EEG sigma and slow‐wave activity during NREM sleep correlate with overnight declarative and procedural memory consolidation

Previous studies suggest that sleep‐specific brain activity patterns such as sleep spindles and electroencephalographic slow‐wave activity contribute to the consolidation of novel memories. The generation of both sleep spindles and slow‐wave activity relies on synchronized oscillations in a thalamo‐cortical network that might be implicated in synaptic strengthening (spindles) and downscaling (slow‐wave activity) during sleep. This study further examined the association between electroencephalographic power during non‐rapid eye movement sleep in the spindle (sigma, 12–16 Hz) and slow‐wave frequency range (0.1–3.5 Hz) and overnight memory consolidation in 20 healthy subjects (10 men, 27.1 ± 4.6 years). We found that both electroencephalographic sigma power and slow‐wave activity were positively correlated with the pre–post‐sleep consolidation of declarative (word list) and procedural (mirror‐tracing) memories. These results, although only correlative in nature, are consistent with the view that processes of synaptic strengthening (sleep spindles) and synaptic downscaling (slow‐wave activity) might act in concert to promote synaptic plasticity and the consolidation of both declarative and procedural memories during sleep.     

Influence of Renal Sympathetic Denervation on Quality of Life

Background

Therapy‐resistant arterial hypertension causing psychosocial stress and is associated with cardiovascular morbidity and mortality. The aim of the study was to evaluate the effect on quality of life (QoL) in patients with resistant hypertension undergoing renal sympathetic denervation (RSD).

Methods and Results

We analyzed responses to the SF‐36 Quality of Life Questionnaire provided by patients with resistant arterial hypertension after RSD. Thirty consecutive patients from 2 centers were included in this study, from October 2011 until February 2012. The phone interview was performed after the 3‐month follow‐up. A significant reduction (26 ± 13.5 mmHg) in systolic blood pressure (BP) was detected at the 3‐month follow‐up (142.0 ± 15.1 mmHg vs 168.0 ± 13.7 mmHg; P < 0.001). Seventy‐five percent of the patients indicated that their health situation was a lot better (better, 21%; equal to, 4%) 3 months after RSD compared to the time before the therapeutic procedure. Furthermore, the majority of patients felt full of pep (always, 29%; mostly, 58%; quite often, 8%; sometimes, 4%), and full of energy (always, 25%; mostly, 54%; quite often, 16.7%; sometimes, 4.2%) after the procedure. Recipients of RSD indicated that they felt more light and healthy, and nearly all recipients (93%) described a loss of anxiety and indisposition.

Conclusions

This investigation revealed that sufficient BP reduction by RSD and time following therapeutic success lead to significant improvements in patient QoL. (J Interven Cardiol 2013;26:536‐541)

     

Effects of Exposure to GSM Mobile Phone Cortisol,Alpha-Amylase,and Base Station Signals on Salivary Immunoglobulin A

Objective The present study aimed to test whether exposure to radiofrequency electromagnetic fields （RF-EMF） emitted by mobile phone base stations may have effects on salivary alpha-amylase, immunoglobulin A （IgA）, and cortisol levels. Methods Fifty seven participants were randomly allocated to one of three different experimental scenarios （22 participants to scenario 1, 26 to scenario 2, and 9 to scenario 3）. Each participant went through five 50-minute exposure sessions. The main RF-EMF source was a GSM-900-MHz antenna located at the outer wall of the building. In scenarios 1 and 2, the first, third, and fifth sessions were ＂low＂ （median power flux density 5.2 μW/m^2） exposure. The second session was ＂high＂ （2126.8 μW/m^2）, and the fourth session was ＂medium＂ （153.6 μW/m^2） in scenario 1, and vice versa in scenario 2. Scenario 3 had four ＂low＂ exposure conditions, followed by a ＂high＂ exposure condition. Biomedical parameters were collected by saliva samples three times a session. Exposure levels were created by shielding curtains. Results In scenario 3 from session 4 to session 5 （from ＂low＂ to ＂high＂ exposure）, an increase of cortisol was detected, while in scenarios 1 and 2, a higher concentration of alpha-amylase related to the baseline was identified as compared to that in scenario 3. IgA concentration was not significantly related to the exposure. Conclusions RF-EMF in considerably lower field densities than ICNIRP-gnidelines may influence certain psychobiological stress markers.     

In-hospital experience with multiprogrammable implantable antitachycardia/antifibrillation devices

Multiprogrammable, automatic internal defibrillators with (n= 45) and without (n = 15) antitachycardia pacing features wereimplanted in 60 consecutive patients with refractory, malignantventricular tachycardia (VT) (n = 42) or fibrillation (VF) (n= 18). Left ventricular (LV) ejectionfraction wasreduced to39% ± 12% as a result of structural heart disease in56 patients. The complexity of the systems caused no additionalrisks to the surgical procedure or postoperative management.VT/VF detection parameters were individually adjusted to thearrhythmia type (detection cycle length 323 ± 40 ms inpatients with VF vs 405 ± 40 ms for VT patients, P<0.05)and incidence (longer detection periods if frequent nonsustainedVT was also present). Shock energy was reduced in patients withVT as compared to VF(11J vs 24J, P<0.05). Antitachycardiapacing was activated in 19/28 (68%) patients with well toleratedVT. Signal, telemetry, as detected by the device, combined withprogrammability allowed the device to be checked for correctdecisions (these were inappropriate in four patients in threeof whom corrections were non-invasive) prior to discharge. Inconclusion, in the automatic tachyarrhythmia control deviceswe studied, programmability and flexibility appeared to be clinicallysafe and useful. Prolonged observation periods are required,however, to evaluate the true clinical safety and persistentefficacy of device programmability and flexibility.     

Incidence of T Wave Alternation After Acute Myocardial Infarction and Correlation with Other Prognostic Parameters: Results of a Prospective Study

Tachycardia induced alternation of the T wave (TWA) has been associated with arrhythmia morbidity in mixed patient populations. However, less is known concerning the general incidence of TWA and its usefulness in risk stratification early after acute myocardial infarction (MI). TWA was prospectively and systematically assessed in 140 consecutive patients 15 +/- 6 days after acute MI and prior to discharge. Results of TWA measurements were compared to other noninvasive risk markers, LV function, and coronary angiography. Sustained TWA was present at rest or inducible during exercise in 27% of patients. The patient-specific heart rate for the onset of TWA was 98 +/- 9 beats/min. After multivariate analysis, TWA correlated with age (P = 0.02) and LV function (P = 0.002) and occurred more often in patients after nonanterior MI (P = 0.03). Acute results of Holter monitoring, late potentials by signal-averaged ECG, and heart rate variability were unrelated to the TWA status. During follow-up (451 +/- 210 days) two major arrhythmic events occurred. The incidence of TWA early after MI is about 25%. TWA is related to age and LV function but not to other common arrhythmia markers. Although TWA does not appear to be related to excessive cardiac morbidity, evaluation of the prognostic significance of TWA requires further study.     

Enhanced psychophysiological signs of attention after angiotensin-converting enzyme inhibition by captopril

Complementary to its essential role in the central nervous control of cardiovascular activity, the neuropeptide angiotensin 11 may regulate attentional processes. The present study evaluated central nervous, cardiovascular, and sympathetic indicators of attention after inhibition of angiotensin II synthesis by captopril (50 mg vs. placebo) in 14 men. Event-related potentials (ERPs) and stimulus-related electroencephalographic (EEG) activity were recorded while the subject performed an auditory oddball task. Captopril increased both the N1-P2 component of the ERP (p < .05) and – following the first tone of the task – the EEG desynchronization in the lower alpha frequency band (p < .05). Although blood pressure remained unchanged, heart rate was lowered (p < .05) and plasma norepinephrine concentrations increased (p < .01) after captpril. The effects suggest that inhibition of angiotensin II synthesis enhances an attentional state typically present during sensory intake.     

An Increase in Sinus Rate Following Radiofrequency Energy Application in the Posteroseptal Space

An increase in sinus rate has been previously described in patients with AV node reentry (AVNRT) following successful A V node modification. This increase could either be a specific sign of elimination of slow pathway conduction or it could be a consequence of energy application in the posteroseptal area. Thus, we compared the changes in sinus cycle length following successful slow pathway ablation (defined as complete elimination of dual AV node physiology) in patients having AVNRT with those in patients undergoing successful ablation of a posteroseptal atriovetriricular accessory connection. Twenty five patients (16 women and 9 men, mean age 41 ± 4 years) with typical AVNRT (cycle length 378 ± 12 ms and 29 patients (16 women and 13 men, age 34 ± 5 years) with an accessory connection (17 manifest and 12 concealed) were studied. The electrophysiology study was performed during sedation with Fentanyl and Midazolam. The mean number of energy applications was 3 ± 1 for successful slow pathway ablation and 4 ± 1 for successful ablation of the accessory connection (p:NS). Following the successful energy application, the sinus cycle length decreased significantly 776 ms at baseline to 691 ms in patients with AVNRT. Following successful ablation of the posteroseptal AC, sinus cycle length decreased from 755 ms at baseline to 664 ms (p < 0.05 in both groups [difference between groups not significant]). The decrease in sinus cycle length did not correlate with the number ofRF energy applications required for successful ablation or the total energy delivered. In conclusion, ablation of the AV node slow pathway and a posteroseptal accessory connection results in similar increases in the sinus rate. Thus, the increase in sinus rate is probably due to energy application in the posteroseptal space, possibly due to concomitant destruction of vagal inputs, and it is not specific for elimination of slow pathway conduction.     

Benign Prognosis of Early Sinus Node Dysfunction After Orthotopic Cardiac Transplantation

Previous reports raised concern about the prognosis of patients with sinus node (SN) dysfunction after cardiac transplantation and led to a low threshold for permanent pacemaker (PM) placement at most institutions. The present study addresses the survival in patients with normal and impaired post operative SN function and the effect of permanent pacing with respect to overall and cardiac mortality. There were 120 patients with normal (corrected SN recovery time < 520 ms, group I) and 47 patients with impaired SN function (corrected SN recovery time < 520 ms and/or sinus arrest ± escape rhythms). Pacing support was deemed unnecessary in 23 of 47 patients with SN dysfunction (group II; asymptomatic SN bradycardia and corrected SN recovery time 3,812 ± 5,800 ms) while a total of 24 patients had PM placement a mean of 29 ± 44 days after transplantation (symptomatic bradycardia or absence of sinus rhythm at discharge, group III). Patients were followed for a mean of 46.7 months. Thirty-five deaths occurred during the study period. Sixteen deaths were cardiac but none were causally related to the SN dysfunction (graft failure due to rejection or atheropathy n =14; myocardial infarction n = 2). Four of these cardiac deaths were sudden and all occurred in the presence of widespread structural abnormalities (rejection/vasculopathy/myocardial infarction). SN dysfunction was not related to overall (P = 0.25) or cardiac mortality (P = 0.33). Regarding either endpoint, patients who had permanent PM placement did no belter than their unpaced counterparts in group II (P = 0.53 and P = 0.33, overall and cardine mortality, respectively). Likewise, survival did not differ between groups 1 and III for either endpoint (P = 0.77, P = 0.65, respectively). These data suggest that patients with mild SN abnormality, who are in sinus rhythm at the time of discharge, can be followed by observation without specific therapy.