Trans-catheter closure of an unusual type of Abernethy malformation in a child presenting with severe pulmonary hypertension

Abstract

Abernethy malformation is a congenital extra-hepatic porto-systemic shunt. This malformation is characterized by an abnormal connection between the portal vein or its branches and one of the systemic veins. Though rare, this anomaly can lead to pulmonary hypertension. Drainage of Abernethy malformation into coronary sinus is extremely rare. We describe a child with Abernethy malformation with unusual drainage into coronary sinus. The abnormal channel was successfully closed by trans-catheter technique with normalisation of pulmonary arterial pressures.

Introduction

Abernethy malformation is characterised by an abnormal connection between the portal vein or its branches and one of the systemic and can lead to different hepatic and systemic complications. It can also lead to severe pulmonary hypertension. So its identification as a possible cause of pulmonary hypertension is very important. ¹ Its drainage into coronary sinus is extremely rare. We describe a child who presented with severe pulmonary hypertension. During further workup, she was detected to have an unusual type of Abernethy malformation and subsequently underwent successful transcatheter device closure of the malformation. Pulmonary artery pressures normalised after successful closure of the malformation.

Case report

A 5-year-old girl child was diagnosed with severe pulmonary hypertension. She had hyperkinetic precordium, hepatomegaly, and a prominent second heart sound. Her echocardiogram revealed severe pulmonary hypertension with mild right ventricular dysfunction. Pulmonary artery systolic pressure was 72 mmHg. Coronary sinus was unusually dilated (Fig 1a and b). CT of the chest was performed for further evaluation which showed anomalous drainage of the portal vein into the coronary sinus through a large left-sided venous channel, and the main portal vein to the liver was hypoplastic (type 2 Abernethy malformation, as shown in Fig 2a and b). Pulmonary veins were draining into left atrium without obstruction. She was stabilised with intravenous diuretics, Milrinone, oral Sildenafil, and endothelin receptor antagonist Macitentan. Diagnostic cardiac catheterisation was performed. She had mildly elevated right atrial pressures. Pulmonary arterial pressure was 36/17/26 mmHg. Portal venogram was performed, which showed a large left-sided venous channel draining the majority of the portal venous blood into dilated coronary sinus. Main portal vein was significantly hypoplastic and it was draining into liver (Fig 3a and video 1). Balloon occlusion test was performed. Anomalous vein was occluded with 10 × 20 mm Mustang balloon. Baseline portal venous pressure was 12 mmHg which increased to 18 mmHg after 10 minutes of balloon occlusion. The balloon occlusion angiogram showed better filling of the main portal vein and portal radicles (Fig 3b and video 2). Device closure of the venous channel was performed using a 14 mm LIFETECH™ vascular plug (Fig 3c). A repeat angiogram was performed, which showed complete closure of the anomalous venous connection. The portal venous radicles were seen filling into liver parenchyma. To prevent portal vein thrombosis, she was discharged on oral anticoagulant (Warfarin) and antiplatelet agent along with dual pulmonary vasodilators. Her ultrasound abdomen on follow up showed normal-sized portal vein measuring 5.7 mm with normal flow. Her pulmonary artery pressure and right ventricular function normalised at 6-month follow up.

Figure 1. (a) Transthoracic apical 4 chamber view showing dilated right atrium (RA) right ventricle (RV) and coronary sinus (red arrow). (b) Continuous wave Doppler showing peak tricuspid regurgitation gradient of 62 mmHg.

Figure 2. (a) 3D rendition of CT images in sagittal view to profile the drainage of left sided venous channel into dilated coronary sinus. (b) 3D rendition of CT images showing hypo plastic main portal vein with large left sided venous channel draining majority of the portal venous return into dilated coronary sinus.

Figure 3. (a) Portal venogram showing hypo plastic portal vein to liver and large Abernethy vein draining into coronary sinus. (b) Balloon occlusion test showing improved filling of portal vein and portal radicles after complete occlusion of the anomalous vein. (c) Fluoroscopic image showing device position after porto systemic shunt closure.

Discussion

Abernethy malformation is a type of congenital porto-systemic shunts. Persistence of this shunt in postnatal life can lead to hepatic and systemic complications including severe pulmonary hypertension. Its identification as a possible cause of pulmonary hypertension is very important. ^1,2,5 During normal fetal development, there are right and left umbilical veins, which are connections between the placenta and fetal heart. Hepatic sinusoids develop between the two, leading to regression of the right and cranial portions of the left umbilical vein, thus interrupting the connections between the fetal heart and placenta. Portal vein develops from the right caudal vitelline vein and the left caudal umbilical vein. Persistence of the cranial portion of the left umbilical veins may lead to an abnormal connection between the portal vein and the coronary sinus. It is further classified into two types, depending on the anatomy. Type 2 Abernethy malformations have side-to-side connections between the portal and systemic circulation. Blood flow to the liver is through hypoplastic portal vein. The drainage site of the anomalous channel varies. Its drainage into coronary sinus is very rare. The first case of Abernethy malformation draining into the coronary sinus was described by Loomba et al ¹ and very few cases are reported in the literature. ^1–3

Other complications of congenital port-systemic shunt are neonatal cholestasis and galactosemia early in life, hepatic encephalopathy, hepatopulmonary syndrome, portopulmonary hypertension, and hepatic tumours in few cases, which are mostly reversible if diagnosed and treated early. ⁴ The management includes percutaneous or surgical shunt closure or liver transplantation if not amenable to shunt closure. Pulmonary hypertension has been reported in 13–66% of these patients and carries a grave prognosis if detected later in the disease course. ⁴ However, Bobhate et al, found good reversibility of pulmonary hypertension in these patients, as four out of six patients had normal pulmonary arterial pressures and pulmonary vascular resistance confirmed by cardiac catheterisation done 1 year after the shunt closure. They concluded that congenital port-systemic shunt can be one of the potentially treatable causes of pulmonary hypertension if the shunt is closed earlier. ⁵ Similar results were noted in a multicentric study done by Nageswara et al, in which seven of the eight patients could be completely weaned off the pulmonary vasodilators on follow up. ² Our child had a short history. Closure of the malformation resulted in normalisation of pulmonary arterial pressures. These patients need to be maintained on oral anticoagulants to prevent portal venous thrombosis. Follow up ultrasonography of liver is essential to see the portal venous flow to the liver.

Conclusion

Congenital porto-systemic shunts can have a varied presentation, not only limited to hepatic features but also extra-hepatic manifestations. They can present at any age, from neonatal to adulthood. Pulmonary hypertension can be one of the major complications for these patients. Active search for the causes of secondary pulmonary hypertension can lead to normalisation of pulmonary arterial pressure if corrected earlier.