Nigerian Journal of Cardiology

: 2017  |  Volume : 14  |  Issue : 2  |  Page : 103--105

Stress-induced ischemia caused by conus branch of right coronary to right atrial coronary cameral fistula during treadmill test

Ramachandra Barik 
 Department of Cardiology, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India

Correspondence Address:
Ramachandra Barik
Department of Cardiology, All India Institute of Medical Sciences, Bhubaneswar, Odisha


A 28-year-old apparently healthy young male working in Border Security Force referred to our institute for annual master health checkup. The routine biochemical tests, 12-lead electrocardiogram (EKG), chest X-ray, and echo were normal. His exercise ECG was remarkable for significant horizontal ST depression in lead I, AVL, V4–V6 during treadmill test at 15 METs. He had usual breathlessness during exercise. Coronary angiogram revealed conus branch of right coronary artery to right atrial coronary cameral fistula draining into right atrium which may be an unusual reason for inducible ischemia at high-intensity exercise as the other coronary arteries were normal. He is now under regular follow-up for need–based, catheter-based intervention in the future because of asymptomatic presentation and small size fistula. A period of 12-month follow-up was uneventful.

How to cite this article:
Barik R. Stress-induced ischemia caused by conus branch of right coronary to right atrial coronary cameral fistula during treadmill test.Nig J Cardiol 2017;14:103-105

How to cite this URL:
Barik R. Stress-induced ischemia caused by conus branch of right coronary to right atrial coronary cameral fistula during treadmill test. Nig J Cardiol [serial online] 2017 [cited 2023 Jan 30 ];14:103-105
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Full Text


Independent conus artery or conus branch of right coronary is seen in ≥90% of computed tomographic coronary angiogram (CT-CAG).[1] It is important for cardiothoracic surgeons because it crosses right ventricular outflow tract [2] and it is important to cardiologists because it forms Vieussens arterial ring.[3],[4],[5] Conus artery or conus branch very rarely forms coronary cameral fistula (CCF).[6] It may present as exertional angina due to coronary steal.[7] It is very rare or has not been reported to have exercise-induced ischemia during treadmill test due to CCF.[8] The interesting finding in this case report is that incidental detection of conus artery CCF to right atrium causing significant horizontal ST depression in chest lead even though the patient was clinically asymptomatic which is a usual feature of the most of the CCF.[9]

 Case Report

A 28-year-old male, working as an armed Border Security Force (BSF) appeared for annual fitness checkup. He was asymptomatic in routine life and during duty. There was no history of cardiac illness. Body mass index was 25.4 kg/m 2. His clinical examination including cardiovascular system examination was normal. There was no room air desaturation. Routine tests such as blood sugar, lipid profile, thyroid function, and renal function were normal. Chest X-ray and echocardiography were normal. A 12-lead electrocardiogram (EKG) suggested minor T-wave inversion in lead III. Exercise EKG during treadmill test showed more than 2 mm horizontal ST depression in V4–V6 at 15 METs with usual breathlessness without any angina and/or syncope. He was suggested CT-CAG to rule out the possibility of congenital coronary anomaly. Immediately, CT-CAG could not be done due to technical reason in our institution. Therefore, a routine CAG was performed using right radial approach. CAG revealed normal and dominant left coronary artery [Figure 1]. There was difficulty in selective hooking of the nondominant right coronary artery because of repeated interference of conus branch [Figure 2]. Inadvertently, the selective and deep engagement of tiger catheter into conus branch disclosed the conus branch to right atrial CCF [Video 1]. The fistula was opening exactly opposite to the opening of the coronary sinus. Then, right coronary artery was selectively hooked with deep engagement showed as if the right coronary artery is normal [Figure 3]. He was discharged on the same day after 4 h of uneventful observation.{Figure 1}{Figure 2}{Figure 3}


He was instructed to continue his duty in BSF because of the asymptomatic presentation, incidental detection during annual health checkup, and small size of the fistula. A period of 12-month follow-up was uneventful.


Most of the patients of CCF are detected incidentally during evaluation for other illness.[10] The intensity of murmur in CCF may vary from Grade II to VI depending on the size of the shunt.[9] Therefore, there was no murmur during auscultation because of small shunt. Coronary CT angiography is extremely useful for atypical chest pain and low and/or intermediate probability for coronary artery disease in treadmill test.[11] In this case, a CT-CAG would have served better [12] which could not be done because of technical issue. A hemodynamic study to pinpoint the shunt size could have been done, but we did not feel it is necessary because of obvious small size of shunt (asymptomatic and clinically no murmur). Recommendations for CCF with asymptomatic presentation are variable. Some authors recommend that even small CCF should be treated to prevent future complications.[13] In some other studies, the long-term regular follow-up of cases with small CCF is usually uneventful.[14] There is a Class IIa recommendation that transcatheter occlusion is reasonable for the management of patients with moderate or large coronary artery fistula without clinical symptoms (level of evidence: C),[15] whereas all the large fistula should be closed by surgery irrespective of shunt size and asymptomatic patients with insignificant shunts should followed up.[14]


Core tip: Conus branch of right coronary artery or conus artery directly arising from anterior sinus has been implicated in supporting collaterals to the left anterior descending coronary artery through Vieussens' arterial ring. It is rarely reported that a conus branch of right coronary artery to right atrial fistula can be the reason for significant ST depression during exercise EKG test. This is a rare and interesting case report, wherein an asymptomatic young adult when was undergoing master health checkup, incidentally found to have conus branch of right coronary artery to right atrial CCF responsible for exercise-induced ischemia at high-intensity exercise.

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