Interarterial course of the right coronary artery

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incidental cardiac disease on thoracic CT: what the general radiologist needs to know. Axial contrast enhanced CT demonstrates the RCA (black arrow) arising from the left coronary cusp in a 43-year-old female being evaluated for hoarseness and vocal cord paralysis. Ao aorta, PA pulmonary artery
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Interarterial course of the right coronary artery, may occur if the right coronary artery (RCA) has an aberrant origin from the left coronary sinus. The interarterial course occurs because the artery passes between the ascending aorta and the pulmonary trunk.

It is an uncommon anatomic variant with a potential risk of cardiac ischemia, hence its alternative monicker, malignant course of the right coronary artery.

Pathology

When the right coronary artery arises aberrantly in this manner, there are three possible courses it may take:

  • interarterial with intramural segments: highest risk
  • interarterial and extramural
  • interatrial

Treatment and prognosis

Some think that this anomaly carries an increased risk of cardiac ischemia, myocardial infarction, and possibly sudden death. Others consider the aberrant course of the right coronary artery to be less concerning than an aberrant course of the left coronary artery. Repair strategies vary depending on the institution's level of concern.

The cause of ischemia from this anomaly is not completely understood. Classically, extrinsic compression of the coronary artery between the aortic root and the right ventricular outflow tract was considered to be the primary problem, but there is increasing evidence that the risk may be mostly due to the anomalous coronary artery's flow-limiting 'slit'-like orifice.

The highest risk situation is considered to be the interarterial course with segments that course through the wall of the aorta.

See also