Meandering Right Pulmonary Vein to the Left Atrium and Inferior Vena Cava

Abstract

We report a case of a healthy, asymptomatic 6-year-old boy in whom an anomalous right pulmonary vein was noted to drain into both the inferior vena cava and left atrium in association with findings consistent with scimitar syndrome. The anomalous pulmonary vein took a very circuitous route through the lungs before draining into the left atrium, a condition previously termed “meandering pulmonary vein.” To aid in the diagnosis, cardiovascular magnetic resonance imaging and magnetic resonance angiography were used to delineate this complex course and the connection of the anomalous pulmonary vein. To our knowledge, this is the 1st reported case of a meandering pulmonary vein with dual drainage to the inferior vena cava and left atrium in association with other anomalies. (Tex Heart Inst J 2002;29:319–23)

There have been rare reports in the literature of patients with an anomalous pulmonary vein that follows a circuitous route through the lungs before draining into the left atrium, a condition termed meandering pulmonary vein by Goodman and colleagues. ¹ This anomaly has been described both as an isolated finding ^2–5 and in association with scimitar syndrome. ^1,6–7 Rare cases of a meandering pulmonary vein with dual drainage to both the left atrium and the inferior vena cava (IVC) have also been reported, ^2,8 but none of these cases has occurred in association with other cardiac or vascular anomalies (Table I ^1–8).

TABLE I. Cases of Meandering Pulmonary Vein Reported to Date

We report an interesting case of a healthy, asymptomatic 6-year-old boy in whom a meandering pulmonary vein drained to both the left atrium and the IVC in association with scimitar syndrome. To our knowledge, this is the 1st such case reported in the English literature.

Case Report

A 6-year-old boy was referred to the cardiology clinic at Texas Children's Hospital for evaluation of an abnormal shadow seen on a chest radiograph that had been performed at an outside facility during an evaluation for migraine headaches. He had no symptoms referable to the cardiovascular system, and had experienced normal growth and development. The patient's medical history was significant for frequent episodes of otitis media and mild upper respiratory infections during infancy, but there had been no hospitalizations except for his recent admission for migraine headaches.

Physical examination was unremarkable except for a grade 1–2/6 systolic ejection murmur that was vibratory in quality and heard best along the left sternal border. A frontal chest radiograph revealed mesocardia (rather than dextroposition of the heart), a right-lung volume smaller than that of the left, and a crescent-shaped shadow along the superolateral aspect of the right-heart border (Fig. 1A). A surface electrocardiogram showed a low right-atrial rhythm and a nonspecific interventricular conduction delay. Two-dimensional and Doppler echocardiography revealed mesocardia, no intracardiac structural abnormalities, mild right ventricular dilatation, and at least 2 pulmonary veins returning to the left atrium. The presence of a partial anomalous pulmonary venous connection could not be ruled out.

Fig. 1 A) Posteroanterior chest radiograph shows mesocardia with a prominent right-heart border; a circular shadow (arrow) at the superolateral aspect of the upper right-heart border represents the meandering pulmonary vein as it courses back to the left atrium. B) This posteroanterior chest radiograph shows an anomalous vessel (arrow) coursing down the right-heart border. It resembles the Turkish sword called a scimitar.

Cardiac magnetic resonance imaging (MRI) was performed to better delineate the pulmonary venous anatomy. Three-dimensional contrast-enhanced magnetic resonance angiography (CE-MRA) and cine MRI revealed an enlarged right lower pulmonary vein that had an extremely unusual course with communications leading to both the left atrium and the IVC. The pulmonary vein communicated with the systemic venous return at the confluence of the IVC and the hepatic veins. This connection appeared to be small and possibly stenotic (Fig. 2 ⁹). The anomalous right lower pulmonary vein also communicated with the right upper pulmonary vein just before entering the left atrium. The common right pulmonary vein drained into the left atrium without obstruction (Fig. 3 ⁹). Also noted upon CE-MRA was an abnormal collateral artery that arose from the celiac artery of the abdominal aorta and supplied the posterior-medial portion of the right lower lobe (Fig. 4).

Fig. 2 Sagittal frames from multislice cine MRI study of patient, reformatted with local maximal intensity projection. A) Rightward positioned section. White arrow indicates position of anomalous right lower pulmonary vein. B) Medially positioned section. White arrow indicates position of anomalous right lower pulmonary vein. Note that the right lower pulmonary vein has a small communication with the inferior vena cava.

A = anterior; I = inferior; MRI = magnetic resonance imaging; P = posterior; S = superior

Fig. 3 Coronal frames from multislice cine MRI study of patient, reformatted with local maximal intensity projection. A) Posteriorly positioned section. White arrow indicates position of anomalous right lower pulmonary vein. B) Anteriorly positioned section. White arrow indicates position of anomalous right lower pulmonary vein. Note the common right pulmonary vein draining into the left atrium.

I = inferior; L = left; MRI = magnetic resonance imaging; R = right; S = superior

Fig. 4 Maximal intensity projections of 3-dimensional contrast-enhanced MRA study of patient with sensivity encoding (SENSE) technique. A) White arrow indicates position of the anomalous right lower pulmonary vein. B) White arrow indicates position of the anomalous artery that originates from the abdominal aorta and supplies the right lower lobe.

I = inferior; L = left; MRA = magnetic resonance angiography; R = right; S = superior

The patient was referred for cardiac catheterization to better delineate the anomalous pulmonary venous return from the right lung and the abnormal arterial supply to the right lower lobe. Transcatheter occlusion of the abnormal artery was to be performed if indicated. Prograde right-heart and retrograde left-heart catheterizations revealed normal right-heart pressures and no intracardiac shunting. Pulmonary angiography demonstrated a normal-sized left pulmonary artery (13.0-mm diameter), normal arborization pattern to the left lung, and normal left pulmonary venous drainage into the left atrium. There was mild hypoplasia of the right pulmonary artery, which measured 9.6 mm in diameter. Angiograms of the right lower pulmonary artery wedge confirmed a large, right lower lobe pulmonary vein that followed a circuitous route through the right lung before draining into the left atrium. The right lower pulmonary vein also drained into the IVC via a small communication that appeared to be stenotic (1.6 mm in diameter) at its entrance to the IVC just above the hepatic veins. Angiography in the thoracic and abdominal aorta demonstrated an anomalous systemic artery, which arose from the celiac trunk and coursed to a posteromedial segment of the right lower lobe. Simultaneous injections into the right pulmonary artery and the anomalous arterial vessel off the celiac trunk confirmed that this segment of the right lower lobe was not perfused by the right pulmonary artery but only by the subdiaphragmatic anomalous systemic artery (Fig. 5).

Fig. 5 Simultaneous angiograms are performed in the anteroposterior projection into the right pulmonary artery (RPA) and systemic collateral artery. A portion of the medial-basal and posterior-basal segment of the right lower lobe perfused by the collateral vessel does not have dual supply from the right pulmonary arterial system.

Because the patient remained asymptomatic, he was discharged home from the hospital, with periodic clinical follow-up for management of his condition.

Discussion

Scimitar syndrome is a rare anomaly that consists of 4 findings: 1) hypoplasia of the right lung with dextroposition of the heart, 2) hypoplasia of the right pulmonary artery, 3) anomalous pulmonary venous connection of the right lung to the inferior vena cava, and 4) anomalous arterial supply of the right lower lobe from the abdominal aorta. ¹⁰ The “scimitar sign” ¹¹ is a characteristic radiographic finding often seen in patients with scimitar syndrome. The anomalous right pulmonary venous connection to the IVC forms a shadow along the right-heart border that is similar in shape to a Turkish sword (Fig. 1B). Although the scimitar sign is an important diagnostic finding, it is not specific for the diagnosis of scimitar syndrome. ² In fact, Goodman and colleagues ¹ reported a case in which a scimitar sign on chest radiography was associated with an anomalous pulmonary vein that coursed circuitously through the right lung before draining into the left atrium, an anomaly that the authors termed meandering pulmonary vein. Other variants of scimitar syndrome have also been described, including the finding of the scimitar sign associated with normal pulmonary venous drainage and systemic arterial supply. ^6,7

Cardiac catheterization has typically been used to confirm the diagnosis of scimitar syndrome or of other anomalous pulmonary venous connections when the diagnosis has been suspected on routine chest radiography and has not been demonstrable by echocardiography. Indeed, the diagnostic gold standard for scimitar syndrome has been angiography. In most cases, it is possible to catheterize the aberrant right pulmonary vein directly from the IVC using a prograde approach, as we were able to do in our patient. Angiography of the right ventricle or pulmonary arteries can also confirm the findings of hypoplastic right pulmonary artery and anomalous venous drainage of the right lung. Descending aortography is used to delineate any abnormal systemic arterial supply to the right lower lobe, which is a form of vascular sequestration.

Recently, noninvasive diagnostic techniques such as computed tomography (CT) and CE-MRA have been used as an adjunct to cardiac catheterization in the diagnosis of the scimitar syndrome ^12–15 or to the evaluation of other vascular anomalies. Three-dimensional CE-MRA or cine MRI, alone or in combination, offers the advantage of a noninvasive procedure that does not expose the patient to ionizing radiation, yet enables a comprehensive evaluation of the vascular anatomy in such patients. In the present case, all of the abnormal vascular findings shown by angiography, including the complex venous abnormalities, were accurately demonstrated by MRI and MRA before catheterization. Not only were the associated findings of scimitar syndrome all demonstrated by MRI and MRA, but the meandering pulmonary vein with dual drainage into the IVC and left atrium was also nicely visualized.

There have been no reports of a patient in whom an isolated meandering pulmonary vein produced symptoms or required surgical intervention. However, when such an anomaly is associated with scimitar syndrome, surgical intervention may be necessary. The surgical management of scimitar syndrome is somewhat controversial and is determined primarily by the patient's symptoms. The age at which symptoms become manifest can range from infancy to adulthood, and the clinical presentation can vary widely. ¹⁶ Infants may present with signs of volume overload of the right heart or congestive heart failure due to the obligatory left-to-right shunt. They may also present with recurrent respiratory symptoms secondary to bronchiectasis or with evidence of pulmonary hypertension. Adults, on the other hand, generally present with minor symptoms or remain asymptomatic. Surgical intervention to redirect the anomalous pulmonary venous return back to the left atrium may be required in patients with a significant left-to-right shunt. Lung resection has been required in patients with bronchiectasis, hemoptysis, or chronic parenchymal lung disease secondary to the abnormal arterial supply to the right lower lobe. ¹⁰

In our patient, there was no significant left-to-right shunting as indicated by saturation data or by angiography. This was thought to be a consequence of the stenotic entrance of the right pulmonary venous connection to the IVC and of the dual drainage of the anomalous vein into the left atrium, which enabled preferential venous return to the left atrium. The possibility of coil embolization of the anomalous artery that supplied the right lower lobe was considered before the catheterization; however, this was not performed because the patient remained asymptomatic. Clinical follow-up with periodic evaluations was the chosen management plan for our patient.

To the best of our knowledge, this is the 1st reported case of a meandering pulmonary vein draining into both the left atrium and the IVC with associated anomalies consistent with scimitar syndrome. This case illustrates that although routine chest radiography and echocardiography may suggest pulmonary venous anomalies, further evaluation is required to clearly delineate the course and connections of anomalous pulmonary veins. Historically, cardiac catheterization and angiography have been used primarily to aid in the delineation of meandering pulmonary veins or anomalous pulmonary venous connections and findings associated with scimitar syndrome. The present case shows that cardiovascular MRI or MRA can accurately delineate even the most complex courses and connections of anomalous pulmonary veins.