Shortening Of R-Pp Interval By Verapamil In Reciprocating Tachycardia

Abstract

T he R-P’ interval in reciprocating tachycardia represents the temporal relationship between ventricular depolarization and retrograde atrial depolarization. This interval, however, does not reflect the A-V nodal conduction sequences during such a tachycardia, but is merely the end result of these sequences. The Ibllowing case reflects a shortening ofthe R-P’ interval following the intravenous administration of verapamil. The electrocardiogram (Fig 1, all strips of standard lead 2) was recorded from a 55-year-old woman with recurrent attacks ofsupraventncular tachycardia. Strip A was recorded during the attack. The R-R intervals measured 0.34 second, representing a rate of176 beats per minute. The P’ waves ofretrograde atrial activation were superimposed upon, and deform the T waves. The R-P’ interval measured from the beginning of the QRS complex to the sharp nadir of the P’ wave-the initial deformity of the T wave-was 0.21 second.