Early administration of calcium sensitizer in cardiac surgery

Objective: The number of patients with an unfavorable risk profile is increasing. Calcium sensitizers improve systolic function without increase of myocardial oxygen-consumption or impairment of diastolic function. As not yet accredited in Germany, but recommended for therapy of LCOS, Levosimemdan (LS) is most frequently administered as ultimo ratio when catecholamines and IABP fail-often too late to avert lethal outcome. Our study focused on the question if the point of time of administration of LS in cardiac surgery has an impact on postoperative course.

Methods: Experimental interleukin-6 induced LCOS-model to study contractile response of isolated right atrial trabeculae of CABG-patients to LS-therapy in dependence of point of administration-time. Experiments were carried out by force-clamping method under stretching to optimal fiber-length, at 37 °C. Isometric force was measured under electric stimulation (1 Hz, 4 – 6 Volt above threshold). Study groups differed in time point of LS-administration (10^-7 M)-before (group A; n = 9) and after (group B; n = 9) perfusion with Interleukin-6 (IL-6; 112 pg).

Statistical analysis was performed by comparison of mean values of isometric force by Friedmann Test. Statistical significance was assumed when p-value was < 0.05.

Results: LS-administration before experimentally induced reduction of contractility by IL-6 led to increase of isometric force to 138.3 ± 17.66%, reduced to 127.25 ± 17.2% by following IL-administration. Force reached 99.9% after wash-out-period. Initial IL-6-perfusion showed a decrease of isometric force to 69.2 ± 6.0%. After addition of LS, an increase to 128 ± 21.6% and after washing out with KHS to 77.9%± 8.6% took place.

Conclusion: LS-administration before the onset of experimentally induced negative inotropic effect can attenuate "contractile damage". Pre-/intraoperative LS-pretreatment might help to prevent/soften LCOS and should be considered for patients at risk.