Introduction
Syncope, a common paroxysmal disorder in childhood, results from transient global cerebral hypoperfusion due to neurological, cardiovascular, or other causes. While most cases like vasovagal syncope have good prognosis, some causes, including arrhythmias or structural heart diseases, can lead to sudden death. Reference Zavala, Metais, Tuckfield, DelVecchio and Aronoff1 Abnormal vascular structures between the aorta and right atrium after the sinotubular junction are termed aorto-right atrial tunnels. These differ from sinus of Valsalva aneurysms originating from the sinus of Valsalva, and coronary-cameral fistulas with myocardial branch extensions. Reference Rad, Hijazi, Pouraliakbar, Mirzaaghayan and Zamani2 Aorto-right atrial tunnels can be asymptomatic or present with post-exertional dyspnoea, palpitations, and recurrent respiratory infections. Reference Sivakumar, Singhi, Sankarakuttalam and Rajendran3–Reference Jainandunsing, Linnemann and Bouma4 Syncope has not been reported as a presenting complaint. Therefore, this case aims to contribute to the literature by presenting the diagnostic and treatment process of an aorto-right atrial tunnel manifesting with recurrent syncope.
Case report
A patient presented with a one-year history of five emergency department admissions for syncope. The episodes were preceded by dizziness and visual blurring and were unrelated to exertion. Aside from these events, the patient had no additional symptoms, chronic illnesses, or medication use. Initial evaluation by Pediatric Neurology, including electroencephalography and cranial magnetic resonance imaging, was unremarkable, and the patient was referred to our clinic for suspected cardiac syncope. The physical examination was normal except for a continuous murmur heard on auscultation.
Echocardiography identified a tubular structure with a 9-mm ampullary dilation arising near the right coronary artery, following a U-shaped course, and draining into the right atrium. The right coronary artery was not well visualised. CT angiography demonstrated a fistulous tract originating from the aorta close to the right coronary sinus and draining into the right atrium, measuring 45 mm in length, with a proximal diameter of 6.5 mm, a distal diameter of 5 mm, and a 13-mm aneurysmal mid-portion. The right coronary artery was present but appeared hypoplastic (Figure 1).
( a ) U-shaped appearance of the aorto–right atrial connection on echocardiography. ( b and c ) CT angiography images.
The patient’s syncope was presumed secondary to transient cerebral hypoperfusion caused by steal phenomenon due to expansion of the aneurysmal fistula. Twenty-four-hour Holter monitoring and exercise stress testing showed no additional abnormalities. Transcatheter closure was planned.
During catheterisation, angiography confirmed a somewhat hypoplastic right coronary artery and a separate ostium giving rise to the tortuous extracardiac connection. Antegrade access was obtained. A 4 × 4-mm Amplatzer Duct Occluder II was advanced and deployed, with one disc positioned within the tract and the other in the atrium, successfully occluding the connection. Post-deployment angiography confirmed complete cessation of flow (Figure 2).
( a and b ) During contrast injection into the aorta, contrast passage into the right atrium through the aorto–right atrial connection is observed. The right coronary artery is also seen arising separately from the aorta. ( c and d ) After device closure of the connection, no contrast passage into the right atrium is observed.
At the three-month follow-up, the device remained stable, and the patient reported no further syncopal episodes.
Discussion
With this case report, we would like to emphasise that syncope, although rare, may occur in patients with aorto-right atrial connection. Aorto-right atrial tunnel was first described by Coto and colleagues in 1980. Reference Coto, Caffarena, Such and Marques5 Actually, Coto and colleagues defined this structure not as a “tunnel” but as a “connection.” This is because the term tunnel implies that this vascular structure courses within any structure. However, this structure courses as an extracardiac connection without any intramural course. Rad and colleagues compiled congenital aorto-cardiac connections in 2021 and proposed a new classification. Reference Rad, Hijazi, Pouraliakbar, Mirzaaghayan and Zamani2 According to this classification, the first distinction is made based on whether the connection structure is a hole or tubular. Sinus of Valsalva ruptures are classified as congenital aorto-cardiac connection Type 1 due to being a hole-like connection. Among tubular connections, coronary-cameral fistulas and coronary malformations with intramural coursing passages are classified as congenital aorto-cardiac connection Type 2. Among connections with extracardiac tubular-structured passages, aorto-ventricular connections are classified as Type 3A due to sharing a common wall with the aorta, while aorto-atrial connections are classified as Type 3B due to having completely independent extracardiac passages. This classification appears useful for better understanding since presenting similar cases in the literature under different terminologies creates confusion. The connection in our case also fits aorto-right atrial connection, namely congenital aorto-cardiac connection Type 3B, due to having no relationship with coronary vessels, being connected by an extracardiac tubular passage, and forming a U-shaped curve.
As in our case, when there is no coronary artery arising from the tubular structure, it is stated that the connection can be safely closed from both the aortic and atrial ends surgically or by transcatheter methods, and when closed only from the atrial end, the blind pouch will shrink over time. Reference Sivakumar, Singhi, Sankarakuttalam and Rajendran3,Reference de Winter, Blom and Straver6–Reference Sivakumar, Shahani and Francis7 Devices such as the Amplatzer Septal Occluder have proven their applicability for this purpose. Reference Jainandunsing, Linnemann and Bouma4 Our closure of this aorto-atrial connection from the atrial end via antegrade approach in this case supports the literature.
The main feature we want to emphasise in our case is that the patient’s presenting complaint was syncope. In most reviews, congenital aorto-cardiac connection is not even mentioned as a rare cause among paediatric cardiac syncope causes. Reference Zavala, Metais, Tuckfield, DelVecchio and Aronoff1,Reference Shen, Sheldon and Benditt8–Reference Massin, Malekzadeh-Milani and Benatar9 The reason for this is the assumption that aorto-cardiac connections can only cause significant diastolic regurgitation in the ascending aorta and lead to carotid steal phenomenon if they steal a large volume from the aortic root. Reference Aggarwal, Sai and Iyer10 The literature has so far justified this assumption. However, it should not be forgotten that this tubular structure is a vascular structure and can dilate, which can lead to diastolic regurgitation in the aorta and thus steal phenomenon. Our case shows that while coronary-cameral fistulas among congenital aorto-cardiac connections having small calibrations and aorto-ventricular connections are less likely to cause syncope through this mechanism due to the pressure load they face, aorto-atrial connections can cause syncope.
Conclusions
In conclusion, this case demonstrates that aorto-right atrial connection, which is quite rarely seen, can cause syncope, should be considered when a continuous murmur is heard on cardiac auscultation in patients presenting with syncope complaints, and a paediatric cardiology consultation should be requested. In patients with aorto-right atrial connection, transcatheter closure is a highly effective and reliable method.
Financial support
This case report received no specific grant from any funding agency, commercial, or not-for-profit sectors.
Competing interests
The authors declare none.
Ethical standard
The authors declare that this case report complies with ethical standards.
