摘要:

To determine changes in the patterns of care between 1970 and 1980 for patients with uncomplicated acute myocardial infarction, questionnaires were sent to almost 6000 physicians in 1979 and responses were compared with those of a similar survey taken in 1970. Almost all physicians in 1979 reported the availability and use of an intensive care/coronary care unit facility with continuous electrocardiographic monitoring. Progressive-care facilities are also becoming more widely available. The median length of hospitalization has decreased markedly. Early ambulation and an earlier return to work are more common. There is a high level of informal patient and patient-family counseling about myocardial infarction and its management, both during and after hospitalization, and wider use of educational materials. Most physicians continue to recommend progressive physical activity after hospitalization.The routine prescription of anticoagulant therapy during hospitalization has declined, while prescription of prophylactic antiarrhythmic agents has increased. Nitrate drugs and tranquilizers are routinely prescribed by a large percentage of physicians for their patients with uncomplicated myocardial infarction.Use of standard exercise tests has increased among all physician specialties. The treadmill test is most often used, and testing is typically done 6 weeks after infarction. A significant increase in the availability of and familiarity with exercise testing is characteristic of all medical specialties.Symptoms of new chest pain and palpitations are now considered important enough to warrant the recommendation to report immediately to an emergency room. Other current findings include the routine use of coronary angiography by a large percentage of physicians to evaluate the need for surgical intervention, and the routine posthospitalization prescription by only a small percentage of physicians of aspirin and of nitrate drugs for patients with uncomplicated myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

Electrical stimulation of the carotid sinus nerves was applied during diagnostic catheterization of two patients who had coronary artery disease. The immediate reflex prolongation of the atrioventricular (AV) interval was due to prolongation of the AH interval only and was roughly parallel to the reflex RRAinterval prolongation evoked without atrial pacing. After cholinergic block, the reduced prolongation of both the RR interval and the AV interval caused by reflex inhibition of sympathetic tone followed a time course similar to the arterial pressure decrease. This is the first demonstration in man of the parallel baroreflex effects on the sinoatrial node and the AV node.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

To evaluate whether heart-rate-induced changes of the QT interval are dependent on autonomic tone, we studied 13 healthy subjects, mean age 67.5 years. The maximal uncorrected QT from leads I, II, V1and V6was determined during atrial pacing at 90 beats/min and 130 beats/min before and after i.v. administration of propranolol, 0.1 mg/kg, and atropine, 0.02 mg/kg.Significant reductions (p< 0.01) of QT were induced by the paced increases in heart rate before drugs (10%), after propranolol (10%) and after the combination of atropine and propranolol (9%). Propranolol caused no significant change in the QT interval when heart rate was held constant by pacing. In contrast, atropine produced rate-independent reductions of QT interval (5%) in subjects with β-adrenergic blockade (p< 0.05). Bazett's formula for heart-rate correction of the QT interval (QTc) was not applicable for atrial overdrive pacing, as it gave proportionately longer QTc values at higher heart rates.These results show that heart rate is a major determinant of the duration of the QT interval and that paced changes in heart rate induce QT-interval responses that are essentially uninfluenced by autonomic tone. The rate-independent effect of the QT interval produced by elimination of cholinergic tone suggests a direct influence of cholinergic activity on the repolarization of ventricular myocardium.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

The effect of increased lung conductivity on ECG potentials was studied in human subjects undergoing pulmonary lavage of a whole lung. In this procedure, the air in the lung is replaced by physiologic saline solution, which is a highly conductive fluid. The same situation was simulated theoretically with an eccentric spherical model of the heart and torso. Both the experimental results and theoretical simulations show a decrease in body-surface potentials as the lung conductivity increases. In particular, a large decrease was observed in the posterior vector and the scalar Z lead both experimentally and theoretically. The model simulation shows that the scalar Z lead is maximal at a conductivity value that is very close to the typical normal lung conductivity, so that low voltages are predicted for low lung conductivities as well.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

To assess whether gross pathologic differences exist between hearts with left bundle branch block (LBBB) and left-axis deviation (LAXD) and those with LBBB and a normal frontal plane axis, we examined 70 hearts with LBBB in a series of 1410 sequential dissections (5%). Thirty-two hearts had LAXD and 34 had normal axes on the correlative ECG. Left ventricular enlargement occurred frequently (93%). No significant differences were found in age distribution, left ventricular weight, coronary anatomy or infarct location. Quantitative analysis revealed larger inferoposterolateral and apical infarcts in hearts with LBBB and LAXD (p< 0.01). The accuracy of various electrocardiographic signs of left ventricular enlargement and myocardial infarction in the presence of LBBB was assessed. Voltage criteria and QRS duration poorly define anatomic chamber enlargement. Anterior infarction is suggested by a q or pathologic Q wave in lead I, a q wave in leads I, V5and V6or notched S waves in V3 or V,. Pathologic Q waves or ST shifts in the inferior leads have high diagnostic specificity but low sensitivity for inferior infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

To assess the prognosis of patients with a strongly positive exercise ECG, the 5-year cumulative survival rate was computed for 220 medically treated patients. Of these patients, 107 had coronary angiograms (group A) and 113 did not (group B). All had horizontal or downsloping ST depression 2 mm during a multistage Bruce protocol treadmill exercise test. In group A, the overall 5-year survival rate was 74 5%. Survival decreased with decreasing duration of exercise: All patients who achieved stage IV (541 seconds or more) survived, whereas the survival rate was 86 ± 6% when the patients terminated their exercise during stage III (361-540 seconds), 73 ± 7% when during stage 11 (181-360 seconds) and only 52 ± 13% when during stage I (180 seconds or less). The mortality was associated with more severe coronary artery disease, and sudden death was the main cause of death. Patients in group B had a longer mean exercise duration than those in group A and, as expected, a higher survival rate (91 ± 3%, p < 0.01), which also varied according to the exercise duration. Among patients with a strongly positive exercise ECG, the duration of exercise identifies subsets that have different survival rates.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

One hundred forty-two deaths among 743 men ages 50-65 years who had been examined and followed 5-10 years were investigated and classified on the basis of clinical information from medical and nonmedical observers, ECGs and autopsies. A classification based on the condition of the circulation immediately before death appears to be most relevant to studies of sudden death.In 58% of the cases, the subject collapsed abruptly and his pulse ceased without prior circulatory collapse (arrhythmic death); in 42%, the pulse ceased only after the peripheral circulation had collapsed (deaths in circulatory failure). Thirty-three percent of arrhythmic deaths and 10% of deaths in circulatory failure occurred in a setting of clinical evidence of acute ischemic heart disease (p< 0.005). Forty-five percent of arrhythmic deaths were preceded by chronic congestive heart failure without circulatory collapse. Ninety-three percent of final illnesses that lasted less than 1 hour ended in arrhythmic deaths; 74% that lasted more than 1 day ended in deaths in circulatory failure (p< 0.001). Eighty-eight percent of deaths that occurred outside of the hospital were arrhythmic; 71% of deaths that occurred in the hospital were deaths in circulatory failure (p< 0.001). Ninety percent of deaths in which the primary cause of the final illness was heart disease were arrhythmic; 86% of deaths in which the primary cause was other than heart disease were deaths in circulatory failure (p< 0.001). Ninety-one percent of deaths precipitated by an acute cardiac event were arrhythmic; 98% precipitated by acute respiratory obstruction, hemorrhage, infection, stroke or other noncardiac events were deaths in circulatory failure (p< 0.001).

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

This study was undertaken to examine in vivo the effects of cigarette smoke on cyclic reductions in coronary flow due to platelet thrombus formation in the stenosed coronary arteries of anesthetized dogs. The circumflex coronary artery of 21 mongrel dogs was stenosed 60-80%, with blood flow measured with an electromagnetic flow probe. After the administration of cigarette smoke, plasma epinephrine was elevated nine times the control level (p< 0.001) and peak mean blood pressure was elevated one and one-half times control (p< 0.01). The hematocrit increased several percent (p< 0.01) with cigarette smoke, although blood gases and pH remained unchanged. In all 21 dogs, spontaneous reductions in coronary blood flow were greatly exacerbated in the stenosed circumflex artery as evidenced by the number of flow reductions, the increased size of the reductions and the rate of flow reduction. Nicotine administered intravenously in doses comparable to those achieved through absorption of cigarette smoke by the lungs provoked similar responses of a-adrenergic stimulation and potentiation of the platelet thrombus formation. An a-adrenergic antagonist, phentolamine, was given (3 mg/kg) intravenously to inhibit the exacerbated platelet thrombus formation due to cigarette smoke or infused nicotine. In 18 of 21 dogs, an acute occlusive platelet thrombus was prevented 15 minutes after phentolamine and after a cigarette smoke or nicotine challenge. This study confirms a link between cigarette smoking, platelet thrombus formation, and the potential for humans to develop an acute occlusive platelet thrombus in a diseased and stenotic coronary artery.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID

摘要:

A lack in prostacyclin (PGI2) production due to atherosclerosis may play a role in the pathophysiology of some of the clinical manifestations of ischemic heart disease and, in particular, of coronary vasospasm. We therefore evaluated the effects of i.v. PGI, in nine patients with variant angina and six normal volunteers.In normal subjects, PGI2 (2.5, 5, 10 and 20 jg/kg/min) had significant antiplatelet effects, caused a dosedependent decrease in both systolic and diastolic arterial pressure and a decrease in pulmonary resistance. Heart rate increased in a dose-dependent manner, but no consistent effects on myocardial contractility (evaluated by ultrasound) were observed. Side effects were negligible and readily reversible. Although producing obvious antiplatelet and vasodilatory effects, PGI2 did not affect the number, severity and duration of spontaneous ischemic episodes due to coronary vasospasm in five patients and ergonovineinduced spasm in three. However, the number of ischemic episodes was consistently reduced in one patient during four consecutive periods of PGI2 infusion alternated with placebo. A severe, prolonged ischemic episode with ST elevation and pain was consistently observed in this patient every time PGI2 was discontinued.In the appropriate environment, PGI2 can be administered safely to patients with ischemic heart disease. Occasionally, PGI2 may result in a complete disappearance of ischemic episodes due to coronary vasospasm, but usually it is ineffective. These conflicting results could be related to different etiologies of coronary spasm.

ISSN:0009-7322    

出版商:OVID    

年代:1982

数据来源: OVID