Diseases and conditions

Hereditary hemorrhagic telangiectasia (HHT)

What is hereditary hemorrhagic telangiectasia?

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder that results in unusual growth of blood vessels of the mouth, nose, skin, and organs. HHT can be diagnosed based on symptoms, having first-degree relatives with HHT, and/or genetic testing. There are different types of HHT, including arteriovenous malformations (AVMs) and telangiectasias.

Arteriovenous malformations (AVMs): These occur when an abnormal connection forms between the arteries and veins. Arteries carry blood at high pressure and this pressure is usually released when the blood passes to the vein. When the connection between the artery and the vein is not working correctly, the pressure cannot be released and the vein may expand. These veins are then likely to tear. This can cause a variety of effects depending on the location in the body. Below is a list of locations and possible complications associated with AVMs.

  •  Lungs
    • Shortness of breath
    • Stroke and brain swelling
    • Breakage of blood vessels and bleeding, which are potentially life-threatening
  • Brain
    • Seizure and brain bleeds
  • Liver
    • Heart failure and high blood pressure
  • Spine
    • Compression and bleeding in the spinal cord


These are smaller malformations of the blood vessels that occur in the skin as well as inside the nose, the stomach, and intestines. Nosebleeds are a common problem. Additionally, bleeding in the stomach and intestines may cause vomiting, black stool, and eventually a decrease in the amount of red blood cells (anemia). Patients with anemia may feel tired and appear pale.

Interventional radiologists are board-certified physicians who deliver minimally invasive treatments with less risk, less pain and less recovery time than traditional surgery to treat pulmonary AVMs (in the lungs). They use an endovascular (through the blood vessels) approach with the aim of stopping blood flow within the AVM, thereby greatly reducing the risk of complications.

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 Trans-catheter embolization

Pulmonary AVMs are typically first identified on CT scans. Interventional radiologists will use trans-catheter embolization to treat these AVMs.

First, a tiny cut is made in the skin near the groin. A needle is then used to gain access to the large vein in the groin. Once the radiologist gains access, a catheter (a thin flexible tube) is inserted, and dye is then injected through the tubing to be able to identify and locate the AVMs. Once the tubing reaches an AVM, coils are positioned through the catheter in order to stop blood flow within the AVM. Multiple AVMs can be treated during a single treatment.

The vast majority of treatments are successful in treating pulmonary AVMs. Occasionally new blood flow to the AVM may require repeat embolization.

A follow-up CT scan should be performed 3-to-6 months following therapy to see if the AVM is getting smaller.