A circulatory anastomosis is a connection (an

anastomosis An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal (su ...

) between two

blood vessels Blood vessels are the tubular structures of a circulatory system that transport blood throughout many animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the tissues of a body. They also take waste an ...

, such as between

arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

(arterio-arterial anastomosis), between

vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...

s (veno-venous anastomosis) or between an artery and a vein (arterio-venous anastomosis). Anastomoses between arteries and between veins result in a multitude of arteries and veins, respectively, serving the same volume of tissue. Such anastomoses occur normally in the body in the

circulatory system In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of the heart ...

, serving as back-up routes in a

collateral circulation Collateral circulation is the alternate Circulatory system, circulation around a blocked blood vessel, artery or vein via another path, such as nearby minor vessels. It may occur via preexisting vascular redundancy (analogous to redundancy (engi ...

that allow blood to flow if one link is blocked or otherwise compromised, but may also occur pathologically.

Physiologic

Arterio-arterial anastomoses include actual (e.g., palmar and plantar arches) and potential varieties (e.g., coronary arteries and cortical branch of cerebral arteries). There are many examples of normal arterio-arterial anastomoses in the body. Clinically important examples include: *

Circle of Willis The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...

(in the brain) * Coronary: anterior interventricular artery and

posterior interventricular artery In the coronary circulation, the posterior descending artery (PDA), also called the posterior interventricular artery (PIV, PIA, or PIVA), is an artery running in the posterior interventricular sulcus to the apex of the heart where it meets with ...

of the heart * Scapular anastomosis (for the subclavian vessels) * Joint

anastomoses An anastomosis (, : anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf#Veins, leaf veins, or streams. Such a connection may be ...

: Almost all joints receive anastomotic blood supply from more than one source. ** Shoulder (and circumflex humeral) ** Elbow (see blood supply of elbow) ** Hip (and circumflex iliac; see also cruciate anastomosis) ** Knee (and genicular arteries; see also patellar network) ** Ankle * Abdominal anastomoses ** Marginal artery of the colon * Pelvic anastomoses * Hand - palmar arches:

superficial palmar arch The superficial palmar arch is formed predominantly by the ulnar artery, with a contribution from the superficial palmar branch of the radial artery. However, in some individuals the contribution from the radial artery might be absent, and instea ...

and

deep palmar arch The deep palmar arch (deep volar arch) is an arterial network found in the palm. It is usually primarily formed from the terminal part of the radial artery. The ulnar artery also contributes through an anastomosis. This is in contrast to the super ...

* Foot -

plantar Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

arch

Coronary

Surgical intervention

Coronary anastomoses are a clinically vital subject: the coronary anastomosis is the blood supply to the heart. The coronary arteries are vulnerable to

arteriosclerosis Arteriosclerosis, literally meaning "hardening of the arteries", is an umbrella term for a vascular disorder characterized by abnormal thickening, hardening, and loss of elasticity of the walls of arteries; this process gradually restricts th ...

and other effects. Inadequate supply to the heart will lead to chest pains (

angina Angina, also known as angina pectoris, is chest pain or pressure, usually caused by insufficient blood flow to the heart muscle (myocardium). It is most commonly a symptom of coronary artery disease. Angina is typically the result of parti ...

) or a heart attack (

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...

). These can be ameliorated by surgical intervention to create a bypass using the anastomosis technique. Creation of an end-to-end anastomosis is a basic microsurgical skill that is taught to surgical residents and fellows. Akelina Y. Microsurgical technique for 1mm vessel end to end anastomosis. J Med Ins. 2014;2014(2). doi:https://doi.org/10.24296/jomi/2

Naturally occurring

Coronary anastomoses are anatomically present though functionally obsolete. There was some suggestion that they may be helpful if a problem develops slowly over time (this will need to be verified) but in the case of the pathogenesis of CHD they do not provide a sufficient

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

flow to prevent

infarction Infarction is tissue death (necrosis) due to Ischemia, inadequate blood supply to the affected area. It may be caused by Thrombosis, artery blockages, rupture, mechanical compression, or vasoconstriction. The resulting lesion is referred to as a ...

. There are anastomoses between the

Circumflex The circumflex () is a diacritic in the Latin and Greek scripts that is also used in the written forms of many languages and in various romanization and transcription schemes. It received its English name from "bent around"a translation of ...

and right coronary arteries and between the anterior and posterior inter-ventricular arteries. In the normal heart these anastomoses are non-functional.

Arterio-venous

Superficial arterio-venous anastomoses open when the body reaches a high temperature, and enable the body to cool itself. As warm arterial blood passes close to the surface it will decrease in temperature. This occurs together with

sweating Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distributed over much of the ...

Pathologic

Pathological Pathology is the study of disease. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in the context of modern medical treatme ...

circulatory anastomoses result from trauma or disease and may involve

s, or

. These are usually referred to as

fistula In anatomy, a fistula (: fistulas or fistulae ; from Latin ''fistula'', "tube, pipe") is an abnormal connection (i.e. tube) joining two hollow spaces (technically, two epithelialized surfaces), such as blood vessels, intestines, or other h ...

s. In the cases of veins or arteries, traumatic fistulas usually occur between artery and vein.

Portacaval anastomosis A portacaval anastomosis or portocaval anastomosis is a specific type of circulatory anastomosis that occurs between the veins of the portal circulation and the vena cava, thus forming one of the principal types of portasystemic anastomosis or po ...

, by contrast, is a veno-venous anastomosis between a vein of the

portal circulation In the circulatory system of vertebrates, a portal venous system occurs when a capillary bed pools into another capillary bed through veins, without first going through the heart. Both capillary beds and the blood vessels that connect them are ...

and a vein of the

systemic circulation In vertebrates, the circulatory system is a organ system, system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. It includes the cardiovascular system, or vascular system, that consists of ...

, which allows blood to bypass the liver in patients with

portal hypertension Portal hypertension is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5� ...

, often resulting in

hemorrhoids Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''he ...

esophageal varices Esophageal varices are extremely Vasodilation, dilated sub-mucosal veins in the lower third of the esophagus. They are most often a consequence of portal hypertension, commonly due to cirrhosis. People with esophageal varices have a strong tendenc ...

, or

caput medusae Caput medusae is the appearance of distended and engorged superficial epigastric veins, which are seen radiating from the umbilicus across the abdomen. The name ''caput medusae'' (Latin for "head of Medusa") originates from the apparent simil ...

. Circulatory anastomoses between monochorionic twins may result in

twin-to-twin transfusion syndrome Twin-to-twin transfusion syndrome (TTTS), also known as feto-fetal transfusion syndrome (FFTS), twin oligohydramnios-polyhydramnios sequence (TOPS) and stuck twin syndrome, is a complication of monochorionic multiple pregnancies (the most commo ...

References

{{Arteries and veins Angiology pl:Anastomoza (medycyna)