OVERVIEW

What is arteriovenous malformation?

Arteriovenous malformations (AVMs) occur when the capillary bed that should normally connect arteries and veins is missing, leading to abnormal direct connections between them. High-pressure arterial blood flows into local venous vessels, causing symptoms such as abnormal pulsation, elevated skin temperature, and tremors at the affected vascular site.

AVMs are congenital conditions and a type of vascular malformation. Approximately 60% of patients are diagnosed at birth^[1], while the remaining cases manifest gradually in adulthood. AVMs can affect various parts of the body, such as cerebral AVMs, corpus callosum AVMs, peripheral AVMs, and uterine AVMs.

How common are arteriovenous malformations?

Relatively common.

Current epidemiological studies indicate that the global incidence of AVMs is about 4.5%, meaning roughly 5 out of 100 people have AVMs^[2].

What are the stages of arteriovenous malformations?

Based on clinical manifestations, AVMs can be divided into four stages^[3]:

• Stage I (Quiescent phase): Usually asymptomatic, spanning from birth to adolescence. Symptoms may include port-wine stains on the skin, with redness and warmth upon touch.
• Stage II (Progressive phase): Typically begins during adolescence, with lesion expansion, localized skin darkening, and palpable pulsations or tremors.
• Stage III (Destructive phase): Symptoms include skin pain, ulcers, bleeding, and infections.
• Stage IV (Decompensated phase): Progresses to congestive heart failure, presenting as palpitations, shortness of breath, and chest tightness.

What is the difference between arteriovenous malformations and hemangiomas?

Both are congenital conditions that can affect the skin, soft tissues, and may progress to heart failure. However, their causes differ. AVMs result from abnormal connections between arteries and veins, whereas hemangiomas are caused by mutations in arterial or venous endothelial cells.

What are the risks of arteriovenous malformations?

The risks vary depending on the affected area. Soft tissue AVMs may cause cosmetic issues, skin redness, ulcers, or bleeding. Cerebral AVMs can lead to seizures, paralysis, or aphasia in addition to bleeding. Most visceral AVMs are asymptomatic, though some may cause pain or bleeding.

Which department should I visit for arteriovenous malformations?

Since AVMs can occur in different locations, the appropriate department depends on the affected area. Options include dermatology, vascular surgery, interventional radiology, neurosurgery, general surgery, plastic surgery, maxillofacial surgery, or orthopedics. If unsure, consult a nurse at the hospital's guidance desk for assistance.

SYMPTOMS

What are the common manifestations of arteriovenous malformations?

Arteriovenous malformations (AVMs) can occur in various parts of the body, such as cerebral AVMs, corpus callosum AVMs, peripheral AVMs, and uterine AVMs. The manifestations differ depending on the location. Since it is difficult to enumerate all specific sites, they are clinically categorized into soft tissue, bone tissue, and visceral AVMs^[1].

1. Soft tissue AVMs: Soft tissues refer to tissues surrounding organs, such as skin and muscles. Symptoms may include skin erythema, swelling, and pain. Some individuals may also observe a network of dark red or pink fine blood vessels on the skin surface. Around the lesion, tortuous, worm-like veins may be visible, and the skin may feel warmer to the touch.

   Most patients experience varying degrees of skin ulceration and infection. Severe cases may lead to significant asymmetry in calf size, affecting appearance. During palpation, a pulsating sensation and increased skin temperature may be detected, which are characteristic of AVMs. Ultrasound examinations reveal low-flow venous malformations, whereas AVMs are distinctly high-flow lesions.

   If the soft tissue AVM is in the head or neck, turning the head to the healthy side may reveal prominent blood vessels on the affected side. As the condition progresses, symptoms of congestive heart failure, such as palpitations, shortness of breath, and chest tightness, may occur. If the AVM is in the limbs, visibly enlarged, tortuous blood vessels may be observed.

2. Bone tissue AVMs: These commonly occur in the maxilla or mandible (jawbone), presenting as recurrent, minor bleeding or occasionally acute bleeding. They typically manifest around the age of 10 during tooth replacement or extraction, which may trigger bleeding. Frequent bleeding requires medical evaluation, with follow-ups advised until around age 18. AVMs in other bones, such as ribs, are rare.

3. Visceral AVMs: These are relatively uncommon, with occasional reports involving the kidneys, lungs, gastrointestinal tract, or pelvis^[1]. Patients are usually asymptomatic or exhibit mild, nonspecific symptoms such as localized soreness, pain, pulsations, or bleeding, requiring clinical differentiation.

The clinical manifestations of AVMs vary by location, but bleeding is the predominant symptom. Severe bleeding may lead to hemorrhagic shock, posing a life-threatening risk. For example, cerebral AVMs may cause subarachnoid or intracerebral hemorrhage, accompanied by vomiting and impaired consciousness, worsening with physical exertion or emotional stress.

Additionally, patients with cerebral AVMs may experience progressive neurological dysfunction, such as motor or sensory deficits, cerebral edema, or atrophy. If the AVM is in the stomach or duodenum, gastrointestinal bleeding may occur, leading to chronic anemia, acute hematemesis, or melena. Severe cases can result in hemorrhagic shock, endangering life.

CAUSES

What are the common causes of arteriovenous malformations?

The pathogenesis of arteriovenous malformations is not yet fully understood. It is currently believed to be related to abnormal vascular development during early pregnancy. As age increases, the abnormal blood vessels gradually develop and may only be detected at a certain stage. However, the condition may progress more rapidly in patients during puberty or pregnancy^[4].

Who is more likely to develop arteriovenous malformations?

1. Children: Typically, arteriovenous malformations are present at birth, but most cases show no clinical symptoms until childhood when noticeable symptoms appear.
2. Adolescent or pregnant women: Hormonal changes in the body may accelerate disease progression.
3. Individuals with trauma or surgery: External stimuli may also speed up the progression of the condition.

Are arteriovenous malformations contagious?

No.
Arteriovenous malformations are not caused by bacterial or viral infections and cannot be transmitted through air or other means.

Are arteriovenous malformations hereditary?

Possibly. There have been a few reports of familial arteriovenous malformations, revealing different genetic types and clinical manifestations^[5]. However, most cases occur sporadically and are not strongly linked to family heredity. Further research is needed to confirm any genetic association.

DIAGNOSIS

How to Diagnose Arteriovenous Malformation? What Tests Are Needed?

Clinicians will carefully inquire about medical history, such as the duration of skin ulcers and whether there is pain. They will examine the skin condition of the affected area. Since arteriovenous malformation lacks specific symptoms, additional diagnostic tests are required, primarily including color Doppler ultrasound (CDFI), contrast-enhanced CT, MRI, and digital subtraction angiography (DSA).

1. Color Doppler Ultrasound: This is the most commonly used diagnostic method. Patients with arteriovenous malformation exhibit differences in blood flow velocity and volume compared to healthy individuals. Additionally, some malformed vessels may not be visible to the naked eye, but abnormal blood flow can still be detected via ultrasound.
2. Contrast-Enhanced CT and MRI: These tests help identify the location of the lesion, abnormal blood flow velocity in malformed vessels, and whether the malformation has affected surrounding tissues. They play a crucial role in clinical diagnosis.
3. Digital Subtraction Angiography (DSA): Compared to ultrasound and CT, DSA provides a more intuitive and clearer visualization of the shape of arteriovenous vessels and whether they are dilated. However, as an invasive procedure, it is not typically performed alone but is often used in conjunction with interventional treatment.

TREATMENT

How to treat arteriovenous malformation?

The key to treatment is to eliminate or alleviate abnormal venous hypertension, primarily through interventional embolization, supplemented by laser therapy and surgery.

1. Interventional embolization: The doctor guides a microcatheter to the malformed vascular mass, determines the exact location through angiography, observes the blood vessels, measures blood flow velocity, and then places an embolic agent to occlude the vascular lumen or block blood flow. This is similar to placing a large rock in the middle of a small river—the water flow decreases, and without nourishment from the water, aquatic plants cannot grow. Similarly, once the lesion loses blood flow, it gradually atrophies, leading to symptom improvement or recovery.

   However, interventional therapy cannot completely remove the lesion, so most patients experience recurrence. Follow-up examinations are required at 3 months, 6 months, and 12 months after treatment. Generally, if there is no recurrence within 5 years, the condition is considered relatively stable.

2. Laser therapy: Typically suitable for mild cases, such as when superficial color changes remain visible on the skin after interventional embolization or when the arteriovenous malformation is limited to the surface. It can help improve skin color.

3. Surgery: The most direct approach but carries higher risks. If the affected area is small and not in a critical region, surgical removal can be performed with the assistance of interventional embolization.

4. Targeted therapy: Research is ongoing to identify potential targeted drugs for arteriovenous malformations^[6], but further studies are needed for confirmation.

Can brain arteriovenous malformation be treated with surgery?

Yes, but it depends on the specific case. If the affected area is small and not in a critical region, surgical removal can be performed with the assistance of interventional embolization.

Can arteriovenous malformation be completely cured?

Yes, but if the vascular malformation is large or the venous drainage flow is too high, a complete cure may not be possible, and there is a high recurrence rate^[1].

DIET & LIFESTYLE

What should be noted after arteriovenous malformation surgery?

1. Appropriately consume more high-energy and high-fiber foods, such as eggplants; avoid spicy and irritating foods, such as chili peppers.
2. Engage in early ambulation to reduce the risk of pulmonary infections and deep vein thrombosis in the lower limbs.
3. Keep the surgical site clean and dry to avoid infection.
4. Maintain a positive mood and avoid negative emotions.
5. Take medications on time, monitor postoperative recovery, and attend regular follow-up examinations.

What dietary precautions should arteriovenous malformation patients take?

1. Reduce intake of refined carbohydrates, such as white rice, and prioritize fiber-rich diets to minimize factors like constipation that may increase abdominal pressure, thereby avoiding triggers for arteriovenous malformation rupture.
2. Avoid strenuous exercise; opt for aerobic activities like yoga or jogging.
3. Avoid emotional anxiety and maintain physical and mental well-being through fitness, music, and healthy social interactions.

What psychological precautions should arteriovenous malformation patients take?

Arteriovenous malformation patients are mostly infants, children, and young adults. The condition initially manifests as skin changes, which can affect appearance to varying degrees, leading many patients to experience distress, depression, frustration, and other pessimistic emotions. However, as public awareness of its psychological impact remains limited, health education for patients' families is essential.

Parents of affected children are encouraged to seek treatment before school age to prevent the development of low self-esteem or distress later in life.

Adult caregivers should provide psychological support during medical consultations, such as through active listening and companionship, to alleviate negative emotions. Severe cases may require professional psychotherapy.

PREVENTION

Can arteriovenous malformation be prevented? How to prevent it?

There are currently no effective preventive measures. Arteriovenous malformation is a congenital disease with unknown specific causes.

It is currently believed to be possibly related to abnormal vascular development in early pregnancy. It is recommended to quit smoking and drinking during pregnancy preparation and gestation, avoid exposure to harmful substances and radiation, and maintain a relaxed mood, which may help avoid abnormal vascular development to some extent.