

Abnormal deposition of elastin in arterial walls of patients with SVAS has been seen, which leads to the increased proliferation of arterial smooth muscle cells, resulting in the formation of hyperplastic intimal lesions.

TREATMENT

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Medical Care

Surgery is the primary treatment for supravalvar aortic stenosis (SVAS). Catheter intervention in the form of transcatheter balloon angioplasty has not been found to be an effective treatment because the relief in gradient across SVAS is usually small and transient. The restenosis rate is high.

Surgical Care

• Therapeutic intervention is recommended if a combination of clinical features is present or if any one of the investigations provides indication for intervention.
• • Clinical features
  • • Presence of dyspnea on exertion, angina, or syncope
    • Configuration of the systolic murmur with late peaking
  • Echocardiographically measured features
  • • Left ventricular mass-to-volume ratio greater than 2:1
    • Peak instantaneous pressure gradient across SVAS greater than 75 mm Hg
    • Mean pressure gradient greater than 50 mm Hg
  • Catheter-measured features - Peak-to-peak pressure gradient greater than 50 mm Hg
  • Electrocardiographically measured features
  • • Left ventricular hypertrophy with strain
    • ST-segment depression greater than 1 mm at rest or during exercise
• The surgical correction of SVAS is performed using hypothermic cardiopulmonary bypass and cardioplegic arrest. Resection of the supravalvular obstruction and insertion of a fabric patch over the aortotomy is the standard procedure for fibrous diaphragm and hourglass deformity. If patients have diffuse narrowing, the ascending aorta and arch can be reconstructed using an aortic allograft or a pulmonary autograft.
• The operative mortality rate for fibrous diaphragm and hourglass deformity is less than 5%. The operative mortality rate is higher for SVAS with diffuse narrowing than with the other 2 commonly recognized morphologic forms but is reported to be less than 12%.
• Standard postoperative care and precautions for pediatric cardiac patients are also required for patients with SVAS.

Consultations

• Cardiologist
• Cardiothoracic surgeon
• Geneticist

Diet

No special diet is required.

Activity

Recommended physical activities are similar to those for aortic valve stenosis because they are progressive diseases of similar nature.

Patients with coronary artery stenosis or abnormal anatomy should be restricted to participate in physical activities only at a recreational level. Exercise recommendations for children with supravalvular aortic stenosis are as follows:

• Mild degree of stenosis (<20 mm Hg), normal ECG findings, no symptoms - Full sports participation
• Moderate degree of stenosis (21-49 mm Hg), mild left ventricular hypertrophy (LVH), no symptoms - Low static or moderately dynamic sports participation
• Severe degree of stenosis (>50 mm Hg) or moderate degree of stenosis with symptoms - No competitive sports participation (only recreational)

MEDICATION

Section 7 of 11  

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Drug therapy has no role in the treatment of symptomatic patients with supravalvar aortic stenosis (SVAS). Precautions to prevent bacterial endocarditis are necessary. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.¹

FOLLOW-UP

Section 8 of 11  

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Further Inpatient Care

• Follow-up care is recommended for all patients, whether or not they have had surgical correction of supravalvar aortic stenosis (SVAS). Infants and children with SVAS require follow-up at 3- to 6-month intervals; older children require follow-up at 6- to 12-month intervals.
• Rapid progression of SVAS may occur preoperatively.

Further Outpatient Care

• Further outpatient care is required for preoperative evaluation and postoperative follow-up care.

Transfer

• Transfer may be required for further surgical intervention.

Deterrence/Prevention

• Advise patients to avoid strenuous activities and competitive sports (see Activity).

Complications

• Preoperative
• • Progressive coronary osteal stenosis and atherosclerosis
  • Infective endocarditis
  • Sudden death
• Postoperative
• • Aortic insufficiency in 25% of patients
  • Higher mortality rate in patients with diffuse SVS than in those with localized SVAS

Prognosis

• In one series, the actuarial survival rate following operative repair of SVAS was approximately 85% at 15 years. After surgery, most patients remain in class I of the New York Heart Association's (NYHA) functional classification; most do not require reoperation.
• In other large series follow-up (ranging from 6 mo to 30 y, medium 9.4 y), 73% patients were in NYHA functional class I, and 27% were in NYHA functional class II.² Overall survival including operative mortality was 98% at 10 years and 97% at 20 years and at 30 years.
• Prognosis is influenced by the presence of genetic disorders.

Patient Education

• Restrictions
• • Activity: Preoperative recommendations for physical activities should be followed as mentioned in Activity. Physical activity restrictions are not required postoperatively if no residual lesion is present and the pressure gradient is less than 20 mm Hg across the LVOT, which is similar to the preoperative recommendation.
  • Lifestyle implications: In general, persons with SVAS should have risk stratification for coronary artery disease early in adult life because SVAS may predispose the coronary artery to premature atherosclerotic changes.
• Counseling: Council patients and their families regarding the need for long-term follow-up care.

MISCELLANEOUS

Section 9 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to inform patients and their families about exercise restrictions
• Failure to inform patients and their families about antibiotic prophylaxis for bacterial endocarditis
• Failure to recognize development of cardiac ischemia, arrhythmias, or need for intervention

Special Concerns

• Many children with supravalvar aortic stenosis (SVAS) have Williams syndrome, which may be associated with infantile hypercalcemia with some risk of nephrocalcinosis, osteosclerosis with progressive joint limitation and abnormal gait, and neurodevelopmental delay. These children require multidisciplinary support. Use a coordinated management approach. They are also at risk of higher mortality than the normal population because of both cardiac and noncardiac causes.
• Most children are asymptomatic from a cardiovascular standpoint. A timely diagnosis of SVAS may not be made, and patients and their families may comply poorly with follow-up care.
• No published reports have documented the outcome of pregnancy in postoperative patients with SVAS. Address pregnancy on an individual basis, taking into account the type of lesion and surgical procedure performed, the presence of residual lesion, and the associated cardiac and noncardiac conditions and syndromes.

MULTIMEDIA

Section 10 of 11  

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• Miscellaneous
• Multimedia
• References

Media file 1:  Two-dimensional suprasternal echocardiographic image of supravalvular aortic stenosis.
	View Full Size Image
Media type:  Echo

Media file 2:  Aortogram of a patient with supravalvular aortic stenosis and dilated sinus of Valsalva.
	View Full Size Image
Media type:  Radiograph

REFERENCES

Section 11 of 11

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1. Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. J Am Dent Assoc. Jun 2007;138(6):739-45, 747-60. [Medline]. [Full Text].
2. Brown JW, Ruzmetov M, Vijay P, et al. Surgical repair of congenital supravalvular aortic stenosis in children. Eur J Cardiothorac Surg. Jan 2002;21(1):50-6. [Medline].
3. Dridi SM, Foucault Bertaud A, Igondjo Tchen S, et al. Vascular wall remodeling in patients with supravalvular aortic stenosis and Williams Beuren syndrome. J Vasc Res. May-Jun 2005;42(3):190-201. [Medline].
4. Edwards JE. Pathology of left ventricular outflow tract obstruction. Circulation. 1965;31:586-99.
5. Ewart AK, Morris CA, Atkinson D, et al. Hemizygosity at the elastin locus in a developmental disorder, Williams syndrome. Nat Genet. Sep 1993;5(1):11-6. [Medline].
6. French JW, Guntheroth WG. An explanation of asymmetric upper extremity blood pressures in supravalvular aortic stenosis: the Coanda effect. Circulation. Jul 1970;42(1):31-6. [Medline].
7. Gersony WM, Hayes CJ, Driscoll DJ, et al. Bacterial endocarditis in patients with aortic stenosis, pulmonary stenosis, or ventricular septal defect. Circulation. Feb 1993;87(2 Suppl):I121-6. [Medline].
8. Jureidini SB, Marino CJ, Singh GK, et al. Main coronary artery and coronary ostial stenosis in children: detection by transthoracic color flow and pulsed Doppler echocardiography. J Am Soc Echocardiogr. Apr 2000;13(4):255-63. [Medline].
9. Keane JF, Fellows KE, LaFarge CG, et al. The surgical management of discrete and diffuse supravalvar aortic stenosis. Circulation. Jul 1976;54(1):112-7. [Medline].
10. Kirklin JW, Barratt-Boyes BG. Congenital aortic stenosis. In: Cardiac Surgery. Vol 2. 2^nd ed. New York, NY: Churchill Livingstone Inc; 1993:1195-1238.
11. Latson LA. Aortic stenosis: Valvular, supravalvular, fibromuscular subvalvular. In: Garson A, Bricker JT, McNamara DG, eds. The Science and Practice of Pediatric Cardiology. Philadelphia, Pa: Lea & Febiger; 1990:1334-52.
12. Peterson TA, Todd DB, Edwards JE. Supravalvular aortic stenosis. J Thorac Cardiovasc Surg. Nov 1965;50(5):734-41. [Medline].
13. Rodriguez-Revenga L, Badenas C, Carrio A, Mila M. Elastin mutation screening in a group of patients affected by vascular abnormalities. Pediatr Cardiol. Nov-Dec 2005;26(6):827-31. [Medline].
14. Sugiyama H, Veldtman GR, Norgard G, et al. Bladed balloon angioplasty for peripheral pulmonary artery stenosis. Catheter Cardiovasc Interv. May 2004;62(1):71-7. [Medline].
15. Tani LY, Minich LL, Pagotto LT, Shaddy RE. Usefulness of doppler echocardiography to determine the timing of surgery for supravalvar aortic stenosis. Am J Cardiol. Jul 1 2000;86(1):114-6. [Medline].
16. Wren C, Oslizlok P, Bull C. Natural history of supravalvular aortic stenosis and pulmonary artery stenosis. J Am Coll Cardiol. Jun 1990;15(7):1625-30. [Medline].

Article Last Updated: Nov 19, 2007