Hereditary Hemorrhagic Telangiectasia (Osler-Weber-Rendu disease):
Pathogenesis and Clinical Findings
Inherited or de novo mutation in the ACVRL1, ENG, or Smad4 genes
Abnormal signalling within the transforming growth factor ß (TGF-ß) pathway
Unclear mechanismsàInability of vascular mural cells to stabilize and remodel newly formed blood vessels
Excessive proliferation of endothelial cells and ensuing overgrowth of blood vessels
Authors: Tony Gu Reviewers: Brian Rankin Yan Yu* Laurie Parsons* * MD at time of publication
Formation of friable telangiectasias
(small dilated vessels apparent near the surface of skin or mucous membranes)
Formation of Arteriovenous malformations (AVMs):
Direct connection between arteries and veins without intervening capillary bed
Nasal telangiectasias
Epistaxis (nosebleeds)
Gastrointestinal telangiectasias
Gastrointestinal bleeding
Mucocutaneous telangiectasias
Cerebral AVMs
Hepatic AVMs
Left to right shunting of blood
Heart works harder to perfuse tissues
Heart failure
Pulmonary AVMs
Rupture
High flow left to right shunting of blood (the steal effect)
Cerebral ischemia
No oxygenation at capillaries
Hypoxemia
↑ erythropoietin production
Secondary polycythemia
No filtering from capillaries
Hemorrhage, shock, death
Venous emboli enter arteries (paradoxical embolism)
Stroke
Venous bacteria enter arteries
Cerebral abscess
Iron deficiency anemia
↓ serum iron is associated with ↑ coagulation factor VIII levels (mechanism unclear)
Venous thromboembolism
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published July 28, 2020 on www.thecalgaryguide.com