What are the signs and symptoms of pulmonary AVMs in Osler-Weber-Rendu disease (OWRD) (hereditary hemorrhagic telangiectasia [HHT])?

Updated: Oct 06, 2020
  • Author: Klaus-Dieter Lessnau, MD, FCCP; Chief Editor: Vincent Lopez Rowe, MD  more...
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Answer

The majority of pulmonary AVMs occur as part of HHT, [44, 45] affecting approximately 50% of HHT patients. Pulmonary AVM, with right-to-left pulmonary shunting, is the major cause of transient ischemic attack, brain abscess, and ischemic stroke in HHT patients as a result of paradoxic embolization of bland or septic material into the cerebral vasculature. These symptoms may be either the first manifestation of pulmonary HHT involvement or the presenting symptoms of HHT itself. [6]

Small AVMs with shunting of less than 25% of pulmonary blood flow are asymptomatic in half of cases. These patients show no cyanosis but demonstrate dyspnea on exertion and easy fatigability. Larger AVMs, especially when multiple, may result in dyspnea, fatigue, cyanosis, clubbing, and polycythemia. [56] Such severe shunting, defined as more than 25% of pulmonary blood flow, is seen in 20% of cases.

A study published by Shovlin et al in 2014, which included 497 patients with computed tomography (CT)-proven pulmonary AVMs due to HHT, suggested that patients with compromised pulmonary capillary filtration due to pulmonary AVMs are at increased risk of ischemic stroke if they are iron-deficient and that mechanisms are likely to include enhanced aggregation of circulating platelets. [44]

Auscultation reveals a continuous thoracic bruit in half of patients with cyanosis. Cyanosis and clubbing are particularly associated with an increased risk of cerebral abscess and stroke. With pulmonary AVM, unlike hepatic AVM, increased cardiac output with high-output heart failure is unusual.


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