The effect of the ultrashort beta-blocker esmolol on cardiac function recovery: an experimental study

This is an experimental work designed to determine, using the isolated perfused rat heart, the effect of the ultra-short acting beta-blocker esmolol on cardiac arrest and cardiac function recovery following esmolol withdrawal.

Changes in heart rate, coronary flow, diastolic pressure and the rate pressure product were evaluated on the isolated heart (Langendorff model). Esmolol concentrations of 125, 250, and 500 mg/l were tested. In another experiment using esmolol concentration of 250 mg/l, cardiac function recovery was assessed after 20- and 45-min arrest.

While concentrations of 250 and 500 mg/l are necessary to produce cardiac arrest, the concentration of 500 mg/l does not result in full cardiac function recovery following esmolol withdrawal. After the highest concentration of esmolol, coronary flow, heart rate and the rate-pressure product recovered to about 80, 70 and 60% of the initial control values, respectively. When comparing 20- and 45-min arrests we found cardiac function normalization occurs later after 45-min arrest.

The induction of cardiac arrest by esmolol is optimal at a concentration of 250 mg/l. A concentration of 125 mg/l does not result in cardiac arrest and produces bradycardia only, a concentration of 500 mg/l may be dangerous on account of persisting undesirable effects on the rat heart.