Intrahepatic Portosystemic Shunt In Cardiac Amyloidosis: Turning Off The Faucet Leads To Resolution Of Hepatic Encephalopathy And Improvement In Heart Failure Symptoms

Abstract

<h3>Introduction</h3> Spontaneous portosystemic shunts (SPSS) are extremely rare and usually extrahepatic due to portal hypertension in the setting of cirrhosis. Current knowledge regarding SPSS in adults in the absence of cirrhosis is limited. The implications of SPSS in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) are unknown. <h3>Case</h3> A 76-year-old man with a history of HTN, CAD and systolic dysfunction (EF 45%) presented to the hospital with symptoms of HF exacerbation and cognitive dysfunction. Initial cardiac labs were notable for a borderline elevated troponin and high natriuretic peptic level. Hepatic labs were notable for mild elevation in transaminases, thrombocytopenia and an elevated ammonia level. Transthoracic echocardiogram (TTE) revealed that the EF was stable at 45%, but there was biatrial enlargement and progression of concentric LVH to 1.8cm and resultant small LV cavity (EDV index 39ml/m²), suspicious for infiltrative cardiomyopathy (Fig A). SPEP/UPEP with immunofixation and serum free light chains were normal and Tc-99m PYP study was consistent with ATTR-CM (Fig B). Abdominal US revealed a large intrahepatic venous shunt from the right portal vein to the right hepatic vein. Right heart catheterization, portal venogram and liver biopsy revealed a right atrial pressure of 14mmHg, cardiac output of 6.2L/min, normal pulmonary vascular resistance, hepatic vein pressure of 14mmHg, portal vein pressure of 15mmHg, confirmation of the large SPSS (Fig C) and no evidence of cirrhosis. The patient underwent embolization of the SPSS with a 22mm vascular plug (Fig D). Following closure, the patient's HF symptoms and HE improved dramatically and his abnormal hepatic labs normalized. He was started on a stabilizer for the treatment of his ATTR-CM. At one year, he has not had recurrent symptoms of HE, nor repeat hospitalization for HF exacerbation. <h3>Discussion</h3> This patient most likely had a SPSS that only manifested clinically in the setting of elevated right atrial and hepatic pressures due to the development of ATTR-CM. Ultimately, the decision was made to close the SPSS for two reasons. The first was to treat HE—in the same way that transjugular intrahepatic portosystemic shunt (TIPS) procedure can cause HE and subsequent TIPS closure can be an effective treatment for refractory HE. The second was to improve HF symptoms. Although this patient's cardiac output was "normal", it was likely actually high in the context of the severe LVH and small LV cavity due to ATTR-CM and the increased venous return was poorly tolerated given the underlying restrictive cardiomyopathy.