Stunning follows restored flow; hibernation persists with reduced flow
Expansion
| Feature | Stunning | Hibernation |
|---|---|---|
| Blood flow | Normal (restored) | Reduced (chronic) |
| Duration | Hours to days | Chronic |
| Trigger | Acute ischaemia then reperfusion | Persistent hypoperfusion |
| Recovery | Spontaneous, with time | After revascularisation |
Stunning is prolonged contractile dysfunction after a brief ischaemic episode despite restored perfusion, attributed to calcium overload and free radical injury. It is seen after thrombolysis, angioplasty and cardiopulmonary bypass.
Hibernation is a chronic adaptive downregulation of contraction to match reduced supply, protecting the tissue from infarction.
Both are viable tissue, which distinguishes them from scar. Identifying viability matters because revascularising hibernating myocardium improves function, whereas revascularising scar does not. Viability is assessed with dobutamine stress echocardiography (contractile reserve), cardiac magnetic resonance (late gadolinium enhancement) or nuclear perfusion and metabolism imaging.
A related protective phenomenon is ischaemic preconditioning, where brief ischaemic episodes render myocardium more resistant to a subsequent prolonged insult.