1 Definitions & morphology
| Term | Diameter rule | Length / extent |
|---|---|---|
| Coronary artery aneurysm | > 1.5× the normal adjacent segments | Width > length; involves < 50% of the vessel’s total length |
| Coronary artery ectasia | > 1.5× the normal adjacent segments | Length > width; involves > 50% of the vessel’s total length |
- Shape. Aneurysms are either fusiform (longitudinal > transverse diameter) or saccular (transverse > longitudinal diameter).
- “Giant” aneurysm. > 2–15 cm in adults; > 8 mm in children.
- True aneurysm vs. pseudoaneurysm. A true aneurysm’s walls consist of all three layers (intima, media, adventitia). A pseudoaneurysm has ≤ 2 intact walls and is frequently secondary to chest trauma or catheter-based interventions.
2 Etiologies
Typically affects the RCA most frequently, followed by the LAD, LCx, and left main.
A self-limited small- and medium-vessel vasculitis seen in young children (6 months to 5 years). Without treatment, 15–25% of affected children develop coronary artery aneurysms — most commonly involving the left main and proximal segments.
Takayasu arteritis · connective tissue diseases (SLE, Marfan, Behçet) · mycotic emboli · cocaine use · congenital defects.
3 Imaging
ECG-gated CCTA is considered the best imaging tool and the modality of choice. It excels at:
- Aneurysm morphology
- Detecting concurrent thrombosis, stenosis, or dissection
- Identifying calcification — frequently present within atherosclerotic aneurysms and chronic Kawasaki cases
Diagnostic pitfall: both CT and invasive angiography can underestimate the true size of the aneurysm if a mural thrombus or dissection flap is present along the vessel wall.
Cardiac MR is often preferred when long-term surveillance is required (no repeated radiation), though it struggles to detect calcifications, and stents or clips may degrade image quality.
4 Clinical presentation & management
- Most patients (75–80%) are asymptomatic. Aneurysms are often found incidentally, present in roughly 5% of angiograms.
- Complications. Sluggish blood flow → thrombosis → acute MI. Keep coronary artery aneurysms high on the differential for patients < 20 years old presenting with angina or acute MI. Rupture is rare but catastrophic.
- Treatment. Anticoagulants and antiplatelets in stable cases. Enlarging or ruptured aneurysms warrant surgical or percutaneous intervention (e.g. covered coronary stent). For pediatric Kawasaki disease, IVIG and aspirin are the primary treatments to prevent or regress aneurysm formation.