1. Cardiology Department, Sheffield Teaching Hospitals, Sheffield S5 7AU, UK
2. ENT Department, Tameside General Hospital, Ashton-Under-Lyne OL6 9RW, UK
3. Dermatology Department, Doncaster Royal Infirmary, Doncaster DN2 5LT, UK
4. Cardiothoracic Department, Sheffield Teaching Hospitals, Sheffield S5 7AU, UK