Sleep deprivation suppresses the increase of rapid eye movement density across sleep cycles

We investigated the association between rapid eye movement (REM) density (REMd) and electroencephalogram (EEG) activity during non‐rapid eye movement (NREM) and REM sleep, within the re‐assessment, in a large sample of normal subjects, of the reduction of oculomotor activity in REM sleep after total sleep deprivation (SD). Coherently with the hypothesis of a role of homeostatic sleep pressure in influencing REMd, a negative correlation between changes in REMd and slow‐wave activity (SWA) was expected. A further aim of the study was to evaluate if the decreased REMd after SD affects ultradian changes across sleep periods. Fifty normal subjects (29 male and 21 female; mean age = 24.3 ± 2.2 years) were studied for four consecutive days and nights. Sleep recordings were scheduled in the first (adaptation), second (baseline) and fourth night (recovery). After awakening from baseline sleep, a protocol of 40 h SD started at 10:00 hours. Polysomnographic measures, REMd and quantitative EEG activity during NREM and REM sleep of baseline and recovery nights were compared. We found a clear reduction of REMd in the recovery after SD, due to the lack of REMd changes across cycles. Oculomotor changes positively correlated with a decreased power in a specific range of fast sigma activity (14.75–15.25 Hz) in NREM, but not with SWA. REMd changes were also related to EEG power in the 12.75–13.00 Hz range in REM sleep. The present results confirm the oculomotor depression after SD, clarifying that it is explained by the lack of changes in REMd across sleep cycles. The depression of REMd can not simply be related to homeostatic mechanisms, as REMd changes were associated with EEG power changes in a specific range of spindle frequency activity, but not with SWA.     

Echocardiographic and Electrocardiographic Predictors for Atrial Fibrillation Recurrence Following Cardioversion

Introduction: Identification of suitable candidates for cardioversion currently is not based on individual electrical and mechanical atrial remodeling. Therefore, this study analyzed the meaning of atrial fibrillatory rate obtained from the surface ECG (as a measure of electrical remodeling) and left atrial size (as measure of mechanical remodeling) for prediction of early atrial fibrillation (AF) recurrence following cardioversion.
Methods and Results: Forty-four consecutive patients (26 men and 18 women, mean age 62 ± 11 years, no antiarrhythmic medication at baseline) with persistent AF were studied. Fibrillatory rate was obtained from high-gain, high-resolution surface ECG using digital signal processing (filtering, QRST subtraction, Fourier analysis) before electrical cardioversion. Univariate and multivariate regression analysis revealed larger systolic left atrial area (Beta = 0.176, P = 0.031) obtained by precardioversion echocardiogram from the apical four-chamber view and higher atrial fibrillatory rate (Beta = 0.029, P = 0.021) to be independent predictors for AF recurrence (n = 13). Stratification based on the regression equation (electromechanical index [EMI]= 0.176 systolic left atrial area + 0.029 fibrillatory rate − 17.674) allowed identification of groups at low, intermediate, or high risk. No patient with an EMI < −1.85 had early AF recurrence, as opposed to 78% with an EMI > −0.25. Intermediate results (40% recurrence rate) were obtained when the calculated EMI ranged between −1.85 and −0.25 (P < 0.001).
Conclusion: Fibrillatory rate obtained from the surface ECG and systolic left atrial area obtained by echocardiography may predict early AF recurrence in patients with persistent AF. These parameters might be useful in identifying candidates with a high likelihood of remaining in sinus rhythm after cardioversion. (J Cardiovasc Electrophysiol, Vol. 14, pp. S162-S165, October 2003, Suppl.)     

Near‐infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients

Background: Cerebral regional oxygen saturation (rSO₂) measured with near‐infrared spectroscopy (NIRS) has a well‐proven clinical utility. A goal‐oriented treatment based on the rSO₂ resulted in a significant reduction in major morbidity and in a shortening of postoperative hospital stay in patients undergoing coronary revascularization. In this study, we have compared the values of superior vena cava saturation (ScvO₂) continuously measured with a Pediasat catheter and the corresponding NIRS rSO₂ values obtained during cardiac operations in pediatric patients. Methods: This was a prospective observational study enrolling fifteen pediatric patients (age: 6 days–7 years) undergoing cardiac operations. ScvO₂ data obtained with the Pediasat during the operation were compared with simultaneously recorded NIRS rSO₂ values. Results: One hundred and seventeen matched sets of data were obtained during the operation. ScvO₂ continuously measured with the Pediasat was significantly correlated with the corresponding NIRS rSO₂ values. However, there was a constant positive bias (ScvO₂ values were higher than NIRS rSO₂ values) of 5.6%, with a precision of 10.4%. Time‐related percentage changes of NIRS rSO₂ were significantly correlated with the corresponding ScvO₂ percentage changes. A decrease in ScvO₂ is predictive for a decrease in rSO₂ with a sensitivity of 73.7% and a specificity of 85.7%. Conclusions: The continuous measurement of ScvO₂ values obtained by the Pediasat may provide useful information about the metabolic conditions of the brain during cardiac operations in pediatric patients if considered as percentage changes. Absolute values of ScvO₂ tend to overestimate the correspondent rSO₂ values.     

Risk of Complications of Atrial Fibrillation

Atrial fibrillation is associated with three major risk of complications: thromboembolism, hemodynamic compromise, and arrhythmogenesis. In patients with chronic atrial fibrillation the incidence of embolization is about 5% per year. The risk of embolism and in particular of stroke can be reduced by warfarine anticoagulation. Aspirin is generally less effective than warfarin, although it is probably more effective than placebo. The hemodynamic complications which may occur during atrial fibrillation are mainly due to the loss of effective atrial contraction, the irregular ventricular rhythm, and the possible excessively rapid ventricular rate. Sudden death is a recognized manifestation of Wolff-Parkinson-White syndrome and is considered to be precipitated by atrial fibrillation in the majority of patients. Torsades de pointes is perhaps the most widely recognized proarrhythmia associated with treatment of atrial fibrillation, especially with 1A antiarrhythmic drugs and sotalol. The chronic treatment with type 1C drugs in 3.5%–5% of patients may induce atrial flutter with 1:1 conduction with significant hemodynamic compromise.     

Three Years of Cardiac Resynchronization Therapy: Could Superior Benefits be Obtained in Patients with Heart Failure and Narrow QRS?

Aim of the study: To examine the long-term effects of cardiac resynchronization therapy (CRT) in patients presenting with heart failure (HF) and QRS ≤120 ms.
Methods: This was a prospective, longitudinal study of 376 patients [mean age = 65 years, mean left ventricular (LV) ejection fraction (EF) = 29%, mean QRS duration =165 ms, mean distance covered during a 6-minute hall walk (6-MHW) = 325 m], who underwent successful implantation of CRT systems. The QRS duration at baseline was ≤120 ms in 45 patients (12%) who were not pre-selected by echocardiographic criteria of dyssynchrony, and >120 ms in the remaining 331 patients. The baseline characteristics of the 2 groups were similar. We evaluated indices of cardiac function, percentage of responders, and survival rates over a mean 28-month follow-up.
Results: Both groups experienced similar long-term increases in 6-MHW, and decreases in New York Heart Association functional class and LV end-systolic volume (all comparisons P < 0.0001 in both groups). Time interaction of changes in LVEF and percentage of responders were significantly different (P = 0.03 and P = 0.004, respectively), in favor of the narrow QRS group, where the changes were sustained and persisted at 2 and 3 years. The long-term death rate from HF was lower in the group with narrow than in the group with wide QRS complex (P = 0.04; log-rank test).
Conclusions: CRT confers considerable long-term clinical, functional, and survival benefits in patients presenting with HF and narrow QRS, not preselected by echocardiographic criteria of dyssynchrony. Caution is advised before denying CRT to these patients on the basis of QRS width only.     

Postpartum Syncope

Recurrent unexpected syncope may have severe consequences and result in serious injury. This is especially the case in the immediate postpartum period when maternal syncope may have a disastrous effect on the infant as well as the mother. We report on 12 women who developed episodic hypotension resulting in syncope in the immediate postpartum period and describe the distinguishing characteristics of their presentation, tilt table results, and responses to therapy. Postpartum syncope represents a unique subgroup of syncopal patients who need to be recognized and treated in order to prevent potentially serious injury to both mother and infant.