Associations Between Two Seemingly “Contradictory” Diseases: Hereditary Hemorrhagic Telangiectasia and Pulmonary Hypertension

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disorder characterized by mucocutaneous telangiectases and arteriovenous malformations (AVMs) predominantly in the liver, lung and brain. Pulmonary hypertension (PH) is a devastating disease of the pulmonary vasculature, which could lead to an increase in pulmonary vascular resistance and eventually cause right heart failure or death. Early epidemiological studies suggested that PH is a rare complication of HHT, however, accumulated evidences have showed that the prevalence of PH in HHT is evaluated up to 74 %. Post-capillary PH is the most common type of PH in HHT, which most often results from hepatic arteriovenous malformations due to a high cardiac output state. Another kind of HHT is less frequent and associated with genetic mutations in ENG or ACVRL1, those patients are more likely to develope into precapillary pulmonary arterial hypertension. PH is associated with a higher mortality rate and worse prognosis, which largely affects the overall life-expectation among those HHT patients. However, ENG and ACVRL1 mutations can only explain the onset of HHT and arteriovenous malformations, revealing the precise mechanisms of the co-occurrence of both diseases deserve further scientific attentions. Our review aims to illustrate the epidemiology, clinical features, molecular biological basis, pathological characteristics and potential treatment options for these two close associated but seemingly “contradictory” diseases