Cardiac > Congenital > PAPVR

Partial Anomalous Pulmonary Venous Return:

Clinical:

Partial anomalous pulmonary venous return (PAPVR) is more common than the total variety with an overall incidence of about 0.5% [4]. PAPVR  results in an extra-cardiac left-to-right shunt, however, the shunt is usually hemodynamically insignificant [4]. Symptoms do not generally occur unless 50% or more of the pulmonary flow is shifted from left to right (i.e.: a shunt ratio of pulmonary blood flow to systemic blood flow of greater than or equal to 1.5 [5]). Patients with PAPVR are usually older at presentation [5].

The right lung is more frequently affected than the left [4]. Drainage of the right upper lobe pulmonary vein directly into the SVC or right atrium is the most common type of partial anomalous PAPVR [5] and this is generally of no clinical significance, although there is a high prevalence of an associated sinus venosus ASD (located high in the septum near the SVC orifice [4,6]). Because this type of ASD is usually clinically silent, the associated PAPVR may be the clue leading to the diagnosis [6]. Some authors suggest that right upper lobe PAPVR is associated with a sinus venous ASD in 80-90% of pediatric patients, and 47% of adults [7].

Approximately one-third of patients with PAPVR have anomalous left pulmonary veins. In LUL PAPVR a verticle vein drains from the medial aspect of the left upper lobe into the left brachiocephalic vein. LUL PAPVR may be confused with a persistent left SVC- however, no connection to the coronary sinus will be seen and the left superior intercostal vein will not connect to the verticle vein associated with LUL PAPVR. Phase contrast MR images can also be used to demonstrate cephalic flow in the ventricle vein and caudal flow in the persistent SVC. [1]

Scimitar Syndrome (Pulmonary venolobar syndrome): Scimitar syndrome is due to a partial anomalous pulmonary venous return and patients are generally asymptomatic. The disorder is usually seen on the right side and can be identified as a "Scimitar" shaped vein crosses the lung. This vein usually drains to the IVC and the lung on the involved side is characteristically hypoplastic (as this is usually the right side there is a compensatory dextroposition of the heart). The pulmonary artery to the involved lung is also generally small or absent. Scimitar syndrome is associated with an accessory right hemidiaphragm (which can be identified as an increased retrosternal density). Ostium secundum atrial septal defects are usually present in association with PAPVR to the IVC [2].

REFERENCES:

(1) Radiographics 1997; MR imaging of congenital anomalies of the thoracic veins. 17: 595-608

(2) Seminars in Roentgenology 1989; Budorick NE, et al. The pulmonary veins. 24 (2) Apr: 127-149

(3) AJR 2000; Klecker RJ, et al. Vertical vein (Partial anomalous pulmonary venous drainage). 175: 869-870

(4) AJR 2004; Demos TC, et al. Venous anomalies of the thorax. 182: 1139-1150

(5) Radiographics 2012; Vyas HV, et al. MR imaging and CT evaluation of congenital pulmonary vein abnormalities in neonates and infants. 32: 87-98

(6) Radiographics 2013; Porres DV, et al. Learning from the pulmonary veins. 33: 999-1022

(7) Radiographics 2015; Sonavane SK, et al. Comprehensive imaging review of the superior vena cava. 35: 1873-1892

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