1. Department of Cardiology, Royal Brompton and Harefield NHS Foundation Trust, Sydney Street, London SW3 6NP, UK
2. Department of Cardiology, Doncaster and Bassetlaw Hospitals, NHS Foundation Trust, Thorne Road, Doncaster DN2 5LT, UK
3. Wellcome/EPSRC Centre for Interventional and Surgical Sciences (WEISS), UCL, Foley Street, London W1W 7TS, UK
4. Department of Pathology, Royal Brompton and Harefield NHS Foundation Trust, Sydney Street, London SW3 6NP, UK
5. National Heart and Lung Institute, Imperial College London, Guy Scadding Building, Dovehouse St, London SW3 6LY, UK
6. Department of Biomedical Engineering, Johns Hopkins University, Charles Street, Baltimore, MD 21218, USA