Intrapericardial beta-adrenergic blockade with esmolol exerts a potent antitachycardic effect without depressing contractility

Hyperadrenergic states of various etiologies can contribute to tachycardias . Systemic beta -adrenergic blockade suppresses sinus tachycardia but may a dversely affect arterial blood pressure and contractility, because the drug gains access to myocardial cells as well as to the sinoatrial node. We exa mined whether intrapericardial beta -adrenergic blockade with esmolol could suppress tachycardia without reducing contractility as a result of limited drug diffusion, which would be sufficient to penetrate the superficial sin oatrial node but not the deeper myocardial layers. In five anesthetized pig s, we provoked a reflex heart rate increase of 50 beats/min with hemorrhage . The rapidly acting beta -adrenergic blocking agent esmolol (1 mg/kg) was administered intrapericardially using a new percutaneous transatrial access method and a catheter system that can be rapidly and safely introduced. Es molol equivalently suppressed hemorrhage-induced sinus tachycardia when adm inistered intrapericardially (from 192 to 158 beats/min at 5 min, p < 0.05) or intravenously (from 177 to 151 beats/min at 1 min, p < 0.05). The antit achycardic effect of intrapericardial esmolol was prolonged compared with i ntravenous esmolol (10 min vs. 3 min, p < 0.05). Intrapericardial esmolol d id not affect blood pressure or left ventricular dP/dt max, an index of con tractility, whereas intravenous esmolol decreased blood pressure at 1 min f or 2 min (p < 0.05) and simultaneously decreased left ventricular dP/dt max at 1 min for < 2 min (p < 0.05). Intrapericardial esmolol suppresses adren ergically induced sinus tachycardia without decreasing contractility or blo od pressure. The transatrial approach for intrapericardial delivery of cert ain beta -adrenergic blocking agents could be employed to control tachycard ias in emergency care and surgical settings in patients with impaired cardi ac contractility and propensity to hypotension.