Defibrillation of 100 kg calves with asymmetrical, bidirectional, rectangular pulses

• Published in: Cardiovascular research 1984-07, Vol.18 (7), p.419-426
• Main Authors: SCHUDER, JOHN C, McDANIEL, WAYNE C, STOECKLE, HARRY
• Format: Article
• Language: English
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Biological and medical sciences; Cattle; defibrillatory shocks with undershoot; Electric Countershock; Electrocardiography; Emergency and intensive cardiocirculatory care. Cardiogenic shock. Coronary intensive care; Intensive care medicine; large animal defibrillation; Medical sciences; postdefibrillation electrocardiogram in calves; Time Factors; transthoracic defibrillation; Ventricular Fibrillation - therapy
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1093/cvr/18.7.419

The effectiveness in reversing ventricular fibrillation of 30 s duration of asymmetrical, bidirectional, rectangular waveforms in which the lagging half-cycle has the same duration but lower amplitude than the leading portion of the waveform was evaluated in a 2160-episode study involving anaesthetised calves. An additional 480-episode auxiliary study involved the interlacing of unidirectional and bidirectional wave episodes. The leading half-cycles of the 18 bidirectional waveforms evaluated were 35 A at 8 and 16 ms, 50 A at 4 and 8 ms, and 70 A at 2 and 4 ms. Associated with each of the six leading half-cycle configurations were lagging half-cycles having reverse current levels of l/8th, l/4th, and 1/2 of the leading half-cycle current amplitudes. Six waveforms were successful in 97% or more of the transthoracic episodes. Of these, three were 100% successful. Our data, when combined with those from earlier unidirectional and symmetrical, bidirectional, rectangular waveform studies, suggest that a broad category of bidirectional rectangular shocks are superior to the most favourable unidirectional rectangular shock.