Three-Year Experience with a Stylet for Lead Extraction: A Multicenter Study

The extraction of chronically implanted and infected pacemaker and defibrillator leads is an important issue. This article describes the experience gathered between 1990 and 1994 by seven European centers regarding a locking stylet that is uniformly applicable for a wide variety of internal pacing coil diameters. This interventional locking stylet for lead extraction has an outer diameter of 0.4 mm (0.016 inches). The stylet consists of a hollow shaft in which an inner traction wire is embedded. At the tip of the inner traction wire an anchoring mechanism, which can be opened by retraction, is applied. Removal attempts were made for 150 leads, 110 in ventricular and 40 in atrial positions. Results : Complete removal was possible in 122 cases (81 %). Partial removal was possible in 18 cases (12%). Failure to remove the lead with the extraction stylet was experienced in 10 cases (7%). In seven patients, the leads were removed by cardiothoracic surgery; 3 defective leads were left in place. There were no serious complications associated with the procedure. None of the patients died. Conclusion : The experience with this extraction stylet for lead removal has shown good results. Despite a low complication rate thus far, each case for lead removal should be judged on the individual basis of benefit-to-risk ratio.     

Programmable VT Detection Enhancements in Implantable Cardioverter Defibrillator Therapy

This report describes the distribution of automatically measured values of enhanced arrhythmia detection parameters such as “rate stability” and “rate onset” in various forms of spontaneous arrhythmia episodes in patients treated with a new, third-generation, tiered therapy implantable cardioverter defibrillator (ICD). The study population consisted of 27 patients who received the Ventak PRxII cardioverter defibrillator, which provides extensive diagnostic options such as electrogram storage capabilities, and the ability to store measured values of additional arrhythmia detection parameters such as rate stability and rate onset during spontaneous arrhythmia episodes. During a follow-up period of 11.1 ± 5.2 months, this device detected 264 arrhythmia episodes. The analysis of stored electrograms revealed 13 episodes of sinus tachycardia, 52 episodes of atrial tachyarrhythmias, and 201 episodes of monomorphic ventricular tachycardias (VTs). The mean measured values of rate stability and rate onset were: 2.2 ± 0.9 msec, 0% in sinus tachycardias; 41.0 ± 24.1 msec, 8.5%± 9.5% in atrial tachyarrhythmias; and 7.8 ± 6.0 msec, 30.6%± 12.1% in monomorphic VTs. There was a wide zone of overlapping measured values for rate stability and rate onset in ventricular and nonventricular rhythms. No episode of VT showed a measured rate stability criterion > 35 msec. The subanalysis of arrhythmia episodes presenting with a heart rate < 160 beats/mm revealed no episode of VT with a rate stability value > 24 msec. The calculated, rate dependent specificities for these programmed rate stability parameters in detecting VTs were 46.2% and 81.8%, respectively. The analysis of the rate onset algorithm revealed no comparable relationship between sensitivity and specificity in the detection of VTs. Additional arrhythmia detection algorithms such as rate stability and rate onset may contribute to a significant enhancement in the specificity of lCD therapy.     

无机活性元素骨组织工程支架材料修复山羊颌骨缺损

目的:应用无机活性元素骨组织工程支架材料,对山羊的下颌骨角部大型箱状缺损施行骨重建,观察支架材料骨构建效能和生物相容性的情况。方法:实验于2004-02/12在安徽医科大学附属省立医院实验中心及相关实验室完成。①实验材料:无机活性元素骨组织工程支架材料由美国波士顿大学分子生物相容学研究室研制提供;21只雌性健康山羊由安徽医科大学动物实验中心(皖医实动准字01号)提供,实验过程中动物处置符合动物伦理学标准。②实验方法:取山羊15只,按4,8,12周3个时间点分为3组,位下颌角部手术制备30 mm×25 mm×10 mm的大型箱状缺损。采用自身配对设计,左侧置入支架材料为实验组,右侧空白对照为对照侧;剩余6只山羊为对照组,不手术。③观察指标:术后4,8,12周应用X射线片、组织学和放射性核素显像观察缺损区新骨形成情况;并测定骨密度;应用血液学检查及骨髓基质细胞体外复合细胞培养评价材料的生物相容性。结果:①一般观察:实验山羊无手术死亡,创口Ⅰ期愈合。②X射线片:实验侧有渐进性骨密度增高,阻射影逐级增强,对照侧呈透光阴影。③放射性核素显像:实验侧有较明显的核浓聚和再生血管化现象,对照侧无骨重建,故无骨代谢变化。④骨密度测量系数:实验侧呈递增式上升,对照侧维持较低水平,提示无自发性成骨。⑤组织学观察:实验侧呈时间递增性骨重建现象,在12周时新骨已完全形成并钙化基本完成,而对照侧直到12周仍无成骨现象。⑥生物相容性:各组的血常规、细胞形态、生化和相关酶学指标均在正常范围内。结论:无机活性元素骨组织工程支架材料有良好的成骨和再血管化功能,且生物相容性好,提示由该支架材料诱导的组织工程化骨构建有望成为临床骨组织大型缺损的替代材料。     

Sumatriptan inhibits neurogenic vasodilation of dural blood vessels in the anaesthetized rat-intravital microscope studies

This study used intravital microscopy to measure the diameter of dural arteries in anaesthetized rats. Electrical stimulation of the surface of a closed cranial window produced increases in dural vessel diameter which were blocked by the CGRP receptor antagonist human-CGRP_(8–37) but unaffected by the NK1 receptor antagonist RP67580. Sumatriptan (3 and 0 mg kg⁻¹, iv) significantly reduced the response to electrical stimulation. In contrast, sumatriptan (3 mg kg⁻¹) had no effects on the response to exogenously administered CGRP. These results indicate that neurokinins play no role in neurogenic vasodilation in this preparation and that neurogenic vasodilation in rat dural vessels is mediated predominantly by CGRP. Furthermore, the data indicate that sumatriptan attenuates neurogenic vasodilation, probably by inhibiting the release of CGRP from perivascular trigeminal nerve endings innervating the dura. These experimental data parallel the clinical findings that CGRP levels are elevated in migraine and normalized, concomitantly with headache relief, by sumatriptan.     

An evidence‐based review of split‐thickness skin graft donor site dressings

This evidence‐based review aimed to identify and evaluate current existing evidence relating to the efficacy of dressing materials for spit‐thickness skin graft donor site wounds in relation to promoting rapid healing and reducing patient pain. A comprehensive systematic search of the literature between 2006 and 2016 identified 35 publications that were included in the review.Based on the results of the review, it was found that moist wound‐healing products have a clear advantage over non‐moist products in the reduction of pain and increased healing rates. This review concluded that moist wound‐healing products are more effective than non‐moist wound‐healing products in reducing pain and promoting healing in split‐thickness skin graft donor site wounds. A recommendation based on this review is that further research examine the role of secondary dressing usage in donor site wound management, and the consideration of using more than one primary dressing product during the donor site wound‐healing process should be undertaken.     

Correlation of fluconazole MICs with clinical outcome in cryptococcal infection

We have correlated the in vitro results of testing the susceptibility of Cryptococcus neoformans to fluconazole with the clinical outcome after fluconazole maintenance therapy in patients with AIDS-associated cryptococcal disease. A total of 28 isolates of C. neoformans from 25 patients (24 AIDS patients) were tested. The MICs were determined by the broth microdilution technique by following the modified guidelines described in National Committee for Clinical Standards (NCCLS) document M27-A, e.g., use of yeast nitrogen base medium and a final inoculum of 10(4) CFU/ml. The fluconazole MIC at which 50% of isolates are inhibited (MIC(50)) and MIC(90), obtained spectrophotometrically after 48 h of incubation, were 4 and 16 microg/ml, respectively. Of the 25 patients studied, 4 died of active cryptococcal disease and 2 died of other causes. Therapeutic failure was observed in five patients who were infected with isolates for which fluconazole MICs were > or =16 microg/ml. Four of these patients had previously had oropharyngeal candidiasis (OPC); three had previously had episodes of cryptococcal infection, and all five treatment failure patients had high cryptococcal antigen titers in either serum or cerebrospinal fluid (titers, >1:4,000). Although 14 of the 18 patients who responded to fluconazole therapy had previously had OPC infections, they each had only a single episode of cryptococcal infection. It appears that the clinical outcome after fluconazole maintenance therapy may be better when the infecting C. neoformans strain is inhibited by lower concentrations of fluconazole for eradication (MICs, <16 microg/ml) than when the patients are infected with strains that require higher fluconazole concentrations (MICs, > or =16 microg/ml). These findings also suggest that the MICs determined by the modified NCCLS microdilution method can be potential predictors of the clinical response to fluconazole therapy and may aid in the identification of patients who will not respond to fluconazole therapy.     

Inexpensive 4-hour micro-agar dilution susceptibility determination method.

Using a micro-agar dilution (MAD) method in which microscope slides are covered with a thin film of agar, and MICs are read microscopically after a 4-h incubation, 18 antibiotics were tested against 29 to 32 microorganisms each. Identical MICs were obtained for microscopic MAD MICs performed in duplicate in 87.1% of the antibiotic-microorganism combinations, and 97.9% were identical within one dilution. When read macroscopically after an 18-h incubation, identical duplicate MICs were obtained in 86.8% of the cases, and 98.4% were identical within one dilution. Using agar dilution as the "gold standard," the correlation obtained with MAD slides read microscopically at 4 h was 94.3%, and macroscopic correlation at 18 h was 97.6%. The correlation of MAD slides with agar dilution for the groups of microorganisms most frequently used was as follows (microscopic/macroscopic): Staphylococcus aureus 96%/98%; Streptococcaceae 97%/98%; Enterobacteriaceae 98%/99%; and Pseudomonadaceae 95%/98%. At the present rate of exchange (fl 1.60 = $1.00f1p4he cost of a MAD slide, including labor, is $1.28 (20 microorganisms tested) or $0.06 per microorganism-antibiotic combination tested. This method is easy to perform, rapid, and inexpensive. It is suitable for use in routine and research laboratories.     

Paraduodenal herniation: An internal herniation in a virgin abdomen

INTRODUCTION

A paraduodenal hernia is an uncommon hernia that results from an abnormal rotation of the midgut. Commonly, these hernias are congenital in nature, and are reported to cause 1.5–5.8% of intestinal obstructions. These hernias occur when a part of the jejunum herniates through the posterior portion of the ligament of Treitz. Diagnosing these hernias preoperatively has been shown to be difficult, despite the studies that are available. Early diagnosis is imperative to the patient in order to avoid strangulation of the bowel, which is associated with a high mortality.

PRESENTATION OF CASE

In this case, we present a case of a left-sided paraduodenal hernia in a virgin abdomen in a 38-year-old African American male with a herniation of a loop of jejunum through a defect of the posterior portion of the ligament of Treitz. The patient also had a volvulized segment of the proximal jejunum, and part of this bowel was found to be ischemic.

DISCUSSION

Acute intestinal obstruction caused by a left paraduodenal hernia is a rare cause of intestinal obstruction. A literary search of PubMed between 1980 and 2012 indicated only 44 cases of intestinal obstruction secondary to a left paraduodenal hernia.

CONCLUSION

The patient underwent exploratory laparotomy, and the herniated bowel was found to be ischemic. The hernia was reduced, and the ischemic bowel resected. The defect was closed, and the patient had a non-complicated recovery.     

Project HOPE: Online Social Network Changes in an HIV Prevention Randomized Controlled Trial for African American and Latino Men Who Have Sex With Men

Objectives. We examined whether and how an HIV prevention diffusion-based intervention spread throughout participants’ online social networks and whether changes in social network ties were associated with increased HIV prevention and testing behaviors.Methods. We randomly assigned 112 primarily racial/ethnic minority men who have sex with men (MSM) to receive peer-delivered HIV (intervention) or general health (control) information over 12 weeks through closed Facebook groups. We recorded participants’ public Facebook friend networks at baseline (September 2010) and follow-up (February 2011), and assessed whether changes in network growth were associated with changes in health engagement and HIV testing.Results. Within-group ties increased in both conditions from baseline to follow-up. Among the intervention group, we found a significant positive relation between increased network ties and using social media to discuss sexual behaviors. We found a positive trending relationship between increased network ties and likelihood of HIV testing, follow-up for test results, and participation in online community discussions. No significant differences were seen within control groups.Conclusions. Among high-risk MSM, peer-led social media HIV prevention interventions can increase community cohesion. These changes appear to be associated with increased HIV prevention and testing behaviors.African American and Latino individuals are at high risk for contracting HIV.1 In Los Angeles County, California, most of these cases are attributable to men who have sex with men (MSM), who currently account for more than 75% of all HIV cases.2,3 Researchers, and MSM themselves, have suggested use of novel approaches to increase HIV prevention and testing among at-risk populations.4,5Peer leader interventions, based on diffusion theories, are community-based interventions that train community peers to spread HIV prevention information and change HIV prevention-related social norms.6–9 Successful peer-led interventions have resulted in decreasing anal intercourse up to 25% and increasing condom use up to 16%, with sustained behavior change up to 3 years later.10–12 Peer-delivered interventions have been found to be acceptable among MSM populations.13 Social network interventions have shown that information can rapidly diffuse throughout social networks to change health behaviors,14,15 suggesting that peer-delivered HIV interventions also might diffuse throughout social networks.Growth in social media allows these technologies to be used for peer-led HIV testing interventions,4 and research supports that peer-led interventions delivered via social media can increase HIV testing.16 Social networking technologies, such as Facebook, allow users to connect and communicate with other network users by sharing pictures, messages, Web site links, and other multimedia information.17 High rates of online social networking, especially among groups disproportionately affected by HIV (e.g., MSM),18 make it important to evaluate whether and how interventions might diffuse throughout online social networks. Although social media can be used to increase HIV prevention,16,19,20a and health behaviors of (offline) social ties influence our own health behaviors20b, no known research has studied changes in social network ties during the course of an online social media community HIV intervention or whether and how HIV prevention information and behaviors might spread among group participants in a social media–based HIV testing intervention that is designed for network diffusion.The Harnessing Online Peer Education (HOPE) intervention was a 12-week randomized controlled HIV prevention intervention designed to use peer-led Facebook groups to diffuse HIV information to increase testing among African American and Latino MSM. The study found that participants in the HIV intervention groups were more likely to request an HIV test than were those in the control groups,16 but whether changes in social network ties (i.e., participants within each group becoming Facebook friends with one another) played a role in these effects among intervention group participants is unknown. The current study used data from the HOPE study and was designed to evaluate the association between changes in online social network structure and HIV prevention and testing among HOPE network participants. Specifically, we have (1) described the change from baseline to follow-up in network ties among HOPE participants as a result of the intervention, (2) presented network visualizations to illustrate changes in network connections among intervention and control group participants, and (3) determined whether changes in social network ties from baseline to follow-up were associated with online community engagement, discussions about HIV prevention, and rates of HIV testing.     

Normal variation of magnetic resonance T1 relaxation times in the human population at 1.5 T using ShMOLLI

Background

Quantitative T1-mapping is rapidly becoming a clinical tool in cardiovascular magnetic resonance (CMR) to objectively distinguish normal from diseased myocardium. The usefulness of any quantitative technique to identify disease lies in its ability to detect significant differences from an established range of normal values. We aimed to assess the variability of myocardial T1 relaxation times in the normal human population estimated with recently proposed Shortened Modified Look-Locker Inversion recovery (ShMOLLI) T1 mapping technique.

Methods

A large cohort of healthy volunteers (n = 342, 50% females, age 11–69 years) from 3 clinical centres across two countries underwent CMR at 1.5T. Each examination provided a single average myocardial ShMOLLI T1 estimate using manually drawn myocardial contours on typically 3 short axis slices (average 3.4 ± 1.4), taking care not to include any blood pool in the myocardial contours. We established the normal reference range of myocardial and blood T1 values, and assessed the effect of potential confounding factors, including artefacts, partial volume, repeated measurements, age, gender, body size, hematocrit and heart rate.

Results

Native myocardial ShMOLLI T1 was 962 ± 25 ms. We identify the partial volume as primary source of potential error in the analysis of respective T1 maps and use 1 pixel erosion to represent “midwall myocardial” T1, resulting in a 0.9% decrease to 953 ± 23 ms. Midwall myocardial ShMOLLI T1 was reproducible with an intra-individual, intra- and inter-scanner variability of ≤2%. The principle biological parameter influencing myocardial ShMOLLI T1 was the female gender, with female T1 longer by 24 ms up to the age of 45 years, after which there was no significant difference from males. After correction for age and gender dependencies, heart rate was the only other physiologic factor with a small effect on myocardial ShMOLLI T1 (6ms/10bpm). Left and right ventricular blood ShMOLLI T1 correlated strongly with each other and also with myocardial T1 with the slope of 0.1 that is justifiable by the resting partition of blood volume in myocardial tissue. Overall, the effect of all variables on myocardial ShMOLLI T1 was within 2% of relative changes from the average.

Conclusion

Native T1-mapping using ShMOLLI generates reproducible and consistent results in normal individuals within 2% of relative changes from the average, well below the effects of most acute forms of myocardial disease. The main potential confounder is the partial volume effect arising from over-inclusion of neighbouring tissue at the manual stages of image analysis. In the study of cardiac conditions such as diffuse fibrosis or small focal changes, the use of “myocardial midwall” T1, age and gender matching, and compensation for heart rate differences may all help to improve the method sensitivity in detecting subtle changes. As the accuracy of current T1 measurement methods remains to be established, this study does not claim to report an accurate measure of T1, but that ShMOLLI is a stable and reproducible method for T1-mapping.