3D-printed visualization of a double right coronary artery with intra-atrial course

A 55-year-old male patient with atypical angina, dyspnoea, elevated cardiovascular risk (hypertension, hypercholesteremia, smoker, obesity) and a non-conclusive stress echocardiography was referred for computed tomography coronary angiography (CTCA). There was moderate coronary calcification (Calcium Score 8 (Agatston), 50. percentile) without obstructive coronary artery disease (all segments < 50%). However, CTCA showed various coronary anomalies with potential clinical impact (Fig. 1, video 1–5): the right coronary artery (RCA) originated from the right coronary cusp and early trifurcated in a right ventricular branch and an anterior and posterior double RCA, both running in the right atrioventricular groove. The posterior mid RCA then penetrated the right atrial (RA) wall at the ostium of the right atrial appendage and exhibited an intracavitary course of 40 mm (Panel 1). After the exit from RA, both RCAs re-united in anastomosis. Additionally, the apical left anterior descending coronary artery (LAD) had an 8 mm intracavitary course within the apical right ventricle. Correlation of these incidental findings with the atypical chest discomfort was deemed as unlikely, especially because there were no significant coronary stenoses. Therefore, a conservative approach with optimal secondary prevention was recommended. To the best of our knowledge, this is the first description of this combined coronary artery anomaly with potential clinical implications.

A 55-year-old male patient with atypical angina, dyspnoea, elevated cardiovascular risk (hypertension, hypercholesteremia, smoker, obesity) and a non-conclusive stress echocardiography was referred for computed tomography coronary angiography (CTCA). There was moderate coronary calcification (Calcium Score 8 (Agatston), 50. percentile) without obstructive coronary artery disease (all segments < 50%). However, CTCA showed various coronary anomalies with potential clinical impact (Fig. 1, video 1-5): the right coronary artery (RCA) originated from the right coronary cusp and early trifurcated in a right ventricular branch and an anterior and posterior double RCA, both running in the right atrioventricular groove. The posterior mid RCA then penetrated the right atrial (RA) wall at the ostium of the right atrial appendage and exhibited an intracavitary course of 40 mm (Panel 1). After the exit from RA, both RCAs re-united in anastomosis. Additionally, the apical left anterior descending coronary artery (LAD) had an 8 mm intracavitary course within the apical right ventricle. Correlation of these incidental findings with the atypical chest discomfort was deemed as unlikely, especially because there were no significant coronary stenoses. Therefore, a conservative approach with optimal secondary prevention was recommended. To the best of our knowledge, this is the first description of this combined coronary artery anomaly with potential clinical implications.

Discussion
Double RCA and intracavitary coronary course are extremely rare anomalies. Prevalence of intracavitary coronary course was initially reported to be very low at 0.1% [1], but contemporary studies point towards higher numbers (1.3% [2] to 1.8% [3]). Initial prevalence was presumably underestimated as detection during bypass surgery or using 2D invasive coronary angiography is difficult. Given the increasing use of advanced cardiac imaging such as CTCA, its true prevalence is likely to increase even further.
Although they are usually clinically benign, these anatomic variants may impose myriad of clinical challenges around invasive cardiac procedures, in particular if unrecognized prior to the procedure: (1) in the setting of interventional or cardiovascular surgical revascularization leading to difficulties in vessel localization as well as bypass grafting; (2) right heart catheterization leading to potential injury of the vessel; and (3) in case of electrophysiological procedures such as catheter ablation or lead device implantation. Lead device implantation at the right atrial wall or right ventricular apex in these patients could directly damage coronary arteries with intracavitary course and lead to inadvertent disruption of the vessel.
At the current time, AHA and ESC guidelines do not cover specific recommendations for such patients. Therefore, management should be tailored to the individual patient.
3D printing is an excellent tool to demonstrate such complex anomalies to the patients affected and to colleagues who are not familiar with advanced cardiac imaging (Fig. 2,  video 3). Knowledge of such cases can increase the awareness for coronary anomalies which can be a potential harm for patients during invasive cardiac procedures.
Funding Open access funding provided by University of Basel. There was no funding for this article.Conflict of interest There is no conflict of interest to declare.

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