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PubMed · 3048515

Automatic implantable defibrillators.

I G Crozier·D E Ward
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Abstract

The automatic implantable defibrillator was developed in the USA by Mirowski. This device automatically detects ventricular fibrillation or ventricular tachycardia and delivers a low energy (30 J) shock directly to the myocardium via patch electrodes on the epicardial surface or through a combination of a pericardial patch and an endocardial wire. These devices are being implanted in large numbers in the USA and represent a major contribution to the management and refractory ventricular arrhythmias. Unfortunately their high cost has limited their use in this country despite impressive clinical results.

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Electric CountershockHumansProstheses and ImplantsTachycardiaVentricular FibrillationJournal ArticleResearch Support, Non-U.S. Gov'tReview

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I G Crozier, D E Ward. 1988. Automatic implantable defibrillators.. https://pubmed.ncbi.nlm.nih.gov/3048515/

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PubMed1992

Use of telemetry functions in the assessment of implanted antitachycardia device efficacy.

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PubMed1992

Prospective comparison of biphasic and monophasic shocks for implantable cardioverter-defibrillators using endocardial leads.

Bidirectional shocks using 2 current pathways have been used in endocardial lead systems for implantable cardioverter-defibrillators, but the optimal shock waveform for endocardial defibrillation is unknown. The clinical efficacy and electrical characteristics of bidirectional monophasic and biphasic shocks for endocardial cardioversion-defibrillation of fast monomorphic or polymorphic ventricular tachycardia (VT), or ventricular fibrillation (VF) were evaluated. Thirty-three patients (mean age 60 +/- 12 years, and mean left ventricular ejection fraction 34 +/- 13%) were studied. Defibrillation catheter electrodes were located in the right ventricular apex and superior vena cava/right atrial junction. A triple-electrode configuration including the 2 catheter electrodes and a left thoracic patch was used to deliver bidirectional shocks from the right ventricular cathode to an atrial anode (pathway 1) and the thoracic patch (pathway 2). The shock waveforms examined were sequential and simultaneous monophasic, and simultaneous biphasic. The efficacy of 580 V (20 J) shocks for fast monomorphic VT were comparable for the 3 waveforms (73% for sequential monophasic, 73% for simultaneous monophasic, and 100% for simultaneous biphasic). However, for polymorphic VT and VF, 580 V sequential monophasic shocks had a significantly lower efficacy (25%) than did simultaneous monophasic (75%; p = 0.01) or biphasic (89%; p less than 0.001) shocks. Single-shock defibrillation thresholds with simultaneous biphasic shocks were significantly lower (9 +/- 5 J) than were those with simultaneous monophasic shocks (15 +/- 4 J; p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

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