Imperial College London

Professor Claire Shovlin

Faculty of MedicineNational Heart & Lung Institute

Professor of Practice (Clinical and Molecular Medicine)



c.shovlin Website




534Block L Hammersmith HospitalHammersmith Campus





Basic information is provided below.  A new website to deliver updated information is under development and the link will be posted here soon.    

HHT (hereditary haemorrhagic telangiectasia) is a genetic disorder that affects approximately 1 in 5,000 individuals. At present in the UK, most people with HHT are not diagnosed, though most will be aware that they, or family members, have frequent nosebleeds. HHT leads to the development of abnormal blood vessels. When present in the nose, and in the gut, they may bleed. Over long periods, chronic bleeding exhausts the body’s iron stores, and people may become anaemic. HHT also leads to the development of abnormal vessels called arteriovenous malformations (AVMs) in internal organs such as the lungs, liver and brain, and to other rarer complications.  

Pulmonary arteriovenous malformations (PAVMs) affect 50% of people with HHT, and also occur in people without HHT. To understand PAVMs, it is helpful to think how the heart pumps blood around the body.  When the blood returns to the heart, before it goes round the body a second time, it is ALL sent to the lungs to pick up oxygen and have waste removed.  If PAVMs are present, they are like a fast bypass and any blood passing through these vessels goes straight back to the heart .  This means blood is not processed properly leading to low oxygen levels (which are tolerated very well), and other complications.  There are steps people with PAVMs can take to improve their health, particularly regarding embolization treatments, pregnancy and dental care

If you are looking for our 2021 Survey, this is not yet open,  but the link will be available here in April 2021.

Pre 2018 Summary information from our group is available in the following:

· 2017 Newsletter     (nosebleeds, health benefits from HHT, and Survey)

· 2016 Newsletter PDF Acrobat Document(getting the iron balance right: requirements, sources, and
                                  risks of too little and too much iron)

· 2015 Newsletter PDF Acrobat Document(anaemia; other effects of low iron levels; low oxygen       
                                  levels; and exercise)

· The Oxygen Train   (a model for the circulation, anemia and low oxygen levels)

and earlier newsletters covering additional topics:

· 2014 Newsletter PDF Acrobat Document (why HHT causes anaemia; why noses bleed; taking blood
                                   thinners; and low cancer rates in HHT)

· 2012 Newsletter PDF Acrobat Document(blood clots; blood clots and low iron levels; flying)

· 2011 Newsletter     (clinical diagnosis; pregnancy; pulmonary AVM importance)

Key publications from the group are available here .