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For further information, see CMDT Part 40-24: Hereditary Hemorrhagic Telangiectasia

Key Features

  • An autosomal dominant disorder of development of the vasculature

  • Recurrent epistaxis

  • Mucocutaneous telangiectases

  • Visceral arteriovenous malformations (AVMs) (especially lung, liver, brain, bowel)

Clinical Findings

  • Epistaxis may begin in childhood or later in adolescence

  • Punctate telangiectases of the lips, tongue, fingers, and skin generally appear in later childhood and adolescence

  • AVMs can occur at any age in the brain, lungs, and liver

  • Bleeding from the gastrointestinal tract

    • Due to mucosal vascular malformations

    • Usually not a problem until mid-adult years or later

  • Pulmonary AVMs can cause

    • Hypoxemia (with peripheral cyanosis, dyspnea, and clubbing)

    • Right-to-left shunting (with embolic stroke or brain abscess)

  • The criteria for diagnosis require presence of three of the following four features:

    • Recurrent epistaxis

    • Visceral AVMs

    • Mucocutaneous telangiectases

    • Being the near relative of a clearly affected individual

  • Analysis of pathogenic variants can be used for presymptomatic diagnosis or exclusion of the worry of HHT


  • Contrast MRI of the brain should be obtained in all patients in whom HHT is suspected

  • Contrast echocardiogram

    • Detects most pulmonary AVMs when "bubbles" appear on the left side of the heart after 3–6 cardiac cycles

    • When findings are abnormal, obtain a high-resolution CT angiogram to localize pulmonary AVMs

  • MR or CT arteriography detects AVMs

  • Molecular analysis used to identify three genes that can cause HHT:

    • ENG

    • ALK1

    • SMAD4

  • Prenatal diagnosis through pathogenic variant detection is possible


  • Embolization is indicated for patients who have AVMs with a feeding artery of 2 mm diameter or greater

  • Embolization of pulmonary AVMs with wire coils or other occlusive devices reduces the risk of stroke and brain abscess

  • Treatment of brain AVMs reduces the risk of hemorrhagic stroke

  • All patients with HHT with evidence of a pulmonary shunt should practice routine endocarditis prophylaxis

  • All intravenous lines (except those for transfusion of red blood cells and radiographic contrast) should have an air-filter to prevent embolization of an air bubble

  • After successful embolization of all treatable pulmonary AVMs, the CT angiogram should be repeated in 6 months and 3 years

  • A person with a negative contrast echocardiogram should have the test repeated every 5 years

  • Any person with a pulmonary AVM, even an embolized one, should utilize routine endocarditis prophylaxis

  • Anti-estrogenic agents (eg, tamoxifen), thalidomide, or anti-vascular endothelial growth factor agents (eg, bevacizumab) may reduce epistaxis and gastrointestinal bleeding and improve hepatic shunting

  • However, two randomized, controlled clinical trials of intranasal bevacizumab therapy failed to show an improvement in epistaxis

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