AV Delay and Exercise Stress Tests: Behavior in Normal Subjects

BARBIERI, D., ET AL.: AV Delay and Exercise Stress Tests: Behavior in Normal Subjects. In normal subjects the atrioventricular (AV) conduction is accelerated during exertion. The relationship between heart rate and AV delay is usually described as "linear". Looking at the increasing importance given to an appropriate AV synchrony in permanent dual chamber and P synchronous pacing we present the results of an investigation performed to study the correlation between AV conduction time and heart rate under stress conditions, and disclose some new aspects of this matter, which will possibly be useful for a further improvement of pacemaker technology.     

SR 48968 selectively prevents faecal excretion following activation of tachykinin NK2 receptors in rats*

Abstract— We tested the ability of SR 48968, (S)-N-methyl-N(4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophenyl)butyl)benzamide, a non-peptide antagonist highly selective for tachykinin NK₂ receptors, to prevent defecation induced in rats by several agents. The tachykinin agonists substance P, [MePhe⁷]neurokinin B and [β-Ala⁸]neurokinin A (4–10) all promoted defecation and increased faecal water content, the last compound being over ten times more potent than the other two (intraperitoneal dose inducing the excretion of I g faeces dry weight = 6·7 μg kg^?1). SR 48968 given either orally (p.o.) or subcutaneously (s.c.) was similarly potent in dose-dependently inhibiting faecal output stimulated by the selective NK₂-agonist [β-Ala⁸]neurokinin A (4–10) (doses causing 50% inhibition 0·4 μg kg^?1, p.o. and 0·3 μg kg^?1, s.c). This inhibition was long-lasting (more than 18 h after 1 μg kg^?1 SR 48968 either s.c. or p.o.). At the higher doses tested, SR 48968 also significantly prevented the increase in faecal water content produced by [β-Ala⁸]neurokinin A (4–10). In rats treated with SR 48968, stimulation of faecal output by the α₂-adrenergic antagonist idazoxan and by salmonella endotoxin (LPS), but not by the 5-HT_1A agonist 8-hydroxy-2-(di-n-propylamino) tetralin, 5-HT, carbachol or platelet-activating factor, was partially prevented. The present results suggest that activation of intestinal NK₂ receptors, either directly by the selective agonist [β-Ala⁸]neurokinin A (4–10) or indirectly through the release of endogenous neurokinin A (by idazoxan or LPS), promotes defecation, presumably as a consequence of increased gut motility or secretion, or both. SR 48968 should therefore be useful for studying the role of neurokinin A-dependent mechanisms in health and disease, including those of the gastrointestinal system, and possibly for developing new therapeutic agents.     

AV Delay Optimization and Management of DDD Paced Patients with Dilated Cardiomyopathy

Ten DDD paced patients, suffering front dilated cardiomyopathy in the NYHA functional classes III or IV were studied by means of Doppler ecbocardiography at different programmed values of atrioventricular (AV) delay (200, 150, 120, 100, and 80 msec). The following variables were evaluated: LV diameter, ejection fraction, mitral and aortic flow velocity integrals, and stroke volume. During VDD pacing, a resting AV delay associated with the best diastolic filling and systolic function was identified and programmed individually. Shortening of the AV delay to about 100 msec was associated with a gradual and progressive improvement. Further decrease caused an impairment of systolic function. The patients were clinically and beinodynamically reevaluated after 2 months of follow-up. A reduction of NYHA class and an improvement of LV function were consistently found. The reported data suggest that programming of an optimal A V delay may improve myocardial function in DDD paced patients with congestive heart failure. This result may be the consequence of an optimization of left ventricular filling and a better use of the Frank-Starling law.     

A Prospective Multicenter Study Evaluating Loading of Osseotite Implants Two Months After Placement: One-Year Results

Abstract: Historically, the recommended time between placement and functional loading of machined-surface dental implants has been 3 months for the mandible and 6 months for the maxilla. However, such recommendations are a result of evaluating randomly chosen healing times during the initial phase of implant development and are based on the subsequent clinical outcome of either implant integration or mobility. In recent years, histologic and experimental studies have shown that specifically designed micro-topographic implant surfaces can result in increased bone-to-implant contact at earlier healing times than obtained with machined-surface implants. Histologic and clinical studies investigating early and immediate implant loading support the premise that implants can be placed into function earlier than previously recommended. With the development of specifically designed implant surfaces and the utilization of time-saving surgical (one-stage surgical protocol) and prosthetic (implant position indexing) techniques, patients are now being restored and returning to function sooner than previously thought possible. The purpose of this multicenter clinical investigation is to evaluate the efficacy of loading Osseotite dental implants (3i-Implant Innovations Inc., Palm Beach Gardens, Florida) at 2 months and to determine the effect of early loading on implant performance and survival. A total of 429 Osseotite implants were placed in 155 patients (87 females and 68 males; mean age 54.0 ± 13.7 yr), at 10 study centers, and subsequently loaded 2.1 ± 0.7 months following placement. A single-stage surgical protocol was followed, with implants indexed immediately or impressed 4 to 6 weeks following placement. Patient restorative treatments included placement of 83 single-implant provisional restorations and 129 splinted, two-, three-, and four-implant supported maxillary and mandibular provisional restorations. The mean time from prosthetic loading to the most recent follow-up evaluation was 10 ± 1.3 months. Seven of the 429 implants did not integrate; of these, six were identified prior to loading and one was identified 1 month after loading. The cumulative implant survival rate was 98.5% at 12.6 months. The cumulative post-loading implant survival rate was 99.8% at 10.5 months. The preliminary results of this clinical investigation suggest that successful functional loading of the Osseotite dental implant is possible at 2 months following noncomplicated implant placement.     

Combined Left Atrial Appendage Closure and Pacemaker Implant through a Single Right Femoral Vein Access

Left atrial appendage (LAA) closure is indicated in patients with atrial fibrillation (AF) and high bleeding as well as thromboembolic risks. A subgroup of these patients may also present an indication for a single‐chamber permanent pacemaker due to symptomatic low‐rate AF or when “ablate and pace” strategy is indicated for rate control. A miniaturized wireless transcatheter pacing system (TPS) is now available as a single‐chamber permanent pacemaker. This case presents how combined LAA closure and permanent pacemaker implant, by means of TPS, is feasible through a single femoral venous access.