INAPPROPRIATE SINUS TACHYCARDIA - EVALUATION AND THERAPY

Inappropriate sinus tachycardia is an ill-defined clinical syndrome ch aracterized by an increased resting heart rate accompanied by an exagg erated response to exercise or stress. It is not associated with under lying structural heart disease, The mechanism may involve a primary ab normality of the sinus node demonstrating enhanced automaticity or, al ternatively, a primary autonomic disturbance with increase sympathetic activity and enhanced sinus node beta-adrenergic sensitivity, The dia gnosis of inappropriate sinus tachycardia is one of exclusion, It is m ost common in young females, with a disproportionate number employed i n the health care field, Autonomic and electrophysiologic testing may be required in selected individuals to clarify the mechanism and rule out sinus node reentry or right atrial tachycardia. Therapy of inappro priate sinus tachycardia is empiric, Pharmacologic approaches include beta blockers or verapamil. Radiofrequency catheter ablation of the su perior portion of the sinus node shows promise as a useful alternative in patients with refractory symptoms.