Intracardiac stimulation for the diagnosis of arrhythmia.

Intracardiac stimulation (IS) has been widely used as the diagnostic method for various kinds of arrhythmias. Our results as to IS are as follows: 1) Since sinus recovery time (SNRT) closely correlated with basic cycle length (BCL) in 71 normal cases (r = 0.82, p less than 0.001), upper range of SNRT in normal was expressed as SNRT = 1.4BCL + 451 msec. 2) Paroxysmal supraventricular tachycardia (PSVT) induced by IS was fairly similar to the spontaneous PSVT (107 cases). Therefore, IS can be used to confirm the diagnosis of PSVT and also to evaluate the effectiveness of antiarrhythmic agents on PSVT. 3) Although induction or termination of ventricular tachycardia by IS may be useful in a general sense, dangerous tachyarrhythmias were sometimes provoked, indicating this test should be carried out under the utmost care.