Arteriovenous malformations (AVM) are congenital vascular malformations. They occurin particularin the area of the central nervous system and the facial skull. This results in a "short circuit" in the blood vessel system without an intervening capillary network. The operation of such vascular shunts is difficult and usually requires great expertise.
Here you will find further information as well as selected AVM specialists and centers.
Cerebral means "affecting the brain", and the medical term "arteriovenous malformation" can be translated and explained as follows:
Normally, blood rich in oxygen and nutrients flows from the left heart at high pressure (approx. 120-140mmHg) into all organs and tissues of the body. This is where the exchange of substances between blood and tissue cells takes place in the so-called "capillary bed". The capillaries are the smallest end branches of the arteries with a very thin wall through which substances can diffuse (pass through).
On the other side of the capillary bed, tiny venous branches (venules) collect the now oxygen- and nutrient-poor blood and transport it back to the right heart at a lower pressure (approx. 10-20 mmHg). Here it is supplied with oxygen via the lungs and nutrients via the liver before re-entering the above-mentioned circulation.
If arteriovenous malformations are present, the arterial blood enters the veins directly and at high pressure via the malformations (= short circuits) without carrying out the exchange of substances in the capillary bed.
Thetwo main problems of AV malformations result from the short-circuit connections described:
Approximately one in 1,000 newborns is born with an arteriovenous malformation.
In principle, any organ system can be affected by such a vascular short circuit. However, the anomaly occurs more frequently in the area of the brain or the facial skull.
In children under the age of 15, arteriovenous malformations are also the most common cause of cerebral hemorrhages (intracranial hemorrhages).
Arteriovenous malformations develop between the 4th and 8th week of pregnancy from the first primitive blood vessels. Primitive means that they are simple, even before differentiation into more complex vascular structures.
What exactly triggers the short circuits in the blood vessels is still unclear. It is possible that genetic predispositions or external influences during pregnancy promote arteriovenous malformations.
The actual arteriovenous malformation is also known in medicine as a nidus (literally translated as nest) . This is the core of the anomaly. Several, often dilated arteries supply blood to the nidus, which is then passed on to dilated veins.
The blood from the arteries is subject to a higher blood pressure. This usually leads to congestion and dilatation in the veins. Such vein dilatations can lead to venous aneurysms or stenoses (narrowing of blood vessels).
In an arteriovenous malformation, the capillary network between an artery and a vein is missing © rumruay | AdobeStock
These vascular changes eventually become visible along the arteriovenous malformation.
Vascular shunts (unnatural connections between vessels) such as arteriovenous malformations can remain asymptomatic for a lifetime.
In many patients, however, the first symptoms appear between the ages of 20 and 40, as the disease and the vascular dilatations continue to expand and become larger. Common typical symptoms include
In most patients, pulsating vascular noises are found in the area of the skull. They occur because the blood flows at a higher speed from the arteries into the short-circuited veins.
Normally, the capillary network in the organ area enables the exchange of substances and gases and slows down the blood. This capillary network is missing in arteriovenous malformation. As a result, the blood flows at high arterial pressure directly into a short-circuited vein. This short circuit between the artery and vein is also known in medicine as a shunt. These higher blood flow velocities through the shunt can be visualized using transcranial Doppler or colour duplex sonography.
The suspicion of arteriovenous shunts is then confirmed using
confirmed. These two diagnostic procedures allow specialists to determine the exact location of the arteriovenous malformation.
Computed tomography (CT) is not really important in the imaging of vascular short circuits. However, it is used in emergency diagnostics, e.g. in cases of loss of consciousness following cerebral hemorrhage.
Invasive angiography with contrast medium is of crucial diagnostic and therapeutic importance. In this procedure, a catheter is inserted into the groin and advanced into the brain, and after administering a contrast agent, the short-circuit connections can be precisely visualized. This examination is described as invasive, as the puncture interferes with the integrity of the body. It should therefore only be indicated in combination with therapeutic treatment.
The treatment of vascular shunts is often difficult and involves serious risks. For this reason, each case is discussed individually in an interdisciplinary decision-making committee at the specialist clinic.
Depending on the location of the arteriovenous malformation, surgery or radiotherapy may not be safe. In these cases, treatment is conservative with medication or avoidance of stressful situations: The aim here is to alleviate the symptoms, such as epilepsy with anti-epileptic drugs.
For operable arteriovenous malformations, there is minimally invasive therapy and open surgery:
The aim of every operation is to reduce the risk of bleeding and also the tendency of arteriovenous malformations to recur.
The treatment of arteriovenous malformations in the brain involves various medical disciplines, e.g. specialists from
Conservative therapy can be carried out at specialized centers and in specialist practices. Surgical procedures require treatment at a specialized clinic by specialists in neurosurgery and neuroradiology.
The risk of bleeding in particular is decisive for the prognosis of vascular shunts. Normally, this is around 2-3% per year. However, the mortality rate from bleeding is quite high at up to 10 %. In addition, neurological deficits persist in every third patient.
In addition, anyone who has had a first hemorrhage due to an arteriovenous malformation is around 25% likely to experience another bleeding event within the following years.
Without treatment, one in four affected patients will die from their arteriovenous malformation within 10 years.
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