Determinants of Efficacy of Atrial Pacing in Preventing Atrial Fibrillation Recurrences

Atrial Pacing in Atrial Fibrillation. Introduction: Several studies have shown that single or dual site atrial pacing is effective in reducing he frequency of recurrent atrial fibrillation (AF) in selected patients. However, it is still unclear what the best predictors are of long-term efficacy of atrial pacing. Methods and Results: Forty-seven patients with paroxysmal AF requiring demand pacing underwent electrophysiologic study and dual chamber pacemaker implant. After 4 months of follow-up, patients were divided into two groups according to the presence (group 1) or absence (group 2) of symptomatic AF recurrences. Atrial pacing markedly reduced AF recurrences in all patients. Twenty-four patients were free of arrhythmia. The basal state conduction times (CT_s) and the incremental conduction times (ICT_s), during programmed electric stimulation between the high right atrium (HRA) and the coronary sinus ostium (CS_os) but not between the HRA and the His-bundle region, were significantly longer in group 1. There was no statistical difference in the effective refractory period (ERP) recorded at the HRA, the low right atrium (LRA), and the CS_s between the two groups, whereas the differences between the greatest and least recorded ERPs measured from the HRA, LRA, and CS_os (δERP) were significantly greater in group 1 patients. Two parameters were selected by discriminant multivariate analysis, namely δCT_os (ICT-CT between HRA and CS_os and δERP. The first bad a greater relative importance in predicting AF recurrence (r²= 0.33 and r²= O.1, respectively). Conclusion: Single site atrial pacing is effective in reducing AF recurrences, with decreasing efficacy in patients with greater right atrial conduction delay and wider refractoriness dispersion.     

Worster-Drought syndrome: poorly recognized despite severe and persistent difficulties with feeding and speech

Aim  Worster-Drought syndrome (WDS), or congenital suprabulbar paresis, is a permanent movement disorder of the bulbar muscles causing persistent difficulties with swallowing, feeding, speech, and saliva control owing to a non-progressive disturbance in early brain development. As such, it falls within the cerebral palsies. The aim of this study was to describe the physical and neuropsychological profiles of children with WDS.
Method  Forty-two children with WDS (26 males, 16 females; mean age 7y 10mo, SD 3y 1mo; range 2y 6mo to 16y 5mo) were studied prospectively using a standard protocol.
Results  All of the children had severe bulbar dysfunction; 36 out of 42 had feeding difficulties and 23 of 38 had unintelligible speech, which was poorly compensated for by augmentative communication. There were accompanying disturbances in cognition (mean non-verbal IQ 59), behaviour (12/40 attention-deficit–hyperactivity disorder [ADHD]), social communication (8/42 autism), and epilepsy (12/39). The severity of bulbar dysfunction and impact of additional impairments made it difficult to use formal assessments.
Interpretation  WDS causes severe and persistent bulbar dysfunction that is often accompanied by additional impairments, as in other cerebral palsies. Speech prognosis is particularly poor. Early diagnosis with appreciation of the underlying neurology would encourage critical evaluation of interventions and long-term planning to improve outcome.     

FUNCTION AND SPECIFICITY OF HUMAN NATURAL KILLER CELL RECEPTORS

In humans, natural killer lymphocytes express HLA class I-specific inhibitory receptors belonging to at least two different molecular families. The first is represented by members of the Ig superfamily that are involved in the recognition of different groups of HLA class I alleles, and the second is represented by a molecular complex formed by CD94 and NKG2A that displays a broad specificity for various class I molecules including the ‘non-classical’ HLA-G molecules. In addition to the inhibitory receptors, a series of activating receptors has been identified. Some display the same specificities as the corresponding inhibiting receptors and can be viewed as HLA class I-specific activating receptors. Another group of activating receptors appear to be involved in the cytolytic activity against HLA-‘negative’ target cells. These receptors are clearly non-MHC specific and, under physiological conditions, their function is suppressed by the HLA class I-specific inhibitory receptors.     

Transesophageal Color Flow Echocardiographic Evaluation of Supravalve Mitral Ring in an Adult Patient

Supravalve mitral ring (SVMR) is an extremely rare form of congenital left ventricular inflow obstruction in which a left atrial membrane causes an obstruction keeping the left atrium from emptying into the left ventricle. Cardiac catheterization and angiography are not reliable means to diagnose this lesion. Transthoracic echocardiography (TTE) has proved to be the most sensitive tool for diagnosis of this form of left ventricular inflow obstruction; however, its diagnostic accuracy has been recently questioned. We report the complementary roles of TTE and transesophageal echocardiography in a case of SVMR in an adult patient. (ECHOCARDIOGRAPHY, Volume 11, May 1994)     

Long-term immunogenicity and safety of an inactivated hepatitis A vaccine in haemophilic patients

Summary. As a consequence of recent outbreaks of HAV infection by blood products, 91 patients, haemophiliacs and subjects with bleeding disorders (10 of whom were also anti-HIV positive) susceptible to HAV infection received a formalin-inactivated hepatitis A vaccine (HAVRIX 720 Elisa Units, SmithKline Beecham). Subcutaneous injections were given in the deltoid region at 0, 1 and 6 months. The seroconversion rates and litres, expressed in GMT IU/1, were determined at 1, 2, 6, 7, 12, 18 and 24 months. No adverse reactions to the vaccine were observed. The highest percentage of responders observed was 98.7% in anti-HIV negative and 71.4% in anti-HIV positive patients. The anti-HAV GMT titres were higher in anti-HIV negative than in anti-HIV positive patients. The inactivated hepatitis A vaccine is safe, clinically well tolerated, and provides long-term protection against HAV infection.     

Depth of sedation using Cerebral State Index in infants undergoing spinal anesthesia

Background: Infants are noted to frequently sleep during spinal anesthesia, with a concomitant fall in Bispectral Index. However, there are suggestions that EEG derived anesthesia depth monitors have inferior performance in infants. The aim of this study was to quantify the degree of sedation during spinal anesthesia in infants using another EEG derived measure of anesthesia effect – the Cerebral State Index (CSI). Methods: Twelve infants, <52 weeks postconceptual menstrual age, scheduled for bilateral inguinal hernia repair under spinal anesthesia were enrolled. Patients received a standard anesthetic protocol with a subarachnoid dose of 1 mg·kg^?1 of levobupivacaine 0.5%. No premedication, sedatives, opioids or anticholinergics were administrated during the perioperative period and patients were left undisturbed during the surgical time, without tactile stimulation or loud auditory stimuli. CSI score (0–100) and bust suppression (BS) (0–100%) were continuously recorded during the surgical time and then statistically re‐evaluated. Results: In all patients the CSI fell during the procedure and there were significant levels of BS recorded by the CSI monitor. The BS occurred between 12 and 34 min after spinal anesthesia with the peak being at 30 min and mean onset time being 15 (2.6) min after spinal block. A statistical significant difference was found between the lowest mean CSI as well as the highest BS if compared with their baseline values. A negative correlation was found between CSI and BS. Conclusions: The degree of burst suppression detected by the CSI in our study supports the hypothesis that infants may have discontinuous patterns of EEG during spinal anesthesia similar to those seen during emergence from general anesthesia. Moreover, the limitations in the application of the adult algorithms to infant EEG may lead to an overestimation of the degree of sedation.