Hereditary Hemorrhagic Telangiectasia

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What is hereditary hemorrhagic telangiectasia (HHT)?

HHT is a genetic condition that causes blood vessels in part of the body to develop abnormally. Hereditary hemorrhagic telangiectasia is pronounced heh-RED-i-ter-ee hem-or-RAJ-ik teh-lan-jee-ek-TAY-zhuh.

Children with HHT lack the very small tubes (capillaries) that normally connect arteries to veins. Blood in an artery flows under high pressure directly into a vein. Without normal capillaries, this can cause the vein to burst and bleed.

Children with HHT have 2 types of abnormal blood vessels:

Telangiectasias (tee-lan-gik-TAY-zhuhs): Abnormal, enlarged blood vessels in the skin or mucous membranes. They are also called spider veins.
Arteriovenous malformations (AVMs): Tangles of abnormal blood vessels deeper in the body.

HHT is also called Osler-Weber-Rendu syndrome.

What causes HHT?

An abnormal gene causes HHT. Most often, it is passed down (inherited) from 1 parent who has HHT. Each child of a parent with an HHT gene has a 50% chance of getting this gene from their parent.

HHT is a “dominant” disorder. This means it only takes 1 abnormal copy of the gene, from only 1 parent, to cause HHT.

Symptoms of HHT

HHT can cause a wide range of symptoms that vary from child to child and change over time. In most children, symptoms increase as they get older.

Symptoms relate to the 2 types of abnormal blood vessels found in children with HHT:

Telangiectasias in the skin or mucous membranes
Arteriovenous malformations (AVMs) deeper in the body

These abnormal blood vessels cause different symptoms depending on where they are:

Inside the nose. Nosebleeds are the most common sign of HHT. These start in childhood and become more frequent. Nearly everyone with HHT has frequent nosebleeds by the time they are adults.
Skin on the hands, face and mouth. Telangiectasias on the skin look like red lines and sometimes bleed. As a person gets older, more appear. About 95% of all people with HHT have them.
Lining of the stomach and intestines (gastrointestinal or GI tract). About 25% of people with HHT have bleeding in the GI tract, which can range from mild to severe. Your child may vomit up blood or have dark, tar-like bowel movements.
Children with HHT may have telangiectasias in the lining of the lungs. About 30% of people with HHT have an AVM in the lungs, and some have more than 1. Your child may cough up blood.
Children with HHT may have telangiectasias in the lining of the brain. About 15% of people with HHT will develop brain AVMs. Symptoms depend on the part of the brain that is affected. Your child could have headaches, seizures or problems with their hearing or vision.

Vascular Anomalies Care at Seattle Children's

Experts from more than a dozen specialties work together in our Vascular Anomalies Program to make a care plan for your child.

Diagnosing HHT

Since HHT is caused by an abnormal gene, we use genetic testing to diagnose it. Seattle Children’s is 1 of only a few centers in the United States that does genetic testing for HHT. We can help you decide if this blood test is right for your family. Testing for HHT is not a routine part of prenatal genetic testing or commercial testing for ancestry.

To decide if your child should have genetic testing for HHT, the doctor will:

Ask about their medical history and family history
Do a physical exam
Review any past imaging studies or take pictures inside your child’s body using MRI (magnetic resonance imaging), CT (computed tomography) or ultrasound

Diagnosing HHT early is important so we can ease your child’s symptoms and avoid serious problems. Our doctors will work with you and your child to decide on a treatment plan.

A diagnosis of HHT may affect the whole family. We will talk with you about testing for other family members. Unless HHT is ruled out by genetic testing, all children of a parent with HHT should be screened for brain and lung AVMs.

Read more about diagnosing brain AVMs in vascular diseases of the brain.

Treating HHT

There is no cure for HHT. Treatment is aimed at easing or stopping symptoms. Treatment for a telangiectasia or AVM related to HHT depends on its size and location. We treat these abnormal blood vessels if they:

Cause a problem, such as frequent nosebleeds
Have a high risk of causing more severe problems, such as stroke
Are in the lung
Are in the brain

Our treatment options include:

Regular check-ups

Your child’s symptoms may change over time, or they may develop new symptoms. We watch your child closely with regular follow-ups. This helps ensure your child gets the care they need before more serious problems happen.

How often we see your child depends on their symptoms. Some children need regular imaging studies to check their lungs or brain.

After we have fully assessed your child, we follow up every few months. Once our team has a better understanding of your child’s symptoms and they have improved or stabilized, we follow up once a year.
Treating nosebleeds
Nosebleeds are very common in children with HHT. To reduce or prevent nosebleeds we may:
- Give your child medicine to reduce bleeding. Your child may need medicine to keep the inside of their nose moist or to help their blood clot.
- Close off the bleeding vessel by heat, laser or a chemical called silver nitrate. These procedures are called cauterization.
See tips for homecare of nosebleeds and how to tell if your child needs medical care right away.
- Call 911 if your child passes out, is too weak to stand or you think it’s an emergency.
- Seek medical care if the nosebleed does not stop after 10 minutes of pinching the lower nose or if your child has lost a lot of blood.
Laser treatment

Laser therapy is often the best choice for telangiectasias of the nose or skin. It uses light energy to quickly destroy the extra blood vessels. The type of light beam we use depends on the abnormal vessels.

Most patients say the laser feels like a brief sting (like an elastic band snapping against the skin). We treat children with smaller growths in the clinic after using a cream to numb their skin. Children with larger clusters of abnormal vessels often need to be treated in the operating room under general anesthesia. We will talk with you to decide the best choice for your child.

Outpatient laser surgery is done at our Seattle hospital campus, Bellevue Clinic and Surgery Center and North Clinic in Everett. We do laser treatments that need general anesthesia at our Bellevue center or Seattle hospital campus.
Treating AVMs in the lung

AVMs in the lungs are at risk of bursting and bleeding. Someone with a large lung AVM is at high risk for stroke because clots may form, break free and block blood vessels in the brain.

To treat AVMs in the lungs, we use embolization and, rarely, surgery. In embolization, an interventional radiologist puts a small tube (catheter) into a blood vessel and threads it to the target area. Very small coils or plugs are injected into the abnormal blood vessel to block blood flow.
Treating anemia

Bleeding from the stomach or intestines may cause your child to have a very low level of red blood cells (anemia). Your child may need iron supplements.
Treating AVMs in the brain

AVMs in the brain can be life-threatening or disabling if they bleed. Proper diagnosis and screening are essential.

The right treatment depends on the AVM’s size, structure and location. Your child may need surgery, embolization or stereotactic radiosurgery, alone or together.

Read about treating AVMs and other vascular diseases of the brain.

HHT at Seattle Children's

Our Vascular Anomalies Program is nationally known for treating children with HHT and other vascular disorders. We are 1 of the largest and most experienced programs in the United States.

Doctors from throughout the Pacific Northwest send children with HHT here for treatment. We see nearly 2,000 children with vascular anomalies each year, more than any other hospital in the region.

For more information, contact the Vascular Anomalies Program by email or by calling 206-987-4606.

If you would like an appointment, ask your child’s primary care provider to refer you.

Providers, see how to refer a patient.

The experts you need are here
- Few hospitals have our experience treating children with HHT.
- Our Vascular Anomalies team brings together experts with many different skills and experiences. Your child’s care team may include otolaryngologists; geneticists; neurosurgeons; interventional radiologists; plastic surgeons; and experts in the lungs (pulmonologists), skin (dermatologists) and eyes (ophthalmologists). We call in other specialists as needed.
- We also work with experts in psychology, social work, physical therapy, pain medicine and occupational therapy to meet your child’s needs.
- Our physician-scientists help set national standards for care of young people with vascular anomalies. We provide the most advanced treatments in our region.
Accurate diagnosis and advanced care
- A correct diagnosis is the first step toward improving your child's condition. We have the expertise to accurately diagnose your child and decide the best treatment.
- Seattle Children’s is 1 of only a few centers in the United States that can do genetic testing for HHT. We also use a broad range of imaging studies to confirm your child’s diagnosis.
- For children who need surgery to remove abnormal veins in the face, we use facial nerve mapping to greatly reduce the risk of nerve injury and scarring.
- Learn about vascular anomalies research at Seattle Children’s.

Contact Us

If you have questions about a consultation or second opinion, contact the Vascular Anomalies Program by email or by calling 206-987-4606. If you would like an appointment, ask your child’s primary care provider to refer you.