Pacing and clinical electrophysiology : PACE
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Pacing Clin Electrophysiol · Aug 1989
Randomized Controlled Trial Comparative Study Clinical TrialActive fixation atrial leads: randomized comparison of two lead designs.
Active fixation leads have reduced the incidence of lead dislodgement in patients with permanent pacemakers. However, theoretic concern that the tissue trauma associated with a myocardial screw-helix may increase the chronic pacing threshold of active compared to passive fixation leads has remained. Whether active fixation leads with a stimulating electrode that is independent of the fixation mechanism are associated with a lower chronic pacing threshold than leads utilizing a screw-helix for both fixation and stimulation is unknown. ⋯ At 6 weeks follow-up, there were no differences in the mean threshold voltage (1.85 +/- 0.36 vs 1.93 +/- 0.69 V), impedance (528 +/- 81 vs 530 +/- 118 ohms), or atrial electrogram amplitude (2.63 +/- 0.50 vs 2.42 +/- 0.95 mV) between the two leads. At long-term follow-up (mean 16.2 +/- 2.8 months, range 13.1-20.0 months) there were no significant differences in voltage threshold (1.65 +/- 0.61 vs 1.97 +/- 0.64 V), impedance (565.5 +/- 81.6 vs 617.7 +/- 146.7 ohms), or atrial electrogram amplitude (2.79 +/- 0.75 vs 3.10 +/- 1.53 mV). Thus, these results suggest that active fixation leads in the atrium with an electrode that is independent of the fixation mechanism do not provide chronic stimulation thresholds or electrogram amplitudes that are superior to those obtained with leads utilizing a myocardial screw-helix as both the active electrode and the fixation device.
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Spinal cord stimulation is considered to be ineffective in relieving deafferentation pain. We have retrospectively analyzed the results obtained in a series of 41 patients. Sixteen suffered from pain associated with an incomplete traumatic spinal lesion, 15 from a posttherapeutic neuralgia, and 10 from pain due to root and/or nerve damage. ⋯ The mean analgesia achieved was 70%. From this analysis we conclude that the results achieved in the postherapeutic pain patients, although positive in only 66% of them, are remarkably stable with time. Therefore, we recommend a percutaneous test trial of SCS in every case of postherapeutic pain resistant to medical treatment.
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Thirteen patients with post-stroke spastic hemiparesis underwent a percutaneous test trial of spinal cord stimulation (SCS) in order to modify their motor disturbances. Clinical evaluation based on Albert's motor scale and neurophysiological evaluation consisting of surface EMG during voluntary, involuntary, and reflex motor activity were performed before and during SCS. At the end of the test period, eight patients showed a significant improvement in their motor performance. ⋯ SCS was followed by a reduction or disappearance of synergic coactivation with better agonist-antagonist coordination, a decrease of clonus both in duration and spreading, and better endurance. The effect on motor control did not increase with time after the first month of SCS, but was long lasting (mean follow-up: 2 years). There was a correlation between sensory deficit and motor outcome suggesting that the enhancement of sensory input put into play by SCS and the consequent development of new sensory-motor integration might be responsible for the improvement in motor performance.
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Transcutaneous cardiac pacing using the Pace-Aid (Cardiac Resuscitator Corporation) was assessed in 32 emergency patients presenting with profound bradycardia or asystole who had failed to recover with advanced life support including the use of epinephrine. Pacing stimuli, pulse width 20 ms at 50, 100, or 200 mA, were delivered through two 8 cm gel-pad electrodes placed antero-posteriorly on the chest. By ECG criteria, definite electrical capture was achieved in a total of five patients and possible capture in a further 16. ⋯ None in the asystolic group survived. Difficulties in using the Pace-Aid resulted from electrical overload by the pacing impulse that obscured the evidence for electrical capture, and intense muscle contraction that hindered reliable palpation of the arterial pulse. Transcutaneous pacing can occasionally be of value even at a late stage in the emergency treatment of profound bradycardia but is unlikely to be worthwhile in complete asystole.
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We now know that the elements required to achieve the highest survival rates from out-of-hospital cardiac arrest include: witnessed arrest, rapid telephone notification of the emergency medical service, early initiation of cardiopulmonary resuscitation, rapid arrival within minutes of emergency personnel equipped with a defibrillator, and early advanced airway management and intravenous pharmacology. In the United States, and in several other countries innovative approaches have been tried to bring all these elements together in one system. ⋯ New studies are in progress with the prehospital use of early transcutaneous cardiac pacing and these show promise. This article reviews the evidence that supports these multi-layered and innovative approaches to the treatment of out-of-hospital cardiac arrest.