Hereditary Hemorrhagic Telangiectasia and Arterio-Venous Malformations-From Diagnosis to Therapeutic Challenges

Hereditary hemorrhagic telangiectasia is a rare autosomal dominant vascular disease defined by the presence of mucosal and cutaneous telangiectasia and visceral arterio-venous malformations. The latter are abnormal capillary-free direct communications between the pulmonary and systemic circulations with the following consequences: arterial hypoxemia caused by right-to-left shunts; paradoxical embolism with transient ischemic attack or stroke and brain abscess caused by the absence of the normally filtering capillary bed; and hemoptysis or hemothorax due to the rupture of the thin-walled arterio-venous malformations (particularly during pregnancy). It is frequently underdiagnosed, commonly presenting as complications from shunting through arterio-venous malformations: dyspnea, chronic bleeding, or embolism. Arterio-venous malformations are present not only in the lungs, but can also be found in the liver, central nervous system (mainly in the brain), nasal mucosa, or the gastrointestinal tract. The first choice of therapy is embolization of the afferent arteries of the arterio-venous malformations, a minimally invasive procedure with a high efficacy, a low morbidity, and low mortality. Other therapeutic modalities are surgery (resection) or stereotactic radiosurgery (using radiation). Routine screening for arterio-venous malformations is indicated in patients diagnosed with this condition and can prevent severe complications such as acute hemorrhages, brain abscesses, or strokes. Clinicians should provide a long-term follow-up for patients with arterio-venous malformations, in an effort to detect their growth or reperfusion in case of previously treated malformations. In spite of two experts' consensuses, it still possesses multiple therapeutic challenges for physicians, as several aspects regarding the screening and management of arterio-venous malformations still remain controversial. Multidisciplinary teams are especially useful in complex cases.