HHT-related nosebleeds are caused by fragile telangiectases in the nose. Nosebleeds can begin at any age, but average age of onset is 12; by middle age, about 95% of patients with HHT have recurring nosebleeds. They are highly variable in frequency and severity.
Nosebleeds and/or GI bleeding can result in chronic anemia in at least one-third of HHT patients. Oral iron supplementation is usually sufficient to correct the anemia; occasionally, intravenous iron infusions or blood transfusions are required.
Nosebleed management includes lifestyle modifications including room humidification; topical salves; and when necessary, surgical intervention.
Pulmonary AVMs result in passage of blood directly from the pulmonary to the systemic circulation, without the filtering effect of lungs. This can result in ischemic stroke or brain abscess. Approximately 30-50% of HHT patients have one or more AVMs in the lungs.
Pulmonary AVMs are usually silent until a catastrophic event occurs.
Chest CT and/or contrast echocardiography (bubble study) are noninvasive and highly sensitive for detection of pulmonary AVMs. Treatment with angiography and embolization is safe and effective, and has been shown to reduce or abolish neurological risks.
If the bubble study is positive, a chest CT is performed to determine the anatomy of the AVM and suitability for embolization treatment.
Even if these tests are negative for pulmonary AVM, there may still be tiny AVMs present in the lung, which are too small to be detected. For this reason, it is recommended that all HHT patients receive antibiotic prophylaxis prior to dental procedures, and consult a physician prior to scuba diving.
Also known as a bubble study, a contrast echocardiogram involves injecting agitated saline into a peripheral IV, then using an ultrasound probe to monitor the heart chambers. Normally, the capillaries of the lung will filter these microbubbles out of the circulation; but if a pulmonary AVM is present, bubbles will be seen passing into the heart. The severity of the shunt can be graded based on the number of microbubbles seen.
A routine non-contrast chest CT scan can be performed in seconds, and is also highly sensitive for detection of pulmonary AVMs. This test does involve radiation exposure, however. Chest CT has the benefit of identifying other chest pathology, such as pulmonary hypertension
Vascular malformations in the brain are present in about 10% of HHT patients. Although most HHT-related cerebral AVMs will never bleed, a cerebral hemorrhage can be a life-changing or fatal event. Therefore, we recommend screening of all HHT patients for cerebral AVM.
A routine brain MRI is a noninvasive and highly accurate test to detect and characterize cerebral AVMs. This is usually performed early in life, as bleeding from brain AVMs can occur at any age.
Magnetic resonance imaging (MRI) of the brain is a very accurate and noninvasive test for cerebral AVMs. It allows cross-sectional imaging of the brain and the cerebral vessels with high resolution. No radiation is used. In adults and children over 2 years of age, a contrast agent called gadolinium is injected at the time of the scan to improve the sensitivity of the test. Imaging protocols vary, but at the minimum, brain MRI should be performed once in childhood (the earlier the better) and once upon reaching adulthood.
Telangiectases of the gastrointestinal tract are often present in HHT, and occur most commonly in the stomach and small intestine. These do not cause discomfort, but about 20-25% of HHT patients will develop symptoms of gastrointestinal bleeding, which can result in chronic anemia. In the absence of bleeding, these telangiectases are usually not treated.
Hepatic AVMs are common among HHT patients, but they are almost always clinically silent, and rarely cause complications. For this reason, screening for hepatic AVMs is usually not performed in asymptomatic patients. Hepatic AVMs can cause asymptomatic elevation in liver enzymes, which are of little clinical importance, but can result in unnecessary diagnostic tests. Liver biopsy should be avoided.
In rare cases, diffuse hepatic AVMs can result in heart or liver failure. These patients undergo intensive medical treatment, with liver transplantation considered for non-responders.