[1] Linkoping Univ, Dept Med & Hlth Sci, Div Nursing Sci, Fac Hlth Sci, S-58185 Linkoping, Sweden
[2] Linkoping Univ Hosp, Dept Cardiothorac Surg, Cty Council Ostergotland, S-58185 Linkoping, Sweden
[3] Swedish Inst Hlth Sci, Lund, Sweden
[4] Linkoping Univ Hosp, Dept Cardiol, Cty Council Ostergotland, S-58185 Linkoping, Sweden