High-Flow Vascular Malformations

High-flow vascular malformations, specifically arteriovenous malformations (AVMs), occur when blood vessels develop abnormally, forming an entanglement between arteries and veins. These malformations bypass the capillary system, disrupting normal blood flow and oxygen circulation. Although AVMs can be found throughout the body, they are notably recognized for their occurrence in the brain.

There are two types:

• Low-flow vascular malformations are lymphatic or venous.
• High-flow vascular malformations are arterial or arterio-venous.

Arteriovenous malformation (AVM) is a high-flow vascular malformation. It is basically an abnormal entanglement of blood vessels or connection between the arteries and veins, which bypasses the capillary system. This disrupts normal blood flow and oxygen circulation. It is widely known because of its occurrence in the brain.

Arteries are responsible for taking oxygen-rich blood from the heart to the body and veins carry the oxygen-depleted blood from the body to the lungs and heart. This process is disrupted by the arteriovenous malformation and the surrounding tissues may not get enough oxygen.

AVM may occur in any part of the body like on the arm, shoulder, face, thigh, leg, etc. They are quite very commonly seen by plastic surgeons on the face, hands, and feet. They can be superficial or deep in location.

Involvement of deeper muscles is quite commonly seen in high-flow vascular malformations.

The symptoms of AVM usually vary with the site of the malformation.

• Generally, most high-flow vascular malformations are asymptomatic and are diagnosed as “Incidental Findings” and the only presentation could be swelling of the region with little heaviness.
• The swelling increases in size on standing and decreases on lying down.
• The swelling will be pulsatile in synchrony with the heartbeat on deeper palpation.
• There are some that cause bleeding, intense pain, or other severe medical conditions.
• There might be abnormal sensations like tingling, numbness, or random pain.
• Difficulties in everyday activities.

The complications related to high-flow vascular malformations vary based on their location and can include:

• Bleeding within the malformation leads to expansion, severe pain, neurological deficits, or sudden enlargement.
• Disfigurement of the affected body part.
• Compression of underlying structures, resulting in symptoms like pain, distal limb ischemia, and swelling.
• Movement coordination issues, sometimes leading to paralysis or muscle weakness.
• Disproportionate enlargement of the body part.

To prevent complications associated with AVMs, early treatment is highly recommended. In most adult cases, a “wait and see” approach is not advisable.

If left untreated, the swelling can become so large that it can involve major blood vessels or vital organs completely. In such cases, surgery is avoided and not done because it may lead to dysfunction of the involved organ which may cause more severe complications.

Diagnosing high-flow vascular malformations often includes:

• Clinical examination, looking for signs such as soft swelling and bluish color.
• Evaluating the size change with body position, noting pulsatile swelling with heartbeats.
• Detection of bruits, which are machinery-like murmurs, during auscultation.

An MRI scan is typically conducted to assess the anatomical extent of the lesion in all planes.

The treatment plan for AVMs depends on the site and onset of symptoms. Surgery is the treatment of choice for high-flow vascular malformations in accessible locations and is usually done by plastic surgeons.

The treatment of AVMS can also be symptomatic. Patients should visit a Neurologist for any seizures headaches or neurological deficits.

Wide local excision surgery is the treatment of choice in AVM with the preservation of surrounding vital structures.

The surgical procedure for high-flow arteriovenous malformation is highly challenging and technically demanding. The procedure requires a lot of preparation from both the patient and the doctor.

During surgery, feeder vessels are identified, ligated and mass is debulked or excised.

Deep-seated AVMs, involving multiple planes and important structures can not be excised completely and usually only debulking is done.

1. Possible complications – should be discussed at length with the operating surgeon as the high-flow vascular malformations are quite deep and involve a lot of nearby important structures.

2. Requirement of more than one stage in excision- Sometimes in a few cases,

• a) if the extent of the malformation is too extensive and deep and
• b) if the excision requires the sacrifice of major vessels or nerves or
• c) if it endangers the survival of the part,
• Then complete excision is not done and part of the malformation which is near the vital structures is left behind so that the function of the part is less disturbed.
• The remaining part can be exercised in a separate stage after a few months.
• d) The method of coverage of the created defect after the excision of malformation should be agreed upon by the patient and his or her attendants.

After removal of the malformation, a defect may be created which may require simple skin suturing or post-surgical reconstruction with flap/skin graft cover.

• a) Skin grafting may be done if the defect is not very deep and vitals structures are embedded deep and not exposed.
• b) Flap Reconstruction which is usually done when any critical part is exposed like bones, tendons, and joints and it becomes really important to preserve them for normal functioning. This can be done with the local flap or microsurgical-free flaps . A well-blood-supplied tissue is taken from the adjacent area or from other areas of the body.

Recurrence rate is high in high flow LARGE or GIANT AVMs as most of the times complete excision is not possible in them and debulking is done to lessen the symptoms of the AVM on the body.