Circulation
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Comparative Study
Improved neurologic recovery and survival after early defibrillation.
Eighty-seven patients who had out-of-hospital cardiac arrests received defibrillating shocks delivered by minimally trained first responders before the arrival of paramedics in a city with short emergency response times. Their outcomes were compared with those of 370 other victims who received only basic life support by first responders until paramedics arrived. ⋯ Eighteen of 46 resuscitated patients (39%) receiving early defibrillation were awake at 24 hr compared with 49 of 204 patients (24%) who received only basic life support while awaiting paramedics (p less than .02). Incorporating defibrillation as part of basic life support can reduce both mortality and morbidity from cardiac arrest, even in cities with established, rapidly responding emergency care systems.
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Comparative Study
Mechanisms by which epinephrine augments cerebral and myocardial perfusion during cardiopulmonary resuscitation in dogs.
The goals of this study were to quantify the effects of epinephrine on myocardial and cerebral blood flow during conventional cardiopulmonary resuscitation (CPR) and CPR with simultaneous chest compression-ventilation and to test the hypothesis that epinephrine would improve myocardial and cerebral blood flow by preventing collapse of intrathoracic arteries and by vasoconstricting other vascular beds, thereby increasing perfusion pressures. Cerebral and myocardial blood flow were measured by the radiolabeled microsphere technique, which we have previously validated during CPR. We studied the effect of epinephrine on established arterial collapse during CPR with simultaneous chest compression-ventilation with the abdomen bound or unbound. ⋯ Although flows during CPR with simultaneous chest compression-ventilation without epinephrine were initially higher than those during conventional CPR, arterial collapse developed after 20 min, limiting cerebral and myocardial blood flow. The use of epinephrine throughout 50 min of CPR with simultaneous chest compression-ventilation maintained cerebral blood flow at 22 +/- 2 ml/min . 100 g (73 +/- 25% control) and left ventricular blood flow at 38 +/- 9 ml/min . 100 g (28 +/- 8% control). The improved blood flows with epinephrine correlated with improved electroencephalographic activity and restoration of spontaneous circulation.(ABSTRACT TRUNCATED AT 400 WORDS)
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One hundred twenty-two consecutive patients (104 men; 18 women) were studied to determine the incidence and natural history of pericardial effusion occurring 2, 5, 10, and 20 to 50 days after cardiac surgery. Three patients had pericardial effusions before and 103 patients (91 men; three women) had effusions after surgery. Effusions were first recorded on the second postoperative day in 72 patients, on the fifth postoperative day in 29 patients, and on the tenth postoperative day in two patients. ⋯ As the effusion became echo-dense, the posterior pericardium, which had been motionless, resumed its normal systolic anterior motion. One patient developed cardiac tamponade on postoperative day 3. We conclude that pericardial effusion occurs frequently after cardiac surgery, but that associated complications are rare.
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Dynamic obstruction to left ventricular outflow in patients with hypertrophic cardiomyopathy usually occurs when the anterior mitral leaflet moves forward in systole and approaches or contacts the ventricular septum. However, we have recently identified, by M mode and two-dimensional echocardiography, 21 patients with hypertrophic cardiomyopathy who had a unique pattern of mitral valve motion characterized by abnormal mitral valve coaptation and systolic anterior motion of the posterior mitral leaflet. This abnormality of mitral valve motion was most reliably identified with two-dimensional echocardiography in views of the left ventricle obtained from the apex. ⋯ Of the 16 patients who underwent cardiac catheterization, nine had basal subaortic gradients of 20 to 85 mm Hg, which were apparently due to moderate or marked systolic anterior motion of the posterior mitral leaflet. Ventricular septal myotomy-myectomies were performed in two patients and resulted in markedly diminished systolic anterior motion of the posterior mitral leaflet in each and abolition of subaortic gradient in the one patient who underwent postoperative cardiac catheterization. Hence, in patients with hypertrophic cardiomyopathy, systolic anterior motion of the posterior mitral leaflet (1) is not uncommon (identifiable in about 10% of a consecutively studied series of patients), (2) constitutes a previously undescribed mechanism for dynamic subaortic obstruction, and (3) is due to a malformation of the posterior mitral leaflet.
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Exercise radionuclide angiography is being used to evaluate left ventricular function in patients with aortic regurgitation. Ejection fraction is the most common variable analyzed. To better understand the rest and exercise ejection fraction in this setting, 20 patients with asymptomatic or minimally symptomatic severe aortic regurgitation were studied. ⋯ When peak oxygen uptake was excluded, rest and exercise ejection fraction also correlated significantly (r = -0.62 and r = -0.60, respectively, p less than 0.01). Patients with asymptomatic or minimally symptomatic severe aortic regurgitation have a wide spectrum of cardiac performance in terms of the PAWP during exercise. The absolute rest and exercise ejection fraction and the level of exercise achieved are noninvasive variables that correlate with exercise PAWP in aortic regurgitation, but the change in ejection fraction with exercise by itself is not.