Partial Anomalous Pulmonary Venous Connection Workup

Updated: Dec 16, 2020
  • Author: Monesha Gupta, MD, MBBS, FAAP, FACC, FASE; Chief Editor: Stuart Berger, MD  more...
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Workup

Imaging Studies

Chest radiography

Cardiomegaly noted on chest radiography may be the initial reason for referral of a child with partial anomalous pulmonary venous connection (PAPVC). Other findings may include a dilated main pulmonary artery and increased pulmonary arterial vascular markings. However, chest radiography findings may be grossly normal.

Anomalous connection of one or more veins from the left lung into a left vertical vein that drains into the left innominate vein can create widening of the left upper mediastinal shadow. Rarely, the increased flow volume may also be sufficient to dilate the superior vena cava (SVC), widening the upper right mediastinal shadow. This can simulate the so-called "snowman" heart shape described in total anomalous pulmonary venous return to a left vertical vein.

In its classic appearance, scimitar syndrome causes the "scimitar sign." This sign is a linear opacity, usually (but not always) found at the base of the right lung, that widens as it courses inferiorly and ends in the inferior vena cava. It is associated with dextroposition of the heart due to right lung hypoplasia. The scimitar sign can be obscured by a significant dextropositioning of the heart.

Echocardiography

PAPVC has been diagnosed in utero. In children, echocardiography is the study of choice; however, the lesion can be easily missed if routine echocardiography does not incorporate definition of the entire pulmonary venous return. The size or the diameter of the pulmonary veins should be determined by 2-dimensional (2D) echocardiography. Spectral Doppler study of the individual pulmonary veins is also important to determine obstruction to the flow

In most patients, transthoracic echocardiography can be performed to diagnose PAPVC and obviate the need for cardiac catheterization. A high index of suspicion for the presence of the lesion is helpful to properly diagnose the condition.

In adults, contrast echocardiography can help with the diagnosis. Agitated saline in a left arm vein can reveal a negative contrast in the innominate vein at the side of the anomalous venous drainage from a left pulmonary vein.

Transesophageal echocardiography is also performed for better delineation of the veins, especially in the adult population.

Right ventricular dilation may be the first observation that indicates the presence of abnormal venous drainage. The sonographer must identify all 4 pulmonary veins and visualize their connections to the heart. The atrial septum also needs to be evaluated for defects.

Zhang et al evaluated the value of echocardiography in the diagnosis of anomalous pulmonary venous connections (APVCs) that were identified and confirmed by surgery or computed tomography angiography (CTA). Of 84 cases, 51 were total anomalous pulmonary venous connections (TAPVCs) and 33 were partial anomalous pulmonary venous connections (PAPVCs). The sensitivity of echocardiography in the diagnosis of APVCs was 97.6%, and the echocardiography misdiagnoses were primarily observed in PAPVCs. Of the PAPVCs that were correctly diagnosed by echocardiography, the diagnostic accuracy of classification was 100%. [4]

Magnetic resonance imaging

Magnetic resonance imaging (MRI) is rapidly becoming the procedure of choice for further investigation of PAPVC. [5] Although echocardiography findings suggest the PAPVC, all the pulmonary veins may not be identified, especially in adults. With refinements in technology rapidly improving the quality of images obtained, fewer children require invasive angiography. Cardiac catheterization may be a more preferable diagnostic tool in infants with complex congenital heart conditions in whom PAPVC is one component.

Julsrud and Ehman reported that use of MRI in the imaging of PAPVC revealed a characteristic sign termed the "broken ring sign." [6] In individuals with normal anatomy, a transverse MRI demonstrates a ringlike structure derived from mediastinal fat that surrounds the SVC. In healthy individuals, this ring is broken only at the point of entry of the azygous vein into the SVC. In some patients with partial anomalous pulmonary venous return, the ring of fat also appears to be breached or broken at the site of entry of the anomalous vein.

Computed tomography scanning

Contrast-enhanced computed tomography (CT) scanning is an alternative imaging modality to detect PAPVC when transthoracic images are limited, especially in older children and adults. Multislice CT scanning is useful in preoperative planning. [7]

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Other Tests

Electrocardiogram

Electrocardiography (ECG) findings may be normal in partial anomalous pulmonary venous connection (PAPVC). They may demonstrate right ventricular dilation manifested by an rSR pattern in right chest leads or right ventricular hypertrophy.

Right atrial dilatation may be observed with a P pulmonale on ECG.

Postoperative sinus node dysfunction can occur due to damage to the sinus node or its blood supply. This can manifest as significant bradycardia or junctional rhythm or sinus pauses of 3 seconds or more in duration.

Arrhythmias, typically supraventricular tachycardia, atrial flutter, and fibrillation, may be observed, either due to right atrial enlargement at older age or secondary to atriotomy and sutures.

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Procedures

Cardiac catheterization is rarely necessary for precise anatomic diagnosis and hemodynamic evaluation in the workup of partial anomalous pulmonary venous connection (PAPVC). Right heart pressures are normal in the pediatric patient. Oxygen sampling may identify the location of an anomalous vein. Oxygen saturation in the right atrium that is higher than that found in the SVC strongly indicates PAPVC to the right atrium, provided that an atrial septal defect (ASD) has been ruled out. Qp:Qs can be calculated.

Entering the anomalous vein with a catheter and injecting contrast confirms the diagnosis. Selective right and left pulmonary artery angiography that reveals pulmonary venous return for each lobe from each lung provides definitive anatomic diagnosis. Complications of catheterization include bleeding at the vascular entry site, infection, decreased pulses distal to an arterial entry site, and arrhythmia induction.

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