Pharmacologic Blockade of the Left Stellate Ganglion Using a Drug-Reservoir-Pump System

Patients suffering from the long QT syndrome (LQTS) are threatened by sudden arrhythmic cardiac death. This hereditary disease is characterized by prolongation of QTc interval ^ 440 ms and stress-induced syncopes. Minor characteristics are: congenital deafness, alternating T wave, bradycardia in children, and repolarization disturbances.

The observation of stress-induced syncopes suggests that increased sympathetic activity in patients with LQTS may play an important role for the initiation of cardiac tachyar­rhythmias. Experimental studies have shown that an imbal­ance of sympathetic cardiac innervation with predominance of the left stellate ganglion results in QTc prolongation and ventricular tachyarrhythmias. This was the rationale to use p-blocking agents as the therapy of choice (ie, propranolol 2 to 4 mg/kg of body weight daily). If this drug has not proven to be effective in suppressing ventricular tachyar­rhythmias, propranolol may be combined with phenytoin (2.0 to 2.5 mg/kg of body weight daily). Administration of this medication led to a decrease of mortality in LQTS patients from well over 70 percent to approximately 7 percent over a five-year period. Nevertheless, medical therapy (propranolol + phenytoin) may fail in some cases. Therefore, operative left ganglion stellectomy was intro­duced as a new therapeutic approach to patients who suffer from syncopes despite oral medication. However, controver­sial results on the effects of left ganglion stellectomy were reported. Following left ganglion stellectomy, bradycardia and Horner’s syndrome were observed. Despite surgery some patients continued to have recurrent tachyarrhythmic episodes and syncopes. Electrical therapeutic approaches are of limited value, because either they are ineffective (ventricular overdrive stimulation) or they are not widely available (automatic implantable cardioverter-defibrillator). We therefore introduced a new therapeutic approach to patients with LQTS with tachyarrhythmias refractory to oral medical therapy. viagra plus


Category: Drug

Tags: Drug-Reservoir-Pump System, Pharmacologic Blockade

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