Suppression of Intra‐atrial Reentrant Tachycardia in Patients with Atrial Overdrive Pacing

Background. Intra‐atrial reentrant tachycardia (IART) is a common arrhythmia in adult patients with palliated congenital heart disease (CHD). Traditional treatment methods such as antiarrhythmic drugs (AADs) or radiofrequency ablation are often unsuccessful or cause side effects. These patients often require frequent cardioversion and anticoagulation. The purpose of this study is to evaluate the success of overdrive atrial pacing for the suppression of IART in CHD. Methods. Single center, investigational review board approved, retrospective review of nine patients with CHD and documented, recurrent IART. Patients served as their own historical controls for this study. Phase I was defined as the period 2 years prior to atrial pacing intervention, and Phase II was defined as ≥13 months with atrial pacing; enabled or implanted rate responsive or dynamic overdrive A pacing. During Phase II, the patients' rhythm was monitored by either symptom reporting, ECG, Holter monitoring or pacer diagnostics every 2 months. Results. Cardioversion post A pacing decreased: from 25 to 3, P < .003, patients requiring cardioversions 9 to 1, P < .001, no. AADs 18 to 7, P < .02. Conclusions. Overdrive atrial pacing, ≥70 ppm, is a viable treatment option to suppress recurrent IART. With the suppression of IART, the need for cardioversion, and AAD can be significantly reduced.     

Teaching ultrasound-guided peripheral venous catheter placement through immersive virtual reality: An explorative pilot study

Introduction:Immersive virtual reality (IVR)-based training is gaining ground as an educational tool in healthcare. When combined with well-established educational methods, IVR can potentially increase competency and autonomy in ultrasound (US)-guided peripheral venous cannulation.The aim of this study was to examine the impact of adding IVR training to a course in US-guided peripheral venous cannulation.Methods:Medical students (n = 19) from the University of Southern Denmark with no former standardized US education were recruited to voluntarily participate in a pilot study, designed as a randomized controlled trial. The primary outcome was the proportion of successful peripheral venous cannulations on a phantom. Secondary outcomes included the proportion of surface punctures on the phantom and procedure time. Participants received e-learning on the basic US before randomization to either IVR (n = 10) or no further training (n = 9). The additional IVR training comprised 10 virtual scenarios for US-guided peripheral venous catheter (PVC) placement. Students were subsequently evaluated in peripheral venous cannulation by a blinded assessor.Results:The proportion of successful peripheral venous cannulations was significantly higher in the IVR group (P ≤ .001). The proportions of successful cannulations were significantly higher in the IVR group compared to the control group for the 1st and 2nd PVC (P = .011, P = .023), but not for the 3rd PVC (P = .087). Similar results were found for the proportion of surface punctures (1st: P ≤ .001, 2nd: P = .001, and 3rd: P = .114). No significant differences in procedure times were found between the groups.Conclusion:This pilot study showed that adding an IVR-based training simulation to an existing e-learning curriculum significantly increased the learning efficacy of US-guided PVC placement for medical students.     

An in vitro expansion score for tissue‐engineering applications with human bone marrow‐derived mesenchymal stem cells

Human bone marrow‐derived mesenchymal stem cells (MSCs) have limited growth potential in vitro and cease to divide due to replicative senescence, which from a tissue‐engineering perspective has practical implications, such as defining the correct starting points for differentiation and transplantation. Time spent in culture before the loss of required differentiation potential is different and reflects patient variability, which is a problem for cell expansion. This study aimed to develop a score set which can be used to quantify the senescent state of MSCs and predict whether cells preserve their ability to differentiate to osteogenic, adipogenic and chondrogenic phenotypes, based on colony‐forming unit (CFU) assay, population doubling time (PDT), senescence‐associated β‐galactosidase (SA‐β‐Gal) activity, cell size, telomere length and gene expression of MSCs cultured in vitro over 11 passages. This set of morphological, physiological and genetic senescence markers was correlated to the ability of MSCs to differentiate. Differentiation efficiency was assessed by marker genes and protein expression. CFUs decreased with increasing passage number, whereas SA‐β‐Gal activity and PDT increased; however, the correlation with MSCs' differentiation potential was sometimes unexpected. The expression of genes related to senescence was higher in late‐passage cells than in early‐passage cells. Early‐passage cells underwent efficient osteogenic differentiation, with mid‐passage cells performing best in chondrogenic differentiation. Late‐passage cells preserve only adipogenic differentiation potential. Based on this marker set, we propose a senescence score in which combined markers give a reliable quality control of MSCs, not depending only on mechanistic passage number. Copyright © 2013 John Wiley & Sons, Ltd.     

Association of GST M1 null polymorphism with Parkinson's disease in a Chilean population with a strong Amerindian genetic component

We have studied the association of a null mutation of Glutathione Transferase M1 (GST M1*0/0) with Parkinson's disease (MIM 168600) in a Chilean population with a strong Amerindian genetic component. We determined the genotype in 349 patients with idiopathic Parkinson's disease (174 female and 175 male; 66.84+/-10.7 years of age), and compared that to 611 controls (457 female and 254 male; 62+/-13.4 years of age). A significant association of the null mutation in GST M1 with Parkinson's disease was found (p=0.021), and the association was strongest in the earlier age range. An association of GSTM1*0/0 with Parkinson's disease supports the hypothesis that Glutathione Transferase M1 plays a role in protecting astrocytes against toxic dopamine oxidative metabolism, and most likely by preventing toxic one-electron reduction of aminochrome.     

A new pulse sequence for determining T1 and T2 simultaneously

Determination of the relaxation times T1 and T2 which are important for tissue characterization generally requires the use of different pulse sequences in magnetic resonance imaging. In this study, a new pulse sequence which facilitates simultaneous determination of the T1 and T2 times is presented. Determination takes place in this case pixel by pixel from the measured images. The measuring time corresponds in this case approximately to that of a normal spin-echo sequence with long repetition time and two data acquisitions. The functional dependence of the accuracy of the T1 and T2 determination upon external errors, e.g., angle of rotation errors, is discussed. The tissue contrast behavior of the individual echoes is shown and its dependence on pulse parameters is explained.