Case Report

In July 2014, a 27-year-old woman with atypical chest pain and exertional dyspnea (New York Heart Association class III) was referred to our institution. Her clinical history included recurrent episodes of fever 4 months earlier. A grade 3/4 diastolic murmur was audible at the left parasternal border. Transthoracic echocardiograms showed an AVF arising from the right coronary sinus and extending through the interventricular septum into the LV (Fig. 1). Mild-to-moderate AV regurgitation was also found. Selective coronary angiography and aortography revealed no evidence of coronary abnormalities. The patient tested positive for human immunodeficiency virus (HIV) with a normal CD4 count. Test results for infection, such as leukocyte count, sedimentation rate, and C-reactive protein level, were normal on admission. The patient underwent closure of the AVF with the use of an autologous pericardial patch and transaortic resection of the ventricular tissue of the fistula (Fig. 2). For technical reasons, complete evaluation with histologic analysis of the fistula was not possible.

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A postoperative transesophageal echocardiogram showed no residual shunt and minimal AV regurgitation (Fig. 3). The patient was transferred to the intensive care unit, recovered uneventfully, and was discharged from the hospital on the 6th postoperative day. As of October 2018, she was asymptomatic.

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Discussion

Approximately 94% of AVFs caused by sinus of Valsalva aneurysm rupture originate from the right coronary sinus and involve primarily the right ventricle.⁷ However, AVF location may be less predictable when the defect is a complication of aortic dissection, infective endocarditis, or AV surgery. The main differential diagnosis is a congenital aortoventricular tunnel (AVT) connecting the ascending aorta and the ventricular cavity through an extracardiac channel. The aortic orifice in an AVT is usually in the ascending aorta above the sinotubular junction, whereas in an AVF, it is usually in the sinus of Valsalva and predominantly communicates with the LV.⁸ The involvement of the interventricular septum (Fig. 1A) in our patient was notable because similar echocardiographic findings can be found in aortic root or myocardial abscess. Although we could not exclude an infectious component because of the patient's HIV and recurrent fever 4 months earlier, we found no evidence intraoperatively of previous or active infection. Echocardiograms clearly revealed the origin of the lesion and its saccular extension into the basal septum (Fig. 1A). However, because the patient had reported atypical chest pain, preoperative cardiac angiography was necessary to rule out coronary abnormalities before repair.

When left untreated, AVF leads to heart failure over a variable time; thus, prompt repair is indicated when the diagnosis is made. Despite the availability of percutaneous techniques, especially for symptomatic and high-risk patients,⁴ surgical repair is the primary treatment. The timing of surgery is determined by the patient's clinical manifestations, the origin of the lesion, and the presence of associated disease. Surgical techniques for AVF and for AVT are similar, varying from direct suturing of the defect with or without a patch, to more complex procedures such as aortic root or AV replacement.⁹

In our patient, we attained good exposure of the ventricular side of the fistula by retracting the AV cusps, thus facilitating transaortic resection of the ventricular tissue. Subsequent defect closure was exclusively on the aortic side with use of an autologous pericardial patch. We were concerned that additional patch reinforcement from the ventricular side might compromise the morphology of the corresponding right coronary sinus and cusp and the function of the AV (Fig. 3).

In conclusion, AVF is a rare and insidious lesion with unpredictable anatomic and clinical patterns. Prompt intervention is crucial to avoid progression to congestive heart failure and AV dysfunction.