Treatment should be offered to all people with a particular rare lung condition, regardless of whether or not they show symptoms of it, say researchers and doctors behind a new study published today.
The research, published online in the journal Thorax, suggests that all patients with abnormal blood vessels in their lungs known as pulmonary arteriovenous malformations (‘pulmonary AVMs’) might benefit from potentially life-saving treatment to block off the malformed blood vessels.
About 4,000 people in the UK are estimated to have pulmonary AVMs. As many as one in three of them will have a stroke or brain abscess by the age of 65, according to the new research.
Until now, treatment has only been available for small numbers of patients in the UK, because its effectiveness at reducing stroke was not proven and it was widely considered that only those already unwell could benefit from it.
The new study is the first to show that treatment lowers the risk of stroke. The authors - researchers and doctors from Imperial College London and Imperial College Healthcare NHS Trust - believe it is important that treatment is offered to all patients and not just to those who are obviously unwell.
The study reveals that seemingly healthy patients, with one or two pulmonary AVMs, have essentially the same risk of stroke as patients who are obviously unwell and have a number of large pulmonary AVMs.
“Our statistical analysis has shown that it doesn’t matter how sick someone is – a pulmonary AVM patient who is fit and well has the same stroke risk as someone who is on oxygen,” said Dr Claire Shovlin, from the National Heart and Lung Institute at Imperial College and lead author of the study.
Pulmonary AVMs are strongly linked to a genetic condition called Hereditary Haemorrhagic Telgangiectasia (HHT), which affects around 1 in 5,000 people in the UK. Most people with HHT are well and are unaware that they have the condition until it is diagnosed in a family member.
The authors of the new study call for screening for pulmonary AVMs to be given to all those with HHT. They say that doctors must not be complacent about the wellbeing of people with HHT just because they appear to be healthy.
“In other parts of the world, it is recommended that people with HHT should be screened for pulmonary AVMs and offered treatment for them. At the moment, relatively few individuals in the UK receive this sort of management,” added Dr Shovlin.
Pulmonary AVMs are a serious risk to patients because the enlarged blood vessels do not do their job of filtering out small clots or infected material circulating in the blood, thus allowing this material to pass into the brain, potentially causing stroke (clots), or brain abscess (infected material).
Pulmonary AVMs can be treated by a procedure known as embolisation, which is performed under local anaesthesia. The new study shows that this procedure is highly effective at preventing stroke in pulmonary AVM patients. All procedures in the study were carried out by Dr James Jackson, an interventional radiologist at Hammersmith Hospital, which is part of Imperial College Healthcare NHS Trust. Dr Jackson is one of the authors of the new research.
For the pulmonary AVM embolisation, the radiologist passes a fine tube through a blood vessel in the top of the leg and then introduces small metallic coils into the malformed blood vessels. The coils block off the blood supply to the malformed blood vessels and force the blood to flow through healthy blood vessels instead, ensuring that the blood is properly filtered.
“We have shown that healthy individuals with pulmonary AVMs may benefit not only from embolisation, but also from other preventative measures, including improving dental hygiene,” said Dr Shovlin.
Improved dental hygiene is important as bacteria from the mouth enter the bloodstream and can pass through pulmonary AVMs and enter the brain.
The cohort study analysed the medical histories of 219 pulmonary AVM patients seen by Dr Shovlin at Hammersmith Hospital from 1999 to 2005. Researchers looked at a huge range of data about the extent of their condition and their general level of health, including the size and number of malformed blood vessels in the lungs, oxygen levels, blood pressure and smoking history. They then compared the data for those patients who had suffered stroke or brain abscess and those who had not.
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This study was funded by the Margaret Straker HHT Memorial Fund and donations by families and friends of British HHT patients.
Notes to editors:
1. “Primary determinants of ischaemic stroke / brain abscess risks are independent of severity of pulmonary arteriovenous malformations in HHT” Thorax, 2 November 2007
Claire L Shovlin(1)(2), James E Jackson(2), Kathleen B Bamford(1)(2), I Harri Jenkins(2), Andrea R Benjamin(2), Hatem Ramadan(2), Elena Kulinskaya(1)
(1) Imperial College London (2) Imperial College Healthcare NHS Trust
This paper is available online at http://thorax.bmj.com/
2. Dr Claire Shovlin is Senior Lecturer in Respiratory Medicine at Imperial College London and Honorary Consultant in Respiratory Medicine at Imperial College NHS Trust (Hammersmith Hospital) in West London. She has run the medical HHT service at Hammersmith Hospital since 1999.
3. About HHT
Hereditary haemorrhagic telangiectasia (HHT) is a genetic condition that affects around 1 in 5,000 people in the UK. It is seen in both sexes and across all racial and ethnic groups. Each child of a patient with HHT has a 50 per cent chance of having HHT. Most sufferers remain perfectly healthy and many are unaware that they even have it – it is often only identified when one member of a family becomes unwell and other members are then checked for the condition. Only about half of people with HHT will develop pulmonary arteriovenous malformations (PAVMs), which are associated with a higher risk of stroke or brain abscess. Symptoms of HHT include: spontaneous and recurrent nosebleeds (though these are common in all children, so more suggestive in adulthood); multiple blood spots (telangiectasia) at sites including the lips, fingertips or inside the mouth; internal telangiectasia or arteriovenous malformations; and a family history of HHT.
An Information sheet on HHT is available through the Press Office.
4. HHT treatment at Hammersmith Hospital
Hammersmith Hospital has long been a centre of excellence in caring for patients with HHT and PAVMs. Professor David Allison, now retired, performed the UK’s first PAVM embolisation procedure at Hammersmith in 1983, and Dr James Jackson has performed all PAVM embolisations for approximately 20 years.
5. About Imperial College Healthcare NHS Trust
Hammersmith Hospital is part of Imperial College Healthcare NHS Trust, the UK’s first Academic Health Science Centre (AHSC) and largest NHS trust. An AHSC has integrated management across the Faculty of Medicine and the hospitals, and fuses biomedical research with patient care and medical training in a way never seen before in the UK, but hugely successful elsewhere – for example at Johns Hopkins Hospital in Baltimore, ranked America’s best hospital for the last 17 years by US News & World report. The AHSC was formed on 1 October 2007 by the merger of The Hammersmith Hospitals NHS Trust and St Mary’s NHS Trust in partnership with Imperial College London. The five hospitals in the Trust are: Charing Cross; Hammersmith; Queen Charlotte’s & Chelsea; St Mary’s, Paddington; and the Western Eye Hospital.
6. About Imperial College London
Rated as the world's ninth best university in the 2006 Times Higher Education Supplement University Rankings, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 11,500 students and 6,000 staff of the highest international quality.
Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
With 66 Fellows of the Royal Society among our current academic staff and distinguished past members of the College including 14 Nobel Laureates and two Fields Medallists, Imperial's contribution to society has been immense. Inventions and innovations include the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of our research for the benefit of all continues today with current focuses including interdisciplinary collaborations to tackle climate change and mathematical modelling to predict and control the spread of infectious diseases.
The College's 100 years of living science will be celebrated throughout 2007 with a range of events to mark the Centenary of the signing of Imperial's founding charter on 8 July 1907. Website: www.imperial.ac.uk
Journal
Thorax