Aorto-Right Atrium Fistula—A Surgical Resolution

Aorto-atrial fistulas are rare anatomical anomalies that can arise from various etiologies, with endocardial infections being the most common cause in adults. Their true impact on the population is unknown. Mostly, they correspond to a fistula that communicates the aorta with the right atrium, and secondarily with the left atrium, with an incidence of 2 in 1. 

Their presentation can vary from asymptomatic forms to forms of heart failure with pulmonary hypertension, with the most common symptoms being dyspnea, excessive fatigue, and palpitations. 

The diagnosis is mainly made by transthoracic or transesophageal echocardiography, which should be complemented with a CT scan for anatomical guidance in planning for surgical or endovascular resolution. 

Small and asymptomatic fistulas can be treated conservatively with strict follow-up, while larger fistulas—symptomatic or those that generate hemodynamic impact—require immediate closure by surgical or endovascular approaches. 

Clinical Case 

This clinical case involves a 24-year-old patient with no relevant medical history, who was referred to the center with a diagnosis of right-sided endocarditis after two months of medical treatment and follow-up at another institution.  

Upon arrival, the patient was in a hemodynamically stable condition with persistent fever. New laboratory tests, cultures, tomography, and echocardiograms were performed.  

The transthoracic and transesophageal echocardiogram showed good left ventricular function (LVEF 75 percent) and right ventricular function (TAPSE 29 mm), moderately dilated right cavities, an aneurysm of the noncoronary sinus with rupture toward the right atrium, severe left-to-right shunt, tricuspid annulus dilatation, and small vegetation with adequate coaptation, with the rest of the valve pairs being normal. Estimated PSAP was 50 mmHg due to hyperflow. Laboratory tests showed leukocytosis and anemia.  

With a diagnosis of a fistulized coronary sinus aneurysm toward the right atrium associated with infectious endocarditis, emergency surgical resolution was indicated. Through conventional surgery with median sternotomy, extracorporeal circulation, aortic clamping, and cardiac arrest, repair with a bovine pericardial patch of the defect was performed on both the atrial and aortic sides, along with resection of vegetations adhered to the septal valve of the tricuspid valve associated with partial resection and plication of the same. The patient had an uncomplicated postoperative course, remained in the ICU for the first 48 hours postoperatively, and underwent prolonged hospitalization for intravenous antibiotic treatment with good evolution. 

Conclusion 

Aorto-atrial fistulas are rare with a wide spectrum of presentation. Due to their potential risks, anatomical understanding and prompt resolution are necessary. 

References

1. Jainandunsing JS, Linnemann R, Bouma W, Natour N, Bidar E, Lorusso R, Gelsomino S, Johnson DM, Natour E. Aorto-atrial fistula formation and closure: a systematic review. J Thorac Dis 2019;11(3):1031-1046. doi: 10.21037/jtd.2019.01.77
2. Elwatidy AF, Galal AN, Rhydderch D, et al. Aorto-right atrial fistula. Ann Thorac Surg 2003;76:929-31.
3. Gunarathne A, Hunt J, Gershlick A. Aorto-right atrial and right ventricular fistulae: a very rare complication of native bicuspid aortic valve endocarditis. Heart 2013;99:1708
4. Patel V, Fountain A, Guglin M, et al. Three-dimensional transthoracic echocardiography in identification of aortoright atrial fistula and aorto-right ventricular fistulas. Echocardiography 2010;27:E105-8

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