Kinetics of atrial repolarization alternans in a free-behaving ovine model

Kinetics of Atrial Repolarization Alternans. Introduction: Repolarization alternans (Re‐ALT), a beat‐to‐beat alternation in action potential repolarization, promotes dispersion of repolarization, wavebreaks, and reentry. Recently, Re‐ALT has been shown to play an important role in the transition from rapid pacing to atrial fibrillation (AF) in humans. The detailed kinetics of atrial Re‐ALT, however, has not been reported so far. We developed a chronic free‐behaving ovine pacing model to study the kinetics of atrial Re‐ALT as a function of pacing rate. Methods: Thirteen sheep were chronically implanted with 2 pacemakers for the recording of broadband right atrial unipolar electrograms and delivery of rapid pacing protocols. Beat‐to‐beat differences in the atrial T‐wave apex amplitude as a measure of Re‐ALT and activation time were analyzed at incremental pacing rates until the effective refractory period (ERP) defined as stable 2:1 capture. Results: Atrial Re‐ALT appeared intermittently but without periodicity, and increased in amplitude as a function of pacing rate until ERP. Intermittent 2:1 atrial capture was observed at pacing cycle lengths 40 ms above ERP, and increased in duration as a function of pacing rate. Episodes of rapid pacing‐induced AF were rare, and were preceded by Re‐ALT or complex oscillations of atrial repolarization, but without intermittent capture. Conclusion: We show in vivo that atrial Re‐ALT developed and increased in magnitude with rate until stable 2:1 capture. In rare instances where capture failure did not occur, Re‐ALT and complex oscillations of repolarization surged and preceded AF initiation. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1003‐1012, September 2012)     

Significant reduction in systolic blood pressure following renal artery stenting in patients with uncontrolled hypertension: Results from the HERCULES trial

Background : Atherosclerotic renal artery stenosis (ARAS) causes hypertension (HTN) and threatens renal function (RF). The HERCULES Trial is a prospective, multicenter trial of renal stenting in patients with uncontrolled HTN and ARAS evaluating the safety and effectiveness of the RX Herculink Elite Renal Stent System (Abbott Vascular, Santa Clara, CA). Results : Mean systolic blood pressure (SBP) at baseline was 162 mm Hg. Nearly 70% of patients were receiving three or more antihypertensive medications (mean 3.4 medications per patient). Baseline serum creatinine was 1.2 ± 0.4 and 61.5% of subjects had estimated glomerular filtration <60. The restenosis rate was 10.5% at 9 months. The study device, procedure, and clinical success rates were 96.0, 99.2, and 98.0%, respectively. Freedom from major adverse events was 94.8%. At 9 months, the mean SBP significantly decreased (mean 145, paired t test P < 0.0001) after stenting with no change in medications. There was no correlation between SBP reduction and baseline BNP or BNP reduction. 相似文献   

Impact of accreditation on documentation and staff perception in the ophthalmology department of an Indian medical college

Purpose:National Accreditation Board for Hospitals and Healthcare Providers operates the health-care accreditation program in India. Research on impact of accreditation on eye-care centers is scarce. This article was conceptualized to scientifically evaluate the changes in documentation brought about by accreditation and its effects on staff in the Ophthalmology Department of an Indian Medical College.Methods:This was conducted as a quasi-experimental study in four steps. First, a point-based evaluation of case sheets in both pre-accreditation and postaccreditation phase, along with statistical analysis of the results, was done. Step two involved analysis of quality indicators and patient safety indices in successive years from inception of data to post-accreditation phase. Step three comprised a survey of staff employing a validated tool, and finally, face-to-face semistructured interviews with designated authorities, including finance departmental head, completed the study.Results:A statistically significant difference was seen in scores achieved by the pre and postaccreditation case sheets, with the postphase case sheets achieving 15% increased scores over the prephase case sheets. Quality indicator indices displayed improvements post-accreditation. There was an accompanying increase in quantity of documentation. Financial data analysis showed increased expenditure for accreditation under multiple heads. Staff believed that accreditation led to increased workload but did not express decreased satisfaction and felt that accreditation was eventually beneficial. However, staff believed rewards for improving quality can be enhanced.Conclusion:Accreditation increases quality and quantity of documentation, and staff workload. Increased financial costs also ensue.Staff believe that accreditation improves quality, is beneficial, but desire enhanced rewards.