Influence of acute sleep loss on the neural correlates of alerting,orientating and executive attention components

The Attention Network Test (ANT) is deemed to assess the alerting, orientating and executive components of human attention. Capitalizing on the opportunity to investigate three facets of attention in a single task, we used functional magnetic resonance imaging (fMRI) to assess the effect of sleep deprivation (SD) on brain responses associated with the three attentional components elicited by the ANT. Twelve healthy volunteers were scanned in two conditions 1 week apart, after a normal night of sleep (rested wakefulness, RW) or after one night of total sleep deprivation. Sleep deprivation was associated with a global increase in reaction times, which did not affect specifically any of the three attention effects. Brain responses associated with the alerting effect did not differ between RW and SD. Higher‐order attention components (orientating and conflict effects) were associated with significantly larger thalamic responses during SD than during RW. These results suggest that SD influences different components of human attention non‐selectively, through mechanisms that might either affect centrencephalic structures maintaining vigilance or ubiquitously perturb neuronal function. Compensatory responses can counter these effects transiently by recruiting thalamic responses, thereby supporting thalamocortical function.     

Randomized, Crossover, Controlled Comparison of Oral Loading Versus Intravenous Infusion of Propafenone in Recent-Onset Atrial Fibrillation

A population of 123 patients witb recent-onset (< 72 hours) atrial fibrillation (AF) without heart failure was randomly treated witb propafenone (PFN) intravenously (IV) (2 mg/kg bolus followed by 0.0078 mg/kg/min infusion) or in a single oral dose (os) (600 mg), or with placebo (PLA) (phase 1). If AF persisted 8 hours later, patients on active drugs received the alternative formulation (crossover), and patients receiving PLA remained on PLA (phase 2). A 24-hour Holter monitoring was performed and conversion to sinus rhythm (SR) at 1,4, and 8 hours of each phase was used as the criterion of efficacy. Conversion to SR occurred within 1 hour in 48% of patients witb IV-PFN, 15 % witb os-PFN, and in 17% with PLA (both P<0.05 vs IV-PFN). Oral PFN was superior to PLA at 4 hours (71 % vs 33%, P = 0.001) and 8 hours (78% vs 48%, P < 0.01), and 1 at 8 hours also superior to IV-PFN (53%, P < 0.03). The mean conversion time within 4 hours was shorter with IV-PFN (25 ± 15') than with os-PFN (167 ± 166, P < 0.001) or with PLA (156 ±107', P < 0.001). The rates of conversion to SR with IV-PFN after os-PFN failure were comparable to PLA at any observation time, whereas nonresponders to IV-PFN who received os-PFN had significantly higher conversion rates than with placebo at both 4 hours (65% vs 19%) and 8 hours (76% vs 24%; both P < 0.045). Neither serious adverse effects nor episodes of regular tachycardia with 1:1 AV conduction were noted. PFN administered intravenously or in a single oral loading dose was safe and efficacious in converting recent-onset AF to SR. The rates of conversion were different with different routes of administration: IV-PFN was superior to os-PFN over a short observation period, while the overall efficacy of os-PFN was superior at 8 hours.     

Is the Left Ventricular Lateral Wall the Best Lead Implantation Site for Cardiac Resynchronization Therapy?

GASPARINI, M., et al .: Is the Left Ventricular Lateral Wall the Best Lead Implantation Site for Cardiac Resynchronization Therapy? Short-term hemodynamic studies consistently report greater effects of cardiac resynchronization therapy (CRT) in patients stimulated from a LV lateral coronary sinus tributary (CST) compared to a septal site. The aim of the study was to compare the long-term efficacy of CRT when performed from different LV stimulation sites. From October 1999 to April 2002, 158 patients (mean age 65 years, mean LVEF 0.29, mean QRS width 174 ms) underwent successful CRT, from the anterior (A) CST in 21 patients, the anterolateral (AL) CST in 37 patients, the lateral (L) CST in 57 patients, the posterolateral (PL) CST in 40 patients, and the middle cardiac vein (MCV) CST in 3 patients. NYHA functional class, 6-minute walk test, and echocardiographic measurements were examined at baseline, and at 3, 6, and 12 months. Comparisons were made among all pacing sites or between lateral and septal sites by grouping AL + L + PL CST as lateral site (134 patients, 85%) and A + MC CST as septal site (24 patients, 15%). In patients stimulated from lateral sites, LVEF increased from 0.30 to 0.39   (P < 0.0001)   , 6-minute walk test from 323 to 458 m   (P < 0.0001)   , and the proportion of NYHA Class III–IV patients decreased from 82% to 10%   (P < 0.0001)   . In patients stimulated from septal sites, LVEF increased from 0.28 to 0.41   (P < 0.0001)   , 6-minute walk test from 314 to 494 m   (P < 0.0001)   , and the proportion of NYHA Class III–IV patients decreased from 75% to 23%   (P < 0.0001)   . A significant improvement in cardiac function and increase in exercise capacity were observed over time regardless of the LV stimulation sites, either considered singly or grouped as lateral versus septal sites. (PACE 2003; 26[Pt. II]:162–168)