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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cardiovascular responses have been studied in baboons, after total exchange transfusion with hemoglobin solutions having various P50 values. At the end of the exchange transfusion, the hematocrit was 1.5%, the mean hemoglobin concentration was 4.4 g/dl, and the P50 varied between 12 and 26 mm Hg. Cardiac output did not change during the study, although heart rate increased, and stroke volume and MAP decreased. Hemoglobin concentration, per se, does not appear to be the critical stimulus for an increase in cardiac output with hemoglobin solution. In addition, the position of the hemoglobin-oxygen dissociation curve does not appear to influence these hemodynamic responses. The physiological response to anemia in the presence of hemoglobin solution appears different from that observed in the absence of plasma O2 carriers.
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PMID:Cardiac output response to extreme hemodilution with hemoglobin solutions of various P50 values. 11 94

Cardiac hemodynamics were assessed by right and left heart catheterizations in nine patients on hemodialysis. Results showed increased stroke work index and left ventricular work indices. Left ventricular end-diastolic pressure was elevated in all patients (markedly so in five) and did not fall with occlusion of arteriovenous communications. Cardiac output was significantly elevated, but fell to normal postocclusion. Myocardial oxygen consumption, indirectly assessed by tension time and pressure rate indices, appeared increased. Six patients died: four from complications attributed to myocardial failure without infarction, one from transplant-related complications, and one from bacterial meningitis. Five had increased cardiac weights at autopsy, but none showed infarction. This study suggests that increased cardiac work is present in chronic renal failure. Myocardial mass increases result in increased myocardial oxygen demand; however, the increased oxygen requirements may not be met because of reduced erythrocyte mass. Persistance of pressure-volume overload and severe anemia are conducive to myocardial failure.
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PMID:Cardiac work demands and left ventricular function in end-stage renal disease. 13 18

Left ventricular performance was studied in 23 young patients with severe chronic anemia due to beta-thalassemia major and intermedia. The patients were divided into three groups according to the number of blood transfusions they had received. The left ventricle (LV) was enlarged in patients who had not received blood and larger still in patients who had received multiple transfusions. Echocardiography and systolic time interval measurements showed that systolic function of the LV was good in all the patients and that there was no statistical difference in systolic function in patients who had and those who had not received multiple transfusions. Heart rate was increased in the latter group. Stroke index and cardiac index were high, especially in patients in Group 3. The diastolic closure rate (EF slope) of the anterior mitral leaflet and its amplitude of movement were increased, but less so in Group 3; this may reflect an alteration in diastolic LV distensibility. The results indicate that despite the presence of cardiomegaly and severe clinical congestive heart failure, LV performance is well preserved in patients with beta-thalassemia, even in those who have received repeated blood transfusions. Clinical cardiac failure is the consequence of volume overload and abnormal chamber compliance. There was no evidence in this of a congestive cardiomyopathy.
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PMID:Left ventricular function in beta-thalassemia and the effect of multiple transfusions. 16 23

It is important to establish the diagnosis of temporal arteritis because the disease is treatable; treatment may prevent blindness and even death. Temporal arteritis usually occurs in people older than 51 years of age, although very rarely, histologically documented disease occurs in younger people. The onset may be occult, so that there are few findings. A multitude of signs and symptoms may occur such as fever, headaches, malaise, weight loss, anemia, stroke, cranial nerve palsies, polymyalgia rheumatica, aortitis and other large vessel involvement. The eye may suffer from ischemic optic neuropathy (anterior or posterior), central or cilio-retinal arterial occlusion, ophthalmic artery ischemia, or extraocular muscle palsies. An arterial biopsy showing giant cell arteritis establishes the diagnosis. However, a negative biopsy does not rule out the disease because of the occasional presence of skip areas. Arteriography has only rarely yielded a positive temporal artery biopsy when the initial biopsy done elsewhere was negative. As a diagnostic parameter, the erythrocyte sedimentation rate is nonspecific, being elevated in diseases other than temporal arteritis and sometimes being falsely lowered by technical factors. Furthermore, the temporal artery biopsy is occasionally positive despite a normal erythrocyte sedimentation rate. Treatment is aimed at relieving the patient's symptoms and normalizing the erythrocyte sedimentation rate. Because of the wide spectrum of clinical and laboratory finding in temporal arteritis, no one specific treatment regimen with systemic corticosteroids works for all patients. Temporal arteritis is a well known disease of the elderly which ir rarely fatal but results in significant visual morbidity (Hinzpeter & Naumann, 1976; Spencer & Hoyt, 1960). Since Hutchinson's (1890) description, more than a thousand articles have been written on the subject (Cohen & Smith, 1974). Despite this, many unanswered questions and controversies remain concerning the diagnosis, prognosis and treatment of temporal arteritis. My goal is to review these questions and areas of controversy.
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PMID:Controversies regarding giant cell (temporal, cranial) arteritis. 39 20

Echocardiographic aortic root motion in systole was studied in 57 patients: 13 normal subjects, 4 patients with left ventricular (LV) volume overload due to anaemia, 16 patients with mitral incompetence, 13 with aortic incompetence and 11 with mitral stenosis. In normal subjects, patients with mitral stenosis and in patients with LV volume overload, in whom the increased stroke volume was ejected forwards into the ascending aorta (anaemia, aortic incompetence) the amplitude of motion of the posterior aortic wall (vp), the aortic widening fraction (AWF) and total aortic motion (TAM) were increased. In mitral incompetence, however, despite the large increase in total LV stroke index, there was a decrease in vp (P less than 0.01), AWF (P less than 0.001) and TAM (P less than 0.001), and the decrease in aortic motion for a given stroke index was related to the mitral regurgitant fraction, indicating that aortic wall movement in systole depended predominantly on forward ejection of the LV stroke volume. Reduced echocardiographic aortic root motion and widening during systole are useful echocardiographic signs of mitral regurgitation.
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PMID:Echocardiographic aortic root motion in ventricular volume overload and the effect of mitral incompetence. 51 Mar 47

The integrated response to severe exercise involves fourfold to fivefold increases in cardiac output, which are due primarily to increases in cardiac rate and to a lesser extent to augmentation of stroke volume. The increase in stroke volume is partly due to an increase in end-diastolic cardiac size (Frank-Starling mechanism) and secondarily due to a reduction in end-systolic cardiac size. The full role of the Frank-Starling mechanism is masked by the concomitant tachycardia. The reduction in end-systolic dimensions can be related to increased contractility, mediated by beta adrenergic stimulation. Beta adrenergic blockade prevents the inotropic response, the decrease in end-systolic dimensions, and approximately 50% of the tachycardia of exercise. The enhanced cardiac output is distributed preferentially to the exercising muscles including the heart. Blood flow to the heart increases fourfold to fivefold as well, mainly reflecting the augmented metabolic requirements of the myocardium due to near maximal increases in cardiac rate and contractility. Blood flow to the inactive viscera (e.g., kidney and gastrointestinal tract) is maintained during severe exercise in the normal dog. It is suggested that local autoregulatory mechanisms are responsible for maintained visceral flow in the face of neural and hormonal autonomic drive, which acts to constrict renal and mesenteric vessels and to reduce blood flow. However, in the presence of circulatory impairment, where oxygen delivery to the exercising muscles is impaired as occurs to complete heart block where normal heart rate increases during exercise are prevented, or in congestive right heart failure, where normal stroke volume increases during exercise are impaired, or in the presence of severe anemia, where oxygen-carrying capacity of the blood is limited, visceral blood flows are reduced drastically and blood is diverted to the exercising musculature. Thus,, visceral flow is normally maintained during severe exercise as long as all other compensatory mechanisms remain intact. However, when any other compensatory mechanism is disrupted (even the elimination of splenic reserve in the dog), reduction and diversion of visceral flow occur.
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PMID:Cardiovascular adjustments to exercise: hemodynamics and mechanisms. 79 Apr 60

While differences in acceptability of steroidal contraceptives from nation to nation are generally recognized, variations in safety and effectiveness have been given little attention. Cardiovascular hazards such as thromboembolic disease, myocardial infarction, and stroke, which create such concern in developed countries, may be insignificant problems in other parts of the world where these diseases are rare in women of reproductive age. On the other hand, the influence of nutritional deficiencies, anemia, intestinal parasitism, malaria, and other widespread health problems on the effects and/or metabolism of steroids, which may be of major concern in developing countries, is just coming under study. Side effects also vary greatly among religiously and ethnically different populations, and significant differences in pregnancy protection and bleeding patterns among different populations have been reported-even with injectables. It is, therefore, important to examine and define intergroup differences and especially to recognize that safety concerns in one geographic setting cannot be automatically assumed to apply equally in other areas.
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PMID:Perspectives in evaluating the safety and effectiveness of steroidal contraceptives in different parts of the world. 92 97

A severely anaemic, but asymptomatic patient, who is a heterozygous carrier of haemoglobin Hammersmith (beta42 (CD1) phenylalanine - Serine), has been studied to elucidate the mechanisms resulting in physiological compensation for the anaemia. Four factors have been investigated: the oxygen affinity of her blood, the cardiac output at rest and during exercise, the blood gas indices, and pulmonary function. It was found that due to the presence of Heinz bodies within the erythrocytes, the level of functional, haemoglobin was considerably less (50 g/l) than that measured by standard methods (87 g/l). In addition a moderate degree of arterial hypoxaemia (arterial oxygen tension = 10.7 kPa (80.4 mmHg) was present which could not be explained on the basis of abnormal pulmonary function. Both of these factors would result in tissue hypoxia, but the finding of consistently normal oxygen tensions ('mixed' venous oxygen tension = 5.4 kPa (40.3 mmHg) in blood obtained from the right atrium, suggested that hypoxia was not present. This was explained by a decreased whole blood oxygen affinity (P50 = 4.6 kPa (34.5 mmHg) at pH 7.4) and an increase in the cardiac index (5.3 L.min.-1m-2). The latter was the result of an increased stroke volume (125 - 135 ml), the heart rate being normal (63/min.). During moderate exercise, further increases at cardiac output were brought about by a change in heart rate alone. It has been calculated that the decrease in whole blood oxygen per se could not account for adequate tissue oxygenation. This is confirmed by the finding of an increased cardiac output in this patient. It is suggested that in any severe haemolytic anaemia, even if the whole blood oxygen affinity is low, cardiac output is probably increased to achieve complete physiological compensation.
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PMID:Compensatory mechanisms for the severe anaemia caused by haemoglobin Hammersmith. 93 44

Acute isovolemic anemia was produced in anesthetized chickens by serial exchanges of 6% dextran 70 equal to 1% of body weight to quantitate cardiovascular and metabolic parameters. When hematocrit (Hct) and hemoglobin (Hb) levels were reduced by 50% (from 33.3 to 16.3 vol %, and from 10.3 to 5.4 g/100 g, respectively, P less than 0.001), tissue oxygen delivery was maintained by increases in cardiac output (CO), stroke volume (SV), oxygen extraction, and reduced total peripheral resistance (TPR). Heart rate, right atrial pressure, and oxygen consumption (Vo2) were unchanged. Further reductions in Hct and Hb (to 10.8 vol % and 3.7 g/100 g, respectively), were accompanied by cardiovascular failure, as evidenced by falling CO, SV, tissue oxygen delivery, and Vo2. Relative apparent viscosity determinations on the exchanged blood-dextran mixtures indicated that large viscosity changes occurred with the first exchange whereas subsequent exchanges had small incremental viscosity changes. These data indicate that in acutely anemic chickens, oxygen transport capacity was maintained by increased cardiac output and decreased peripheral resistance, unless the severity of the anemia resulted in cardiovascular failure.
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PMID:Acute isovolemic anemia in anesthetized chickens. 99 89

The energy metabolism and heart rate response to exercise were studied in haemorrhagically anaemic sheep. Anaemia did not affect the efficiency of food utilisation, but might reduce appetite. Anaemic sheep were at no particular circulatory disadvantage under the stress of physical exertion up to the levels imposed in this experiment (3-2km/h, 8 degrees -12 degrees gradient), but they appeared to undergo some circulatory adaptation, probably an increased stroke-volume.
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PMID:The effects of haemorrhagic anaemia and physical training on the energy metabolism and heart rate response to exercise in sheep. 102 37


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