AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

First described by Elliotson, infundibular pulmonary stenosis (IPS) refers to obstruction of outflow from the right ventricle (RV) within the body of the RV, as opposed to obstruction at the pulmonary valve, pulmonary artery (PA), or its branches. IPS often occurs in association with other intracardiac anomalies; isolated IPS is rare. In this article, IPS refers to isolated infundibular pulmonary stenosis with an intact ventricular septum.

Pathophysiology

IPS has 2 forms. In the more common type, stenosis of the proximal portion of the infundibulum is due to a fibrous or muscle band at the junction of the main cavity of the RV and the infundibulum. The band divides the cavity into 2 chambers. The second type is associated with a thickened muscular infundibulum that forms a narrow outlet to the RV. The infundibulum appears shrunken. In this second type, the narrowed area may be short or long and may be located immediately below the pulmonary valve or lower into the outflow tract.

IPS is often associated with a ventricular septal defect (VSD). Common opinion holds that the VSD closes, leaving behind an isolated IPS. Whether some children have excessive muscle without ever having had a VSD is not known.

The hemodynamic consequence of the obstruction is elevated pressure within the RV cavity. The degree of elevation depends on the severity of obstruction. When severe, the resulting RV systolic pressure may exceed that of the left ventricle (LV). This high pressure is limited to the portion proximal to the infundibulum. Lower or even normal pressures are present beyond the obstruction site. Reactive RV hypertrophy follows.

Subsequent elevation of end-diastolic pressure and decreased compliance of the RV, consequent to the hypertrophy, lead to elevated right atrial (RA) pressure and dilatation of that chamber. Greater RA pressures are required to fill the ventricle, and relative right and left atrial pressures may be reversed, favoring persistent patency of the foramen ovale and right-to-left shunting. This gives rise to central cyanosis. Such reversal and cyanosis can occur when the RV is hypoplastic, even with less severe PS.

In neonates with severe PS, the pulmonary blood flow depends on the patency of the ductus arteriosus. The RV becomes hypertrophic and maintains cardiac output to a very advanced stage. With exercise, the requirement for cardiac output increases, and RV pressure proportionately rises until it exceeds the capacity of the RV muscle.

Deformity and malfunctioning of the LV occur in proportion to RV hypertension and can be demonstrated using sophisticated techniques. These LV problems have little practical consequence because they improve with relief of the RV hypertension.

Reduced LV end-diastolic compliance has been chiefly ascribed to displacement of the interventricular septum (IVS) into the LV cavity. The mechanisms responsible for systolic dysfunction are less clear.

Patients with isolated valvular PS may have a reactive infundibular hypertrophy that could elicit a reactive infundibular obstruction. This obstruction might persist for a variable period following relief of the valvar obstruction.

IPS can cause anatomic and, possibly, functional changes in the developing pulmonary vascular bed. Experimental construction of the pulmonary trunk in fetal lambs is accompanied by relatively thin-walled PA resistance vessels. Some researchers postulate this decreased medial muscular layer is caused by a higher oxygen tension of the blood perfusing the fetal pulmonary circulation.

IPS has been noted to develop in a fetus following twin-to-twin transfusion, and authors have, in that case, postulated that the elevated blood volume/pressure may be a factor in the pathogenesis.¹ Inversin, the product of the inv locus, may have a specific role in cardiac morphogenesis (especially in the development of IPS) in addition to its contribution to situs determination.

Frequency

United States

The relative frequency of IPS among all obstructive lesions of the RV outflow tract is 2-10%.

International

No reliable figures have been reported.

Mortality/Morbidity

Severe IPS that leads to atresia can result in neonatal death when the ductus arteriosus constricts. Heart failure secondary to IPS is rare in childhood beyond early infancy. Exercise may provoke syncope and even sudden death in severe stenosis. The stenosis may remain asymptomatic but may progress to require intervention in adulthood.

Sex

IPS has no gender predilection.

Age

IPS is present from birth, although most patients are asymptomatic. The severity of stenosis can progress with age.

CLINICAL

Section 3 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

History

Infundibular pulmonary stenosis (IPS) manifestations depend on the severity of obstruction and presence or absence of associated cardiac anomalies.

• Most children grow well and are asymptomatic, even when stenosis is moderate or severe.
• The murmur is discovered on routine auscultation, usually at birth, although cyanosis may lead to discovery of maximum obstruction.
• Symptoms are rare in infants, with the notable exception of patients with critical stenosis.
• Subjective complaints tend to increase with age.
• Dyspnea and fatigue are the most common symptoms.
• Exertion may provoke syncope or even death.
• Precordial pain is common, and epigastric pain is often present.
• Frank right-sided heart failure occasionally occurs in infancy or early childhood.
• Squatting is extremely rare in children with isolated PS (compared with tetralogy of Fallot)

Physical

• Growth and development are usually normal. Frank heart failure is rarely evident.
• Chest asymmetry occasionally accompanies severe stenosis, but precordial bulge is uncommon.
• Jugular venous pulse shows larger a waves as the degree of obstruction increases. These presystolic pulsations may be felt during palpation of the liver, even without evidence of cardiac failure.
• Prominent left parasternal heave occurs if PS is significant.
• A systolic thrill is present at the second and third left intercostal space near the sternum. Occasionally, the thrill may disappear with onset of failure.
• The first heart sound is normal.
• The pulmonic valve component (P-2) of the second heart sound is soft and delayed in moderate-to-severe stenosis.
• • The degree of split is proportionate to the severity of the obstruction; the greater the obstruction, the longer the RV takes to empty and the wider the split.
  • P-2 decreases in intensity in proportion to the pressure in the PA. The lower the pressure, the softer the P-2. P-2 may be inaudible with maximal obstruction.
  • In severe stenosis with unchanging cardiac output, the split may be fixed. A loud pansystolic crescendo-decrescendo murmur (ejection type), with its maximal intensity at mid systole or later (indistinguishable from that of isolated pulmonary valve stenosis [PVS]), is heard at the left sternal border and is well-conducted to the precordium, neck, and back.
• A third heart sound is audible in the presence of an associated atrial septal defect (ASD) or anomalous pulmonary vein.
• A fourth heart sound is heard at the lower left sternal border in severe cases. This fourth heart sound is associated with a large a wave in the RA and usually indicates a severe lesion.
• Note the absence of the ejection click that characterizes valvar PS.
• A loud, long, systolic crescendo-decrescendo murmur (ejection type), with its maximal intensity at mid systole or later (indistinguishable from that of isolated PVS), is heard at the left sternal border and is well-conducted to the precordium, neck, and back.
• • The murmur, although louder at the second and third left intercostal space, may be heard well at the low left sternal border.
  • The later the peak intensity of the murmur occurs, the greater the obstruction.
  • Although murmur loudness does not necessarily increase with severity, murmurs of less than grade 3/6 usually occur with mild stenosis. With moderate-to-severe stenosis, murmurs are usually systolic and grade 4/6 or louder.
  • The length of the murmur depends on duration of RV systole that, in turn, depends on severity of the stenosis. Thus, mild stenosis is associated with a short murmur, with its peak earlier than mid systole. In moderate stenosis, the murmur ends at or slightly after the aortic component of the second heart sound, which remains audible. With marked-to-severe obstruction, the murmur extends beyond the aortic component, which may be obscured.
• Infants with critical stenosis present with variable findings.
• • Heart failure is prominent.
  • A small infant with maximal obstruction may have minimal murmur (sometimes overlooked) and cyanosis.
  • An additional systolic murmur is heard in the lower left parasternal region from the tricuspid regurgitation (TR).
  • Absence of P-2 along with the presence of cardiomegaly and the holosystolic murmur of TR highly suggests a critical PS diagnosis.

Causes

See Pathophysiology.

DIFFERENTIALS

Section 4 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Other Problems to be Considered

Tumors of right ventricular outflow tract
Aneurysm of right coronary sinus
Right ventricular myxomas
Pulmonary artery stenosis (unilateral, bilateral, single or multiple, localized or diffuse)
Pulmonary artery branch stenosis

WORKUP

Section 5 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Blood investigations are helpful in acute-stage management when an infant presents with cyanosis or heart failure.

Imaging Studies

• Chest radiography
• • Heart size is usually within reference ranges but, at times, may be slightly enlarged. Pulmonary vasculature is reduced in patients with cyanosis or in those with cardiac failure.
  • Cardiomegaly or dilatation of RV may be evident in severe cases and becomes more marked with TR or cardiac failure.
  • Pulmonary vascularity is usually normal, except in severe cases with right-to-left shunt across the atrial or ventricular septa.
  • In infants with severe or critical PS, cardiomegaly with a huge cardiac silhouette is the rule. Pulmonary vascular markings are also reduced.
  • Poststenotic dilation of the main PA seen in PVS is not a feature.
• Echo-Doppler studies
• • Noninvasive echo-Doppler studies play a major role in demonstrating the presence, magnitude, and site of the obstruction. They also help find associated cardiac anomalies.
  • Echo-Doppler studies can be very useful in evaluating RV size and function and pulmonary valve anatomy.²
  • • The projections used to obtain these views are the standard and high-parasternal short axis and the subcostal sagittal views. The ventricular cavity and tricuspid valve can also be easily assessed.
    • A subcostal oblique view is especially helpful to visualize hypertrophy of the RV outflow tract (RVOT).
    • Contract echocardiography may detect the presence of right-to-left shunting at the atrial or ventricular level.
  • In mild obstruction, cardiac chambers are normal. Their only abnormality may be the hypertrophied infundibulum with a turbulent flow across it. High flow velocity is confirmed with pulsed wave and continuous wave Doppler studies.
  • In moderate-to-severe obstruction, the RV is dilated and hypertrophied, and the right atrium may also be dilated, with the atrial septum bulging toward the left atrium. In cases of dynamic obstruction that characterize the infundibular hypertrophy, a late-peaking Doppler signal is recorded across the RVOT.
  • Echo-Doppler can be used to quantify the pressure drop across the stenosed infundibulum. The peak velocity measured across the RVOT is used to calculate the pressure gradient, using the modified Bernoulli equation, p = 4V² (p is the peak instantaneous pressure gradient in mm Hg across the obstructed infundibulum, whereas V is peak flow velocity in m/sec distal to the obstructive orifice).
  • • The technique is as accurate as cardiac catheter data in prediction of pressure gradients across the RVOT.
    • Doppler studies measure the actual instantaneous pressure gradient, which is about 10% more than the peak-to-peak gradient measured using cardiac catheterization.³
  • Do not allow for possible energy losses caused by the elongated obstruction or the presence of narrowing at more than a single level in patients with infundibular obstruction.

Other Tests

• Electrocardiography
• • With mild stenosis, ECG findings are usually within reference ranges. Occasionally, a rightward shift of the main QRS frontal axis may be present.
  • Moderate-to-severe cases show right-axis deviation and RV hypertrophy, proportional to severity.
  • Except in the newborn period, the height of the R wave in right chest leads provides an assessment of the RV pressure.
  • Upright T waves and QRS in right chest leads and incomplete right bundle-branch block may be present but do not necessarily indicate severity of obstruction. Tall p waves suggest RA enlargement (p pulmonale).
  • In infants with maximal obstruction bordering on pulmonary atresia, the evidence for RV hypertrophy may be less convincing, and LV dominance is rarely observed.
  • The abrupt transition in the pattern of the QRS complex in the mid-precordial leads, a pattern often found with tetralogy of Fallot, is not seen.

Procedures

• Cardiac catheterization
• • Cardiac catheterization is not essential for diagnosis or to assess severity.
  • • The procedure is sometimes undertaken before surgical intervention and in infants for whom other associated lesions must be evaluated.
    • Occasional reports of balloon dilatation of RVOT are available, but results are not encouraging. The procedure is not recommended in patients with infundibular pulmonary stenosis (IPS).
  • Resting peak systolic pressures in the RV of more than 30-35 mm Hg, as well as pressure gradients across the stenotic infundibulum of more than 10-15 mm Hg, are considered abnormal.
  • In mild IPS, PA pressure is normal. In severe IPS, a marked reduction of mean PA pressure and obliteration of the usual pulsatile configuration of the pressure tracing are present.
  • Presence of IPS may be suggested by the withdrawal pressure tracing. In some cases of combined valvar and discrete infundibular stenosis, 2 pressure gradients may be encountered; the first at the valve and the second at the infundibular level.
  • • Pressure gradients may be encountered at more than one level, making it difficult to assess the severity of all but the most proximal stenoses.
    • In severe valvar stenosis with diffuse infundibular narrowing, a characteristic infundibular pressure pulse pattern is frequently observed.
    • End-diastolic pressure in the RV may be normal or elevated with severe obstruction or RV failure.
  • The degree of RV hypertension is the main indicator of severity. Mild stenosis is present when the proximal systolic pressure is less than 60 mm Hg. With moderate stenosis, this pressure may be as high as 100 mm Hg; above this level, the stenosis is considered severe. Other hemodynamic findings in severe stenosis include the following:
  • • RV end-diastolic and RA a wave pressures are elevated.
    • A high v wave in the right atrium indicates TR.
    • A right-to-left shunt at the atrial or ventricular level should be sought in all patients with cyanosis.
    • A left heart catheterization is indicated in all patients with subvalvular stenosis that may be a component of a hypertrophic cardiomyopathy.
• Angiocardiography
• • Right ventriculography in right anterior oblique projection demonstrates obstruction at the infundibular level.
  • The best all-purpose projection for evaluation of the pulmonary outflow tract and PAs is an anteroposterior projection with a 45° head-up tilt.
  • When taken along with the lateral projection, a good view is obtained of all the important structures.
  • This projection makes distinguishing the hourglass variant from bottle-shaped sinuses possible.
  • A 4-chamber axial oblique projection may occasionally be preferred to visualize the PA bifurcation.
  • Left-sided angiocardiography is indicated when a VSD or a left-sided obstruction is present.
  • • The long-axis oblique projection is the most useful and is the best tool to accurately diagnose this lesion.
    • Always perform biplane angiocardiography when evidence of a significant intraventricular pressure gradient has been found during cardiac catheterization.
    • Anterior projection reveals filling defects within the RV between the outflow and inflow areas.

Histologic Findings

• Isolated infundibular stenosis of the PA is a mass of muscle-fibrous tissue that creates an obstacle to blood flow in the RV.
• Morphogenetic regularities of compensatory and adaptive reactions in isolated infundibular stenosis are similar to those in hypertrophic cardiomyopathy.
• Some have suggested that abnormalities in the structure of the hypertrophied myocardium in isolated stenosis of the RV infundibulum are caused by a fundamental error in the cardiac morphogenesis and do not reflect an increased degree of cardiac hypertrophy.

TREATMENT

Section 6 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

The primary function of medical management is to assess the severity and progression of stenosis.

• A decision must be made as to when the gradient is sufficiently severe to warrant relieving the obstruction.
• Balloon valvoplasty does not offer significant relief; carefully evaluate the role of surgery.
• Careful follow-up is necessary for children younger than 12 years because changes in the severity of their conditions are not uncommon.
• Follow-up is conducted almost wholly by echo-Doppler studies.
• If diagnostic questions arise after careful echo-Doppler evaluation, cardiac catheterization and angiography are sometimes performed before surgical intervention.
• The main indicators of progression are the degree of RV hypertrophy on ECG and echocardiography and the peak and mean systolic pressure gradients across the pulmonary outflow. Onset of symptoms (eg, hypoxic spells, angina, signs of CHF, radiological evidence of cardiomegaly) also influences the decision to surgically intervene.
• Heart failure therapy is indicated only as a temporary measure in patients with heart failure. Supervise heart failure therapy closely to look for signs of worsening. Ensure adequate hydration and, if necessary, use beta-adrenergic blockers to relax the infundibular muscles.
• Prior to surgical intervention, administration of alprostadil minimizes cyanosis in neonates with ductal-dependent pulmonary blood flow.
• Even after surgical intervention, infective endocarditis (IE) prophylaxis is recommended throughout life, irrespective of the severity of stenosis.⁴
• The use of cutting balloons to relieve infundibular stenosis associated with tetralogy of Fallot has been reported, although the presence of significant infundibular pulmonary stenosis (IPS) is not generally considered suitable for balloon angioplasty.

Surgical Care

• In general, interventions for patients with IPS include the following:
• • Corrective surgery, specifically resection of the hypertrophied infundibulum and enlargement of outflow tract with patch, if required
  • Conduit repair of outflow for severe cases in infancy (Some have achieved good results using a conduit to bypass the obstructed outflow segment.)
  • Insertion of a Blalock Taussig shunt (used only for infants with an inoperable lesion or in cases in which surgical skills are not available)
• Indications for surgical intervention include the following:
• • Presence of such symptoms as shortness of breath, cyanosis, chest pain
  • Severe stenosis with gradients exceeding 100 mm Hg, even if the patient is asymptomatic
  • Severe cyanosis or heart failure in infancy

Consultations

• Pediatric cardiologist
• Radiologist
• Family physician
• Occupational therapist
• Physiotherapist
• Psychologist
• School teacher
• Specialist nurse
• Pharmacist
• Dietitian

Diet

• The severity of malnutrition determines dietary requirements.

Activity

• No activity restrictions are necessary for patients with mild-to-moderate stenosis. Allow patients to limit their own activity, based on personal tolerance.
• Avoid dehydration at all costs.

MEDICATION

Section 7 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Surgery is the mainstay of treatment for significant stenosis. Antibiotics for endocarditis prophylaxis are given to patients with infundibular pulmonary stenosis (IPS) before performing procedures that may cause bacteremia. Endocarditis prophylaxis is recommended throughout life, even after surgical relief. For more information, see Antibiotic Prophylactic Regimens for Endocarditis. Heart failure therapy is indicated only as a temporary measure for patients with heart failure. Ensure adequate hydration before administering diuretics because the cardiac output depends on adequate preload; if necessary, use beta-adrenergic blockers to relax the infundibular muscles. Alprostadil minimizes cyanosis in neonates with ductal-dependent pulmonary circulation.

Drug Category: Beta-adrenergic blocking agents

These agents inhibit beta1- and beta2-adrenergic receptors. They inhibit chronotropic, inotropic and vasodilatory responses to beta-adrenergic stimulation. Their exact mechanism of benefit is uncertain, although it is believed to relieve infundibular spasm.

Drug Category: Diuretics

These agents are used to eliminate retained fluid and lower preload. They promote excretion of water and electrolytes by the kidneys. They are used to treat heart failure or hepatic, renal, or pulmonary disease when sodium and water retention has resulted in edema or ascites.

Drug Category: Prostaglandins

These agents are used to maintain patency of ductus arteriosus in patients with duct-dependent circulation.

FOLLOW-UP

Section 8 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• Subsequent hospitalization is required only for cardiac catheter studies, when indicated, or for surgical intervention.

Further Outpatient Care

• Regular follow-up is essential to assess progression of the obstruction.

Transfer

• When age appropriate, transfer the patient to a cardiologist specializing in adults.

Deterrence/Prevention

• Instruct patients to limit their own activity, based on personal tolerance.

Complications

• Increasing severity of stenosis
• Endocarditis
• Significant residual pulmonary regurgitation and right heart failure (rare)
• RV infarction
• RV endocardial fibroelastosis
• Cardiac arrhythmias
• Syncope
• Sudden death

Prognosis

• Prognosis mainly depends on the severity of stenosis in the absence of any additional lesions.
• Patients with mild-to-moderate stenosis live normal lives with no symptoms, apart from the risk of IE.
• Severely affected patients are at risk of death at any time throughout their lives. Patients at highest risk are those with symptoms in the first year of life, as well as those with congestive cardiac failure or paroxysmal dyspneic episodes.

Patient Education

• Educate patients about the disease and its natural history.
• Make patients aware of the need for regular follow-up.
• Educate patients on the importance of good oral hygiene.
• Patients should also become aware of the need for endocarditis prophylaxis during dental and other surgical procedures.
• For excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education article Tetralogy of Fallot.

MISCELLANEOUS

Section 9 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Presuming asymptomatic patients to have mild stenosis without detailed evaluation
• Diagnosing mild stenosis because of the absence of pulmonary oligemia on chest radiography
• Missing associated lesions, such as coexisting valve or supravalvar stenosis, VSD, ASD, and hypoplasia of RV
• Confusing PS with double-outlet RV

MULTIMEDIA

Section 10 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  Chest radiograph of a 2-year-old boy with severe pulmonary stenosis (infundibular). Note the mild cardiomegaly, reduced pulmonary vascularity, and absence of poststenotic dilatation of pulmonary artery.
	View Full Size Image
Media type:  Radiograph

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

1. Marton T, Hajdu J, Papp C, et al. Pulmonary stenosis and reactive right ventricular hypertrophy in the recipient fetus as a consequence of twin-to-twin transfusion. Prenat Diagn. Jun 2001;21(6):452-6. [Medline].
2. Joy MV, Subramonium R, Venkitachalam CG, Balakrishnan KG. Two dimensional and Doppler echocardiographic evaluation of double chambered right ventricle. Indian Heart J. May-Jun 1992;44(3):159-63. [Medline].
3. Nakajima T, Arakaki Y, Kamiya T, et al. Doppler echocardiographic estimates of pressure gradients in various types of stenoses: usefulness and limitations [in Japanese]. J Cardiol. Sep 1989;19(3):851-8. [Medline].
4. Sahin T, Bildirici U, Kandemir C, Celikyurt U, Ural D, Komsuoglu B. Infective endocarditis in the setting of infundibular-valvular pulmonary stenosis with incomplete cor triatriatum dextrum and patent foramen ovale. Int J Cardiol. Jul 21 2008;127(3):e129-31. [Medline].
5. Alekian BG, Petrosian IuS, Podzolkov VP, et al. Catheter therapy of congenital cardiovascular defects [in Russian]. Vestn Rentgenol Radiol. Mar-Apr 1995;(2):16-26. [Medline].
6. Alipour MS, Shadkhoo G, Tarbiat C. Congenital pulmonary valvular and infundibular stenosis complicating Ebstein's anomaly of the tricuspid valve. A case report. Jpn Heart J. Nov 1980;21(6):883-90. [Medline].
7. Bhandari S, Dev V, Shrivastava S, Bhatia ML. Echocardiographic demonstration of pulmonary valve vegetation in a child with infundibular pulmonic stenosis and closed VSD. Indian Heart J. Sep-Oct 1986;38(5):425-8. [Medline].
8. Brown JW, Ruzmetov M, Rodefeld MD, et al. Valved bovine jugular vein conduits for right ventricular outflow tract reconstruction in children: an attractive alternative to pulmonary homograft. Ann Thorac Surg. Sep 2006;82(3):909-16. [Medline].
9. Carlson KM, Neish SR, Justino H, et al. Use of cutting balloon for palliative treatment in tetralogy of Fallot. Catheter Cardiovasc Interv. Apr 2005;64(4):507-12. [Medline].
10. Caspi J, Coles JG, Benson LN, et al. Management of neonatal critical pulmonic stenosis in the balloon valvotomy era. Ann Thorac Surg. Feb 1990;49(2):273-8. [Medline].
11. Conte S, Jashari R, Eyskens B, et al. Homograft valve insertion for pulmonary regurgitation late after valveless repair of right ventricular outflow tract obstruction. Eur J Cardiothorac Surg. Feb 1999;15(2):143-9. [Medline].
12. Daskalopoulos DA, Pieroni DR, Gingell RL, et al. Closed transventricular pulmonary valvotomy in infants. J Thorac Cardiovasc Surg. Aug 1982;84(2):187-91. [Medline].
13. Delhaas T, Prinzen FW. Sequelae of DDD pacing in patients with pulmonary infundibular stenosis [letter]. Am J Cardiol. Nov 1 1999;84(9):1142. [Medline].
14. Fawzy ME, Awad M, Galal O, et al. Long-term results of pulmonary balloon valvulotomy in adult patients. J Heart Valve Dis. Nov 2001;10(6):812-8. [Medline].
15. Freed MD, Heymann MA, Lewis AB, et al. Prostaglandin E1 infants with ductus arteriosus-dependent congenital heart disease. Circulation. Nov 1981;64(5):899-905. [Medline].
16. Galal O, Kalloghlian A, Pittappilly BM, Dzimiri N. Phentolamine improves clinical outcome after balloon valvoplasty in neonates with severe pulmonary stenosis. Cardiol Young. Mar 1999;9(2):127-8. [Medline].
17. Gibbs JL, Uzun O, Blackburn ME, et al. Right ventricular outflow stent implantation: an alternative to palliative surgical relief of infundibular pulmonary stenosis. Heart. Feb 1997;77(2):176-9. [Medline]. [Full Text].
18. Glen S, Burns J, Bloomfield P. Prevalence and development of additional cardiac abnormalities in 1448 patients with congenital ventricular septal defects. Heart. Nov 2004;90(11):1321-5. [Medline]. [Full Text].
19. Goebel N, Gander MP. [Echinococcus of the heart. Infundibular pulmonary stenosis due to a large solitary cyst of the ventricular septum (author's transl)]. Rofo. Jan 1977;126(1):11-4. [Medline].
20. Gupta D, Saxena A, Kothari SS, Juneja R. Factors influencing late course of residual valvular and infundibular gradients following pulmonary valve balloon dilatation. Int J Cardiol. Jul 2001;79(2-3):143-9. [Medline].
21. Harinck E, Becker AE, Groot AC, et al. The left ventricle in congenital isolated pulmonary valve stenosis. A morphological study. Br Heart J. Apr 1977;39(4):429-35. [Medline].
22. Houston AB, Simpson IA, Sheldon CD, et al. Doppler ultrasound in the estimation of the severity of pulmonary infundibular stenosis in infants and children. Br Heart J. Apr 1986;55(4):381-4. [Medline].
23. Ilbawi M, Cua C, DeLeon S, et al. Repair of complete atrioventricular septal defect with tetralogy of Fallot. Ann Thorac Surg. Sep 1990;50(3):407-12. [Medline].
24. Imafuku T, Ogihara T, Kudo H, et al. Kartagener's syndrome associated with infundibular pulmonic stenosis, chronic renal failure and azoospermia: a report of a case. Jpn J Med. May 1986;25(2):195-8. [Medline].
25. Isomura T, Hisatomi K, Hirano A, et al. Ruptured aneurysms of the sinus of Valsalva. J Cardiovasc Surg (Torino). Apr 1994;35(2):135-8. [Medline].
26. Jackson F. The heart at high altitude. Br Heart J. May 1968;30(3):291-4. [Medline].
27. Keith A. Malformation of the heart. Lancet. 1909;2:359.
28. Khikmatov AA. Changes in intracardiac hemodynamics during of the natural course of isolated stenoses of pulmonary artery and the right ventricular outflow tract [in Russian]. Ter Arkh. 2001;73(9):73-6. [Medline].
29. Kirklin JW, Blackstone EH, Jonas RA, et al. Morphologic and surgical determinants of outcome events after repair of tetralogy of Fallot and pulmonary stenosis. A two-institution study. J Thorac Cardiovasc Surg. Apr 1992;103(4):706-23. [Medline].
30. Krabill KA, Wang Y, Einzig S, Moller JH. Rest and exercise hemodynamics in pulmonary stenosis: comparison of children and adults. Am J Cardiol. Aug 1 1985;56(4):360-5. [Medline].
31. Kraiem S, Hmem M, Longo S, et al. Double chamber right ventricle. About 3 cases [in French]. Tunis Med. May 2006;84(5):316-20. [Medline].
32. Kronik G, Fitscha P, Slany J, Mösslacher H. [Echocardiographic diagnosis of subpulmonic obstruction in hypertrophic cardiomyopathy (a case report) (author's transl)]. Z Kardiol. Jun 1979;68(6):415-8. [Medline].
33. Latsis AT, Iagmanis MIa, Kreile IE, Trushelis E. Correction of a partially patent atrioventricular canal with a common atrium, infundibular and valvular stenosis of the pulmonary artery and a single (left) superior vena cava [in Russian]. Grud Serdechnososudistaia Khir. Feb 1991;(2):53-5. [Medline].
34. Levin DL, Heymann MA, Rudolph AM. Morphological development of the pulmonary vascular bed in experimental pulmonic stenosis. Circulation. Jan 1979;59(1):179-82. [Medline].
35. Lucas RV, Varco RL, Lillehei CW, et al. Anomalous muscle bundle of the right ventricle. Hemodynamic consequences and surgical considerations. Circulation. Mar 1962;25:443-55. [Medline].
36. Mantri RR, Bajaj R, Shrivastava S. Multiple anomalies of caval veins in a patient with pulmonic stenosis. Int J Cardiol. Sep 1994;46(2):172-4. [Medline].
37. McQuinn TC, Miga DE, Mjaatvedt CH, et al. Cardiopulmonary malformations in the inv/inv mouse. Anat Rec. May 1 2001;263(1):62-71. [Medline].
38. Mehan VK, Meier B. Interventional cardiology: state of the art. Presse Med. Feb 19 1994;23(7):339-44. [Medline].
39. Mori F, Tsuboi H, Ohmi M, et al. Noonans syndrome associated with atrial septal defect, ventricular septal defect and infundibular pulmonary stenosis--a case report [in Japanese]. Nippon Kyobu Geka Gakkai Zasshi. Jun 1983;31(6):936-9. [Medline].
40. Moura C, Carrico A, Baptista MJ, et al. Balloon pulmonary valvotomy performed in the first year of life. Rev Port Cardiol. Jan 2004;23(1):55-63. [Medline].
41. Patel R, Astley R. Right ventricular obstruction due to anomalous muscle bands. Br Heart J. Sep 1973;35(9):890-3. [Medline].
42. Pogrebniak VV, Tereshchenko VP, Zin'kovskii MF, Zurnadzhi IuN, Chumak OS. [Morphogenetic patterns of isolated infundibular stenosis of the pulmonary artery]. Vrach Delo. Sep 1989;44-6. [Medline].
43. Pongiglione G, Freedom RM, Cook D, Rowe RD. Mechanism of acquired right ventricular outflow tract obstruction in patients with ventricular septal defect: an angiocardiographic study. Am J Cardiol. Oct 1982;50(4):776-80. [Medline].
44. Qureshi SA, Parsons JM, Tynan M. Percutaneous transcatheter myectomy of subvalvar pulmonary stenosis in tetralogy of Fallot: a new palliative technique with an atherectomy catheter. Br Heart J. Aug 1990;64(2):163-5. [Medline].
45. Rao PS. Transcatheter management of cyanotic congenital heart defects: a review. Clin Cardiol. Jul 1992;15(7):483-96. [Medline].
46. Rao PS, Wilson AD, Thapar MK, Brais M. Balloon pulmonary valvuloplasty in the management of cyanotic congenital heart defects. Cathet Cardiovasc Diagn. Jan 1992;25(1):16-24. [Medline].
47. Raut NB, Norton JB, Patil AA. Bourneville's tuberous sclerosis associated with double outlet right ventricle and infundibular pulmonary stenosis. J Assoc Physicians India. Jul 1992;40(7):469-70. [Medline].
48. Rowland TW, Rosenthal A, Castaneda AR. Double-chamber right ventricle: experience with 17 cases. Am Heart J. Apr 1975;89(4):455-62. [Medline].
49. Rummeny E, Hausen W, Lorbacher P, Willems D. Acquired infundibular pulmonary stenosis. Possible late complication following radiotherapy of Hodgkin disease [in German]. Z Kardiol. Oct 1984;73(10):641-5. [Medline].
50. Shenoy AR, Padmakumar P, Subashchandra V. Right ventricular outflow tract stenting in tetrology of fallot with restrictive ventricular septal defect. J Invasive Cardiol. Jan 2006;18(1):E59-60. [Medline].
51. Shimada Y, Yaku H, Kawata M, et al. Surgical repair of primary infundibular stenosis in a 72-year-old man. ANZ J Surg. Aug 2001;71(8):498-9. [Medline].
52. Shishkov BV, Nikoliuk AP, Garibian VA, et al. Surgical tactics in critical stenosis and atresia of the pulmonary artery with intact interventricular septum in infants under 1 year of age [in Russian]. Grud Serdechnososudistaia Khir. Sep 1991;11-4. [Medline].
53. Sholler GF, Colan SD, Sanders SP. Effect of isolated right ventricular outflow obstruction on left ventricular function in infants. Am J Cardiol. Oct 1 1988;62(10 Pt 1):778-84. [Medline].
54. Simpson WF Jr, Sade RM, Crawford FA, et al. Double-chambered right ventricle. Ann Thorac Surg. Jul 1987;44(1):7-10. [Medline].
55. Takahashi T, Sakakibara T, Nomura F, et al. A case report of isolated infundibular pulmonary stenosis with pouch of the infundibular chamber [in Japanese]. Nippon Kyobu Geka Gakkai Zasshi. Jun 1989;37(6):1197-201. [Medline].
56. Tanner K, Sabrine N, Wren C. Cardiovascular malformations among preterm infants. Pediatrics. Dec 2005;116(6):e833-8. [Medline].
57. Tereshchenko VP, Pogrebniak VV, Ishchenko VE, et al. The structure of isolated infundibular stenosis of the pulmonary artery [in Russian]. Vrach Delo. Jun 1990;(6):31-2. [Medline].
58. Wu MH, Wu JM, Chang CI, et al. Implication of aneurysmal transformation in isolated perimembranous ventricular septal defect. Am J Cardiol. Sep 1 1993;72(7):596-601. [Medline].
59. Yamagishi M, Nakamura Y, Kanazawa T, Kawada N. Extracardiac direct total cavopulmonary connection. Ann Thorac Surg. Dec 1997;64(6):1817-9; discussion 1819-20. [Medline].
60. Yamamoto T, Habuchi Y, Morikawa J. Single coronary artery with infundibular pulmonary stenosis. Heart. Aug 1997;78(2):205-6. [Medline].
61. Zacherl S, Feyertag C, Salzer-Muhar U, Wimmer M. Bacterial endocarditis in childhood [in German]. Klin Padiatr. Mar-Apr 1996;208(2):47-52. [Medline].

Article Last Updated: Jul 25, 2008