This information will help to explain what venous malformations are and their treatment. If you have any questions please do not hesitate to contact the clinical nurse specialist team via the numbers at the end of this webpage.
What is an arteriovenous malformation (AVM)?
AVMs occur when blood flows directly from an artery into a vein instead of passing through a microscopic network of vessels called capillaries. AVMs are often present at birth. Common locations for AVMs are in the brain, neck, and spine, but they can also be found elsewhere on the body including internal organs such as the kidneys, intestines, and lungs. They can show rapid growth over a relatively short period of time during childhood or adulthood. However, at certain times, when the body’s hormone levels increase, such as in puberty and pregnancy, they can grow more quickly. Growth of an AVM can also be as a result of clotting, infection and trauma. They are one of the rare types of vascular malformation.
What is a vascular malformation?
Vascular malformation is a general terms used to describe an abnormal cluster of vessels. They can come in a number of forms.
- Venous malformations. These often have a slow flow of blood running through them.
- Arterio-venous malformations. These often have a higher flow of blood running through them.
- Lymphatic malformations. These contain a clear fluid rather than blood; lymphatic malformations tend to be very slow flow.
Sometimes there can be a combination of the above.
In this information booklet we will be looking at peripheral arteriovenous malformations (AVMs)
Are they harmful?
AVMs are benign. They are not a tumour or cancer, and whilst some people have extensive problems affecting several areas of their body, they cannot spread to other areas of the body.
Patients who have AVMs may experience the following symptoms:
- Swelling: This is often a soft lump that can appear on the affected part of the body; the swelling can increase and decrease at different times.
- Pain: This can be mild to severe depending on the size and location of the malformation
- Skin discolouration.
- Bleeding.
- Increased swelling and pain caused by clot formation in the malformation.
- Rarely ulceration.
How do we treat AVMs?
You will go through several steps to allow us to make the best decision regarding your care.
Back to topWhat does the treatment involve?
This depends on the type of malformation you have.
This information will be looking at peripheral arteriovenous malformations (AVMs) also known as high flow malformations. Normally, patients with an AVM are admitted onto a ward as they will need a general anaesthetic and often need close observation following their procedure.
On arrival to the ward you will be clerked in by the ward team. They will put you into a hospital gown, they may also insert a cannula (plastic tube) into your arm to administer drugs and fluids if needed. When we are ready to carry out the procedure we will call the ward to let them know. Once in Radiology Theatres the consultant interventional radiologist performing the procedure will confirm your consent to undergo the procedure and answer any further questions you may have.
Arteriovenous malformations (AVMs) or high flow malformations are treated somewhat differently to venous or lymphatic malformations. Due to their high flow nature it is preferable to embolise(block off) the arteries involved in the malformation. This is done by inserting a fine tube called a catheter into the vessels in the malformation. These vessels are then blocked using different agents as below.
Coils
- The coils we insert are like small springs, they are made of platinum or stainless steel and are designed to block blood vessels within the AVM
Onyx
- This agent forms a solid but spongy cast in the malformation. It is injected through a small catheter. It forms a permanent cast in the malformation, and reduces or blocks the flow through the AVM
Other treatment options
Absolute alcohol sclerotherapy
This agent is injected into the malformation, but instead of embolising the malformation it causes clots inside the vessels. This can take a while to take effect, thus the radiologist performing the procedure may insert a small balloon in the veins or arteries to block blood flow in or out of the malformation and keep the drug in place while it works.
Surgery
Surgical resection of an AVM is often difficult and recurrence of the AVM is common with incomplete resection. Therefore, only surgically resectable lesions should be selected for the surgical therapy. Often preoperative embolisation with coils for example may be helpful prior to surgical intervention, due to the increased risk of bleeding associated with such anomalies.
Embolisation and sclerotherapy of an AVM can take a few hours to complete. After treatment you will normally be recovered in our recovery area and then go back to your ward.
Embolisation of an AVM is a safe and effective procedure, but as with any medical procedure complications can arise.
Swelling and pain will occur after the procedure. The swelling and pain should generally settle down after a few weeks; during this time simple analgesia such as paracetamol and/or ibuprofen can be used to control the pain. We will contact you to make sure the pain and swelling after the procedure is not excessive.
If the malformation is close to, or just under the skin, there is a risk of skin blistering or ulceration, and rarely skin loss. Most ulcers will heal of their own accord or may require simple bandaging. However sometimes a skin graft may be required to achieve healing of the skin. Skin loss and ulceration can occur if embolisation of the malformation causes blood flow to be reduced to surrounding or other areas of the body.
Bleeding, swelling and bruising under the skin can be a risk due to the fact we are inserting a catheter into your artery or vein. When we remove the catheter we will press on the area for 10 minutes or so to close the puncture site and prevent bleeding, swelling and bruising.
Nerve damage can occur if the malformation is close to a nerve. This may be in the form of a feeling of numbness, tingling and pins and needles and is usually temporary. However, the nerve may be heavily bruised causing longer term symptoms involving both altered sensation and reduced muscle function, this can be temporary or permanent.
There is always a small risk of bleeding and infection as with any procedure involving needle insertion. Risks are minimised by using image guidance to place the needle in the correct position and by using a sterile technique.
Sclerotherapy causes blood clots within the malformation, rarely the clots can extend into the normal veins resulting in deep vein thrombosis (DVT). If you experience generalised swelling of the whole treated limb or part of a limb such as your calf for example this could be a DVT. You should contact us or your GP immediately to determine if this is the case. If a DVT is confirmed you would normally need to have treatment with anticoagulants (blood thinning drugs) for several months
Other risks
Follow up
Before you commence treatment we will ask you which is the best method for you to be followed up.
We have three methods
- By telephone: We will take the best contact number for yourself.
- By email: We will take the best contact email for yourself.
- By virtual clinic: We can talk to you via a private and secure video link. Again we will need your email to arrange a convenient time to talk.
We will contact you one week and then eight weeks after your procedure to see how you are recovering.
At one week we will ask a number of questions which will enable us to establish how you have been after the treatment and make sure you are not having any problems post procedure or suffering from any complications.
At eight weeks we will discuss if your symptoms have improved or not. We will use this information to determine the next best course of action for you; this is normally either further treatment or a clinic appointment.
If you have any questions or concerns in the meantime please contact:
Clinical Nurse Specialists,
Interventional Radiology & Vascular Anomalies
Please note if you are feeling unwell or unable to contact us regarding any urgent concerns or complications please attend your local GP Surgery, local walk in centre or your local Accident and Emergency Department if appropriate.