[1] Univ Thessaly, Dept Cardiothorac Surg, Unit Qual Improvement, Biopolis, Larisa 41110, Greece
[2] Univ Thessaly, Dept Cardiol, Biopolis, Larisa 41110, Greece
[3] Univ Thessaly, Dept Cardiothorac Surg, Biopolis, Larisa 41110, Greece
[4] Imperial Coll London, St Marys Hosp, Dept Surg & Canc, London W2 1NY, England
[5] Univ Thessaly, Dept Anesthesiol, Biopolis, Larisa 41110, Greece
[6] Natl & Kapodistrian Univ Athens, Fac Med, Dept Therapeut, Athens 10679, Greece