ischemia
Meaning of ischemia: A shortfall of blood supply to tissue, leaving it with too little oxygen for its needs.
Definition of ischemia
Ischemia is a reduction in blood flow to a tissue or organ that leaves it with less oxygen and fewer nutrients than it requires. It usually results from a narrowed or blocked artery, and the consequences depend on how severe the restriction is, how quickly it develops and how well the tissue tolerates oxygen shortage.
How it develops
Most ischemia begins with a narrowed artery, commonly from atherosclerosis, where fatty plaque builds up in the vessel wall. Flow may be adequate at rest but fall short when demand rises, which is why symptoms often appear on exertion first. A clot forming on a ruptured plaque, or an embolus traveling from elsewhere, can block the vessel abruptly instead.
What it is called in different tissues
| Site | Typical manifestation |
|---|---|
| Heart muscle | Angina; myocardial infarction if flow is lost |
| Brain | Transient ischemic attack, or ischemic stroke |
| Limbs | Claudication, pain on walking that eases with rest |
| Intestine | Mesenteric ischemia, pain disproportionate to examination findings |
Ischemia is not infarction
The distinction matters clinically. Ischemia describes inadequate blood supply, and tissue can recover fully if flow is restored in time. Infarction describes tissue that has already died from that shortage, which is irreversible. Ischemia precedes infarction, and the window between them is what makes early treatment worthwhile.
Used in a sentence
The electrocardiogram showed changes consistent with cardiac ischemia during the episode of chest pain.
Good to know
Ischemia refers to reduced blood flow and is distinct from infarction, which describes the tissue death that follows if ischemia is severe or prolonged enough.
Word origin
Where “ischemia” comes from
Formed from Greek ischein, meaning to hold back or restrain, and haima, meaning blood.