Figura 1. 3D color TEE. Right aorto-atrial fistula.

Figura 2. 3D color TEE. MemoPart device, designed for closure of 14-mm tubular ducts, closing the ri...

Figura 3. Angiography of the aortic root. The arrow shows the deployed MemoPart ASD device closing t...

Figura 4. Angiography. The star shows the extraction of the embolized first device through the femor...

Introduction

Aorto-atrial fistulae are a rare condition characterized by an abnormal connection between the aorta and the atria1. Their prevalence and incidence in the population are unknown. They typically occur secondary to infective endocarditis, non-coronary sinus of Valsava rupture due to aneurysmal defect, periprosthetic abscesses, cardiac surgeries such as aortic valve replacement, or congenital heart disease plus other anomalies like bicuspid aortic valve. There are few documented cases where it has been reported as a complication of aortic dissection2. The diagnostic method of choice is echocardiography, and treatment can be surgical or endovascular depending on fistula location and association with other structural heart defects3.

Case description

The patient is a 47-year-old man with cardiovascular risk factors: morbid obesity, hypertension, former smoker,sedentary lifestyle, and a history of congenital solitary kidney, under follow-up by the Department of Cardiology due to a 6-month history of lower limb edema, ascites, and progressive dyspnea up to functional class III. Echocardiography + Doppler revealed a 65% ejection fraction, left ventricular hypertrophy, grade III diastolic dysfunction, dilated right ventricle, biatrial enlargement, right coronary sinus aneurysm with shunt to the right atrium, thoracic aorta dilation (63 mm), diastolic reverse flow 44 cm/s, moderate tricuspid valve regurgitation, pulmonary hypertension (systolic pulmonary artery pressure 73 mmHg), and pulmonary trunk diameter 39 mm. A transesophageal echocardiography (TEE) confirmed fistula over the right coronary sinus towards the right atrium with a proximal mouth of 7 mm and a distal mouth of 8 mm, with continuous flow and QP/QS of 1.8, gradient 24 mmHg, and intact interatrial and interventricular septum (Figure 1).

An aortocoronary angiography revealed a fistula at the coronary sinus level towards the right atrial cavity with QP/QS 3.0 and pulmonary hypertension by right catheterization with a mean pulmonary artery pressure of 40 mmHg.

The patient was scheduled to undergo a right aorto-atrial fistula closure with intraprocedural TEE control. The right femoral artery and vein were punctured with a JR catheter. The lesion was crossed over from the aorta to the right atrium with a 0.035” hydrophilic-coated Glidewire (Terumo Medical Corporation, Japan) exchange guidewire. The guidewire was threaded through the superior vena cava and exited through the femoral vein, thus establishing an arteriovenous loop. Through the vein, a 9-French sheath was advanced up to the ascending aorta. Then, the dilator and guidewire were removed. A MemoPart (Lepu Medical, China) device, designed for closure of 14-mm tubular ducts, was then inserted. On the aortic side, the 18-mm retention disc opened, and the remainder of the device was deployed over the lesion in a good position under echocardiographic control (Figure 2). There was minimal residual intradevice flow, and the device was released without issues.

The patient was transferred to the Coronary Care Unit, where he stayed for 4 days for optimal heart failure treatment. His clinical condition improved, and the echocardiographic control showed the device in normal position.

Ten days after the procedure, the patient developed severe signs of right heart failure. A fluoroscopy revealed device embolization towards the left pulmonary artery. The patient was admitted to the Coronary Care Unit with signs, symptoms, and laboratory findings consistent with multiorgan failure, requiring intravenous inotropic and chronotropic therapy. In order to stabilize him and extract the embolized device, two days later the fistula was closed in the cath lab. The procedure consisted in the same maneuvers as in the previous procedure to establish an arteriovenous loop. The right aorto-atrial fistula was closed with a 9-mm MemoPart ASD (Lepu Medical, China) device specially designed for atrial septal defect closure. This device has a 23-mm left-side disc (which is larger than the 18-mm retention disc of the previously used device). Device deployment at the site of the fistula resulted in the 21-mm right disc going into the right atrium, as visualized on the control 3D transesophageal echocardiography (Figure 3). The device was in good position and deployed without issues, leaving a small 1-mm residual flow. After this procedure, the embolized device was extracted using the retention disc hub. Due to its position, it was partially sheathed and removed together with the sheath through the femoral vein without complications (Figure 4).

The patient continued inotropic support for 5 days with negative fluid balance, showing clinical improvement, and normalization of laboratory parameters. A Doppler echocardiogram showed no residual shunt. Discharge from the hospital was on the seventh day after the procedure.

Discussion

Fistulae located between the aorta and the atria are rare; they are often the result of an underlying condition affecting cardiac structures. They can be congenital; secondary to conditions such as aortic dissection, infective endocarditis, or valve replacement; or iatrogenic. Secondary causes lead to local deterioration of the cardiac wall, resulting in fistulous connections, while iatrogenic causes are more traumatic in nature. Signs and symptoms include volume overload and heart failure, and patients often present with fever, continuous murmurs, dilated cardiomyopathy, and lower limb edema1.

Early detection and diagnosis of this serious pathology depend on its echocardiographic identification. Combining 3D imaging techniques, such as transesophageal echocardiography or computed tomography, is highly recommended whenever possible, as it provides spatial orientation and high anatomical definition for procedure planning purposes. The assessment may also include cardiac magnetic resonance imaging or cardiac catheterization to further quantify the shunt4.

Due to the low incidence of fistulae between the aorta and the atria, treatment strategies depend on the underlying disease, and interventions are based on expert opinions and consensus among treating physicians. However, fistula closure is recommended in symptomatic patients5.

Available evidence on this matter is scarce and based solely on clinical cases or case series. More information is needed to better define optimal therapeutic strategies in this scenario6.

Conclusion

Aorto-atrial fistulae are rare and uncommon, but they can lead to serious complications such as refractory heart failure, sometimes requiring their closure for clinical improvement. Given the limited evidence available on the treatment of these pathologies, managing these patients is a challenge for medical personnel.

Interventional procedures are effective and much less invasive than surgery, allowing for rapid recovery of clinically compromised patients. The possibility of complications such as device embolization highlights the importance of operator expertise and appropriate materials for treatment.

Due to the patient’s progression, choosing a double-disc device seems like a better alternative for fistula resolution, even though the initial goal with the first chosen alternative was to leave a smaller disc on the aortic side.

1. Fierro EA, Sikachi RR, Agrawal A, Verma I, Orjrzanowski M, Sahni S. Aorto-Atrial fistulas: A contemporary Review. Cardol Rev. 2018; 26(3): p. 137-144.

2. Hsu RB, Chien CY, Wang SS, Chu SH. Aorto-right atrial fistula a rare complication od aortic dissection. Tex Heart Inst J. 2000; 27(1): p. 64-66.

3. Castano O, Bastidas O, Ocampo Chaparro JM, Urrea Zapata JK, Bucheli V. Fístula Aorto-atrial derecha: unapresentacióninusual. RevistaColombiana de Cardiología. 2018; 25(4): p. 280.

4. Tamargo M, Elizaga J, Fernandez Aviles F. Cierre percutáneo de unafístula entre la aorta y la aurículaizquierda. REC Interv. Cardiol. 2023; 5(3): p. 222 -224.

5. Jainandunsing JS, Linnemann R, Maessen J, et al. Aorto-atrial fistula formation and therapy. J Thorac Dis. 2019; 11(3): p. 1016 - 1021.

6. Foster TJ, Amin AH, Busu T, et al. Aorto-cardiac fistula etiology, presentation, and management: A systematic review. Heart Lung. 2020; 49(3): p. 317 - 323.

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