Length of the Mitral Isthmus But Not Anatomical Location of Ablation Line Predicts Bidirectional Mitral Isthmus Block in Patients Undergoing Catheter Ablation of Persistent Atrial Fibrillation: A Randomized Controlled Trial

INTRODUCTION Mitral isthmus (MI) ablation is an effective option in patients undergoing ablation for persistent atrial fibrillation (AF). Achieving bidirectional conduction block across the MI is challenging, and predictors of MI ablation success remain incompletely understood. We sought to determine the impact of anatomical location of the ablation line on the efficacy of MI ablation. METHODS AND RESULTS A total of 40 consecutive patients (87% male; 54 ± 10 years) undergoing stepwise AF ablation were included. MI ablation was performed in sinus rhythm. MI ablation was performed from the left inferior PV to either the posterior (group 1) or the anterolateral (group 2) mitral annulus depending on randomization. The length of the MI line (measured with the 3D mapping system) and the amplitude of the EGMs at 3 positions on the MI were measured in each patient. MI block was achieved in 14/19 (74%) patients in group 1 and 15/21 (71%) patients in group 2 (P = NS). Total MI radiofrequency time (18 ± 7 min vs. 17 ± 8 min; P = NS) was similar between groups. Patients with incomplete MI block had a longer MI length (34 ± 6 mm vs. 24 ± 5 mm; P < 0.001), a higher bipolar voltage along the MI (1.75 ± 0.74 mV vs. 1.05 ± 0.69 mV; P < 0.01), and a longer history of continuous AF (19 ± 17 months vs. 10 ± 10 months; P < 0.05). In multivariate analysis, decreased length of the MI was an independent predictor of successful MI block (OR 1.5; 95% CI 1.1-2.1; P < 0.05). CONCLUSIONS Increased length but not anatomical location of the MI predicts failure to achieve bidirectional MI block during ablation of persistent AF.

Modelling the impact of deferring HCV treatment on liver-related complications in HIV coinfected men who have sex with men

BACKGROUND AND AIMS Hepatitis C (HCV) is a leading cause of morbidity and mortality in people who live with HIV. In many countries, access to direct acting antiviral agents to treat HCV is restricted to individuals with advanced liver disease (METAVIR stage F3 or F4). Our goal was to estimate the long term impact of deferring HCV treatment for men who have sex with men (MSM) who are coinfected with HIV and often have multiple risk factors for liver disease progression. METHODS We developed an individual-based model of liver disease progression in HIV/HCV coinfected men who have sex with men. We estimated liver-related morbidity and mortality as well as the median time spent with replicating HCV infection when individuals were treated in liver fibrosis stages F0, F1, F2, F3 or F4 on the METAVIR scale. RESULTS The percentage of individuals who died of liver-related complications was 2% if treatment was initiated in F0 or F1. It increased to 3% if treatment was deferred until F2, 7% if it was deferred until F3 and 22% if deferred until F4. The median time individuals spent with replicating HCV increased from 5 years if treatment was initiated in F2 to almost 15 years if it was deferred until F4. CONCLUSIONS Deferring HCV therapy until advanced liver fibrosis is established could increase liver-related morbidity and mortality in HIV/HCV coinfected individuals, and substantially prolong the time individuals spend with replicating HCV infection.

Endoscopic Biopsy for Intra- and Paraventricular Tumors: Rates of Complications, Mortality, and Tumor Cell Dissemination

Background and Study Aim Intra- and paraventricular tumors are frequently associated with cerebrospinal fluid (CSF) pathway obstruction. Thus the aim of an endoscopic approach is to restore patency of the CSF pathways and to obtain a tumor biopsy. Because endoscopic tumor biopsy may increase tumor cell dissemination, this study sought to evaluate this risk. Patients, Materials, and Methods Forty-four patients who underwent endoscopic biopsies for ventricular or paraventricular tumors between 1993 and 2011 were included in the study. Charts and images were reviewed retrospectively to evaluate rates of adverse events, mortality, and tumor cell dissemination. Adverse events, mortality, and tumor cell dissemination were evaluated. Results Postoperative clinical condition improved in 63.0% of patients, remained stable in 30.4%, and worsened in 6.6%. One patient (2.2%) had a postoperative thalamic stroke leading to hemiparesis and hemineglect. No procedure-related deaths occurred. Postoperative tumor cell dissemination was observed in 14.3% of patients available for follow-up. Conclusions For patients presenting with occlusive hydrocephalus due to tumors in or adjacent to the ventricular system, endoscopic CSF diversion is the procedure of first choice. Tumor biopsy in the current study did not affect safety or efficacy.

[Future cardiac pacemakers – technical visions].

Cardiac pacemakers are routinely used for the treatment of bradyarrhythmias. Contemporary pacemakers are reliable and allow for a patient specific programming. However, pacemaker replacements due to battery depletion are common (~25 % of all implantation procedures) and bear the risk of complications. Batteryless pacemakers may allow overcoming this limitation. To power a batteryless pacemaker, a mechanism for intracorporeal energy harvesting is required. Such a generator may consist out of subcutaneously implanted solar cells, transforming the small amount of transcutaneously available light into electrical energy. Alternatively, intravascular turbines may harvest energy from the blood flow. Energy may also be harvested from the ventricular wall motion by a dedicated mechanical clockwork converting motion into electrical energy. All these approaches have successfully been tested in vivo. Pacemaker leads constitute another Achilles heel of contemporary pacemakers. Thus, leadless devices are desired. Miniaturized pacemaker circuits and suitable energy harvesting mechanisms (incorporated in a single device) may allow catheter-based implantation of the pacemaker in the heart. Such miniaturized battery- and leadless pacemakers would combine the advantages of both approaches and overcome major limitations of today’s systems.

Barriers and facilitators to nurses' acceptance of and implications for injury rates of an IV catheter safety device

This study has the purpose of determining the barriers and facilitators to nurses' acceptance of the Johnson and Johnson Protectiv®* Plus IV catheter safety needle device and implications for needlestick injuries at St. Luke's Episcopal Hospital, Houston, Texas. A one-time cross-sectional survey of 620 responding nurses was conducted by this researcher during December, 2000. The study objectives were to: (1) describe the perceived (a) organizational and individual barriers and facilitators and (b) acceptance of implementation of the IV catheter device; (2) examine the relative importance of these predictors; (3) describe (a) perceived changes in needlestick injuries after implementation of the device; (b) the reported incidence of injuries; and (c) the extent of underreporting by nurses; and (4) examine the relative importance of (a) the preceding predictors and (b) acceptance of the device in predicting perceived changes in needlestick injuries. Safety climate and training were evaluated as organizational factors. Individual factors evaluated were experience with the device, including time using it and frequency of use, and background information, including nursing unit, and length of time as a nurse in this hospital and in total nursing career. The conceptual framework was based upon the safety climate model. Descriptive statistics and multiple and logistic regression were utilized to address the study objectives. ^ The findings showed widespread acceptance of the device and a strong perception that it reduced the number of needlesticks. Acceptance was notably predicted by adequate training, appropriate time between training and device use, solid safety climate, and short length of service, in that order. A barrier to acceptance was nurses' longtime of use of previous needle technologies. Over four-fifths of nurses were compliant in always using the device. Compliance had two facilitators: length of time using device and, to a lesser extent, safety climate. Rates of compliance tended to be lower among nurses in units in which the device was frequently used. ^ High quality training and an atmosphere of caring about nurse safety stand out as primary facilitators that other institutions would need to adopt in order to achieve maximum success in implementing safety programs involving utilization of new safety devices. ^

Prevalence of HIV risk-related behaviors among undocumented Central American immigrant women in Houston, Texas, 2010

The primary aim of this dissertation research is to provide epidemiological data on HIV risk-related behaviors among undocumented Central American immigrant women living in Houston, Texas. Between February and May 2010, we used respondent driven sampling (RDS) to recruit 230 Guatemalan, Honduran, and El Salvadoran women, ages 18 to 50 years, living in Houston without a valid United States visa or residency papers. RDS is a probability-based sampling method that utilizes social networks to access members of hidden populations that lack a sampling frame. Participants completed an interview regarding their demographics, access to and utilization of healthcare services, HIV testing, and sexual behaviors. Data from this study were used 1) to describe the prevalence of sexual HIV risk-related behaviors among undocumented Central American immigrant women, comparing those who recently immigrated to the U.S. (within the past five years) to those with more established residency (of over five years); 2) to describe the prevalence of lifetime HIV testing and evaluate its associated factors in this target population; and 3) to describe the effectiveness of RDS to access members of this target population. ^ As described in Paper 1, there was a generally low prevalence of individual HIV risk-related behaviors (i.e., multiple, concurrent, convenience, and casual sexual partnerships) among the undocumented Central American immigrant women in this study. However, there was evidence of HIV risk due to unprotected sex with male partners who have concurrent sexual partnerships. We identified recent immigrants as the subpopulation at greatest risk, as they were significantly more likely than established immigrants to have multiple and/or concurrent sexual partners. As described in Paper 2, the lifetime prevalence of HIV testing was almost 70%. After adjusting for age, number of years living in the U.S., income security, and resource barriers, lifetime HIV testing was significantly associated with being from Honduras, having more than a sixth grade education, having a regular healthcare provider, and having knowledge of available healthcare resources. Finally, as described in Paper 3, RDS was an effective method for obtaining a diverse sample of Central American immigrant women in Houston. ^ This project is the first to use RDS to conduct an HIV behavioral survey among undocumented Central American immigrant women. Our results will inform the design of future research studies and the implementation of HIV prevention activities among undocumented Central American immigrants in the U.S.^

Bacteremia and mortality within 30 days of catheter-associated bacteriuria

Background: The distinction between catheter-associated asymptomatic bacteriuria (CAABU) and catheter-associated urinary tract infection (CAUTI) has only recently been widely appreciated. Our aims were to describe the relationship between CAUTI/CAABU and subsequent bacteremia and to investigate whether CAUTI/CAABU and antimicrobial use was associated with either bacteremia or mortality within 30 days. ^ Methods: Our study design was retrospective cohort. Patients with a urinary catheter and a positive urine culture between October 2010 and June 2011 at a large tertiary care facility were included. A multivariable model for analysis was constructed which controlled for age, race, Charlson co-morbidity score, catheter type and duration, category of organism,antimicrobials and classification of the catheter-associated bacteriuria as CAUTI or CAABU. ^ Results: Data from 444 catheter associated urine culture episodes in 308 unique patients were included in the analysis. Overall mortality was 21.1% (61 of 308 patients) within 30 days. Among the 444 urine culture episodes, 402 (90.5%) of these episodes were associated with antibiotic use. 52 (11.7%) of episodes were associated with bacteremia, but only 3 episodes of bacteremia (0.7% of 444 CAB episodes) were caused by an organism from the urinary tract. One of these episodes was CAABU and the other 2 were CAUTI. Bacteremia within 30 days was associated with having CAUTI rather than CAABU and having an indwelling urinary catheter rather than a condom catheter. The variables which were found to be significant for mortality within 30 days were a higher Charlson co-morbidity score and the presence of Candida in the urine culture. Use of antimicrobial agents to treat the bacteriuria was not associated with an increase or decrease in either bacteremia or mortality. ^ Conclusions: Our findings call into question the practice of giving antimicrobial agents to treat bacteriuria in an inpatient population with nearly universal antimicrobial use. A better practice may be targeted treatment of bacteriuria in patients with risk factors predictive of bacteremia and mortality.^

Nitric oxide-related species inhibit evoked neurotransmission but enhance spontaneous miniature synaptic currents in central neuronal cultures

Nitric oxide (NO·) does not react significantly with thiol groups under physiological conditions, whereas a variety of endogenous NO donor molecules facilitate rapid transfer to thiol of nitrosonium ion (NO+, with one less electron than NO·). Here, nitrosonium donors are shown to decrease the efficacy of evoked neurotransmission while increasing the frequency of spontaneous miniature excitatory postsynaptic currents (mEPSCs). In contrast, pure NO· donors have little effect (displaying at most only a slight increase) on the amplitude of evoked EPSCs and frequency of spontaneous mEPSCs in our preparations. These findings may help explain heretofore paradoxical observations that the NO moiety can either increase, decrease, or have no net effect on synaptic activity in various preparations.

A case of central nervous system vasculitis related to an episode of Guillain-Barrè syndrome

The authors report their knowledge about an uncommon case of isolated vasculitis, restricted to the left sylvian artery during an auto-immune Guillain-Barrè syndrome (GBS), sustained by cytomegalovirus (CMV). An acute cardiopulmonary failure requiring a ventilator and vasopressor support manifested, notwithstanding plasma exchanging and immune-modulating therapy. An IgM-enriched formula administration coincided with a rapid amelioration of GBS and vasculitis to a complete recovery the next month after her discharge to a rehabilitation centre.

Low density lipoprotein receptor-related protein mediates apolipoprotein E-dependent neurite outgrowth in a central nervous system-derived neuronal cell line.

The epsilon 4 allele of apolipoprotein E (apoE) is a major risk factor for Alzheimer disease, suggesting that apoE may directly influence neurons in the aging brain. Recent data suggest that apoE-containing lipoproteins can influence neurite outgrowth in an isoform-specific fashion. The neuronal mediators of apoE effects have not been clarified. We show here that in a central nervous system-derived neuronal cell line, apoE3 but not apoE4 increases neurite extension. The effect of apoE3 was blocked at low nanomolar concentrations by purified 39-kDa protein that regulates ligand binding to the low density lipoprotein receptor-related protein (LRP). Anti-LRP antibody also completely abolished the neurite-promoting effect of apoE3. Understanding isoform-specific cell biological processes mediated by apoE-LRP interactions in central nervous system neurons may provide insight into Alzheimer disease pathogenesis.

Injetor intravascular de CO2: estudo in vivo de viabilidade inicial do dispositivo e de qualidade de imagem

INTRODUÇÃO: Durante procedimentos endovasculares, estão presentes os riscos relacionados ao uso dos contrastes iodados, tais como a nefropatia por contraste, uma vez que é fundamental o emprego de um meio de contraste para a obtenção das imagens radiológicas vasculares. A injeção intravascular de gás CO2 purificado é reconhecidamente uma alternativa relativamente mais segura ao contraste iodado, contudo, seu manuseio artesanal pode também trazer dificuldades técnicas e riscos aos pacientes. Para contemplar estas questões, foi desenvolvido o protótipo de um injetor intravascular de CO2 medicinal, microprocessado, dedicado à obtenção de imagens angiográficas. OBJETIVOS: Realizar os testes de viabilidade técnica inicial do protótipo em modelo in vivo. MÉTODOS: Realizar a angioplastia da artéria renal esquerda de 10 porcos, divididos em 2 grupos: Grupo 1 (n=5) injeção de contraste iodado, Grupo 2 (n=5) injeção de CO2 através do protótipo. Monitorização clínica e laboratorial dos animais no pré, intra e pós-operatório, com exames de função renal na véspera e 48h após os procedimentos e 3 gasometrias arteriais seriadas no intra-operatório. Observação clínica foi mantida por 48h no pós- operatório. RESULTADOS: Os procedimentos de angioplastia com CO2 foram realizados com sucesso técnico de 100%, sem necessidade de complementação com injeção de contraste iodado no Grupo 2. Não foram identificadas falhas no protótipo em funcionamento. Não foram identificadas alterações clínicas ou radiológicas sugestivas de contaminação por ar ambiente do sistema de CO2 e nem alterações laboratoriais nos animais. As imagens angiográficas obtidas no Grupo 2 foram consideradas, numa avaliação subjetiva, relativamente inferiores às imagens obtidas no Grupo 1. DISCUSSÃO: A qualidade inferior de imagem no Grupo 2 pode ser atribuída ao equipamento de fluoroscopia utilizado, com software desatualizado em relação aos equipamentos atuais, que incluem pré-configurações para angiografia com CO2; no entanto, ainda assim todos os procedimentos propostos no Grupo 2 foram realizados com sucesso técnico, o que nos leva a classificar as imagens deste grupo 2 como satisfatórias. O manuseio do aparelho mostrou-se ágil e eficiente, com a programação dos parâmetros sendo realizada com facilidade através do visor \"touch screen\", comparativamente superior ao método artesanal de injeção de CO2 com seringas em selo d\'água. CONCLUSÕES: O protótipo do aparelho injetor intravascular de CO2 funcionou de forma adequada durante os testes e as imagens obtidas permitiram a compleição com sucesso dos procedimentos. Portanto, os resultados positivos obtidos sugerem que o equipamento é tecnicamente viável

Deformable templates for tracking and analysis of intravascular ultrasound sequences

Deformable Template models are first applied to track the inner wall of coronary arteries in intravascular ultrasound sequences, mainly in the assistance to angioplasty surgery. A circular template is used for initializing an elliptical deformable model to track wall deformation when inflating a balloon placed at the tip of the catheter. We define a new energy function for driving the behavior of the template and we test its robustness both in real and synthetic images. Finally we introduce a framework for learning and recognizing spatio-temporal geometric constraints based on Principal Component Analysis (eigenconstraints).