The progression of an AVM is shown. This 6-year-old patient had a stage 1 lesion (A). At 29 years of age he has a stage 3 lesion (B).

AVMs can be localized, regional, or diffuse. They progress through four stages:

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  Stage 1: Warm, skin discoloration, and fast flow on Doppler examination

  
  
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  Stage 2: Growth, palpable pulsations, and enlarged veins

  
  
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  Stage 3: Ulceration, bleeding, and pain

  
  
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  Stage 4: Congestive heart failure

The primary morbidity of AVMs is that their appearance causes psychosocial problems. Other complications occur as they progress: pain, bleeding, and ulceration. Treatments include embolization and/or resection; pharmacotherapy does not exist. Embolization involves cannulation of an artery remote from the AVM (usually the femoral artery) and insertion of an embolic agent into the nidus or draining veins. Generally, embolization is first-line treatment of AVMs; surgical intervention is reserved for small lesions or symptomatic patients after embolization. Most AVMs are diffuse and involve multiple anatomic structures, so complete extirpation is rarely possible; the goal of intervention is usually to alleviate symptoms and control the AVM.

Despite subtotal and presumed “complete” extirpation, most AVMs reenlarge. Recurrence typically occurs during the first year after intervention, and 86% will reexpand within 5 years. Patients who do not have a recurrence 5 years after intervention are likely to have long-term control. However, 5% will experience regrowth more than 10 years after surgery. Patients and families are told that an AVM is likely to recur after resection, and further treatment may be needed in the future.

SURGICAL INDICATIONS

STAGE 1

Stage 1 AVMs typically are not problematic unless they cause a deformity and affect the patient’s self-esteem. Localized lesions should be removed before they progress to a higher-stage AVM. Resection of a stage 1 AVM gives the lowest recurrence rate and best chance for long-term control or cure. Localized lesions are most likely to be removed completely with the least morbidity. Waiting until the lesion expands complicates the resection and reconstruction and increases the likelihood of an unfavorable long-term outcome. If a localized lesion involves an anatomically unfavorable area (for example, the tip of the nose or upper eyelid) that would require complicated reconstruction, leaving a worse deformity than the lesion, I recommend waiting until the AVM worsens and becomes symptomatic in the future. Approximately 16% of stage 1 lesions do not progress long term.

Resection of a regional or diffuse stage 1 AVM should be based on its size and location. Because the entire lesion can rarely be removed, surgical intervention for large asymptomatic lesions is less common. However, if it is possible to completely resect the AVM in an anatomically favorable area (for example, the trunk), prophylactic excision and reconstruction should be considered before the lesion progresses. In contrast, if a large AVM is located on the face and extirpation and reconstruction would leave a significant deformity, it is generally best to wait until the lesion becomes problematic before intervention.

STAGE 2

Stage 2 AVMs are managed similar to stage 1 lesions. However, there is a lower threshold to intervene because the AVM is growing. Stage 2 lesions are more likely to be symptomatic, because they are enlarging. Pulsations from the lesion can also be bothersome to the patient.

STAGES 3 AND 4

Stage 3 or 4 AVMs require treatment for deformity, bleeding, pain, ulceration, and/or congestive heart failure.

SURGICAL MANAGEMENT

TIMING OF INTERVENTION

Stage 3 and 4 AVMs require immediate treatment, regardless of the age of the patient. Milestones for resection of stage 1 and 2 AVMs are: (1) 6 months, (2) 3 years, and (3) late childhood/early adolescence. Generally an AVM should not be removed before 6 months of age. At this time the patient’s risk from anesthesia is greater than for an adult. In addition, a young infant is less able to tolerate a surgical procedure. If a large lesion is located on the scalp, removing it before 6 months of age should be considered to take advantage of scalp laxity that exists during infancy.

If it is likely that a patient will require surgery, a common time I will intervene is between 3 and 4 years of age. Because long-term memory and self-esteem begin to form at approximately 4 years of age, removing an AVM at this time will improve a deformity before the child’s self-esteem begins to form, and the patient will likely not remember the procedure. Another period to intervene is during late childhood/early adolescence when the child is able to communicate whether he/she would like the procedure. if a patient has a minor deformity or a large lesion requiring significant reconstruction, it is often best to wait until the child verbalizes that he or she wants surgery. If the lesion is minor, it may be able to be removed under local anesthesia by waiting until the child is older. If the lesion is significant, then waiting until the child can be a willing participant facilitates the process for the family and surgeon. The surgical strategy for AVMs is based on the extent of the lesion.

LOCALIZED AVMS

A localized AVM involves one to two tissue planes (for example, the skin and subcutaneous tissue), is well defined, and theoretically is able to be entirely removed with linear closure. Unfortunately, these are the least common types of AVMs. Generally, I remove localized AVMs without preoperative embolization, because bleeding is not significant after the area is infiltrated with a local anesthetic containing epinephrine. Avoiding embolization reduces overall treatment morbidity for the patient. If the volume of local anesthetic with epinephrine is limited by the amount of anesthetic that can be given based on the weight of the child, I will infiltrate an epinephrine-only solution to ensure maximum vasoconstriction of the surgical site (1 cc of 1:1000 epinephrine in 200 cc of normal saline = 1:200,000 solution).

Lesions located in anatomically sensitive areas (for example, the face) should have minimal or no margins taken. An AVM is not a malignancy, and evidence does not show that a significant resection margin lowers the recurrence rate. An AVM often involves a larger area than is appreciated clinically and radiographically. Findings of biopsies taken outside of the lesion have shown abnormalities. In my experience if microscopic disease is left after a localized AVM is removed, the recurrence rate is very low. Cautery during the procedure and fibrosis may destroy residual AVM tissue. If a lesion is located in a nonsensitive area (for example, the abdomen), larger margins can be taken as long as they do not complicate the extirpation and reconstruction (see Video 10-1, Arteriovenous Malformation).

REGIONAL AVMS

The borders of an AVM can be difficult to determine, because the periphery of the lesion may be pinkish-red from inflammation and/or reactive hyperemia. It is preferable to have minimal, if any, margins when a lesion is resected from an aesthetically sensitive area. Intraoperatively subcutaneous tissues can be cauterized at the periphery of the AVM without removing skin. Recurrence is low when completely resecting regional AVMs, even without margins.

Unlike localized AVMs, regional lesions should have preoperative embolization to reduce intraoperative blood loss and facilitate the procedure. Our center prefers Onyx, and I schedule the resection within a week of the embolization before neovascularization resupplies the AVM. Blood loss is further reduced by: (1) infiltrating the operative area with epinephrine, (2) using epinephrine-soaked sponges during the procedure, (3) using a tourniquet for extremity lesions, (4) using iced saline solution intraoperatively to promote vasoconstriction, (5) keeping the surgical area elevated and the patient’s blood pressure low, and (6) incorporating clips to prevent skin edge bleeding (particularly scalp lesions). The extirpation proceeds carefully by incising a localized area and controlling bleeding before continuing. Long, deep incisions should not be performed because of the risk of significant blood loss. Generally regional AVMs bleed less than diffuse lesions, because the edges of the defect are disease free. None of the patients with an AVM on whom I have operated has required a blood transfusion with these techniques.

Complete removal of a regional AVM requires reconstruction with grafts or flaps. Skin grafts are best placed on a recipient site that is free of disease. If the underlying area contains an AVM, the graft has a higher chance of failure, because the wound bed is ischemic. An AVM causes shunting of blood directly from the arterial to the venous circulation (a capillary bed is not present), and thus oxygenated blood is not delivered to the tissues. If the recipient site is considered significantly involved with an AVM, flap reconstruction is preferred because of the high likelihood of graft failure.

DIFFUSE AVMS

Diffuse AVMs are unable to be entirely removed without causing significant morbidity. These lesions had been previously treated in our center with wide resection and free tissue transfer. Unfortunately, the AVM had a high recurrence rate, and the reconstruction caused patients to have a worse deformity than the appearance of the AVM. Consequently, my philosophy changed to managing these patients with: (1) embolization only for palliation of bleeding, pain, or ulceration or (2) subtotal excisions of symptomatic areas.

If the primary morbidity is bleeding or a chronic wound, the definitive intervention should be embolization. This treatment effectively reduces the risk of bleeding and shunting of oxygenated blood. Symptoms are likely to recur, but patients may achieve long-term control of bleeding and ulceration. Individuals often desire an improvement in their appearance or have focal problematic areas (for example, pyogenic granulomas or overgrowth of specific structures). The only way to improve their appearance or eliminate areas of overgrowth is resection.

PATIENT EXAMPLES

LOCALIZED AVM

Patient A