Rush Center for Congenital
and Structural Heart Disease

Definition

 

   

 

Incidence

 

This is the 10th most common congenital heart disease amongst neonates. It is the 23rd most common congenital heart disease. It occurs in 0.07/1,000 live births.  

 

 

Embryology

 

The following facts support that this is most probably an acquired disease in utero rather than an aberration of development:

  • Well formed pulmonary valve leaflets.
  • Size of pulmonary arteries.
  • Variable RV size.
  • Rarity of associated lesions.
 
 

 

 

Pathology

 

The pulmonary valve annulus is usually small but not hypoplastic. The pulmonary valve leaflets are well formed but fused. The main pulmonary artery is small but rarely is atretic as seen with pulmonary atresia and ventricular septal defect. The patent ductus arteriosus is usually small because it carries blood from aorta to pulmonary arteries in utero and not the other way around as in normal. Therefore, much less blood travels through the PDA in utero. The right ventricle might be of several types.

Type I is tripartite.

Type II bipartite (atretic body).

Type III unipartite (atretic body and infundibulum).

Tricuspid valve might be deformed and stenotic.

Sinus nodes from the right ventricle cavity to myocardium and from myocardium to coronary arteries. Collateral circulation from the descending aorta to pulmonary arteries is rare. Other congenital heart disease is rarely associated with this one. Right aortic arch is not known to occur in pulmonary atresia with intact ventricular septum.

 
 

 

 

Pathophysiology

 

Egress of blood determines right ventricular pressure and size. The more egress through the tricuspid valve into the right atrium or sinus into coronary arteries the less is the RV pressure. The more the TR , the larger the right ventricle and right atrial sizes. The venous return will go from right atrium predominantly through a patent foramen ovale to the left atrium causing cyanosis. The patent foramen ovale will be restrictive but the pressure gradient is rarely more than 2-3 mm Hg. Children develop cyanosis after birth and a systolic murmur secondary to tricuspid regurgitation.  

 

 

Clinical Manifestations

 

At birth the ductus arteriosus provide pulmonary blood flow and there may or may not be cyanosis evident in the immediate neonatal period. As the ductus arteriosus close, there will be less pulmonary blood flow causing cyanosis.

Physical findings will be consistent with cyanosis, PDA murmur and a single second heart sound.

 
 

 

 

ECG

 

 
Leftward axis in 77% will have 0-90 degrees QRS axis. This is due to absence of right ventricular predominance as is normally seen. Right axis deviation is seen in patients with pulmonary atresia and ventricular septal defect and with severe TR causing the RV to be dilated. In tricuspid atresia 16% have less than 0 degree QRS axis while in pulmonary atresia with ventricular septal defects 70% have more than 90 degrees QRS axis.

 

 

CXR

 

The chest x-ray shows a small cardiac silhouette.  However, in the presence of free tricuspid regurgitation there will be severe cardiomegaly which may lead to poor lung development as in patients with diaphragmatic hernias.  

 

 

Echocardiography

 

Pulmonary blood flow is supplied through the patent ductus arteriosus. The valve leaflets are fused and there is variable hypoplasia of the right ventricle. The main pulmonary artery tends to be well developed and the PDA is usually tortuous and siphon shaped. The diameter of the tricuspid regurgitation obtained by color Doppler and size of the right atrium are good indicators of the severity of tricuspid regurgitation.  

 

 

Cardiac Catheterization

 

Rashkind atrial septostomy may be needed to allow right to left shunting across the atrial septum.  Cardiac catheterization is indicated in all cases to assess pulmonary arterial anatomy as well as coronary arterial to RV fistula.  

 

 

Treatment

 

Prostaglandin E infusion is started to keep the ductus arteriosus open to provide pulmonary blood flow. Surgical pulmonary valvotomy with or without systemic to pulmonary arterial shunt depending upon the RV size. If the RV is small a systemic to pulmonary arterial shunt will be necessary to provide pulmonary blood flow until antegrade flow through the pulmonary valve is adequate. However, if the pulmonary arteries are not small then pulmonary valvotomy alone may be adequate.

Decompression of the artery by pulmonary valvotomy may cause reversal of flow in coronary artery to artery sinus nodes leading to poor myocardial perfusion. This is especially true with coronary artery stenosis. Therefore, right ventricular decompression should not be performed if coronary arterial stenosis is noted with sinus sites. In patients with small pulmonary arteries and placement of the systemic to pulmonary arterial shunt if the RV continues to be small and inadequate than a Fontan procedure may be performed. Patients with severe coronary to RV fistula may require cardiac transplantation. Sinuses are typically not present in patients with severe tricuspid insufficiency and a normal right ventricular size. In patients with significant tricuspid insufficiency and low RV pressure valvotomy may not result in effective forward flow through the right ventricle because of the tricuspid insufficiency.

 
 

 

 

Course and Prognosis

 

   

 

 

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