1. Department of Echocardiography, Royal Brompton Hospital, Part of Guy’s and St Thomas’ NHS Foundation Trust, Sydney Street, Chelsea, London SW3 6NP, UK
2. Echocardiography Core Laboratory, Heart and Vascular Center, Semmelweis University, 68, Varosmajor Str., Budapest H-1122, Hungary
3. National Heart Lung Institute, Imperial College of London, Guy Scadding Building, Dovehouse St, Chelsea, London SW3 6LY, UK