[1] Univ Zurich, Horten Ctr Patient Oriented Res & Knowledge Trans, Zurich, Switzerland
[2] Cty Hosp Freiburg, Dept Gen Surg, Freiburg Im Breisgau, Switzerland
[3] Triemli City Hosp, Dept Cardiac Surg, Zurich, Switzerland
[4] Univ Hosp Basel, Dept Cardiac Surg, Spitalstr 21, CH-4031 Basel, Switzerland