Linked Life Data

8656107

Source:http://linkedlifedata.com/resource/pubmed/id/8656107

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1996-7-26
pubmed:abstractText
Experimental and clinical observations confirm that certain biphasic (BP) defibrillation shocks are significantly more efficacious than equivalent monophasic (MP) shocks, yet the mechanisms underlying these improvements are still not well understood. The authors used two separate, but related, computer models to investigate in detail the excitation responses of active cardiac cells and tissue to idealized premature extracellular MP and BP field stimuli. The results revealed a large disparity in MP and BP excitation responses to low-strength, but not high-strength, fields. In particular, at these low-strength levels, the polarity reversal within BP shocks effectively extends excitability to earlier cellular refractory states than can be achieved with simple MP shocks. Moreover, whereas low-strength MP shocks induce a distinct all-or-none excitatory response to varying shock prematurities, the excitatory response to equivalent BP shocks remains highly graded. In tissue simulations where such field stimuli intersected propagating wave fronts, the all-or-none excitatory response elicited by low-strength MP shocks created a postshock discontinuity in the spatial transmembrane voltage profile, which initiated a new propagation wave front. In contrast, the graded excitatory response elicited by BP waveforms effectively prevented the formation of postshock wave fronts. High-strength MP and BP stimuli prevented renewed propagation equally well. In conclusion, these results suggest a new mechanisms for BP defibrillation superiority over MP waveforms: that the graded excitatory response to BP stimuli at low-field strengths effectively prevents the formation of large spatial transmembrane voltage gradients, which can lead to renewal of propagated wave fronts.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:issn
0022-0736
pubmed:author
pubmed:issnType
Print
pubmed:volume
28 Suppl
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
174-9
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Cardiac responses to premature monophasic and biphasic field stimuli. Results from cell and tissue modeling studies.
pubmed:affiliation
Johns Hopkins University School of Medicine, Department of Biomedical Engineering, Baltimore, Maryland, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.