1. From Royal Brompton Hospital (M.J.M.), London, United Kingdom; Royal Sussex County Hospital (D.H.-S.), Brighton, United Kingdom; University Hospital (J.V.D.G.), Birmingham, United Kingdom; Glenfield Hospital (C.D.), Leicester, United Kingdom; Western Infirmary (W.S.H.), Glasgow, United Kingdom; Cardiothoracic Centre (W.L.M.), Liverpool, United Kingdom; and Georg-August University (C.J.), Goettingen, Germany.