Transseptal coronary course

Last revised by Joachim Feger on 1 Aug 2023

A transseptal, intraseptal or subpulmonic course refers to a coronary artery passing anteriorly and inferiorly to the aortic valve in a subpulmonic route through the interventricular septal myocardium and is mostly described as a ‘benign anomalous course’ without hemodynamic significance.

Clinical conditions associated with a transseptal course of a coronary artery include 1-3:

Similar to a retroaortic course a transseptal course is often not of increased hemodynamic risk especially if subpulmonic and might be found incidentally on invasive coronary angiography (ICA),  cardiac CT or cardiac MRI. Other conceivable symptoms include angina or arrhythmia 4.

A transseptal or intraseptal course is usually associated with an ectopic origin of either the left anterior descending artery, left main coronary artery or right coronary artery. It can be depicted in coronary CTA or coronary MRA or invasive coronary angiography (ICA) as a major coronary artery coursing through the interventricular septum 1-4.

Features indicating a transeptal course versus an interarterial course include the following 1:

  • artery surrounded by the myocardium of the interventricular septum

  • a downward course below the crista supraventricularis (hammock sign)

  • no slitlike or oblong orifice

The radiology report should include a description of the following features:

A retroaortic course is considered benign and not of hemodynamic importance. Management will entirely depend on symptoms and associated findings.  However, it can complicate aortic valve surgery 1.

A condition that can mimic the radiological appearance of a transseptal course is an interarterial course, the latter is associated with an increased risk of sudden cardiac death 1,2.

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3
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