Circulation, Vol 56, 720-726, Copyright © 1977 by American Heart Association
MS Dhatt, M Akhtar, P Reddy, JA Gomes, SH Lau, AR Caracta and AN Damato
The phenomenon of macrore-entry (Re) within the His-Purkinje system (HPS)
was consistently observed in 10 of 19 patients during retrograde refractory
period studies. Effects of intravenous infusion of diphenylhydantoin (DPH)
on Re were studied in these 10 patients 10 minutes after completion of
infusion (mean plasma level equal to 17.0 microgram/ml). Diphenylhydantoin
modified determinants of Re in seven patients (group I) and abolished Re in
the remaining three patients (group II). In group I, DPH shortened the
critical V1 V2 from 310.0 +/- 30.5 to 292.9 +/- 25.6 msec (P less than
0.025) and critical V2 H2 intervals for Re from 201.4 +/- 18.4 to 185.0 +/-
13.8 msec (P greater than 0.05). In group II, DPH abolished Re in two of
three patients by precluding attainment of critical V2 H2 intervals whereas
Re was abolished in the remaining one patient despite attainment of
critical V2 H2 intervals (vs control). For both groups, DPH significantly
shortened functional and effective refractory periods of the HPS (P less
than 0.001 and less than 0.01, respectively) without significantly
affecting the effective refractory period of the ventricular muscle.
Diphenylhydantoin either completely abolished or significantly shortened
the retrograde gap zones in the HPS. It is concluded that diphenylhydantoin
significantly shortens His-Purkinje system refractoriness, abolishing Re in
the patients with higher degree of improvement in refractoriness.
ARTICLES
Modification and abolition of re-entry within the His-Purkinje system in man by diphenylhydantoin