Pulmonary Atresia And Pulmonary Stenosis

Miroslav Elek
Pediatrician, East Sarajevo Hospital Bosnia and Herzegovina
First Created: 02/05/2001  Last Updated: 05/14/2016

Pulmonary Atresia and Pulmonary Stenosis - Introduction

Pulmonary atresia (PA) is hypoplasia and complete closure of the outflow part of the right ventricle and/or pulmonary artery and the crucial factor for the primary presentation and prognosis is the existence or non-existence of patent ductus arteriosis (PDA). It can be with or without ventricular septal defect (VSD).

Pulmonary stenosis (PS) is the narrowing of one or more parts from the outflow tract of the right ventricle to the pulmonary artery. The most common is pulmonary valvar stenosis and it is classified according to pressure gradient as trivial (= 20 mmHg), mild (21-40 mmHg), moderate (41-70 mmHg), and severe (>70 mmHg). Pulmonary stenosis can be associated with some of the syndromes such as Noonan, Williams, Alagile, and others. The incidence of obstructive congenital defects of the pulmonary artery among other congenital heart defects is about 7-10%. Genetic, environmental, and familial factors are included in the multifactorial etiology of pulmonary atresia and stenosis.

Pulmonary Atresia and Pulmonary Stenosis - Presentation

Pulmonary atresia with a ventricular septal defect is synonymous with an extreme form of Tetralogy of Fallot and Type IV truncus arteriosus or psueudotruncus. The amount of pulmonary blood supply makes a difference in treatment and outcome. Pulmonary circulation is provided by PDA, bronchial arteries, and aortopulmonary collaterals. Newborns with PA and VSD are good in the first hours of life until ductus arteriosus closes. Then occurs hypoxemia, cyanosis, acidosis, and signs of respiratory distress and heart failure.

PA with the intact interventricular septum (IVS) is a very rare congenital heart defect and it presents in the first hours of life with tachypnea and cyanosis of the newborn. Blood from the right ventricle has no way out except retrograde flow through the tricuspid valve. Often can be found communication between the right ventricle and coronary vessels, through the persistent myocardial sinuses.

Mild and moderate pulmonary stenosis can be asymptomatic for a long time. Severe or critical stenosis manifests with cyanosis, tachypnea, exercise intolerance, arrhythmias, and signs of right heart failure (hepatomegaly, ascites, edema, neck veins distension). In older children can occur exercise-induced syncope and symptoms similar to those of ischemic heart disease.

Pulmonary Atresia and Pulmonary Stenosis - Investigations

In physical exam in PA with VSD by auscultation, we find a heart murmur of PDA and collateral vessels, second heart tone is monocomponent. The heart is „clog“ shaped on X-ray with unequal pulmonary vascularization in different parts of the lungs. ECG shows right ventricle hypertrophy and right axis deviation. In newborns with PA with IVS, there is a heart murmur of tricuspid regurgitation and monocomponent first and second heart tone. On X-ray, there is a slightly enlarged heart, and reduced pulmonary vascularisation. On ECG there is left ventricle domination. Echocardiography is the gold standard in the diagnosis and evaluation of pulmonary atresia. Angiography can also be performed.

In pulmonary stenosis dominant clinical sign is a heart murmur and weakened second pulmonary heart tone. ECG shows right ventricle hypertrophy and right axis deviation. On X-ray, we can see post stenotic dilatation of the pulmonary artery. The final diagnosis is confirmed by echocardiography. An echocardiographic exam is necessary for assessment of the severity of stenosis based on pressure gradient, also for the assessment of pulmonary valve morphology, right ventricle hypertrophy, and associated heart defects. Heart catheterization and angiography can be performed for the re-measurement of pressure gradients and detecting peripheral pulmonary stenosis.

Treatment and Prognosis

If there is a suspected "ductus dependent" pulmonary circulation first step can be an infusion of prostaglandin (PGE1) for keeping ductus arteriosus patent. The next step is surgical or transcatheter perforation of the pulmonary valve, stent placement in ductus arteriosus, or creation of a modified Blalock Taussig shunt. If possible complete surgical correction is performed. What makes surgical correction difficult is the existence of major aortopulmonary collateral arteries (MAPCAs), also small and very hypertrophic right ventricle and distal pulmonary stenosis. Newborns with cyanosis and developing heart failure without palliative interventions have a very high mortality rate.

Treatment for children with moderate and severe pulmonary stenosis is transluminal balloon dilatation and stent placement, and if necessary and possible surgical reparation.

Authors report that a mild pulmonary stenosis pressure gradient in children above 1 year of age will not increase with time and that there is even a possibility to decrease, while in other groups of patients with severe stenosis pressure gradient actually increases. The most important is adequate follow-up and well-timed clinical management of these patients, in the individual estimated time intervals based mostly on pressure gradient and clinical manifestations.

1. Pulmonary atresia with ventricular septal defect: Systematic review, D. Balaguru et al.
2. Pulmonary atresia with intact ventricular septum: Menagement options and decision-making, H. Burkholder et al.
3. Does mild pulmonary stenosis progress during childhood? A study of its natural course, J Ardura et al.

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