573 research outputs found

    Bidirectional ventricular tachycardia in cardiac sarcoidosis.

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    A 73-year-old man with history of pulmonary sarcoidosis was found to have runs of non-sustained bidirectional ventricular tachycardia (BVT) with two different QRS morphologies on a Holter monitor. Cardiac magnetic resonance delayed gadolinium imaging revealed a region of patchy mid-myocardial enhancement within the left ventricular basal inferolateral myocardium. An 18-fluorodeoxyglucose positron emission tomography (FDG-PET) showed increased uptake in the same area, consistent with active sarcoid, with no septal involvement. Follow-up FDG-PET one year later showed disease progression with new septal involvement. Cardiac sarcoidosis, characterized by myocardial inflammation and interstitial fibrosis that can lead to conduction system disturbance and macro re-entrant arrhythmias, should be considered in differential diagnosis of BVT. BVT may indicate septal involvement with sarcoidosis before the lesions are large enough to be detected radiologically

    Electrocardiographic Patterns of Ventricular Arrhythmias in Arrhythmogenic Right Ventricular Dysplasia/Cardiomyopathy

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    Ventricular arrhythmias in patients with ARVD/C are common. Differentiation between idiopathic ventricular tachycardia and arrhythmogenic right ventricular dysplasia is of utmost importance. Baseline sinus rhythm electrocardiography as well as electrocardiographic differences during ventricular arrhythmias (VT or PVCs) can be helpful in differentiating the two disease states. The pathological fibrofatty myocyte replacement in ARVD/C as well as ventricular arrhythmia origin are likely responsible for these differences

    Randomized trial of conventional transseptal needle versus radiofrequency energy needle puncture for left atrial access (the TRAVERSE-LA study).

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    BackgroundTransseptal puncture is a critical step in achieving left atrial (LA) access for a variety of cardiac procedures. Although the mechanical Brockenbrough needle has historically been used for this procedure, a needle employing radiofrequency (RF) energy has more recently been approved for clinical use. We sought to investigate the comparative effectiveness of an RF versus conventional needle for transseptal LA access.Methods and resultsIn this prospective, single-blinded, controlled trial, 72 patients were randomized in a 1:1 fashion to an RF versus conventional (BRK-1) transseptal needle. In an intention-to-treat analysis, the primary outcome was time required for transseptal LA access. Secondary outcomes included failure of the assigned needle, visible plastic dilator shavings from needle introduction, and any procedural complication. The median transseptal puncture time was 68% shorter using the RF needle compared with the conventional needle (2.3 minutes [interquartile range {IQR}, 1.7 to 3.8 minutes] versus 7.3 minutes [IQR, 2.7 to 14.1 minutes], P = 0.005). Failure to achieve transseptal LA access with the assigned needle was less common using the RF versus conventional needle (0/36 [0%] versus 10/36 [27.8%], P < 0.001). Plastic shavings were grossly visible after needle advancement through the dilator and sheath in 0 (0%) RF needle cases and 12 (33.3%) conventional needle cases (P < 0.001). There were no differences in procedural complications (1/36 [2.8%] versus 1/36 [2.8%]).ConclusionsUse of an RF needle resulted in shorter time to transseptal LA access, less failure in achieving transseptal LA access, and fewer visible plastic shavings

    Decentralized motion planning for multiple mobile robots: The cocktail party model

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    Abstract. This paper presents an approach for decentralized real-time motion planning for multiple mobile robots operating in a common 2-dimensional environment with unknown stationary obstacles. In our model, a robot can see (sense) the surrounding objects. It knows its current and its target’s position, is able to distinguish a robot from an obstacle, and can assess the instantaneous motion of another robot. Other than this, a robot has no knowledge about the scene or of the paths and objectives of other robots. There is no mutual communication among the robots; no constraints are imposed on the paths or shapes of robots and obstacles. Each robot plans its path toward its target dynamically, based on its current position and the sensory feedback; only the translation component is considered for the planning purposes. With this model, it is clear that no provable motion planning strategy can be designed (a simple example with a dead-lock is discussed); this naturally points to heuristic algorithms. The suggested strategy is based on maze-searching techniques. Computer simulation results are provided that demonstrate good performance and a remarkable robustness of the algorithm (meaning by this a virtual impossibility to create a dead-lock in a “random ” scene). Keywords: mobile robots, autonomous agents, decentralized intelligence, robot motion plannin

    Expression of LMP1 in epithelial cells leads to the activation of a select subset of NF-kappa B/Rel family proteins.

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    This study demonstrates that the Epstein-Barr virus protein LMP1 activates a specific subset of NF-kappa B/Rel proteins in the C33 epithelial cell line. Western immunoblot analysis used to analyze the intracellular distribution and abundance of the proteins present in these complexes demonstrated that levels of the p50 and p52 proteins were significantly elevated in the nuclei of LMP1-expressing cells. The data also suggest that LMP1 facilitates the translocation of p50 to the nucleus and may affect the processing of the p100 and p105 precursor proteins or the stability of p52 and p50

    I kappa B interacts with the nuclear localization sequences of the subunits of NF-kappa B: a mechanism for cytoplasmic retention.

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    NF-kappa B is an inducible transcription factor comprised of a 50-kD (p50) and a 65-kD (p65) subunit. Induction of NF-kappa B activity, which is a critical event in many signal transduction pathways, involves release from a cytoplasmic inhibitory protein, I kappa B, followed by translocation of the active transcription factor complex into the nucleus. Earlier studies suggested that I kappa B targets the p65 subunit of NF-kappa B. However, we demonstrate by in vitro and in vivo methods that the recently cloned I kappa B/MAD-3 interacts with both the p50 and p65 subunits of NF-kappa B, as well as c-Rel. Furthermore, an alternatively spliced, dimerization-deficient transforming variant of p65 (p65 delta) interacts extremely weakly with I kappa B/MAD-3, suggesting that dimerization is important for interaction. We demonstrate that the conserved nuclear localization sequences (NLSs) of NF-kappa B and c-Rel are the targets for I kappa B/MAD-3 interaction. Indirect immunofluorescence experiments demonstrate that I kappa B/MAD-3 expression retains both p65 and p50 in the cytoplasm. Furthermore, and most important, a p65 that contains an SV40 large T antigen NLS in addition to its own NLS is no longer retained in the cytoplasm in the presence of I kappa B/MAD-3. We propose that I kappa B/MAD-3 masks the NLSs of NF-kappa B and c-Rel and that this constitutes the mechanism for cytoplasmic retention of these proteins

    The echo-transponder electrode catheter: A new method for mapping the left ventricle

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    AbstractThe ability to locate catheter position in the left ventricle with respect to endocardial landmarks might enhance the accuracy of ventricular tachycardia mapping. An echotransponder system (Telectronics, Inc.) was compared with biplane fluoroscopy for left ventricular endocardial mapping. A 6F electrode catheter was modified with the addition of a piezoelectric crystal 5 mm from the tip. This crystal was connected to a transponder that received and transmitted ultrasound, resulting in a discrete artifact on the two-dimensional echocardiographic image corresponding to the position of the catheter tip.Catheters were introduced percutaneously into the left ventricle of nine anesthetized dogs. Two-dimensional echotransponder and biplane fluoroscopic images were recorded on videotape with the catheter at multiple endocardial sites. Catheter location was marked by delivering radiofrequency current to the distal electrode, creating a small endocardial lesion. Catheter location by echo-transponder and by fluoroscopy were compared with lesion location without knowledge of other data. Location by echo-transponder was 8.7 ± 5.1 mm from the center of the radiofrequency lesion versus 14 + 7.8 mm by fluoroscopy (n = 15, p = 0.023). Echo-transponder localization is more precise than is biplane fluoroscopy and may enhance the accuracy of left ventricular eledrophysiologic mapping
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