Peripheral Vascular Malformations

Vascular Malformation is a general term that includes congenital vascular anomalies of only veins, only lymph vessels, both veins and lymph vessels, or both arteries and veins:

  • Only veins: Venous Malformations (VM)
  • Only lymph vessels: Lymphatic Malformations (LM)
  • Both veins and lymph vessels: Venolymphatic Malformations (VLM)
  • Arteries connected directly to veins without any capillaries in between: Arteriovenous Malformations (AVM)

These are all present at birth, and become apparent at different ages. We are just beginning to understand how malformations occur. The pulmonary arteriovenous malformation, when associated with Hereditary Hemorrhagic Telangiectasia, is inherited genetically. There is currently much work being done on the possible genetics of other malformations. Most are only known as something that occurs during development of the arteries, veins, and/or lymph vessels, but without specific cause.

Symptoms

These vascular malformations can cause a variety of symptoms, depending on the location in the body:

Venous malformations (VMs) may cause pain wherever they are located. VMs and lymphatic malformations (LMs) may cause a lump under the skin. There may be an overlying birthmark on the skin. Bleeding or lymph fluid leaking may occur from skin lesions. LMs tend to become infected, requiring repeated antibiotic treatments. VMs and LMs may be associated with a syndrome called Klippel-Trenaunay Syndrome.

Arteriovenous malformations (AVMs) may cause pain. They are also more stressful on the heart because of the rapid shunting of blood.

Pulmonary arteriovenous malformations (PAVMs) are somewhat different in that they shunt blood from the right heart system to the left heart system without picking up oxygen in the lungs. This results in symptoms of low oxygen, shortness of breath, and fatigue. These malformations may also bleed, resulting in coughing up blood or blood in the chest. Also, these pulmonary artery to pulmonary vein shunts can allow clots to pass through the lungs and travel to the arteries in the body, with risk for stroke or brain abscess. This is a very significant reason to block these shunts.

Treatment of Vascular Malformations

Although surgery is sometimes useful, it is usually difficult for surgeons to completely remove vascular malformations, which will return if not removed completely. A nonsurgical method of closing down the blood or lymph flow into the malformation is done by interventional radiologists, who treat patients with image-guided procedures. Vascular malformations are treated by embolization.

The AVMs can be closed by advancing a tiny plastic tubing, no larger than a pencil point, into the feeding artery to the malformation. This can be done without incisions or stitches, and with only mild sedation. Medical glue, or alcohol, or small beads are then floated into the malformation until it is full and no longer has blood flowing through it.

AVMs tend to pull in new artery feeders from time to time. However, embolization is very effective in blocking abnormal artery feeders while preserving normal arteries. AVMs may require a series of treatments to block all of the abnormal feeders.

PAVMs are very effectively treated by embolization, which blocks only the abnormal artery feeder, and preserves the normal lung arteries. Patients usually notice an immediate improvement in symptoms with the immediate increase in oxygen level. All vascular malformations require long-term surveillance.

Embolization techniques have been used extensively all over the world for the past 30 years. They have been well established for many years, and have proved invaluable in treating vascular malformations.

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Hereditary Hemorrhagic Telanglectasia (HHT)

Hereditary Hemorrhagic Telanglectasia (HHT) is a genetic disorder that affects about one in 5,000 people and causes arterial blood to flow directly into the veins, creating weakened ballooned vessels that can rupture. Interventional radiologists are one of the few specialists who can treat this disease that affects approximately half a million people worldwide. As vascular experts, interventional radiologists perform embolization—blocking the blood flow to the affected area to prevent a life-threatening rupture.

Most patients with HHT function normally. Forty percent have brain or lung involvement that may lead to unexpected severe complications. Physicians treating complications often don’t realize that the underlying disorder is HHT. As a result, most patients are undiagnosed.

Overview of Circulatory System and HHT

In the normal circulatory system, arteries take oxygenated blood from the heart and push it out to all parts of the body under high pressure, while the veins return the blood back to the heart. Small capillaries typically connect the arteries to the veins. A person with HHT lacks capillaries in a few blood vessels in critical locations. Arteries connect directly into veins, creating a fragile site that can rupture and bleed. These abnormal blood vessels are called telangiectasia (tel-AN-jee-eck-TAZE-ee-ya) if they involve small blood vessels (nose, stomach, and small bowel) and AVMs if they involve a larger blood vessel (lung, brain, and liver). Telangiectases often occur near the surface of the skin like the mucous membrane in the nose while AVMs appear in the internal organs of the body.

HHT Symptoms Vary With Location

The location of the telangiectases or AVM impacts what problems a person with HHT might face. A person with abnormal GI tract blood vessels should watch for black stools and anemia that can cause fatigue, shortness of breath, chest pain, or lightheadedness. Those with AVMs in the lung face the possibility of a life threatening rupture, stroke, or brain abscess—especially during pregnancy. HHT patients with brain AVMs do not generally have warning symptoms prior to a life-threatening brain hemorrhage. Heart failure is another risk HHT patients face due to high-flow AVMs.

Regardless of location or size, abnormal blood vessels have a greater tendency to rupture and bleed compared to normal blood vessels and should be closely monitored.

Those with HHT may have blood vessel abnormalities in the:
  • Nose
  • Skin of the face, hands, and mouth
  • Lungs
  • Brain
  • Lining of the stomach and intestines (GI tract)

Prevalence

  • About 95 percent of those with HHT have recurring nosebleeds.
  • Ninety percent of HHT patients have telanglectases in the skin of the hands, face, and mouth that generally become apparent in their 30s or 40s.
  • GI bleeding will develop in about 25 percent of HHT patients (after age 50), which can result in black stools or anemia.
  • 30 percent will have one or more AVM in the lung that is life threatening, should it rupture. Pregnant women with HHT are at increased risk of AVM rupture in the lung due to an increase in blood volume and cardiac output in the last trimester. Patients with lung AVMs are also at risk for stroke or a brain abscess from the lack of capillaries to filter impurities like clots, bacteria, and air bubbles. Brain AVMs are found in 15 percent of HHT patients and can be life threatening.
  • Spinal AVMs are fairly rare and cause back pain or loss of feeling/function in arms and legs.

Recurrent Nosebleeds are Most Common HHT Symptom

Approximately 95 percent of HHT patients eventually have recurrent nosebleeds, with one-third having onset by the age of 10 and 90 percent by age 21. Other characteristics of HHT include small red to purple spots and lacy red vessels.

HHT, Women, and Pregnancy

Female hormones are known to affect bleeding of abnormal HHT blood vessels. For some women, nosebleeds vary through the menstrual cycle and become worse after menopause.

Most pregnant women with HHT can expect no serious HHT-related complications. For some, new skin telangiectases are detected, while others report improvements. There is great concern for pregnant women with an AVM in their lung. During pregnancy, there is a 60 percent increase in blood circulation that is essential to the development of the baby. This increase in pressure on weak abnormal blood vessels increases the risk of a life threatening rupture in the lung. Research shows that it is safe and efficacious to perform embolization on pulmonary AVMs during the second trimester of pregnancy.

Both HHT mothers and their babies can generally expect a safe pregnancy.

Diagnosis

In the mid 1990s scientists discovered that an abnormal gene on either chromosome 9 or 12 causes HHT. Chromosome 9 (endoglin) and chromosome 12 (activin-like kinase) tell the body to produce a substance that is involved in the formation of blood vessels. HHT is a “dominant” disorder since one abnormal copy of the gene from one parent can cause the disorder. Although there is a 50 percent chance of inheriting this abnormal gene, children who do not have it cannot pass on the disease.

In 2003, genetic testing for HHT became available at only a few genetics laboratories in the United States. The complicated family-based testing should be run, ordered, and managed by an HHT Center or genetics professional. According to recently published Clinical Diagnostic Criteria, a person has HHT if they have three or more of the following criteria and are suspect if they have two or more of the criteria:

  • Nosebleeds are spontaneous and recurrent
  • Telangiectases are prevalent at characteristic sites such as lips, oral cavity, fingers, and nose
  • AVMs are present in lung, brain, GI, liver, or spine
  • Family history indicates a parent, sibling, or child has HHT

Interventional Radiologists Treat Malformations Nonsurgically With Embolization

The location of the telanglectases determines the course of treatment for HHT patients. Interventional radiologists treat malformations in the lung and brain using embolization.

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Lung Treatment

These malformations should be treated, even prior to symptoms appearing, due to their life threatening/disabling nature. Interventional radiologists, vascular experts who treat patients internally using imaging to guide them, can permanently treat lung AVMs using a minimally invasive procedure known as embolization. During this procedure, an interventional radiologist makes a small nick in the skin, inserts a catheter into the femoral vein in the groin and then directs it to the abnormal blood vessels in the lung. Next, Dacron platinum coils are placed in the artery feeding the AVM to permanently block the blood flow to the AVM. Patients should be seen one year after treatment by the interventional radiologist to be sure the AVM has been resolved.

Embolilzation is performed with local anesthesia and conscious sedation.

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