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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied contractile property and fatigue rates of skeletal muscle ventricle (SMV) constructed using the latissimus dorsi muscles of 11 dogs. The role of early interruption of collateral blood supply in the prevention of muscle ischemia and SMV fatigue was evaluated. Systolic function of SMV was measured in a hydraulic test system; afterload was set at 70 mmHg and preload 15 or 25 mmHg. Control SMV (GI: N = 7), which was fashioned immediately after interruption of collateral blood supply, generated an initial SMV pressure of 222 +/- 50 mmHg and stroke volume of 15 +/- 7 ml/beat with muscle stimulation at a burst-frequency of 50 Hz, but could sustain flow for only 3.5 +/- 0.8 minutes. SMV subjected to a vascular delay (Group II: N = 4) demonstrated improvement of fatigue rates; duration of flow 32.4 +/- 14.0 and sufficient contractile property (initial SMV pressure 182 +/- 17 mmHg, stroke volume 1- +/- 2 ml/beat). Thermography surface temperature mapping revealed remarkable improvement of blood distribution in GII muscles. Flow rates of thoracodorsal artery were significantly greater in GII muscles compared to those in GI muscles (15.0 +/- 3.7 ml/min/LD 100 g, 10.1 +/- 3.1 ml/min/LD 100 g, p less than 0.05, respectively). Despite significant improvement of functional durability in GII muscles, the ratio of oxygen consumption to lactate output was not different between 2 groups. These results suggest that early interruption of collateral blood supply can minimize muscle ischemia, resulting in diminishing fatigue of latissimus dorsi muscles without changes in skeletal muscle metabolism.
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PMID:[Experimental study on potential for cardiac assist by latissimus dorsi myograft--an importance of muscle ischemia]. 205 Oct 84

In order to evaluate the possibility of left ventricular assistance by latissimus dorsi (LD) myograft, we have studied contractile property and fatigue rates of skeletal muscle ventricle (SMV) constructed using canine LD muscles. Twenty three dogs were divided into 3 groups depending on the conditioning protocol of LD muscles; Group I (Control n = 12), Group II (Vascular delay n = 4) and Group III (Vascular delay and electrical preconditioning n = 7). SMVs in GIII dogs generated sufficient pressure and forward flow in a hydraulic test system with muscle stimulation at a burst-frequency of 50 Hz (SMV pressure 131 +/- 42 mmHg, Stroke volume 7.0 +/- 3.0 ml/beat). Although SMVs in GI and GII dogs could sustain flow for only 4.0 +/- 1.1 minutes and 32.4 +/- 14.0 minutes, respectively, SMVs in GIII were able to pump continuously for 107.5 +/- 15.0 minutes (p less than 0.01, vs GI and GII). Thermography surface temperature mapping revealed marked improvement of blood distribution of LD muscles in GII and GIII dogs. Flow rates of thoracodorsal artery during SMV stimulation were GI: 10.0 +/- 3.1 ml/minute/LD 100 g, GII: 15.0 +/- 3.7 ml/minutes/100 g and GIII: 20.7 +/- 2.5 ml/minutes/100 g (p less than 0.01 vs GI). The ratio of oxygen consumption to lactate output was GI: 0.33 +/- 0.10, GII: 0.36 +/- 0.09 and GIII: 1.56 +/- 0.97 (p less than 0.01 vs GI, p less than 0.05 vs GII). Histochemical examination of LD muscles using alkaline ATPase stain revealed muscle fiber type transformation of GIII muscles. These results suggest electrically preconditioned LD muscles have sufficient contractile property for partial left ventricular assistance, and highly fatigue-resistant properties resulted from muscle fiber transformation, improved muscle perfusion and metabolic changes.
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PMID:[Potential for left ventricular assistance by latissimus dorsi myograft--sequential effects of electrical preconditioning on skeletal muscle fiber type, blood flow and metabolic status]. 205 Oct 85

The purposes of this study were three-fold: (a) to determine acute physiologic responses of spinal cord injured (SCI) subjects to peak levels of leg cycle ergometry utilizing functional neuromuscular stimulation (FNS) of paralyzed leg muscles, (b) to determine the relative contributions of passive and active components of FNS cycling to the peak physiologic responses, and (c) to compare these physiologic responses between persons who have quadriplegia and those who have paraplegia. Thirty SCI subjects (17 quadriplegics and 13 paraplegics) performed a discontinuous graded FNS exercise test from rest to fatigue on an ERGYS 1 ergometer. Steady-state physiologic responses were determined by open-circuit spirometry, impedance cardiography with ECG, and auscultation. In the combined statistics of both groups, it was noted that peak FNS cycling significantly increased (from rest levels) mean oxygen uptake by 255%, arteriovenous O2 difference VO2 and VE, Q and a-vO2 and VCO by 69%, and stroke volume by 45%, while total peripheral vascular resistance decreased by 43%. Mean peak power output for paraplegics (15 W) was significantly higher than for quadriplegics (9 W), eliciting higher peak levels of pulmonary ventilation and sympathetically mediated hemodynamic responses such as cardiac output, heart rate, and systolic and diastolic arterial blood pressure. Passive cycling without FNS produced no statistically significant increases in physiologic responses above the resting level in either group.
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PMID:Physiologic responses of paraplegics and quadriplegics to passive and active leg cycle ergometry. 223 Jul 94

A clinical study was made on depressive state following stroke using stroke patients in the chronic stage. There were 118 stroke patients in the present study and 25 patients (21.2%) satisfied the diagnostic criteria for major depressive syndrome of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition Revised (DSM-III-R). As for dispositional, social, and somatic factors, a tendency was observed for depressive state to develop at a high frequency among patients with a past history of mental disorder prior to development of stroke, patients residing in suburban area, patients engaged in domestic and agricultural work, and patients with a frequent history of physical disorders. A tendency was observed for depressive state to develop at a high frequency among patients showing B type in YG test and patients presenting laterality in electroencephalography. Among the 49 right stroke patients, depressive state was observed in 10 cases (20.4%), while among the 43 left stroke patients, depressive state was seen in 10 cases (23.2%) with the incidence of depressive state showing no difference by hemisphere stroke. Study of the clinical characteristics of depressive state by hemisphere stroke with the use of symptom items of Zung scale and Hamilton scale showed that patients in depressive state with right hemisphere stroke had high values in symptom items considered close to the essence of endogenous depression such as depressed mood, suicide, diurnal variation, loss of weight, and paranoid symptoms, while patients in depressive state with left hemisphere stroke had high values in symptom items having a nuance of so-called neurotic depression such as psychic anxiety, hypochondriasis, and fatigue. Comparison with endogenous depression patients indicated that right stroke patients rather than left stroke patients showed a clinical picture suggestive of endogenous depression. Antidepressant was effective in 71.4% of the cases, but no difference in effectiveness could be observed by hemisphere stroke. In stroke patients in the chronic stage the incidence of clinical depressive state was higher than 20%, and involved in its onset were not only brain organ lesions but also dispositional, social, and somatic factors and integration dysfunction in the emotional activity of the left and right hemisphere functions. As for the clinical picture, a picture considered close to endogenous depression was observed in right stroke patients, while that considered close to so-called neurotic depression was seen in left stroke patients. The therapeutic effect of antidepressant was almost equivalent to that for endogenous depression.
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PMID:[Clinical study on depressive state following stroke]. 223 45

A muscle powered cardiac assist device (MCAD) for right ventricular support requires optimized diastolic filling to obtain full stroke and acceptable fluid dynamics. A valved and spring-assembled skeletal muscle ventricle (SMV) was designed as a prototype MCAD, regardless of fluid dynamics. The present study addresses the optimal bypass method for right ventricular support, and predicts the future design for an implantable MCAD. Latissimus dorsi muscle (LDM) of 11 dogs were conditioned electrically for a one year maximum, and transformed into fatigue-resistant muscles (Type I fibers). Superior and inferior vena cavae were anastomosed using one arm of a Y-shaped vascular graft, as an inflow conduit, and the outflow conduit was placed on the main pulmonary artery. SMV was wrapped with transformed LDM and the bypass method was varied by SVC and/or IVC ligation. SMV demonstrated sufficient right ventricular support on total bypass (70% compared with control output), and the maximum pump off-to-on flow ratio (200%) was obtained. Maximum SMV power output was 0.27 X 10(6) erg, which was equivalent to that of canine right ventricle. Right atrial-to-pulmonary artery bypass was also constructed by using SMV in another 14 dogs, and also showed that total bypass was preferable for optimal SMV diastolic filling. In conclusion, specific requirements for a future MCAD include a subsystem assembly such as a spring, magnet, or alternative auxiliary muscle pump assembly for MCAD filling, and total bypass with optimized fluid dynamics and anatomic fitting.
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PMID:A muscle powered cardiac assist device for right ventricular support: total assist or partial assist? 225 2

Factors contributing to maximal incremental and short-term exercise capacity were measured before and after 12 wk of high-intensity endurance training in 12 old (60-70 yr) and 10 young (20-30 yr) sedentary healthy males. Peak O2 uptake in incremental cycle ergometer exercise increased from 1.60 +/- 0.073 to 2.21 +/- 0.073 (SE) l/min (38% increase) in the old subjects and from 2.54 +/- 0.141 to 3.26 +/- 0.181 l/min (29%) in the young subjects. Peak cardiac output, estimated by extrapolation from a series of submaximal measurements by the CO2 rebreathing method, increased by 30% (from 12.7 to 16.5 l/min) in the old subjects, associated with a 6% increase (from 126 to 135 ml/l) in arteriovenous O2 difference; in the young subjects there were equal 14% increases in both variables (18.0 to 20.5 l/min and 140 to 159 ml/l, respectively). Submaximal mean arterial pressure and cardiac output were lower posttraining in the old subjects; total vascular conductance and cardiac stroke volume increased. Although peak power at the start of a short-term maximal isokinetic test did not change, total work accomplished in 30 s at a pedaling frequency of 110 revolutions/min increased in both groups, from 11.2 to 12.6 kJ and from 15.7 to 16.9 kJ in the old and young, respectively; fatigue during the 30-s test was less, and postexercise plasma lactate concentrations were lower. In older subjects, increases in aerobic power after high-intensity endurance training are at least as large as in younger subjects and are associated with increases in vascular conductance, maximal cardiac output, and stroke volume.
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PMID:High-intensity endurance training in 20- to 30- and 60- to 70-yr-old healthy men. 227 73

Hemodynamic and metabolic changes were measured at rest and during exercise in 23 patients with chronic heart failure and in 6 control subjects. Exercise was limited by leg fatigue in both groups and capacity was 40% lower in the patients with failure. At rest, comparing patients with control subjects, heart rate and right atrial and pulmonary wedge pressure were higher; cardiac output, stroke volume and work indexes and ejection fraction were lower; mean arterial and right atrial pressure and systemic resistance were similar. During all phases of exercise in patients with heart failure, pulmonary wedge pressure and systemic vascular resistance were higher and pulmonary vascular resistance remained markedly elevated compared with values in control subjects. Cardiac output was lower in the patients with failure, but appeared to have the same physiologic distribution in both groups during exercise. Although arterial-femoral venous oxygen content difference was higher in patients with heart failure, this increase did not compensate for the reduced blood flow. Even though the maximal oxygen consumption was significantly reduced, femoral venous lactate and pH values were higher than values in control subjects, but femoral venous pH was similar in both groups at their respective levels of maximal exercise. Ejection fraction was lower in those with heart failure at rest and did not increase with exercise. Ventilation in relation to oxygen consumption was higher in patients with failure than in control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hemodynamic and metabolic basis of impaired exercise tolerance in patients with severe left ventricular dysfunction. 231 88

The long-term prognosis and quality of life of 201 patients admitted to hospital with reversible ischemic attacks (RIA) were estimated in a prospective study. The median follow-up time was 58 months. Further RIAs were reported by 91 patients (45%) and 48 (24%) suffered a stroke. The risk of stroke was markedly higher in the first 6 months after RIA, after which the annual stroke rate was rather constant with an average of 4.8%, about 8 times higher than expected. The average annual mortality rate for the RIA patients was 5.9%, which is significantly higher than expected. Cardiovascular deaths accounted for more than half of all deaths, stroke for one fourth. Life-table analysis of subgroups disclosed a much more favorable prognosis for women under 60 years. High systolic blood pressure, diabetes, and previous myocardial infarction were identified as risk factors. The occurrence of RIA had significantly influenced the quality of life and occupational status for the majority of the patients, even for those who did not suffer a subsequent stroke. Decreased working capacity, general asthenia and fatigue and impaired memory were the most common complaints. We conclude that RIA may be a more serious vascular event than generally believed. Apart from carrying a substantial risk of stroke and death, even a single RIA can cause permanent psychological dysfunction influencing the quality of life.
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PMID:Long-term prognosis and quality of life after reversible cerebral ischemic attacks. 271 39

beta-Adrenoceptor blockers (beta-blockers) are common first-choice drugs in the treatment of various cardiovascular disorders. Physical exercise performed during single-dose administration of beta-blockers, however, is associated with an increased rate of perceived exertion; an effect which appears to be partly reduced with long term treatment. Although clinical doses of beta-blockade may reduce heart rate by 30 to 35%, during maximal exercise cardiac output is not equally reduced. Accordingly, most studies have demonstrated increased stroke volume after beta-blockade. This reduction in heart rate is typically accompanied by a decreased VO2max (5 to 15%) in both patients and healthy, trained subjects. This smaller reduction in VO2max, as compared with the decrease in cardiac output, is the result of a partly compensating increased arteriovenous O2 difference. Work capacity as reflected by the ability to perform intense short term or more prolonged steady-state exercise is also impaired following beta-blockade. beta-Adrenoceptors can be subdivided into types beta 1- and beta 2. Blockers which are specific for either beta 1-receptors (beta 1-selective blockers) or both beta 1- and beta 2 receptors (non-selective blockers) differ with regard to their effect on exercise performance. Exercise performance ability, irrespective of exercise intensity and duration, is impaired to a greater extent following non-selective than beta 1-selective blockade at equal reductions in heart rate. This response stems from a decreased energy flux through glycogenolysis during non-selective blockade treatment. Individuals receiving beta-blockade medication therefore show greater adaptive response to physical conditioning during treatment with beta 1-selective than non-selective blockade probably because of greater training intensity with the former therapy. Neither psychomotor performance nor muscular strength and power is negatively affected by beta-blockade. Nevertheless, the ability to perform athletic events requiring high levels of motor control under emotional stress but not high levels of aerobic or anaerobic energy release, is probably increased during beta-blockade.
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PMID:Exercise performance and beta-blockade. 286 77

Labetalol is a unique antihypertensive agent which is a competitive peripheral antagonist at both alpha- and beta-adrenoceptor sites. Clinically, it possesses about one fourth of the beta-adrenoceptor blocking activity of propranolol and one half of the alpha-adrenoceptor blocking activity of phentolamine with a beta- to alpha-blocking ratio of approximately 7:1. Nowadays, the clinical profile of labetalol is clearly defined. Perorally, it has often been used in the treatment of mild, moderate and severe hypertension and intravenously in the management of hypertensive emergencies. It offers many advantages over beta-blockers with no prominent side-effects. Hemodynamically, labetalol reduces blood pressure, heart rate and, first of all, peripheral resistance with almost no change in resting cardiac output or stroke volume. Labetalol appears to be useful particularly in patients whose blood pressure is not adequately controlled by beta-blockers alone or combined with a diuretic, but sometimes at the expense of postural hypotensive side-effects. It has proved to be safe in patients with coronary artery disease or after acute myocardial infarction and in pregnant patients, but in phaechromocytoma further clinical experience is needed. In induced hypotension during anesthesia and surgery no invasive blood pressure measurements are needed. The most frequent adverse effects include fatigue, postural hypotension, headache and gastrointestinal complaints. On the whole, labetalol expands the armamentarium of the practising physician in the treatment of hypertension of different origin.
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PMID:Current status of labetalol, the first alpha- and beta-blocking agent. 286 49


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