Effects of heparin on serum ionized calcium and haemodynamics during coronary artery surgery

Heparin has been reported to possess hypotensive and vasodilating properties when given in 3 mg/kg bolus injection. The haemodynamic effect has been thought to be related to an acute lowering of serum ionized calcium levels. The effects of heparin on haemodynamics and ionized calcium were compared with saline in 30 patients during coronary artery surgery before the commencement of cardiopulmonary bypass. There were no significant differences in haemodynamics or ionized calcium levels between heparin or saline during the observation period of 10 min. The results are at variance with some previous findings, and suggest that the hypotensive reaction occasionally seen after heparin is given is not mediated by the reduction of serum ionized calcium.