Circulatory anastomosis
Encyclopedia
A circulatory anastomosis is a connection (an anastomosis
) between two blood vessels, such as between arteries (arterio-arterial anastomosis), between veins (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
, serving as backup routes for blood to flow if one link is blocked or otherwise compromised, but may also occur pathologically.
There are many examples of normal arteri-arterial anastomoses in the body. However clinically important examples include:
and other effects. Inadequate supply to the heart will lead to chest pains (angina) or a heart attack (myocardial infarction
).
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
flow to prevent infarction
.
There are anastomoses between the Circumflex and right coronary arteries and between the anterior and posterior inter-ventricular arteries. In the normal heart these anastomoses are non-functional.
anastomoses result from trauma or disease and may involve vein
s, arteries
, or intestines. These are usually referred to as fistula
s. In the cases of veins or arteries, traumatic fistulas usually occur between artery and vein. Traumatic intestinal fistulas usually occur between two loops of intestine (enetero-enteric fistula) or intestine and skin
(enterocutaneous fistula). Portacaval anastomosis
, by contrast, is a veno-venous anastomosis between a vein of the portal circulation and a vein of the systemic circulation
, which allows blood to bypass the liver in patients with portal hypertension
, often resulting in hemorrhoids, esophageal varices
, or caput medusae
.
Circulatory anastomoses between monochorionic twins
may result in twin-to-twin transfusion syndrome
.
Anastomosis
An anastomosis is the reconnection of two streams that previously branched out, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....
) between two blood vessels, such as between arteries (arterio-arterial anastomosis), between veins (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
Circulatory system
The circulatory system is an organ system that passes nutrients , gases, hormones, blood cells, etc...
, serving as backup routes for blood to flow if one link is blocked or otherwise compromised, but may also occur pathologically.
Physiologic
Arterio-arterial anastomoses include actual ones (eg. palmar arch, plantar arch) and potential ones (eg. coronary arteries and cortical branch of cerebral arteries).There are many examples of normal arteri-arterial anastomoses in the body. However clinically important examples include:
- Circle of WillisCircle of WillisThe Circle of Willis is a circle of arteries that supply blood to the brain...
(in the brain) - scapular anastomosisScapular anastomosisThe scapular anastomosis is a system connecting each subclavian artery and the corresponding axillary artery, forming an anastomosis around the scapula. It allows blood to flow past the joint regardless of the position of the arm...
(for the subclavianSubclavian arteryIn human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...
vessels) - joint anastomoses - clinically very important. Almost all joints receive anastomotic blood supply from more than one source. Examples include knee (and geniculate arteries), shoulder (and circumflex humeral), hip (and circumflex iliac) and ankle. See also patellar networkPatellar networkThe patellar network is an intricate network of vessels around and above the patella, and on the contiguous ends of the femur and tibia, forming a superficial and a deep plexus.* The superficial plexus is situated between the fascia and skin...
. - pelvic anastomoses
- abdominal anastomoses
- hand and foot anastomoses (which include the palmar and plantarPlantar archThe plantar arch is formed from:* deep plantar artery, from the dorsalis pedis - aka dorsal artery of the foot* lateral plantar arteryThe plantar arch supplies the underside, or sole, of the foot....
arches) - Coronary: anterior and posterior inter-ventricular arteries of the heart
Coronary
Coronary anastomoses are a clinically vital subject: the coronary anastomosis is the blood supply to the heart. The coronary arteries are vulnerable to arteriosclerosisArteriosclerosis
Arteriosclerosis refers to a stiffening of arteries.Arteriosclerosis is a general term describing any hardening of medium or large arteries It should not be confused with "arteriolosclerosis" or "atherosclerosis".Also known by the name "myoconditis" which is...
and other effects. Inadequate supply to the heart will lead to chest pains (angina) or a heart attack (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...
).
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
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....
flow to prevent infarction
Infarction
In medicine, infarction refers to tissue 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:...
.
There are anastomoses between the Circumflex and right coronary arteries and between the anterior and posterior inter-ventricular arteries. In the normal heart these anastomoses are non-functional.
Pathological
PathologicalPathology
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....
anastomoses result from trauma or disease and may involve vein
Vein
In 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...
s, arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
, or intestines. These are usually referred to as fistula
Fistula
In medicine, a fistula is an abnormal connection or passageway between two epithelium-lined organs or vessels that normally do not connect. It is generally a disease condition, but a fistula may be surgically created for therapeutic reasons.-Locations:Fistulas can develop in various parts of the...
s. In the cases of veins or arteries, traumatic fistulas usually occur between artery and vein. Traumatic intestinal fistulas usually occur between two loops of intestine (enetero-enteric fistula) or intestine and skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
(enterocutaneous fistula). Portacaval anastomosis
Portacaval anastomosis
A portacaval anastomosis is a specific type of anastomosis that occurs between the veins of portal circulation and those of systemic circulation....
, by contrast, is a veno-venous anastomosis between a vein of the portal circulation and a vein of the systemic circulation
Systemic circulation
Systemic circulation is the part of the cardiovascular system which carries oxygenated blood away from the heart to the body, and returns deoxygenated blood back to the heart. This physiologic theory of circulation was first described by William Harvey...
, which allows blood to bypass the liver in patients with portal hypertension
Portal hypertension
In medicine, portal hypertension is hypertension in the portal vein and its tributaries.It is often defined as a portal pressure gradient of 10 mmHg or greater.-Causes:Causes can be divided into prehepatic, intrahepatic, and posthepatic...
, often resulting in hemorrhoids, esophageal varices
Esophageal varices
In medicine , esophageal varices are extremely dilated sub-mucosal veins in the lower esophagus...
, or caput medusae
Caput medusae
Caput medusae is the appearance of distended and engorged paraumbilical veins, which are seen radiating from the umbilicus across the abdomen to join systemic veins...
.
Circulatory anastomoses between monochorionic twins
Monochorionic twins
Monochorionic twins are monozygotic twins that share the same placenta. If the placenta is shared by more than two twins , these are monochorionic multiples. Monochorionic twins occur in 0.3% of all pregnancies. 75% of monozygotic twin pregnancies are monochorionic; the remaining 25% are...
may result in twin-to-twin transfusion syndrome
Twin-to-twin transfusion syndrome
Twin-to-twin transfusion syndrome is a complication of disproportionate blood supply, resulting in high morbidity and mortality. It can affect monochorionic multiples, that is multiple pregnancies where two or more fetuses share a chorion and hence a single placenta...
.