Beta-adrenergic blockade in the treatment of exercise-induced paroxysmal ventricular tachycardia.

PAROXYSMAL ventricular tachycardia of the type provoked by exertion or excitement is a rare condition well described by Wilson et al. in 1932.1 The circumstances under which paroxysms occur suggest that sympathetic stimuli are important in producing the arrhythmia. Responses to sympathetic stimuli have been classified by Ahlquist as either a-adrenergic or /3-adrenergic.2 Chronotropic and cardiac arrhythmic effects are in the latter group3 and blockade of f3-adrenergic responses is a rational approach to therapy. The /8-adrenergic blocking drug pronethalol (or nethalide) is effective in the treat-