1. Department of Cardiothoracic Surgery; Liverpool Heart and Chest Hospital; Liverpool UK
2. Queen Elizabeth Hospital, University Hospital Birmingham; Birmingham UK
3. Department of Cardiothoracic Surgery; Nothern General Hospital; Sheffield UK
4. Department of Cardiothoracic Surgery; Nottingham City Hospital; Nottingham UK
5. Department of Cardiac Surgery; Glenfield Hospital; Leicester UK
6. Department of Cardiac Surgery; Trent Cardiac Centre, Nottingham City Hospital; Nottingham UK
7. Department of Cardiothoracic Surgery; The Liverpool Heart and Chest Hospital; Liverpool UK