Genesis of sigmoidal dose-response curve during defibrillation by random shock: a theoretical model based on experimental evidence for a vulnerable window during ventricular fibrillation.
The sigmoidal dose-response curve (percent success vs shock energy) suggests a probabilistic nature of defibrillation. The mechanism is still largely unknown, however, random variation in the excitable state during ventricular fibrillation (VF) is suspected. A canine defibrillation study was designe...
| Published in: | Pacing & Clinical Electrophysiology Vol. 13; no. 10; pp. 1326 - 1343 |
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| Main Authors: | , |
| Format: | Journal Article |
| Published: |
Wiley-Blackwell
Oct1990
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| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=105716954&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 105716954 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 01478389 4F8 jtl: Pacing & Clinical Electrophysiology issn: 01478389 maglogo: Y pubinfo: dt: Oct1990 vid: 13 iid: 10 pid: 480 pub: Wiley-Blackwell place: Malden, Massachusetts artinfo: ui: 105716954 2009413308 NLM1701547 105716954 ppf: 1326 ppct: 17 formats: fmt: @attributes: type: P tig: atl: Genesis of sigmoidal dose-response curve during defibrillation by random shock: a theoretical model based on experimental evidence for a vulnerable window during ventricular fibrillation. aug: au: Hsia PW Mahmud R sug: subj: Cardioversion Statistics and Numerical Data Electrocardiography Methods Signal Processing, Computer Assisted Ventricular Fibrillation Therapy Animals Dogs Female Male Models, Theoretical Female Male ab: The sigmoidal dose-response curve (percent success vs shock energy) suggests a probabilistic nature of defibrillation. The mechanism is still largely unknown, however, random variation in the excitable state during ventricular fibrillation (VF) is suspected. A canine defibrillation study was designed to determine whether random variation in absolute VF voltage (AVFV) (a crude marker of number of excitable cells) was related to success of defibrillation, using a DC shock successful at the 50% level. The results were: (a) transmyocardial resistance (73.4 ± 1.4 vs 73.6 ± 1.5 ohms) and delivered energy (6.1 ± 1.2 vs 6.2 ± 1.2 joules) were similar; however, (b) AVFV 2 msec prior to DC shock was greater for successful as compared to unsuccessful attempts (0.5 ± 0.1 vs 0.3 ± 0.0 mV, P < 0.01). A mathematical model was subsequently developed based on fluctuation in the number of excitable cells. Variation in the state of excitability resulted in a cyclic window potentially vulnerable to defibrillation. The vulnerable window occurred at a point when the number of excitable cells was low, i.e., a higher state of total depolarization, which was in agreement with the experimental finding. For a given VF pattern, duration of the vulnerable window was regulated by the shock energy. A larger shock energy generated a wider vulnerable window and, in turn, a higher success rate. Finally, the sigmoidal dose-response curve of defibrillation was theoretically constructed by calculating the variable chances of a random DC shock occurring either in a vulnerable window or elsewhere during VF. It is concluded that a vulnerable window susceptible to defibrillation can be demonstrated in the early stages (10 sec) of VF. The mathematical model provides a theoretical basis for the vulnerable window and helps elucidate the probabilistic nature of defibrillation. pubtype: Academic Journal doctype: Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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