Circulation
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Editorial Comment Randomized Controlled Trial Clinical Trial
Are implantable cardioverter-defibrillators better than conventional antiarrhythmic drugs for survivors of cardiac arrest?
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Randomized Controlled Trial Clinical Trial
Truncated biphasic pulses for transthoracic defibrillation.
Early defibrillation is the single most important factor for improving out-of-hospital ventricular fibrillation resuscitation rates. To achieve the earlier response times required for survival, typically < 6 minutes from time of collapse, it will be necessary to equip a far wider network of first responders (firefighters, police, and other individuals with responsibility for public safety) with small, lightweight, and inexpensive automatic external defibrillators (AEDs). An important step in reducing the size and cost of AEDs will be to improve defibrillation efficacy. Because biphasic waveform defibrillation has had a favorable impact on implantable cardioverter-defibrillators (ICDs), there are reasons to believe that biphasic waveforms would also improve transthoracic defibrillators. Our purpose, therefore, was to examine the efficacy of two different low-energy biphasic truncated waveforms referenced to a standard damped sine waveform for transthoracic defibrillation in humans. ⋯ The results of this study suggest that biphasic truncated transthoracic shocks of low energy (115 and 130 J) are as effective as 200-J damped sine wave shocks used in standard transthoracic defibrillators. This finding may contribute significantly to the miniaturization and cost reduction of transthoracic defibrillators, which could enable the development of a new generation of AEDs appropriate for an expanded group of out-of-hospital first responders and, eventually, layperson use.
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Randomized Controlled Trial Clinical Trial
Current spectrum of cardiogenic shock and effect of early revascularization on mortality. Results of an International Registry. SHOCK Registry Investigators.
Cardiogenic shock remains the leading cause of death of patients hospitalized with acute myocardial infarction (MI). This study was conducted to examine (1) the current spectrum of cardiogenic shock, (2) the proportion of patients who are potential candidates for a trial of early revascularization, and (3) the apparent impact of early revascularization on mortality. ⋯ Patients diagnosed with cardiogenic shock complicating acute MI are a heterogeneous group. Those eligible for a trial of early revascularization tended to have lower mortality. Patients selected to undergo cardiac catheterization had lower mortality whether or not they were revascularized. Emergent PTCA and CABG are promising treatment modalities for cardiogenic shock, but biased case selection for treatment may confound the data. Whether PTCA and CABG reduce mortality and which patient subgroups benefit most remain to be determined in a randomized clinical trial.
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Randomized Controlled Trial Clinical Trial
Role of cardiac beta 2-receptors in cardiac responses to exercise in cardiac transplant patients.
In healthy human hearts, beta 2-receptor-mediated chronotropic and inotropic responses contribute to the cardiac responses to beta-agonists. A (patho)physiological relevance for beta 2-receptor-mediated responses has so far not been demonstrated, in part because beta 1-receptor-mediated responses to cardiac neuronally released norepinephrine can mask beta 2-receptor-mediated responses. ⋯ The present study shows that cardiac beta 2-receptors contribute to a clear extent to the heart rate responses to endogenous circulating catecholamines in the absence of cardiac neuronally released norepinephrine. Nonselective beta-blockade probably is less well tolerated in cardiac transplant patients compared with beta 1-selective blockade.
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Randomized Controlled Trial Comparative Study Clinical Trial
Cardiopulmonary bypass, temperature, and central nervous system dysfunction.
Neurological injury is an important cause of morbidity and mortality after cardiac surgery. With the advent of warm heart surgery, the neuroprotective role of hypothermic cardiopulmonary bypass (CPB) has come under increasing scrutiny. Preliminary work by us in the area found no increased risk of neurological morbidity with normothermic CPB in a small group of patients and suggested a possible benefit. The purpose of the present study is to compare the incidence of neurological and neuropsychological dysfunction in a larger number of patients randomized to warm or cold aortocoronary bypass surgery. ⋯ In this randomized trial of normothermic versus hypothermic CPB, we found deterioration in scores of tests of psychomotor speed but not of memory in the early postoperative period. We were unable to demonstrate any neuroprotective effect from moderate hypothermia in this patient population.