Discussion

Congenital aorta–atrial tunnel, first described by Coto et alReference Coto, Caffarena, Such and Marques ¹ in 1980, is an extracardiac congenital communication between the right atrium and the aorta. The most postulated mechanism for aorta–right atrial tunnel is aortic elastic lamina media deficiency.Reference Gajjar, Voleti, Matta, Iyer, Dash and Desai ⁴ The term aorta–atrial fistula is also used especially for secondary cases. It is hard to discriminate tunnel from coronary–cameral fistula. Generally, a tunnel differs from fistula in that it does not have myocardial branches.Reference Rosenberg, Williams and Trusler ² In addition, the differentiation between a tunnel and sinus Valsalva aneurysm must be made. A tunnel originates above the supra-aortic ridge, whereas sinus Valsalva aneurysm is located under the ridge.Reference Sreedharan, Baruah and Dash ^{5 ,} Reference Golzari and Riebman ⁶ In our case, normal coronary artery anatomy was revealed by angiocardiography and there were no side branches originating from the tunnel. Therefore, the presence of normal major coronary arteries and absence of any small myocardial coronary branches from the tunnel argues against the structure being a coronary–cameral fistula and supports the diagnosis of aorta–right atrial tunnel.

Volume overload may happen in both ventricles if there is a critical shunt from left to right, and as a consequence exercise dyspnoea, tachycardia, chest pain, and recurrent pulmonary infections may be seen. Moreover, patients may be asymptomatic.Reference Gajjar, Voleti, Matta, Iyer, Dash and Desai ⁴ Our patient did not have any obvious symptoms and most of the cases in the literature were asymptomatic. Except for one of the published cases, all of the patients had a continuous murmur on the right side of the sternum, as was the case in our patient.

Although aorta–right atrial tunnel can be determined by transthoracic echocardiography, diagnosis may be confirmed by aortography and selective coronary angiocardiography. In our case, colour Doppler demonstrated a tunnel extending from the left aortic sinus to the right atrium.

Left coronary sinus aneurysm is the rarest type of coronary sinus aneurysms (1%), and when it occurs it can lead to rupture in adjacent structures such as the left ventricle, pulmonary artery, myocardium, and epicardium.Reference Chu, Hung, How, Chang and Wang ⁷ In our case, there was a communication originating from the left coronary sinus and passing behind the aorta to the right atrium. Hence, this communication was not thought to be rupture of a sinus Valsalva aneurysm.

Even though patients are asymptomatic, when the diagnosis is made it should be closed as soon as possible. The reason for this is to avoid the potential risk of emboli, spontaneous rupture thrombosis, aneurysm formation, infective endocarditis, pulmonary vascular disease, coronary failure, aortic insufficiency, and calcification on the wall of the tunnel.Reference Coto, Caffarena, Such and Marques ^{1 ,} Reference Kalangos, Beghetti, Vala, Chraibi and Faidutti ⁸ In addition, the surgical mortality risk increases for the patients who are not treated until advanced ages.

Treatment options include transcatheter closure, ligation of the tunnel under controlled hypotension, and surgical closure under total cardiopulmonary bypass.Reference Sreedharan, Baruah and Dash ⁵ The transcatheter closure technique is safer because of the lower risk of artery, vein, and nerve injuries, infection problems, rhythm problems, hypoxia, and cosmetic problems. To the best of our knowledge, 17 cases have been reported in the literature; two of them were closed by transcatheter technique – both were paediatric patients – 14 of them were closed by surgery, and one of them was accepted for clinic monitoring. Sreedharan et alReference Sreedharan, Baruah and Dash ⁵ were the first to report a case in which the tunnel was embolised using two units of coil with transcatheter technique in an 11-year-old patient in 2006. Mahesh et alReference Mahesh, Francis and Kumar ⁹ reported a case of transcatheter closure of an aorta–right atrial tunnel using coil for a 4-day-old baby. We presented a case of this rare disease and percutaneous application – successful closure of the tunnel using an Amplatzer^® vascular plug 4 with the transcatheter technique. Using coil may be preferred because it is an inexpensive and simple technique, but the length and diameter of the tunnel led us to select the Amplatzer^® vascular plug 4, because the coil may have migrated to the right atrium because of the large distal end of the tunnel. In addition, the design and the softness of the Amplatzer^® vascular plug 4 was suitable for this particular case.