Number 10-22: Anomalous Right Coronary Artery Arising from the Pulmonary Artery

Authors:  Ashish Kabra, MD, James K Wu MD, and Matthew W Martinez MD
Institution:  Lehigh Valley Health Network, Allentown, PA. USA

Background:  A 48 year old male was admitted with atypical chest pain and progressive shortness of breath over a three month period. His past medical history was significant for uncontrolled hypertension without other risk factors for coronary artery disease. The initial ECG illustrated left ventricular hypertrophy with ST-T wave changes compatible with repolarization abnormality (Figure 1). The Troponin I was elevated at 0.17.

Figure 1

He underwent adenosine myocardial perfusion imaging which demonstrated a moderate stress perfusion abnormality in the inferobasal wall (Figure 2).  This prompted a cardiac catheterization.

Figure 2

Aortography demonstrated the absence of a right coronary system but the presence of left coronary system (Figure 3).  Selective coronary angiography illustrated a dilated left coronary system with large collaterals to the right coronary territory (Figure 4).  A subsequent pulmonary angiogram showed constrast entering the right coronary artery from the main pulmonary trunk  (Figure 5 white arrow).

Figure 3

Figure 4

Figure 5

To further delineate the origin of the right coronary artery a cardiac MRI (CMR) was performed (Movie 1).  A 1.5 Tesla MRI scanner (Signa Twin Speed Excite, General Electric, Waukesha, WI, USA) was utilized to visualize the cardiovascular structures.  An ECG-gated steady state free precession (SSFP) pulse sequence [repetition time (TR) = 3.5 msec, echo time (TE) = 1.6 msec, temporal resolution = 40 msec, matrix 224x160, flip angle = 45˚, bandwidth=125 kHz, views per segment = 12] was performed to obtain cine images of the anomalous coronary artery (Figure 6 orange arrows).

Movie 1                                                    Figure 6 

Summary:  Anomalous right coronary artery of the pulmonary artery (ARCAPA) has an incidence quoted at 0.002% compared to its "sister" anomalous left coronary artery of the pulmonary artery (ALCAPA) quoted at 0.008%.¹ A recent article described 93 patients retrospectively reviewed from the case reports/series since 1950.² The authors concluded that the age of presentation of isolated ARCAPA ranged from 1 day to 90 years. Commonly, ARCAPA is diagnosed as an incidental finding and usually patients are asymptomatic. The presence of long term coronary steal into the pulmonary artery causes the anomalous right coronary to act as a venous conduit. This transfers blood from the normal coronary system to the pulmonary artery hence causing myocardial ischemia as evidenced in this case by chest pain, positive troponin and abnormal myocardial perfusion imaging within the territory of the right coronary artery.

Perspective:  The use of CMR for identification of anomalous coronary arteries was recently described in an expert consensus document.³ The main advantage of CMR over other imaging modalities is the absence of ionizing radiation and iodinated contrast media. CMR has also proven useful in case reports not only in initial diagnosis of coronary artery anomalies but follow up of surgical reimplantation, again reducing the need for ionizing radiation.⁴ In the above case, CMR proved helpful to delineate the course and origin of the right coronary artery for surgical planning.

References:
1. Williams IA, Gersony WM, Hellebrand WE. Anomalous right coronary artery arising from the pulmonary artery: a report of 7 cases and review of the literature. Am Heart J 2006;152:1004.e9-e17.

2. Modi H, Ariyachaipanich A, Dia M. Anomalous origin of right coronary artery from pulmonary artery and severe mitral regurgitation due to myxomatous mitral valve disease: a case report and literature review. J Invasive Cardiol. 2010 Apr;22(4):E49-55.

3. Hundley WG et al. ACCF/ACR/AHA/NASCI/SCMR 2010 Expert Consensus Document on Cardiovascular Magnetic Resonance. Circulation 2010;121:2462-2508.

4. Su JT, Krishnamurthy R, Chung T, Vick W, Kovalchin JP. Anomalous Right Coronary Artery from the Pulmonary Artery: Noninvasive Diagnosis and Serial Evaluation. J Cardiovasc Magn Reson 2007;9:57-61.

COTW Editor:  Kevin Steel

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