PubMed · 4171317
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
1968. [External electric shock].. https://pubmed.ncbi.nlm.nih.gov/4171317/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
This study examines in a prospective, multicenter trial the feasibility and advantage of current-based, transthoracic defibrillation. Current-based, damped, sinusoidal waveform shocks of 18, 25, 30, 35, or 40 amperes (A) were administered beginning with 25 A for polymorphic ventricular tachycardia (VT) and ventricular fibrillation (VF) or 18 A for monomorphic VT; success rates were compared with those of energy-based shocks beginning at 200 J for VF/polymorphic VT and 100 J for VT. The current-based shocks were delivered from custom-modified defibrillators that determined impedance in advance of any shock using a "test-pulse" technique; the capacitor then charged to the exact energy necessary to deliver the operator-selected current against the impedance determined by the defibrillator. Three hundred sixty-two patients received > 1 shock for VF, polymorphic VT, or monomorphic VT: 569 current- based shocks and 420 energy-based shocks. Current-based shocks of 35/40 A achieved success rates of up to 74% for VF/polymorphic VT; 30 A shocks terminated 88% of monomorphic VT episodes. Energy-based shocks of 300 J terminated 72% of VF/polymorphic VT; 200-J shocks terminated 89% of monomorphic VT. We could not demonstrate a significant increase in the success rate of current-based shocks over energy-based shocks for patients with high transthoracic impedance; this may be due to inadequate sample size. Thus, current-based defibrillation is clinically feasible and effective. A larger study will be needed to test whether current-based defibrillation is superior to energy-based defibrillation.
Explore the source record for details and available documents.
It is shown that inhomogeneity due to gap junctional resistance allows an excitable cable to be directly activated or defibrillated by the application of a large amplitude point stimulus of short duration. Multiple-scale analysis is used to derive a model equation describing the response of the excitable medium to stimuli, and this equation is analyzed to give quantitative estimates of the direct stimulus threshold and the defibrillation threshold. These estimates are shown to be in good agreement with experimental findings.