Levosimendan has a prolonged antispasmodic effect in isolated human radial artery bypass grafts and inhibits thrombin-induced aggregation of human platelets in vitro

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Abstract in foreign language

We have shown that contractions of the human RA grafts are larger than those of the IMA grafts in vitro. This finding supports the higher incidence of severe vasospasm of RA during CABG. We have demonstrated that the 5-HT-induced contractions of human RA graft segments pre-incubated in 0.9% NaCl solution were stable for 120 minutes. Levosimendan, in a therapeutic concentration (0.16 μmol/L), had a prolonged effect (>90 minutes) on the 5-HT-induced tone of the human RA segment. Levosimendan also effectively decreased NA-induced contractions. The colloidal Biseko®solution is effective against both NA- and 5-HT-induced contractions in human RA graft segments. The effect of Biseko®solution on 5-HT-induced contractions lasts for only 45 minutes. The maximal contractile and vasodilating capacities as well as the endothelium-dependent relaxation of RA segments pre-incubated in levosimendan solution were comparable to controls, suggesting that the inodilator does not deteriorate the function of the graft. BKCachannels do not account for the prolonged effect of levosimendan in reducing contraction of RA graft segments. Therapeutic concentrations of levosimendan (≤0.2 μmol/L) reduced thrombin-induced platelet aggregation in vitro. The platelet inhibitory effect of levosimendan is markedly decreased by albumin and significantly enhanced upon increasing the time of pre-incubation. These findings may render the inodilator drug, levosimendan, effective in preventing the spasm of the RA and the thrombotic occlusion of the graft during the intraoperative phase of CABG.

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