An Unusual Case of Aortic-Right Atrium Fistula: A Diagnostic and Therapeutic Challenge.

An aorta-to-right atrium (RA) fistula is an anomalous communication between the ascending or descending thoracic aorta and the RA. In this report, we describe a case of an idiopathic aortic root-to-RA fistula occasionally found during a coronary angiography performed in a young patient admitted for acute chest pain with evidence of multivessel coronary artery disease. The anatomical peculiarity of this fistulous communication is that it gave origin to collateral vessels furnishing the inferolateral wall of the left ventricle. The case represented a diagnostic and therapeutic challenge that required a multimodality imaging and a multidisciplinary team approach.

INTRODUCTION

An arteriovenous (AV) fistula is an abnormal communication between an artery and a vein, which results in shunting of blood from the high-resistance arterial circuit to the low-resistance venous circuits. Aortic root-to-right atrium (RA) fistulae are rare, especially in the absence of an aneurysm of the sinus of Valsalva.[1] We present the case of a young patient who was accidentally diagnosed with an AV fistula between aortic root and RA, during a coronary angiography performed for acute coronary syndrome. Unexpectedly from this anomalous communication arouses collateral branches furnishing the inferolateral wall of the left ventricle (LV). In the diagnostic phase, a multimodality imaging approach is crucial, while due to the complexity of coronary circulation, a multidisciplinary cardiovascular team is necessary for a patient-tailored therapeutic management.

CASE REPORT

A 48-year-old male with borderline hypertension, familial hypercholesterolemia, and no history of cardiovascular disease was admitted to our intensive care unit for chest pain at rest and dynamic alterations of the electrocardiogram in left precordial leads (ST-segment depression during symptoms); laboratory tests showed mild increase of high-sensitivity troponin I levels (3.84 ng/ml n.v. 0.01-0.05 ng/ml). Transthoracic echocardiography showed a moderate, concentric left ventricular hypertrophy, hypokinesis of the mid-basal segments of inferolateral wall, with normal global ejection fraction (55%); no relevant valvular heart disease nor pericardial effusion was evident [Figure 1a–f].

Figure 1

Transthoracic echocardiography, apical 4 chamber view (a), 2 chamber view (b) and 3 chamber view (c), short-axis view at the level of aortic valve (d), short-axis view at the level of aortic valve with color Doppler (e) and short-axis view at the level of ascending aorta (f). Normal chamber dimensions and regular wall thickness can be observed

The patient underwent coronary angiography from the right radial access, which documented a critical lesion of left main (LM) at bifurcation, a critical lesion of mid-distal left anterior descending artery (LAD), and occlusion of distal apical recurrent LAD [Figure 2a]. A thrombotic subocclusion of a first proximal obtuse marginal (OM) vessel was identified as the culprit lesion [Figure 2b]. Right coronary artery (RCA) appeared hypoplastic and was occluded at the proximal segment [Figure 2c]. An anomalous flow, originating from the aorta just underneath the origin of RCA, was detected.

Figure 2

Urgent angiography that demonstrated critical lesion of mid-distal anterior descending artery, occlusion of distal apical recurrent anterior descending artery, and thrombotic subocclusion of a first proximal obtuse marginal, as culprit lesion (a and b); occlusion of the right coronary artery at the proximal segment (c). Angiographic result after percutaneous coronary intervention of culprit lesion (d)

At selective injection, it appeared to be a huge fistulous communication between right Valsalva coronary sinus and the RA. Unexpectedly from this fistulous communication emerged several collateral vessels, oriented toward posterolateral wall of the LV [Figure 3a and b].

Figure 3

Coronary angiography (a and b), at selective injection, showing a huge fistulous communication between right Valsalva coronary sinus and the right atrium, with several collateral vessels emerging from the fistula and oriented toward posterolateral wall of the left ventricle. Angio-computed tomography (c and d) showing the fistolouse comunication between ascending aorta and right atrium

At this point, due to the ongoing symptoms of ischemia and instability of the patient, a percutaneous coronary angioplasty of the culprit lesion vessel (OM) was performed [Figure 2d] and a drug-coated stent was implanted, to minimize the need for dual oral antiplatelet treatment and to allow an eventual stepped surgical procedure on this patient. The procedure did not present complication and the patient remained asymptomatic.

An angio-computed tomography well showed the pathway of the fistulous communication between ascending aorta and RA [Figure 3c and d].

A multidisciplinary evaluation in heart team was carried on, which excluded indication to surgical closure of the fistula for two main reasons: (1) the presence of collateral vessels originating from the fistulous conduct and apparently furnishing the inferolateral wall, might have exposed a wide territory of the LV to the risk of ischemia; (2) the lack of pulmonary circulation overload or pulmonary systolic hypertension at right heart catheterization and the absence of heart failure symptoms. An intravascular ultrasound (IVUS)-guided percutaneous revascularization was performed [Figure 4a–e] with implantation of two everolimus-eluting stents with a modified T technique at the level of LM bifurcation and two bioabsorbable vascular scaffolds at mid-distal LAD. The procedure was successfully completed and the patient remained in good hemodynamic condition for the whole hospital stay and still asymptomatic, with a negative stress test at 6-month follow-up.

Figure 4

Angiographic result after percutaneous coronary intervention of left main and anterior descending artery (a and b) confirmed with intravascular ultrasound pullback that demonstrated correct sizing and good expansion of drug-eluting stents in left main (c), proximal anterior descending artery (d), and of overlapping bioabsorbable vascular scaffolds implanted in mid anterior descending artery (e)

DISCUSSION

A tunnel from aorta to RA is a very rare congenital anomaly, first described by Coto et al.[2] as a vascular link originating from the aortic root and terminating in the RA. Moreover, this congenital anomaly can be associated with a coronary artery anomaly.

In the reported cases, the tunnels originate mostly from the left sinus of Valsalva,[3456] more rarely from the right sinus of Valsalva or from the noncoronary sinus.[7]

AV fistulas can be either congenital or acquired, secondary to aneurysm formation, surgeries or interventions, infections, dissections, or posttraumatic. Clinical presentation varies from cardiogenic shock to a clinically asymptomatic continuous murmur, depending on the etiology of the fistula. The idiopathic forms of aorta-RA fistula are infrequently described in the literature. However, most of cases are treated with surgical repair or percutaneous technique in patients symptomatic for heart failure.[89]

In our report, the absence of an aneurysm, blunt chest trauma, or other noticeable pathology in the medical history allowed us to label the fistula as idiopathic. Moreover, the peculiarity of our case report is due to the presence of collateral coronary branches originating from the anomalous conduct which counter-indicated surgical closure of the fistula. This case represents both a diagnostic and therapeutic challenge, underlining the role of multimodality imaging approach with integration of angiography, echocardiography, IVUS, and angio-CT. The difficult choice of a percutaneous approach as the best therapeutic strategy for this patient was carried on by a multidisciplinary heart team which excluded surgical treatment of the fistula for the above-mentioned reasons.

CONCLUSIONS

We present a relatively rare case of congenital aortic-to-RA fistula furnishing coronary branches for the inferolateral wall of the LV, with associated diffuse coronary artery disease in a young patient. A multimodality imaging approach in the diagnostic phase and a multidisciplinary team-guided management represented the key points for a tailored therapeutic strategy on our patient.

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Conflicts of interest

There are no conflicts of interest.