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Arteriovenous malformations are so-called "fast-flow" vascular malformations.
Normally, arteries and veins are connected by a network of small vessels known as the capillary bed. In AVMs, however, the arteries and veins are connected to each other at multiple points without the aid of this capillary bed, creating what are known as shunts. The arteries and veins involved are enlarged, and the flow in the veins is abnormally high.
In a child, an AVM looks like a slightly pulsating red spot. It is often mistaken for an infantile hemangioma (a very common benign childhood tumor) or a "false planar angioma", commonly known as a wine stain. AVMs become clinically more visible as their vascular flow increases. The skin becomes redder and small flutters can be palpated.
AVMs are congenital vascular anomalies, which means that they are present from birth, but will be more or less visible.
In the vast majority of cases, these malformations are not hereditary, i.e. the malformation affects only one individual in a family, and this individual will not transmit the malformation to his or her children. But in rare cases, they can be either hereditary and linked to a genetic mutation that can be passed on to offspring (Rasa 1 and EPHB4 mutations); or linked to sporadic non-hereditary somatic mutations (Map2k1, Kras, Braf...).
No food, medication or activity ingested during pregnancy is responsible for the development of arteriovenous malformations.
AVMs are the result of a defect in the formation of arteries, veins and capillaries during embryogenesis, at the beginning of embryonic life (1st trimester of pregnancy). At birth, they may not be visible, even if they are present.
They can appear much later, in childhood, adolescence or adulthood. Certain factors can cause them to evolve, notably hormonal factors in women (puberty, the contraceptive pill, especially estrogen, pregnancy, pre-menopause).
Arteriovenous malformations have an unpredictable evolution over time, and may increase in size or become more symptomatic after a hormonal change or trauma.
The following symptoms and complications are possible:
- Pain
- Change in skin color with increase in malformation volume
- Ulcerations
- Bleeding
- Exceptionally, a risk of heart failure due to increased blood flow in the AVM
Each AVM is an individual case, and so there is no standard procedure. This is where a multidisciplinary consultation is essential, in order to establish the most appropriate therapeutic attitude for the patient.
The various possible treatments are listed below, and may sometimes be combined:
- Lifelong clinical monitoring at least once a year, with regular Doppler ultrasound examinations
- Wearing compression garments to improve venous drainage
- Embolization (in interventional radiology)
- Surgical resection: removal of part or all of the AVM
- Drug treatments may also be proposed (beta-blockers, targeted therapies).
In all cases, it is important to consult a physician as soon as possible if there is a clinical worsening of the AVM, or a worsening of the general condition (shortness of breath, intense fatigue).
Further information is available on the PNDS :
https://www.has-sante.fr/upload/docs/application/pdf/2021-11/pnds_mav_superficielle_-_nov2021.pdf
