Systemic Artery-to-Pulmonary Artery Fistula Mimics Pulmonary Embolus

Abstract

Systemic artery-to-pulmonary artery fistula (SA-PAF) is a rare phenomenon that can resemble a filling defect on computed tomography angiography (CTA). SA-PAF can be due to congenital or acquired etiologies and can alter the hemodynamics of the pulmonary circulation, with the most serious reported complication being hemoptysis, requiring embolization. We describe a case of an unusual SA-PAF between the right inferior phrenic artery and the right lower lobe pulmonary artery that mimicked an unprovoked pulmonary embolus (PE) on standard CTA in a patient with cardiomyopathy. This SA-PAF was interpreted on CTA as PE due to the presence of a filling defect, revealing that not all filling defects are PE. SA-PAF should always be considered when the clinical context or the imaging findings are atypical, specifically with an isolated filling defect visualized in the inferior lower lobe pulmonary artery. The false-positive PE was the result of mixing of systemic non-opacified blood with opacified pulmonary arterial blood.

Right inferior phrenic artery to right pulmonary artery fistula causing hemothorax: A case report

“…A unique aspect of our case is the presence of hemothorax associated with SA-PAF. A literature search for fistula-related hemothorax usually described arteriovenous fistulae in the pulmonary circulation and previous papers discussing SA-PAFs do not appear to mention hemothorax as a complication [ [6] , [7] , [8] ]. Given its presence and the significant reduction in chest tube fluid volume after embolization, it is reasonable to deduce that the SA-PAF was the source of bleeding into the pleural space.…”

Serial assessment of computed tomography angiography for pulmonary and systemic arteries using a reduced contrast agent dose for the diagnosis of systemic artery-to-pulmonary artery shunts

“…It is difficult to diagnose PE with CTA-S alone when contrast enhancement is not enough. Furthermore, the SPSs mimicked PE in CTA-P [ 16 ]. It has been reported that the combination of filling defects in the pulmonary arteries on CTA-P and enhancement of the pulmonary arteries on CTA-S suggests SPSs [ 15 , 20 ].…”

“…Although CTA is considered a less invasive screening method for SPSs, it is often difficult to diagnose SPSs confidently differentiating from pulmonary embolism (PE), enhancement unevenness and artifacts using CTA. PE is one of the causes of hemoptysis and is often accompanied by filling defects in the pulmonary arterial branches of CTA-P, mimicking SPSs [ 15 , 16 ]. In this case, it is important to identify the abnormal enhancement in CTA-S at the same part of the filling defects in the responsible pulmonary arterial branches in CTA-P, which is a characteristic of SPSs, to distinguish SPSs from PE.…”

Successful transcatheter arterial embolization of asymptomatic aneurysm associated with left inferior phrenic artery-to-left pulmonary artery fistula: A case report

“…We performed a search of the PubMed database using the following terms: “phrenic artery,” “pulmonary artery,” and “fistula.” Our search yielded nine articles. After excluding two articles that were not written in English and those that did not specifically relate to inferior phrenic artery-to-left pulmonary artery fistulas, we reviewed four articles discussing a total of five cases ( Table 1 ) [ 1 , 2 , 5 , 6 ].…”