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

Isolated dog hearts perfused with blood from a donor dogand driven at two heart rates were used to compare the effects of propranolol with those of its quaternary ammonium derivative on atrial, atrioventricular (AV) nodal, and His-Purkinje conduction. Propranolol slowed only AV-nodal conduction, increasing the minimal conduction time and the effect of prematurity, without affecting fatigue. Practolol did not have this effect. Dimethylpropranolol had similar but not identical effects on the AV node, but also slowed atrial and ventricular conduction. In contrast with the quaternary derivative of lidocaine, dimethylpropranolol's effect on atrial and ventricular conduction was not dependent on the heart rate. The effect of dimethylpropranolol on ventricular conduction was observed at doses lower than those reported by others to be antiarrhythmic.
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PMID:The effect of propranolol and dimethylpropranolol on cardiac conduction. 48 71

His-bundle electrocardiography was used to evaluate the effect of halothane on AV nodal and His-Purkinje system conduction times in the spontaneously beating dog heart. During artrial pacing at basic heart rates of 120 or 200 beats per minute (bpm), an extrastimulus (cycle length longer or shorter than that of the basic rate) was delivered to test the effect of halothane on several parameters of AV nodal conductivity. Included were the functional refractory period, basal conduction time, and fatigue effect (prolongation of basal conduction time as heart rate was increased from 120 to 200 bpm). Increasing MAC level of halothane (1.25 to 2.75 MAC) prolonged both AV node and His-Purkinje conduction times, yet had little effect on the parameters of nodal conductivity tested for. These effects of halothane could be potentially dangerous in the clinical setting for patients with defective AV conduction. In addition, changes in conduction may be in part responsible for arrhythmias seen during halothane anesthesia.
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PMID:Halothane effects on conductivity of the AV node and His-Purkinje system in the dog. 55 37

The effects of lidocaine and methyl lidocaine on cardiac conduction were studied using His bundle recordings from isolated blood perfused dog hearts. The input and output characteristic of the atrioventricular (AV) node can be described as consisting of three components, namely, minimal conduction time, fatigue, and the effect of prematurity (deltaCT). Lidocaine (2.5-10.0 mg/kg) increased minimal conduction time but not fatigue. Methyl lidocaine (1.25-5.0 mg/kg) increased both. A dose of 5 mg/kg or less of either drug caused a nonparallel shift of the deltaCT curve to the right. High doses of lidocaine (10 mg/kg) cause deltaCT to become rate-dependent. Lidocaine slowed atrial conduction only slightly. Atrial block prevented the observation of the effect of methyl lidocaine in doses higher than 5.0 mg/kg. Both drugs showed greater effect on atrial conduction at fast heart rate. Lidocaine did not affect ventricular conduction time at slow heart rates and had only minimal effects at fast heart rates. Methyl lidocaine increased ventricular conduction time at all heart rates. The results of this study indicate that lidocaine and methyl lidocaine have entirely different spectra of activity on cardiac conduction, in that their effect on AV nodal conduction do not differ greatly whereas the quaternary analog has a much stronger depressant effect on atrial and ventricular conduction.
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PMID:Effect of lidocaine and methyl lidocaine on cardiac conduction. 85 Jan 38

The case of a 22-year-old white male without known heart disease who presented with activity related lightheadedness at age 19 and dizziness and fatigue at age 21 is described. Standard electrocardiograms (ECG's) revealed intermittent complete trifascicular block. Rapid progression of symptoms over the succeeding eight months resulted in increasing incapacity. Holter monitoring demonstrated that symptoms were related to development of second and higher degrees of A-V block. Normal A-H interval and markedly prolonged H-Q interval on His bundle electrograms indicated that block was infranodal and localized to bundle branch system. Conduction problems aside, clinical and laboratory evaluation, including echocardiograms and cardiac catheterization, were unremarkable. Progression of bilateral bundle branch disease in a young patient without other demonstrable heart lesions and a negative family background conforms with criteria for Lenegre's disease. To our knowledge, this represents the youngest reported patient with this entity. Possible electrophysiologic basis of block and of exercise induced improvement in A-V conduction also are considered.
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PMID:Lenegre's disease in youth. 91 Jun 82

Two patients with nonpitting edema associated with extreme fatigue were found to have hyperimmunoglobulinemia M and eosinophilia. Additional laboratory abnormalities included an elevated ESR and the presence of rheumatoid factor. One patient had the symptom complex continually, and it was controlled with minimal amounts of prednisone. The other patient had intermittent symptoms, with eosinophilia in the asymptomatic state and decreased eosinophil counts while symptomatic. His symptomatic episodes were diminished in duration by methylprednisolone. We believe these cases, which have been evaluated for eight and four years, respectively, constitute a new syndrome that has substantial morbidity, but that is apparently benign and that can be controlled with corticosteroids.
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PMID:Elevated IgM levels, edema, and fatigue syndrome. 99 19

This report details our total experience with documented chronic His bundle block in 24 patients. Ten patients had second-degree block (eight with 2:1 block and two with type-1 block), and 14 patients had complete heart block. There were 16 women (67 percent) and eight men (33 percent) with ages ranging from 17 to 87 years. Diagnoses were as follows: hypertensive cardiovascular disease, nine patients (38 percent); arteriosclerotic heart disease, six patients (25 percent); aortic valvular disease, three patients (13 percent); primary conduction disease, two patients (8 percent); primary myocardial disease, two patients (8 percent); congenital heart block, one patient (4 percent); and traumatic heart block, one patient (4 percent). Pacing was instituted in 20 patients because of the following; congestive heart failure, seven patients; syncope, seven patients; fatigue, four patients; and recurrent dizziness, two patients. Permanent pacing was indicated within ten days of initial diagnosis in 13 patients, from 20 to 80 days in four patients, and later than 100 days in three patients. An additional two asymptomatic patients were treated with prophylactic pacing.
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PMID:The clinical spectrum of chronic His bundle block. 100 Oct 51

In the first 4 hours after occlusion of the anterior septal coronary artery, 18 dogs developed bundle branch block, heart block, or both. The hearts were then excised, and preparations were dissected to expose the His bundle and the bundle branches, which were superfused with modified Tyrode's solution at 37 degrees C. In the His bundle and the most proximal bundle branches, resting potentials were reduced and diminutive action potentials had slow upstrokes, often with notches or steps. Action potentials were generated by fibers that had resting potentials between--40 and --50 mv. Conduction was impaired; conduction velocities less than 0.01 m/sec were sometimes observed. In more severely affected cells, refractoriness outlasted repolarization. Encroachment on the prolonged refractory period resulted in further diminution of action potentials and continuous rather than intermittent block. More commonly, the response to rapid rate took the form of intermittent block with progressive conduction delay in the series of conducted beats, culminating in a blocked beat (Wenckebach sequence). There was a fatigue factor that accumulated at short cycle lengths and depressed the action potential. Automaticity was not enhanced, but pacemaker function was abnormal. The threshold potential shifted erratically, and pacemaker potentials sometimes were intermittently diminished, resulting in intermittent failure to propagate. During prolonged superfusion, there was a tendency to recover with a drift of the maximum diastolic potentials toward more negative levels. None of these changes were found in ten hearts excised from dogs in which the coronary artery had not been ligated.
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PMID:Disorders of cellular electrophysiology produced by ischemia of the canine His bundle. 111

This report describes the clinical course of a patient with bradycardia and tachycardia-dependent atrioventricular block. Bradycardia dependent A-V block (phase 4 block) was transient and precipitated by spontaneous slowing of the sinus rate, atrial and ventricular extrasystoles; The degree of slowing (critical RP interval) required to induce A-V block increased progressively over a three-day period. Bradycardia-dependent A-V block was terminated mostly by critically times spontaneous or paced ventricular escape beats, but normally conducted atrial impulses also appeared to restore A-V conduction on several occasions. The tachycardia-dependent component was manifested by an unusual fatigue phenomenon in the His-Purkinje system seen only at an atrial pacing rate of 150 per minute. These observations document the presence of both bradycardia and tachycardia-dependent A-V block in the presence of a normal H-V time and also illustrate the dynamic nature of both phase 4 block and the period of "supernormal" intraventricular conduction.
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PMID:Electrocardiographic observations in bradycardia and tachycardia-dependent atrioventricular block. Relationship to supernormal phase of intraventricular conduction. 112 74

The effect of halothane on A-V conduction was evaluated in gods during atrial pacing using the technique of His-bundle electrocardiography. In addition, the effects of lidocaine and diphenylkydantoin (DPH) on A-V conuction were examined during halothane anesthesia. Effects of these drugs on three subintervals of A-V conduction were compared. These included the -H (stimulus atifact of His-bundle deflection-atrioventricular conduction), H-Q (His-budnle deflection onset of QRS complex-His-Purkinje conduction), and H-S intervals(His-bundle delfection to end of QRS COmplex-total intraventricular conduction). Linear regression best described the relationship between duration of interval (P-H, H-V,and H-S) and heart rate during incremental increases in the atrial paced rate. Data from these experiments were fitted to a multiple lenear regression model that predicted the effect of increasing concentrations of halothan, lidocaine, and DPH on slope and intercept coefficients. In creasing concentrations of halothan ( 30 and 45 mg/100 ml arterial). Both lidocaine and DPH further depressed conduction at all levels of halothan anesthesia. The P-H interval was particularly sensitive todrug effefts. This may represent potentiation of the normal slowing of conduction through the AVnode in response to incremental increases in heart rate (fatigue response.) We conclude thatboth lidocaine and DPH fail to reverse the depressant effect of halothane on A-V conduction. This may explain their ineffectiveness in treating certain types of arrhythmias during halothane anesthesia.
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PMID:Diphenylhydantoin and lidocaine modification of A-V conduction in halothane-anesthetized dogs. 114 8

A case of brain metastasis of lung cancer with Eaton-Lambert syndrome (ELS) is reported. A 45-year-old male was admitted to the Department of Surgery in Kurume University Hospital on November 13, 1985, complaining of general fatigue. On admission, neurological examination revealed diplopia and fatigue of the extremities. The electromyogram (EMG) showed the waning phenomenon in low frequency repetitive stimulation (2Hz) and the waxing phenomenon in high frequency repetitive stimulation (10Hz, 20Hz). His clinical symptoms, radiological findings and EMG findings demonstrated lung cancer with ELS. Left pulmonary lobectomy with lymphnode dissection of the anterior mediastinum and pulmonary hilus was performed on December 4. Intraoperatively, the tumor was strongly adherent to a medium lymphnode. The patient experienced complete relief symptoms due to ELS. Histological examination disclosed a small cell carcinoma without lymphnode metastasis. He was discharged without any neurological deficits following chemotherapy on February 27, 1986. He was readmitted to the Department of Neurosurgery on August 29, 1986, because of the development of nausea and vomiting. Neurological examination demonstrated no abnormalities except for choked disc in the bilateral ocular fundi. The computed tomography scan revealed a metastatic brain tumor with a mural nodule and cyst. The tumor was totally removed on September 2. Histological examination revealed a typical appearance of small cell carcinoma. He followed a satisfactory postoperative course. He was discharged following radiation therapy on November 2, 1986, and was followed as an outpatient. He has no problem in daily life since then. Though the patient had an expanding metastatic brain tumor from lung cancer after the first operation, he experienced no symptoms due to ELS.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Brain metastasis of lung cancer with Eaton-Lambert syndrome--case report]. 132 90


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