Left partial anomalous pulmonary venous connection (PAPVC), a rare pulmonary venous variant

Abstract

A left partial anomalous vein connection and connection between left upper pulmonary vein and left internal thoracic vein was discovered in a 71-year-old man, with no history of previous cardiac surgery or an atrial septal defect, underwent a thorax HRCT scan without contrast media, following a chest x-ray, due to repeated bouts of smoking-related bronchitis. Left partial anomalous pulmonary vein connection is a rare venous variant, which more commonly affects the right side, resulting in a left to right shunt [9].

Introduction

Left partial anomalous pulmonary vein connection (PAPVC), usually asymptomatic, is a rare vascular variant, where the left upper pulmonary vein drains into systemic circulation (left brachiocephalic vein). The physiology and the normal anatomy are affected by the number partial anomalous vein connection (PAPVC) shunts. Moreover, looking at a single PAPVC in a series the shunt is modest when associated with mild dilatation of the left ventricle. The left upper pulmonary vein is seen laterally to the aorta and anteriorly to the left main bronchus. This anomalous venous connection can be mistaken for a double superior vena cava but in this case only one vein is seen at the level of the left hilum [2].

Case report

A 71-year-old man, with no history of previous cardiac surgery or an atrial septal defect (ASD) who suffered repeated bouts of smoking-related bronchitis, was sent by his general practitioner to undergo a thorax HRCT scan without contrast media following a chest x-ray. Bilateral interstitial thickening associated with an increased lung hilum was discovered (Fig. 5). A connection between the left upper pulmonary vein and the left brachiocephalic (Fig. 1) and the left internal thoracic veins (Fig. 2a-c) were discovered. After which no therapy was deemed necessary.

Fig. 5.

(a, b) Chest x-ray. Bilateral interstitial thickening associated with increased lung hilum (Courtesy of G. De Paula).

Fig. 1.

Coronal view of left partial anomalous pulmonary vein connection.

Fig. 2.

(a-c) Connection between left superior pulmonary vein and internal thoracic vein.

Discussion

The left PAPVC belongs to a broad spectrum of congenital anomalies resulting in a left to right shunt [9] following failure of fusion of embryological pulmonary veins into the left atrium. The overall incidence is estimated between 0,4 and 0,7%. The right side is more commonly affected, whereas the left side is affected up to 18,2% [2,7].

This anomalous pulmonary venous drainage, commonly diagnosed by angioCT, can also be diagnosed by transesophageal echocardiography [1,8].

Patients often have no specific cardiac or respiratory symptoms therefore a chest x-ray test is the first step [2] but an association with hemoptysis is possible [6]. There is a frequent association with ASD and PAPVC in 80%-90% of cases [10] which further increases the volume of left to right shunt with an increase of the likelihood of pulmonary hypertension [5]. If present ,ASD is asymptomatic when small in size. The morphology varies from an oval, circular, or even complex shape [9]. An intact atrial septum is extremely rare [10].

In our case the anomalous left superior pulmonary vein (15 mm) is bigger than the azygos vein (11 mm). The 2 diameters were evaluated at the connection between the azygos vein and the superior vena cava (Fig. 3). Moreover, the angle between the left pulmonary superior vein and the left brachiocephalic vein is estimated at 111° (Fig. 4). In actual fact, we think the difference may depend on the angle degree at the venous confluence. This angle had never been evaluated previously.

Fig. 3.

Diameter of azygos vein and left superior pulmonary vein.

Fig. 4.

Angle between left superior pulmonary vein and left brachiocephalic vein.

The left PAPVC spares the left pulmonary superior lobe from vascular congestion in left heart failure as the left upper pulmonary vein does not drain into the left atria [2]. However, in the case of right heart failure and hemodynamically significant ASD [9], pulmonary edema affects the left upper pulmonary lobe [2]. Patients with hemodynamically significant ASD may present atrial arrhythmias, complete heart block or pulmonary hypertension [9].

A longstanding effect of left PAPVC can result in enlargement of the cardiac silhouette because of right ventricular dilatation, pulmonary plethora, right hilum vascular prominence, and dilatation of central pulmonary arteries [2].

As previously highlighted in the literature, PAPVC has been associated with pulmonary hypertension [4]. In our case the HRCT shows that the pulmonary artery diameter is 31 mm, which is compatible with pulmonary hypertension, with a cut off of >29 mm [3] (Fig. 6).

Fig. 6.

Diameter of pulmonary artery.

In case of necessity, the definitive treatment of PAPVC consists in the surgical separation of the pulmonary venous system from the systemic circulation [1]. In our thorax HRCT scan without contrast media the heart size was not enlarged. Thus, if present, the ASD cannot be excluded. Patient's symptoms and pulmonary artery diameter could be related to his repeated bouts of smoking-related bronchitis, taking into account his medical history.

We consider our case worthy of attention due to the connection between the left upper pulmonary vein and the left thoracic internal vein which makes this case unique. Said connection had not been previously described in literature.

Conclusion

The angle between the left upper pulmonary vein and the brachiocephalic vein may affect the different size between the left upper pulmonary vein and the azygos vein. We cannot formally exclude an ASD as the thorax HRCT scan had been carried out without contrast media. It is the first case which describes the connection between the left upper pulmonary vein and the internal thoracic vein.