Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 40-23: Hereditary Hemorrhagic Telangiectasia + Key Features Download Section PDF Listen +++ ++ An autosomal dominant disorder of development of the vasculature Recurrent epistaxis Mucocutaneous telangiectases Visceral arteriovenous malformations (AVMs) (especially lung, liver, brain, bowel) + Clinical Findings Download Section PDF Listen +++ ++ 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 Mutation analysis can be used for presymptomatic diagnosis or exclusion of the worry of HHT + Diagnosis Download Section PDF Listen +++ ++ 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 mutation detection is possible + Treatment Download Section PDF Listen +++ ++ 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