[1] Univ Calgary, Cumming Sch Med, Dept Cardiac Sci, Sect Cardiac Surg,Libin Cardiovasc Inst, Calgary, AB T2N 2N9, Canada
[2] Univ Alberta, Fac Med & Dent, Dept Anesthesiol & Pain Med, Edmonton, AB T6G 2R7, Canada
[3] Univ Calgary, Dept Physiol & Pharmacol, Calgary, AB T2N 1N4, Canada