Patients with in-situ metallic coils and Amplatzer vascular plugs used to treat pulmonary arteriovenous malformations since 1984 can safely undergo magnetic resonance imaging

Hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait and caused by loss-of-function pathogenic variants in genes encoding proteins of the BMP signalling pathway. Up to 90% of disease-causal variants are observed in ENG and ACVRL1, with SMAD4 and GDF2 less frequently responsible for HHT. In adults, the most frequent HHT manifestations relate to iron deficiency and anaemia owing to recurrent epistaxis (nosebleeds) or bleeding from gastrointestinal telangiectases. Arteriovenous malformations (AVMs) in the lungs, liver and the central nervous system cause additional major complications and often complex symptoms, primarily due to vascular shunting, which is right-to-left through pulmonary AVMs (causing ischaemic stroke or cerebral abscess) and left-to-right through systemic AVMs (causing high cardiac output). Children usually experience isolated epistaxis; in rare cases, childhood complications occur from large AVMs in the lungs or central nervous system. Management goals encompass control of epistaxis and intestinal bleeding from telangiectases, screening for and treatment of iron deficiency (with or without anaemia) and AVMs, genetic counselling and evaluation of at-risk family members. Novel therapeutics, such as systemic antiangiogenic therapies, are actively being investigated. Although HHT is associated with increased morbidity, the appropriate screening and treatment of visceral AVMs, and the effective management of bleeding and anaemia, improves quality of life and overall survival.

Ischemic Stroke and Pulmonary Arteriovenous Malformations: A Review

The potential of covert pulmonary arteriovenous malformations (PAVMs) to cause early onset, preventable ischemic strokes is not well known to neurologists. This is evident by their lack of mention in serial American Heart Association/American Stroke Association (AHA/ASA) Guidelines and the single case report biased literature of recent years. We performed PubMed and Cochrane database searches for major studies on ischemic stroke and PAVMs published from January 1, 1974, through April 3, 2021. This identified 24 major observational studies, 3 societal guidelines, 1 nationwide analysis, 3 systematic reviews, 21 other review/opinion articles, and 18 recent (2017-2021) case reports/series that were synthesized. Key points are that patients with PAVMs have ischemic stroke a decade earlier than routine stroke, losing 9 extra healthy life-years per patient in the recent US nationwide analysis (2005-2014). Large-scale thoracic CT screens of the general population in Japan estimate PAVM prevalence to be 38/100,000 (95% confidence interval 18-76), with ischemic stroke rates exceeding 10% across PAVM series dating back to the 1950s, with most PAVMs remaining undiagnosed until the time of clinical stroke. Notably, the rate of PAVM diagnoses doubled in US ischemic stroke hospitalizations between 2005 and 2014. The burden of silent cerebral infarction approximates to twice that of clinical stroke. More than 80% of patients have underlying hereditary hemorrhagic telangiectasia. The predominant stroke mechanism is paradoxical embolization of platelet-rich emboli, with iron deficiency emerging as a modifiable risk factor. PAVM-related ischemic strokes may be cortical or subcortical, but very rarely cause proximal large vessel occlusions. Single antiplatelet therapy may be effective for secondary stroke prophylaxis, with dual antiplatelet or anticoagulation therapy requiring nuanced risk-benefit analysis given their risk of aggravating iron deficiency. This review summarizes the ischemic stroke burden from PAVMs, the implicative pathophysiology, and relevant diagnostic and treatment overviews to facilitate future incorporation into AHA/ASA guidelines.

Approach to Pulmonary Arteriovenous Malformations: A Comprehensive Update

Pulmonary arteriovenous malformations (PAVMs) are abnormal direct vascular communications between pulmonary arteries and veins which create high-flow right-to-left shunts. They are most frequently congenital, usually in the setting of hereditary hemorrhagic telangiectasia (HHT). PAVMs may be asymptomatic or present with a wide variety of clinical manifestations such as dyspnea, hypoxemia, or chest pain. Even when asymptomatic, presence of PAVMs increases patients' risk of serious, potentially preventable complications including stroke or brain abscess. Transcatheter embolotherapy is considered the gold standard for treatment of PAVMs. Though previous guidelines have been published regarding the management of PAVMs, several aspects of PAVM screening and management remain debated among the experts, suggesting the need for thorough reexamination of the current literature. The authors of this review present an updated approach to the diagnostic workup and management of PAVMs, with an emphasis on areas of controversy, based on the latest literature and our institutional experience.