medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, a shunt is a hole or a small passage that moves, or allows movement of,

fluid In physics, a fluid is a liquid, gas, or other material that may continuously motion, move and Deformation (physics), deform (''flow'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are M ...

from one part of the

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anim ...

to another. The term may describe either

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

or acquired shunts; acquired shunts (sometimes referred to as

iatrogenic Iatrogenesis is the causation of a disease, a harmful complication, or other ill effect by any medical activity, including diagnosis, intervention, error, or negligence." Iatrogenic", ''Merriam-Webster.com'', Merriam-Webster, Inc., accessed 27 ...

shunts) may be either biological or mechanical. __TOC__

Types

Cardiac shunt In cardiology, a cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-s ...

s may be described as right-to-left, left-to-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic. *

Cerebral shunt A cerebral shunt is a device permanently implanted inside the head and body to drain excess fluid away from the brain. They are commonly used to treat hydrocephalus, the swelling of the brain due to excess buildup of cerebrospinal fluid (CSF). If ...

: In cases of

hydrocephalus Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the brain, which can cause pressure to increase in the skull. Symptoms may vary according to age. Headaches and double vision are common. Elderly adults with n ...

and other conditions that cause chronic increased

intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and at rest, is normally 7–15 mmHg for a supine adu ...

, a

one-way valve A check valve, non-return valve, reflux valve, retention valve, foot valve, or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. Check valves are two-port valves, meaning they have tw ...

is used to drain excess

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...

from the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

and carry it to other parts of the body. This valve usually sits outside the

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

but beneath the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

, somewhere behind the

ear In vertebrates, an ear is the organ that enables hearing and (in mammals) body balance using the vestibular system. In humans, the ear is described as having three parts: the outer ear, the middle ear and the inner ear. The outer ear co ...

. Cerebral shunts that drain fluid to the

peritoneal cavity The peritoneal cavity is a potential space located between the two layers of the peritoneum—the parietal peritoneum, the serous membrane that lines the abdominal wall, and visceral peritoneum, which surrounds the internal organs. While situated ...

(located in the upper abdomen) are called ''ventriculoperitoneal'' (''VP'') shunts. * Lumbar-peritoneal shunt (a.k.a. ''lumboperitoneal'', ''LP''): In cases of chronic increased

such as

idiopathic intracranial hypertension Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri and benign intracranial hypertension, is a condition characterized by increased intracranial pressure (pressure around the brain) without a detectable cause. The m ...

and

, a tube or shunt with or without a

is used to drain the excess

from the

and transport it to the peritoneal cavity. Unlike the ventriculoperitoneal shunt, however, a lumbar-peritoneal shunt is usually inserted in between two of the vertebrae in the lumbar and punctures the cerebrospinal fluid sack or lumbar subarachnoid space, it then runs beneath the

to the peritoneal cavity, where it is eventually drained away by the normal bodily fluid drainage system. * A

Peritoneovenous shunt A peritoneovenous shunt is a shunt which drains peritoneal fluid from the peritoneum into a large vein, usually the internal jugular vein. It is sometimes used in patients with refractory ascites. It is a long tube with a one-way valve running ...

: (also called Denver shunt) is a shunt which drains

peritoneal fluid Peritoneal fluid is a serous fluid made by the peritoneum in the abdominal cavity which lubricates the surface of tissue that lines the abdominal wall and pelvic cavity. It covers most of the organs in the abdomen. An increased volume of peritone ...

from the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesotheli ...

into

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, usually the

internal jugular vein The internal jugular vein is a paired jugular vein that collects blood from the brain and the superficial parts of the face and neck. This vein runs in the carotid sheath with the common carotid artery and vagus nerve. It begins in the posteri ...

or the

superior vena cava The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vei ...

. It is sometimes used in patients with refractory

ascites Ascites (; , meaning "bag" or "sac") is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdo ...

. It is a long tube with a non-return valve running subcutaneously from the peritoneum to the internal jugular vein in the neck, which allows ascitic fluid to pass directly into the systemic circulation. Possible compilations include bleeding from

varices A varix (: varices) is an abnormally dilated blood vessel with a tortuous course. Varices usually occur in the venous system, but may also occur in arterial or lymphatic vessels. Examples of varices include: * Varicose veins, large tortuous veins ...

disseminated intravascular coagulation Disseminated intravascular coagulation (DIC) is a condition in which blood clots form throughout the body, blocking Microvessel, small blood vessels. Symptoms may include chest pain, shortness of breath, leg pain, problems speaking, or problems ...

, infection, superior vena caval thrombosis and

pulmonary edema Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

. *

Pulmonary shunt A pulmonary shunt is the passage of deoxygenated blood from the right side of the heart to the left without participation in gas exchange in the pulmonary capillaries. It is a pathological condition that results when the alveoli of parts of the l ...

s exist when there is normal

perfusion Perfusion is the passage of fluid through the circulatory system or lymphatic system to an organ (anatomy), organ or a tissue (biology), tissue, usually referring to the delivery of blood to a capillary bed in tissue. Perfusion may also refer t ...

to an

alveolus Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * M ...

, but

ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Respirator, a ma ...

fails to supply the perfused region. * A

portosystemic shunt A portosystemic shunt or portasystemic shunt (medical subject heading term; PSS), also known as a liver shunt, is a bypass of the liver by the body's circulatory system. It can be either a congenital (present at birth) or acquired condition and occ ...

(PSS), also known as a liver shunt, is a bypass of the

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

by the body's

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 ...

. It can be either a congenital or acquired condition. Congenital PSS is an uncommon condition in dogs and cats, found mainly in small dog breeds such as

Miniature Schnauzer The Miniature Schnauzer is a dog breed, breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers may have been developed from the smallest specimens of the Standard Schnauzer, or c ...

s and

Yorkshire Terrier The Yorkshire Terrier, also known as a Yorkie, is a British breed of toy dog of terrier type. It is among the smallest of the terriers and indeed of all dog breeds, with a weight of no more than . It originated in the nineteenth century in the ...

s, and in cats such as

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

s, Himalayans, and mix breeds. Acquired PSS is also uncommon and is found in older dogs with liver disease causing

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� ...

, especially

cirrhosis Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, chronic liver failure or chronic hepatic failure and end-stage liver disease, is a chronic condition of the liver in which the normal functioning tissue, or parenchyma, is replaced ...

. * A

portacaval shunt A portacaval shunt, portocaval shunt, or portal-caval shunt is a surgical procedure where a connection (a shunt) is made between the portal vein and the inferior vena cava. Under normal circumstances, the portal vein drains blood from the abd ...

(portal caval shunt) is a treatment for high blood pressure in the liver. * A

transjugular intrahepatic portosystemic shunt Transjugular intrahepatic portosystemic shunt (TIPS or TIPSS) is an artificial channel within the liver that establishes communication between the inflow portal vein and the outflow hepatic vein. It is used to treat portal hypertension (which is ...

(TIPS) is an artificial channel within the

that establishes communication between the inflow

portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approxima ...

and the outflow

hepatic vein In human anatomy, the hepatic veins are the veins that drain venous blood from the liver into the inferior vena cava (as opposed to the hepatic portal vein which conveys blood from the gastrointestinal organs to the liver). There are usually thre ...

. It is used to treat

. * VASP (Vesicoamniotic shunting procedure): Fetal lower urinary tract outflow obstruction prevents the unborn baby from passing urine. This can result in a reduction in the volume of

amniotic fluid The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products betwee ...

, and problems with the development of the baby's lungs and kidneys. A vesico–amniotic shunt is a tube that it is inserted into the unborn baby's bladder to drain the excess fluid into the surrounding space. IP overview: fetal vesico-amniotic shunt for bladder outflow obstruction (April 2006) Page 1 of 18, NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE, INTERVENTIONAL PROCEDURES PROGRAMME, Interventional procedure overview of fetal vesico-amniotic shunt for lower urinary tract outflow obstruction
/ref>

References

{{DEFAULTSORT:Shunt (Medical) Implants (medicine) Pediatric surgical procedures Vascular surgical procedures