Successful treatment of abdominal aorto-right atrial fistula by vascular plug: A previously unreported cardiac malformation.

Introduction

Aorto-cardiac fistulas are defined as a sizable communication between the aorta and cardiac spaces, including the right atrium (RA), right ventricle, left atrium, or left ventricle. Aorto-atrial fistula is a rare condition mostly observed as an acquired or extremely rare congenital condition. Causes of the acquired condition are mainly complications of previous cardiac surgery, aortic root abscess due to bacterial endocarditis, paravalvular abscess, ruptured sinus of Valsalva aneurysm, or aortic dissection (1). Congenital cases have poorly defined characteristics with uncertain pathogenesis. Classic signs (continuous murmur) are mostly absent in congenital cases (2).

Here we report a case of congenital aorto-right atrial fistula (ARF) with a longer fistula tract. Surgical management is the mostly commonly used treatment option in these cases. In two previously reported cases of ARF originating from the ascending aorta, Amplatzer duct occluder (ADO) I and ADO II were used (3, 4). Our literature review suggested that only two reports on cases of a fistula to the RA originating from the descending thoracic aorta have been published. Surgical and Amplatzer vascular plug II were applied in these cases (5, 6).

Here we describe, for the first time, a descending abdominal aorta to the right atrial fistula, which was successfully closed by trans-catheter embolization using an Amplatzer vascular plug IV.

Case Report

A 2-year-old asymptomatic boy was referred to our clinic because of a continuous murmur that was more evident at the left upper sternal border. No other pathological finding was detected in his physical and chest X-ray examinations. During echocardiographic examination, a small shunt from the proximal descending aorta to the main pulmonary artery was observed and diagnosed as patent ductus arteriosus (PDA). We noted an abnormal, continuous, high-velocity flow into the RA, which was dilated, with a gradient of 75 mm Hg. The left and right ventricles were slightly dilated without any functional loss. An extra-cardiac structure was found to be open to the RA on the posterior lateral side of the inferior vena cave (Fig. 1). Computed tomography (CT) angiography confirmed a tortuous, large, and very long fistula (Fig. 2). No connection was observed between this fistula and the liver or the portal system on both CT and abdominal ultrasonography. This ruled out the possibility of hepatic arteriovenous fistula and hepatoportal fistula. Right and left heart catheterization was performed, which revealed a Qp/Qs ratio of 1.8: 1. Descending aorta angiography confirmed the diagnosis of a very small PDA and unusual tortuous fistula between the descending abdominal aorta and the RA (Fig. 3). A catheter was advanced to the fistula orifice directly from the abdominal aorta. The fistula was selectively engaged using a 5-Fr right Judkins catheter. A hydrophilic guidewire was then passed through the proximal fistula into the narrowing proximal portion of the fistula. This area measured approximately 5 mm. A 7-mm Amplatzer vascular plug IV device was loaded into the catheter, and the distal skirt of the device was placed on the narrow and curved part, 5-6 mm away from the proximal fistula. After device replacement, significant residual flow was observed, and thereafter, a second 8-mm Amplatzer vascular plug IV device was advanced close the residual leak (Fig. 4a). A non-selective contrast agent was injected into the abdominal aorta, which revealed occlusion of the fistulous tract with the Amplatzer vascular plug IV device in stable position at the proximal mouth of the fistula (Fig. 4b). PDA could not be closed as it could not pass through the catheter. No procedure-related complication occurred. The patient was discharged from the hospital on the second day with acetylsalicylic acid (5 mg/kg/day), and he remained well during the 6 months of follow-up.

Figure 1

Transthoracic echocardiogram, subcostal inferior vena cava view showing the aorto-right atrial fistula. ARF-aorto-right atrial fistula, IVC-inferior vena cava, RA-right atrium

Figure 2

Computed tomography angiography showing a tortuous, large, and very long fistula between the abdominal aorta and right atrium

Figure 3

Anterior–posterior angiograms of the abdominal aorta showing a tortuous fistulous tract between the abdominal aorta and right atrium (arrow)

Figure 4

(a) Devices were deployed to the narrow and curved part at a distance of approximately 5-6 mm from the proximal fistula; (b) no residual shunt was observed after detachment. Arrow indicates the position of the Amplatzer vascular plug IV

Discussion

ARF is an uncommon condition with unclear pathogenesis. Possible embryological abnormalities in the sixth aortic arch (arterial component) or sinus venous or cardinal veins (venous component) were accused for the fistula formation (6). Mostly, it was thought that congenital deficiency of the elastic lamina in the aortic wall (cystic medial necrosis) leads to this type of fistula (7). Most ARFs occur due to complications of surgical procedures, bacterial endocarditis, paravalvular abscess, ruptured sinus of Valsalva, and aortic dissection, and few of them are congenital (8, 9).

Our patient had no history of any surgical procedure to suggest an acquired origin. Presentation may be asymptomatic but once detected, closure is recommended to prevent potential complications. If complications, such as congestive cardiac failure, bacterial endocarditis, aneurysm formation, or spontaneous rupture, occur, they can be fatal.

Conclusion

Various occlusion devices and techniques are available for treating ARF. The percutaneous closure of ARF with an Amplatzer vascular plug type device IV can be considered as a therapeutic option in cases with favorable anatomy.