Pacing and clinical electrophysiology : PACE
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Our study included the treatment of transcutaneous cardiac pacing (TCP) in 32 patients: (A) 19 patients were treated in the emergency area for complete symptomatic AV block before endocavitary pacing; (B) five patients were in asystole following DC shock or out-of-hospital cardiac arrest; and (C) eight patients were affected by bifascicular block undergoing emergency surgery and were treated in order to prevent complete AV block. Two transcutaneous stimulators were used. PaceAid-CRC model 50/52 with 20-msec pulse width; the electrodes were positioned on the V3 ECG position and on the back. ⋯ in all but two patients, it was possible to obtain stable cardiac capture; in one patient arrived in hospital in asystole after prolonged cardiac arrest and in the other one was affected by complete AV block, TCP was ineffective. In groups A and B, TCP was maintained for a mean time of 15 minutes; in group C, TCP was tested in all patients, but performed in only one patient during surgery. Mean threshold was 81 mA. Stimulation was well tolerated in all but five patients. TCP is a reliable, noninvasive method that offers the possibility to initiate pacing within seconds and can be used by medical staff. In our opinion, it should be considered as the first choice emergency treatment of severe symptomatic bradycardia. In asystole, beneficial effects can be obtained only if TCP is performed early enough after the onset of arrhythmia.
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The focus of this report is to describe a system for recording surface His-Purkinje and ventricular late potentials on a beat-by-beat basis outside of a shielded environment. An AC magnetic field monitoring device was designed for improved site selection, orientation, and quality control of the acquisition. His-Purkinje signals are detected utilizing spatial averaging and specific channel selection algorithms applied to discriminate random noise from signal. ⋯ While filter ringing was eliminated, discontinuity and distortion of the filtered waveform resulted. The FIR filter with linear phase response retained the integrity and morphology of the complex but because of its flat frequency response, the ST segment was not as well attenuated and it was more difficult to isolate late potentials. A high order FIR filter should be used if the desire is to match the frequency response of the four-pole IIR filter, since the frequency response of the FIR filter is primarily determined by the order of the filter.(ABSTRACT TRUNCATED AT 250 WORDS)