Hereditary Hemorrhagic Telangiectasia (HHT) patients have an abnormality in their blood vessels that causes them to bleed easily, even spontaneously. Most blood vessels in the body of someone with HHT are normal. However, a small percentage of the blood vessels in a person with HHT have a specific type of malformation.
This can result in rupture and bleeding. When this involves small blood vessels, it is called a telangiectasia. When larger blood vessels are formed incorrectly and get tangled, it is called an arteriovenous malformation (medical abbreviation: AVM). The location of blood vessel abnormalities in the body determines what kind of symptoms patients will have.
Signs and Symptoms of HHT
HHT can affect the nose and cause heavy nosebleeds (the medical term for nosebleeds is epistaxis). While nosebleeds are not necessarily life-threatening, there is a quality of life issue because nosebleeds can be spontaneous, happening at any time and for no apparent reason. Nosebleeds are the most common symptom of HHT.
About 95 percent of people with HHT have recurring nosebleeds by the time they reach middle age. The nosebleeds generally start about age 12 but they can begin as early as infancy or as late as adulthood. Some patients experience heavy nosebleeds only a few times a year while for others, it is a daily occurrence. The nosebleeds can last anywhere from a few seconds, up to several hours. The amount of blood lost may be a few drops, or enough to cause anemia (low blood count). Most people with HHT fall somewhere in between these two extremes.
Skin Arteriovenous Malformation
Rupture and bleeding in the skin of the hands, face and mouth are also found in about 95 percent of people who have hereditary hemorrhagic telangiectasia. While it usually doesn’t become apparent until the patient is 30 or 40 years old, HHT appears as small red to purplish spots. These skin arteriovenous malformations can bleed but it is less likely than those in the nose.
Malformation in the Brain, Lungs or GI Tract
HHT can be fatal if the AVM is in the patient’s brain, lungs or GI tract (stomach and intestines). AVMs in the GI tract do not cause pain or discomfort. Symptoms of GI bleeding are black or bloody stools and/or anemia. The anemia (low blood count) can then cause fatigue, shortness of breath, chest pain or dizziness.
Approximately 15 percent of HHT patients develop AVMs in the lungs. These pulmonary AVMs are at risk for rupture, which can lead to life-threatening bleeding. This is especially true during pregnancy because blood pressure and blood volume are higher. Likewise, those diagnosed with pulmonary AVMs are advised not to SCUBA dive. In addition, there is a risk for stroke or brain abscess (bacterial brain infection), which can be life threatening or disabling. To prevent brain abscesses, it is recommended that patients diagnosed with pulmonary AVMs take antibiotics prior to dental cleaning and some other procedures.
Brain AVMs are less common and are found in only about 5-20 percent of people with HHT. In most cases, these can be treated successfully but they can be life threatening or disabling if they bleed. Since there are no warning symptoms prior to causing a brain hemorrhage, testing for them is recommended for all people who are diagnosed with HHT.
HHT Symptoms Vary
Symptoms of HHT vary greatly, even within the same family. For example, a parent may have horrible nosebleeds, but no AVM in an internal organ. Yet, the child may have a nosebleed only rarely, yet have AVMs in one or more internal organs. There is no way to predict how likely someone is to have one of the hidden, internal AVMs based on how many nosebleeds or skin AVMs they have.
Who’s Most at Risk?
HHT is not an environmentally driven disease. Rather, it is based on genetics. HHT typically manifests itself in late adolescence into early adulthood. However, children can have HHT and the symptoms as well. Some patients don’t show symptoms until the age of 40. HHT does not affect any particular racial or ethnic group.