Version May 2024
INTRODUCTION — Left ventricular outflow tract (LVOT) obstructive lesions account for approximately 6 percent of cases of congenital heart disease in children; in one series, the incidence was estimated to be 3.8 in 10,000 live births [1,2]. Obstruction can occur at valvar, subvalvar, and supravalvar levels.
The most common form of LVOT obstruction in children is valvar aortic stenosis (AS), accounting for as many as 71 to 86 percent of patients [2-4]. More than three-quarters of affected patients are male [3].
Valvar AS will be reviewed here. Subvalvar and supravalvar AS are discussed separately. (See "Subvalvar aortic stenosis (subaortic stenosis)".)
ETIOLOGY — Among children with valvar aortic stenosis (AS), the most common cause is a bicommissural or bicuspid aortic valve, that is, only two leaflets are present rather than the normal three. Bicommissural aortic valve is associated with both congenital and acquired AS. It is also the most common cause of acquired AS in adults. As an example, a review of 932 adults who underwent operative excision of an AS valve reported that two-thirds of the patients had a bicommissural aortic valve [5]. The severity of AS progressed with age, with the majority of patients requiring surgical intervention after 50 years of age. (See "Clinical manifestations and diagnosis of bicuspid aortic valve in adults".)
Based upon large retrospective autopsy studies, bicommissural aortic valve had been estimated to occur in 1 to 2 percent of the general population [5-8]. This is likely to be an overestimation, as demonstrated by two echocardiographic screening studies which reported a lower prevalence of 0.5 percent in both neonates [9] and school-aged children [10]. In each of these studies, bicommissural aortic valves were more common among males than females (0.7 versus 0.2 percent) [9,10]. Familial clustering has also been observed, as approximately 35 percent of patients with a bicommissural aortic valve have at least one additional family member with a bicommissural aortic valve [11].
Patients with congenital AS are slightly more likely to have offspring with congenital heart disease (CHD). This was illustrated in a report from the Second Natural History Study of Congenital Heart Defects (NHS-2) in which CHD occurred in 3 offspring of 251 (1.2 percent) males with AS and 1 of 72 females (1.4 percent) [12]; these values are somewhat higher than the 0.5 to 0.8 percent incidence of CHD in live births in the general population [1,13].
Associated cardiovascular anomalies have been noted in as many as 20 percent of children with congenital AS [14]. Among patients with a bicommissural aortic valve, coexisting coarctation of the aorta is seen in approximately 6 percent of cases [8]; on the other hand, as many as 30 to 40 percent of patients with coarctation have a bicommissural aortic valve [15]. Dilated ascending aorta is commonly associated with bicommissural aortic valve. Less common concomitant congenital anomalies include ventricular septal defect, patent ductus arteriosus, bicommissural pulmonic valve, and congenital mitral regurgitation. (See "Clinical manifestations and diagnosis of bicuspid aortic valve in adults" and "Clinical manifestations and diagnosis of coarctation of the aorta".)
Less common forms of congenital AS include:
●Unicommissural or unicuspid aortic valves, in which two of the three commissures are fused [16,17].
●Aortic annular hypoplasia, which may be an isolated abnormality or may be seen in association with leaflet abnormalities [18,19].
These rarer forms of congenital AS are often associated with severe obstruction to left ventricular outflow and heart failure in infancy.
ANATOMY — The normal aortic valve has three commissures, which results in three leaflets of approximately equal size [20]. The free margins of the leaflets have a semilunar shape. Normal leaflets are smooth and pliable. In older patients, a fibrous nodule may be located at the center of their free margins.
Mild aortic stenosis (AS) from a bicommissural aortic valve commonly progresses as the patient ages, although the rate is variable [21]. In the majority of patients with bicommissural aortic valves, the size of the valve leaflets is unequal, which is thought to result from the fusion or absence of one of the three valve commissures; a false commissure or raphe is frequently present [8]. With absence of the right-left (intercoronary) commissure, the most common form, the leaflets are oriented anterior and posterior, the raphe is usually in the anterior leaflet, and both coronary arteries arise from the aortic sinuses above the anterior leaflet. In a series of 1135 patients, this orientation was found in 70 percent of cases [22].
Less commonly, there is absence of the right-noncoronary commissure, and the leaflets are oriented to the right and left; the raphe is usually in the right leaflet, and the coronary arteries arise from the aortic sinuses above each leaflet (movie 1) [20]. Absence or fusion of the left-noncoronary commissure is exceedingly rare. The free margins of a bicommissural valve are relatively straight rather than semilunar. This configuration limits their mobility [20].
Bicommissural valve morphology has clinical and prognostic importance, as illustrated in the review of 1135 patients cited above [22]. Patients with fusion of the right-noncoronary commissure had a higher incidence of valvar dysfunction: moderate or greater AS, and moderate or greater aortic regurgitation (AR). In contrast, patients with the more common absence of the right-left commissure had lesser degrees of aortic valve dysfunction but an increased incidence of coarctation of the aorta; 89 percent of patients with coarctation and a bicommissural aortic valve had the absent right-left commissure morphology.
In a subsequent nested cohort longitudinal study of 310 patients selected from the above study [22], patients with the right-noncoronary commissural absence compared with those with right-left commissural absence were more likely to require intervention because of more rapid progression of AS and AR [23].
A unicommissural or unicuspid aortic valve results from the absence of two of the three commissures. Most commonly, the patent commissure is the left-noncoronary commissure, which results in a valve with an eccentric, teardrop-shaped opening that may extend leftward and posteriorly to the annulus. The valve is thus described as having a single "cusp." Absence of all three commissures results in aortic atresia and usually in the hypoplastic left heart syndrome.
PHYSIOLOGY — In most cases of valvar aortic stenosis (AS), systemic blood pressure and cardiac output remain normal because left ventricular (LV) systolic pressure and total cardiac work are elevated. Despite the increase in total cardiac work, wall stress remains normal or even reduced, presumably because of the compensatory increase in LV wall thickness. In a study of LV mechanics, the ejection fraction (0.88 versus 0.64) and mean velocity of fiber shortening (1.8 versus 1.22 circ/s) were higher in children with AS than in normal subjects [24].
An important physiologic derangement in valvar AS is the relative reduction in coronary blood supply to a hypertrophied, hypertensive LV with increased myocardial oxygen demand. This may lead to subendocardial ischemia and infarction. The imbalance between supply and demand is due to a decrease in coronary perfusion pressure and a shortened diastolic filling period (due to prolonged systolic ejection across the stenotic orifice). This imbalance is exaggerated by exercise, which further shortens the diastolic filling period, decreases coronary perfusion, increases the gradient across the stenotic aortic valve, and results in both increased myocardial oxygen demand and decreased myocardial oxygen delivery [25].
CLINICAL FEATURES — Most children with congenital valvar aortic stenosis (AS), even to moderate degrees, are relatively asymptomatic [26]. Patients with bicommissural valves and no stenosis still require long-term follow-up because progressive stenosis develops in approximately 75 percent of adults. Thickening and focal calcification of the bicommissural valve can be detected pathologically and on echocardiography as early as the second decade of life [27].
More severe disease in childhood is not uncommon, as approximately 10 percent of patients develop heart failure during the first year after birth. Of these, approximately two-thirds become symptomatic by two months of age, and most present before six months. Infants with critical AS, the most severe form, present with signs of severe heart failure or cardiogenic shock in the neonatal period or shortly thereafter, following closure of the ductus arteriosus.
Critical aortic stenosis — Critical AS is often well tolerated in utero because left ventricular (LV) output is decreased and the right ventricle (RV) supports a greater share of the fetal cardiac output via the ductus arteriosus. However, there are reports of in utero cardiac dysfunction, hydrops fetalis, and endocardial fibroelastosis due to critical AS [28,29]. In particular, the rare combination of severe fetal AS and mitral regurgitation results in left heart dilation and compression of the RV, causing poor cardiac output and hydrops fetalis, and a poor outcome [30].
In addition, severely restricted forward flow from critical AS may lead to hypoplastic left heart syndrome (HLHS) with small left-sided heart structures in utero [31]. Fetal echocardiography may be helpful in predicting which fetuses with AS will develop HLHS. Identification of these fetuses becomes increasingly important with the possible development of in utero intervention to prevent the progression of AS to HLHS. In one study from a tertiary center, fetuses at midgestation (16 to 30 weeks gestation) who were more likely to develop HLHS had echographic findings of reversed blood flow in the transverse aortic arch, left-to-right blood flow across the foramen ovale, monophasic mitral valve inflow, and moderate to severe LV dysfunction [32]. However, the ability to detect these changes is dependent on operator expertise, and in other clinical settings the ability to detect prenatal heart disease is low [13]. (See 'Fetal intervention' below and "Hypoplastic left heart syndrome: Management and outcome", section on 'Fetal intervention' and "Congenital heart disease: Prenatal screening, diagnosis, and management".)
Following delivery, the ductus arteriosus closes, pulmonary vascular resistance falls, and venous return to the left atrium increases. If the LV cannot fill or eject a sufficient volume of blood, cardiac output cannot be maintained, leading to signs and symptoms of heart failure or even cardiogenic shock [33]. This condition is fatal without intervention.
Infants with critical AS may present at birth with poor peripheral perfusion and cyanosis. Physical examination reveals a hyperactive precordium and poor pulses. A cardiac murmur is frequently not heard because of the poor cardiac output. Although a gallop rhythm may be appreciated, an ejection click is almost never present. Distal pulses are often poor or inappreciable.
Infantile aortic stenosis — Infants with severe, but not critical, AS present in infancy with heart failure. They typically have tachypnea, poor feeding, and growth failure. (See "Heart failure in children: Etiology, clinical manifestations, and diagnosis", section on 'Clinical manifestations'.)
A hyperactive precordium is usually present on physical examination. Most have a characteristic ejection murmur along the upper left sternal border that radiates to the neck, although it may be very soft if heart failure is severe. An ejection click may be heard. Many patients have hepatomegaly and peripheral edema.
Older children — Older children with AS are rarely symptomatic. Nearly all have appropriate growth and development [26,34]. Some patients report fatigability, which appears to be unrelated to the severity of AS. Angina and syncope occur in less than 5 percent of children with valvar AS and are more common in those with higher gradients [26].
Older children typically have normal vital signs, including blood pressure. Auscultation and palpation may reveal one or more of the following (table 1) [20]:
●Visible apical activity and an increased LV impulse on palpation are common with severe stenosis.
●The first heart sound is usually normal, and the second heart sound is normally split unless stenosis is severe.
●Approximately 60 to 90 percent of children with valvar AS have an ejection click, which is usually loudest at the apex or lower left sternal border (movie 2).
●A systolic ejection murmur is present; its intensity is proportional to the extent of stenosis. The murmur typically has a harsh, loud, crescendo-decrescendo quality (movie 3).
●Approximately one-third of patients also have a diastolic regurgitant murmur [26]. (See "Aortic regurgitation in children".)
As the severity of stenosis increases, the following auscultatory changes occur (see "Auscultation of cardiac murmurs in adults"):
●The ejection click may disappear.
●The ejection murmur becomes harsh, longer, and peaks later with increasing obstruction. The late peak is associated with a delay in the carotid upstroke.
●The intensity of the aortic component of the second sound decreases, and paradoxical splitting of the second sound may occur.
●A systolic thrill may be palpable at the right base or suprasternal notch.
CLINICAL COURSE — Patients with congenital valvar aortic stenosis (AS) often have progressive obstruction over time [35,36]. In addition, they are at risk for infectious endocarditis and sudden death [35,37].
The long-term outcome of this disorder was evaluated in the Second Natural History Study of Congenital Heart Defects (NHS-2) study, which included 371 patients (mostly children) with AS who underwent cardiac catheterization from 1958 to 1969; 92 percent were asymptomatic [35]. Most patients with gradients across the aortic valve ≥80 mmHg underwent valvotomy, whereas those with gradients <50 mmHg were mostly treated medically. Patients with intermediate gradients had either medical or surgical therapy. The following findings were noted:
●The probability of 25-year survival was 92.4 and 81 percent for patients with initial peak systolic ejection gradients <50 or ≥50 mmHg, respectively.
●In 32 percent of 212 patients who were treated medically, obstruction progressed to a severe gradient, especially in the younger patients.
●The likelihood of needing surgery in 25 years was 20, 40, and 60 percent for patients with initial gradients of <25, 25 to 49, and 50 to 79 mmHg, respectively.
●Sudden death occurred in 25 patients (5 percent) and accounted for more than one-half of cardiac deaths. These patients were almost all older than 10 years and had significant obstruction and/or aortic regurgitation; 19 had prior surgery.
●Infectious endocarditis occurred in 3 percent. In another report from this registry, the overall risk of endocarditis was 0.27 percent per year [37]. The risk was greater in patients treated surgically (0.41 versus 0.16 percent per year in those with less severe disease who were treated medically). The applicability of these findings to current practice is uncertain since the data were obtained before widespread use of antimicrobial prophylaxis. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)
A study of patients with mild AS (initial systolic gradient between 10 and 25 mmHg) reported that a low gradient-slope of <1.2 mmHg/year (change of gradient over time in years) was associated with a low risk of increasing obstruction and need for surgical correction [38]. Based upon their results, the authors suggested that follow-up echocardiography could be performed every four to five years in this low-risk group, but in children with higher gradient-slope (≥1.2 mmHg/year), echocardiography should be performed every one to two years.
A similar finding of a slow progression of obstruction in children with mild disease was reported in a retrospective study of 245 children with valvar AS followed over a mean of nine years (range 0.1 to 19.4 years) [39]. The rates of intervention and mortality were greatest in patients diagnosed in infancy with more severe disease. Deaths in infants were mostly due to progressive left ventricular dysfunction.
DIAGNOSIS — The diagnosis of valvar aortic stenosis (AS) is almost always made by physical examination and echocardiography. Cardiac catheterization is performed if the diagnosis remains uncertain, if there are associated defects that cannot be completely evaluated noninvasively, or if balloon aortic valvuloplasty (BAV) is anticipated.
Echocardiography — The diagnosis is confirmed by two-dimensional echocardiography with Doppler analysis. This technique is used to estimate the severity of obstruction and evaluate left ventricular (LV) function, valve morphology, and the degree of aortic regurgitation. (See "Echocardiographic evaluation of the aortic valve".)
M-mode and two-dimensional echocardiography are useful for demonstrating reduced valve leaflet mobility and making measurements of valve orifice area, as well as documenting the presence of poststenotic dilation of the supravalvar aortic root (movie 1 and movie 4).
Using Doppler echocardiography and Bernoulli equation, the maximum instantaneous gradient across the stenotic valve can be estimated [40]. This value is usually higher than the phase shifted peak-to-peak gradient between the LV and aorta measured at catheterization. Mean gradient values estimated by Doppler correlate better with those measured at catheterization [41]. (See "Aortic valve area in aortic stenosis in adults".)
Electrocardiogram — The electrocardiogram (ECG) is of limited use in children with AS. It is typically abnormal in infants with critical AS, although rarely diagnostic. The majority of older infants have evidence of LV hypertrophy and inverted T waves, although these findings may be absent and cannot be used to estimate the extent of severity [20].
The ECG also has limited utility in distinguishing mild from severe obstruction in older affected children (more than two years of age) because of the lack of a close correlation between the ECG and the transvalvar pressure gradient [26,35]. In children with less severe initial disease, the ECG is often normal until the later stages. On the other hand, evidence of LV hypertrophy, with or without repolarization abnormality, has been described in approximately 30 percent of children with a significant degree of stenosis [35].
Chest radiograph — Chest radiographs in symptomatic infants typically show cardiomegaly that may be severe. In general, cardiac enlargement in older patients does not correlate with the severity of stenosis [20]. Dilation of the ascending aorta may be seen in older patients.
Exercise testing — Exercise testing is not usually performed in children. In adults with AS, the ST segment change during exercise correlates with the echocardiographic Doppler maximum transaortic gradient [42]. However, in children and young adults, the false-positive rate (ST changes with less severe stenosis) for exercise testing may be as high as 40 percent [43].
Cardiac catheterization — Cardiac catheterization is performed if the diagnosis remains uncertain, if there are associated defects that cannot be completely evaluated by echocardiography, or if BAV is anticipated. Catheterization provides both hemodynamic and anatomic data, such as the gradient across the valve, ventricular end-diastolic pressure, cardiac output, and anatomy and competency of the valve. Associated lesions, such as aortic coarctation, can also be defined. (See "Hemodynamics of valvular disorders as measured by cardiac catheterization", section on 'Aortic stenosis'.)
As part of this procedure, balloon valvotomy can be performed if indicated. (See 'First-line treatment' below.)
TREATMENT
Fetal intervention — Fetal intervention has the potential to change the course of severe and possibly fatal cardiac lesions. Fetal balloon valvuloplasty may reverse the development of hypoplastic left heart syndrome in patients with critical aortic stenosis (AS). In these fetuses, balloon valvuloplasty may increase forward flow to the left ventricle (LV), allowing its continued growth. (See "Hypoplastic left heart syndrome: Management and outcome", section on 'Fetal intervention'.)
Postnatal intervention — Definitive therapy consists of reducing the degree of valvar stenosis. The treatment of choice is balloon valvuloplasty, which has largely replaced surgery. Surgical options include valvotomy and valve replacement, which is now rarely performed for valvar AS in children. However, patients who develop severe aortic regurgitation (AR) following balloon dilation require surgical treatment. In such patients, valve repair is effective and usually preferred to valve replacement. (See "Aortic regurgitation in children".)
Indications for intervention — Specific treatment for AS depends upon the degree of obstruction and is independent of the age of the patient. Those with severe obstruction require intervention, which is especially urgent in the critically ill newborn. Transitional support of the systemic circulation can be achieved by intravenous administration of prostaglandin E1 (also known as alprostadil) to open or maintain the patency of the ductus arteriosus, which allows the right ventricle (RV) to support the systemic circulation.
Data from the 371 patients with congenital aortic stenosis included in the Second Natural History Study of Congenital Heart Defects (NHS-2) study provide some guidance for therapy [35]. All gradients in this study were measured at cardiac catheterization.
●Patients with a peak-to-peak systolic gradient of 25 mmHg or less at catheterization or on echocardiogram have a low mortality and a low overall risk of requiring surgery (20 percent) over a 25-year period. These patients can be followed medically with annual evaluation. A follow-up study of this cohort with very mild stenosis demonstrated that the slope of the transaortic gradient (change of gradient/time [years]) was predictive of outcome, so that those with gradient slope >1.2 merited annual follow-up, and those with slope <1.1 could be followed somewhat less frequently [38].
●Those with peak-to-peak systolic gradients greater than 50 mmHg are at high risk for ventricular arrhythmias and sudden death, and have a 71 percent likelihood of requiring intervention. It seems prudent, therefore, to proceed with intervention immediately in these patients, whether or not they have symptoms.
A more difficult decision is faced with the patient whose peak-to-peak gradient is between 25 and 50 mmHg. These patients are at intermediate risk for both sudden death and the long-term likelihood of requiring surgery. Given the morbidity and mortality of intervention, however small, it has been suggested these patients be treated medically and followed closely for a worsening gradient or the development of symptoms [35].
First-line treatment — Percutaneous balloon aortic valvotomy (or valvuloplasty, BAV) is the therapy of choice for valvar AS in children in most tertiary centers, including our own. The aortic valve leaflets in children are typically pliable and usually easy to dilate and/or tear. This is in contrast to adult patients with AS, in whom calcific changes in the valve make them less amenable to effective dilation. (See "Indications for valve replacement for high gradient aortic stenosis in adults", section on 'Symptomatic patients'.)
BAV results in a 50 percent reduction in gradients in the majority of patients [44-49]. Most patients develop new or increased AR, which is moderate to severe in approximately 15 percent immediately after the procedure and can progress over time. (See 'Aortic regurgitation' below and "Aortic regurgitation in children".)
Outcomes following BAV vary somewhat according to age:
●Neonates – Data on the specific outcomes of BAV in neonates are from retrospective reviews from single tertiary centers.
In one study, the clinical outcome was evaluated in 113 infants who underwent BAV at ≤60 days of age from 1985 to 2002 [48]. Early mortality fell from 22 percent between 1985 and 1993 to 4 percent between 1994 and 2002. The relative gradient reduction following BAV was 54 percent, and clinically significant AR developed in 15 percent. Patients with initially small left heart structures (aortic annulus, LV end-diastolic dimension) normalized within one to two years. Among 91 early survivors with a biventricular circulation, the five-year rates of freedom from moderate to severe AR, reintervention for residual or recurrent AS or for AR, and valve replacement were 65 percent, 48 percent, and 84 percent, respectively. Most reinterventions occurred in the first year.
In another study, 53 neonates who underwent BAV at ≤30 days (median age 3.5 days) of age from 1994 to 2004 were evaluated [50]. During a median follow-up of 3.2 years, there were seven deaths (21 percent). The presence of moderate or severe LV endocardial fibroelastosis was associated with an increased risk of death. During the follow-up period, there were 31 reinterventions. Patients with a small aortic annulus were at an increased risk for aortic valve replacement (AVR). There was catch-up growth of the left-sided heart structures with increases in the aortic valve annulus, aortic sinus, and LV dimensions as previously reported [48], but the size of the mitral valve remained below the normal range for body surface area.
Aortic wall injury is a procedure-related complication noted in some neonates undergoing BAV, with little demonstrable associated mortality [51].
●Children and adolescents – The long-term outcome of BAV was evaluated in 509 children and adolescents with congenital AS (the majority of whom had isolated native AS) who underwent the procedure at a median age of 2.4 years (age range from 1 day to 40.5 years) from 1985 to 2008 at Boston Children's Hospital with median follow-up of 9.3 years [52]. Survival at 5, 10, and 20 years was 95, 93, and 88 percent, respectively. Peak AS gradients decreased significantly after dilation, with a median decrease of 35 mmHg. Moderate to severe AR was present in 14 percent of patients following BAV. Patients >11 years old were more likely to have AR than younger patients. Repeat interventions were performed in 44 percent of patients (n = 225), including repeat BAV in 115 patients (23 percent), aortic valve repair in 65 (13 percent), and AVR in 116 (23 percent). Survival rates free from any aortic valve intervention were 89, 72, 65, and 27 percent at 1, 5, 10, and 20 years, respectively. In multivariate analysis, a longer time period prior to AVR was associated with lower postdilation AS gradient and lower grade of postdilation AR, but not age, predilation AS severity, or the year BAV was performed.
Similar findings were noted in a case series of 272 patients (age range 1 day to 30.5 years) who underwent BAV from 1985 to 2009 at Texas Children's Hospital [53]. Survival without transplantation was 89, 87, and 81 percent at 10, 15, and 20 years after initial BAV, respectively, at an average follow-up of 5.8 years. Death (n = 22) and transplantation (n = 2) occurred at a median time of 0.44 years after BAV. Other outcomes included AVR in 15 percent of patients, repeat BAV in 15 percent of patients, and the presence of moderate or severe AR in 31 percent of patients.
In an older multicenter case series of 630 BAVs in 606 children and adolescents (median age 6.8 years) from the Valvuloplasty and Angioplasty of Congenital Anomalies Registry, BAV was successful in 83 percent of procedures, and the LV to aortic gradient was reduced by a mean of 60 mmHg [46].
Recurrent obstruction — Repeat balloon dilation is often effective in patients who develop recurrent obstruction, with gradient reduction of at least 50 percent in most patients.
In one report, repeat BAV was performed in 34 patients from an initial series of 298 patients, including 70 neonates [54]. Repeat intervention was required more often in newborns than in older patients (26 versus 8 percent). The mean peak-to-peak gradient was reduced from 67 to 36 mmHg; however, AR increased immediately in 26 percent of patients and was at least moderate in 24 percent. Among 33 survivors (one surgery-related death occurred), 27 (81 percent) were asymptomatic and 6 had surgery for residual stenosis and/or AR.
Aortic regurgitation — Moderate to severe AR occurs in approximately 15 percent of cases following BAV and can worsen over time. Older patients (>11 years old) are more likely to develop AR following BAV compared with younger patients [52]. In addition, valve morphology appears to influence outcome after BAV; valves with lesser fusion and larger openings have higher rates of leaflet tears which are associated with AR [55]. Management of AR in children includes medical therapy (eg, angiotensin-converting enzyme [ACE] inhibitors) and/or surgery (valve repair or replacement). AVR is discussed below. Treatment of AR in children is reviewed in greater detail separately. (See "Aortic regurgitation in children", section on 'Management'.)
Surgical options — Surgical options for valvar AS include valvotomy and valve replacement (either with mechanical or bioprosthetic valve or with pulmonary autograft [ie, Ross procedure]).
●Surgical valvotomy – The major alternative to BAV for congenital valvar AS is surgical valvotomy. Reports of comparative data between BAV and surgical valvotomy have drawn variable conclusions. Some studies report equivalent outcomes [56,57]; while others have concluded that surgical intervention may be superior to BAV [58,59]. In a meta-analysis of 18 observational studies, BAV was associated with an earlier time to reintervention compared with surgical intervention, but survival, incidence of moderate or severe AR, and risk of AVR were similar between the two techniques [60].
●Valve replacement – AVR for treatment of congenital valvar AS is usually reserved for adult patients, in whom balloon dilation is generally ineffective. AVR also may be performed in children with congenital valvar AS who develop severe AR following BAV. Mechanical prosthetic valves are preferred because of better long-term durability even though they require systemic anticoagulation. Bioprosthetic valves reduce the need for anticoagulation but have a high failure rate in children and young adults, approaching 20 percent within a follow-up period of three years [61]. (See "Mechanical prosthetic valve thrombosis or obstruction: Clinical manifestations and diagnosis" and "Bicuspid aortic valve: General management in adults".)
In children who undergo AVR, mortality and repeat valve replacement are common. In a review of 160 children who underwent AVR from a single center between the years 1974 and 2004, 19 percent of children died without a second AVR, 34 percent received a second AVR, and 47 percent remained alive without replacement [62]. A younger age at initial AVR was a risk factor for both death and repeat valve replacement. A younger age was associated with the presence of other cardiac anomalies, which increased the risk of death, and with outgrowth of the original prosthetic valve requiring subsequent replacement.
Echocardiographic surveillance is typically performed every 6 to 12 months for children with mechanical valves, and every 3 to 6 months for children with bioprosthetic valves due to the differences in valve durability; however, there are no published guidelines. More frequent surveillance is indicated for valves that show changing degrees of stenosis or regurgitation.
●Pulmonary autograft (Ross procedure) – An alternative to valve replacement in children with congenital valvar AS is the Ross or Ross/Konno procedure [63-65]. With this procedure, the pulmonary valve is transplanted to the aortic position, and a homograft conduit is implanted from the RV to the pulmonary artery. Use of this technique has been limited by the high rates of failure of the pulmonary autograft and deterioration of the right heart homografts.
In two meta-analyses of published studies on the Ross procedure in children, early mortality was 4.2 percent, late mortality was 0.6 percent, and the rate of autograft deterioration was 1.4 to 1.9 percent per year [66,67]. In one analysis, a higher rate of autograft deterioration was observed in patients with predominantly AR, presumably due to progressive annular and aortic root dilation, which has led some to avoid the Ross procedure in this setting [66]. Newer modifications to prevent progressive dilation of the autograft aortic root include placement of a bioabsorbable ring at the sino-tubular junction, which was reported to reduce the risk of subsequent AR in a case series of 19 patients [68]. (See "Indications for valve replacement for high gradient aortic stenosis in adults".)
A subsequent multicenter Italian study of 305 children who underwent the Ross procedure from 1990 to 2012 with a median follow-up of 8.7 years also demonstrated significant postoperative mortality (10 in-hospital deaths and 12 late deaths) and morbidity [69]. For survivors, freedom from autograft reoperation was 86 and 76 percent at 10 and 15 years, respectively. In this cohort, mortality was higher in infants compared with older patients.
FOLLOW-UP CARE
Sports participation — The 2015 scientific statement of the American Heart Association and American College of Cardiology (AHA/ACC) provides competitive athletic participation guidelines for patients with congenital heart disease (CHD), including valvar aortic stenosis (AS) [70]:
●For patients with untreated AS or residual AS following surgery or balloon dilation, participation in sports is considered according to severity:
•Mild AS (mean gradient <25 mmHg or maximum instantaneous gradient <40 mmHg): Patients can participate in all sports if they have a normal electrocardiogram (ECG), normal exercise tolerance, and no history of exercise-related chest pain, syncope, or tachyarrhythmia.
•Moderate AS (mean gradient 25 to 40 mmHg or maximum instantaneous gradient 40 to 70 mmHg): Patients may participate in low-intensity static or low- to moderate-intensity dynamic sports (class IA, IB, and IIA) (figure 1) if they have only mild or no left ventricular (LV) hypertrophy on echocardiogram, no evidence of LV strain on ECG, and a normal maximum exercise stress test without evidence of ischemia or tachyarrhythmia, with normal exercise duration and blood pressure response.
•Severe AS (mean gradient >40 mmHg or maximum instantaneous gradient >70 mmHg): Patients can participate only in low-intensity (class IA) sports (figure 1).
●Patients with moderate or severe aortic regurgitation (AR) following surgery or balloon dilation may participate in sports according to recommendations for adults with chronic AR. (See "Natural history and management of chronic aortic regurgitation in adults", section on 'Recommendations for physical activity and exercise'.)
In our practice, we typically use less restrictive sports participation limitations in patients with AS, with modest restriction only for those with gradients >60 mmHg until an intervention can be performed. We take an aggressive approach to gradient reduction in patients with AS and do not typically follow a patient with a gradient >55 mmHg without intervention. (See 'Indications for intervention' above.)
There is evidence that exercise restriction following successful balloon aortic valvotomy (BAV) may not be necessary. This was illustrated by a retrospective review of 528 patients who underwent BAV at our tertiary center from 1984 to 2008 [71]. At a median follow-up of 12 years, there were 63 deaths including sudden unexpected death (SUD) in six patients, five of which occurred at ≤18 months of age. In patients >4 years of age, exercise restriction was prescribed in 43 percent and included the one patient with SUD. As a result, we conclude that SUD is extremely rare after BAV, and there is no beneficial effect for exercise restriction in these patients.
Physical activity and exercise in children with CHD are discussed in greater detail separately. (See "Physical activity and exercise in patients with congenital heart disease".)
Antibiotic prophylaxis — Antibiotic prophylaxis to prevent bacterial endocarditis is not recommended in patients with valvar AS, except in those with a prior history of endocarditis or who require prosthetic heart valves. Patients with valvar AS are at increased risk of endocarditis; however, as there is considerable uncertainty regarding the efficacy of the practice of subacute bacterial endocarditis prophylaxis, guidelines emphasize prophylaxis only for those patients at greatest risk from the sequelae of endocarditis, a group into which most patients with native AS do not fall. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)
Family screening — Bicuspid aortic valve is the most frequent cause of AS in children, and it may be heritable. In one study that screened siblings of children with bicuspid aortic valve by echocardiography, 10 percent of 207 siblings (median age seven years) also had bicuspid aortic valve [72]. We recommend echocardiographic screening for bicuspid aortic valve (and ascending aortic dilatation) in first-degree relatives of patients with bicuspid aortic valve (as recommended in the 2008 AHA/ACC adult congenital heart disease guidelines) [73]. (See "Bicuspid aortic valve: Management during pregnancy", section on 'Heritability'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Congenital heart disease in infants and children".)
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Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)
●Basics topic (see "Patient education: Aortic stenosis (The Basics)")
SUMMARY AND RECOMMENDATIONS — The most common congenital left ventricular outflow tract obstructive lesion is valvar aortic stenosis (AS).
●In valvar AS, the most common morphology is a bicommissural or bicuspid aortic valve, which is associated with both congenital and acquired AS. (See 'Etiology' above and 'Anatomy' above.)
•In adults with AS, bicuspid aortic valve is the most common valve anomaly. (See "Clinical manifestations and diagnosis of bicuspid aortic valve in adults".)
•Children with congenital AS due to bicuspid aortic valve are at risk for other cardiovascular anomalies, especially coarctation of the aorta. (See 'Etiology' above.)
●The clinical findings vary depending on the severity of the stenotic lesion.
•Most children with valvar AS, even those with moderate disease, are relatively asymptomatic.
•Critical AS in the neonate results in severe restricted outward flow and is fatal in patients without intervention. Neonates with critical AS will present with poor peripheral perfusion and cyanosis as the ductus arteriosus closes. Physical findings include a hyperactive precordium and poor peripheral pulses. A cardiac murmur is frequently not heard because of poor cardiac output. A gallop rhythm may also be present. (See 'Critical aortic stenosis' above.)
•Infants with severe, but not critical, AS may present with heart failure, which is characterized by poor feeding, growth failure and tachypnea, and physical findings including hyperactive precordium, ejection murmur, and often hepatomegaly and peripheral edema. (See 'Infantile aortic stenosis' above.)
•Older children with AS are rarely symptomatic and are generally identified by the presence of the characteristic harsh ejection murmur, which may be accompanied by an ejection click. (See 'Older children' above.)
●Patients with congenital valvar AS often have progressive obstruction and are at increased risk for infectious endocarditis and sudden death. The risk of mortality is greater in patients with more severe disease who have significant obstruction and aortic regurgitation. (See 'Clinical course' above.)
●The diagnosis of valvar AS may be made on physical findings and generally confirmed by echocardiography (movie 1 and movie 4). Cardiac catheterization is performed if the severity/diagnosis remains uncertain, if there are associated defects that cannot be completely evaluated noninvasively, or if balloon aortic valvuloplasty is anticipated. (See 'Diagnosis' above.)
●Treatment is indicated for patients who present with severe obstruction, which is especially urgent in the critically ill neonate and infant with heart failure. In other patients, the decision to treat is based on the peak-to-peak systolic gradient obtained during cardiac catheterization (see 'Indications for intervention' above):
•Patients with a peak-to-peak systolic gradient >50 mmHg should be treated, as they are at high risk for ventricular arrhythmias and sudden death due to progressive obstruction from their lesions.
•Patients with a peak-to-peak systolic gradient <25 mmHg can be followed medically on a regular basis as they have mild disease and are at low risk for mortality and morbidity.
•Data are less conclusive of patients with a peak-to-peak systolic gradient between 25 and 50 mmHg, as they are at intermediate risk for poor outcome. In our practice, we monitor their clinical status closely and intervene if there is a worsening of the gradient or development of symptoms.
●Definitive therapy consists of reducing the degree of valvar stenosis. In our center, the treatment of choice is balloon valvuloplasty, regardless of the age and size of the patient, which has largely replaced surgical valvotomy. Aortic valve replacement is usually reserved for adults with congenital AS in whom balloon dilation is generally ineffective. (See 'First-line treatment' above and "Indications for valve replacement for high gradient aortic stenosis in adults".)
●Antibiotic prophylaxis to prevent bacterial endocarditis is not recommended in patients with valvar AS, except in those with a prior history of endocarditis or who require prosthetic heart valves. (See "Prevention of endocarditis: Antibiotic prophylaxis and other measures".)
ACKNOWLEDGMENT — The editorial staff at UpToDate would like to acknowledge John Keane, MD, who contributed to an earlier version of this topic review.
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