Document Detail

Efficacy and safety of defibrillation with rectangular waves of 2- to 20-milliseconds duration.
MedLine Citation:
PMID:  6822087     Owner:  NLM     Status:  MEDLINE    
The effect of suprathreshold defibrillator shocks on cardiac function was compared in 8 isolated, perfused, contracting canine hearts using 4 durations of rectangular electrical waveforms. Defibrillation threshold was first determined for each duration; then overdose shocks of 3, 4.5, 6, and 9 times threshold current density were delivered. Left ventricular isovolumic systolic pressure decreased immediately after the shocks in proportion to the overdose shock strength. The mean defibrillation current density thresholds for the 2-, 5-, 10-, and 20-msec durations were 101, 63, 47, and 39 mA/cm2, respectively. The corresponding energy density thresholds were 4.6, 3.5, 4.4, and 6.4 mJ/cm3, respectively. The safety factor for defibrillation was defined as the current overdose ratio (delivered current density/threshold current density) required to produce a 50% decrease in isovolumic systolic pressure immediately after the shock. This dose was determined by interpolation of the curve for depression versus overdose of shock strength. The mean current safety factors for the 2-, 5-, 10-, and 20-msec durations were 3.9, 5.1, 5.4, and 5.2, respectively. The corresponding mean energy safety factors were 15, 25, 28, and 27. The margin of safety for functional depression of the heart was significantly less (p less than 0.05) for the 2 msec rectangular wave then for the 5-, 10-, and 20-msec rectangular waves.
M J Niebauer; C F Babbs; L A Geddes; J D Bourland
Related Documents :
6708297 - Effects of intraaortic balloon pumping on acute myocardial infarction in 64 cases of ca...
16441717 - Importance of initiation pattern of polymorphic ventricular tachycardia in patients wit...
10202167 - Temporal trends in cardiogenic shock complicating acute myocardial infarction.
6181287 - The pathophysiologic role of myocardial depressant factor as a mediator of circulatory ...
16817177 - Early administration of abciximab bolus in the emergency department improves angiograph...
2632817 - Relation between mixed venous blood oxygen saturation and cardiac pumping function at t...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Critical care medicine     Volume:  11     ISSN:  0090-3493     ISO Abbreviation:  Crit. Care Med.     Publication Date:  1983 Feb 
Date Detail:
Created Date:  1983-03-24     Completed Date:  1983-03-24     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  95-8     Citation Subset:  AIM; IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Blood Pressure
Electric Countershock / adverse effects*
Electric Stimulation / adverse effects
Time Factors
Grant Support

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

Previous Document:  Diagnostic and prognostic value of auditory nerve brainstem evoked responses in comatose children.
Next Document:  T3 may be a better agent than T4 in the critically ill hypothyroid patient: evaluation of transport ...