Total Anomalous Pulmonary Venous Return
Definition
The pulmonary veins which carry the blood back to left heart after it has circulated through the lungs are not connected to the left atrium. Instead, they are connected to one of the veins from the main circulation so that the blood returning from the lungs drains back to the right side of the heart. In this form of defect, the blood returning from the lungs returns through the inferior vena cava, and is often obstructed, leading to the early onset of severe symptoms.
There are three types of TAPVR:
Type I - supracardiac, connection is above the diaphragm, either left branchiocephalic vein or superior vena cava.
Type II - cardiac, connection is either at coronary sinus or right atrium.
Type III -infracardiac, the connection is below the diaphragm, a common trnk originates from the confluence of pulmonary veins and descends in front of the esophagus, penetrating the diaphragm through the esophageal hiatus.
Pathology
This anomalous connection results in a mixture of systemic and pulmonary venous blood with higher oxygen saturations beyond the point of abnormal pulmonary return. Patent foramen ovale (PFO), ASD, and PDA are necessary for survival. They are needed for the blood to pass from right to left and a variable degree of systemic artery desaturation is present and depends upon the degree of pulmonary vascular resistance. The patient is more cyanotic if the venous return is impeded, which usually occurs in infracardiac connections. Patients with TAPVR have both right to left shunt at the atrial level, and left to right shunt as the pulmonary venous return recirculates through the lungs.
Clinical Manifestaions
Many patients present with only mild cyanosis (such as in supracardiac return). Infracardiac return usually presents with significant cyanosis in the newborn.
Two types of symptoms:
1. Normal pulmonary pressures - congestive heart failure (CHF) will occur in 50% of patients within 10-15 months, hepatomegaly will usually develop secondary to CHF, a systolic murmur will be heard.
2. Pulmonary hypertension - moderate to severe cyanosis at birth, early and more severe appearence of CHF, elevation of jugular venous pressures, systoluc murmur wuth palpable pulmonary artery if pressure exceeds 60 mm Hg, higher mortality associated.
Surgical Interventions
Surgical treatment is indicated if pulmonary hypertension exists and, if performed early, the survival rate is greater than 75 %. If no CHF is present and pulmonary pressures are normal surgical correction can be safely delayed for several years.
Surgery usually implies the return of pulmonary venous return to the left side of the heart, and repair of PDA, ASD, and patent foramen ovale.
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