Arteriovenous Malformations


The term vascular malformation is a general term and includes any malformation (i.e. congenital anomaly) involving vessels. A vascular malformation may be located anywhere in the body.

There are venous malformations (only veins), lymphatic malformations (only lymph vessels), venolymphatic malformations (veins and lymph vessels) and arteriovenous malformations (arteries directly connected to veins without capillaries in between).

Although all vascular malformations are present at birth, they become apparent at different ages. We know that they occur during embryonic development, but we do not know what causes them. There is currently scientific work done with regard to the genetics of vascular malformations. Hereditary haemorrhagic telangiectasia is inherited as an autosomal dominant trait.

Venous malformations – They may cause pain locally. Venous and lymphatic malformations may cause a lump under the skin with a birthmark on the overlying skin. Venous and lymphatic malformations may be associated with Klippel-Trenaunay syndrome.

Arteriovenous malformations – They may cause pain. If there have a very high blood flow, they may be stressful on the heart causing cardiac failure. Depending on their location they may cause bleeding (in organs like the bowels, the uterus and the bladder). They may also cause ischaemia, i.e. significant reduction of blood flow to more distal tissues; for example, an arteriovenous malformation at the level of the ankle may cause ischaemic rest pain in the forefoot because of shunt of blood from arteries to veins. When they occur in the head and neck, they may cause severe tinnitus

haemangioma is not a vascular malformation, but a benign tumour which may be present at birth.

Haemangiomata may also present as birthmarks, however, they grow rapidly early in life and at a second stage they show spantaneous involution (although this process may last for several years), as opposed to the vascular malformations which grow proportionally to the child’s growth. Vascular malformations do not involute spontaneously.

Physical examination is often helpful to diagnose these lesions. To study deeper tissues or to demonstrate arteriovenous shunts, magnetic resonance imaging (MRI) or digital subtractive angiography may be used.

Management depends upon the type of vascular malformation.

In certain cases, when the lesion is relatively localised, surgical excision may be radical and, therefore, very effective. However, it is generally difficult to completely remove a rather extensive vascular malformation, which will return if not removed completely.

Some vascular malformations are complex lesions (extensive, affecting several tissues or vital organs etc) and may require treatment by a multidisciplinary group of physicians apart from the vascular surgeon, consisting of interventional radiologist, plastic surgeon, orthopaedic surgeon, general surgeon, ENT or thoracic surgeon.

If a feeding artery of a lesion is recognised (the case with an arteriovenous malformation or a haemangioma), embolisation can be performed with suitable material (like absolute alcohol or “glue”, i.e. N-butyl-2-cyanoacrylate), which is injected via an angiography catheter until the lesion is fully devascularised and no longer has blood flowing through it. In general, embolisation is an effective method, although it may require a series of treatments. Some venous and lymphatic malformations may be treated with direct puncture and embolisation (usually with absolute alcohol or 3% sodium tetradecyl sulphate, STD).

All vascular malformations require long-term surveillance – even following treatment – most importantly at puberty, pregnancy, menopause or after injury, because new symptoms may appear speeding up the need for interventional treatment.