Valvar Pulmonary Stenosis 

Updated: Jun 26, 2014
Author: Syamasundar Rao Patnana, MD; Chief Editor: Howard S Weber, MD, FSCAI 

Overview

Background

Diseases of the pulmonary valve are most often congenital, and only rarely do acquired disorders such as carcinoid and rheumatic fever affect the pulmonary valve.[1] The pulmonary valve may be stenotic or atretic, or the leaflets of the valve may be absent. Pulmonary stenosis may be valvar, supravalvar, or subvalvar (ie, double-chambered right ventricle); it may also be in the branch pulmonary arteries. These lesions are collectively described as right ventricular outflow tract obstructions. In this article, only valvar pulmonary stenosis is reviewed.

A stenotic pulmonary valve usually occurs without associated congenital abnormalities, although it may be associated with other structural abnormalities of the heart. To distinguish the former from the latter, terms such as pulmonary stenosis with a normal aortic root or pulmonary stenosis with an intact ventricular septum have been used. However, the term isolated pulmonary valve stenosis is preferred.[1] The term isolated may be used even when a patent foramen ovale or a small atrial septal defect is present. The term congenital need not be used because most are congenital.

Pathologic Anatomy

Pathologic features of the stenotic pulmonary valve vary.[2] The most common pathology is a dome-shaped pulmonary valve. The fused leaflets of the pulmonary valve protrude from their attachment into the pulmonary artery as a conical, windsock-like structure. The size of the pulmonary valve orifice varies from a pinhole to several millimeters. The orifice is most usually central but can be eccentric. Raphae, presumably fused commissures of the valve, extend from the stenotic orifice to a variable distance down into the base of the dome-shaped valve. The number of the raphe may vary from 0-7. Relatively uncommon variants are unicommissural, bicuspid, and tricuspid valves. The valve annulus is abnormal in most cases, and the fibrous back bone is partially or completely lacking; therefore, a true annulus may not be present.[2]

Hypoplasia of the pulmonary valve ring and dysplastic pulmonary valves may be present in a few of patients. Pulmonary valve dysplasia is characterized by thickened, nodular, and redundant valvular leaflets with minimal or no commissural fusion; hypoplasia of the valve ring; and lack of poststenotic dilatation of the pulmonary artery.[3, 4] The obstruction is mainly related to thickened, myxomatous, immobile pulmonary valve cusps and hypoplasia of the valve ring.

Changes secondary to pulmonary valve obstruction occur in the right ventricle and pulmonary artery.[1, 2] Hypertrophy of the right ventricular muscle is proportional to the degree (and perhaps the duration) of obstruction. The muscle hypertrophy is particularly prominent in the infundibular region and may become physiologically important; this appears to be related to the degree and duration of obstruction.[5] Mild dilatation of the right ventricular cavity is present. In extremely severe or critical obstruction, the right ventricular cavity may be markedly dilated. In rare cases, the right ventricle may be hypoplastic.

The main pulmonary artery is dilated in almost all cases. This dilatation is independent of the severity of the pulmonary valve obstruction and presumably related to a high-velocity jet across the stenotic valve.[6, 7] As noted above, such poststenotic dilatation is remarkably absent in patients with dysplastic pulmonary valves.

An interatrial communication, a patent foramen ovale or an atrial septal defect may be present and may be the seat for right-to-left shunt in patients with severe or long-standing pulmonary stenosis.

Pulmonary valve stenosis is the most common cardiac lesion in Noonan syndrome (phenotypically Turner syndrome and genotypically normal [XX or XY]).[8, 9]

Supravalvar pulmonary stenosis is often associated with rubella syndrome and Williams syndrome (ie, elfin facies, supravalvar aortic stenosis, and hypercalcemia with or without mental retardation).

Isolated infundibular or subvalvar pulmonary stenosis is uncommon and usually associated with a ventricular septal defect (VSD), such as in tetralogy of Fallot.

Peripheral pulmonary stenosis is frequently observed in newborns. It is related to relative narrowing of the branch pulmonary arteries and the acute angle of the origin of the branch pulmonary arteries at this age. This represents fetal pattern and, in most cases, resolves over time.

Pathophysiology

Clinically significant narrowing of a valve or a blood vessel increases pressure proximal to the obstruction. This pressure gradient is necessary to maintain flow across the stenotic site. In pulmonic stenosis, hypertrophy of the right ventricle ensues and maintains this forward flow. The magnitude of right ventricular pressure and the pressure gradient across the pulmonary valve are generally proportional to the degree of obstruction. Under usual circumstances, proportional right ventricular hypertrophy maintains normal pulmonary blood flow. If the normal output is not maintained, right-sided heart failure ensues. This occurs in neonates with critical pulmonary stenosis and in patients with severe obstruction that occurs in childhood or adulthood.

Changes in the geometry of the left ventricle and decreased left ventricular function can also occur.[10, 11] The changes are proportional to the degree of right ventricular hypertrophy; however, they revert to normal after obstruction of the right ventricular outflow tract is relieved.

With increasing right ventricular hypertrophy, right ventricular compliance decreases with a resultant increase in end-diastolic pressure and with prominent a waves in the right atrium. As right atrial pressure rises, a right-to-left shunt may occur if the foramen ovale is patent or if an atrial septal defect is present; this change results in systemic arterial desaturation and clinically discernible cyanosis. This shunting may occur even without measurable elevation of right atrial pressure and is attributable to decreased right ventricular compliance.[12] Such a right-to-left shunt can also occur in patients with an underdeveloped (hypoplastic) right ventricle.[13]

Epidemiology

Frequency

United States

Pulmonary stenosis represents 8-12% of all congenital heart defects in children.[14, 15] In adults, pulmonary stenosis represents approximately 15% of all congenital heart defects.[16, 17, 18] Isolated valvar pulmonary stenosis with an intact ventricular septum is the second most common congenital cardiac defect in children. It may occur in as many as 50% of all patients with congenital heart disease associated with other congenital cardiac lesions.

Race

Racial difference in the prevalence of pulmonary stenosis is unlikely.[20]

Sex

The male-to-female ratio is 1:1.[16]

Age

The patient's age at presentation is related to the severity of the obstruction. If the stenosis is severe, patients may present in the neonatal period or in infancy. Patients with mild obstruction may present in childhood with asymptomatic murmurs.

 

Presentation

History

Most children with pulmonic stenosis, particularly those with trivial and mild pulmonary stenosis, present with asymptomatic cardiac murmurs that are detected during routine examination.

Patients with moderate or severe pulmonary stenosis may have mild exertional dyspnea. Adults may be asymptomatic irrespective of the severity of their obstruction.[16, 20, 21]

Patients with severe or critical obstruction may present with signs of systemic venous congestion, which are usually interpreted as signs of congestive heart failure (CHF). The signs are due to severe right ventricular dysfunction or to cyanosis secondary to a right-to-left shunt across a patent foramen ovale or an atrial septal defect.

Lightheadedness, syncope, and chest pain that resembles angina pectoris are rare, even in patients with severe obstruction.

Of note, many patients with moderate or severe pulmonary stenosis remain asymptomatic.

Physical

Degree of obstruction

Physical findings depend on the degree of obstruction. Most patients with pulmonary stenosis appear healthy and are well developed. Indeed, the chubby and rounded faces, described as moon facies, were initially thought to be characteristic for this anomaly,[15, 17] but this facial appearance is not a helpful diagnostic tool.[22]

Most patients with trivial, mild, or moderate stenosis, and many with severe stenosis, are acyanotic. However, some may have cyanosis secondary to an interatrial right-to-left shunt.

The jugular venous pulse is normal. However, in patients with decreased right ventricular compliance (ie, severe stenosis), a prominent α wave may be visualized in the neck pulsation. Patients may have a concomitant presystolic pulsation in the liver as well.

In patients with trivial or mild obstruction, the right ventricular impulse is normal. When the pulmonary stenosis is moderate to severe, a sustained and forceful right ventricular impulse and a right ventricular heave are felt.

A thrill may be felt in the suprasternal notch and at the left upper sternal border (pulmonic area). The precordial thrill is most likely to be associated with severe obstruction, although no consistent relationship is observed between the thrill and the degree of obstruction.

Upon auscultation, the first heart sound may be normal in intensity or may be loud. The second heart sound is widely split. The width of the split increases with worsening stenosis. The intensity of pulmonary component of the second heart sound may be loud (in mild stenosis) or may be soft, diminished, or absent, depending on the severity of obstruction. A fourth heart sound may be heard at the left lower sternal border in patients with severe obstruction and is usually associated with prominent α wave in the jugular pulse.

An ejection systolic click is heard along the left sternal border and varies with respiration (decreases or disappears during inspiration). With increasing severity, the click comes closer to the first heart sound.

An ejection systolic murmur of grade II/VI to V/VI is best heard at the left upper sternal border with radiation into infraclavicular regions, axillae, or back. The intensity of the murmur is not necessarily related to the severity of pulmonary valve obstruction, but the duration and timing of peaking of the murmur are related to the severity of stenosis.

An early diastolic decrescendo murmur of pulmonary regurgitation is not usually heard in the typical case of pulmonary stenosis. Previous surgical or balloon intervention or valvar calcification may result in such a murmur.

A holosystolic murmur at the left lower sternal border, which indicates tricuspid regurgitation, may be audible in some patients with extremely severe pulmonary stenosis.

Hepatosplenomegaly is not usually present and may develop in cases of CHF.

Peripheral pulmonary stenosis (commonly encountered in the neonate) is usually associated with a grade II/VI ejection systolic murmur that radiates into the posterior lung fields and axillae. The pathology of peripheral pulmonary stenosis is related to branch pulmonary arteries that are relatively small compared with the large main pulmonary artery, as well as to the acute angular takeoff of the branch pulmonary arteries from the main pulmonary artery specific to a neonate's anatomy. This condition and the associated murmur usually resolve spontaneously in the first month of life.

Clinical assessment of severity

The severity of the obstruction of the pulmonary valve can often be estimated by carefully analyzing the ausculatory findings.[23, 24] The timing of the ejection click, the extent of splitting of the second heart sound, the intensity of the pulmonary component of the second sound, the duration of the systolic murmur, and the timing of the peaking of the ejection murmur usually indicate the severity of pulmonary valve stenosi (see the image below).

In valvar pulmonic stenosis, the severity of obstr In valvar pulmonic stenosis, the severity of obstruction may be judged by auscultatory findings. In mild stenosis, the ejection click (EC) is clearly separated from the first heart sound (S1). The murmur starts with the click, peaks in early systole, and ends way before the aortic component of the second heart sound (A2) The pulmonary component of the second heart sound (P2) is normal to increased in intensity. In moderate pulmonic stenosis, the click is closer to the first heart sound, the ejection murmur peaks later in the systole and the murmur reaches the A2, and the second heart sound is widely split with soft pulmonary component. In severe valvar obstruction, the click is either absent or occurs so close to S1 that it cannot be heard separately, and the murmur peaks late in systole and extends beyond the A2. The second heart sound is widely split with an extremely soft or inaudible P2. Reproduced from Rao PS: Evaluation of cardiac murmur in children. Indian J Pediatr 1991 Jul-Aug; 58(4): 471-91.

With trivial and mild cases of pulmonary valve obstruction, the click is clearly separated from the first heart sound. Almost normal splitting of the second heart sound with normal or slightly increased pulmonary component of the second heart sound is heard. An ejection systolic, diamond-shaped murmur that peaks early in systole and that ends much before the aortic component of the second heart sound is appreciated.

Findings in moderate pulmonary valve stenosis include an ejection systolic click that is closer to the first heart sound than it is in mild forms, a widely split second sound with a diminished pulmonary component, and an ejection systolic murmur that peaks in mid-to-late systole and that ends just before the aortic component of the second heart sound.

In severe narrowing of the pulmonary valve, ausculatory features are an ejection systolic click that is absent or that occurs so close to the first heart sound that it becomes inseparable from it, markedly increased splitting with a soft or inaudible pulmonary component of the second heart sound, and a long ejection systolic murmur that peaks late in systole and that extends beyond the aortic component of the second heart sound so that the latter cannot be heard.

The duration and time of peaking of the ejection systolic murmur, and not its intensity, indicate the severity of the pulmonary valve obstruction. The longer the murmur and the later it peaks, the more severe the obstruction. Likewise, the shorter the interval between the first heart sound and ejection click, the wider the splitting of the second heart sound, and the softer the pulmonary component, the more severe the stenosis of the pulmonary valve.

Causes

Pulmonary valve stenosis is primarily due to maldevelopment of the pulmonary valve tissue and the distal portion of the bulbus cordis, which is characterized by fusion of leaflet commissures, resulting in a thickened and domed appearance of the valve.

Although familial forms of pulmonary stenosis are described, it is generally considered to be multifactorial in origin.[25] Rates of recurrence in siblings are on the order of 2-3%.[26, 27] The prevalence of pulmonary stenosis in the offspring of a parent with pulmonary stenosis is 3.6%.

Aberrant flow patterns in utero may also be partly associated with maldevelopment of the pulmonary valve.[28]

 

DDx

Diagnostic Considerations

Important considerations

Exclude associated congenital anomalies and to detect the presence of cyanosis or a ductal-dependent lesion is a major error.

Do not fail to diagnose a serious congenital heart defect, such as tetralogy of Fallot is problematic.

Note the following:

  • Acyanotic patients with tetralogy of Fallot and those with a mild obstruction of the right ventricular outflow tract may have similar presentations and physical findings.

  • Tetralogy of Fallot is a lesion that is surgically correctable and that can be corrected safely, even in the neonatal period.

  • A tet spell, or hypercyanotic spell, is potentially lethal but frequently aborted with simple maneuvers. Such spells and can occur in previously acyanotic patients with tetralogy of Fallot ("pink tets").

  • Echocardiography can reliably confirm the precise diagnosis and help in differentiating valvar pulmonary stenosis from tetralogy of Fallot.

Echocardiography should not be withheld if complex anatomy is suspected.

Complications associated with balloon pulmonary valvuloplasty, such a rupture or perforation of the pulmonary artery or right ventricular outflow tract, are uncommon but can occur. This possibility should be explained to all parents.

Other problems to be considered

Also consider the following conditions in patients with suspected valvar pulmonary stenosis:

  • Complex congenital heart disease associated with findings of pulmonary stenosis

  • Infundibular and/or subpulmonary stenosis

  • Supravalvar pulmonary stenosis

  • Double-chambered right ventricle

  • Syndrome of absent pulmonary valves

Differential Diagnoses

 

Workup

Laboratory Studies

Laboratory evaluation is usually not helpful in pulmonary valve stenosis.

Hemoglobin and hematocrit measurements in patients with cyanosis may be helpful in that they are increased in patients with right-to-left shunt. The degree of polycythemia is proportional to the degree and duration of right to left shunt. Microcytosis and hypochromia suggest iron deficiency and warrant treatment with iron supplement.

Oximetry provides information of potential right-to-left shunting in borderline cyanotic lesions but does not help in identifying the cause of the shunt (pulmonary, interatrial, interventricular, great arterial).

Although arterial blood gas (ABG) analysis is usually not needed, one notable exception is the hyperoxia test in the newborn with cyanosis of undetermined origin.[29, 30]

The fraction of inspired oxygen (FIO2) of 1 (100% oxygen) generally does not increase the partial pressure of oxygen to more than 100 mm Hg in patients with a cyanotic congenital heart defect (right-to-left intracardiac shunt).

Electrocardiography

Electrocardiographic (ECG) findings are usually normal in mild pulmonary stenosis. Right-axis deviation and right ventricular hypertrophy occur in moderate and severe valvar pulmonary stenosis. The degree of right ventricular hypertrophy is well correlated with the severity of pulmonary stenosis.

Some studies demonstrated good correlation between the height of the R wave in lead V1 and right ventricular peak systolic pressure; the height of the R wave in V1 in mm multiplied by 5 is predictive of right ventricular peak systolic pressure. While the electrocardiogram is a useful noninvasive tool in the evaluation of severity of pulmonary stenosis, Doppler echocardiography provides a more direct indication of the severity of obstruction.

Right atrial hypertrophy and right ventricular hypertrophy with strain pattern are observed when pulmonary stenosis is severe.

A superior QRS axis (left-axis deviation) is seen with dysplastic pulmonary valves and Noonan syndrome.

Staging

The severity of pulmonary valve obstruction may be categorized (staged) as follows, based on peak-to-peak catheter-measured pulmonary valvar gradient[42] :

  • Trivial – Gradient of less than 25 mm Hg

  • Mild – Gradient of 25-49 mm Hg

  • Moderate – Gradient of 50-79 mm Hg

  • Severe – Gradient of more than 80 mm Hg

This severity classification is useful in categorizing patients as per the natural history studies and in formulating treatment algorithms.

Chest Radiography

Chest radiographs reveal a prominent main pulmonary artery segment, but the size of the heart is usually normal (see the image below).

Posteroanterior chest roentgenogram in a patient w Posteroanterior chest roentgenogram in a patient with valvar pulmonic stenosis showing normal-sized heart with normal pulmonary vascular markings. Note prominent main pulmonary artery (arrow). Reproduced with permission from Rao PS: Diagnosis and management of acyanotic heart disease: Part I – Obstructive lesions. Indian J Pediatr 2005; 72: 495-502.

Pulmonary vascular markings are usually normal, but they may be decreased in severe pulmonary stenosis with associated right-to-left shunt.

Cardiomegaly with right ventricular and right atrial enlargement may be seen in severe valvar pulmonary stenosis, with or without tricuspid insufficiency.

Echocardiography

The sine qua non of diagnosis is 2-dimensional and Doppler echocardiography. A thickened pulmonary valve with restricted systolic motion (doming) in the parasternal short axis and subcostal views is demonstrated.[31]

Multiple views are used to confirm the absence of coexistent congenital cardiac disease. Dilatation of the main pulmonary artery distal to the stenotic orifice commonly occurs. Markedly thickened, nodular, and immobile pulmonary valve leaflets may be recognized easily and suggest dysplastic pulmonary valves.

The pulmonary valve annulus can also be visualized and measured. Measurements can be compared with normal values to determine if the annulus is hypoplastic. Such measurements are also useful in selecting the diameter of the balloon to be used during balloon valvuloplasty.

Pulsed, continuous-wave (or high-frequency pulsed), and color Doppler evaluation, in conjunction with 2-dimensional echocardiography, is most useful in confirming the clinical diagnosis and in quantitating the degree of obstruction.[32, 33, 34, 35]

Pulsed Doppler interrogation of the right ventricular outflow tract with sample volume moved across the pulmonary valve demonstrates an abrupt increase in peak Doppler flow velocity, which suggests pulmonary valve obstruction. In addition, the flow pattern in the main pulmonary artery is turbulent instead of laminar. Color Doppler imaging also shows smooth, laminar subpulmonary flow (blue) and some flow acceleration (red) immediately beneath the pulmonary valve, with turbulent (mosaic) flow beginning immediately distal to the pulmonary valve leaflets.

Doppler studies can be used to accurately determine the velocity of flow at single or multiple levels, which then can be converted to reproducible pressure gradients by applying the modified Bernoulli equation, as follows: pressure gradient (in millimeters of mercury) = 4 X (velocity in meters/second)2.

The use of several views and measurements increases the accuracy of the predicted gradient of peak systolic pressure.

Doppler study should be performed when the patient is quiet and in a resting state. Young children and patients who are extremely anxious may have to be mildly sedated.

Severe pulmonary stenosis with gradients of more than 50 mm Hg, as diagnosed using a continuous-wave Doppler recording through the pulmonary valve, should be treated with balloon valvuloplasty or surgery. However, Doppler measurements represent peak instantaneous gradients, whereas catheterization gradients are peak-to-peak gradients; recognition of this concept is more important with aortic-valve gradients than with pulmonary-valve gradients. The peak instantaneous gradient was initially thought to reflect the peak-to-peak systolic gradient measured during cardiac catheterization. However, this peak instantaneous gradient overestimates the peak-to-peak gradient, presumably because of a pressure-recovery phenomenon.[36] In the authors' experience, the catheter peak-to-peak gradient is somewhere in between the Doppler peak instantaneous and mean gradients.

Infundibular gradients secondary to severe right ventricular hypertrophy may be present, but these are not usually observed because severe obstruction of the distal pulmonary valve masks infundibular gradients.[37, 38] However, the infundibular gradients do appear after balloon pulmonary valvuloplasty. A triangular pattern of Doppler signal, similar to that described in subaortic obstruction, is characteristic of infundibular obstruction (see the image below).

Doppler flow velocity recordings from the main pul Doppler flow velocity recordings from the main pulmonary artery prior to (left) and 1 day (center) and 10 months (right) after successful balloon pulmonary valvuloplasty. Note that no significant fall in the peak flow velocity is present on the day after balloon procedure, but a characteristic triangular pattern is present, indicative of infundibular obstruction. At 10-month follow-up, the flow velocity decreased, suggesting resolution of infundibular obstruction. Reproduced with permission from Thapar MK: Significance of infundibular obstruction following balloon valvuloplasty for valvar pulmonic stenosis. Am Heart J 1989; Jul; 118(1): 99-103.

Pulmonary insufficiency is easily seen during pulsed, continuous-wave, or color Doppler imaging, but is unlikely to be present without previous surgical or balloon pulmonary valvuloplasty.

Color Doppler and pulsed Doppler interrogation of the atrial septum is useful and may reveal a left-to-right or right-to-left shunt. Because of high sensitivity of color Doppler imaging, contrast echocardiography is not routinely used to document right-to-left shunt.

Most children with pulmonary stenosis do not require evaluation beyond echocardiography.

Computed Tomography Scanning and Magnetic Resonance Imaging

Computed tomography (CT) scanning and magnetic resonance imaging (MRI) may reveal pulmonary valve stenosis, but the state-of-the-art echocardiography and Doppler studies are more useful than CT or MRI in diagnosing and quantitating pulmonary valve obstruction.[1, 39]

Nuclear Studies

Myocardial energy demands and perfusion may be evaluated by performing magnetic resonance spectroscopy and positron emission tomography (PET), respectively. However, the clinical use of these techniques in the management of pulmonic stenosis has not been established.[1, 39]

Cardiac Catheterization and Selective Cineangiography

Catheterization is not indicated in mild pulmonary stenosis but is essential in severe stenosis and is an integral part of balloon pulmonary valvuloplasty.[40] This procedure is used to confirm the diagnosis; to discern the degree of obstruction; to assess the morphology of the right ventricle, pulmonary outflow tract, and pulmonary arteries; and to exclude other associated cardiac abnormalities.

Patients with echocardiographic evidence of clinically significant pulmonary stenosis (50-60 mm Hg) should undergo diagnostic and therapeutic cardiac catheterization with preparation for balloon dilatation of the pulmonary valve.[41]

Oxygen-saturation data usually do not show evidence of left-to-right shunts. A right-to-left shunt across the patent foramen ovale (or an atrial defect) may be present in moderate-to-severe obstruction of the pulmonary valve.

Pressures Measurements

Note the following:

  • Right atrial pressure (particularly a wave) may be increased.

  • Right-ventricular peak systolic pressure is increased; the magnitude of the pressure is proportional to the degree of obstruction.

  • The transpulmonary valve peak-to-peak gradient also indicate the severity of obstruction. A peak-to-peak gradient in excess of 50 mm Hg is usually considered an indication for therapeutic intervention.[41] Some workers use 40 mm Hg as an indication for intervention.

Angiography

Right ventricular angiography usually reveals thickened and domed leaflets of the pulmonary valve (see the image below) with a thin jet of contrast material across the pulmonary valve.

Right ventricular (RV) cineangiogram in lateral vi Right ventricular (RV) cineangiogram in lateral view in a child with valvar pulmonary stenosis demonstrating thickened and domed pulmonary valve leaflets and poststenotic dilatation of the pulmonary artery (PA). Reproduced with permission from Rao PS: Diagnosis and management of acyanotic heart disease: Part I – Obstructive lesions. Indian J Pediatr 2005; 72: 495-502.

Enlargement and hypertrophy of the right ventricle and a dilated main pulmonary artery are also seen.

In patients with severe or long-standing pulmonary valve obstruction, infundibular constriction may be seen.

Additional cineangiograms at other locations are not necessary unless the echocardiographic and hemodynamic data suggest other abnormalities.

 

Treatment

Medical Care

Prehospital care in patients with pulmonary valve stenosis

Collect essential information about vital signs, including the patient's pulse, respiratory rate, work of breathing, and blood pressure (BP) in the upper and lower extremities. Note the presence or absence of cyanosis.

Associated congenital cardiac anomalies should be anticipated until proven otherwise.

If the patient has a known large left-to-right shunt, such as patent ductus arteriosus (PDA) or ventricular septal defect (VSD), and if the patient is in respiratory distress, diuresis should be attempted. Diuresis is effective in reducing the cyanosis secondary to pulmonary edema, which is unusual in patients with isolated pulmonary valve stenosis.

Use of oxygen may reduce pulmonary artery pressure in patients with a reactive pulmonary vasculature, increasing pulmonary blood flow, which is also unusual in patients with isolated pulmonary valve stenosis.

Administer oxygen to any patient with cyanosis and respiratory distress. However, cyanosis-related intracardiac right-to-left shunting does not resolve hypoxemia.

Emergency department care

Limited diagnostic tests are needed after the structural diagnosis is made. Workup performed for the cyanotic infant with respiratory distress and hypotension or shock is often the same as that performed in a septic patient.

If a neonate or young infant presents to the emergency room with severe cyanosis, ductal dependent lesions should be considered. Prostaglandin infusion may open the ductus, augment pulmonary blood flow, and improve oxygen saturation.

Therapeutic approach

Patients with trivial (gradient < 25 mm Hg) or mild (gradient < 50 mm Hg) pulmonary stenosis do not need intervention to relieve the obstruction of the pulmonary valve.[43] They should be clinically followed up at periodic intervals, perhaps on a yearly basis. During the period of rapid growth (infancy and adolescence), follow-up more frequent than this may be indicated. Routine well-child care, including immunizations by the primary physician, should be provided. Patients with pulmonary stenosis are candidates for infective endocarditis prophylaxis before they undergo any bacteremia -producing procedures and surgery, as indicated in the recommendations of the American Heart Association. Limitations in exercise or activity levels are not needed.

Patients with moderate (gradient, 50-79 mm Hg) and severe (gradient, >80 mm Hg) obstruction should undergo intervention to relieve the stenosis of the pulmonary valve. After the obstruction is relieved, recommended routine care, endocarditis prophylaxis, and exercise limitations are the same as those described for trivial and mild stenosis.

Patients with signs of right ventricular failure should be promptly treated with anticongestive measures, including digitalis and diuretics. However, the problem does not resolve until the obstruction is relieved. Therefore, prompt balloon or surgical intervention should be undertaken. Right ventricular function may not recover completely if intervention is withheld for too long and if myocardial damage sets in.

A fetus with critical pulmonary stenosis or atresia with intact ventricular septum may benefit from pulmonary balloon valvuloplasty in utero, which promotes growth of the right ventricle.[44, 45]

Although the consensus is to offer relief of pulmonary valve obstruction in children with moderate or severe stenoses, this approach is somewhat controversial in adults because of reported lack of progression and the lack of complications in 1 group of adults monitored for 5-24 years in the 1970s.[16] However, a prudent strategy may be to relieve pulmonary valve obstruction in adults with moderate-to-severe pulmonary stenosis, irrespective of their symptoms, because of the potential (1) for myocardial damage associated with long-term pressure overload of the right ventricle,[46] (2) for generally lowered cardiac indices both before and after exercise in adults compared with children,[47] and (3) for exercise-induced hemodynamic abnormalities in adults.[47]

Surgical Care

Balloon pulmonary valvuloplasty

Rubio-Alverez et al first attempted to relieve pulmonary valve obstruction with transcatheter methods in the early 1950s.[48] They used a ureteral catheter with a wire to cut open the stenotic pulmonary valve.

In 1979, Semb et al used a balloon-tipped angiographic (Berman) catheter to rupture pulmonary valve commissures by rapidly withdrawing the inflated balloon across the valve.[49]

More recently, Kan et al[50] applied the techniques of Dotter and Judkins[51] and Gruntzig et al[52] to relieve pulmonary valve obstruction by using the radial forces of balloon inflation of a balloon catheter positioned across the pulmonic valve. This static balloon-dilation technique is currently performed worldwide to relieve pulmonary valve obstruction.

The general consensus based on current data is that balloon valvuloplasty is the treatment of choice for managing isolated pulmonary valve stenosis.[53, 54]

Indications

In general, indications for balloon pulmonary valvuloplasty are similar to those used in surgical pulmonary valvotomy (ie, moderate pulmonary valve stenosis with a peak-to-peak gradient >50 mm Hg with a normal cardiac index). Some cardiologists change this criterion to a gradient of 40 mm Hg or right ventricular pressure of 50 mm Hg. Careful evaluation of the available data suggests that (1) right ventricular pressure is only marginally reduced if mildly stenotic valves are dilated,[41] (2) trivial and mild stenoses (gradient < 50 mm Hg) are likely to remain mild at follow-up (as shown in natural-history studies),[42, 55] and (3) an increase in gradient is easily quantitated on follow-up Doppler echocardiography.[32, 32, 33, 34] If an increased gradient is documented, the patient can then undergo balloon dilatation. Given these observations, balloon dilation should be performed only in patients with peak-to-peak gradient of more than 50 mm Hg.

More recently, the interventional procedures are increasingly performed under general anesthesia and the gradients are usually lower with general anesthesia than with conscious sedation. Consequently, the same criteria should not be applied. Therefore, the Doppler gradients (discussed in Echocardiography) should be used in making the decision regarding balloon pulmonary valvuloplasty.

Technique

The technique of balloon pulmonary valvuloplasty involves positioning a balloon catheter (see the image below) across the stenotic valve, usually over an extra-stiff exchange-length guide wire and inflating the balloon with diluted contrast material to accomplish valvotomy.[56, 57]

Selected cineradiographic frames of a balloon dila Selected cineradiographic frames of a balloon dilatation catheter placed across a stenotic pulmonary valve. Note "waisting" of the balloon during the initial phases of the balloon inflation (A), which was almost completely abolished during the later phases of balloon inflation (B). Reproduced from Rao PS: Balloon pulmonary valvuloplasty for isolated pulmonic stenosis. In: Rao PS, ed: Transcatheter Therapy in Pediatric Cardiology New York, NY: Wiley-Liss; 1993: 59-104.

The initially recommended balloon-to-annulus ratio was 1.2-1.4[55, 58, 59] ; subsequent data suggested a ratio of 1.2-1.25.[60, 61] When the pulmonary valve annulus is too large to dilate with a single balloon (about 20 mm), valvuloplasty with simultaneous inflation of 2 balloons across the pulmonary valve may be performed,[62, 63] although the current availability of large-diameter balloons make this technique unnecessary. However, the double balloon technique may be more effective and stable in some cases. The Inoue balloon has been used in adults with success.[64] The major advantage of the Inoue balloon over conventional balloons is its adjustable diameter that makes stepwise dilation possible. Nucleus balloons with a waist in the middle have been approved by FDA. They do have theoretical advantage; however, these balloons require large sheaths and not a lot of clinical experience has been accumulated so far.

The results of balloon pulmonary valvuloplasty for patients with dysplastic pulmonary valves are generally poor with the use of conventional balloon pulmonary valvuloplasty techniques. Use of large balloons, up to 150% of pulmonary valve annulus,[65] or high-pressure balloons[66] may increase the effectiveness of balloon therapy and avoid the need for surgery.

Mechanism of valvuloplasty

Inflation of a balloon placed across an obstructive lesion exerts radial forces on the stenotic lesion without any axial component.[67, 68]

The mechanism of valvuloplasty is assessed by directly visualizing the valvar mechanism during surgery[69] and postmortem examination[70] and by indirect means, such as angiography and echocardiography.[71, 72] Splitting of the valve commissures and tearing and avulsion of the valve leaflets have been observed and are conceivably the mechanism by which balloon dilation relieves pulmonary valve obstruction. The circumferential dilating force that balloon inflation exerts is likely to rupture (tear) the weakest part of the valve mechanism. The fused commissures are the likely weakest links that can be broken with balloon dilation. However, when fused commissures are strong and cannot be torn, the valve cusps can be torn or the valve leaflet avulse. These events are likely to worsen pulmonary insufficiency.

Pulmonary valve dysplasia, if severe, may preclude successful balloon valvuloplasty unless an associated commissural fusion is present.[65, 73]

Immediate results

Results observed immediately after balloon valvuloplasty include reduced peak-to-peak gradients and right ventricular–to–left ventricular pressure ratios and increased pulmonary artery pressures, jet widths, and free motion of the pulmonary valve leaflets with decreased doming.[53, 54, 74, 75, 76] Improvement of right ventricular function, tricuspid insufficiency,[53] and right-to-left shunt,[12] if present before dilation, are also documented.

Infundibular stenosis

Infundibular gradients occur in nearly 30% patients.[12, 77] The older the patient's age and the greater the severity of obstruction, the greater the prevalence of infundibular reaction. When residual infundibular gradient is >50 mm Hg beta-blockade is generally recommended. Infundibular obstruction greatly regresses at follow-up (see the image below),[5] as demonstrated for infundibular reactions after surgical valvotomy.[78, 79, 80] Rare patients require surgical intervention.

Selected frames from lateral view of the right ven Selected frames from lateral view of the right ventricular (RV) cineangiogram showing severe infundibular stenosis (A) immediately following balloon valvuloplasty (corresponding Media file 3, center). At 10 months after balloon valvuloplasty, the right ventricular outflow tract (B) is wide open and corresponds to Media file 3, right. Peak-to-peak pulmonary valve gradient was 20 mm Hg and no infundibular gradient was present. PA = Pulmonary artery. Reproduced with permission from Thapar MK: Significance of infundibular obstruction following balloon valvuloplasty for valvar pulmonic stenosis. Am Heart J 1989; Jul; 118(1): 99-103.

Follow-up evaluation

Clinical, ECG, and Doppler echocardiographic evaluations are generally recommended at 1 month, 6 months, and 12 months after the procedure and yearly thereafter.[53, 54, 74, 81] Regression of right ventricular hypertrophy, as shown on ECG after balloon dilatation, is well documented. ECG is a useful adjunct in the evaluation of follow-up results.[82] However, ECG evidence of hemodynamic improvement does not become apparent until 6 months after valvuloplasty.[82] The Doppler gradient generally reflects residual obstruction and is a useful and reliable noninvasive monitoring tool.[53, 74, 75, 83]

Intermediate-term results

At intermediate-term follow-up (usually < 2 y), both catheterization-measured peak-to-peak and Doppler-measured peak instantaneous gradients remain improved as a whole.[53, 54, 74] However, restenosis (gradient >50 mm Hg) is observed in nearly 10% patients.[84]

Predictors of restenosis include a balloon-to-annulus ratio of less than 1.2 and a gradient of more than 30 mm Hg immediately after valvuloplasty. In addition, early in the study period, a small valve annulus, and a postsurgical or complex pulmonary stenosis were also predictive of restenosis.[85]

Patients with restenosis have been successfully treated with redilatation with balloons larger than those used for initial balloon valvuloplasty.[86] Redilatation is the procedure of choice for managing restenosis after previous balloon dilatation. However, if the pulmonary valve annulus is hypoplastic, if the pulmonary valve leaflets are dysplastic, or if clinically significant supravalvar pulmonary artery stenosis is the major reason for the restenosis, surgery is recommended.

Long-term follow-up results

Although immediate and short-term results have been documented,[76, 81] data on long-term results are scarce. Published studies reveal generally low residual peak instantaneous Doppler gradients with minimal (1-2%) late recurrence of pulmonary stenosis (beyond that seen at intermediate follow-up).[59, 76]

In one study, approximately 5% of patients needed surgical intervention to relieve fixed subvalvar or supravalvar stenosis.[76] Actuarial freedom for reintervention was 88% and 84%, respectively, at 5 and 10 years. Pulmonary valve insufficiency was noted in 80-90% patients, but right ventricular volume overloading did not develop, and none of the patients required surgical intervention because of pulmonary insufficiency. Based on these data, the authors concluded that balloon pulmonary valvuloplasty may continue to be the treatment of choice for moderate-to-severe valvar pulmonary stenosis, and 10-year to 20-year follow-up studies to evaluate the clinical significance of residual pulmonary insufficiency should be undertaken.

Clinically significant pulmonary insufficiency

One report documented the development of clinically significant pulmonary insufficiency in 6 (6%) of 107 patients at late follow-up. Some of these patients required pulmonary valve replacement.[60] In a recent report, 53 patients with pulmonary valve stenosis who had percutaneous balloon valvuloplasty were followed for 10-24 years (median, 15 years); there was only 2% prevalence of restenosis, but late pulmonary regurgitation developed in 89% patients.[87]

Comparison with surgical valvotomy

Comparison of balloon therapy with surgical valvotomy has limitations,[53, 76] but the mortality and morbidity rates are generally higher after surgery. Greater reduction of the gradient is observed after surgery, but the degree and frequency of pulmonary insufficiency may be higher after surgery than after balloon therapy.[88, 89]

Critical pulmonary stenosis in the neonate

The term critical pulmonary stenosis with intact ventricular septum is applied to severe pulmonary valvar obstruction resulting in suprasystemic right ventricular systolic pressure with resultant tricuspid insufficiency, a right-to-left shunt across the atrial septum, and often a ductal-dependent pulmonary circulation.

Although the surgical approach to relieve the obstruction with or without aorta-pulmonary shunt was standard treatment in the past, transcatheter treatment is now first-line therapy.

Prostaglandin E1 is infused to augment pulmonary blood flow and improve systemic arterial desaturation, followed by cardiac catheterization and biplane (sitting-up and lateral views) right ventricular cineangiography. A right coronary artery, angled glide, balloon wedge, or cobra catheter (according to the operator's preference) is placed in the right ventricular outflow tract, and a floppy-tipped coronary guidewire is advanced across the pulmonary valve and into the right or left pulmonary artery or into the descending aorta through the ductus. The catheter is advanced across the pulmonary valve into a distal pulmonary artery or the descending aorta. The guidewire is then exchanged for a guidewire that is suited to position the balloon-dilation catheter. Then, balloon pulmonary valvuloplasty is performed in manner described earlier.[90, 91]

In some cases, the balloon catheter cannot be advanced across a severely stenotic pulmonary valve, and balloon catheters 3-6 mm in diameter may be used for initial predilation and then replaced with larger, more appropriately sized balloon catheters.

Although the results of this approach are reasonably good, the need for reintervention to address the complications associated with the procedure, residual obstruction, or associated defects is 25% in neonates compared with older children 8-10%.[90, 91, 92]

Other catheter interventions

Numerous other catheter interventions may become necessary in patients with pulmonary stenosis.

Transcatheter occlusion of a patent ductus arteriosus (PDA)

Some patients with pulmonary stenosis may have a PDA of significant size. In such patients, transcatheter occlusion of the PDA performed with a coil (for small PDAs) or with an Amplatzer duct occluder (for medium or large PDAs) is recommended immediately after balloon pulmonary valvuloplasty. (See also the article Patent Ductus Arteriosus.)

Occlusion of a patent foramen ovale or atrial septal defect

A patent foramen ovale or atrial septal defect may occur in association with pulmonary stenosis. If these atrial defects do not spontaneously close during follow-up after balloon valvuloplasty, they may be closed with an Amplatzer septal occluder or Helex device, if the criteria for their closure are met. Sometimes, the defects may need to be closed to prevent recurrent paradoxical embolisms. (See also the article Atrial Septal Defect, General Concepts.)

Balloon atrial septostomy[52]

In neonates with a severely hypoplastic right ventricle, balloon atrial septostomy may be necessary to provide adequate egress to the systemic venous return. Indications are clinical signs of systemic venous congestion, restrictive patent foramen ovale on Doppler echocardiography, markedly elevated right atrial pressure with tall a waves, and/or a mean atrial pressure difference of more than 5 mm Hg.

In neonates, Rashkind balloon septostomy is effective. Beyond the neonatal period, Park blade septostomy or surgical septostomy may be necessary. In patients with only mild or moderate right ventricular hypoplasia, balloon septostomy should be avoided so that forward flow through the right ventricle is encouraged with a consequent opportunity for its growth.

Cardiac catheterization with balloon valvuloplasty

This is the preferred therapy for severe or critical valvar pulmonary stenosis. In neonates with critical valvar pulmonary stenosis, mortality rates related to balloon dilation are lower than those related to surgery mortality, and balloon dilation is the treatment of choice.

Other surgical techniques

Since the first description of surgical relief of pulmonary stenosis by closed pulmonary valvotomy in the late 1940s,[93, 94] various techniques were developed and include valvotomy with inflow occlusion, hypothermia and cardiopulmonary bypass. The currently preferred approach is transpulmonary arterial valvotomy under cardiopulmonary bypass.[95]

Results

Results of surgery are generally good with low mortality rate (3-7%) and decreased right ventricular pressures and pulmonary valve gradients. In a natural-history study in the United States, only 3% of 294 operated patients had gradients of more than 50 mm Hg at 4-8 years after surgery.[42] The incidence of pulmonary insufficiency at follow-up was 60-90%.[96] Despite these good results, transluminal balloon pulmonary valvuloplasty (discussed above) has replaced surgical pulmonary valvotomy.

Indications

Surgery is reserved for cases in which balloon valvuloplasty is not feasible or not successful. One example is dysplastic pulmonary valve with valve ring hypoplasia. The treatment of this disorder is to excise the obstructive valve leaflets and enlarge the annulus by a transannular patch. Other examples are fixed infundibular and supravalvar stenosis after successful balloon valvuloplasty.[76]

Blalock-Taussig shunt

Patients with critical pulmonary stenosis and marked hypoplasia of the right ventricle may need a Blalock-Taussig shunt in addition to or instead of balloon or surgical valvotomy.

Right ventricular repair/bypass

Right ventricular hypoplasia, as alluded to above, occurs in some patients with pulmonary stenosis, although this hypoplasia is most common in patients with pulmonary atresia and an intact ventricular septum. The right ventricle may enlarge after right ventricular outflow obstruction is relieved, particularly in tripartite right ventricles.[97, 98, 99]

If the right ventricle does not grow adequately to support the pulmonary circulation, 1.5 or single ventricular repair should be considered. In 1.5-ventricular repair, a bidirectional Glenn procedure (superior vena cava–to–right pulmonary artery anastomosis, end to side) is performed to divert the blood from the upper part of the body directly into the pulmonary artery, and the atrial septal defect is closed to allow the blood from the lower part of the body to go into the lungs through the right ventricle. In the single ventricle repair, the right ventricle is bypassed by the Fontan procedure. In the Fontan procedure, staged total cavopulmonary connection is performed by bidirectional Glenn initially and then extra conduit diversion of the inferior cava into the pulmonary artery.

See the article Tricuspid Atresia.

Consultations

Consultation with a pediatric cardiologist precedes consultation with a cardiothoracic surgeon.

Patients with pulmonary valve atresia or a critical pulmonary stenosis with an inadequate right ventricle require a shunt (usually a modified Blalock-Taussig or central shunt) after the ductus arteriosus is pharmacologically kept patent with prostaglandin E1.

Definitive repair may not be possible if the right ventricle is hypoplastic. Single ventricular palliation, such as the Fontan procedure, or variation, such as staged total cavopulmonary connection, may be required.

Activity

A prudent philosophy is to allow patients to limit their own activity according to personal tolerance.

Restriction from highly exertional and competitive sports is recommended only for patients with severe pulmonary stenosis.

After successful relief of the obstruction, normal activity may be resumed.

 

Medication

Medication Summary

No medications are useful in isolated valvar pulmonary stenosis. Patients with congestive heart failure (CHF) may benefit from anticongestive therapy. Patients with cyanosis may benefit from oxygen and prostaglandin E1. Patients with cyanosis due to a large right-to-left shunt require a definitive surgical procedure.

Patients with certain cardiac conditions, such as pulmonary stenosis, typically require antibiotic prophylaxis for endocarditis before they undergo procedures that may cause bacteremia. For more information, see Antibiotic Prophylactic Regimens for Endocarditis.

Prostaglandins

Class Summary

Alprostadil (Prostaglandin E1, PGE1) is used to treat ductal-dependent cyanotic congenital heart disease, which is caused by decreased pulmonary blood flow. Alprostadil acts as a smooth muscle relaxer and maintains patency of the ductus arteriosus when a cyanotic lesion (eg, critical pulmonary stenosis or atresia) or when an interrupted aortic arch occurs in a newborn. This drug is effective only in the neonatal period.

Alprostadil IV (Prostin VR)

First-line drug used as palliative therapy to temporarily maintain patency of ductus arteriosus before surgery. Produces vasodilation and increases cardiac output. Also inhibits platelet aggregation and stimulates intestinal and uterine smooth muscle.

Used in suspected critical pulmonary stenosis when presentation includes cyanosis. Also used in ductal-dependent lesion (eg, pulmonary atresia variants, coarctation of aorta, interrupted aortic arch). Each 1-mL ampule contains 500 mcg/mL.

Beta-blockers

Class Summary

These drugs inhibit chronotropic, inotropic, and vasodilatory responses to beta-adrenergic stimulation.

Atenolol (Tenormin)

Used to treat hypertension. Selectively blocks beta1-receptors with little or no affect on beta2 types. Beta-blockers affect BP by several mechanisms, including negative chronotropic effect that decreases heart rate at rest and after exercise, negative inotropic effect that decreases cardiac output, reduction of sympathetic outflow from the CNS, and suppression of renin release from the kidneys. Used to improve and preserve hemodynamic status by acting on myocardial contractility to reduce congestion and decrease myocardial energy expenditure.

Beta-blockers reduce inotropic state of left ventricle, improve diastolic function, and increase LV compliance, reducing pressure gradient across LV outflow tract. Decreases myocardial oxygen consumption, reducing myocardial ischemia potential. Decreases heart rate, reducing myocardial oxygen consumption and reducing potential for myocardial ischemia. During IV administration, carefully monitor BP, heart rate, and ECG.

The drug may be used to reduce hypercontractility of the right ventricle in patients with significant infundibular stenosis (gradients >50 mm Hg) following balloon pulmonary valvuloplasty.

Esmolol (Brevibloc)

Ultra–short-acting that selectively blocks beta1-receptors with little or no effect on beta2-receptors. Particularly useful in elevated arterial pressure, especially if surgery planned. Reduced episodes of chest pain and clinical cardiac events compared with placebo. Can discontinue abruptly if necessary. Useful in patients at risk for complications from beta-blockade, particularly those with reactive airway disease, mild-to-moderate LV dysfunction, and/or peripheral vascular disease. Short half-life of 8 min allows for titration to desired effect and quick discontinuation if needed.

Propranolol (Inderal)

Nonselective beta-blocker. Lipophilic (penetrates CNS). Has membrane-stabilizing activity and decreases automaticity of contractions. Also has class II antiarrhythmic properties.

 

Follow-up

Further Outpatient Care

Clinical, ECG, and Doppler echocardiographic evaluation are recommended at 1 month, 6 months, and 12 months after balloon pulmonary valvuloplasty and yearly thereafter.

Patients with trivial and mild pulmonary stenosis do not need intervention to relieve the pulmonary valve obstruction. However, they should be clinically followed up at periodic intervals (eg, on a yearly basis).

Routine well-child care, including immunizations, as per the primary physician, is suggested.

Physical activity should be normal.

Most patients with pulmonary stenosis are given prophylaxis for subacute bacterial endocarditis (SBE).

Opinions differ about the need for SBE prophylaxis in patients with valvar pulmonary stenosis because of the extremely low incidence of pulmonary valve endocarditis in this relatively large subpopulation. The author recommends SBE prophylaxis for all patients with valvar pulmonary stenosis.

Further Inpatient Care

The neonate with critical pulmonary valve stenosis requires special consideration. Patients with critical pulmonary stenosis may present with near–pulmonary atresia (cyanotic lesion) with a small and often inadequate right ventricle. These patients survive because of a patent ductus arteriosus (PDA). Although balloon pulmonary valvuloplasty produces good results, nearly 25% patients require reintervention to address related complications, restenosis, and associated defects.

Patients with associated severe infundibular or supravalvar pulmonary stenosis require surgical intervention.

Definitive repair may not be possible if the right ventricle is hypoplastic or if single ventricular palliation (eg, the Fontan procedure or a variation of this) is needed. The modified Fontan procedure currently used is staged cavopulmonary connection.

Patient Education

Reassure patients and parents of children with mild valvar pulmonary stenosis that this condition is not related to or associated with coronary artery disease, dysrhythmia, or sudden death.

Insurability may become a factor in obtaining further care. Patients are no more at risk for disastrous health consequences than is the usual population.

Provided the patient is asymptomatic and acyanotic and provided that initial Doppler echocardiograms show only mild valvar pulmonary stenosis, yearly screening examination and ECG are prudent follow-up care.

If evaluations performed a few years after the initial evaluation reveal no clinically significant change, the patient may be followed up once every 3-5 years.

For patient education resources, see the Heart Health Center, as well as Tetralogy of Fallot.