Basics
Description
- Congenital aortic stenosis is characterized by narrowing of the aortic valve orifice, leading to LV hypertrophy, and, in the most severe form, myocardial dysfunction.
- Pathologic abnormalities described include asymmetric malformation of the valve leaflets leading to a unicuspid or bicuspid valve, or, more rarely, fusion of normal tricuspid leaflets.
- The valve leaflets are often thickened due to the turbulence of flow across the area, which may lead to calcification in later life.
Epidemiology
- Aortic valve stenosis is more common among boys. Male > Female, 4:1.
- Aortic stenosis has two modes of presentation:
- The majority of patients present in infancy or early childhood with an asymptomatic heart murmur.
- Neonates with critical aortic stenosis present with severe CHF shortly after birth secondary to severe obstruction and LV dysfunction.
Incidence
2-4 per 10,000 live births
Prevalence
3-6% of all children with congenital heart disease
Risk Factors
Genetics
Aortic stenosis is rarely associated with a chromosomal syndrome:
- Valvar aortic stenosis has been described in 18% of patients with Turner syndrome (XO).
- In patients with multiple congenital anomalies, rare reports of associated chromosomal deletions have been described.
- A higher incidence of bicuspid aortic valve and other LV outflow tract abnormalities is found in relatives of patients with congenital aortic stenosis.
Pathophysiology
- Aortic stenosis causes obstruction of blood flow from the LV to the aorta. LV hypertrophy occurs in response to the increased afterload on the LV.
- Systolic LV dysfunction occurs more commonly in the neonate with severe obstruction and hypertrophy and rarely in the older child.
- Diastolic dysfunction may occur with severe LV hypertrophy and systolic dysfunction, most commonly in the neonate.
- In critical aortic stenosis of the neonate, the patent ductus arteriosus augments cardiac output via flow from the RV to the aorta.
Etiology
Congenital
Associated Conditions
Associated cardiac anomalies occur in ~20% of cases. The most common associations are with other left-sided obstructive lesions such as coarctation of the aorta, supravalvar aortic stenosis, subaortic stenosis, mitral valve abnormalities, and other complex lesions such as single ventricle. It is rarely associated with other congenital heart defects.
The increased cardiac output and decreased peripheral vascular resistance that occur during pregnancy are risk factors for adverse outcomes in women with significant aortic stenosis.
Diagnosis
- Aortic stenosis in the older child:
- Significant disease can be present in the absence of symptoms and, in general, symptoms are a late manifestation.
- Symptoms are related to decreased cardiac output and/or myocardial ischemia and are present only with severe obstruction.
- Critical aortic stenosis of the neonate:
- Symptoms are related to LV dysfunction. A right-to-left shunt via the patent ductus arteriosus required to augment cardiac output causes cyanosis.
History
- Aortic stenosis in the older child:
- Exercise intolerance, exertional dyspnea, angina, syncope, palpitations.
- Critical aortic stenosis in the neonate:
- Tachypnea, tachycardia, cyanosis, poor feeding.
Physical Exam
- Cardiac exam:
- Murmur at the base of the heart, radiating to the jugular notch, carotid vessels, and apex.
- Suprasternal notch thrill, even in mild aortic stenosis.
- Systolic ejection click at the cardiac apex.
- LV heave and a thrill at the base of the heart are felt in moderate to severe stenosis:
- Physical findings obscured in neonate with severe stenosis.
- Heart failure exam:
- Failure to thrive
- Tachypnea
- Retractions
- Cyanosis
- Hepatomegaly
- Decreased peripheral perfusion
Tests
EKG abnormalities including LV hypertrophy, LV strain, and ischemic changes with exercise are an indication of the severity of the obstruction, but occasionally severe stenosis may be associated with a relatively benign EKG.
Lab
In the neonate with critical aortic stenosis, evaluation of acid/base status, serum lactate, renal and hepatic function should be performed to assess the adequacy of cardiac output.
Imaging
Echo:
- Optimal method of evaluating aortic valve anatomy. 3D imaging may be useful to delineate the valve anatomy.
- The instantaneous gradient across the valve can be estimated from the velocity of blood flow measured by continuous-wave Doppler, but overestimation is not unusual. The mean gradient may be more representative of the systolic gradient measured at catheterization.
- LV hypertrophy and function can be quantitatively assessed.
- Aortic insufficiency can be documented by color Doppler imaging.
- Associated cardiac defects can be identified.
Surgery
Cardiac catheterization is not indicated to establish the diagnosis and severity of aortic stenosis in the majority of patients.
Pathological Findings
Thickened, dysplastic valve leaflets with fusion of one or more of the valve cusps to form functionally bicuspid or unicuspid valve.
Differential Diagnosis
The differential diagnosis of the asymptomatic child with a murmur of LV outflow tract obstruction includes subaortic stenosis, valvar aortic stenosis, supravalvar aortic stenosis, and hypertrophic cardiomyopathy with LV outflow obstruction.
Treatment
Medication
- Medical therapy is not indicated in the asymptomatic patient with aortic stenosis.
- In neonates with critical aortic stenosis, aggressive medical therapy is required to stabilize the patient and improve ventricular function, including mechanical ventilation, correction of acidosis, and inotropic support. Prostaglandin E1 may be used to maintain ductal patency and augment systemic output via the RV prior to intervention. Relief of obstruction is required on an urgent basis.
Additional Treatment
General Measures
Antibiotic prophylaxis against bacterial endocarditis is not indicated according to the recommendations of the American Heart Association.
Additional Therapies
- Indications for intervention:
- Critical aortic stenosis in the neonate.
- Older children: Continuous wave Doppler peak instantaneous gradient across the aortic valve of >70 mm Hg usually in conjunction with at least moderate LV hypertrophy by echocardiography or ECG, and consistent physical findings.
- Balloon valvuloplasty may be indicated in older children with a peak to peak systolic gradient <60 mm Hg or median gradient <50 mm Hg who have significant ventricular hypertrophy, or evidence of ventricular dysfunction.
- Balloon valvuloplasty:
- Procedure of choice for relief of moderate to severe aortic stenosis in infants and children
- Balloon valvuloplasty may be complicated by aortic insufficiency, femoral arterial injury, or thromboembolic events.
- Aortic valve replacement may be required following balloon valvuloplasty if severe aortic insufficiency occurs or the relief of the aortic valve gradient is inadequate following the valvuloplasty.
- In patients who develop restenosis of the aortic valve following valvuloplasty, repeat valvuloplasty can be attempted unless significant aortic insufficiency is present.
Surgery
- Surgical valvotomy:
- May be performed as a primary procedure in the neonate with critical aortic stenosis and severely compromised ventricular function.
- Valvuloplasty has been increasingly successful in many centers for all age groups.
- Direct visualization of the aortic valve at surgery also may be necessary to relieve stenosis in certain anatomic subtypes that are unresponsive to balloon valvuloplasty, eg, calcific aortic stenosis or univentricular valves with annular hypoplasia.
- Aortic valve replacement:
- Can be performed using a prosthetic mechanical valve, a bioprosthesis, such as an aortic allograft, bovine, or porcine valve, or a pulmonary autograft (the Ross procedure)
- Ross procedure:
- Procedure of choice at many centers for aortic valve replacement in infants and young children
- The native aortic and pulmonary valves are excised and the pulmonary valve is implanted into the aortic root.
- A pulmonary or aortic homograft is used to connect the RV to the main pulmonary artery.
- The use of the native pulmonary valve to replace the stenotic aortic valve avoids the need for chronic anticoagulation and affords the potential for normal growth.
- The incidence of restenosis of the neoaortic valve is low, although in some cases valve replacement has been necessary because of significant neoaortic insufficiency.
- Replacement of the RV to pulmonary artery homograft may be necessary within 10 yr because of stenosis of the homograft.
- Mechanical valve replacement:
- In the older adolescent patients, mechanical valves, such as the St. Jude's prosthetic valve, offer excellent relief of stenosis for up to 15-20 yr. Replacement may be necessary for recurrent stenosis or paravalvar leak.
- In infants and small children, mechanical valve use is limited by the lack of growth, which necessitates earlier valve replacement.
- Chronic anticoagulation is necessary to prevent complications of thromboembolism.
- Bioprosthetic valve:
- Aortic valve replacement with a bioprosthetic valve is gaining adherents as improved valve longevity has evolved.
- A bioprosthetic valve is used in patients in whom chronic anticoagulation may be contraindicated, such as young women of child-bearing age.
In-Patient Considerations
Admission Criteria
- Signs and symptoms of heart failure
- Monitoring postcatheterization or post surgical intervention
Discharge Criteria
- Relief of obstruction
- Resolution of heart failure symptoms
- Recovery from surgical intervention
Ongoing Care
Follow-Up Recommendations
- Aortic stenosis is a progressive disease that requires close monitoring for signs of increasing obstruction and LV hypertrophy.
- Once intervention has been performed, follow-up is necessary to:
- Assess the degree of residual aortic valve stenosis and insufficiency.
- Monitor anticoagulation therapy following artificial valve placement.
Patient Education
Activity:
- Recommendations for participation in recreational and competitive sports are guided by the echocardiographically estimated valve gradient, the degree of LV hypertrophy, and clinical status.
- See Appendix table Activity Recommendations.
Prognosis
- Aortic stenosis in the older child:
- Although balloon valvuloplasty and surgical valvotomy result in significant relief of obstruction in 80-90% of patients, valvar aortic stenosis is a progressive disease, with 50% of patients requiring further intervention within 10 yr after initial therapy.
- Critical aortic stenosis in the neonate:
- The mortality rate in newborns with critical aortic stenosis is 12-30%, due to the presence of significant LV systolic and diastolic dysfunction.
- Restenosis is common after surgical or catheter relief of obstruction in the neonatal period, with 20% of survivors requiring further intervention within 5 yr of their initial procedure.
- Long-term survival and quality of life has improved markedly in recent years.
Complications
- LV systolic and diastolic dysfunction if ventricular hypertrophy is long-standing
- Aortic insufficiency following valvuloplasty or valvotomy
- RV outflow tract obstruction following the replacement of the pulmonary valve in the Ross procedure
- Complications of anticoagulation therapy following artificial valve replacement
Additional Reading
1Block PC, Bonhoeffer P. Percutaneous approaches to valvular heart disease. Curr Cardiol Rep. 2005;7(2):108-113. [View Abstract]2Fratz S, Gildein HP, Balling G. Aortic valvuloplasty in pediatric patients substantially postpones the need for aortic valve surgery: a single-center experience of 188 patients after up to 17.5 years of follow-up. Circulation. 2008;117(9):1201-1206. [View Abstract]3Ross DN. Replacement of aortic and mitral valves with a pulmonary autograft. Lancet. 1967;2(7523):956-958. [View Abstract]4Siu SC, Colman JM. Heart disease and pregnancy. Heart. 2001;85(6):710-715. [View Abstract]5Tzemos N, Silversides CK, Colman JM. Late cardiac outcomes after pregnancy in women with congenital aortic stenosis. Am Heart J. 2009;157(3):474-480. [View Abstract]6Williams IA, Quaegebeur JM, Hsu DT. Ross procedure in infants and toddlers followed into childhood. Circulation. 2005;112(9 Suppl):I390-1339. [View Abstract]
Codes
ICD9
746.3 Congenital stenosis of aortic valve
SNOMED
18546004 congenital stenosis of aortic valve (disorder)