Pathology after angioplasty, stents and grafts
- Process
Opening or replacing a narrowed artery injures it again; clots and new scar tissue can close it.
What it is
Balloon angioplasty and stenting open narrowed arteries by breaking and stretching the plaque, which injures the wall. Early failure comes from thrombosis on the injured surface or the stent; later failure from in-stent restenosis, a proliferation of smooth-muscle cells and matrix (neointimal hyperplasia). Drug-eluting stents release antiproliferative agents that reduce restenosis but delay endothelial coverage, so late stent thrombosis is a concern. Vein grafts develop intimal thickening and later atherosclerosis; arterial grafts (internal mammary artery) last longer.
Structure
- In-stent restenosis: stent struts surrounded by a thick layer of smooth-muscle cells in a proteoglycan-rich matrix, covered by endothelium.
- Vein graft: concentric intimal fibromuscular thickening; later atheromas with necrotic cores.
Step by step
- The balloon or stent expands the artery, cracking the plaque and denuding the endothelium.
- Platelets and fibrin deposit on the injured surface and on stent struts.
- Inflammation and growth factors activate medial smooth-muscle cells.
- Smooth-muscle cells migrate, proliferate and make matrix inside the stent.
- The new endothelium covers the struts; excessive neointima narrows the lumen again.
Failure modes after revascularisation
| Problem | When | Mechanism |
|---|---|---|
| Acute occlusion | Hours to days | Dissection or thrombosis on the injured wall |
| Stent thrombosis | Early, or late with drug-eluting stents | Exposed struts without endothelium |
| In-stent restenosis | Months | Neointimal hyperplasia (smooth-muscle cells and matrix) |
| Vein graft disease | Years | Intimal thickening, then atherosclerosis in the graft |
Clinical notes
- Recurrent angina months after stenting suggests restenosis; sudden infarction suggests stent thrombosis.
Test yourself
Think of the answer, then tap the question to see it.
What tissue causes in-stent restenosis?
Neointimal hyperplasia: proliferating smooth-muscle cells and extracellular matrix inside the stent.
Why do drug-eluting stents raise concern about late thrombosis?
The antiproliferative drug slows endothelial coverage of the struts, leaving thrombogenic metal exposed longer.
Which bypass conduit stays open longest?
The internal mammary (internal thoracic) artery, compared with saphenous vein grafts.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Angioplasty and stent placement - heart: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.