Shunt (medical)

As shunt ( pronunciation: [ ʃʌnt ] ) is called in medicine a short circuit connection with fluid transfer between normally separate vessels or cavities. This can occur naturally be artificially created ( eg in the context of malformations such as arteriovenous malformations ) or as part of a medical procedure.

• 2.1 symptoms
• 2.2 shunt between large and small circulation
• 2.3 shunt operations on the heart

Embryonic shunts

During the embryonic and fetal period of the child, there are three shunts. The liver Hunt, who Aortenshunt and the court Hunt. These three shunts are in Embryonalkreislauf necessary because the child can not take care of himself by breathing oxygen. As long as the lungs are collapsed, the child is dependent on oxygen, which is provided by the placenta. The shunts close after birth. However, may be caused by Nichtverschließung different heart defects that can be remedied surgically.

Liver Hunt

The liver Hunt is characterized in that the umbilical vein ( umbilical vein ) bypasses the liver circulation, in which it is connecting through the ductus venosus (also ductus Arantii called ) with the inferior vena cava ( inferior vena cava ), and thus goes directly to the heart. This has the consequence that in the children's hearts mixed blood, so oxygen-poor ( from the inferior vena cava ) and oxygen-rich ( umbilical vein ), arrives. The oxygen and nutrient content of the blood of the umbilical vein, however, due to the liver Hunts far less degree than would be the case without the shunt, so that the oxygen content of the mixed blood for the child's care is still sufficient.

Atrial Hunt

During heart development of the cardiac tube is divided in the middle cranial at the Bluteinstrombahnen. This division by tissue called septa. First, a septum primum is created that shares the common atrium into right and left. In this division, however, remains an atrial foramen primum ( " first hole "). This hole is near the endocardial cushions, which lies medial to the heart. This hole closes and a new hole. The foramen secundum or patent foramen ovale. It is important that the foramen ovale in the septum is formed primum. The foramen ovale is closed by a curtain, the septum secundum. This septum is formed on the right side of the heart, that is part of the right atrium. This guarantees the septum blood flow from the right atrium into the left, with a blood exchange from the left atrium into the right is prevented. The foramen ovale thus forms the atrial Hunt to inferior to lead the mixed blood from the vena cava into the left atrium, so that the left heart can supply the body with oxygenated blood.

Aortenshunt

Since the lungs are not yet operational and collapses the lung is bypassed through the ductus arteriosus (or ductus arteriosus ). Starting from the pulmonary trunk, the ductus arteriosus goes to the aorta. However, the ductus arteriosus carries deoxygenated blood from the right ventricle to the aorta only when the common carotid artery and subclavian artery were disposed of. Thus, the brain and the arms get the oxygen- richest blood, the rest of the body is supplied with sauerstoffärmerem blood.

Haemodynamic shunts

Symptoms

• A shunt may change the pressure conditions within the blood vessels significantly. For example, a shunt limit the attainable blood pressure as part of a ventricular septal defect.

• It can also be reduced by mixing with a shunt, the oxygen saturation of the blood. Since the partial pressure ratio of saturation is not linear, but sigmoid, it may have a deficiency of the organism.

Shunt between large and small circulation

Clinically significant are those short connections between the outgoing of the right heart pulmonary circulation, and the outgoing from the left side of the heart systemic circulation in congenital heart disease ( atrial or ventricular septal defect ) or other developmental disabilities, such as the ductus arteriosus or patent foramen ovale ( PFO ). According to the higher pressure in the systemic circulation of the left heart first, there is always a left- to-right shunt; is it the same to a structural change of the permanent load of the right heart, it can lead to shunt reversal with subsequent right-left shunt. This process is called Eisenmenger reaction.

Congenital arteriovenous shunts of the peripheral vessels is called AV malformation. This is a congenital vascular connection between an artery and a vein with no intervening capillary bed. Iatrogenic can also in the context of arterial puncture through a vein accidentally through, for example, in the context of a cardiac catheterization, arise fistulae ( AV fistula ).

Shunt operations on the heart

In certain congenital heart defects, an artificial shunt between arterial and venous circulation is applied to improve the oxygenation of the patient. The classic shunt is the Blalock Taussig anastomosis. In many cases, this shunt is removed as part of a corrective or palliative surgery of further heart failure.

Dialysis shunts

In dialysis patients, a shunt (or arteriovenous fistula ) is artificially created in order to have a large-volume vessel available, with which you can perform hemodialysis. This method was developed in 1960 by Belding Scribner.

The preferred site for a dialysis fistulas, the connection between the radial artery and the cephalic vein in the forearm. This shunt is named after the Erstbeschreibern also Cimino -Brescia shunt. More possibilities for a dialysis fistulas in the upper arm, the compounds of the mobilized and relocated under the skin basilic vein to the brachial artery (so-called Basilica shunt) or between the cephalic vein and brachial artery (so-called cephalic shunt).

Dialysis shunts are vital for patients with severe renal failure (renal failure).

Ventriculo - peritoneal shunt

A so-called VP shunt is in neurosurgery a permanent drainage of cerebrospinal fluid in hydrocephalus, which is applied operationally. Here, a hose from the skull forth is beneath the skin down out front of the chest wall to the peritoneal cavity ( peritoneal cavity ) through the neck. There VP shunt having a valve adjustable from outside to adjust the outflow of the requirements ( See also intracranial pressure ). A further leading article on Cerebralshunts devoted to this subject in detail.