Hereditary hemorrhagic telangiectasia (tuh-lan-jee-uk-TAY-zhuh), also known as HHT or Osler-Weber-Rendu syndrome, is an inherited disorder that affects blood vessels. In most cases, HHT isn't life-threatening. Currently there's no cure, but in many cases the symptoms can be effectively managed.

In people who have HHT, most of the body's blood vessels are normal. But some of the networks of blood vessels that join arteries to veins (capillaries) aren't correctly formed. In small blood vessels, these abnormalities are called telangiectases. When they occur in larger vessels, they're called arteriovenous malformations (AVMs). People who have HHT may have both kinds of malformations.

Telangiectases and AVMs cause health problems because they don't function normally. This can lead to a variety of symptoms depending on where the blood vessel abnormality is located. In some areas of the body — especially the lungs, brain and liver — these blood vessel abnormalities can be serious because they may bleed, don't allow for adequate oxygen levels in the blood, and can increase your risk of brain infections and stroke. Nosebleeds and bleeding within the intestines can also lead to anemia. The severity of HHT often varies significantly from person to person, even within the same family.

Mayo Clinic is an HHT Center of Excellence. An HHT Center of Excellence is a medical center that has been designated by the HHT Foundation International as an institution that can provide comprehensive care to meet all the medical needs of HHT patients.

At Mayo Clinic in Minnesota, specialists from across departments work together to diagnose and treat patients with HHT. These include specialists in medical genetics, pulmonary medicine and critical care, neurology, neurosurgery, ear, nose and throat (ENT), radiology, and gastroenterology and hepatology.

In addition, Mayo Clinic has one of the few clinical laboratories in the United States that performs the two most commonly ordered genetic tests for HHT, should you choose to use genetic testing to guide your family's care.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

Specialists in medical genetics, pulmonary medicine and critical care, neurosurgery, ear, nose and throat (ENT), and gastroenterology and hepatology work together to treat people who have HHT.

For appointments or more information, call the HHT clinic scheduler, in the Division of Pulmonary Medicine and Critical Care, at 507-266-0416 between 8 a.m. and 5 p.m. Central time, Monday through Friday, or complete an online appointment request form.

Specialists in medical genetics, neurosurgery, ear, nose and throat (ENT), and gastroenterology and hepatology work with specialists in pediatric pulmonology to help treat children diagnosed with HHT.

For appointments or more information, call the HHT clinic scheduler, in the Division of Pulmonary Medicine and Critical Care, at 507-266-0416 between 8 a.m. and 5 p.m. Central time, Monday through Friday, or complete an online appointment request form.

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

A diagnosis of HHT can often be made based on a physical examination, results of imaging tests and a family history. However, some symptoms may not yet be apparent in children or young adults at the time another family member is diagnosed with HHT.

Signs and symptoms of telangiectases and AVMs include shortness of breath, recurrent headaches, seizures, vision changes, anemia and blood in the stool. Symptoms depend on the location of the AVM.

A clinical diagnosis of HHT can be made if you have at least three of these four criteria:

  • Recurrent nosebleeds that seem to start for no reason
  • Visible telangiectases on your lips, the inside of your mouth, your fingers or your nose
  • Internal telangiectases or AVMs on your lungs, brain, digestive tract or liver
  • Family history of a parent, sibling or child with HHT

Genetic testing is available to identify the genetic cause of HHT and may sometimes help confirm a suspected diagnosis. If the test confirms the genetic cause of your HHT, this information can be used to test other family members to determine who needs to seek medical care for HHT health risks. The first step in undergoing genetic testing is to consult with a certified genetic counselor or medical geneticist. The genetic specialist will take a detailed family history, provide information about HHT, and discuss with you how genetic testing may be useful for you and your family.

It's likely your doctors will order imaging tests to check for telangiectases and AVMs as a part of your diagnosis. These imaging tests can include:

  • Chest X-ray. A chest X-ray can help your doctor see the size, shape and structure of your lungs, and can give clues about the location and severity of any AVMs.
  • Magnetic resonance imaging (MRI). Your doctor may order an MRI scan to check your brain for any abnormalities in your blood vessels. MRI is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. It's possible your doctor may give you a special type of dye (contrast medication) to make your blood vessels show up easily on the images produced by your MRI.
  • Bubble echocardiogram. To screen for any abnormal blood flow caused by an AVM in your lung, your doctor may recommend this test. An echocardiogram uses sound waves to examine the blood flow through your vessels. In a bubble echocardiogram, you'll receive an injection of saline solution that has air bubbles in it, making it easier for your doctor to see how your blood is flowing and if there may be any vessel malformations.
  • Computerized tomography (CT) scan. A CT scan combines a series of X-ray views taken from many different angles and computer processing to create cross-sectional images of the bones and soft tissues inside your body. If a bubble echocardiogram reveals you may have a lung AVM, your doctor may order a CT scan of your lungs to confirm the diagnosis and see if your AVM needs any treatment, such as surgery. Your doctor may also order a CT scan of the abdomen to look for telangiectases in the liver.

People who have HHT should seek treatment at a medical center with experience treating this disorder. Because the disorder is uncommon, finding a specialist in HHT can be difficult. In the United States, HHT Centers of Excellence, including Mayo Clinic, are designated by the HHT Foundation International for their ability to diagnose and treat all aspects of the disorder.

Although no cure exists, doctors can treat the symptoms of HHT and help avoid serious complications caused by abnormal blood vessels. HHT treatment often depends on which parts of the body are affected.


Telangiectases in the nose can cause bleeding that ranges from minor to severe. Minor nosebleeds may respond to home remedies, such as humidifying the air or using moisturizing nose sprays or drops. Treatments for more-serious nosebleeds include:

  • Laser treatment. During laser coagulation therapy, a small beam of laser light is directed around the margins of telangiectases. This destroys and seals off the vessels that are bleeding.
  • Septal dermoplasty. During this surgical procedure, the mucous lining of the nose is replaced with a graft of thicker skin. This procedure permanently removes the natural lining of the nose.
  • Hormonal therapy. In some cases, your doctor may prescribe hormone medications to help control nosebleeds. This may slow down bleeding, but is often not successful.
  • Blocking an artery (embolization). This procedure, called embolization, blocks off an artery that carries blood to the malformed vessel. This is usually only effective for six to eight weeks because other arteries will replace the blocked one.


Often, telangiectases require little more than medical monitoring. Telangiectases that bleed and discolor the skin are usually treated with laser therapy. The laser beam can selectively destroy the discolored tissue.

Stomach and intestines

Bleeding in the stomach or the intestines is often difficult to treat due to the large number of telangiectases that may occur in the gastrointestinal tract. Telangiectases can be treated with laser, a heater probe, hormonal treatment or a combination of therapies. Anemia caused by blood loss is typically treated with iron supplements or blood transfusions.


AVMs in the lung should be treated before they cause symptoms. To treat lung AVMs, doctors may perform an embolization through a procedure called a pulmonary angiogram. In a pulmonary angiogram, a radiologist will first guide a thin tube (catheter) through a needle insertion in the groin to the AVM. At this point, the radiologist does an embolization by placing a tiny balloon or coil to seal off the AVM and block it from the body's circulation.


Treatment for AVMs in the brain depends on their size, location and how they are formed. Treatments include surgery, embolization, stereotactic radiosurgery and, in some cases, observation.


Because treating vessel malformations in the liver can sometimes lead to serious complications, the decision to treat the liver is evaluated for each person. Options may include liver transplantation in rare cases.

Mayo Clinic is a leader in HHT research, in areas such as improving imaging techniques to find vessel malformations, developing new medical procedures to correct vessel malformations, understanding pregnancy risks related to HHT, and helping families communicate about HHT and genetic test results.


See a list of Mayo publications on PubMed, a service of the National Library of Medicine.

Jan. 07, 2013