Hereditary hemorrhagic telangiectasia and pulmonary arteriovenous malformations: clinical aspects

Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder of blood vessel formation characterized by mucocutaneous and visceral vascular malformations resulting in direct communication between arterioles and venules without intervening capillary beds (1). These malformations lead to variable clinical manifestations that depend on where they occur and to what extent. Certain tissues are affected more often than others, but virtually any tissue can be involved. Recurrent epistaxis from nasal telangiectasias is present in nearly all patients by the age of 40 (2,3). Gastrointestinal telangiectasias and hepatic and cerebral vascular malformations are seen with varying frequency. The diagnosis of HHT is based on clinical criteria (4) whereby the presence of at least three of the following four criteria establishes a definite diagnosis of HHT: recurrent epistaxis, multiple characteristic telangiectasias, visceral vascular malformations, and a first-degree relative meeting diagnostic criteria for HHT (Table 1). Pulmonary arteriovenous malformations (PAVMs) are the most common pulmonary manifestation of HHT and only rarely occur sporadically in patients without HHT. It is essential, therefore, that physicians who provide care to patients with PAVMs be aware of the clinical manifestations of HHT in general and of HHT-related PAVMs in particular