摘要:

A review of mechanical cardiopulmonary interactions is presented and some extrapolations are made concerning cardiopulmonary resuscitation, with the following conclusions: (1) The cardiac fossa of the lungs provides a soft heart bed at normal lung volumes, but tenses at higher volumes to improve the support of the heart during postural changes. (2) The cardiac fossa is a physiologic constraint at normal heart volumes. It acts to restrict ventricular expansion before there is pericardial restriction. The physiologically useful interventricular interdependence is thereby promoted. (3) The effect of lung inflation in tensing the walls of the fossa may also sometimes embarrass both ventricles. Together with the raised intrathoracic pressure, it is responsible for the fall in left and right ventricular volumes and output during positive pressure ventilation. (4) New techniques of cardiopulmonary resuscitation depend on repeated, abrupt increases in pressure in both chest and abdomen, as in coughing.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Although,β-adrenergic blocking agents reduce myocardial oxygen consumption and symptoms of myocardial ischemia in patients with coronary artery disease (CAD), propranolol has been reported to exacerbate coronary artery spasm in some patients with variant angina. To determine whether increased coronary vasomotor tone can be induced by β-adrenergic blockade, we measured the changes in coronary vascular resistance (CVR) during cold pressor testing (CPT) in 15 patients, nine with severe CAD and six with normal left coronary anatomy, before and after i.v. propranolol (0.1 mg/kg). Coronary blood flow was measured by coronary sinus thermodilution. CVR was calculated as mean arterial pressure divided by coronary sinus blood flow. Heart rate was maintained constant at a paced subanginal rate of 95 ± 5 beats/min.Before propranolol, CPT induced significant increases in coronary vascular resistance in patients with CAD (15.0 ± 2.2%, p < 0.02), but no increase in CVR in the normal patients. After propranolol, the CVR change during CPT was augmented for patients with CAD (29 ± 6%, p < 0.01) and for the normal population (9 ± 5%, NS). The potentiated increase in CVR occurred without significant changes in resting CVR or in the magnitude of the hypertensive response to CPT.We conclude that,β-adrenergic blockade with propranolol can potentiate coronary artery vasoconstriction in some patients with CAD, possibly mediated by unopposed α-adrenergic vasomotor tone. These changes may be important in patients in whom intense adrenergic stimulation may increase coronary artery tone and adversely influence the balance between myocardial oxygen supply and demand.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Cold pressor stimulation (CPS) was compared with supine bicycle exercise during radionuclide ventriculography as a procedure for diagnosing coronary artery disease (CAD). Thirty patients were studied. In the 18 patients with angiographically proved CAD, left ventricular ejection fraction (LVEF) decreased a mean of 5.0 ± 1.0 ejection fraction units (± SEM) in response to CPS. Only two patients developed a new wall motion abnormality. In response to maximal supine exercise, the CAD group showed a mean decrease in LVEF from rest of 1.9 ± 1.1%. Nine patients developed an exercise-induced wall motion abnormality.In the 12 patients with angiographically proved normal coronary arteries, LVEF decreased a mean of 5.8 ± 1.3 units in response to CPS and increased a mean of 9.2 ± 1.2% in response to exercise. Thus, the LVEF response to CPS was not significantly different in the CAD and normal groups (5.0 ± 1.0 vs 5.8 1.3, NS). These same patients demonstrated the expected difference in LVEF response to exercise. We conclude that CPS produces similar changes in LVEF in patients with and without CAD, and therefore is not useful in diagnosing ischemic heart disease.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The purpose of this study was to determine whether 12 months of intense endurance exercise training can induce an increase in left ventricular stroke volume and in stroke work during exercise in patients with coronary artery disease. Eleven male patients were studied. With training, mean maximal oxygen uptake capacity (Vo2max) increased 39%, from 1.85 ± 0.36 to 2.57 ± 0.43 1/min. Stroke volume during upright exercise that required 35–65% of Vo2max was 18% higher after training. At the same percentage of Vo2max, mean blood pressure was the same before and after training; as a result, left ventricular stroke work (mean blood pressure x stroke volume) increased 18% (p < 0.01). These findings suggest that in patients with coronary artery disease, prolonged, intense training induces an increase in stroke volume, and this is a result of cardiac rather than peripheral adaptations.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The effects of intracoronary verapamil and nitroglycerin on collateral blood flow were compared under conditions where coronary perfusion pressure was held constant with a servopump and the systemic effects of the drugs were minimal. Both drugs were infused into 12 anesthetized dogs after occlusion of the left anterior descending coronary artery (LAD) and regional myocardial blood flow (MBF) was measured using microspheres. Before the LAD occlusion, the myocardium not perfused by the LAD was labeled to permit calculation of the fraction of tissue normally perfused in the LAD samples and corrections for collateral flow. The central ischemic zone contained 2.5 ± 0.3% normally perfused myocardium and a 4-mm border zone contained 26.8 ± 4.3% normal myocardium. This border zone contained 10% of the total tissue supplied by the LAD. The MBF in the central ischemic zone increased from 0.101 ± 0.019 to 0.113 ± 0.022 ml/min/g after verapamil infusion (NS) and to 0.149 ± 0.024 ml/min/g after nitroglycerin (p < 0.01). Uncorrected MBF in the border zone increased significantly after infusion of both verapamil (0.469 ± 0.085 ml/min/g, p < 0.01) and nitroglycerin (0.398 ± 0.056, p < 0.05). When corrections were made for interdigitating normal tissue in the border zone, only the MBF after nitroglycerin was significantly increased. Thus, nitroglycerin significantly increased the collateral blood flow to ischemic tissue in the central ischemic and border zones, but verapamil did not.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

The accuracy of rest and exercise radionuclide angiocardiography (RNA) and exercise treadmill testing (ETT) for diagnosis of three-vessel or left main coronary artery disease (extensive CAD) was determined in 544 patients. ETT and RNA sensitivities were similar (88% vs 92%, NS), but ETT was more specific than RNA (46% vs 34%, p < 0.01). The prevalence of extensive CAD in patients with a positive treadmill (41 %) increased only 3% when the RNA was also positive. However, in the 292 patients with a negative or indeterminate ETT, a positive RNA increased this prevalence from 16% to 23%, while a negative RNA decreased this prevalence to 5%. These results support the initial use of ETT followed by RNA if the treadmill is negative or indeterminate for diagnosis in a population with a high prevalence of extensive CAD. This approach separates patients into subgroups with a high or low probability of extensive CAD.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Two-dimensional echocardiography (2-D echo) was performed in 73 patients evaluated for coronary artery disease (CAD) and in four normal volunteers before and immediately after a maximal treadmill exercise test. Diagnostic images were obtained from the apical and parasternal windows. In 17 patients with normal coronary arteriograms, ejection fraction (EF) increased from 66 9% (±4 SD) at rest to 73 8% after exercise (p < 0.001), while in 56 patients with proved CAD, EF fell from 56 13% at rest to 53 16% after exercise (p < 0.01). The sensitivity of postexercise 2-D echo for detecting CAD (based on abnormal EF response and/or regional dyssynergy) was 91% (51 of 56 patients) and the specificity was 88% (15 of 17). Sensitivity for one-, two- and three-vessel disease was 64% (seven of 11), 95% (20 of 21) and 100%, respectively. Patients with multivessel disease showed a significant fall in a wall motion score index, from 0.79 0.25 to 0.63 0.26. Exercise radionuclide ventriculography (RNV) was also performed in 41 of the subjects (17 normals and 24 CAD patients) on a bicycle ergometer. The overall sensitivity of 2-D echo in this subgroup was 92%, compared with 71% for RNV. The sensitivity of 2-D echo for one-vessel disease (n = 4) was 50%, that for two-vessel disease (n = 12) was 100% and that for three-vessel disease (n = 12) was 100%. Respective values for RNV were 0%, 80% and 90%. The specificity of 2-D echo was 88% and that of RNV was 82%. A significantly higher peak heart rate response was observed on the treadmill than on the bicycle ergometer in both CAD patients and normal subjects. We conclude that postexercise 2-D echo is a clinically applicable technique for the diagnosis and evaluation of CAD patients and compares favorably with exercise RNV.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID

摘要:

Ten patients (six women and four men) with endomyocardial disease, four with and six without hypereosinophilia, were studied by two-dimensional echocardiography (2-D echo). Eight had biventricular congestive heart failure and two had atypical chest pain with ischemic electrocardiographic changes. The patients were 15–50 years old (mean 40 years) and duration of illness was 2–9 years (mean 4.4 years). Nine had cardiac catheterization and three pathologic examination. Characteristic 2-D echo findings included apical obliteration of one or both ventricles by echogenic material suggestive of fibrosis or thrombosis; bright, specular echoes at the cavity surface of the apical obliteration suggesting patchy calcification; preserved left apical systolic inward motion, which differed significantly from the dyskinetic motion of thrombotic apical obliteration of ischemic or Chagasic origin (p < 0.001); involvement of the papillary muscles and posterior atrioventricular valve; preserved ventricular contractile function in most patients; and the combination of normal-to-small ventricles with large atria. None of 14 subjects with secondary hypereosinophilia followed for 15.4 months developed similar 2-D echo findings. We conclude that both forms of endomyocardial disease had a 2-D echo pattern useful for noninvasive recognition and differentiation from patients who have valvular heart disease, constrictive pericarditis and cardiomyopathies of other origins.

ISSN:0009-7322    

出版商:OVID    

年代:1983

数据来源: OVID