Abernethy – An unusual suspect

December 13, 2018 0 By FM

An eight-year-old boy was presented to his paediatrician with breathlessness. Upon regular examination, the pediatrician identified a murmur and referred the child to Dr. Shine Kumar, Paediatric Cardiologist at Amrita Institute of Medical Sciences, Kochi, for further evaluation. The child underwent ECG, X-ray, and echo. ECG and X-ray were nonconclusive. However, echo identified high pressure in the lung arteries, indicative of pulmonary hypertension.
Pulmonary hypertension is a type of elevated blood pressure, but one that involves the arteries of the lung and the right side of the heart. Symptoms include breathlessness, fatigue, dizziness, as well as fast heart beats. There are several causes of pulmonary hypertension like congenital heart conditions, left-sided heart disease, lung disease, blood clots in the lungs, other conditions such as blood disorders or tumours pressing against pulmonary arteries etc. Treatment is dependent on the cause of pulmonary hypertension and majority of the time, it is not curable, and only supportive treatment is available. Doctors can at best help manage the condition; often having to change and improvise on the medication or treatment options.
For an effective treatment, it was important to accurately diagnose the cause of pulmonary hypertension in this patient. Dr. Kumar’s team therefore carried out further investigative testing that included an abdominal ultrasound. The abdominal ultrasound identified an Abernethy malformation in the liver. Abernethy malformation is a congenital condition in which there is abnormal communication between the portal vein and the inferior vena cava, which causes elevated lung pressures. These are very rare vascular anomalies of the venous system of the abdominal region. Normally, de-oxygenated blood from the abdominal organs is drained by the portal vein into the liver and then circulated to the heart via the inferior vena cava. However, in case of Abernathy malformation, the liver is bypassed due to an extrahepatic portosystemic shunt and the blood is diverted directly to the systemic circulation via the inferior vena cava to reach the heart. These malformations are remnants of embryonic vessels and are typically congenital. There are two types of Abernathy malformations. Type I is predominantly found in females in whom there is a congenital absence of blood flow from the portal vein to the liver. Type II patients have an end-to-end shunt or an extrahepatic communication that allows for a complete diversion of the portal blood into the systemic veins. Type II on the other hand is predominant in males where the portal vein is hypoplastic and the blood gets partially diverted from the portal vein to the inferior vena cava via a side-to-side shunt or extrahepatic communication.
Abernathy malformations are rare, occurring in less than 1% of the general population. They are generally detected incidentally in the paediatric population, during an investigation of associated liver or cardiac anomalies. It is much more challenging to identify in older patients especially in those with other chronic liver diseases and with no early diagnosis of congenital portosystemic shunts. Once identified, treatment is dependent on the type of malformation. Type I malformations typically require a liver transplantation, whereas type II malformations are completely curable in a simpler manner with either surgical ligation or endovascular occlusion.
Within 2 weeks of diagnosing a type II Abernathy malformation, the 8-year-old boy underwent a keyhole surgery through a vein in the leg, and the abnormal extrahepatic channel was occluded using a metallic plug. Regular follow ups showed that the treatment was successful, and the child did not have pulmonary hypertension. It has been 2 years since the procedure and the patient is doing well.
“Pulmonary hypertension can be caused due to many conditions, most of them are not curable. The ultrasound identified a type II Abernathy malformation in our patient, which was a very fortunate diagnosis as it is one of the few treatable conditions that causes pulmonary hypertension,” says Dr. Kumar.