Electrophysiological effect of volume load in isolated canine hearts

Hugh Calkins, William L Maughan, David A Kass, K. Sagawa, J. H. Levine

Research output: Contribution to journalArticle

Abstract

In isolated isovolumic ventricles and in in situ ventricles under nonsteady-state conditions, alterations in load have been shown to affect electrophysiological properties via contraction-excitation feedback. However, the effect of alterations in loading conditions on electrophysiological properties in normal ventricles under physiological loading conditions remains unknown. Furthermore, the arrhythmogenic significance of these load-induced electrophysiological changes is uncertain. We increased end-diastolic volume (27 ± 4 ml vs. 51 ± 6 ml) and assessed conduction, refractoriness, ventricular fibrillation thresholds (VFTs), and inducibility of ventricular arrhythmias in 14 isolated blood-perfused ejecting canine ventricles under steady-state conditions. We also examined the effect of increased end-diastolic volume on refractoriness and monophasic action potential (MAP) duration and contour under isovolumic versus ejecting conditions. Under ejecting conditions, increased end-diastolic volume resulted in very small (

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume256
Issue number6
StatePublished - 1989

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Ventricular Fibrillation
Action Potentials
Canidae
Cardiac Arrhythmias

ASJC Scopus subject areas

  • Physiology

Cite this

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AU - Calkins, Hugh

AU - Maughan, William L

AU - Kass, David A

AU - Sagawa, K.

AU - Levine, J. H.

PY - 1989

Y1 - 1989

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AB - In isolated isovolumic ventricles and in in situ ventricles under nonsteady-state conditions, alterations in load have been shown to affect electrophysiological properties via contraction-excitation feedback. However, the effect of alterations in loading conditions on electrophysiological properties in normal ventricles under physiological loading conditions remains unknown. Furthermore, the arrhythmogenic significance of these load-induced electrophysiological changes is uncertain. We increased end-diastolic volume (27 ± 4 ml vs. 51 ± 6 ml) and assessed conduction, refractoriness, ventricular fibrillation thresholds (VFTs), and inducibility of ventricular arrhythmias in 14 isolated blood-perfused ejecting canine ventricles under steady-state conditions. We also examined the effect of increased end-diastolic volume on refractoriness and monophasic action potential (MAP) duration and contour under isovolumic versus ejecting conditions. Under ejecting conditions, increased end-diastolic volume resulted in very small (

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