Pulmonary Atresia
Definition
Pulmonary atresia is a rare congenital heart defect that usually presents itself along with other malformations such as VSD, tricuspid atresia, or complete transposition of the great arteries.
Pulmonary atresia is the failure of the pulmonary valve to develop with the normal development of the right ventricular chamber. Arterial pulmonary atresia is the failure of the development of the main pulmonary artery, pulmonary valve, or the right ventricular chamber. Normal right heart circulation is not possible. Circulation depends on the patent foramen ovale or ASD and a PDA.
Pathology
When an ASD is present in pulmonary atresia blood will pass from the right atrium to the left atrium with the mixture of the venous and arteria blood moving towards the peripheral circulation. The mixed blood will move toward the left ventricle and the aorta. Then, a portion of the blood will continue along the aorta and a portion will move through the PDA, enter the pulmonary artery and then the lungs. The size of the PDA becomes very important with regards to the clinical manifestations of cyanosis and clubbing, where the increased size will decrease both manifestations.
Hemodynamics
Possible occurance of thrombosis in the RV cavity, lower oxygen saturations in the RV than in the other three chambers, enlargement of the ascending aorta is normal, marked elevation of the systolic pressure in the right ventricle, arterial oxygen saturations of 60% are not uncommon.
Clinical Manifestations
Common findings in pilmonary atresia are severe cyanosis (due to the mixture of venous and arteria blood and a possibility of a closed PDA), clubbing (due to decreased oxygen to the extremeties), dyspnea, RA hypertrophy, either a small or hypertrophic RV, inability at the time of cardiac cath to move from RV to PA, tachypnea, moderate enlargement of the cardiac silhoutte is seen in the X-ray.
Surgical and Medical Inteventions
Medical treatment is geared toward the treatment or prevention of bacterial endocarditis, cyanosis, and ischemia to the brain. It is important to keep ductus arteriosus patent since it it the main blood flow tract to the lungs (this may be achieved by the use of prostaglandins).
Surgical treatment depends upon the development of the right ventricle. If the RV chamber is normal or near normal in size, and the pulmonary artery is also normal, then a pulmonary valvulotomy may be performed alond with the closure of the ductus arteriosus and/or ASD or PFO. Mortality may exceed 50%. If the RV is hypoplastic with a normal pulmonary artery the surgical procedure is usually directed towards increasing pulmonary blood flow. If the main pulmonary artery is hypoplastic, the Fontan procedure is an effective method of repair.
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