Multiparametric Analysis of Heart Rate Variability Used for Risk Stratification Among Survivors of Acute Myocardial Infarction

A multiparametric heart rate variability analysis was performed to prove if combined heart rate variability (HRV) measures of different domains improve the result of risk stratification in patients after myocardial infarction. In this study, standard time domain, frequency domain and non-linear dynamics measures of HRV assessment were applied to 572 survivors of acute myocardial infarction. Three parameter sets each consisting of 4 parameters were applied and compared with the standard measurement of global heart rate variability HRVi. Discriminant analysis technique and t-test were performed to separate the high risk groups from the survivors. The predictive value of this approach was evaluated with receiver operator (ROC) and positive predictive accuracy (PPA) curves. Results - The discriminant analysis shows a separation of patients suffered by all cause mortality in 80% (best single parameter 74%) and sudden arrhythmic death in 86% (73%). All parameters of set I show a high significant difference (p<0.001) between survivors and non-survivors based on two-tailed t-test. The specificity level of the multivariate parameter sets is at the 70% sensitivity level (ROC) about 85–90%, whereas HRVi shows maximum levels of 70%. The PPA in the all cause mortality group is at the 70% sensitivity level twice as high as the univarihate HRV measure and increases to more than fourfold as high within the VT/VF group. In conclusion, in this population, the multiparametric approach with the combination of four parameters from all domains especially from NLD seems to be a better predictor of high arrhythmia risk than the standard measurement of global heart rate variability.     

Prevalence of Hyperglycaemia and Undiagnosed Diabetes Mellitus in Patients with Acute Myocardial Infarction

ABSTRACT The prevalence of hyperglycaemia and undiagnosed diabetes mellitus was assessed in 214 consecutive patients admitted to the coronary care units with acute myocardial infarction (AMI). On admission, 16 patients (7.5%) had known diabetes, and 19 patients, not previously known to be diabetic, had blood glucose concentrations of ≥9 mmol/1. Fifteen patients survived for 2 months at which time a 75 g oral glucose tolerance test showed diabetes in 9 (60%) and impaired glucose tolerance in 4 (27%). Ten of these 13 patients (77%) with abnormal glucose tolerance had elevated glycosylated haemoglobin (HbA_1c) on admission, indicating pre-existing glucose intolerance or diabetes. The prevalence of undiagnosed diabetes was 4.5% (9/198). However, we may have overlooked undiagnosed diabetes in a small number of patients on admission, since only a random blood glucose <8 mmol/1 rules out diabetes, WHO criteria. Elevated blood glucose in patients with AMI is more likely to reflect a stationary pre-existing abnormal glucose tolerance than a temporary stress-induced phenomenon.     

Neurophysiological correlates of mental arithmetic

Thirteen subjects were extensively trained on nine multiplication problems varying in difficulty. Practice was associated with a reaction time speed up and an attenuation of the problem size effect. The introduction of previously unpracticed problems led to a performance rebound to pretraining levels, indicating practice specificity. The event-related potentials were characterized by a late positive complex, followed by a positive slow wave. Offset latency of positive slow wave and preresponse amplitude at parietal electrodes showed practice specificity effects that systematically changed with practice and problem size, indicating an association with the load imposed on working memory. The peak of the late positive complex probably reflects task learning or adaptation effects because it was attenuated by practice predominantly at frontal electrodes, showed no practice specificity, and was not affected by problem size.     

Enhanced sympathetic nervous activity after intravenous propranolol in ischaemic heart disease: plasma noradrenaline splanchnic blood flow and mixed venous oxygen saturation at rest and during exercise

To study the mechanisms by which acute beta-adrenergic blockade may change the activity of the sympathetic nervous system we have measured haemodynamic responses including splanchnic blood flow in twenty-three patients with ischaemic heart disease at rest and during supine exercise before and after i.v. injection of 0.039 mmol (10 mg) dl-propranolol. After propranolol both at rest and on exercise blood pressure, cardiac output and heart rate decreased, while splanchnic vascular resistance increased; mixed venous oxygen saturation decreased whilst arterial oxygen saturation and oxygen uptake were unchanged. Plasma noradrenaline increased after propranolol, values correlating with mixed venous oxygen saturation and splanchnic vascular resistance, both at rest and during exercise before and after propranolol, only at rest was there any correlation with arterial blood pressure. The increase in sympathetic nervous activity after propranolol may be due to a reduction in cardiac output and thereby alteration of the metabolic state (oxygen or related factors) in tissues. Afferent neural signals from the tissues may play a significant role in the regulation of sympathetic nervous activity.     

Cortical correlates of semantic classical conditioning

Event-related potentials to visually displayed pseudowords were registered from 13 individuals. In a differential conditioning paradigm, half of the pseudowords had previously been paired with a painful electric shock (shock words) and the other half had been presented without shock (nonshock words). Participants were asked to decide if the words had been presented during the conditioning phase or not. Larger N100 amplitudes and a more negativegoing slow wave 400–800 ms after word presentation were found for shock as compared with nonshock words. This effect was stronger over the left than over the right hemisphere. This left-lateralized negativity might reflect the activation of a cell assembly representing the memory of the learned word-shock contingency. Furthermore, the increased N100 amplitude elicited by shock as compared with nonshock words may be interpreted as an increased attentive facilitation for aversive pain-related information as a consequence of conditioning.     

PSEUDOMONAS AERUGINOSA INFECTION IN CYSTIC FIBROSIS: Occurrence of Precipitating Antibodies against Pseudomonas Aeruginosa in Relation to the Concentration of Sixteen Serum Proteins and the Clinical and Radiographical Status of thi Lungs

ABSTRACT, Heiby, N., Jacobsen, L., Jergensen, B. A., Lykkegaard, E. and Weeke, B. (Statens Seruminstitut, Department of Clinical Microbiology at Blegdamshospitalet, the Paediatric Clinic TG with the Paediatric Clinic of Dronning Louises Børnehospital, the Radiologic Department TX, Rigshospitalet, and the Protein Laboratory, Untversity of Copenhagen, Copenhagen, Denmark). Pseudomonas aeruginosa infection in cystic fibrosis. Acta Paediatr Scand, 63: 843, 1974.—The significance of Pseudomonas aeruginosa infection in the respiratory tract of 9 cystic fibrosis patients have been studied by means of immunoelectrophoretical analysis of patients' sera for the number of precipitins against Pseudomonas aeruginosa and the concentrations of 16 serum proteins. In addition, the clinical and radiographical status of the lungs have been evaluated using 2 scoring systems. Precipitins against Pseudomonas aeruginosa were demonstrated in all sera, the maximum number in one serum was 22. The concentrations of 12 of the serum proteins were significantly changed compared with matched control persons. Notably IgG and IgA were elevated and the "acute phase proteins" were changed, the latter suggesting active tissue damage. The concentrations of 3 of the acute phase proteins, notably haptoglobin were correlated to the number of precipitins suggesting that the respiratory tract infection in patients with many precipitins is accompanied by more tissue damage than the infection in patients with few precipitins. The results indicate no protective value of the many precipitins on the tissue of the respiratory tract.