Infarction
Encyclopedia
In medicine
, infarction refers to tissue death (necrosis
) that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.
may be blocked by an obstruction (e.g. an arterial embolus, thrombus
, or atherosclerotic plaque), may be mechanically compressed (e.g. tumor
, volvulus
, or hernia
), ruptured by trauma (e.g. atherosclerosis
or vasculitides), or vasoconstricted (e.g. cocaine vasoconstriction leading to myocardial infarction
).
Hypertension
and atherosclerosis
are risk factors for both atherosclerotic plaques and thromboembolism. In atherosclerotic formations, a plaque develops under a fibrous cap. When the fibrous cap is degraded by metalloproteinases released from macrophages or by intravascular shear force from blood flow, subendothelial thrombogenic material (extracellular matrix
) is exposed to circulating platelets and thrombus formation occurs on the vessel wall occluding
blood flow. Occasionally, the plaque may rupture forming an embolus
that travels with the blood flow downstream where the vessel narrows and eventually clogs the vessel lumen.
Infarctions can also involve mechanical blockage of the blood supply, such as when part of the gut or testicles hernia
tes or becomes involved in a volvulus
.
present:
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
, infarction refers to tissue death (necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
) that is caused by a local lack of oxygen due to obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct.
Causes
The supplying arteryArtery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
may be blocked by an obstruction (e.g. an arterial embolus, thrombus
Thrombus
A thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
, or atherosclerotic plaque), may be mechanically compressed (e.g. tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
, volvulus
Volvulus
A volvulus is a bowel obstruction with a loop of bowel whose nose has abnormally twisted on itself.-Types:* Volvulus Neonatorum.* Volvulus Small Intestine.* Volvulus Caecum.* Volvulus Sigmoid Colon .* Gastric volvulus....
, or hernia
Hernia
A hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm....
), ruptured by trauma (e.g. atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
or vasculitides), or vasoconstricted (e.g. cocaine vasoconstriction leading to myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
).
Hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
and atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
are risk factors for both atherosclerotic plaques and thromboembolism. In atherosclerotic formations, a plaque develops under a fibrous cap. When the fibrous cap is degraded by metalloproteinases released from macrophages or by intravascular shear force from blood flow, subendothelial thrombogenic material (extracellular matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
) is exposed to circulating platelets and thrombus formation occurs on the vessel wall occluding
Vascular occlusion
Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
blood flow. Occasionally, the plaque may rupture forming an embolus
Embolism
In medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
that travels with the blood flow downstream where the vessel narrows and eventually clogs the vessel lumen.
Infarctions can also involve mechanical blockage of the blood supply, such as when part of the gut or testicles hernia
Hernia
A hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm....
tes or becomes involved in a volvulus
Volvulus
A volvulus is a bowel obstruction with a loop of bowel whose nose has abnormally twisted on itself.-Types:* Volvulus Neonatorum.* Volvulus Small Intestine.* Volvulus Caecum.* Volvulus Sigmoid Colon .* Gastric volvulus....
.
By histopathology
Infarctions are divided into 2 types according to the amount of bloodBlood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
present:
- White infarctions (anemic infarctAnemic infarctAnemic infarcts are white or pale infarcts caused by arterial occlusions, and are usually seen in the heart, kidney and spleen. These are referred to as "white" because of the lack of hemorrhaging and limited red blood cells accumulation,...
s) affect solid organs such as the spleenSpleenThe spleen is an organ found in virtually all vertebrate animals with important roles in regard to red blood cells and the immune system. In humans, it is located in the left upper quadrant of the abdomen. It removes old red blood cells and holds a reserve of blood in case of hemorrhagic shock...
and kidneys wherein the solidity of the tissueTissue (biology)Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
substantially limits the amount of nutrients (bloodBloodBlood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
/oxygenOxygenOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
/glucoseGlucoseGlucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
/fuelFuelFuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
) that can flow into the areaAreaArea is a quantity that expresses the extent of a two-dimensional surface or shape in the plane. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat...
of ischemic necrosisNecrosisNecrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
. Similar occlusionVascular occlusionVascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
to blood flowBlood flowBlood flow is the continuous running of blood in the cardiovascular system.The human body is made up of several processes all carrying out various functions. We have the gastrointestinal system which aids the digestion and the absorption of food...
and consequent necrosisNecrosisNecrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
can occur as a result of severe vasoconstrictionVasoconstrictionVasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries, small arterioles and veins. The process is the opposite of vasodilation, the widening of blood vessels. The process is particularly important in...
as illustrated in severe Raynaud's phenomenonRaynaud's phenomenonIn medicine, Raynaud's phenomenon is a vasospastic disorder causing discoloration of the fingers, toes, and occasionally other areas. This condition can also cause nails to become brittle with longitudinal ridges. Named for French physician Maurice Raynaud , the phenomenon is believed to be the...
that can lead to irreversible gangreneGangreneGangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies . This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood...
. - Red infarctions (hemorrhagic infarctHemorrhagic infarctHemorrhagic infarcts are infarcts commonly caused by occlusion of veins, with red blood cells entering the area of the infarct, or an artery occlusion of an organ with collaterals or dual circulation. This is commonly seen in brain, lungs, liver and the GI tract, areas referred to as having "loose...
s), generally affect the lungLungThe lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s or other loose organs (testis, ovaryOvaryThe ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
, small intestines). The occlusionVascular occlusionVascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
consists more of red blood cellRed blood cellRed blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s and fibrinFibrinFibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....
strands. Characteristics of red infarcts include: occlusion of a veinVeinIn the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
; loose tissues that allow bloodBloodBlood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
to collect in the infarcted zone; tissues with a dual circulatory systemCirculatory systemThe circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
(lung, small intestines); tissues previously congested from sluggish venous outflow; and reperfusion (injuryInjury-By cause:*Traumatic injury, a body wound or shock produced by sudden physical injury, as from violence or accident*Other injuries from external physical causes, such as radiation injury, burn injury or frostbite*Injury from infection...
) of previously ischemic tissue that is associated with reperfusion-related diseases such as - Myocardial infarctionMyocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
, strokeStrokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
(cerebral infarctionCerebral infarctionA cerebral infarction is the ischemic kind of stroke due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid...
), shock-resuscitation, replantation surgerySurgerySurgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...
, frostbiteFrostbiteFrostbite is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas...
, burnBurnA burn is an injury to flesh caused by heat, electricity, chemicals, light, radiation, or friction.Burn may also refer to:*Combustion*Burn , type of watercourses so named in Scotland and north-eastern England...
s and organ transplantOrgan transplantOrgan transplantation is the moving of an organ from one body to another or from a donor site on the patient's own body, for the purpose of replacing the recipient's damaged or absent organ. The emerging field of regenerative medicine is allowing scientists and engineers to create organs to be...
ation.
By localization
- Heart: Myocardial infarctionMyocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
(MI), commonly known as a heart attack, is an infarction of the heart, causing some heart cells to die. This is most commonly due to occlusion (blockage) of a coronary artery following the rupture of a vulnerable atherosclerotic plaqueVulnerable plaqueA vulnerable plaque is a kind of atheromatous plaque – a collection of white blood cells and lipids in the wall of an artery - that is particularly unstable and prone to produce sudden major problems, such as a heart attack or stroke.In many cases, a vulnerable plaque has a thin fibrous cap and a...
, which is an unstable collection of lipids (fatty acids) and white blood cellWhite blood cellWhite blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
s (especially macrophageMacrophageMacrophages are cells produced by the differentiation of monocytes in tissues. Human macrophages are about in diameter. Monocytes and macrophages are phagocytes. Macrophages function in both non-specific defense as well as help initiate specific defense mechanisms of vertebrate animals...
s) in the wall of an arteryArteryArteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
. The resulting ischemiaIschemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
(restriction in blood supply) and oxygen shortageHypoxia (medical)Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
, if left untreated for a sufficient period of time, can cause damage or death of heart muscle tissue (myocardium).
- Brain: Cerebral infarctionCerebral infarctionA cerebral infarction is the ischemic kind of stroke due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid...
is the ischemicIschemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
kind of strokeStrokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid hemorrhageSubarachnoid hemorrhageA subarachnoid hemorrhage , or subarachnoid haemorrhage in British English, is bleeding into the subarachnoid space—the area between the arachnoid membrane and the pia mater surrounding the brain...
. Cerebral infarctions vary in their severity with one third of the cases resulting in death.
- Spleen: Splenic infarctionSplenic infarctionIn medicine, splenic infarction is a condition in which oxygen supply to the spleen is interrupted, leading to partial or complete infarction in the organ....
occurs when the splenic arterySplenic arteryIn anatomy, the splenic artery is the blood vessel that supplies oxygenated blood to the spleen. It branches from the celiac artery, and follows a course superior to the pancreas.-Branches:...
or one of its branches are occluded, for example by a blood clot. Although it can occur asymptomaticAsymptomaticIn medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical...
ally, the typical symptom is severe painAbdominal painAbdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
in the left upper quadrant of the abdomenLeft upper quadrant (abdomen)thumb|right|A Graphic showing Contents of Left upper quadrantThe Left upper quadrant of the human abdomen, often abbreviated as LUQ, is used to refer to a portion of the abdomen that allows doctors to localise pain and tenderness, scars, lumps and other items of interest...
, sometimes radiating to the left shoulder. Fever and chills develop in some cases. It has to be differentiated from other causes of acute abdomenAcute abdomenThe term acute abdomen refers to a sudden, severe abdominal pain of unclear etiology that is less than 24 hours in duration. It is in many cases a medical emergency, requiring urgent and specific diagnosis...
.
- Limb: Limb infarctionLimb infarctionA limb infarction is an area of tissue death of an arm or leg. It may cause skeletal muscle infarction, avascular necrosis of bones, or necrosis of a part of or an entire limb.-Affected tissues:...
is an infarction of an armArmIn human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...
or legLegŁęg may refer to the following places in Poland:*A former name for the town of Ełk *Part of the Czyżyny district of Kraków*Łęg, Pleszew County in Greater Poland Voivodeship...
. Causes include arterial embolismArterial embolismArterial embolism is a sudden interruption of blood flow to an organ or body part due to an embolus adhering to the wall of an artery and blocks the flow of blood, the major type of embolus being a blood clot...
s and skeletal muscle infarction as a rare complication of long standing, poorly controlled diabetes mellitusDiabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
. A major presentation is painful thigh or leg swelling.
- Bone: Infarction of boneBoneBones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
results in avascular necrosisAvascular necrosisAvascular necrosis is a disease where there is cellular death of bone components due to interruption of the blood supply. Without blood, the bone tissue dies and the bone collapses...
. Without blood, the bone tissue dies and the bone collapses. If avascular necrosis involves the bones of a jointJointA joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
, it often leads to destruction of the joint articular surfaces (see osteochondritis dissecansOsteochondritis dissecansOsteochondritis dissecans , often abbreviated to OCD or OD, is a joint disorder in which cracks form in the articular cartilage and the underlying subchondral bone. OCD is caused by blood deprivation in the subchondral bone. This loss of blood flow causes the subchondral bone to die in a process...
).
- Testicle: an infarction of a testicleTesticleThe testicle is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system...
may be caused by testicular torsionTesticular torsionTesticular torsion is when the spermatic cord to a testicle twists, cutting off the blood supply. The most common symptom is acute testicular pain and the most common underlying cause is a congenital malformation known as a "bell-clapper deformity". The diagnosis is often made clinically but if it...
.
Associated diseases
Diseases commonly associated with infarctions include:- Peripheral artery occlusive diseasePeripheral artery occlusive diseasePeripheral vascular disease , commonly referred to as peripheral arterial disease or peripheral artery occlusive disease , refers to the obstruction of large arteries not within the coronary, aortic arch vasculature, or brain. PVD can result from atherosclerosis, inflammatory processes leading to...
(the most severe form of which is gangreneGangreneGangrene is a serious and potentially life-threatening condition that arises when a considerable mass of body tissue dies . This may occur after an injury or infection, or in people suffering from any chronic health problem affecting blood circulation. The primary cause of gangrene is reduced blood...
) - Antiphospholipid syndromeAntiphospholipid syndromeAntiphospholipid syndrome or antiphospholipid antibody syndrome , often also Hughes syndrome, is an autoimmune, hypercoagulable state caused by antibodies against cell-membrane phospholipids that provokes blood clots in both arteries and veins as well as pregnancy-related complications such as...
- SepsisSepsisSepsis is a potentially deadly medical condition that is characterized by a whole-body inflammatory state and the presence of a known or suspected infection. The body may develop this inflammatory response by the immune system to microbes in the blood, urine, lungs, skin, or other tissues...
- Giant-cell arteritis (GCA)
- HerniaHerniaA hernia is the protrusion of an organ or the fascia of an organ through the wall of the cavity that normally contains it. A hiatal hernia occurs when the stomach protrudes into the mediastinum through the esophageal opening in the diaphragm....
- VolvulusVolvulusA volvulus is a bowel obstruction with a loop of bowel whose nose has abnormally twisted on itself.-Types:* Volvulus Neonatorum.* Volvulus Small Intestine.* Volvulus Caecum.* Volvulus Sigmoid Colon .* Gastric volvulus....