Pulmonary Arteriovenous Malformation in Patients with Total Cavopulmonary Shunt: What Role Does Lack of Hepatic Venous Blood Flow to the Lungs Play?

Abstract

We examined the etiology of a long-term postoperative complication, pulmonary arteriovenous malformation (PAVM), in a patient who underwent total cavopulmonary shunt (TCPS). The patient underwent TCPS at the age of 3 years and 1 month, and a PAVM developed. At the age of 10 years, TCPS was switched to total cavopulmonary connection to facilitate circulation of hepatic venous blood to the pulmonary artery. As a result, oxygen saturation increased. These findings suggest that the absence of pulmonary circulation of hepatic venous blood is involved in the development of PAVM.

Pulmonary hepatic flow distribution in total cavopulmonary connections: Extracardiac versus intracardiac

“…The prognosis for Fontan patients with PAVMs is often poor without re-operation to reconstruct the Fontan baffle. PAVMs have been postulated in the past to be secondary to disproportionate distribution of hepatic factors between the two lungs1–5. More recent studies confirmed that geometric configuration of the total cavopulmonary connection (TCPC) that preferentially stream hepatic vein (HV) flow to a single lung leads to PAVMs6.…”

Flow simulations in arbitrarily complex cardiovascular anatomies – An unstructured Cartesian grid approach

“…These malformations are normally prevented by humoral factors released by the liver [36][37][38][39] and carried to the lungs by the IVC. Their presence in the left lung would thus imply that most of the IVC flow is directed to the RPA, while the preferential orientation of the IVC towards the LPA leads one to the opposite conclusion.…”

Imaging and patient-specific simulations for the Fontan surgery: Current methodologies and clinical applications

“…Another major complication that results in Fontan failure and depends on the TCPC design is progressive hypoxia due to the development of unilateral PAVMS (Moore, Kirby et al 1989; Pandurangi, Shah et al 1999; Shinohara and Yokoyama 2001; Duncan and Desai 2003; Brown, Ruzmetov et al 2005). PAVMs are intrapulmonary shunts, connecting the pulmonary arteries directly to the pulmonary veins, thus allowing the de-oxygenated blood from the systemic circulation to return to the left atrium without flowing through the gas exchange units.…”

“…Furthermore, the intrapulmonary shunts lead to a drop in pulmonary vascular resistance, which tends to direct more flow to the diseased lung creating a positive feedback loop of increasing hypoxia. Although the underlying mechanism leading to PAVMs is unknown, studies have shown that liver derived factors present in the hepatic venous blood prevent their formation (Pandurangi, Shah et al 1999; Justino, Benson et al 2001; Shinohara and Yokoyama 2001; Duncan and Desai 2003; Pike, Vricella et al 2004). While it is not known what concentration of this hepatic factor is required for normal lung development, it is clear that an unbalanced hepatic flow distribution to the left and right lungs due to an inadequate design of the IVC-to-PA conduit during the 3 rd stage of the TCPC surgery puts patients at risk for PAVMs.…”