Ventricular tachycardia esmolol

In the first 2 weeks post-MI, caution is advised and careful dose titration is especially important, particularly in patients with markedly impaired ventricular function. Intraoperative and postoperative tachycardia and hypertension Do not use esmolol as the treatment for hypertension in patients in whom the increased blood pressure is primarily caused by the vasoconstriction associated with hypothermia. Renal/Hepatic function impairment Use with caution. 

Class II drugs are the p-adrenoceptor antagonists that suppress the sympathetic modulation of the heart action. They are used in the therapy of sinus tachycardia, supraventricular paroxysmal tachycardia and ventricular extra-systoles. Because of its rapid onset and short duration of action, esmolol is the preferred drug in this class for intra-operative use. 

Endogenous norepinephrine stimulates cardiac beta receptors. Receptor-linked cAMP-dependent protein kinases phosphorylate calcium channels to increase intracellular calcium. Elevated intracellular calcium increases conduction velocity (phase 0) and decreases the threshold potential in normal SA and AV node cells (see Figure 12.13). Beta blockers slow spontaneous conduction velocity in the SA node by approximately 10-20 percent. In addition, beta blockers can slow conduction velocity while increasing the refractory period of the AV node. These effects control the ventricular rate in atrial fibrillation or flutter and terminate paroxysmal supraventricular tachycardias. They are also safer, although somewhat less effective, than other drugs for suppression of premature ventricular complexes (PVCs). Drugs in this class approved by the FDA for treatment of various arrhythmias include propranolol, acebutolol, and esmolol. Problems with the beta blockers include drowsiness, fatigue, impotence, and depressed ventricular performance. 

Class IB drugs act primarily on ventricular muscle and, in the case of lidocaine, concen- j trate in ischemic tissues. Adenosine is indicated for SVTs and nodal tachycardias. The primary actions of both beta blockers (esmolol) and CCBs (diltiazem) are at the AV node— they are not particularly effective in ventricular arrhythmias. Flecainide, a class IC drug, has been implicated in sudden deaths post-MI. 

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