Changes in atrioventricular conduction properties with refractory-period modulation

Journal of Cardiovascular Pharmacology
K W HewettC L Case

Abstract

Dofetilide, clofilium, and risotilide, three drugs known to prolong cardiac action potentials and refractory periods, were studied by using a perfused isolated rabbit heart preparation with intermittent premature pacing and bipolar surface electrograms. The rate-related effects of these drugs on atrioventricular (AV) conduction were tested by pacing at a long (400 ms) and a short (250 ms) basic cycle length (BCL). All three drugs increased refractory periods in a concentration-dependent manner in most segments of the AV axis. The maximal atrio-His (AH) conduction interval (AHmax) and delta AH (AHmax - AHmin) produced by premature pacing was decreased by the highest concentration of each drug at the 400-ms BCL, whereas only clofilium reduced AHmax and delta AH at the 250-ms BCL. Changes in delta AH correlated best with changes in the atrial functional refractory period. The His-Purkinje system conduction interval (HV), represented by delta HV, was unaffected by any drug at either BCL. These results show that if atrial or nodal refractory periods are increased sufficiently, AHmax but not AHmin was decreased at the 400-ms BCL. Because dofetilide and risotilide did not affect AHmax at the 250-ms BCL, these drugs may be less effecti...Continue Reading

References

Jun 1, 1990·Journal of Cardiovascular Pharmacology·H Adaniya, M Hiraoka
Feb 1, 1974·The American Journal of Cardiology·K M RosenR A Miller
Apr 1, 1966·Circulation·B M HightowerJ W Kirklin
Jan 1, 1994·Journal of Cardiovascular Pharmacology·D S Krafte, W A Volberg
Mar 1, 1993·Pacing and Clinical Electrophysiology : PACE·M E Josephson, J M Miller
Oct 1, 1993·Journal of Cardiovascular Electrophysiology·M J JanseS Y Ho
Oct 1, 1993·Journal of Cardiovascular Electrophysiology·M A McGuireD L Ross
May 1, 1996·Journal of Cardiovascular Electrophysiology·C L CaseK W Hewett

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Citations

Oct 7, 2000·Clinical and Experimental Pharmacology & Physiology·H J Witchel, J C Hancox

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