Tachycardia control in septic shock with esmolol and ivabradine: A comparison on heart function

Persisting tachycardia is often observed in resuscitated septic shock patients, and it is an independent risk factor for increased mortality. Recently, several drugs, such as esmolol and ivabradine, have been proved to be beneficial in HR control, but their overall impact on cardiac functions needs further investigation. The aim of this study is to study the effects of the two drugs on heart function in a protocol of polymicrobial septic shock and resuscitation. Twelve pigs were divided into three experimental groups: the esmolol-treated group (n=4), the ivabradine-treated group (n=5) and the control group (n=3). Cardiac autonomic activity was estimated by heart rate variability (HRV) indices and baroreflex sensitivity (BRS). The Buckberg index was adopted to evaluate myocardial oxygenation efficiency. Septic shock induced a severe autonomic dysfunction and a lower cardiac efficiency, not resolved by fluids resuscitation. The administration of the drugs improved both the HRV and the BRS, but this favourable condition was preserved after noradrenaline administration only in the esmolol group. The interaction of esmolol with the autonomic system is beneficial in septic shock to restore an improved condition of HRV and control, while ivabradine is not as effective when administered in adjunction to noradrenaline.