Esmolol
Another group of drugs that are used in off-pump CABG, belongs to
β-adrenergic antagonists (β blockers) among them, Esmolol (ESM), by
reducing the extent of myocardial injury during ischemia and coronary
reperfusion. It is believed that the negative inotropic and chronotropic
effects of these drugs concomitantly reduce myocardial oxygen
consumption (MVO2) and decrease sympathetic tone, thereby exerting a
beneficial effect on the ischemic myocardium. However, most β blockers
are known for prolonged negative inotropic properties, which limits
their use during cardiac surgery (2 )(3 ).
Esmolol (ESM) belongs to the Β blocker drug group (ultra-short-acting β1
selective-adrenergic blocker). It presents a rapid action onset of 1-2
minutes in which it is quickly metabolized by red blood cell esterase;
its elimination half-life (T ½) is 9 -10 min. The rapid onset of action
of this agent and its short duration of effect is an advantage in the
perioperative period. The drug can be administered either as a bolus
injection or as a continuous intravenous infusion. It is commonly
administered in doses of 0,5mg/Kg and its effect stops within 10-20
minutes of discontinuing the infusion (7 ).
In clinical studies (following hemodynamic resuscitation) ESM
administration has shown a reductive effect of myocardial damage in the
context of acute ischemia. A hemodynamic benefit has also been accepted
by decreasing contractility, economizing cardiac work and decreasing
cardiac energetic costs with a consequent reduction in oxygen
consumption (MVO2) (8 ).At the cellular level,
these drugs reduce mitochondrial respiration and phosphorylase activity,
thus buffering the production of free radicals. Because hemodynamic
changes are common in laryngoscopy, lidocaine is often administered
intravenously 90 seconds before intubation in order to suppress
laryngeal reflexes, and ESM may be used to reduce heart rate and blood
pressure in response to post-laryngoscopy. ESM is an excellent option
for attenuation of cardiovascular responses to airway instrumentation
(9 ).