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 and our Newletters updated for 2021 are provided below.   

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

2021 Summary information from our group is available in the following Research Support Items:

· 2020 PAVM and HHT Research Newsletter   
- PAVMs: MRI scans post embolisation; breathlessness, antibiotics and COVID
- HHT: severe anemia; blood thinners; COVID and VASCERN HHT links

· 2019 HHT Research Newsletter
- Introduction to VASCERN HHT, the European Reference Network dedicated to HHT chaired by Shovlin 2016- Brexit Dec 2020; cancer rates and HHT

· The Oxygen Train  
- An evidence based- model for the circulation, anemia and low oxygen levels

Earlier research newsletters covering additional topics have been updated for 2021 where the topics were not fully covered in later newsletters.  The key publications from this period are available here .  

· 2017 Research Newsletter ( 2021 update) 
- HHT and blood thinners, HHT nosebleeds and health benefits from HHT

· 2016 HHT Iron Research Newsletter (2021 update)
- Getting the iron balance right: Understanding requirements and sources, and risks of too little and too much iron

· 2015 HHT and PAVM Research Newsletter (2021 update)
- Anaemia; other effects of low iron levels; low oxygen levels; and exercise

· 2012 HHT Research Newsletter (2021 update) 
- Blood clots; blood clots and low iron levels; flying

· 2011 PAVM and HHT Research Newsletter (2021 update)
- Why PAVMs are important; HHT clinical diagnosis; pregnancy