Ischaemic stroke, snoring and obstructive sleep apnoea

SUMMARY  Ischaemic stroke occurs most often during the morning hours before noon. In recent studies the peak time of onset has been between 10.00 and 12.00 hours. Snoring every night or almost every night (habitual snoring) is in relation with ischaemic stroke. Snoring occasionally, on the contrary, is not significantly related with stroke. Habitual snoring is the most typical sign of obstructive sleep apnoea syndrome and it is strongly associated with being overweight. Other possible pathophysiological factors that are in relation with habitual snoring, obstructive sleep apnoea and stroke include arterial hypertension, changes in fibrinolytic activity, adult onset diabetes and smoking. It remains to be seen whether nightly occurring partial upper airway obstruction (habitual snoring) with intrathoracic pressure changes is an independent risk factor of ischaemic stroke. There is recent evidence that everything cannot be explained by other known risk factors.     

Magnetocardiographic Intra-QRS Fragmentation Analysis in the Identification of Patients with Sustained Ventricular Tachycardia after Myocardial Infarction

KORHONEN, P., et al. : Magnetocardiographic Intra-QRS Fragmentation Analysis in the Identification of Patients with Sustained Ventricular Tachycardia after Myocardial Infarction. The aim of this study was to investigate if magnetocardiographic (MCG) analysis of cardiac micropotentials within the QRS complex can identity patients prone to ventricular arrhythmias, and to compare it to MCG time-domain, late-field analysis. The study population consisted of 136 patients with remote MI, 53 with and 83 without a history of VT. After averaging and high pass filtering of multichannel MCG signals, time-domain parameters describing the end-QRS activity and fragmentation index M and score S describing the whole QRS complex were computed. Fragmentation and time-domain parameters differed between the VT and control groups: fragmentation index M was  12 ± 3  versus  9 ± 2  (  P < 0.001  ), fragmentation score S was  83 ± 42  versus  56 ± 21  (  P < 0.001  ), and filtered QRS duration was  144 ± 32  versus  114 ± 19 ms  (  P < 0.001  ) in VT and control groups, respectively. A combination of fragmentation parameters yielded 87% sensitivity and 61% specificity in VT identification. Corresponding figures for a time-domain parameter combination were 81% and 72%. Sensitivity of time-domain analysis was 88% and specificity was 75% in a subgroup with anterior MI. In multivariate analysis, fragmentation and time-domain analyses discriminated VT patients from controls independently of the extent of coronary artery disease or left ventricular dysfunction. MCG in postinfarction patients reveals pathology associated with propensity to ventricular arrhythmias inside and not only at the end of the QRS complex. MCG seems most accurate in the anterior infarct location.     

Factors associated with calcific aortic valve degeneration in the elderly

This study aimed at identifying factors influencing aortic valvecalcification in old age. Echocardiographic and Doppler characteristicsof the aortic valve were compared with possible clinical andbiochemical predictors in 501 people aged 75–86 yearsand in 76 aged 55–71. Slight calcification was seen in222 people (40%) and severe calcification in 72 (13%); 21 peoplehad moderate or severe aortic stenosis. Age (P=0.000) and serumparathyroid hormone (P=0.015) were higher and body mass indexlower (P=0.002) in the presence of aortic valve calcification.In multivariate analysis, age (P=0.000), hypertension (P=0.005)and body mass index (P=0.005) were independent predictors ofaortic valve calcification, and age (P=0.022) and serum ionizedcalcium (P=0.037) of valve stenosis. The odds ratio (95% confidenceinterval) for valve calcification was 1.89 (1.42–2.50)for a 10-year increase in age, 1.74 (1.19–2.55) in thepresence of hypertension, and 1.39 (1.10–1.76) for a 5kg. m^–2 decrease in body mass index. Sex, smoking, diabetes,serum lipids and insulin were unrelated to valvular calcification.These data suggest that leanness and a history of hypertensionincrease the likelihood of senile aortic valve calcification.Calcium metabolism may also be of significance. The mechanismsof these associations deserve further study.     

Magnetocardiographic QT Interval Dispersion in Postmyocardial Infarction Patients with Sustained Ventricular Tachycardia: Validation of Automated QT Measurements

T dispersion is a measure of heterogeneity in ventricular repolarization. Increased ECG QT dispersion is associated with life-threatening ventricular arrhythmias. We studied if magnetocardiographic (MCG) measures of QT dispersion can separate postmyocardial infarction patients with and without susceptibility to sustained VT. Manual dispersion measurements were compared to a newly adapted automatic QT interval analysis method. Ten patients with a history of sustained VT (VT group) and eight patients without ventricular arrhythmias (Controls) were studied after a remote myocardial infarction. Single-channel MCGs were recorded from 42 locations over the frontal chest area and the signals were averaged. QT dispersion was defined as maximum — minimum or standard deviation of measured QT intervals. VT group showed significantly more QT and JT dispersion than Controls. QT_apex dispersions were 127 ± 26 versus 83 ± 21 ms (P = 0.004) and QT_end dispersions 130 ± 37 versus 82 ± 37 ms (P = 0.013), respectively. Automatic method gave comparable values. Their relative differences were 9% for QT_apex and 27% for QT_end dispersion on average. In conclusion, increased MCG QT interval dispersion seems to be associated with a susceptibility to VT in postmyocardial infarction patients. MCG mapping with automated QT interval analysis may provide a user independent method to detect nonhomogeneity in ventricular repolarization.     

NUMBER AND MORPHOLOGY OF MECHANORECEPTORS IN THE MYOTENDINOUS JUNCTION OF PARALYSED HUMAN MUSCLE

The mechanoreceptor system of the myotendinous junction (MTJ) of human palmaris longus muscle obtained at autopsy was studied histologically from six patients with flaccid paralysis (complete acute tetraplegia 4–6 weeks before the autopsy, due to a spinal cord injury), eight patients with spastic paralysis (chronic hemiplegia due to cerebral stroke) and ten neurologically normal controls. Four types of nerve endings, Ruffini and Pacini corpuscles, Golgi tendon organs, and free nerve endings, could be identified in the MTJs of the controls. In the MTJs of the patients with flaccid and spastic paralysis, the free nerve endings were not present and the mechanoreceptors that were found were few in number, degenerated, fibrotic, and atrophic. These mechanoreceptors had lost their connection with the muscle fibres and tendon bundles and were frequently located within pathological accumulations of fatty tissue in the myotendinous region. The number and distribution of mechanoreceptors in the MTJ were almost identical in patients with flaccid and spastic paralysis.     

A PROSPECTIVE CLINICAL STUDY OF ROTAVIRUS DIARRHOEA IN YOUNG CHILDREN

Abstract. Mäki, M. (Department of Paediatrics, Tampere Central Hospital, Tampere, Finland). A prospective clinical study of rotavirus diarrhoea in young children. Acta Paediatr Scand, 70:107, 1981.–The clinical and laboratory features of 96 children aged 6 to 36 months with acute rotavirus diarrhoea were compared to findings on 63 children of the same age with acute non-rotavirus diarrhoea. Of the rotavirus-associated cases 80% occurred between January and June. In general, the diarrhoea was more severe in these patients than in the others, but no difference was seen in duration of symptoms. Clinical features characteristic of rotavirus-associated cases included: dehydration and acidosis upon admission, vomiting, fever, neutropenia and sugar in the stools (Clinitesf® 0.5 %). In contrast, no difference was seen in the occurrence of respiratory symptoms (53 % in the rotavirus, 62% in the non-rotavirus group), or in the presence of mucus strands, occult blood or leucocytes in stools. A combination of the above criteria may be helpful in the presumptive diagnosis of rotavirus diarrhoea.     

Hazard Screening and Proposals for Prevention by Occupational Health Service: An Experiment with Job Load and Hazard Analysis at a Finnish Construction Company

In this study a systematic method for workplace investigationwas developed and then tested as part of the regular occupationalhealth care procedures in the building trade. Workplace investigationis a concept which entails the analysis of hazards inherentin the work as well as assessment of their effects on workers'well-being. The aim of this paper is to evaluate the effectivenessof the workplace investigation method. The newly developed method,called Job Load and Hazard Analysis, has the following characteristics:a job analytic approach; the application of group problem-solving;and cooperation between occupational health professionals, occupationalsafety personnel, and line management. The method comprisesthe identification of health hazards, their assessment, andconclusions and proposals as to their prevention and follow-up.The method was tested as part of one constructor's actual occupationalhealth care programme, over a 2.5-year period. The method workedwell as a central component of preventive occupational healthcare. It yielded concrete data that could be applied to makethe occupational health care programme better suited to preventingthe hazards inherent in the building trade. The contents ofthe occupational health care programme were clearly enhanced,the number of preventive measures increased, and the organizationalclimate improved; the workers praised the increased emphasison safety. More research is needed, eg in other production settingsand to determine the most effective utilization of the datagathered by the method. Requests for reprints should be addressed to: Professor Markku Mattila, DTECH, Occupational Safety Engineering, Tampere University of Technology, P.O. Box 527, SF-33101, Tampere, Finland     

Predictors of left ventricular mass in old age: an echocardiographic, clinical and biochemical investigation of a random population sample

The potential predictors of left ventricular mass in old agewere studied in a random sample of people born in 1904, 1909,1914 (n=501; and 1920-35 (n=76). Data on the left ventriclewith mass calculation, quantitative data on value disordersand biochemical data were collected. Left ventricular mass (correctedfor height) was positively related to male gender, age, bodymass index and systolic blood pressure. It was also significantlyhigher in the presence of aortic valve calcification, a lowvelocity ratio (indicating aortic value obstruction), and aorticor mitral re gurgitation. In men, left ventricular mass washigher in the presence of coronary artery disease and inverselyrelated to serum high density lipoprotein cholesterol. In multivariateanalysis, independent predictors of left ventricular mass withoutsex interaction were age (standardized coefficient ß=0.23,P=0.000). male gender (ß=0.38, P=0.000), body massindex (ß=0.22, P=0.000), systolic blood pressure (ß=0.21,P=0.000), velocity ratio (ß=-0.11, P=0.010), detectableaortic regurgitation (ß=0.11, P=0.014) and moderate-to-severemitral regurgitation (ß=0.21, P=0.014) and moderate-to-severemitral regurgitation (ß=0.21, P=0.000). Thus, theincrease in left ventricular mass with age can largely be relatedto discrete predictors. The impact of valve disorders is substantial.     

Rocuronium in infants, children and adults during balanced anaesthesia

We studied 20 infants, 20 children and 20 adults during balanced anaesthesia to compare the neuromuscular blocking effects of rocuronium in these age groups. Neuromuscular function was recorded by adductor pollicis emg and a cumulative log-probit dose-response curve of rocuronium was established. Thereafter, full spontaneous recovery of the neuromuscular function was recorded. Onset time of the first dose of rocuronium was shorter in children than in infants or adults. The potency of rocuronium was greatest in infants and least in children; the ED₅₀ doses (mean ± SD) being 149 ± 36 μg˙kg^?1 in infants, 205 ± 52 μg˙kg^?1 in children and 169 ± 47 μg˙kg^?1 in adults (P<0.05 between infants and children) and the ED₉₅ doses being 251 ± 73 μg˙kg^?1, 409 ± 71 μg˙kg^?1 and 350 ± 77 μg˙kg^?1, respectively (P<0.05 between all groups). The emg recovery following an average 94.5 ± 4.8% neuromuscular blockade established by rocuronium was roughly similar in all study groups. Thus, one ED₉₅ dose of rocuronium, unlike vecuronium, acts as an intermediate-acting agent in all age groups.