Understanding vascular malformations

Vascular malformations are abnormalities of blood and lymphatic vessels that are present from birth. They can occur anywhere in the body. In this article, Dr Lakshmi Ratnam, a consultant diagnostic and interventional radiologist, explains the types of vascular malformations, how they are diagnosed, and how they are treated. 

What are vascular malformations? 

Vascular malformations can affect veins, arteries, and lymphatic channels. They are conditions that are congenital (present from birth), forming during the development of the blood vessels in the womb. Some vascular malformations are associated with skin changes, and these are usually apparent from birth. Others may only become obvious later in life. Some vascular malformations are associated with known genetic abnormalities. 

They can develop anywhere in the body, and may appear as areas of discolouration and swelling. They may be accompanied by other symptoms such as pain, issues with function and mobility (for example, difficulty swallowing or walking, muscle weakness and numbness), headaches, infections, and excessive bleeding from lesions. The symptoms will vary depending on the size, type and location of the malformation. 

Vascular malformations can remain stable in size and appearance, become larger and cause more symptoms as time passes, or regress spontaneously without any treatment.

Vascular malformations can be divided into: 

• Slow flow vascular malformations – include venous, lymphatic, mixed veno-lymphatic and capillary malformations 
• Fast flow vascular malformations – include AVMs (arteriovenous malformations) 

How are vascular malformations diagnosed? 

Vascular malformations near the surface of the skin often have a visual sign of their presence (skin changes usually present from birth), but others that are rooted deeper in the tissues or in a part of the body that is harder to see and may not be so obvious. 

When seeking a diagnosis for a vascular malformations, imaging techniques that provide insight into the blood flow are often utilised, such as ultrasounds, MRIs, CT scans, and angiograms. A vascular ultrasound or Doppler ultrasound, where ultrasonic waves are emitted and echoed back to a probe and the data is computed to show the structure of the blood vessels and the speed of blood flow is often the first line of imaging. MRI scans are useful to outline the extent of a vascular malformation and its relationships to surrounding structures. It can also be useful to plan treatment. An angiogram is an invasive test where a catheter is inserted into the blood vessels and a dye injected to outline blood flow. This technique is reserved for the assessment and treatment of fast flow vascular malformations. 

How are vascular malformations treated? 

To treat vascular malformations, doctors prioritise minimising the impact of symptoms and preventing complications in the future. Those that aren’t considered problematic can be left alone, with monitoring over time to see if there has been progression. 

Approaches to treatment vary depending on the type of vascular malformation. The first step in a treatment pathway is to have a specialist assessment, which includes imaging and a clinical review. This is important so you gain an understanding of the type of vascular malformation and to ensure that the diagnosis is correct. If there is any doubt over the diagnosis, your doctor may recommend that you have a biopsy. This involves removing a very small part of the tissue to have it looked at by pathologists under a microscope to confirm the diagnosis.

Treatment strategies include the following.

1. Conservative management – it is possible that no treatment is required. However, the use of compression garments may be recommended.  
2. Percutaneous sclerotherapy – this is the first line of treatment for most slow flow vascular malformations. Several treatment sessions are usually required and these are usually carried out under local anaesthetic. The treatment involves the injection of a medication known as a sclerosing agent into the vascular malformation.
3. Electrosclerotherapy – this involves the application of an electric current to the vascular malformation after injection of a sclerosant. The electroporation produced increases the effect of the drug. This is more suited to larger vascular malformations, or those resistant to treatment with conventional sclerotherapy, and is performed under general anaesthesia.
4. Catheter embolisation – this treatment is used for fast flow vascular malformations. The procedure is performed to block the abnormal communication between arteries and veins.
5. Surgery – this is more invasive but can be the best choice for certain types of malformations. 

The diagnosis and management of vascular malformations are a specialised area of medicine. It is important to understand the type of vascular malformation and to consider the best treatment option for an individual. This will vary depending on the type, location and symptoms experienced.