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

This 52-year old female patient suffered from exertional dyspnea, fatigue and palpitations progressive for some months. She had rheumatic fever in childhood. Physical examination and echocardiography revealed severe pure mitral regurgitation, invasive studies showed dilatation of the left atrium and ventricle, a regurgitant volume of 70% of the stroke volume and mitral valve replacement was performed.
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PMID:[Exertional dyspnea, fatigue, palpitations]. 291 57

Behavioral, physiologic and exertional fatigue is differently defined, though symptoms are similar. The beneficial effect of amantadine on fatiguability in multiple sclerosis is accompanied by neuropeptide and lactate changes in the circulation. Exercise sometimes overwhelms temperature regulating mechanisms and may be associated with heat stroke. Endogenous opioids are markedly increased in the circulation during heat stroke and the use of specific opioid antagonists therapeutically has been proposed for heat stroke. Sympathetic activity changes in endurance trained subjects and vasoconstrictor responses are markedly attenuated. Similar changes occur in parasympathetic function which can be abnormal in up to 90% of endurance trained subjects. Hormonal secretion during prolonged exertion is altered and the normal signals (inhibiting or activating feedback mechanisms) are different in endurance trained subjects. Altitude, associated with acute mountain sickness, is also accompanied by an increase in cranial bloodflow. Circadian and temporal variation in autonomic function are manifest by changes in mast cell numbers and 5-HT containing nerve fibers in temple skin of patients with cluster headache. The remission rate induced by vagal stimulation in subjects with intractable hiccups is also affected by circadian hormonal or neurogenic influences.
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PMID:The autonomic nervous system and fatigue. 296 78

Dilated cardiomyopathy, owing to any cause, usually culminates in the clinical syndrome of congestive heart failure. Heart failure is characterized by exertional dyspnea and fatigue, but the precise mechanisms that produce these symptoms are still not clear. Sodium retention occurs early in heart failure, but this disturbance is dynamic in nature and is not always present in the patient. The mechanism of early salt and water retention in heart failure is not defined. Gross edema and ascites occur much later, undoubtedly owing to the convergence of a number of factors. The peripheral adaptations to heart failure include activation of the renin-angiotensin system and the sympathetic nervous system, and the release of AVP. The result is an increase in preload with a resultant increase in stroke volume for some patients, but the price is paid in the form of heightened impedance to ejection and circulatory congestion. The sympathetic nervous system disturbances in heart failure are striking, as disturbances in both circulating and myocardial NE levels are consistently found. Vasorelaxant and natriuretic hormones, as well as certain prostaglandins, may be released in an attempt to offset excessive "compensatory" pressor-sodium retentive mechanisms, but the net result seems to be excessive peripheral vasoconstriction and a downward spiral of deterioration in many patients. One would hope that an unraveling of the complex pathophysiology of heart failure would lead to therapy that would change the natural history of the disease. The results of the first V-HeFT trial give room for cautious optimism in this regard.
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PMID:Pathophysiology of congestive heart failure secondary to congestive and ischemic cardiomyopathy. 304 87

In our approach to dynamic cardiomyoplasty, which consists of wrapping a skeletal muscle around the heart and stimulating the former in synchrony with heart contractions to augment ventricular contractility, we have transferred a latissimus dorsi muscle flap to the heart by way of a partial resection of the second rib and subsequently suturing the muscle flap around the ventricles. The muscle flap is stimulated by a Cardio-Myostimulator burst-pulse generator (Medtronic SP 1005) connected to intramuscular electrodes. In preclinical animal research, the latissimus dorsi muscle flap was shown to maintain adequate contractile force and to increase its fatigue resistance by gradual conversion of glycolytic-fatigue-sensitive-to-oxidative-fatigue-resistant muscular fibers (100%). Histochemical and biochemical studies of chronically stimulated muscles showed a total transformation of muscle fast myosin to slow myosin with characteristics similar to those of myocardium. Electron microscopy showed preserved myofibrillar cytoarchitecture and increased mitochondrial density in the cell. At 9 months, cardiac output and ultrasonic Doppler studies showed a significant increase in ventricular function (cardiac output, +21%; peak blood velocity, +40% -80%; and stroke volume, +98% -102%) during muscle stimulation. In the clinical situation, long-term (range of follow-up interval, 4-42 months) beneficial cardiac effects of cardiomyoplasty have been documented in eight patients with various pathologies (ventricular tumor, left ventricular aneurysm, ischemic disease, and dilated cardiomyopathy). Our current understanding of this process is that dynamic cardiomyoplasty acts in two ways: 1) it promotes more vigorous systolic contraction, and 2) it appears to limit heart dilatation.
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PMID:Effect of latissimus dorsi dynamic cardiomyoplasty on ventricular function. 318 Apr

Dynamic cardiomyoplasty involves the use of an electrically stimulated skeletal muscle wrapped around part of the heart to restore or augment myocardial contractility. In our approach, a Latissimus Dorsi muscle flap (LDMF) is transferred to the heart via a partial resection of the second rib, and sutured around the ventricles. The muscle flap is stimulated in synchrony with the heart contractions with bursts of impulses delivered by a "Cardio-Myostimulator" implantable pulse generator via intramuscular electrodes. The object of this study was to identify features of muscle stimulation and to measure the efficacy of L.D. cardiomyoplasty in increasing cardiac output, using an ultrasonic Doppler technique. This report shows the results obtained for goats in which such procedures were performed. Ultrasonic measurements were recorded at the time of cardiomyoplasty and 3-6 months later, during which period the muscle was put progressively into use by slowly increasing the burst frequency content, number of pulses as well as the heart-muscle contraction ratio (3:1, 2:1, 1:1). This postoperative muscle stimulation protocol takes into account the delay of gradual conversion of fast-twitch glycolytic muscular fibers into slow-twitch oxidative, fatigue-resistant fibers, as well as the healing time after cardiomyoplasty required for the muscle flap to recover collateral blood circulation and to adhere to the heart. Results show that synchronous burst stimulation of the muscle flap increases the blood peak velocity in the descending aorta (+36 +/- 8%) and increases the left ventricular stroke volume (+70 +/- 14%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dynamic cardiomyoplasty: a surgical approach for ventricular assistance. 320 74

The study is a retrospective analysis of the clinical features of 122 patients from Finland, whose serum showed in immunoelectrophoresis (IEP) a cathodic elongation of the albumin line, "tailing albumin" (TA), not associated with an M-component. One hundred and seventeen of these cases were found among about 40,000 consecutive routine serum IEP examinations in two laboratories during 1967-1980. Five further cases were detected during the collection of the control series. Only a few TA cases of corresponding type have been reported from elsewhere. Previous studies of some of the patients of the present series had shown that the TA phenomenon was due to complexes between albumin and IgG class autoantibodies against albumin. Clinical data were collected mainly from the hospital records. The chest radiographic findings were classified by the ILO (International Labour Office) method. The author herself examined 33 of the patients during the current disease or during the follow-up. One hundred and ten patients were followed up for a period of three months to nine years (mean 2.5 years). The patients were mostly elderly, and 93% of them were women. Most of the patients had one or more previously diagnosed chronic illnesses, for which they were receiving one or several drugs as long-term therapy. Eighty percent of the patients were receiving nitrofurantoin (NF) as prophylaxis for recurrent urinary tract infections. However, urinary tract infection was not a current problem in any of the cases. There was evidence of a role of NF in the development of both the immunologic abnormalities and the clinical disease in the TA patients. On the basis of long-term NF treatment the patients were divided into two groups: 1) 97 patients with NF therapy (NF+ group) and 2) 25 patients without NF therapy (NF- group). The patients had mostly undergone the examinations because of cough, dyspnoea, and general symptoms (fatigue, weakness, malaise, loss of weight). The symptoms had usually started insidiously, and in 50% of the patients they had lasted for at least three months. Eight of the patients had been hospitalized because of various acute diseases (e.g. cerebral stroke). Ten of the patients were subjectively symptomless. The most common pathologic laboratory findings were high erythrocyte sedimentation rate (over 100 mm/h in 47%), IgG class antinuclear antibodies (in 88%; the titre was greater than or equal to 1000 in 56%), high serum IgG (mean 30.6 g/l), and elevated levels of serum aminotransferases (in 54% of the patients examined).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Immunoelectrophoretic tailing albumin phenomenon. Associations with clinical characteristics of the patients and with nitrofurantoin treatment. 320 74

The purpose of this investigation was to determine the effects of caffeine ingestion on maximal power output and fatigue during short term, high intensity exercise. Nine adult males performed 15 s maximal exercise bouts 60 min after ingestion of caffeine (7 mg.kg-1) or placebo. Exercise bouts were carried out on a modified cycle ergometer which allowed power output to be computed for each one-half pedal stroke via microcomputer. Peak power output under caffeine conditions was not significantly different from that obtained following placebo ingestion. Similarly, time to peak power, total work, power fatigue index and power fatigue rate did not differ significantly between caffeine and placebo conditions. These results suggest that caffeine ingestion does not increase one's maximal ability to generate power. Further, caffeine does not alter the rate or magnitude of fatigue during high intensity, dynamic exercise.
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PMID:Caffeine, maximal power output and fatigue. 322 80

The purpose of this study was to investigate, in a sample of patients with hemiparesis secondary to cerebrovascular accident, the relationship between the ratio of stimulus on time to off time and muscle fatigue using a commercial electrical stimulation unit. An experimental model was used to test the hypothesis that the smaller the stimulus off time relative to stimulus on time, the greater will be the muscle fatigue over time. The wrist extensor muscles of 18 patients with hemiparesis were stimulated electrically, and isometric force output was recorded continuously using an adapted strain gauge-recorder apparatus. For each testing session, peak on time of the electrical stimulus was set at 5 seconds, and off time was set at 5, 15, or 25 seconds. Six randomly assigned treatment groups participated in three separate treatment sessions in a different order at 48-hour intervals. Treatment sessions were continued either until wrist extensor muscle force output decreased to 50% of its initial value or for a maximum of 30 minutes. Data analysis revealed that significant differences in muscle tension developed among all duty cycles (p less than .01). Duty-cycle ratios of 1:1, 1:3, and 1:5 were shown to be progressively less fatiguing. Within the limits of this investigation, the 1:5 duty-cycle ratio was determined to be the best suited for initial use in programs of prolonged stimulation to the wrist extensor muscles of patients with hemiparesis. The hypothesis was accepted that the smaller the stimulus off time (rest interval) with respect to the stimulus on time, the greater will be the muscle fatigue over time.
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PMID:Relationship between functional electrical stimulation duty cycle and fatigue in wrist extensor muscles of patients with hemiparesis. 325

The effects of regular aerobic exercise are important to an aging society increasingly preoccupied with exercise. Traditionally, most attention has been directed to the relationship between a physically active life-style and cardiovascular mortality. In an aging society, however, active life expectancy and maintenance of independence may be as important as effects of regular exercise on longevity. Regular exercise results in increased maximum aerobic capacity due to peripheral changes in muscle (increased capacity for aerobic metabolism and improved substrate and oxygen extraction with a widened arteriovenous oxygen difference) and also due to cardiovascular changes with increased stroke volume and cardiac output in normal persons. "Therapeutic benefits" of conditioning probably occur at submaximal work loads common to everyday activity, when cardiac work and myocardial oxygen consumption are less for any given work load, muscles are more efficient, and relative oxygen requirements are less. Aging is associated with a linear decline in maximum aerobic capacity. The rate of decline is twofold greater when comparing sedentary with physically active middle-aged men. Thus, regular exercise could conceivably lower functional aerobic age by slowing this functional decline. Exercise, particularly excessive exercise, is also associated with serious hazards, including sudden death, nonfatal myocardial infarction, excessive fatigue, hyperthermia, and significant musculoskeletal problems. Accounts of the health effects of exercise should consider a wide range of risks and benefits, especially those related to improving function, minimizing disability, and prolonging independent living.
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PMID:Health benefits of exercise in an aging society. 354 19

Eight physically trained and eight untrained, unacclimated men walked on a treadmill at 30% of their maximum oxygen consumption up to 3.5 h in a thermoneutral [20 degrees C/40% relative humidity (RH)], a warm humid (30 degrees C/80% RH), and a hot dry (40 degrees C/20% RH) environment while wearing industrial work clothing. Their oxygen consumption, rectal and skin temperatures, sweating, cardiac output, heart rate, stroke volume, and peripheral blood pressure were measured during the tests. Thirteen of the 32 heat stress tests were prematurely stopped due to high rectal temperature, high heart rate, subjective fatigue, or heat syncope. The physiological strain, as indicated by the rectal temperature and heart rate, was not significantly different between the warm humid and hot dry environments (wet bulb globe temperature approximately 28 degrees C). The rectal temperature and heart rate responses of the physically trained and untrained subjects did not differ in any of the environments. In the heat, the heart rate was significantly higher than in the thermoneutral environment, but because of the markedly reduced stroke volume the average cardiac output was not different between the three environments. The impaired work performance in the heat seemed mainly to be related to the circulatory instability accompanying the increased cutaneous circulation.
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PMID:Circulatory and thermal responses of men with different training status to prolonged physical work in dry and humid heat. 357 43


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