Ischemia or ischaemia is a restriction in blood supply to tissues,
causing a shortage of oxygen that is needed for cellular metabolism
(to keep tissue alive).
Ischemia is generally caused by problems
with blood vessels, with resultant damage to or dysfunction of tissue.
It also means local anemia in a given part of a body sometimes
resulting from congestion (such as vasoconstriction, thrombosis or
Ischemia comprises not only insufficiency of oxygen, but
also reduced availability of nutrients and inadequate removal of
Ischemia can be partial (poor perfusion) or total.
1 Signs and symptoms
1.1 Cardiac ischemia
5 Society and culture
6 Etymology and pronunciation
7 See also
Signs and symptoms
Since oxygen is carried to tissues in the blood, insufficient blood
supply causes tissue to become starved of oxygen. In the highly
metabolically active tissues of the heart and brain, irreversible
damage to tissues can occur in as little as 3–4 minutes at body
temperature. The kidneys are also quickly damaged by loss of blood
flow (renal ischemia). Tissues with slower metabolic rates may undergo
irreversible damage after 20 minutes.
Clinical manifestations of acute limb ischemia (which can be
summarized as the "six P's") include pain, pallor, pulseless,
paresthesia, paralysis, and poikilothermia.
Without immediate intervention, ischemia may progress quickly to
tissue necrosis and gangrene within a few hours.
Paralysis is a very
late sign of acute arterial ischemia and signals the death of nerves
supplying the extremity.
Foot drop may occur as a result of nerve
damage. Because nerves are extremely sensitive to hypoxia, limb
paralysis or ischemic neuropathy may persist after revascularization
and may be permanent.
See also: Myocardial infarction
Cardiac ischemia may be asymptomatic or may cause chest pain, known as
angina pectoris. It occurs when the heart muscle, or myocardium,
receives insufficient blood flow. This most frequently results from
atherosclerosis, which is the long-term accumulation of
cholesterol-rich plaques in the coronary arteries. Ischemic heart
disease is the most common cause of death in most Western countries
and a major cause of hospital admissions.
Both large and small bowel can be affected by ischemia.
the large intestine may result in an inflammatory process known as
Ischemia of the small bowel is called mesenteric
Main article: Stroke
Brain ischemia is insufficient blood flow to the brain, and can be
acute or chronic. Acute ischemic stroke is a neurologic emergency that
may be reversible if treated rapidly. Chronic ischemia of the brain
may result in a form of dementia called vascular dementia. A brief
episode of ischemia affecting the brain is called a transient ischemic
attack (TIA) often called a mini-stroke.
Main article: Acute limb ischaemia
Lack of blood flow to a limb results in acute limb ischemia.
Cyanosis and Gangrene
Reduced blood flow to the skin layers may result in mottling or
uneven, patchy discoloration of the skin
Ischemia is a vascular disease involving an interruption in the
arterial blood supply to a tissue, organ, or extremity that, if
untreated, can lead to tissue death. It can be caused by embolism,
thrombosis of an atherosclerotic artery, or trauma.
like venous outflow obstruction and low-flow states can cause acute
arterial ischemia. An aneurysm is one of the most frequent causes of
acute arterial ischemia. Other causes are heart conditions including
myocardial infarction, mitral valve disease, chronic atrial
fibrillation, cardiomyopathies, and prosthesis, in all of which
thrombi are prone to develop.
The thrombi may dislodge and may travel anywhere in the circulatory
system, where they may lead to pulmonary embolus, an acute arterial
occlusion causing the oxygen and blood supply distal to the embolus to
decrease suddenly. The degree and extent of symptoms depend on the
size and location of the obstruction, the occurrence of clot
fragmentation with embolism to smaller vessels, and the degree of
peripheral arterial disease (PAD).
Thromboembolism (blood clots)
Embolism (foreign bodies in the circulation, e.g. amniotic fluid
Traumatic injury to an extremity may produce partial or total
occlusion of a vessel from compression, shearing, or laceration. Acute
arterial occlusion may develop as a result of arterial dissection in
the carotid artery or aorta or as a result of iatrogenic arterial
injury (e.g., after angiography).
An inadequate flow of blood to a part of the body may be caused by any
of the following:
Thoracic outlet syndrome
Thoracic outlet syndrome (compression of the brachial plexus)
Atherosclerosis (lipid-laden plaques obstructing the lumen of
Hypoglycemia (lower than normal level of glucose)
Tachycardia (abnormally rapid beating of the heart)
Hypotension (low blood pressure, e.g. in septic shock, heart failure)
Outside compression of a blood vessel, e.g. by a tumor or in the case
of superior mesenteric artery syndrome
Sickle cell disease
Sickle cell disease (abnormally shaped red blood cells)
Induced g-forces which restrict the blood flow and force the blood to
the extremities of the body, as in acrobatics and military flying
Localized extreme cold, such as by frostbite or improper cold
An increased level of glutamate receptor stimulation
Arteriovenous malformations, and peripheral artery occlusive disease
rupture of significant blood vessels supplying a tissue or organ.
Anemia vasoconstricts the periphery so that red blood cells can work
internally on vital organs such as the heart, brain, etc., thus
causing lack of oxygen to the periphery.
Premature discontinuation of any oral anticoagulant.
Unconsciousness, such as due to the ingestion of excessive doses of
central depressants like alcohol or opioids, can result in ischemia of
the extremities due to unusual body positions that prevent normal
Native records of contractile activity of the left ventricle of
isolated rat heart perfused under Langendorff technique. Curve A -
contractile function of the heart is greatly depressed after
ischemia-reperfusion. Curve B - a set of short ischemic episodes
(ischemic preconditioning) before prolonged ischemia provides
functional recovery of contractile activity of the heart at
Main article: Ischemic cascade
Ischemia results in tissue damage in a process known as ischemic
cascade. The damage is the result of the build-up of metabolic waste
products, inability to maintain cell membranes, mitochondrial damage,
and eventual leakage of autolyzing proteolytic enzymes into the cell
and surrounding tissues.
Restoration of blood supply to ischemic tissues can cause additional
damage known as reperfusion injury that can be more damaging than the
initial ischemia. Reintroduction of blood flow brings oxygen back to
the tissues, causing a greater production of free radicals and
reactive oxygen species that damage cells. It also brings more calcium
ions to the tissues causing further calcium overloading and can result
in potentially fatal cardiac arrhythmias and also accelerates cellular
self-destruction. The restored blood flow also exaggerates the
inflammation response of damaged tissues, causing white blood cells to
destroy damaged cells that may otherwise still be viable.
Early treatment is essential to keep the affected limb viable. The
treatment options include injection of an anticoagulant, thrombolysis,
embolectomy, surgical revascularisation, or amputation. Anticoagulant
therapy is initiated to prevent further enlargement of the thrombus.
Continuous IV unfractionated heparin has been the traditional agent of
If the condition of the ischemic limb is stabilized with
anticoagulation, recently formed emboli may be treated with
catheter-directed thrombolysis using intraarterial infusion of a
thrombolytic agent (e.g., recombinant tissue plasminogen activator
(tPA), streptokinase, or urokinase). A percutaneous catheter inserted
into the femoral artery and threaded to the site of the clot is used
to infuse the drug. Unlike anticoagulants, thrombolytic agents work
directly to resolve the clot over a period of 24 to 48 hours.
Direct arteriotomy may be necessary to remove the clot. Surgical
revascularization may be used in the setting of trauma (e.g.,
laceration of the artery).
Amputation is reserved for cases where limb
salvage is not possible. If the patient continues to have a risk of
further embolization from some persistent source, such as chronic
atrial fibrillation, treatment includes long-term oral anticoagulation
to prevent further acute arterial ischemic episodes.
Decrease in body temperature reduces the aerobic metabolic rate of the
affected cells, reducing the immediate effects of hypoxia. Reduction
of body temperature also reduces the inflammation response and
reperfusion injury. For frostbite injuries, limiting thawing and
warming of tissues until warmer temperatures can be sustained may
reduce reperfusion injury.
Society and culture
The Infarct Combat Project (ICP) is an international nonprofit
organization founded in 1998 to fight ischemic heart diseases through
education and research.
Etymology and pronunciation
The word ischemia (/ɪsˈkiːmiə/) is from Greek ἴσχαιμος
iskhaimos, "staunching blood" from ἴσχω iskhο, "keep back,
restrain" and αἷμα haima, "blood".
Trauma triad of death
Ischemia-reperfusion injury of the appendicular musculoskeletal system
OED 2nd edition, 1989.
^ Entry "ischemia" in Merriam-Webster Online Dictionary.
^ Merck & Co. Occlusive Peripheral Arterial Disease, The Merck
Manual Home Health Handbook website, revised and updated March 2010.
Retrieved March 4, 2012.
^ Vascular and Interventional Radiology: The Requisites (2nd Edition),
John A. Kaufman & Michael J. Lee, Publisher:Elsevier - Active as
^ a b c d e f g Lewis. S.L (2008). Medical-Surgical Nursing (7th ed.).
Vascular disorder. pp. 907–908.
^ World Health Organization Department of Health Statistics and
Informatics in the Information, Evidence and Research Cluster (2004).
The global burden of disease 2004 update. Geneva: WHO.
^ Sims N.R.; Muyderman H. (2010). "Mitochondria, oxidative metabolism
and cell death in stroke". Biochimica et Biophysica Acta. 1802 (1):
80–91. doi:10.1016/j.bbadis.2009.09.003. PMID 19751827.
^ Infarct Combat Project website; accessed October 26, 2015.
Elizabeth (editor). Oxford Reference: Concise Medical Dictionary
(1990, 3rd ed.). Oxford University Press: Market House Books, 1987,
2nd ed., pg. 107, ISBN 0-19-281991-7, ISBN 978-0-19-281991-8
Principles of pathology
Programmed cell death
Oral and maxillofacial pathology
Fluorescence in situ hybridization
Disorders of blood flow
Renal vein thrombosis
Ischaemic heart disease
large intestine: Ischemic colitis
small intestine: Mesenteric ischemia