Right ventricular outflow tract obstruction

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Keri Shafer, M.D. [3] Mohammed Salih, MD. [4]

Right ventricular outflow tract (RVOT) and/or pulmonary artery obstruction are present in some form in 25 % of all congenital heart defects. The right ventricular outflow tract obstruction includes stenosis or narrowing of the pulmonary valve, the tissue above the valve (supravalvar obstruction) and below it(subvalvar obstruction). Congenital subvalvar and supravalvar right ventricular outflow tract stenosis usually occurs with other congenital heart defects such as Ventricular Septal Defect (VSD) or Tetralogy of Fallot. The timing and type of surgery will vary from patient to patient depending upon the severity of the obstruction and the associated congenital defect.

If right ventricular outflow tract obstruction is present and the ventricular septum is intact, usually the right ventricle will adapt better given that no right to left shunting is present. This absence of shunting may result in sufficient pulmonary blood flow to allow the patient to remain asymptomatic longer.

Usually therapy is directed to increase pulmonary blood flow and decompressing the right ventricle (RV) and it will depend on the severity and location of the defect. According to the anatomic features of the pulmonary valve stenosis, the physician may use balloon dilatation (a minimally invasive transvenous procedure) to dilate the obstruction during cardiac catheterization, but if the pulmonary artery is the structure involved, stenting (insertion of a small tube) within the narrowed region can be done following balloon angioplasty. Standard treatment of right ventricular outflow tract or pulmonary artery obstruction involves open chest surgery. ^{[1] [2][3] [4] [5]}

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Synonyms and keywords: Pulmonic valve

The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps.

Similar to the aortic valve, the pulmonic valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the pulmonary artery. At the end of ventricular systole, when the pressure in the right ventricle falls rapidly, the pressure in the pulmonary artery will close the pulmonic valve.

The closure of the pulmonic valve contributes the P2 component of the second heart sound (S2).

The right heart is a low-pressure system, so the P2 component of the second heart sound is usually softer than the A2 component of the second heart sound. However, it is physiologically normal in some young people to hear both components separated during inhalation.

• Pulmonary valve is located at the distal part of the right ventricular outflow tract at the junction of the pulmonary artery.
• It is located anterior and superior to the aortic valve at the level of the third intercostal space and separated from the tricuspid valve by the infundibulum of the right ventricle. ^[1]
• It is comprised of three equal sized, semilunar cusps or leaflets (right, left, anterior), nomenclature based on the corresponding aortic valve. ^{[2] [2]}
• The three cusps are joined by commissures and the cusps are thinner when compared to the aortic valve, due to a low pressure in the right ventricle.^[2]
• The area of the valve is related to body surface area and men usually have greater valve area when compared with women.
• The normal orifice area is approximately around 3cm². ^[3]
• The pulmonary valve opens in the right ventricular systole allowing the deoxygenated blood to be delivered to the lungs. ^[2]
• During the right ventricular diastole the pulmonary valves close completely to prevent regurgitation of blood into the right ventricle.^[2]

• Heart valve

nn:Pulmonalklaff

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

pulmonic stenosis is most commonly secondary to acute rheumatic fever. Generally, the initial valvulitis is associated with valvular regurgitation but over a period of 2 or more years, the commissures fuse and the valves thicken and calcify. The chordal supporting structure also calcifies and retracts. The result is the typical “fish mouth deformity”. 70% of the time; the mitral valve is involved in isolation, and 25% of the time; the aortic valve is involved as well. The tricuspid and pulmonic valves are involved less commonly. Patients develop symptoms when the mitral vavle area is 2 to 2.5 cm².

Almost all cases of pulmonic stenosis are due to disease in the heart secondary to rheumatic fever and the consequent rheumatic heart disease (a condition that may develop after strep throat or scarlet fever). Around 90% of cases of rheumatic heart disease are associated with pulmonic stenosis. Pulmonic stenosis is a progressive valvular disease which progression depends mainly on the degree of the narrowing of the pulmonic valve as well as on the maladaptive ventricular wall response. ^{[1] [2][3] [4] [5] [5] [6] [4] [7] [8] [9] [10] [11] [5] [5][5] [12] [12] [13] [12]}

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• Rheumatic heart disease ^{[1] [2] [3] [4] [1][5]}
• Sometimes described are intravenous leiomyomatosis, ventriculoatrial shunts causing TS.^[6]
• Carcinoid syndrome^{[1] [7] [8] [9] [1]} </ref> ^[6]
• Benign tumors like atrial myxomas can cause functional TS^[10]. ^[11]

1. Tetralogy of fallot ^[16] Chronic turbulent flow through a deformed valve appears to cause these changes and as a result the valve looses it’s normal morphology.^{[17] [18] [19]}
2. Noonan syndrome
3. Leopard syndrome
4. William’s syndrome
5. Alagille syndrome
6. Congenital rubella syndrome

1. Carcinoid syndrome ^[20]
2. Rheumatic fever ^[21]
3. Homograft dysfunction^[22]
4. Pulmonary hypertension ^{[23] [24]}

Disease name] may be caused by [cause1], [cause2], or [cause3].

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List the causes of the disease in alphabetical order:

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Keri Shafer, M.D. [3]

Right ventricular outflow tract obstruction must be distinguished from an ASD, a small VSD, aortic stenosis, and acyanotic or pink tetralogy of Fallot.

Right ventricular outflow tract obstruction must be distinguished from several other conditions. ^[1]

1. Atrial septal defect: Also has a systolic ejection murmur, wide fixed split S2, EKG showing RVH. In ASD the split of the S2 is fixed, there is no ejection click. ^[2]

2. Small Ventricular septal defect: Amyl nitrate increases venous return and increases the murmur of pulmonary stenosis, in VSD the murmur becomes softer.

3. Mild left-sided outflow obstruction: With valsalva maneuver the murmur of aortic stenosis becomes softer after about 5 beats, with pulmonary stenosis it becomes softer within 3 beats.

4. Acyanotic or pink tetralogy of Fallot: with amyl nitrate and increased venous return the murmur of PS increases, and the murmur of tetralogy decreases because of peripheraldilation and an increase in right to left shunting. ^[3]

The differential diagnosis of aortic regurgitation includes other valvular abnormalities:^{[4][5][6][7][8][9]}

• Aortic stenosis: The murmur of aortic stenosis is harsh and best heard at the right second intercostal space.
• Mitral regurgitation: The murmur of mitral regurgitation is blowing, soft and best heard at the apex.
• Mitral stenosis: The murmur of mitral stenosis is mid-diastolic, rumbling, and best heard after the opening snap.
• Tricuspid regurgitation: The murmur of tricuspid regurgitation is blowing, holosystolic, and best heard over the fourth intercostal area at the left sternal border.
• Tricuspid stenosis: The murmur of tricuspid stenosis is characterized by a mid diastolic murmur best heard over the left sternal border with rumbling character and tricuspid opening snap with wide splitting of S1.

Aortic regurgitation should also be differentiated from other diseases that might cause similar clinical presentation, such as:^{[10][11][12][13]}

• Acute coronary syndrome
• Anemia
• Heart failure
• Infective endocarditis
• Patent ductus arteriosus
• Pregnancy
• Thyrotoxicosis
• Volume depletion
• Wet beriberi

Following are the cardiac conditions having similar presentation as Aortic regurgitation:^{[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]}

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Varun Kumar, M.B.B.S.

Isolated pulmonic valvular stenosis with intact ventricular septum is the second most common congenital cardiac defect.

Right ventricular outflow tract obstruction represents 8-12% of all congenital heart defects in children^[1][2] and 15% of all congenital heart defects in adults^[3][4][5]. Isolated pulmonic valvular stenosis with intact ventricular septum is the second most common congenital cardiac defect. ^{[6] [7]}

Right ventricular outflow tract obstruction secondary to rheumatic fever is rare and it seldom causes serious pulmonic valvular deformity. It usually may occur in association with the pulmonary hypertension that occurs at high altitudes. The prevalence of rheumatic disease in developed nations is steadily declining. Developing countries, in contrast, have higher rates of rheumatic fever and subsequent mitral stenosis with a prevalence of more than 10 cases per 1,000 in India and 4-10 cases per 1,000 in China, Russia, Africa and Australia. ^{[8] [9] [10]}.

Right ventricular outflow tract obstruction usually occurs in newborn. However, the age at presentation depends on the severity of the obstruction with many patients with mild obstruction presenting at adolescence or adulthood. ^{[9] [11]}

Prevalence of pulmonary stenosis does not differ significantly with race.^{[12] [8]}

Prevalence of right ventricular outflow tract is equal among males and females.^{[3] [7]}

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

The most common risk factor for the development of pulominic stenosis is the presence of a congenital bicuspid pulmonic valve. Risk factors that may speed up the progression of pulmonic stenosis include the same risk factors as atherosclerosis. ^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

If left untreated, [#]% of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].

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Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].

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Prognosis is generally excellent/good/poor, and the 1/5/10-year mortality/survival rate of patients with [disease name] is approximately [#]%.

Patients with congenital pulmonary stenosis manifest clinical features few hours after birth, in childhood or in adulthood. Manifestation of symptoms, symptom severity and the outcomes are dependent on the severity of stenosis.^[1] Patients with mild pulmonic stenosis have a benign course and do not progress and patients with moderate and severe stenosis have dyspnea with exertion and syncope.^[2]

If left untreated, patients with moderate to severe stenosis progress to develop tricuspid regurgitation and right ventricular dysfunction leading to right ventricular failure and arrhythmias.^[3]

Patients with moderate to severe pulmonic valve stenosis are managed well with surgery or balloon valvuloplasty and have very good prognosis. ^[4]

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