Pulmonaryatresia intact ventricular septum

Pulmonary Atresia with Intact Ventricular Septum (PA-IVS) is a rare congenital heart defect characterized by the underdevelopment or absence of the pulmonary valve, which is responsible for controlling blood flow from the right ventricle of the heart to the lungs. In PA-IVS, the ventricular septum—the wall separating the left and right ventricles—is intact, meaning there is no hole between the ventricles, which is a condition that distinguishes it from other types of congenital heart defects.

Etiology

The exact cause of Pulmonary Atresia with Intact Ventricular Septum is unknown. However, it is believed to be a result of abnormal development of the fetal heart during the first eight weeks of pregnancy. Genetic factors and environmental influences may play a role, but specific causes have yet to be identified.

Pathophysiology

In PA-IVS, blood cannot flow directly from the right ventricle to the lungs because the pulmonary valve is either completely closed or severely underdeveloped. This obstruction forces the heart to find alternative pathways to oxygenate the blood. The right ventricle may become hypertrophied (thickened) due to the increased effort required to pump blood. Blood typically bypasses the nonfunctional pulmonary valve through a patent ductus arteriosus or collateral arteries that develop to connect the pulmonary and systemic circulations.

Clinical Presentation

Symptoms of PA-IVS may vary depending on the severity of the condition and the presence of associated heart defects. Common signs include cyanosis (a bluish tint to the skin, lips, and nails), difficulty breathing, and feeding problems. Infants with this condition may also exhibit signs of heart failure such as rapid breathing, excessive sweating, and poor weight gain.

Diagnosis

Diagnosis of PA-IVS typically involves a combination of physical examination, echocardiography, and cardiac MRI. Echocardiography is the primary diagnostic tool used to visualize the structure and function of the heart, confirming the presence of an intact ventricular septum and the absence or underdevelopment of the pulmonary valve.

Treatment

Treatment for PA-IVS is aimed at improving blood flow to the lungs and may include both surgical and non-surgical interventions. Initial treatment often involves the administration of prostaglandin E1 to keep the ductus arteriosus open, allowing for some blood flow to the lungs. Surgical options may include the creation of a shunt to bypass the atretic pulmonary valve, balloon valvuloplasty to open the pulmonary valve (if present), or, in severe cases, the construction of a complete Fontan circulation to direct blood flow from the right atrium to the pulmonary arteries, bypassing the right ventricle entirely.

Prognosis

The prognosis for individuals with PA-IVS varies widely and depends on the severity of the condition, the presence of additional heart defects, and the success of interventions. Advances in surgical techniques and postoperative care have significantly improved outcomes, allowing many affected individuals to lead active lives.

See Also

• Congenital heart defect
• Cyanotic heart defect
• Fontan procedure