Document Detail

Determination of effects of internal countershock by direct cardiac recordings during normal rhythm.
MedLine Citation:
PMID:  3706548     Owner:  NLM     Status:  MEDLINE    
Recording cardiac electrical activity after a countershock has been limited by amplifier saturation. Modifications to our computer-assisted mapping system allowed us to record electrical activity from 56 epicardial electrodes within 5 ms of the end of a countershock. Modifications included the use of solid-state switches to disconnect the filter section of the amplifiers during the shock and changing the low-frequency response of the amplifiers from 0.1 to 10 Hz to filter out large, low-frequency potentials after the shock. Six-millisecond truncated exponential shocks were delivered between the superior vena cava and right ventricular apex through a quadripolar catheter during normal rhythm in seven dogs. As shocks of increasing voltage were delivered during the T-Q interval, progressively more of the epicardium was directly depolarized. A shock of 109 +/- 17 (SD) V directly depolarized the entire epicardium. Shocks of constant voltage were then delivered with increasing prematurity during diastole. As the ventricles became more refractory with increasing shock prematurity, the amount of epicardium depolarized became progressively less. Thus computer-assisted mapping techniques are capable of measuring the area depolarized by a shock during normal rhythm and may be useful during arrhythmias to improve our understanding of defibrillation and cardioversion.
P G Colavita; P Wolf; W M Smith; F R Bartram; M Hardage; R E Ideker
Related Documents :
24847198 - Encoding of forelimb forces by corticospinal tract activity in the rat.
15183448 - Measuring myoelectric fatigue of the serratus anterior in healthy subjects and patients...
15250128 - Influence of stimulus frequency on nrt recordings.
14726298 - Virtual electrode theory explains pacing threshold increase caused by cardiac tissue da...
5579638 - Receptive fields of cones in the retina of the turtle.
7339328 - Contribution to the control of the locomotor activity of the dog.
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  250     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1986 May 
Date Detail:
Created Date:  1986-06-16     Completed Date:  1986-06-16     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H736-40     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Cardiology / instrumentation,  methods*
Electric Countershock*
Heart / physiology*
Time Factors
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Some consequences of capillary permeability to macromolecules: Starling's hypothesis reconsidered.
Next Document:  Heterogeneous response of subsarcolemmal heart mitochondria to calcium.