Pulmonary Stenosis

Valvular disorders can arise from the pulmonary valve, located between the right ventricle (RV) and the pulmonary artery (PA). Valvular disorders are diagnosed by echocardiography. Pulmonary stenosis (PS) is valvular narrowing causing RV outflow tract obstruction. Patients are often asymptomatic unless they have other congenital cardiac anomalies or severe PS. Symptoms (exertional dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain, and syncope Syncope Syncope is a short-term loss of consciousness and loss of postural stability followed by spontaneous return of consciousness to the previous neurologic baseline without the need for resuscitation. The condition is caused by transient interruption of cerebral blood flow that may be benign or related to a underlying life-threatening condition. Syncope) are due to RV failure. Severe PS is treated surgically.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

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Overview

Anatomy

Pulmonary (or pulmonic) valve:

  • Semilunar valve between the right ventricle (RV) and pulmonary artery (PA)
  • Consists of 3 cusps: anterior, left, and right
  • Opens during systole as the RV pressure exceeds the pulmonary trunk pressure
  • Closes during diastole as the RV pressure drops (S2), preventing retrograde flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure from the pulmonary trunk
Table: Overview of pulmonary valve disorders
Pulmonary stenosis (PS)Pulmonary regurgitation (PR)
Etiology Mostly congenital Mostly acquired
Murmur Systolic murmur, left upper sternal border (preceded by a systolic click that decreases with inspiration) Diastolic murmur, left upper sternal border, increases with inspiration
S2 Split S2 with soft and delayed P2 Split S2 with a loud P2
Echocardiographic findings Thick and domed leaflets, with increased systolic velocity across the valve, RVH Valvular abnormalities (depending on etiology), RV enlargement, and a regurgitant jet in the right ventricular outflow tract
RV: right ventricle
RVH: right ventricular hypertrophy

Definition and Epidemiology

Definition

Pulmonary stenosis is the narrowing of the pulmonary valve causing:

  • An increased pressure gradient across the valve
  • An obstruction to the flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure from the RV to the PA
Pulmonary valve stenosis

Differentiation of the normal heart with a normal pulmonary valve and a heart with pulmonary valve stenosis

Image: “Pulmonary valve stenosis” by LadyofHats. License: Public domain.
  • Affects 7% of children with congenital heart defects
  • Women > men
  • Mild PS: good prognosis, with no difference from unaffected population
  • Severe PS: 
    • Without treatment, advances to RV outflow obstruction
    • Intervention required by majority of affected patients within 10 years of diagnosis

Etiology and Classification

Etiology

  • Cases are often congenital:
    • Isolated valvular PS: 
      • 10% of congenital heart disease
      • Valve is typically dome shaped.
    • Other congenital forms:
      • As part of Noonan syndrome: 
        • 50% of cases are associated with the PTPN1 gene mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations.
        • Usually with dysplastic valves
      • Tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot (TOF):
        • Pulmonary valve stenosis 
        • Overriding aorta
        • RVH
        • Ventricular septal defect (VSD)
      • Congenital rubella Rubella Rubella (also known as German measles or three-day measles) is caused by a single-stranded, positive-sense RNA virus of the Togaviridae family. Rubella only infects humans and spreads prenatally via vertical transmission or postnatally via droplet contact. Congenital rubella is associated with a classic triad of symptoms: cataracts, cardiac defects, and deafness. Infection in children and adults may be mild and present with constitutional symptoms along with a viral exanthem. Rubella Virus syndrome
  • Acquired PS:
    • Carcinoid syndrome Carcinoid syndrome Carcinoid tumors are small, well-differentiated, slow-growing neuroendocrine tumors (NET). Carcinoid syndrome describes the signs and symptoms associated with unregulated vasoactive hormone production by neuroendocrine tumors. Carcinoid tumors are most commonly found in the GI and bronchopulmonary tracts. Carcinoid Tumors and Syndrome
    • Rheumatic heart disease (rarely involves PS)
    • Previous cardiothoracic surgeries
Tetralogy of fallot

Comparison of the normal heart and a heart with TOF: pulmonary valve stenosis, overriding aorta, RVH, VSD

Image: “ Tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot” by LadyofHats. License: Public domain.

Types of stenosis

  • Valvular PS: 
    • Narrowed or thickened valve
    • Most common type
    • Associated with TOF, congenital rubella Rubella Rubella (also known as German measles or three-day measles) is caused by a single-stranded, positive-sense RNA virus of the Togaviridae family. Rubella only infects humans and spreads prenatally via vertical transmission or postnatally via droplet contact. Congenital rubella is associated with a classic triad of symptoms: cataracts, cardiac defects, and deafness. Infection in children and adults may be mild and present with constitutional symptoms along with a viral exanthem. Rubella Virus syndrome, Noonan syndrome, acquired PS from carcinoid syndrome
  • Subvalvular infundibular PS:
    • Fibromuscular narrowing of the infundibular region, with normal valve
    • Rare
    • Can be found with other congenital lesions (TOF, VSD)
  • Supravalvular (or peripheral) PS: 
    • Narrowing of the main PA or its branches, up to the periphery
    • Murmurs heard over the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs
    • Mild form: nonpathologic, with murmur resolving by 6 months of age
    • Associated with congenital rubella Rubella Rubella (also known as German measles or three-day measles) is caused by a single-stranded, positive-sense RNA virus of the Togaviridae family. Rubella only infects humans and spreads prenatally via vertical transmission or postnatally via droplet contact. Congenital rubella is associated with a classic triad of symptoms: cataracts, cardiac defects, and deafness. Infection in children and adults may be mild and present with constitutional symptoms along with a viral exanthem. Rubella Virus syndrome or other anomalies (TOF, patent ductus arteriosus Patent ductus arteriosus The ductus arteriosus (DA) allows blood to bypass pulmonary circulation. After birth, the DA remains open for up to 72 hours and then constricts and involutes, becoming the ligamentum arteriosum. Failure of this process to occur results in patent ductus arteriosus (PDA), a condition that causes up to 10% of congenital heart defects. Patent Ductus Arteriosus (PDA), VSD)

Pathophysiology and Clinical Presentation

Pathophysiology

  • PS causes sustained outflow tract obstruction, which increases right ventricular afterload. 
  • RV is less adaptive than the left ventricle, with early rises in pressures; so, with lower systolic pressures, RVH occurs.
  • Right atrial (RA) pressure increases as a result of elevated RV pressure.
  • Late in the disease: persistently increased RV strain → RV dysfunction occurs → eventual RV failure
  • Other complications: arrhythmia, infective endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis

Symptoms

  • Commonly asymptomatic during mild-to-moderate disease (majority of patients)
  • Severe PS:
    • The more severe the obstruction is, the earlier it is detected.
    • Fatigue and exertional dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea 
    • Anginal chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain from oxygen supply-demand mismatch
    • Syncope especially when accompanied by provoking factors (e.g., atrial fibrillation Atrial fibrillation Atrial fibrillation (AF or Afib) is a supraventricular tachyarrhythmia and the most common kind of arrhythmia. It is caused by rapid, uncontrolled atrial contractions and uncoordinated ventricular responses. Atrial Fibrillation, infection)

Signs

  • Prominent a wave in jugular venous pulse (strong atrial contraction)
  • Heart sounds Heart sounds Heart sounds are brief, transient sounds produced by valve opening and closure and by movement of blood in the heart. They are divided into systolic and diastolic sounds. In most cases, only the first (S1) and second (S2) heart sounds are heard. These are high-frequency sounds and arise from aortic and pulmonary valve closure (S1), as well as mitral and tricuspid valve closure (S2). Heart Sounds:
    • A high-pitched crescendo-decrescendo (diamond-shaped) systolic ejection murmur heard at the left upper sternal border (2nd intercostal space)
    • Murmur preceded by a pulmonary ejection click, which decreases with inspiration (the only right-sided sound that decreases with inspiration)
    • P2 delayed (wide S2 splitting)
    • Right-sided S3, S4 (RV failure)
  • Left parasternal lift (from RVH) in severe PS
  • Cyanosis in those with a right-to-left shunt (e.g., atrial septal defect Atrial Septal Defect Atrial septal defects (ASDs) are benign acyanotic congenital heart defects characterized by an opening in the interatrial septum that causes blood to flow from the left atrium (LA) to the right atrium (RA) (left-to-right shunt). Atrial Septal Defect)
  • Very late in the course: peripheral edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, hepatomegaly, ascites Ascites Ascites is the pathologic accumulation of fluid within the peritoneal cavity that occurs due to an osmotic and/or hydrostatic pressure imbalance secondary to portal hypertension (cirrhosis, heart failure) or non-portal hypertension (hypoalbuminemia, malignancy, infection). Ascites

Diagnosis

  • Transthoracic echocardiography (TTE) with Doppler: 
    • 2-dimensional (2D) and Doppler echocardiogram confirms the diagnosis.
    • Findings: 
      • Pulmonary valve thickening, doming of the valves
      • RVH, narrowed RV outflow tract
      • Post-stenotic dilation of the PA
      • Associated cardiac defects
      • Increased transvalvular gradient between the RV and the PA
    • Grading Grading Cancer is the 2nd leading cause of death in the US after cardiovascular disease. Many malignancies are treatable or curable, but some may recur. Thus, all malignancies must be assigned a grade and stage in order to guide management and determine prognosis. Grading, Staging, and Metastasis:
      • Mild PS: peak Doppler gradient < 30 mm Hg
      • Moderate PS: peak Doppler gradient of 30–50 mm Hg
      • Severe PS: peak Doppler gradient across the pulmonary valve of > 50 mm Hg
  • Transesophageal echocardiography (TEE):
    • Use when assessing for infective endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis.
    • Not indicated for routine diagnosis of PS
  • Electrocardiogram Electrocardiogram An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Normal Electrocardiogram (ECG) ( ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Normal Electrocardiogram (ECG)): 
    • Right axis deviation, RVH, right atrial enlargement
    • Right bundle branch block
  • Chest X-ray: 
    • Frontal view: 
      • Prominent PA from post-stenotic dilation
      • Lifting of the cardiac apex off the diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm
      • Prominent right heart border from RA enlargement
    • Lateral view: filling of the retrosternal space by the enlarged RV
  • Cardiac magnetic resonance imaging:
    • An option if TTE is suboptimal
    • Evaluates severity of the valve abnormalities and branch PA flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure
    • Delineates anatomy of the PA and right heart
  • Cardiac catheterization and pulmonary angiography:
    • Not necessary for the diagnosis of PS
    • Performed if clinical findings and echocardiographic findings are inconclusive
    • Provides information about concomitant congenital abnormalities

Management

  • Monitoring:
    • Asymptomatic, with peak Doppler gradient < 30 mm Hg: physical examination, Doppler echocardiography, ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Normal Electrocardiogram (ECG) every 5 years 
    • Asymptomatic, with peak Doppler gradient > 30 mm Hg: Doppler echocardiography every 2–5 years
  • Diuretics: for symptoms of RV overload
  • Percutaneous balloon valvotomy:
    • Symptomatic patients with a domed valve and a peak gradient > 50 mm Hg (or a mean gradient > 30 mm Hg)
    • Asymptomatic patients with a peak gradient > 60 mm Hg (or a mean gradient > 40 mm Hg)
  • Surgical valvotomy for severe PS associated with:
    • Hypoplastic pulmonary annulus
    • Severe pulmonary regurgitation
    • Subvalvular PS
    • Most dysplastic valves
    • Severe tricuspid regurgitation Tricuspid regurgitation Tricuspid regurgitation (TR) is a valvular defect that allows backflow of blood from the right ventricle to the right atrium during systole. Tricuspid regurgitation can develop through a number of cardiac conditions that cause dilation of the right ventricle and tricuspid annulus. A blowing holosystolic murmur is best heard at the left lower sternal border. Tricuspid Regurgitation
    • Surgical cardiac condition requiring operative intervention

Clinical Relevance

  • TOF: cyanotic congenital heart disease characterized by the tetrad of RVH, an overriding aorta, pulmonary valve stenosis, and a ventricular septal defect. Surgically corrected TOF is a common cause for subsequent pulmonary regurgitation.
  • Pulmonary atresia: a rare congenital cyanotic heart disease characterized by the failed formation of the pulmonary valve, leading to subsequent RV hypoplasia. Pulmonary atresia may occur as part of the most severe form of TOF (with VSD), where the entire RV outflow enters the aorta.
  • Carcinoid syndrome Carcinoid syndrome Carcinoid tumors are small, well-differentiated, slow-growing neuroendocrine tumors (NET). Carcinoid syndrome describes the signs and symptoms associated with unregulated vasoactive hormone production by neuroendocrine tumors. Carcinoid tumors are most commonly found in the GI and bronchopulmonary tracts. Carcinoid Tumors and Syndrome: small, slow-growing neuroendocrine tumors. The tumors are associated with unregulated vasoactive hormone production, inducing the development of fibrous endocardial plaques and leading to pulmonary and tricuspid valve abnormalities.
  • Rheumatic fever Rheumatic fever Acute rheumatic fever (ARF) is an autoimmune inflammatory process that usually follows Streptococcal pharyngitis. Acute rheumatic fever usually occurs 2-4 weeks after an untreated infection and affects the heart, skin, joints, and nervous system. Rheumatic Fever: a late complication of untreated streptococcal pharyngeal infection characterized by valvular abnormalities, most commonly of the left heart. While rare, the pulmonary valve can be affected concurrently with the mitral valve.

References

  1. Hoit, B.D. (2017). Tricuspid & pulmonic valve disease. Crawford M.H. (Ed.), Current, Diagnosis & Treatment: Cardiology, 5th ed. McGraw-Hill.
  2. Jone, P., Kim, J.S., Alvensleben, J., & Burkett, D. (2020). Cardiovascular diseases. In Hay Jr., W.W., Levin, M.J., Abzug, M.J., & Bunik, M (Eds.), Current Diagnosis & Treatment: Pediatrics, 25th ed. McGraw-Hill.
  3. Loewenthal, M., & O’Connor, R. (2016). Pulmonic valvular stenosis. Medscape. https://emedicine.medscape.com/article/759890-overview
  4. O’Gara P.T., & Loscalzo, J. (2018). Pulmonic valve disease. In Jameson, J., Fauci, A.S., Kasper, D.L., Hauser, S.L., Longo, D.L., & Loscalzo, J. (Eds.) Harrison’s Principles of Internal Medicine, 20th ed. McGraw-Hill.
  5. Stout, K., Connolly, H., & Yeon, S. (2018). Natural history and treatment of pulmonic stenosis in adults. UpToDate. Retrieved from Nov 3, 2020, from https://www.uptodate.com/contents/natural-history-and-treatment-of-pulmonic-stenosis-in-adults
  6. Sundjaja, J., & Bordoni, B. (2019) Anatomy, Thorax, Heart, Pulmonic valve. https://www.ncbi.nlm.nih.gov/books/NBK547706/
  7. Ren, X., & Lange, R. (2017) Pulmonic Stenosis. Medscape. https://emedicine.medscape.com/article/157737-overview

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