Introduction
Background
The term pulmonic stenosis (PS, pulmonary stenosis, pulmonary valve stenosis) is used to refer to the 2 types of right ventricular outflow obstruction — namely, valvular stenosis and infundibular stenosis. Valvular pulmonary stenosis commonly occurs as an isolated lesion. Occasionally, supravalvular stenosis may occur.
The most common cause of valvular PS is congenital. Rheumatic inflammation of the pulmonic valve is uncommon. Rheumatic pulmonary valve disease usually involves other valves; it rarely leads to serious pulmonic valvular deformity. One study from New Mexico reported a high incidence of significant pulmonic valve involvement secondary to rheumatic fever. Such involvement may occur in association with the pulmonary hypertension that occurs at high altitudes and the increase in stress that such hypertension places on the pulmonic valve.
In patients with malignant carcinoid, carcinoid plaques, not unlike those affecting the tricuspid valve, may involve the outflow tract of the right ventricle. The plaques result in constriction of the pulmonic valve ring, retraction and fusion of the valve cusps, and either PS or the combination of PS and pulmonic regurgitation. Obstruction in the region of the pulmonic valve may be extrinsic to the valve apparatus and may be produced by cardiac tumors or by aneurysm of the sinus of Valsalva.
Congenital PS is usually treated by balloon dilation; it sometimes requires surgical valvotomy. If there is severe hypoxia (PaO2 <30 mm Hg), then it may be necessary to create a systemic-to-pulmonary shunt; prostaglandin may be required to maintain patent ductus.1,2,3,4
Pathophysiology
Valvular pulmonic stenosis is the most common form of isolated right ventricular obstruction; it occurs in about 7% of patients with congenital heart disease. The pulmonic valve lesion is often accompanied by hypertrophy of the septal and parietal bands, with narrowing of the right ventricular infundibulum; such hypertrophy is especially prevalent in severe cases of PS. In the severest forms, fused cusps of varying thickness and rigidity form a fibrous dome.
Pulmonic stenosis (PS, pulmonary stenosis, pulmonary valve stenosis) typically occurs in the fetal heart during the first 8 weeks of pregnancy.
Pulmonic valve dysplasia, which is especially common in patients with Noonan syndrome, produces obstruction in the absence of adherent leaflets. The leaflets are thickened, rigid, and myxomatous; and they are restricted in their lateral movement by tissue pads within the pulmonic valve sinuses.
In valvular PS, the pulmonary valve leaflets are thickened and domed during systole; the configuration returns to normal during diastole. Poststenotic dilatation of the main pulmonary trunk and sometimes of the left pulmonary artery is usual.
In dysplastic PS, the leaflets of the dysplastic pulmonic valve are not fused anatomically; rather, they are thickened and immobile; thus, on angiography, the appearance of the valve changes little during the cardiac cycle. A small annulus and narrow sinuses of Valsalva commonly accompany valve dysplasia.
With either type of valve, systolic narrowing of the right ventricular infundibulum usually is associated with moderate or severe obstruction.5,6
Frequency
United States
Valvular pulmonic stenosis results from fusion of the valve cusps during mid to late intrauterine development. This is the most common form of isolated right ventricular obstruction; it occurs in about 7% of patients with congenital heart disease.
International
Internationally, the incidence of pulmonic stenosis is the same as that in the United States.
Mortality/Morbidity
- Neonates and children: The clinical presentation and course of circulation in a newborn with pulmonic stenosis are determined by the severity of obstruction and by the degree of development of the following structures: the right ventricle and its outflow tract; the tricuspid valve; and the pulmonary arterial tree (see Clinical Details).
- Children: The clinical profile of children with valvular PS (other than infants) usually is distinctive. The severity of obstruction is the most important determinant of the clinical course (see Clinical Details).
- Cases of mild or moderate pulmonic valve stenosis generally follow a favorable course; uncommonly, the obstruction becomes more severe, particularly during infancy (see Clinical Details).
Race
No particular racial predilection has been reported for pulmonic stenosis.
Sex
No clear sex dominance has been described for pulmonic stenosis.
Age
If not detected at birth, pulmonic stenosis is usually diagnosed by 3 years of age; patients present with dyspnea and fatigue.
Anatomy
Valvular pulmonic stenosis, which results from fusion of the valve cusps during mid to late intrauterine development, is the most common form of isolated right ventricular obstruction; it occurs in about 7% of patients with congenital heart disease.
Hypertrophy of the septal and parietal bands, with narrowing the right ventricular infundibulum, often accompanies the pulmonic valve lesion, especially if it is severe.
In the severest cases, fused cusps of varying thickness and rigidity form a fibrous dome.
Pulmonic valve dysplasia is especially common in patients with Noonan syndrome. Although the leaflets are not adherent, obstruction occurs nevertheless, owing to the fact that the leaflets are thickened, rigid, and myxomatous and that their lateral movement is limited by tissue pads within the pulmonic valve sinuses.
Presentation
Natural history
Mild and moderate valvular pulmonic stenoses (PS, pulmonary stenosis, pulmonary valve stenosis) have a generally favorable course. Although severe PS may lead to right heart failure, arrhythmias, and early death, most children with repaired pulmonary valves or mild to moderate disease lead full, healthy lives. In some patients with mild PS, the disease may progress, and the patient will require intervention later; other patients do well and never require intervention.
In serial hemodynamic studies conducted over 4- to 8-year intervals, pressure gradients remained unchanged in three fourths of patients. Of the remaining patients, equal percentages experienced increased or decreased obstruction. Significant increases in the pressure gradient may occur, especially in children with a gradient in excess of 50 mm Hg at initial examination.7
General physical examination findings
The physical findings often suggest the severity of obstruction.
Right ventricular hypertrophy reduces compliance of that chamber, and a forceful right atrial contraction is necessary to augment right ventricular filling.
Prominent a waves in the jugular venous pulse, a fourth heart sound, and, occasionally, presystolic pulsations of the liver reflect vigorous atrial contraction and suggest the presence of severe stenosis.
Cardiomegaly and a right ventricular parasternal lift accompany moderate or severe obstruction.
A systolic thrill is palpable along the upper left sternal border in all but the mildest forms of stenosis. The first heart sound is normal; it is followed by a systolic ejection sound at the upper left sternal edge, which is produced by sudden opening of the stenotic valve. An ejection sound is not heard in patients with pulmonic valve dysplasia. The ejection sound typically is louder during expiration; when it is inaudible or occurs less than 0.08 seconds after the onset of the Q wave on ECG, severe obstruction is suggested.
The right ventricular ejection is prolonged in patients with moderate or severe stenosis; in such patients, the sound of pulmonic valve closure is delayed and soft.
On auscultation, the characteristic feature of valvular PS is a harsh, diamond-shaped systolic ejection murmur heard best at the upper left sternal border. With more severe valvular obstruction, the systolic murmur becomes louder, and its crescendo occurs later in systole, such that it obscures the aortic component of the second sound; these signs occur as a result of prolongation of right ventricular systole.
The holosystolic decrescendo murmur of tricuspid regurgitation may accompany severe PS, especially in the presence of congestive heart failure.
Cyanosis, which reflects venoarterial shunting through a patent foramen ovale, is absent in cases of mild stenosis; it is infrequent in cases of moderate obstruction. Cyanosis may not be apparent in patients with severe obstruction if the atrial septum is intact.
Presentation in infants and neonates
The clinical presentation and course of circulation in a newborn with PS depends on the severity of obstruction and on the degree of development of the following structures: the right ventricle and its outflow tract; the tricuspid valve; and the pulmonary arterial tree. The greater the degree of pulmonic valve stenosis, the more closely the manifestations resemble those observed in cases of pulmonary atresia in which the ventricular septum is intact.
Severe PS is characterized by cyanosis; the cyanosis is the result of right-to-left shunting through the foramen ovale, as well as cardiomegaly and diminished pulmonary blood flow in the absence of persistent patency of the ductus arteriosus. Hypoxemia and metabolic acidemia, rather than right ventricular failure, are the main clinical disturbances in symptomatic neonates. These symptoms may be alleviated temporarily with an infusion of prostaglandin E1, which allows the patent ductus arteriosus to be maintained.
Babies with these conditions may usually be distinguished from those with tetralogy of Fallot or tricuspid or pulmonary atresia on the basis of radiographic and ECG evidence. In typical cases of tetralogy, there is no radiographic evidence of cardiomegaly. For infants with tricuspid and pulmonary atresia, ECGs show a preponderance of left ventricular forces, in contrast to the right ventricular hypertrophy usually observed in patients with critical PS who are without right ventricular hypoplasia.
Combined 2-dimensional ECG and continuous-wave Doppler examination may be used to characterize the anatomic valve abnormality and its severity. MRI may be performed in utero; although there are no reports of harm resulting from the use of MRI in utero, there is insufficient date to guarantee that there are no harmful effects. These techniques have essentially eliminated the need for cardiac catheterization and angiographic studies to establish a precise diagnosis.
Presentation in children
In cases of PS in which the cardiac output is normal, PS is considered mild if the valve gradient is less than 25 mm Hg; PS is considered moderate if the gradient is 25-49 mm Hg; PS is considered severe if the gradient is 50-79 mm Hg; PS is considered critical if the gradient is 80 mm Hg or higher.
Most patients with mild PS are asymptomatic; for these patients, the condition is discovered during routine examination. The severity of stenosis may increase with time.
Progression may be relative. Progression may reflect disproportional physical growth of the patient, or it may reflect infundibular narrowing, which occurs as a result of progressive hypertrophy of the right ventricular outflow tract or fibrosis of the valve cusps.
Symptoms, when present, vary from mild exertional dyspnea and mild cyanosis to signs and symptoms of heart failure, depending on the degree of obstruction and the level of myocardial compensation. Exertional fatigue, syncope, and chest pain are related to an inability to augment pulmonary blood flow during exercise in some patients with moderate or severe obstruction.
Preferred Examination
Echocardiography
Reliable localization of the site of obstruction and an assessment of its severity are possible with combined continuous-wave or pulsed-wave Doppler and 2-dimensional echocardiography.
The 2-dimensional echocardiogram usually shows prominent pulmonary valve echoes with restricted systolic motion, as well as poststenotic dilation of the main pulmonary artery and its branches.
Electrocardiography
Electrocardiography (ECG) may be helpful in assessing the degree of obstruction to right ventricular output.
In mild cases, the ECG often appears normal, whereas moderate and severe stenoses are associated with right-axis deviation and right ventricular hypertrophy. In patients with severe stenosis who are 2-20 years of age, right ventricular pressure may be estimated by multiplying the height of the R wave in lead V4R or V1 by 5. A tall QR wave in the right precordial leads with T-wave inversion, together with ST-segment suppression (right ventricular strain), reflects severe stenosis.
When a regular sinus rhythm is observed in lead V1 (20% of patients), right ventricular pressures are lower than those in cases in which there is a pure R wave of equal amplitude. High-amplitude P waves in leads II and V1 indicate right atrial enlargement; such findings are associated with severe stenosis.
Limitations of Techniques
There are very few limitations of these techniques. A good-quality ECG may be unobtainable in obese patients or in patients in whom the acoustic windows are poor.
Differential Diagnoses
Pulmonary Hypertension
Tetralogy of Fallot
Tricuspid Atresia
Tricuspid Valve Disease
More on Pulmonic Stenosis |
 Overview: Pulmonic Stenosis |
| Imaging: Pulmonic Stenosis |
| Follow-up: Pulmonic Stenosis |
| References |
| Further Reading |
| Next Page » |
References
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Latson LA. Critical pulmonary stenosis. J Interv Cardiol. Jun 2001;14(3):345-50. Review.
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Ferrero GB, Baldassarre G, Delmonaco AG, Biamino E, Banaudi E, Carta C, et al. Clinical and molecular characterization of 40 patients with Noonan syndrome. Eur J Med Genet. Jul 17 2008;[Medline].
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Popescu BA, Jurcut R, Serban M, Parascan L, Ginghina C. Shone's syndrome diagnosed with echocardiography and confirmed at pathology. Eur J Echocardiogr. Jul 11 2008;[Medline].
Cotrim C, Miranda R, Loureiro MJ, Almeida S, Lopes L, Almeida AR, et al. Echocardiography during treadmill exercise testing for evaluation of pulmonary artery systolic pressure: advantages of the method. Rev Port Cardiol. Apr 2008;27(4):453-61. [Medline].
Geva T, Greil GF, Marshall AC. Gadolinium-enhanced 3-dimensional magnetic resonance angiography of pulmonary blood supply in patients with complex pulmonary stenosis or atresia: comparison with x-ray angiography. Circulation. Jul 23 2002;106(4):473-8.
Bonhoeffer P, Boudjemline Y, Qureshi SA. Percutaneous insertion of the pulmonary valve. J Am Coll Cardiol. May 15 2002;39(10):1664-9. [Medline].
Carr-White GS, Kilner PJ, Hon JK. Incidence, location, pathology, and significance of pulmonary homograft stenosis after the Ross operation. Circulation. Sep 18 2001;104(12 Suppl 1):I16-20.
Fawzy ME, Awad M, Galal O. Long-term results of pulmonary balloon valvulotomy in adult patients. J Heart Valve Dis. Nov 2001;10(6):812-8. [Medline].
Molina JE, Wang Y, Stillman AE. Right transatrial approach to relieve pulmonary stenosis in patients with corrected transposition of the great vessels: a new operation without use of an extracardiac conduit. J Card Surg. Nov-Dec 2000;15(6):411-7.
Tulzer G, Arzt W, Franklin RC. Fetal pulmonary valvuloplasty for critical pulmonary stenosis or atresia with intact septum. Lancet. Nov 16 2002;360(9345):1567-8.
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Further Reading
Related eMedicine topics
Pulmonary Stenosis, Valvar
Pulmonary Stenosis, Infundibular
Aortic Stenosis
Clinical guidelines
ACC/AHA 2006 guidelines for the management of patients with valvular heart disease. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease).
American College of Cardiology Foundation - Medical Specialty Society
American Heart Association - Professional Association. 1998 Nov 1 (revised 2006). 103 pages. NGC:005067
Guidelines on the management of valvular heart disease.
European Society of Cardiology - Medical Specialty Society. 2007 Jan. 39 pages. NGC:005534
Keywords
pulmonic stenosis, pulmonary valve stenosis, pulmonary stenosis, pulmonary valvular stenosis, PS, right ventricular outflow obstruction, isolated right ventricular obstruction, valvular stenosis, infundibular stenosis, supravalvular stenosis
