Acyanotic cardiac lesions represent a significant portion of all congenital heart disease. Although acyanotic shunt lesions are discussed in Chapter 7, this chapter focuses on acyanotic valve and ventricular outflow tract lesions as well as common vascular abnormalities. The chapter begins with a discussion of the semilunar valves (aortic valve and pulmonary valve) and their associated ventricular outflow tracts. Next, lesions of the atrioventricular valves (mitral valve and tricuspid valve) are addressed. Finally, the chapter concludes with a discussion of aortic arch anomalies and peripheral pulmonary stenosis. Each section begins with a description of the normal cardiac structures prior to describing the lesions that affect them. Tables 8-1 and 8-2 summarize the salient points from each section. Endocarditis prophylaxis for various lesions is discussed in Chapters 14 and 16.
| Lesion | Common Etiologies | Classic Murmur | Other Examination Findings | Common Presentation | ECG | CXR |
|---|---|---|---|---|---|---|
| Valvar aortic stenosis | Infant: unicuspid valve Children: bicuspid aortic valve | SEM loudest at RUSB with radiation to neck | Systolic ejection click if bicuspid valve present | Neonates: critical AS presents with low cardiac output/shock Children: asymptomatic murmur | LVH may be present | Infants: pulmonary edema, cardiomegaly Children: usually normal |
| Aortic regurgitation | Bicuspid aortic valve | Medium- to high-frequency diastolic murmur at left sternal border | Wide pulse pressure Bounding pulses | Asymptomatic murmur | LVH may be present | Cardiomegaly may be present |
| Valvar pulmonary stenosis | Conical valve or unicuspid valve Often associated with Noonan syndrome | SEM loudest at LUSB with radiation to back | Systolic ejection click may be present | Neonates: critical PS presents with cyanosis Children: asymptomatic murmur | RVH RAE may be present | Infants: decreased pulmonary vascular markings Children: usually normal |
| Mitral stenosis | Leaflet, chordae, or papillary muscle abnormalities | Low-frequency, mid-diastolic murmur at apex | Second heart sound can be narrowly split if pulmonary HTN present | Usually presents in infancy with tachypnea, frequent pneumonia, FTT | LAE | May show pulmonary edema |
| Mitral regurgitation | Leaflet, chordae, or papillary muscle abnormalities | Holosystolic, blowing murmur at apex | MS murmur if significant MR exists | Neonates: tachypnea, FTT Children: exercise intolerance | LAE LVH | Cardiomegaly may be present |
| Ebstein anomaly | Tethered septal and posterior tricuspid valve leaflets | Holosystolic murmur at LLSB | PS murmur if significant TR exists | Mild: murmur, arrhythmias, fatigue with exertion Severe: cyanosis in infancy | RAE | Cardiomegaly |
| Aortic coarctation | Associated with left-sided obstructive lesions and Turner syndrome | SEM loudest at LUSB with radiation to back Murmur can be absent | Upper extremity HTN Blood pressure gradient between RUE and LE and diminished femoral pulses | Neonates: may present with low cardiac output/shock Children: upper extremity HTN | LVH may be present | Infants: pulmonary edema, cardiomegaly Children: 3 sign, rib notching |
| Lesion | Signs/Symptoms That Should Prompt Concern |
|---|---|
| LVOT obstructive lesion |
|
| RVOT obstructive lesion |
|
| Mitral stenosis |
|
| Mitral regurgitation |
|
| Ebstein anomaly |
|
| Aortic coarctation |
|
The aortic valve connects the left ventricle to the aorta. The normal aortic valve is made up of 3 cusps and does not have a tensor apparatus. Aortic stenosis (AS) results from obstruction at any point between the left ventricle and the aorta. It can occur below the valve in the left ventricular outflow tract (subvalvar AS), at the level of the valve itself (valvar AS), or above the valve in the proximal aorta (supravalvar AS). AS in some form accounts for 3% to 8% of all congenital heart disease.1
Congenital valvar AS is a malformation of the aortic valve that occurs before birth and results in varying degrees of obstruction to blood flow. Valvar AS accounts for 75% of congenital AS. Although not always stenotic, the most common congenital lesion of the aortic valve is a bicuspid aortic valve, which occurs in 1% of the population.1 A bicuspid aortic valve occurs when 2 cusps fuse to form a valve that functionally has 2 cusps instead of 3. Unicuspid aortic valves have a slit-like opening and are associated with critical AS. Less commonly, stenosis results from a hypoplastic valve annulus with normal cusps. Valvar AS occurs more often in males than females. Additional congenital heart defects are present in 20% of patients including patent ductus arteriosus (PDA), aortic coarctation, and ventricular septal defect (VSD).1
The congenital aortic valve abnormality decreases the size of the orifice through which blood flows from the left ventricle to the aorta causing left ventricular outflow obstruction. A unicuspid valve typically results in “critical AS” in which severe obstruction prevents adequate antegrade blood flow across the aortic valve and systemic perfusion is dependent on right-to-left flow across the PDA. In patients with a bicuspid aortic valve, the orifice size can be relatively preserved during life. If the orifice size does not increase normally with growth, then obstruction develops later in childhood or adolescence. The left ventricle hypertrophies over time to maintain normal wall stress in the setting of the increased afterload, which predisposes the myocardium to chronic ischemia and can lead to left ventricular dilatation and systolic dysfunction.
Newborns with severe aortic obstruction may have ductal-dependent systemic circulation after birth. If perfusion to the head and neck and upper extremity vessels as well as the descending aorta is dependent on flow from the pulmonary artery through a PDA, this is termed “critical AS.” If not identified either prenatally or before ductal closure, infants with critical AS will present in shock in the first week of life as the ductus arteriosus closes and systemic perfusion is compromised. Such patients often appear well immediately after birth, although frequently they are “comfortably tachypneic.” They usually do not have differential saturations between the upper and lower body since the ductus supplies the ascending as well as descending aorta. Following ductal constriction, these infants appear pale and often have a systolic ejection murmur at the right upper sternal border as well as a gallop. Peripheral pulses will be diminished. Laboratory testing will reveal a significant metabolic acidosis. Some neonates with significant (although not critical) valvar AS may tolerate ductal closure. These patients often present within the first few months of life with severe congestive heart failure due to left ventricular failure. They present with poor feeding, tachypnea, and growth failure, and physical examination shows a systolic ejection murmur, gallop, and decreased peripheral pulses.
Only 10% of patients with congenital valvar AS present during infancy. Instead, most patients with a bicuspid valve are diagnosed later. Some are referred to a pediatric cardiologist to evaluate a cardiac murmur. Dyspnea, chest pain, or syncope with exercise may be present if the stenosis and resultant left ventricular hypertrophy are substantial. On physical examination, a thrill may be present in the suprasternal notch. The first heart sound will be normal, and splitting of the second sound may not be present in severe AS due to prolonged left ventricular ejection. Patients with a bicuspid aortic valve may have a systolic ejection click that shortly follows S1; the click is best heard at the left lower sternal border or apex. The characteristic murmur of AS is a systolic ejection murmur that begins shortly after S1 and is crescendo–decrescendo in shape (Figure 8-1). The murmur is best heard at the right upper sternal border and can radiate to the carotid arteries. As the stenosis worsens, the murmur becomes louder and harsher and peaks later in systole.
Figure 8-1
Left ventricle pressure (LVP) and aortic pressure (AOP) tracings shown with simultaneous electrocardiogram (ECG) and auscultatory characteristics in a patient with left ventricular outflow tract obstruction. Due to the obstruction, left ventricular pressure exceeds aortic pressure during systolic ejection. The midsystolic murmur (MSM) begins after the first heart sound (S1) and is crescendo–decrescendo in character. The murmur is loudest at the peak of left ventricular ejection when the pressure difference between ventricle and aorta is the greatest. During late systole, the pressure difference diminishes and the murmur ends prior to aortic valve closure (A2). (Reproduced, with permission, from Fauci AS, Kasper DL, Braunwald E, et al. Harrison’s Principles of Internal Medicine. 17th ed. New York, NY: McGraw-Hill; 2008.)
Chest radiograph (CXR) is usually normal in isolated AS unless left ventricular failure is present, in which case cardiomegaly can be observed. Patients with significant obstruction may show signs of left ventricular hypertrophy on electrocardiogram (ECG), but typically the tracing is normal. Clinical symptoms and physical examination can suggest AS, but the test of choice to confirm the diagnosis is echocardiography. The echocardiogram can demonstrate the morphology of the aortic valve (Figure 8-2) and can characterize the degree of obstruction using Doppler to estimate the pressure gradient between left ventricle and aorta during systole. The echocardiogram can also determine left ventricular size (hypertrophy, dilatation) and systolic function (Figure 8-3A). In neonates with critical AS, the echocardiogram is crucial in determining if the aortic valve and left ventricle are large enough to support a biventricular circulation. Cardiac catheterization can be diagnostic and therapeutic in patients with AS and is considered the gold standard for measuring the pressure gradient from left ventricle to ascending aorta. Angiography can also differentiate left ventricular size and function and the effective aortic valve orifice (Figure 8-3B).
Figure 8-2
A. Picture illustrating a bicuspid aortic valve when open and closed. (Reproduced, with permission, from Siu SC, Silversides CK. Bicuspid aortic valve disease. J Am Coll Cardiol. 2010;55:2789-2800. Copyright © Elsevier Inc., All rights reserved.) B. Echocardiogram showing parasternal short axis view of an open bicuspid aortic valve in an adolescent. The aortic valve (AoV) is shown in cross-section with the characteristic “fish mouth” appearance.
Figure 8-3
A. Echocardiogram showing the apical 4-chamber view in a neonate with severe valvar aortic stenosis. The left ventricle (LV) is severely dilated and the aortic valve (AoV) is unicuspid and hypoplastic. LA, left atrium; MV, mitral valve. B. Left ventricular angiography in the same patient highlighting the dilated LV and the small orifice through which contrast flows from LV to aorta.
Patients who present in infancy with ductal-dependent circulation or heart failure require intervention. If the left ventricle, mitral valve annulus, and aortic valve annulus are of adequate size, a 2-ventricle circulation is viable. In these patients, transcatheter balloon dilation of the aortic valve is preferred over open surgical valvotomy in most centers. Balloon dilation is effective, but many patients will develop aortic insufficiency after dilation. Patients with significant aortic regurgitation or refractory stenosis will require a surgical intervention. Patients who require transcatheter intervention in infancy often require repeat balloon dilation in childhood and many ultimately require surgical intervention.
Patients who present in childhood or adolescence with congenital AS usually can be managed expectantly as most are asymptomatic with mild obstruction. Medical management of these patients includes appropriate exercise restrictions and serial evaluations of the aortic valve obstruction with echocardiogram. Guidelines for exercise restriction in congenital AS exist; patients with mild AS and no symptoms can participate in all competitive sports.2 Of note, patients with a bicuspid aortic valve can also develop valve regurgitation and dilatation of the ascending aorta that must also be considered when determining exercise restrictions. Exercise guidelines for patients who have undergone prosthetic aortic valve replacement are discussed in the aortic regurgitation section.
In children or adolescents who do require valve intervention, balloon valvuloplasty is generally preferred to surgery as the initial intervention. Typically, balloon valvuloplasty is performed if the catheter-derived gradient across the valve is >50 mm Hg and there is no significant aortic insufficiency. Children or adolescents with progressive aortic regurgitation or stenosis that is refractory to balloon dilation typically require surgery.
Surgical options in infants and small children include replacement of the diseased aortic valve with an aortic homograft or with a pulmonary autograft (Ross procedure). In the Ross procedure, the aortic valve is completely removed and the patient’s pulmonary valve is transferred into the aortic position. A conduit is then placed from right ventricle to pulmonary artery. In larger children and adolescents, mechanical or bioprosthetic valves can also be used. Mechanical valves are durable but require anticoagulation with warfarin. Bioprosthetic valves may not require anticoagulation but have limited longevity and durability compared to mechanical valves.
Subvalvar AS results when obstruction to left ventricular outflow exists below the aortic valve. It represents 10% to 20% of AS in children and, like valvar AS, is more common in males. Subvalvar AS is most often caused by a subaortic membrane, a ridge of membranous or fibromuscular tissue that encircles the left ventricular outflow tract. Subaortic obstruction can also occur in hypertrophic obstructive cardiomyopathy, but this is discussed in Chapter 13. Other congenital cardiac anomalies such as VSD, aortic coarctation, atrioventricular septal defect, valvar AS, and mitral valve abnormalities are often found in association with a subaortic membrane.1
The pathophysiology of subvalvar AS is similar to that of valvar AS: Afterload is increased on the left ventricle, and over time, this results in left ventricular hypertrophy. As in valvar disease, severe subaortic obstruction and ventricular hypertrophy can result in endocardial ischemia and fibrosis. In patients with subaortic disease, the aortic valve can be trileaflet or bicuspid. The valve leaflets thicken due to the damage from the turbulent flow below the valve that may lead to valvar stenosis as well as aortic regurgitation.
Patients with subvalvar AS usually present with a heart murmur in the absence of symptoms. In other patients with accompanying cardiac lesions such as aortic coarctation, the subaortic obstruction will be diagnosed incidentally at the time of echocardiogram. If obstruction is severe, symptoms can mimic valvar AS. Physical examination will show a systolic ejection murmur loudest at the left midsternal border that radiates to the suprasternal notch and neck. The murmur will resemble that of valvar AS, but patients with subvalvar obstruction will not have a systolic click, an important finding that can help differentiate between valvar and subvalvar obstruction.
The ECG can be normal, but may also show left ventricular hypertrophy. Echocardiography is needed to establish the diagnosis and to determine the severity of the obstruction (Figure 8-4). The echocardiogram will define associated cardiac lesions and determine if the aortic valve has incurred damage from the turbulent subaortic flow. Cardiac catheterization can be used to determine the gradient from left ventricle to aorta. However, catheterization is used less often in the evaluation of subaortic obstruction because transcatheter interventions are not used for treatment.
The treatment of choice for subaortic obstruction is surgical resection of the obstructive left ventricular outflow tract tissue. Although often successful, complications include surgically created VSDs and complete heart block.
Mild subaortic obstruction can remain stable for years but may progress. Indications for surgery are not universally agreed upon, but patients with progressive obstruction should undergo operation. Likewise, patients with progressive left ventricular hypertrophy, left ventricular systolic dysfunction, or symptoms (eg, chest pain, exercise intolerance, syncope) should have resection. Progressive aortic regurgitation is also an indication for membrane resection. The valvar AS guidelines for exercise restriction can be applied to those with subvalvar obstruction.2
Supravalvar AS is obstruction to left ventricular outflow above the aortic valve and is the least common form of congenital AS. Roughly 30% to 50% of patients with supravalvar AS have Williams syndrome.1 The lesion can be familial in patients who do not have other features of Williams syndrome. In half of the patients, the lesion is sporadic. In those with the familial form, abnormal elastin gene expression is thought to cause the supravalvar narrowing. The stenosis is typically localized to the sinotubular junction, but some can have narrowing of the entire ascending aorta. Other lesions associated with supravalvar AS can include branch pulmonary artery stenosis, aortic coarctation, VSD, and bicuspid aortic valve.1
The physiology of supravalvar AS is similar to subvalvar and valvar stenosis. However, in supravalvar AS, the coronary arteries are uniquely affected because they arise proximal to the obstruction. The coronaries are exposed to elevated systolic pressure that can lead to abnormal remodeling. Also, the coronary ostia may be compromised due to the supravalvar stenosis. As a result, patients with supravalvar AS are at risk for ischemia and endocardial fibrosis. In addition, because the sinotubular junction does not expand normally, shear stress is placed on aortic valve leaflets, leading to thickening and damage in many patients.
Most patients are diagnosed when referred for an asymptomatic murmur. Similar to valvar and subvalvar stenosis, patients with supravalvar AS can experience chest pain or syncope with exercise if severe obstruction exists. The quality and location of the murmur are similar to valvar AS, but a systolic click is uncommon.
ECG can show left ventricular hypertrophy but is typically normal. Echocardiography is necessary to make the diagnosis and to evaluate the severity of obstruction (Figure 8-5). Cardiac catheterization can determine the degree of obstruction, and angiography defines the anatomy of the ascending aorta and coronary arteries. However, at catheterization, patients with supravalvar AS are at increased risk of cardiac arrest, likely due to impairment of coronary flow during catheter manipulation. It is important to use noninvasive methods to evaluate other arteries that can be affected by the elastin abnormality including the aortic arch branches, pulmonary arteries, and renal arteries.
Like subvalvar AS, surgery is the treatment of choice for supravalvar obstruction. Criteria for intervention are similar to those used for valvar AS. Surgical repair consists of patch plasty of 1, 2, or all 3 aortic sinuses. Exercise restrictions for patients with valvar AS can also be applied to patients with supravalvar AS.2
Aortic valve regurgitation (AR) is uncommon in the pediatric population and can be congenital or acquired. Congenital causes include primary valve abnormality, VSDs, subaortic membranes, and aortic root dilation associated with connective tissue disorders. The most common primary valve abnormality is a bicuspid aortic valve. Some VSDs that are located close to the aortic valve (ie, conoventricular or conal septal hypoplasia types) lead to valve insufficiency via leaflet prolapse into the defect. Subaortic membranes cause turbulence below the aortic valve that can damage the valve cusps and lead to regurgitation. Aortic root dilation in the setting of Marfan syndrome or Ehlers-Danlos syndrome can lead to root dilation that ultimately compromises coaptation of the aortic valve leaflets. Acquired causes of AR also exist and include endocarditis, rheumatic heart disease, infectious aortitis, and valve dysfunction after transcatheter balloon dilation for AS.3
In the presence of AR, blood flows backward from the aorta to the ventricle during diastole. This regurgitant volume must be ejected again during the next cardiac cycle and, thus, acts as a volume load for the left ventricle, leading to ventricular dilation. As the left ventricle dilates, the myocardium hypertrophies to maintain wall stress. Forward flow is maintained, but over time, systolic dysfunction can result, eventually leading to symptoms of heart failure. Aortic diastolic pressure will be lower due to the valve regurgitation and, if severe, coronary perfusion can be reduced, further compromising left ventricular performance.
Mild to moderate AR can be tolerated very well for years. As discussed in the section on valvar AS, patients with a bicuspid valve rarely present with symptoms in childhood or adolescence. The onset of severe regurgitation will often be associated with clinical signs of congestive heart failure including shortness of breath and failure to thrive. Chest pain with exercise and syncope can also occur but are less common. Patients with severe AR may have tachypnea, tachycardia, and a low diastolic blood pressure on examination. The diastolic leakage of blood from the aorta to the ventricle and the increased volume of blood ejected during systole will lead to increased systolic pressure, a wide pulse pressure, and bounding or “water hammer” pulses on palpation (Corrigan pulse). Even patients with mild AR will have a medium- to high-frequency early diastolic murmur (Figure 8-6). It is heard best at the left sternal border in those with valvular disease and at the right upper sternal border in patients with aortic root dilation. Due to an increased stroke volume, a systolic ejection murmur can also be present that resembles the murmur in valvar AS. Also, true valvar AS can accompany AR, particularly in patients with a bicuspid aortic valve.
Figure 8-6
Left ventricle pressure (LVP) and aortic pressue (AOP) tracings shown with simultaneous electrocardiogram (ECG) and auscultatory characteristics in a patient with aortic regurgitation. During diastole, AOP always exceeds LVP. The regurgitant orifice at the aortic valve allows blood to flow from aorta to left ventricle during diastole, creating an early diastolic murmur (EDM) that starts soon after aortic valve closure (A2). (Reproduced, with permission, from Fauci AS, Kasper DL, Braunwald E, et al. Harrison’s Principles of Internal Medicine. 17th ed. New York, NY: McGraw-Hill Companies; 2008.)
A second diastolic murmur can also be present called an Austin Flint murmur. It results from turbulent inflow of blood from the left atrium into the left ventricle. The aortic regurgitant flow impedes the opening of the anterior mitral valve leaflet during left ventricular filling, leading to a relative mitral stenosis murmur. The Austin Flint murmur is low pitched, occurs in late diastole, and is appreciated near the apex.
Patients with significant regurgitation will often have cardiomegaly on CXR due to left ventricular dilatation. The ECG may show left ventricular hypertrophy. Echocardiography is essential in evaluating AR because it outlines aortic valve morphology and aortic root size as well as left ventricular size and function (Figure 8-7). Using color Doppler echocardiography, one can qualitatively describe the severity of the regurgitation. Cardiac magnetic resonance imaging (MRI) can be used to determine left ventricular volume and ejection fraction and can quantify the aortic valve regurgitant fraction.
Although data in children are limited, angiotensin-converting enzyme (ACE) inhibitors can be used to treat AR; decreasing afterload and diastolic pressure can decrease the pressure gradient between the aorta and the left ventricle, thus decreasing the volume of regurgitated blood. The presence of severe AR with any symptoms is an indication for surgical intervention. Patients with severe insufficiency who are asymptomatic should be referred for surgery if left ventricular systolic dysfunction is present or if there is progressive left ventricular enlargement.3 Currently, no transcatheter strategies are available in children.
The primary surgical principle in managing AR in the pediatric population is to avoid valve replacement when possible. In infants and young children, replacement would require aortic homografts, which are known to have accelerated calcification and failure. Although most children with significant AR will eventually require valve replacement, delay into adolescence or early adulthood makes both bioprosthetic and mechanical valves viable options. Valve choice is dictated not only by size, but also by the need for anticoagulation that is required for all mechanical valves and some prosthetic valves. Aortic valve repair can involve commissurotomies and leaflet extensions with pericardial patches as well as other strategies.
Asymptomatic patients with mild or moderate regurgitation but normal left ventricular end-diastolic size do not require exercise restriction. Patients with mild or moderate regurgitation and any symptoms should refrain from competitive sports. Patients with mechanical or bioprosthetic aortic valves with normal valve function and normal left ventricular function may participate in moderate static and moderate dynamic competitive sports. Patients taking anticoagulation, however, should refrain from participation in any sports that risk body contact or trauma.4
Like the aortic valve, the normal pulmonary valve is made up of 3 cusps and has no tensor apparatus. Obstruction to right ventricular outflow can occur below the pulmonary valve within the outflow tract itself (subvalvar pulmonary stenosis), at the level of the valve (valvar pulmonary stenosis), or above the pulmonary valve within the proximal main pulmonary artery (supravalvar pulmonary stenosis). All forms of pulmonary stenosis and pulmonary regurgitation are addressed in this section.
In 80% to 90% of cases, right ventricular outflow obstruction is due to congenital valvar pulmonary stenosis (PS). The diagnosis makes up 8% to 10% of all cases of congenital heart disease.5 In severe cases, the valve is conical with no separation into valve leaflets, with a hypoplastic valve annulus. There can be fusion of leaflets, resulting in a unicuspid or bicuspid valve. Other patients have a “dysplastic valve” defined as a trileaflet valve with thickened cusps and a hypoplastic annulus. Dysplastic valves are typical of Noonan syndrome.5
The valve abnormality decreases the orifice through which blood flows from the right ventricle. Similar to the effect that AS has on the left ventricle, PS increases afterload on the right ventricle. The obstruction causes right ventricular pressure to rise. The right ventricle hypertrophies to normalize wall stress. Over time, the ventricle can dilate and ultimately show systolic failure. Severe ventricular hypertrophy causes abnormal right ventricular compliance and can lead to elevated right atrial pressure. In these patients, right atrial pressure can exceed left atrial pressure during exercise, and cyanosis may be appreciated due to right-to-left shunting at a patent foramen ovale.
Neonates with severe pulmonary valve obstruction can have right ventricular hypoplasia, a significant right-to-left shunt across the patent foramen ovale, and inadequate antegrade flow across the pulmonary valve. These patients will be cyanotic after birth with ductal dependent pulmonary blood flow. This condition is referred to as “critical PS.”
Most patients with PS are diagnosed after referral for an asymptomatic murmur as symptoms are rarely present in childhood. If severe obstruction is present, the patient may have symptoms of exertional fatigue due to the inability of the right ventricle to increase its output. Rarely, patients with significant stenosis may have chest pain or syncope with exercise. Neonates with critical PS will be cyanotic after birth. Typically, cardiac output is preserved because the right-to-left flow across the patent foramen ovale is unobstructed.
On auscultation, the characteristic murmur of valvar PS is ejection type (crescendo–decrescendo) and is loudest at the left upper sternal border with radiation to the back. The intensity of the murmur increases with the degree of obstruction. The first heart sound is normal. Splitting of the second heart sound increases with the degree of obstruction as right ventricular ejection is prolonged. Many patients with mild or moderate stenosis will have a systolic ejection click heard after S1. Those with significant obstruction may have a palpable systolic thrill along the left sternal border. In critical PS, the systolic murmur may be soft because of decreased flow across the pulmonary valve in setting of right-to-left flow across the patent foramen ovale. The murmur of a PDA is likely to be present in the left upper chest in these patients.
Patients with mild pulmonary valve obstruction will often have a normal ECG. Those with moderate or severe stenosis may show right axis deviation with signs of right ventricular hypertrophy or right atrial enlargement. CXR can show a prominent main pulmonary artery due to poststenotic dilatation. Cardiomegaly is uncommon unless right ventricular failure or other structural cardiac defects are present. In contrast, infants with critical PS will have cardiomegaly and significantly diminished pulmonary vascular markings.
Echocardiography is crucial in making the diagnosis of PS. The severity of obstruction can also be estimated using Doppler measurements. When needed, the gradient can be precisely measured at cardiac catheterization.
In children and adolescents with mild stenosis, the obstruction rarely progresses, and only serial observation is required. The obstruction in those with moderate stenosis is more likely to progress, particularly during early periods of rapid growth. Patients with severe stenosis will often exhibit progression of obstruction and should be followed closely. Patients who are symptomatic or those with significant obstruction and elevated right ventricular pressure should undergo pulmonary valve intervention.5
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