Microscopic Pulmonary Arteriovenous Malformations Diagnosed by Selective Microbubble Testing from the Pulmonary Artery: A Case Report

Abstract

Objective: We report a case of microscopic pulmonary arteriovenous malformations (PAVMs) diagnosed by selective microbubble testing from the pulmonary artery.

Case Presentations: A 56-year-old woman simultaneously experienced multiple cerebral infarctions, acute right pulmonary artery thromboembolism, and deep vein thrombosis at 44 years old. Conventional, non-selective microbubble testing using transesophageal echocardiography (TEE) was positive. She began warfarin administration, which was discontinued after 6 months due to no thrombosis recurrence and no congenital thrombosis predisposition. Later, preoperative TEE did not confirm patency of the foramen ovale, but non-selective microbubble testing was again positive. Although a clear patent foramen ovale (PFO) could not be identified, the possibility of a PFO with an extremely small shunt tract could not be ruled out and required further examination. Attempts to pass the foramen ovale with a multipurpose catheter under TEE guidance were unsuccessful. Next, we inserted a catheter into the pulmonary artery for selective microbubble testing. We observed bubble inflow from the right pulmonary artery to the right upper pulmonary vein, which enabled a diagnosis of microscopic PAVMs. Although these might constitute a contributing factor to paradoxical embolism, the shunt volume was thought to be small. We opted against shunt embolization, instead prescribing edoxaban to prevent thrombosis.

Conclusion: Selective microbubble testing from the pulmonary artery could detect microscopic PAVMs and was effective for differentiation from a PFO.