Acknowledgement
We wish to express our gratitude to the nurses and staff at the Department of Cardiothoracic and Vascular Surgery and the Department of Radiology, Örebro University Hospital. Special thanks to the research staff; Kerstin Bergström, Catarina Gerdevåg, Lenore Haugland and Lennart Johannesson for their thorough collection of data and kind care of the patients.