ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Hemodynamic and clinical evaluations of 123 patients with acute myocardial infarction were performed during the first hour of admission to the hospital. In the 123 patients, the right atrial pressure was less than 10 mm Hg in 49 patients, the right atrial oxygen saturation was less than 70% in 97 patients, the arteriovenous oxygen difference was greater than 5.0 vol% in 78 patients. The arterial Po2was less than 90 mm Hg in 101 of 107 patients who could be evaluated while breathing room air. The cardiac index was depressed below 3.0 L/min/m2in 65 of 98 patients.The hemodynamic findings generally correlated with the clinical status of the patient; however, within each clinical class of patients there was a wide spectrum of values for each measurement evaluated. There was also considerable overlap of the values found within each clinical classification. It is concluded that hemodynamic evaluation of patients with acute myocardial infarction presents a profile of the patient which is frequently different from the profile that clinical evaluation presents. An objective hemodynamic classification of patients with acute myocardial infarction may provide a more useful index for the evaluation of the patient's prognosis and for the assessment of preventative therapy.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

One hundred patients admitted to a cardiac care unit had indirect serial determinations of left ventricular systolic ejection times. Patients were divided into groups with transmural infarction, nontransmural infarction, and no infarction, according to clinical, biochemical, and electrocardiographic criteria. Total electromechanical systole and left ventricular ejection time were shortened in acute myocardial infarction, whereas the pre-ejection period and its components, the Q-S1and isovolumic contraction time intervals, were prolonged. The most abnormal measurements were observed in patients with transmural infarction. Patients with nontransmural infarction demonstrated less severe abnormalities of the systolic ejection times, and the patients without infarction were the least affected. Some of the greatest deviations in the measured intervals were observed in the transmural infarction patients who died. Indirect measurement of left ventricular systolic ejection time is a valuable adjunct in the bedside assessment of left ventricular performance and provides a prognostic index for patients with acute myocardial infarction.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Eight patients with coronary heart disease were studied during two periods of exercise separated by 30 min of rest; workload was increased in a stepwise fashion every minute of exercise up to a level that produced limiting symptoms of angina, fatigue, or dyspnea. The magnitude of ST-segment depression and the central aortic pressure were measured during exercise and recovery periods, and myocardial oxygen requirements were estimated by the pressure-time index (systolic aortic pressure × heart rate × ejection time).Seven of the eight patients exhibited a close relationship (r ranged from 0.74 to 0.98) between magnitude of exercise ST-segment depression and indices expressing myocardial oxygen requirements; heart rate, blood pressure, and ejection time were also related to magnitude of exercise ST-segment depression. These relationships were reproducible during two consecutive exercises. Like onset of angina, magnitude of exercise ST-segment depression is usually related to hemodynamic factors influencing myocardial oxygen needs. Consequently, comparisons of exercise-induced ST depression before and after therapy (drugs, physical training, and surgery) are valid only if ECG findings are compared at the same level of myocardial oxygen requirements.In contrast, absence of such a relationship during recovery suggests an important difference in mechanisms of the post-exercise electrocardiogram.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Right atrial pacing was performed in 41 subjects with coronary heart disease. Twenty developed angina pectoris during pacing, while 21 did not. The extent of coronary artery disease, as judged by selective cinearteriography, was similar in the two groups. Both had significant increases in heart rate and pressure-time per minute, but there was no significant difference in either of these parameters between groups. Among the hemodynamic parameters measured, the only statistically significant change was in the cardiac index which fell slightly but significantly in the angina group.There were no differences in myocardial oxygen extraction either within each group or between groups. In the angina group, however, 14 of 20 subjects exhibited abnormal myocardial lactate metabolism during pacing. The mean change was highly significant (P< 0.01). In the nonangina group, eight of 21 subjects had abnormal lactate metabolism during pacing and the mean change was significant (P< 0.05). There was no correlation between abnormal lactate metabolism and electrocardiographic evidence of myocardial ischemia in either group. Sublingual nitroglycerin, given to five subjects with angina while pacing was continued, resulted in prompt relief of symptoms, but abnormal lactate metabolism and ST-segment depression were unaffected after 10 min. By contrast, when anginal symptoms were relieved in five subjects by cessation of pacing, symptomatic improvement was accompanied by marked improvement in lactate metabolism after 10 min. Although angina pectoris appears to be related statistically to subnormal left ventricular function and abnormal lactate metabolism, there is significant individual variation.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

In nine patients with coronary artery disease, cardiac output distribution was evaluated at rest and during exercise by measurement of cardiac output and regional blood flow parameters (hepatic and muscle blood flow). In seven patients repeated values were obtained after a physical training program of 4 to 10 weeks' duration. After training, cardiac output was reduced at moderate work loads (13.1%) causing a change of the relation between oxygen uptake and cardiac output from hyperkinetic to normal. During heavy exercise the cardiac output was increased (5.5%) after training. Similar changes were observed in muscle blood flow, which was reduced at submaximal loads (14.9%) and increased at maximal (8.6%). Hepatic blood flow showed in contrast a less pronounced reduction at both work loads after training (difference, 7.2%). These effects of training could be explained as peripheral regulatory alterations without implying primary improvement in myocardial performance. They are consistent with the view that local changes in the trained muscles are important for the reduction in myocardial pressure-work caused by physical conditioning.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Our results, based on the definition of coronary heart disease by cinearteriography, show that definite relationships exist among incidence of coronary heart disease (CHD), age, total cholesterol (TC), and total triglycerides, with less definite ones between free cholesterol, and phospholipids for a specific group of 450 male patients referred to the Cleveland Clinic because of suspected coronary heart disease. Equations and graphs of the association of incidence of CHD with these conditions are presented. The relationships were strong enough to be of aid in discriminating CHD from normal; the most useful being age, TC, and TG.Incidence determinations were presented in terms of total incidence and incidence associated with the variable itself. Coronary angiography demonstrated 350 CHD and 100 normals or a ratio of 3.5 to 1. This ratio is a reflection of the high accuracy with which physicians suspect CHD.Age and TC were good discriminators in these patients suspected of CHD. An improved relationship and better discrimination was obtained by relating incidence simultaneously to age, TC, and TG. The probability of having CHD is the total incidence corresponding to the patient's age, TC, and TG. The probability level of 0.90 gave 95% assurance of a correct prediction for the physician-selected group of patients. Twenty-nine per cent of them had probabilities above 0.90.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

Of a group of 723 men less than 40 years old who underwent cinecoronary arteriography primarily for evaluation of chest pain, 357 (49%) were found to have at least 50% narrowing of one or more coronary arteries. The youngest person was 17 years old.The distribution of lesions in the young men was similar to that found earlier in a study of persons not selected by age. The anterior descending coronary artery was most frequently affected; the right coronary artery was most often totally occluded. No total occlusions of the left main coronary artery were seen.Electrocardiographic evidence of myocardial infarction, found in 109 patients, was less common with disease of the circumflex or right coronary arteries than with disease of the anterior descending coronary artery. This observation was confirmed by examination of left ventriculograms for areas of decreased contractility. Six patients had no significant arterial narrowing.The extent of arterial involvement seemed to be related to the duration of symptoms in patients who had angina pectoris or myocardial infarctions.Clinical diagnoses correlated well with the angiographic findings, particularly in those men considered to be normal and those with typical angina pectoris. Addition of atypical features or prolonged pain decreased the degree of correlation.Only 20% of those with cholesterol levels less than 200 mg/100 ml had significant lesions, whereas 81% with levels more than 275 mg/100 ml had such findings.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

The atria of 37 patients were paced from selected sites during cardiac surgery. When the atria were paced from endocardial sites low in the right atrium, the P waves in ECG leads II, III, and aVFwere shown to be either negative, biphasic, or positive, depending on the site paced. When the endocardial sites were paced, the P-R intervals were, almost without exception, less than 0.12 sec. When those endocardial sites closest to the A-V junction were paced, the P-R intervals were always less than 0.12 sec. When the atria were paced, from the epicardial sites, the P-R intervals were always greater than 0.12 sec. Negative P waves in ECG leads II, III, and aVFwere recorded when the atria were paced from the postero-inferior left atrium and the caudal right atrium. The P-R interval did not always reflect the initial period of atrial activation because an isoelectric interval, generally of 0.01 to 0.025 sec, was frequently present between the onset of atrial stimulation and the first clear evidence of the P wave in the ECG. The implications of these results are discussed.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID

摘要:

In six successive patients, none of whom had the Wolff-Parkinson-White syndrome, recurrent episodes of paroxysmal supraventricular tachycardia (SVT) were analyzed to determine the mechanism by which this arrhythmia is initiated and sustained. In each patient, simultaneous intracavitary atrial electrograms and surface electrocardiograms were recorded during the onset of numerous spontaneous episodes of SVT. Atrial premature depolarizations (APD) produced by programmed stimulation sequences were used to measure atrioventricular refractory periods and to produce atrial echoes and episodes of SVT. Stimulated APDs introduced during sustained episodes of SVT either altered its behavior or terminated it. The electrophysiologic behavior of SVT in these patients strongly suggests that the mechanism responsible for paroxysmal supraventricular tachycardia is atrial reentry utilizing the A-V conducting system.

ISSN:0009-7322    

出版商:OVID    

年代:1970

数据来源: OVID