CTICasesCrisscross Coronary Ostia Variant
Imaging findings
Cardiac CT demonstrates separate origins of the left anterior descending and circumflex arteries from the left coronary sinus, but with an unusual crossing configuration: the left circumflex arises more anteriorly and crosses over the LAD, which arises more posteriorly and inferiorly from the left coronary sinus. The two vessels crisscross each other at their proximal segments before taking their normal courses.
Key takeaways
Crisscross coronary ostia is a rare incidental variant in which the left anterior descending and circumflex arteries both arise from the left coronary sinus but with their origins inverted relative to normal, causing the proximal segments to cross each other. This anatomical curiosity carries no clinical significance but is important to recognize on coronary CT angiography to avoid misinterpretation as anomalous origin or malignant coronary variant. Careful tracing of each vessel from its origin to its distal course establishes the diagnosis.
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