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

Ambulatory ECG monitoring for detection of transient myocardial ischemia is useful because most ischemic episodes that occur outside the exercise laboratory are not accompanied by symptoms. Special considerations, not required for AEM when used for arrhythmia analysis, must be employed. Although many commercially available recorders provide excellent ST-segment reproduction, some playback systems may have a nonlinear phase response resulting in signal distortion, making ST-segment analysis difficult. Conventional Holter-type AEM devices do not allow for patient or physician intervention during acute myocardial ischemia. Considerable cost and time are required to analyze ST-segment data of prolonged monitoring periods from these tape-recorded signals, and human error and fatigue play an important role in diminishing accuracy of ST-segment interpretation. Automated analysis is done with computer and technician interaction but the accuracy and validation of the various systems for ST-segment analysis from tape recordings requires further detailed study. Newer, real-time ambulatory ECG analyzers are designed for prolonged monitoring periods and directed toward ST-segment analysis. Some devices also alert the patient to an acute ischemic or arrhythmic event allowing for intervention immediately. Some real-time systems have undergone some very encouraging validation studies. These recent studies suggest excellent sensitivity and specificity for detection of ischemic-type ST-segment depression. However, more work is needed before the accuracy of other such devices is known with certainty. As the central goal of therapy for patients with coronary artery disease evolves from simply controlling angina to reduction or elimination of ischemic episodes and their consequences, use of AEM devices will play an increasingly important role in management of these patients.
Cardiovasc Clin 1988
PMID:Ambulatory ECG (Holter) monitoring in management of acute myocardial ischemia. 328 67

Strut fracture, with embolization of the disc occluder, caused the death of a 64-year-old man who had a Beall model 105 heart valve prosthesis in the mitral position for 13 years. Scanning electron microscopy of the fractured surface revealed evidence of a fatigue failure mechanism in the metal wire. The case is unique in that strut fractures affecting this prosthesis had only been observed previously in the range of 141 to 342 days after implantation. Morphological changes in this valve prompted reexamination of three other model 105 prostheses that had been recovered from the mitral area at necropsy or surgery 9 to 10 years after insertion in 1972 or 1973. All had been kept in dry storage. The three prostheses and the valve described above showed previously unrecognized cracks in the pyrolytic carbon coating of the struts, which form the cage that limits occluder movement. The defects were located at or near the base of struts, where they entered the sewing ring and were bent to pass into the strut supporting ring. We believe that the cracks in the carbon coating precede total strut fracture and postulate that they are needed for the metal wire to be subject to a fatigue failure mechanism.
J Thorac Cardiovasc Surg 1988 Sep
PMID:Late strut fracture of the Beall model 105 disc valve prosthesis. 341 91

Ruptured sinus Valsalva aneurysm was repaired in 13 patients (mean age c. 33 years). Dyspnea, chest pain, fatigue and palpitation were the most common symptoms and systodiastolic murmur, cardiomegaly and pulmonary congestion the most pertinent clinical findings. The pulmonary-to-systemic flow ratio averaged c. 2.5. Associated cardiac anomalies were ventricular septal defect, aortic or mitral regurgitation, aortic coarctation or subvalvular stenosis, tetralogy of Fallot (altogether 8 cases). The origin of the fistula was the noncoronary, right coronary or left coronary sinus (5, 4 and 3 cases) or was not identifiable (1 case). Rupture occurred into the right atrium (6 cases), right ventricle (6) or pulmonary artery (1 case). Repair was undertaken through aortotomy (6 cases), right ventriculotomy (2) or right atriotomy (1) or through aortotomy + right ventriculotomy or atriotomy (4). In one case aortic valve replacement was performed. All survived the operation. Follow-up averaged 9.6 years. Recurrent fistulation, though with small shunt, was found in two cases. Combined two-dimensional and Doppler echocardiography revealed minor cardiac abnormalities in most patients, particularly aortic regurgitation. All the patients were in NYHA function class I or II.
Scand J Thorac Cardiovasc Surg 1987
PMID:Ruptured aneurysm of sinus of Valsalva. Long-term postoperative follow-up. 343 19

The incidence and extent of cerebral damage following open-heart surgery were prospectively investigated in 103 patients, using clinical assessment, psychometry, adenylate kinase analysis in cerebrospinal fluid (CSF-AK) and computed tomography (CT) of the brain. The surgical mortality was 1.9%. Clinically there was obvious cerebral dysfunction in four cases, subtle evidence of brain damage (mainly undue fatigue) in 16 and no evidence in 81 cases. In the 16 patients the mean CSF-AK was substantially increased (0.122 U/l) and the psychometric performance distinctly impaired (-12 points) postoperatively; in the 81 patients the figures were 0.55 U/l and -3.4. Psychometrically, 60% of the patients showed cerebral dysfunction, which was pronounced in 16%. CSF-AK analysis indicated cerebral damage as absent or trival in 45%, moderate in 33% and marked in 22%. CT revealed postoperative cerebral infarction in two cases. Results from the various methods showed reasonable correlation, but also considerable overlap. Open-heart surgery thus can cause brain damage additional to that neurologically discernible. Fatigue is an important sign in this context. In research on postoperative brain damage, the relative insensitivity of routine neurologic investigation calls for supplementary, refined methods.
Scand J Thorac Cardiovasc Surg 1987
PMID:Cerebral damage during open-heart surgery. Clinical, psychometric, biochemical and CT data. 349 46

Tricuspid valve prolapse is an infrequent echocardiographic finding that is most commonly associated with mitral valve prolapse. When compared with patients exhibiting isolated prolapse of the mitral valve, patients with tricuspid valve prolapse are somewhat older individuals with a slightly higher frequency of neurologic symptoms, fatigue, weakness, supraventricular arrhythmias (especially atrial fibrillation) and skeletal deformities. Tricuspid valve prolapse may serve as a marker of more-diffuse connective tissue abnormalities, and its identification also should prompt an echocardiographic search for evidence of prolapse and regurgitation of the other heart valves.
Cardiovasc Clin 1987
PMID:Tricuspid valve prolapse. 353 7

A number of centers have recorded a significant incidence of primary tissue failure with the standard Ionescu-Shiley pericardial valve. In most cases severe regurgitation was caused by leaflet tears adjacent to the edge of the cloth-covered stent. Our early clinical experience (up to 4 years' follow-up) with two new pericardial valves (Ionescu-Shiley low-profile and Hancock pericardial valves) has shown that primary tissue failure also occurs in these new valves. In vitro accelerated fatigue studies on seven of these valves (size 29 mm) showed that in vitro premature leaflet failure was caused by abrasion of the leaflet on the cloth-covering at the edge of the stent. Clinically, endothelialization and host tissue ingrowth on the cloth and the leaflets at the edge of the frame greatly reduced the amount of abrasion and the incidence of tissue failure. In seven of the eight explanted valves studied, leaflet tears occurred at the top of the stent posts where there was less endothelialization and tissue ingrowth, close to the points where sutures pass through the leaflets. It is likely that both abrasion and stress concentration around these sutures contributed to the tissue failures in the clinical valves.
J Thorac Cardiovasc Surg 1987 Sep
PMID:Primary tissue failure in pericardial heart valves. 362 99

The hypothesis tested in this study was whether a skeletal muscle could be transformed to be fatigue resistant, to be used to power an implantable extra-aortic balloon assist device, and therefore to provide dynamically significant cardiac assistance. Eight dogs underwent implantation of an Itrel pacemaker to stimulate the thoracodorsal nerve over 8 to 18 weeks and transform the latissimus dorsi muscle. Biopsies of these muscles confirmed near complete (up to 98%) transformation into fatigue-resistance type I muscle fibers, identified by the adenosinetriphosphatase histochemical stains. Biochemical assays showed conversion of myosin isoforms to that of myocardial V3 phenotype, decreased activity of anaerobic glycolytic marker, and increased activity of aerobic enzyme marker, which indicated greater resemblance of such muscle to the myocardial fibers. In four dogs, the optimal stimulation parameters of such muscles in response to a burst stimulator, which synchronizes and summates the muscle contraction, were studied and compared with the contralateral, nontransformed muscle. Fatigue tests confirmed the marked fatigue resistance of the transformed muscle. In four dogs, a 100 ml balloon was placed beneath the transformed latissimus dorsi muscle and connected to the thoracic aorta with a Dacron graft. By means of the optimal burst-stimulating parameters identified above, the latissimus dorsi muscle was stimulated to contract during diastole, compressing the balloon to achieve diastolic augmentation while allowing the balloon to fill during systole. A 39% increase (p less than 0.001) in the "subendocardial viability index" (diastolic pressure-time index/tension-time index) was obtained as calculated from the left ventricular and ascending aortic pressure tracings. We conclude that the skeletal muscle can be transformed to resemble myocardium, which can generate sufficient force to provide hemodynamically significant and clinically relevant counterpulsation.
J Thorac Cardiovasc Surg 1987 Nov
PMID:Implantable extra-aortic balloon assist powered by transformed fatigue-resistant skeletal muscle. 366 97

The latissimus dorsi muscles of six dogs were made fatigue resistant by chronic electrical conditioning. Once the muscles were conditioned, oxygen consumption was measured during periods of exercise. The ratio of the tension developed to oxygen consumed during moderate stimulation (300 msec on) for the control and the electrically conditioned muscles was 16.3 +/- 3.5 and 36.5 +/- 6.7 kg-sec/ml oxygen, respectively. During intense stimulation (800 msec on) the ratio was 12.6 +/- 2.1 and 54.2 +/- 8.9 kg-sec/ml oxygen, respectively. Thus the conditioned muscle was able to develop and maintain tension with a considerably reduced oxygen expenditure. The increased efficiency of the conditioned muscle helps to explain its increased resistance to fatigue and the ability of pumping chambers constructed from electrically preconditioned skeletal muscle to perform sustained cardiac type work.
J Thorac Cardiovasc Surg 1987 Nov
PMID:Oxygen consumption of chronically stimulated skeletal muscle. 366 98

Previous studies show no correlation between resting systolic left ventricular performance assessed as the ejection fraction and exercise tolerance. This study examined the relation between left ventricular diastolic performance and exercise tolerance in 63 patients with left ventricular dysfunction (ejection fraction less than 50%) due to known or suspected coronary artery disease. The 51 men and 12 women, aged 54 +/- 8 years (mean +/- standard deviation), underwent symptom-limited upright exercise testing on a bicycle ergometer. The exercise end-points were angina (n:5), dyspnea (n:16), and fatigue (n:42). The patients were divided into three groups: group 1 (n:28) with normal exercise tolerance (9.5 +/- 2.4 minutes), group 2 (n:18) with mild exercise intolerance (5.8 +/- 0.5 minutes), and group 3 (n:17) had severe exercise intolerance (3.7 +/- 0.9 minutes). The three groups did not differ in age, ejection fraction, end-diastolic volume, exercise end-point, exercise heart rate, and left ventricular peak filling rate at rest. The exercise peak filling rate was, however, significantly higher in group 1 (p = 0.03). Stepwise multivariate discriminant analysis of important variables identified the exercise peak filling rate as the only predictor of exercise tolerance (F = 6.0). Thus, variation in exercise peak filling rate may in part explain the variability of exercise tolerance in patients with left ventricular dysfunction; patients with preserved exercise capacity have higher exercise peak filling rate than those with exercise intolerance.
Cathet Cardiovasc Diagn 1986
PMID:Relation between left ventricular diastolic function and exercise tolerance in patients with left ventricular dysfunction. 379 6

A 10-year-old girl sustained traumatic rupture of the tricuspid valve in an automobile accident. Three years later, progressive fatigue and cardiac enlargement developed. The valve was repaired by pericardial chordal replacements and ring annuloplasty. Nine months postoperatively the patient is in good clinical condition and echocardiography has indicated near-normal function of the tricuspid valve and right ventricle.
J Thorac Cardiovasc Surg 1986 Feb
PMID:Traumatic rupture of the tricuspid valve: repair by chordal replacements and annuloplasty. 394 99


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