Advanced Pacemaker Diagnostic Features in the Characterization of Atrial Fibrillation: Impact on Preventive Pacing Algorithms

YANG, A., et al .: Advanced Pacemaker Diagnostic Features in the Characterization of Atrial Fibrillation: Impact on Preventive Pacing Algorithms. Pacing algorithms to prevent PAF are mainly based on the suppression of premature atrial complexes (PACs), which play an important role in its initiation. In contrast to 24-hour ambulatory electrocardiograms, advanced pacemaker (PM) diagnostic features are capable of recording AF episodes during long follow-up periods and of characterizing AF in a detailed fashion. For the specific use of these algorithms, a detailed characterization of AF was performed in 91 dual chamber PM recipients with histories of AF. Fifteen patients with episodes of oversensing due to far-field signals or frequent episodes of "2:1-undersensing" of atrial flutter were excluded. The remaining 76 patients had high recurrence rates of AF (median 0.8 episodes/day), however, the majority of episodes lasted <7 minutes. Despite frequent PACs (median 10.8/hour) during sinus rhythm, a median of 66.4% of the AF episodes were preceded by <2 PACs/min before onset. In conclusion, frequent, short-lived AF episodes seem best suited for AF preventive pacing therapies. However, the small number of PACs preceding many AF episodes may limit the efficacy of PAC suppressing algorithms. (PACE 2003; 26[Pt. II]:310–313)     

Arrhythmia Risk: Eiectrophysiological Studies and Monophasic Action Potentials

Shortly after in the introduction of progrommed electrical stimulotion (PES) of the heart to study and localize cardiac arrhythmias in the intact human heart, the technique was used for risk stratification of the arrhythmia patient. Two decades later we have to conclude that especially in ventricular arrhythmias the technique of PES did not live up to our expectations and the left ventricular function is a better long-term predictor than the induction of ventricular arrhythmias or the ability to find an antiarrhythmic drug able to prevent the initiation of the classically documented ventricular arrhythmia. Another sobering finding come from the analysis of the characteristics of the patient dying suddenly out-of-hospital, which showed that most of those patients could not be classified before the event as being at high risk using noninvasive or invasive testing, not even in those with o previous cardiac history. Monomorphic action potential (MAP) recordings have been of importance in our understanding of torsade de pointe arrhythmias in congenital and acquired QT prolongation. A major problem in case of a less generalized electrophysiological abnormality is the identification of the appropriate place where to put the MAP-electrode.     

Radiofrequency Catheter Ablation of an Accessory Pathway in a Young Man with Dextroversion

We report an observation of a radiofrequency catheter ablation of an accessory pathway (AP) in a patient with Wolff-Parkinson-White syndrome (WPW) and dextroversion. Atrioventricular rings were mapped by the ablation catheter to locate the shortest local atrioventricular conduction time in sinus rhythm and ventriculoatrial conduction time during orthodromic tachycardia or ventricular pacing. Successful ablation confirmed a right posteroseptal AP localization. Thus, the electrocardiographic modifications due to an AP in this location in the presence of dextroversion were defined.     

Is adenoidectomy in children safer with laryngeal mask airway or with tracheal intubation?

Adenoidectomy in paediatric outpatient surgery is assumed to require tracheal intubation (TT). The laryngeal mask airway (LMA) commonly used for general paediatric surgery has never been previously studied for adenoidectomy. We therefore prospectively compared in a randomized manner, the incidence of complications with TT and LMA in 56 children undergoing adenoidectomy. Preoperative, intraoperative and the lowest SPO₂ values after removal of either TT or LMA were recorded. The respiratory complications, cough, stridor and/or laryngospasm, were recorded intraoperatively and after removal of the airway device. The oxygen saturation levels were significantly higher in the laryngeal mask airway group both intraoperatively and after removal of the respiratory device (P<0.05). The incidence of respiratory complications was lower in the LMA group. In conclusion we have shown that the laryngeal mask airway with a flexometallic tube is a satisfactory alternative to tracheal intubation for outpatient paediatric adenoidectomy.     

An evaluation of the history of a marijuana withdrawal syndrome in a large population

Case reports and laboratory research indicate the existence of a cannabis withdrawal syndrome. However, the data tell us little about the prevalence and clinical characteristics of a marijuana withdrawal syndrome in people who have used the drug but who did not enter treatment for cannabis dependence. Face-to-face semi-structured interviews applying standard diagnostic criteria were used in the present study to gather data from 5611 men and women, recruited between 1991 and 1995 through the Collaborative Study of the Genetics of Alcoholism (COGA). Almost 41% of the sample had no history of marijuana use (Group 1), 28% had consumed this drug less than 21 times in any single year (Group 2), and 3t% used it at least that frequently (Groups 3 and 4). Almost 16% of the more frequent marijuana users related a history of a marijuana withdrawal syndrome, and these Group 4 subjects had used the drug almost daily for an average of almost 70 months. The typical withdrawal symptoms included “nervous, tense, restlessness”, “sleep disturbance” and “appetite change”. While Group 4 subjects were more likely to have developed dependence on most types of drugs, even when alcohol and drug use patterns were statistically taken into account, marijuana use was still significantly related to a self-report of a history of marijuana withdrawal.     

MOLECULAR GENETICS OF ACTIVITY-DEPENDENT STRUCTURAL CHANGES AT THE SYNAPSE

Antibodies to horseradish peroxidase (HRP) recognize 27 of 302 neurons and several non-neuronal cells in adult hermaphrodites of the soil nematode Caenorhabditis elegans and can be used to label these cells for cytological analysis in whole animals. The antibodies bind to the anterior members, but not to the posterior members of a set of mechanosensory neurons in wild type animals. Binding to one of the posterior mechanosensory neurons (PVM) occurs when this neuron migrates to an abnormal anterior position in mab-5 mutant animals, suggesting that expression of the epitope recognized by these antibodies is position dependent or that mab-5 mutations transform PVM into AVM intrinsically. The antibodies were used to characterize morphologies of two pairs of lumbar neurons (PHC and PVN) in uncoordinated mutants representing 95 unc genes. PHC and PVN morphologies were normal in most of the unc mutants examined, however, in mutants of 9 unc genes (unc-6, unc-13, unc-33, unc-44, unc-51, unc-61, unc-71, unc-73, and unc-98), misdirected PHC and/or PVN processes were observed at a high frequency. The morphologies of 2 other lumbar neurons, PHA and PHB, were determined previously in these mutants (Hedgecock et al., 1985). Mutations in most, but not all of these 9 unc genes affect the growth of the embryonic lumbar neurons PHA and PHB differently than they affect the growth of the postembryonic lumbar neurons PHC and PVN, indicating that these neurons require different, but overlapping sets of genes for different stages of normal growth and guidance.     

Challenges,Successes, and the Future of Firearm Injury Prevention

Policy Points

• Firearm injury is a leading cause of death in the United States, with fatality rates increasing 34.9% over the past decade (2010-2020).
• Firearm injury is preventable through multifaceted evidence-based approaches.
• Reviewing past challenges and successes in the field of firearm injury prevention can highlight the future directions needed in the field.
• Adequate funding, rigorous and comprehensive data availability and access, larger pools of diverse and scientifically trained researchers and practitioners, robust evidence-based programming and policy implementation, and a reduction in stigma, polarization, and politicization of the science are all needed to move the field forward.