Congenital pulmonary venolobar syndrome: Value of multidetector computed tomography in preoperative assessment.

A 6-month old baby referred to our department because of recurrent attacks of respiratory distress with chest infection. Chest radiology revealed reduction of the right hemithorax with mediastinal shift to the right. Multidetector computed tomography showed hypoplasia of the right lung and right pulmonary artery, systemic arterial supply to the lung from the abdominal aorta, and and absence of right venous drainage to the left atrium. This picture is consistent with congenital pulmonary venolobar syndrome. The patient underwent right pneumonectomy; the postoperative course was uneventful.

Congenital pulmonary venolobar syndrome (CPVLS) refers to a wide spectrum of pulmonary developmental anomalies that involve abnormal connections of the pulmonary parenchyma, the pulmonary and systemic vasculature, and, rarely, the gastrointestinal tract. Any of the anomalies described in this syndrome may appear singly or in combination.

Case Report

We present a case of a 6-month-old baby who came to our attention because of repeated attacks of respiratory distress with chest infections. Chest radiograph showed reduction of the volume of the right lung with shift of the mediastinum to the right side. Chest computed tomogram (CT) confirmed the above mentioned data in addition to demonstration of abnormal vascularization of the right lung [Figure 1a]. Bronchoscopy showed bifurcation of the right main stem bronchus, a pattern similar to what is usually seen in the left tracheobronchial tree. The echocardiogram demonstrated dextrocardia, marked hypoplastic right pulmonary artery, but no intracardiac anomalies. Multidetector computed tomography (MDCT) of the chest demonstrated hypoplastic right lung and tiny right pulmonary artery [Figure 1b], abnormal systemic blood supply arising directly from the aorta below the diaphragm [Figure 1c], and an absence of right pulmonary venous drainage to the left atrium [Figure 1d]. Persistent left superior vena cava was also observed.

Figure 1

(a) Chest CT shows hypoplasia of the right lung, mediastinal shift and abnormal vascularization of the right lung; (b) MDCT chest showing small right pulmonary artery (white arrow); (c) MDCT chest showing systemic arterial supply of the right lung; (d) MDCT chest showing absence of right pulmonary venous drainage to left atrium

The patient underwent right pneumonectomy through a right posterolateral thoracotomy. At surgery, the lung was hypoplastic with only one incomplete oblique fissure. The right pulmonary artery was very small [Figure 2a], the main arterial supply was through multiple branches coming through the diaphragm and entering the lung through the diaphragmatic surface [Figure 2c]. The venous drainage was through a single large vein draining to the inferior vena cava [Figure 2b]. The postoperative course was uneventful. Eight months after surgery, the patient is doing well.

Figure 2

(a) Operative view showing very small right pulmonary artery; (b) showing the scimitar vein; (c) showing the resected right lung, black arrows points to the stumps of the systemic arteries entering the lung through the diaphragmatic surface

Discussion

This patient's findings are consistent with several features of a syndrome described by Felson as CPVLS. Major components of CPVLS include hypogenetic lung, partial anomalous pulmonary venous return, absence of a pulmonary artery, pulmonary sequestration, systemic arterialization of the lung, absence of the inferior vena cava, and accessory diaphragm. Minor components of CPVLS include tracheal trifurcation, eventration and partial absence of the diaphragm, phrenic cyst, horseshoe lung, esophageal and gastric lung, anomalous superior vena cava, and absence of the pericardium.[1] The primary feature of CPVLS is an abnormal drainage of a right pulmonary vein into the vena cava. This abnormal drainage course of the vein can often be seen on plain chest radiograph as a curvilinear density along the right heart border. Because this radiological sign resembles the Turkish sward, the anomaly was subsequently named the “scimitar syndrome.”[2]

Traditionally, angiography has been used for imaging of pulmonary vascular anomalies, especially when pulmonary sequestration or scimitar syndrome is suspected.[34] The objective is to identify the anomalous vessels (arteries and veins) in order to plan surgery and avoid accidental division or ligation. With advancement of CT technology, several studies have suggested the value of CT angiography as a noninvasive alternative in cases of pulmonary sequestration or CPVLS.[5-7] More recently, the introduction of MDCT allows improved delineation of the complex and variable anatomic abnormalities seen in patients with CPVLS obviating the use of angiography or magnetic resonance angiography for diagnosis.[8]

The clinical presentation of CPVLS is variable and depends mainly on the presence of associated cardiac anomalies and the potential development of pulmonary hypertension due to a large left to right shunt through the systemic arterial supply to the right lung. Some patients are symptomatic in the newborn period presenting with respiratory insufficiency and/or cardiac failure. Surgery is indicated for such patients and the success depends on the nature and severity of the underlying abnormalities.[9] This case underwent pneumonectomy. On the contrary, some surgeons may recommend coil embolization (or surgical ligation) of the systemic arterial supply and re-routing of the anomalous vein to the left atrium. The aim is to conserve lung tissue and avoid the long-term issues of pneumonectomy in a young infant. However, in this infant, the right pulmonary artery was very tiny supplying only part of the upper lobe, and the main blood supply was from the systemic artery. So, the consequences of embolization or ligation of the systemic artery was unpredictable.

Another group of patients presents during young adulthood with recurrent pulmonary infections. The infections usually affect the right lower lobe which is most likely to be the site of pulmonary sequestration. These patients may require lobectomy or occasionally right pneumonectomy to prevent recurrent infections.[10]

It is not uncommon to diagnose CPVLS as incidental finding in a chest radiograph. In such cases, due to absence of symptoms, these patients can be managed conservatively.

In summary, the term CPVLS is an umbrella to a group of pulmonary parenchymal and vascular anomalies that may present singly or in combination. The presence of any of these anomalies mandates search for the others. MDCT is an excellent diagnostic tool for delineation of the components of this syndrome.