What is hereditary hemorrhagic telangiectasia?
Hereditary hemorrhagic telangiectasia (HHT), also called Osler-Weber-Rendu disease, is a vascular condition that causes malformed blood vessels. Blood vessels (including arteries, veins and capillaries) are the tubes that carry blood through the body. Arteries move oxygen-rich blood from the heart out to the arms and legs. Veins move oxygen-poor blood back to the heart.
Normally, people have tiny capillaries that connect high-pressure blood in arteries to low-pressure blood in veins. Capillaries help decrease the pressure from arteries to veins. When someone has HHT, they can develop areas where blood flows directly from arteries to veins, skipping the capillaries. When arteries and veins form these direct connections, the malformation is called an arteriovenous malformation (AVM). AVMs are high-pressure, delicate connections that increase the risk of bleeding. AVMs may occur in many different organs in the body.
What causes HHT?
HHT is caused by genetic changes (mutations) that most often occur in one of three genes (ACVRL1, ENG and SMAD4). Three other genes have recently been reported to cause HHT-like disorders (GDF2, RASA1 and EPH4). About 10% to 15% of people with HHT will not have a change in any gene.
HHT is a dominant condition, which means that if a person has HHT, they have a 50% chance of passing it on to each of their children. It is very common for multiple family members to have the disease.
What are the signs and symptoms of hereditary hemorrhagic telangiectasia?
HHT signs and symptoms can develop any time from early childhood to much later in life. They may include:
- Frequent nosebleeds
- Small red spots that may look like pin pricks, called telangiectasias, on the nose, hands, face and mouth
- Fatigue and shortness of breath, which can be caused by anemia, a condition in which the blood does not carry enough oxygen to the rest of the body
- Blood in the stools or dark stools, which can be caused by GI bleeding
What tests are used to diagnose HHT?
There are several ways we can diagnose HHT. When we first meet with your child, we will ask about their health and their family’s health. Based on the information we gather during this visit, we will develop a plan regarding screening, imaging and genetic testing.
The most common tests for diagnosing and monitoring HHT include:
- CT scans use X-ray equipment to create detailed images of your child's organs, bones, soft tissues and blood vessels. If your child needs a CT scan, the facilities at Children’s Hospital Colorado are equipped to ensure that children receive the lowest amount of radiation possible while receiving an accurate diagnosis.
- An MRI uses magnetic field and radio waves to create images of many different parts of the body.
- An ultrasound (also called sonography) uses high-frequency sound waves to produce images of the inside of your child’s body.
- A blood test is done by drawing a sample of blood from a child’s arm or hand.
You can discuss genetic testing for HHT with your healthcare team. While a positive test result confirms that someone has HHT, a negative result will require further interpretation. Not all genetic mutations are known.
What to expect from tests used to diagnose HHT
- A CT scan is usually a fast exam and children generally usually do not need anesthesia. We may use a contrast material for some CT scans so we can see areas of the body in greater detail. Your child may need an IV so we can give the contrast material. Our team takes great care and uses child-specific instruments to make the experience as painless as possible.
- An MRI can be a long and noisy exam, so our specially trained pediatric anesthesiologists can provide sedation to your child to make the exam more comfortable. Sedation allows us to get the best image to ensure an accurate diagnosis.
- An ultrasound is a well-tolerated, painless and fast test. It generally takes under 10 minutes.
- A blood test requires a fast and minimally painful poke in the arm or hand to obtain a sample. While no one likes getting their blood drawn, we use smaller needles and our healthcare providers are fast and well-trained on how to get the sample as quickly as possible.
How do we diagnose HHT?
We use the Curaçao diagnostic criteria for HHT. If three of the four criteria items below are true for your child, that child is considered to have a definitive diagnosis of HHT. If two of the criteria are met, a diagnosis of HHT is possible. If there are fewer than two criteria, then the diagnosis is unlikely to be HHT.
The criteria are as follows:
- Recurrent and spontaneous nosebleeds
- Multiple telangiectasias on the skin of the hands, lips, face or inside the nose
- Arteriovenous malformations in one or more internal organ such as the lungs, liver, brain or spine
- A family history of HHT
How is HHT treated?
HHT is treated based on the symptoms it is causing:
- Nosebleeds: An otolaryngologist from our ear, nose and throat department with special training in HHT will evaluate and manage nosebleeds. We use different strategies to manage nosebleeds caused by HHT than we do for regular nosebleeds. If nosebleeds are severe, there are some types of medicines that our team can prescribe to help them stop. Some strategies we use to manage nosebleeds include:
- Use of a humidifier
- Use of a water-based nasal lubricant
- Coagulation therapy
- Oral or topical medical therapies currently being investigated
- Arteriovenous malformations (AVMs): Some AVMs do not need treatment, so we may only observe and monitor them. Other AVMs will require embolization, which is a procedure that we use to shut down AVMS that occur in the brain, lungs or liver. This procedure is less invasive than surgery. We use a catheter to place a small amount of glue or a coil inside the AVM to seal it and prevent the risk of bleeding. In some cases, surgery to remove the AVM is needed.
If your child is experiencing recurrent or severe bleeding, we may need to do blood tests to monitor the effect on your child’s body. Some children need iron or blood transfusions for severe bleeding.
Why choose us for treatment of HHT?
At Children’s Colorado, we have a special team of providers who are experts in diagnosing and treating HHT. Our clinic focuses solely on caring for these complex patients. Our team will review your child’s information before meeting with you, so your visit is as efficient as possible. We also make visits efficient by coordinating the care of patients who must travel long distances to come to our clinic because treating HHT can involve appointments with several different specialists.
When the time comes to transition your child to an adult hospital, we work closely with colleagues at the University of Colorado HHT Center to make the transition as seamless as possible.
To make an appointment, please call 720-777-8628.
Providers can fax referrals to 720-777-7977.
- Cure HHT is a nonprofit organization focused on finding a cure for HHT while saving lives and improving the well-being of individuals and families affected by HHT. They fund research, educate families and physicians and advocate for and support those with HHT.
- The National Organization for Rare Disorders is a patient advocacy organization dedicated to individuals with rare diseases that provides education, advocacy, research and patient services.
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