[1] Univ Hosp Wurzburg, Dept Cardiothorac & Thorac Vasc Surg, Wurzburg, Germany
[2] Univ Hosp Schleswig Holstein, Dept Cardiovasc Surg, Campus Kiel,Arnold Heller Str 3, D-24105 Kiel, Germany
[3] Univ Hosp Schleswig Holstein, Inst Med Informat & Stat, Campus Kiel, Kiel, Germany