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A 45-year-old man with nonischemic cardiomyopathy and end-stage renal disease had lived uneventfully with a cardiac resynchronization therapy defibrillator (CRT-D) for 5 years. Less than a month before presenting at our institution, he had undergone stenting of his partially occluded subclavian vein, to relieve stenosis of the ipsilateral arteriovenous fistula that was used for his hemodialysis. The CRT-D subsequently discharged. Device interrogation revealed that electrical noise originating from leads damaged by the stent had caused the inappropriate shock and intermittent electrical discharges thereafter. The patient was highly traumatized by these events and insisted upon device removal, which deprived him of a potentially life-saving intervention. He later had a cardiac arrest that resulted in sustained profound hypoxic ischemic encephalopathy with minimal neurologic recovery: his family placed him in a long-term care facility on ventilator support, with a tracheostomy and feeding tube. This situation might have been avoided through collaboration between the interventional radiologist and the electrophysiologist. To our knowledge, this is the first report of a patient with nonischemic cardiomyopathy and end-stage renal disease who presented with inappropriate defibrillator discharge caused by lead damage secondary to stenting across the leads.

Introduction: Radiofrequency Catheter ablation (RFCA) has become an established strategy to treat symptomatic and drug refractory cases of Atrial Fibrillation (AF). Despite its safety, RFCA accompanies some serious complications such as esophageal thermal damage, that makes physicians more cautious while ablating the posterior structures and avoid using higher powers for RFCA. Hypothesis: We aim to investigate the safety of 50 watts RFCA compared with 35 watts, by the novel method of detecting any esophageal enhancement with Late Gadolinium Enhancement MRI (LGE-MRI). Methods: Records of 511 AF patients from 2012 to 2016 were collected; who underwent RFCA and had LGE-MRI post-ablation to detect any esophageal injury. The method of ablation for both groups includes Pulmonary Vein Isolation (PVI) and Posterior Wall Debulking (PWD). Patients were categorized into 2 groups: The High Power (HP) group who underwent ablation with 50 Watts catheters and the Low Power (LP) group, for whom the 35 Watts catheters were used. With regard to their respective esophageal enhancement, patients were classified as those who had no, mild, moderate, or significant esophageal enhancement. Results: There were 459 patients in HP group (301 men; mean age 70.4 ± 11.2) and 52 patients in LP group (32 male; mean age 64.1 ± 11.7). HP group was significantly older (p < 0.05) and persistent type of AF was more common among them (51.5% vs 25%, p < 0.05). The incidence of esophageal enhancement post-ablation was not significantly different among HP and LP groups (Figure 1) but the procedure time was significantly shorter for HP group (149.3 ± 64.8 minutes vs 308.4 ± 104, p < 0.001). None of our patients (in both groups) developed serious complications such as atrioesophageal fistula. Conclusions: Using high power radiofrequency catheter ablation for AF patients shows no correlation with esophageal enhancement post-PWD ablation, furthermore they can significantly reduce the procedure time.

Introduction: Paroxysmal supraventricular tachycardias (PSVT) are among common cardiac arrhythmias. Atrial fibrosis correlates with several cardiac dysrhythmias and while its role is well described in atrial fibrillation, its role in PSVTs is less clear. We sought to investigate the extent of left atrial (LA) and right atrial (RA) enhancement in patients with supraventricular tachycardia (SVT) without a history of atrial fibrillation. Methods and Results: In our case-control study the information of 212 patients was collected. 30 patients with PSVT (age 48.6 ± 20.1 and 43% male) and 182 patients with no known arrhythmic disorder as the control group (age 50.3 ± 14.7 and 66% males) matched for age, LA volume, left ventricular ejection fraction (LVEF) and other comorbidities such as hypertension, hyperlipidemia, diabetes, coronary artery disease, heart failure, and smoking. LA and RA fibrosis were quantified by the Late Gadolinium Enhanced Magnetic Resonance Imaging (LGE-MRI) using signal intensity analysis. The average % LA wall enhancements were 15.2% ± 6.3% in the SVT group and 10.7% ± 6.5% in the control group (p = 0.001) while for RA enhancement they were 11.1% ± 5% and 8.1% ± 4.1% for the SVT and control groups respectively (p = 0.009). Our logistic regression analysis showed that for each 1% increase in LA and RA enhancement, there was a 19% and 16% greater chance of having PSVT (p = 0.006, p = 0.013 respectively). Conclusions: Our study suggests that the extent of atrial fibrosis (either in the left or right atrium), quantified using LGE-MRI, is higher among patients with PSVT. The impact of increased atrial fibrosis in this patient population, could be correlated with other major adverse cardiac events.

Introduction: Left Atrial (LA) Fibrosis may serve as a substrate for Atrial Fibrillation (AF) and the total percentage of LA fibrosis affects the outcome of ablation therapy. But the role of “thick” (transmural or near transmural) fibrotic tissue, as opposed to superficial fibrosis, in the AF prognosis is not well studied. We assess the amount of LA wall fibrosis thickness on AF ablation outcome. Methods and Results: Patients’ parameters were obtained from DECAAF trial. LA fibrosis was quantified with Late Gadolinium Enhancement MRI (LGE-MRI) and when within LA myocardium, 3 or more voxels (each voxel = 0.625mm) were enhanced that area was considered as thick fibrotic tissue. First Cox regression was devised to measure the impact of thick fibrosis on the outcome of AF ablation. Then patients were divided into 2 groups: First group with more than 3.89% of thick LA fibrosis and the second group with less than that. This cut-off was achieved through Receiver Operation Curve analysis of our cohort. Patients were 58.9 ± 10.9 of age and their amount of thick LA fibrosis was 3.5% ± 2.4%. The result of Cox regression showed: 1% increase in the extent of thick LA fibrosis, the recurrence rate of AF increases by 20% after ablation. (HR = 1.2, CI 95% = 1.1 - 1.3, P < 0.0001). The first and second group matched in terms of age, gender, LA volume, and co-morbidities. The first group were 2.9 times more at risk for AF recurrence after the ablation (CI95% = 1.9 - 4.5, P < 0.001) and they had a significantly lower chance of remaining AF free after ablation (0.385 vs 0.621, P < 0.0001) Conclusions: We found the percentage of LA wall fibrosis thickness to correlate with a worse AF ablation outcome and an increased risk of AF recurrence. Therefore assessing percentage of thick fibrotic tissue within LA wall may be of a greater interest than assessing total percentage of fibrosis.

Introduction: Mitral Valve Disease (MVD) is associated with atrial fibrillation (AF) and can worsen its prognosis. Left Atrial (LA) fibrosis is a known substrate for AF and its extent affects the management. Hypothesis: We hypothesize MVD increases LA fibrosis in AF patients and the chance of AF ablation failure. Secondly, even in patients with low levels of LA fibrosis that are optimal candidates for ablation, presence of MVD still worsens the outcome. Methods: Patients were categorized in two groups: 140 patients had coexisting MVD and AF, and 100 patients AF without MVD. MVD was defined as any dysfunctionality of mitral valve including mitral stenosis, mitral regurgitation, and history of previous mitral valve surgery . LA fibrosis was quantified by Late Gadolinium Enhancement MRI (LGE-MRI). Baseline characteristics were gathered through chart reviewing. Following ablation, patients were followed for median of 71 months for AF recurrence. Results: Patients were 76.4 ± 10.7 years of age in MVD+AF group and 64.2 ± 14.7 in AF group (p < 0.0001). Extent of LA fibrosis was 18.1% ± 9.3 and 10.3% ± 5.3 in MVD+AF and AF group, respectively (p < 0.0001). The result of our statistical model adjusted for possible cofounders showed that coexistence of MVD in AF patients result in presence of 6.4% more LA fibrosis (p < 0.00001) and lowered the chance of remaining AF free after the ablation (recurrence-free ratio of 0.554 vs 0.757 in MVD+AF and AF group respectively, P < 0.05) (Figure 1). In patients with LA fibrosis less than 20% who would be ideal AF ablation candidate, the presence of MVD decreased the chance to remain AF free (0.574 vs 0.775 in MVD+AF and AF respectively, p < 0.05) (Figure 2). Conclusions: MVD increases LA fibrosis in AF patients and the chance of AF recurrence post-ablation.

Plasma trimethylamine-N-oxide (TMAO) is associated with cardiovascular disease; however specific relationships with cardiac arrhythmias are unknown. We evaluated the association between plasma TMAO and incident atrial fibrillation (AF).Risk associations were explored among 3797 patients with suspected stable angina in the Western Norway Coronary Angiography Cohort (WECAC) and verified in 3143 elderly participants in the community-based Hordaland Health Study (HUSK). Information on endpoints was obtained from nationwide registries.Median follow-up was 7.3 and 10.8 years in the WECAC and HUSK cohorts, respectively, and 412 (10.9%) and 484 (15.4%) subjects were registered with incident AF. The age and gender adjusted HRs were 1.16, 95% CI 1.05-1.28 and 1.10, 95% CI 1.004-1.19 per 1 SD increase in log-transformed plasma TMAO. Adjusting for hypertension, BMI, smoking, diabetes, or intake of total choline, a TMAO precursor, did not materially influence the risk associations. Among patients in WECAC, further extensive adjustment for other AF risk factors yielded similar results. Adding TMAO to traditional AF risk factors (age, gender, hypertension, BMI, smoking and diabetes) yielded a continuous net reclassification improvement of 0.108, 95% CI 0.015-0.202 and 0.139, 95% CI 0.042-0.235.Plasma TMAO was associated with and improved reclassification of incident AF in two independent Norwegian cohorts with long-term follow-up. The relationship was independent of traditional AF risk factors, as well as of dietary choline intake. Our findings motivate further studies to explore endogenous metabolic factors influencing the relationship between TMAO and cardiovascular disease.

The study sought to determine the effect of persistent atrial fibrillation (AF) on device-measured activity and mortality.Patients with AF often complain of fatigue, which may be reflected in patient activity. Daily activity can be objectively measured by implanted devices.We retrospectively studied patients (n = 266, 88% male, 69 ± 10 years of age) from the deidentified Medtronic CareLink database with persistent AF (≥28 consecutive days with ≥23 h of AF/day), dual-chamber implantable cardioverter-defibrillators (ICDs) capable of monitoring daily activity and AF burden, no AF between months 1 and 6 post-implant, and ≥1 year of data.The first persistent AF episode occurred 980 ± 534 days after implant and lasted a median of 87 days (interquartile range: 49 to 161 days). Average daily activity over a week just prior (baseline) to the first persistent AF episode was compared to each of the 4 weeks during the AF episode and to each of the weeks following termination of the persistent AF episode. Daily activity decreased significantly from the baseline week (135 min/day) compared to each of the 4 consecutive weeks after AF onset (8%, 11%, 14%, and 17% decrease, p 0.001). Mortality at 4 years was increased in patients with persistent AF compared to a matched group with no persistent AF (20.6% vs. 8.6%, p 0.01).Patients with ICDs have a significant reduction in activity following the onset of persistent AF and a significant increase in mortality when compared to a matched group without persistent AF. Objective measures of activity may more accurately reflect the impact of persistent AF on patients' functional status.

The end-stage renal disease population poses a challenge for obtaining venous access required for life-saving invasive cardiac procedures. In this case report, we describe an adult patient with end-stage renal disease in whom the hepatic vein was the only available access to implant a single-lead permanent cardiac pacemaker. A 63-year-old male with end-stage renal disease on maintenance hemodialysis and permanent atrial fibrillation/atrial flutter presented with symptomatic bradycardia. Imaging studies revealed all traditional central venous access sites to be occluded/non-accessible. With the assistance of vascular interventional radiology, a trans-hepatic venous catheter was placed. This was then used to place a right ventricular pacing lead with close attention to numerous technical aspects. The procedure was completed successfully with placement of a single-lead permanent cardiac pacemaker.

The volatile fluorofullerene products of high-temperature reactions of C60 with the ternary manganese(III, IV) fluorides KMnF4, KMnF5, A2MnF6 (A+ = Li+, K+, Cs+), and K3MnF6 were monitored as a function of reaction temperature, reaction time, and stoichiometric ratio by in situ Knudsen-cell mass spectrometry. When combined with fluorofullerene product ratios from larger-scale (bulk) screening reactions with the same reagents, an optimized set of conditions was found that yielded the greatest amount of C60F8 (KMnF4/C60 mol ratio 28–30, 470 °C, 4–5 h). Two isomers of C60F8 were purified by HPLC, one of which has not been previously reported. Quantum chemical calculations at the DFT level combined with 1D and 2D 19F NMR, FTIR, and FT-Raman spectroscopy indicate that the C60F8 isomer previously reported to be 1,2,3,8,9,12,15,16-C60F8 is actually 1,2,3,6,9,12,15,18-C60F8, making it the first high-temperature fluorofullerene with non-contiguous fluorine atoms. The new isomer, which was found to be 1,2,7,8,9,12,13,14-C60F8, is predicted to be 5.5 kJ mol−1 more stable than 1,2,3,6,9,12,15,18-C60F8 at the DFT level. In addition, new DFT calculations and spectroscopic data indicate that the compound previously isolated from the high-temperature reaction of C60 and K2PtF6 and reported to be 16-CF3-1,2,3,8,9,12,15-C60F7 is actually 18-CF3-1,2,3,6,8,12,15-C60F7.

Mutations in the cardiac ryanodine receptor 2 (RyR2) have been associated with catecholaminergic polymorphic ventricular tachycardia and a form of arrhythmogenic right ventricular dysplasia. To study the relationship between RyR2 function and these phenotypes, we developed knockin mice with the human disease-associated RyR2 mutation R176Q. Histologic analysis of hearts from RyR2 R176Q /+ mice revealed no evidence of fibrofatty infiltration or structural abnormalities characteristic of arrhythmogenic right ventricular dysplasia, but right ventricular end-diastolic volume was decreased in RyR2 R176Q /+ mice compared with controls, indicating subtle functional impairment due to the presence of a single mutant allele. Ventricular tachycardia (VT) was observed after caffeine and epinephrine injection in RyR2 R176Q /+ , but not in WT, mice. Intracardiac electrophysiology studies with programmed stimulation also elicited VT in RyR2 R176Q /+ mice. Isoproterenol administration during programmed stimulation increased both the number and duration of VT episodes in RyR2 R176Q /+ mice, but not in controls. Isolated cardiomyocytes from RyR2 R176Q /+ mice exhibited a higher incidence of spontaneous Ca 2+ oscillations in the absence and presence of isoproterenol compared with controls. Our results suggest that the R176Q mutation in RyR2 predisposes the heart to catecholamine-induced oscillatory calcium-release events that trigger a calcium-dependent ventricular arrhythmia.

Ryanodine receptors (RyRs) are the major sarcoplasmic reticulum calcium-release channels required for excitation-contraction coupling in skeletal and cardiac muscle. Mutations in RyRs have been linked to several human diseases. Mutations in the cardiac isoform of RyR2 are associated with catecholaminergic polymorphic ventricular arrhythmias (CPVT), and arrhythmogenic right ventricular dysplasia type 2 (ARVD2), whereas mutations in the skeletal muscle isoform (RyR1) are linked to malignant hyperthermia (MH) and central core disease (CCD). RyRs are modulated by several other proteins, including the FK506 binding proteins (FKBPs), FKBP12 and FKBP12.6. These immunophilins appear to stabilize a closed state of the channel and are important for cooperative interactions among the subunits of RyRs. This review discusses the regulation of RyRs by FKBPs and the possibility that defective modulation of RyR2 by FKBP12.6 could play a role in heart failure, CPVT, and ARVD2. Also discussed are the consequences of FKBP12 depletion to skeletal muscle and the possibility of FKBP12 involvement in certain forms of MH or CCD.

Background: Atrioesophageal fistula is a well-recognized complication of catheter ablation of atrial fibrillation (AF) with a reported incidence of 0.015-0.2%. Careful screening with Magnetic resonance imaging (MRI) and Esophagogastroduodenosopy (EGD) may help avoid this potentially lethal

The method for separation of emission (EM) and excitation (EX) spectra of a protein into EM and EX spectra of its tyrosine (Tyr) and tryptophan (Trp) residues was described. The method was applied to analysis of Escherichia coli RecA protein and its complexes with Mg(2+), ATPgammaS or ADP, and single-stranded DNA (ssDNA). RecA consists of a C-terminal domain containing two Trp and two Tyr residues, a major domain with five Tyr residues, and an N-terminal domain without these residues (R. M. Story, I. T. Weber, and T. A. Steitz (1992) Nature (London) 355, 374-376). Because the fluorescence of Tyr residues in the C-terminal domain was shown to be quenched by energy transfer to Trp residues, Trp and Tyr fluorescence of RecA was provided by the C-terminal and the major domains, respectively. Spectral analysis of Trp and Tyr constituents revealed that a relative spatial location of the C-terminal and the major domains in RecA monomers was different for their complexes with either ATPgammaS or ADP, whereas this location did not change upon additional interaction of these complexes with ssDNA. Homogeneous (that is, independent of EX wavelength) and nonhomogeneous (dependent on EX wavelength) types of Tyr and Trp fluorescence quenching were analyzed for RecA and its complexes with nucleotide cofactors and ssDNA. The former was expected to result from singlet-singlet energy transfer from these residues to adenine of ATPgammaS or ADP. By analogy, the latter was suggested to proceed through energy transfer from high vibrational levels of the excited state of Trp and Tyr residues to the adenine. In this case, for correct calculation of the overlap integral, Trp and Tyr donor emission spectra were substituted by the spectral function of convolution of emission and excitation spectra that resulted in a significant increase of the overlap integral and gave an explanation of the nonhomogeneous quenching of Trp residues in the C-terminal domain.

PET/0.6 PHB melt, where PET is poly(ethylene terephthalate), PHB is p-hydroxybenzoic acid and 0.6 is the mole fraction of the second (liquid crystal, LC) component in the copolymer, was subjected to constant magnetic fields at several temperatures in the range 240–315°C, cooled to 25°C, and then studied by x-ray diffractometry, electron diffractometry, scanning electron microscopy (SEM), dilatometry (TMA) and thermogravimetry (TGA). Given the anisotropy of the magnetic susceptibility, significant orientation effects are found. The extent of orientation was evaluated as a function of the magnetic field strength, time of the field imposition and temperature; cyclic fields were also applied. Large changes in the extent of material orientation are connected to the phase transitions determined before [9] . The LC-rich islands [4] cause channeling of flexible sequences between the LC sequences, as predicted from an extension [20] of the statistical–mechanical theory of Flory [21] . In the phase region of coexistence of the smectic E, smectic B and isotropic phases there is a growth of the size of the islands—a consequence of increased mobility. However, in the next higher temperature region, where the smectic E phase is no longer present, one observes gradual dissolution of the islands along with the temperature increase. These conclusions are derived from both x-ray diffractometry and SEM. The phase transition temperatures from TMA agree with those found by other techniques. Linear expansivity is negative along the orientation direction, but it becomes ≈0 after heating to 150°C. Electron diffractometry shows that the islands are elongated. TGA results show that the thermal degradation of the material in air plays a role only above 360°C. In general, the properties seem to depend on the extent of orientation but not on the nature of the field such as shear or magnetic.

A 58-year-old male baseball coach with a prepectoral dual-chamber permanent pacemaker (Accent DR 2210; St. Jude Medical) implanted for sinus node dysfunction was evaluated for a pocket hematoma after he was hit by a baseball over the pacemaker. Data from the pacemaker showed normal atrial and ventricular capture, but …

The relationship between cardiac and atrial fibrosis, and atrial fibrillation (AF) is well established. The objective of this study is to evaluate the relationship between CHADS2-VASc score and LA fibrosis. A cross-sectional study of patients with LA fibrosis scores was performed. Participants

Atrial fibrillation (AF) results in remodeling/fibrosis of the left atrium (LA). This relationship is modified by multiple factors. The objective of this study is to determine which factors have the strongest association with left atrial (LA) fibrosis using late gadolinium-enhancement cardiovascular

Atrial fibrillation (AF) increases by fivefold a patient's risk for thromboembolic stroke. The main source of emboli in AF is the left atrial appendage (LAA). Therefore, LAA closure could reduce the risk for thromboembolic events in AF. The investigators report the first United States experience with a novel percutaneous LAA closure device, the Lariat snare device, and its outcomes in 21 patients with AF, CHADS2 scores ≥2, and contraindications to anticoagulation. The LAA was closed with a snare containing suture from within the pericardial space. The intraoperative success of the procedure was confirmed by left atrial angiography and transesophageal echocardiographic color Doppler flow. The effectiveness of the procedure was evaluated by follow-up transesophageal echocardiography. The incidence of periprocedural and short-term complications was assessed by reviewing medical records. Twenty patients (100%) had successful LAA exclusion that was preserved at 96 ± 77 days. No patient had a stroke during an average of 352 ± 143 days of follow-up. One patient had right ventricular perforation and tamponade that required surgical exploration and repair. Two patients required prolonged hospitalization: 1 because of pericardial effusion that required repeat pericardiocentesis and 1 because of noncardiac co-morbidities. Three patients developed pericarditis1 month after the procedure, of whom 1 had associated pericardial effusion that required drainage. In conclusion, percutaneous LAA exclusion can be achieved successfully and with an acceptable incidence of periprocedural and short-term complications. Further studies are needed to determine whether LAA exclusion lowers the long-term risk for thromboembolic events in patients with AF and contraindications to anticoagulation.

Background: OCT with its unique image resolution is the ideal method to detect culprit lesion characteristics in different clinical presentations. The identification of inflammatory markers related to plaque characteristics may be of clinical importance. Methods: Thirty-two patients with acute coronary syndromes (ACS) and fourteen patients with stable angina pectoris (SAP) were enrolled in this study. Culprit lesion morphology was assessed by optical coherence tomography (OCT) in patients with ACS and SAP. The possible relations between serum levels of high sensitivity-C reactive protein (hs-CRP) and interleukin-18 (IL-18) with plaque characteristics were investigated in those patients. Results: Plaque rupture and thin-cap fibroatheroma (TCFA) were detected more frequently in ACS patients compared with SAP patients, (78.6% vs. 14.3%, p4.5 mg/L could detect ruptured plaque with a sensitivity of 91.7% and a specificity of 77.8%. Conclusions: OCT detected plaque rupture and TCFA more frequent in ACS patients compared with SAP. Elevated hs-CRP and IL-18 were positively related to plaque instability and rupture. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

164 σ., Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία, Η παρούσα μεταπτυχιακή εργασία πραγματεύεται την ελαστοπλαστική ανάλυση ραβδωτών φορέων με χαλάρωση υλικού και τη μελέτη της συμπεριφοράς τους. Συγκεκριμένα, κατ’ αρχήν εξετάζονται σε θεωρητικό επίπεδο, οι βασικές αρχές της πλαστικής ανάλυσης και ειδικότερα, ο τρόπος με τον οποίο ο γραμμικός προγραμματισμός μπορεί να εφαρμοστεί σε θέματα οριακής ανάλυσης και να αποτελέσει ένα χρήσιμο εργαλείο για την εξαγωγή αποτελεσμάτων με μεγάλη ακρίβεια. Η θεωρητική ανάλυση υποστηρίζεται από αριθμητικές εφαρμογές, με χρήση λογιστικών φύλλων Excel αλλά και ανάπτυξη κώδικα στη γλώσσα προγραμματισμού Matlab. Σε όλα τα παραδείγματα αυτής της ενότητας, υιοθετείται ελαστική – απόλυτα πλαστική συμπεριφορά υλικού και εξετάζονται πλαισιωτοί φορείς. Μελετάται η καθαρά καμπτική συμπεριφορά των φορέων και επίσης, η επιρροή της αλληλεπίδρασης των αξονικών δυνάμεων, είτε μέσω της ακριβούς μη γραμμικής σχέσης της επιφάνειας διαρροής των Masonet & Save (κατάλληλη για μεταλλικές κατασκευές), είτε με προσεγγιστικά γραμμικοποιημένα μοντέλα. Στην επόμενη ενότητα της εργασίας, αναλύεται, καταρχήν σε θεωρητικό επίπεδο, η έννοια της γραμμικής συμπληρωματικότητας (Linear Complementarity Problem). Ειδικότερα, επεξηγείται η δομή του προβλήματος, εξετάζεται η μεγάλη σημασία του σε θέματα μαθηματικού προγραμματισμού και παρουσιάζονται ορισμένες από τις σημαντικότερες εφαρμογές του στον τομέα του Πολιτικού Μηχανικού αλλά και των οικονομικών επιστημών. Κατόπιν αναπτύσσεται η θεωρητική έννοια της χαλάρωσης του υλικού (softening) και το πώς μπορεί να επιλυθεί ένα πρόβλημα ελαστοπλαστικής ανάλυσης σε ραβδωτούς φορείς που χαρακτηρίζονται από μια τέτοια συμπεριφορά, με τη χρήση του μαθηματικού προγραμματισμού και κυρίως μέσω της γραμμικής συμπληρωματικότητας. Με βάση τα ανωτέρω, αναπτύχθηκε κώδικας στη γλώσσα προγραμματισμού Matlab, o οποίος μπορεί να διεξάγει μια ελαστοπλαστική ανάλυση σε ραβδωτούς φορείς με χαλάρωση υλικού. Ακολουθούν αριθμητικά παραδείγματα, τα οποία παρουσιάζουν κλιμακούμενη δυσκολία (από το απλό θεωρητικό παράδειγμα μιας αμφίπακτης δοκού, σε ένα πλαίσιο τριών ανοιγμάτων και πέντε ορόφων με παρουσία έκκεντρων συνδέσμων δυσκαμψίας). Ο στόχος είναι να εξαχθούν διαγράμματα δύναμης – μετατόπισης και να γίνει σύγκριση στις παρακάτω συμπεριφορές της κατασκευής: Α) Ελαστική – απόλυτα πλαστική συμπεριφορά (elastic – perfectly plastic) Β) Καθαρά καμπτική συμπεριφορά με χαλάρωση υλικού (pure bending and softening) Γ) Αλληλεπίδραση αξονικής δύναμης και χαλάρωση υλικού (interaction and softening) Στην τελευταία ενότητα της εργασίας, εξετάζονται, αρχικά σε θεωρητικό επίπεδο, οι διαφοροποιήσεις του προβλήματος εάν πρέπει να ληφθεί υπόψη και η γεωμετρική μη γραμμικότητα και τα φαινόμενα 2ας τάξης. Αναπτύχθηκε και πάλι ένας τροποποιημένος κώδικας στη γλώσσα προγραμματισμού Matlab, ο οποίος προβλέπει και την παρουσία γεωμετρικών μη γραμμικοτήτων. Τα αριθμητικά παραδείγματα που ακολουθούν είναι τα ίδια με αυτά της προηγούμενης ενότητας, ώστε να επιτευχθεί η σύγκριση των αποτελεσμάτων και να διερευνηθεί το μέγεθος της επίδρασης των φαινομένων δευτέρας τάξης στη συνολική συμπεριφορά του φορέα. Η σύγκριση των αναλύσεων γίνεται στη γενική περίπτωση της αλληλεπίδρασης αξονικής δύναμης με χαλάρωση υλικού. Από τα αποτελέσματα των εφαρμογών σε όλες τις ενότητες τις εργασίας, προέκυψαν συμπεράσματα τα οποία αναλύονται στο κείμενο που ακολουθεί, καθώς και σκέψεις για μελλοντική έρευνα που μπορεί να γίνει στο πεδίο αυτής της μεταπτυχιακής εργασίας., The current master thesis explores the elastoplastic analysis of frame structures with softening and the characteristics of their behavior. Firstly, the basic principles of plastic analysis are examined and especially the applications of linear programming at limit analysis and how it can become a useful tool for the extraction of highly accurate results. The theoretical presentation is supported through some numeric applications, with the use of EXCEL spreadsheets and also the development of a program code at the programming language MATLAB. In all the examples of that part, an elastic – perfectly plastic behavior is adopted and exclusively frame structures are analyzed. The pure bending behavior and the interaction of axial forces through the exact non – linear relationship of Massonet & Save (suitable for steel structures) or through approximate linearized yield surfaces is examined. At the next part of this thesis, the theoretical background of linear complementarity problem is explained. More specifically, the thesis focus on the problem’s structure (LCP) and its great importance in the field of mathematical programming. In addition, some of the applications of that problem to the science of civil engineer and also to the area of economics are discussed. Finally, the concept of softening is developed and special attention is paid to the formulation of a problem of elastoplastic analysis at softening structures using mathematical programming and the principles of the linear complementarity problem. Based on the above theoretical analysis, a program code at MATLAB was developed in order to analyze such softening frames. Some numeric applications follow which are categorized by their complexity (beginning from the simple example of a simple double clamped beam and concluding to the more complex application of a three bay and five storey eccentrically braced frame). The target is to extract force – displacement diagrams and to make a comparison to the following structural behaviors: A) Elastic – perfectly plastic behavior B) Pure bending and softening C) Interaction of axial forces and softening At the last part of the thesis the differentiations of the above problem including second order effects are traced. A verified program code using MATLAB was developed, whose main characteristic is to embody the influence of such geometric non-linearity during the structural analysis. The numeric examples that follow are exactly the same with those of the previous chapter, because it was considered important to compare the results and explore the influence of such phenomena to the overall response of the frames. The comparison of the results takes place at the general case of interaction and softening. The results of the applications in this thesis lead to some important conclusions that are referred to the last chapter. Finally, some thoughts for future research in the field of this thesis are expressed.

OCT with its unique image resolution is the ideal method to detect culprit lesion characteristics in different clinical presentations. The identification of inflammatory markers related to plaque characteristics may be of clinical importance.Thirty-two patients with acute coronary syndromes (ACS) and fourteen patients with stable angina pectoris (SAP) were enrolled in this study. Culprit lesion morphology was assessed by optical coherence tomography (OCT) in patients with ACS and SAP. The possible relations between serum levels of high sensitivity-C reactive protein (hs-CRP) and interleukin-18 (IL-18) with plaque characteristics were investigated in those patients.Plaque rupture and thin-cap fibroatheroma (TCFA) were detected more frequently in ACS patients compared with SAP patients, (78.6% vs. 14.3%, p0.001, 92.9% vs. 14.3%, p0.001, respectively). Higher levels of serum hs-CRP and IL-18 were found in patients with plaque rupture vs. those with no plaque rupture (median value: 19.2mg/L vs. 1.6 mg/L, p0.001 and 219.5 pg/ml vs. 127.5 pg/ml, p=0.001 respectively), and TCFA vs. those without TCFA (median value: 15.2mg/L vs. 1.6 mg/L, p=0.004 and 209.0 pg/ml vs.153.2 pg/ml, p=0.03 respectively). Serum hs-CRP was the only independent predictor of plaque rupture (p=0.02, odds ratio 1.1, 95% confidence interval 1.0 to 1.2). A cut-off value of hs-CRP4.5mg/L could detect ruptured plaque with a sensitivity of 91.7% and a specificity of 77.8%.OCT detected plaque rupture and TCFA more frequent in ACS patients compared with SAP. Elevated hs-CRP and IL-18 were positively related to plaque instability and rupture.

Some individuals with mutations in the cardiac ryanodine receptor gene (RyR2) develop stress-induced atrial fibrillation (AF), but the underlying mechanisms are unknown. This study explored the molecular basis of AF susceptibility in mice heterozygous for the human arrhythmia-linked RyR2 mutation R176Q (RQ mice). AF inducibility was assessed with atrial burst pacing in WT (n=34), RQ mice (n=43) and RQ mice crossed with transgenic mice expressing the CaMKII-inhibitory peptide AC3I (RQxAC3I, n=6) or the inactive analog AC3C (RQxAC3C, n=9). Dual voltage (RH237) and calcium (Rhod-2 AM) optical mapping was applied to monitor simultaneous Ca2+ and membrane-voltage changes. Ca2+ fluorescence (Fluo-4 AM) was used to study SR Ca2+ release. Expression/phosphorylation of CaMKII and RyR2 were determined by immunostaining in mice and human atrial biopsies from sinus rhythm (SR) (n=7) and chronic AF (n=7) patients. Atrial burst pacing-induced AF was more common in RQ (55%) than in WT mice (11%*; *P This research has received full or partial funding support from the American Heart Association, AHA South Central Affiliate (Arkansas, New Mexico, Oklahoma & Texas).

BACKGROUND: Although defective Ca(2+) homeostasis may contribute to arrhythmogenesis in atrial fibrillation (AF), the underlying molecular mechanisms remain poorly understood. Studies in patients with AF revealed that impaired diastolic closure of sarcoplasmic reticulum (SR) Ca(2+)-release channels (ryanodine receptors, RyR2) is associated with reduced levels of the RyR2-inhibitory subunit FKBP12.6. OBJECTIVE: The objective of the present study was to test the hypothesis that Ca(2+) leak from the SR through RyR2 increases the propensity for AF in FKBP12.6-deficient (-/-) mice. METHODS: Surface electrocardiogram and intracardiac electrograms were recorded simultaneously in FKBP12.6-/- mice and wild-type (WT) littermates. Right atrial programmed stimulation was performed before and after injection of RyR2 antagonist tetracaine (0.5 mg/kg). Intracellular Ca(2+) transients were recorded in atrial myocytes from FKBP12.6-/- and WT mice. RESULTS: FKBP12.6-/- mice had structurally normal atria and unaltered expression of key Ca(2+)-handling proteins. AF episodes were inducible in 81% of FKBP12.6-/-, but in only 7% of WT mice (P

Ventricular arrhythmias deteriorating into sudden cardiac death are a major cause of mortality worldwide. The recent linkage of a genetic form of cardiac arrhythmia to mutations in the gene encoding RyR2 (ryanodine receptor 2) has uncovered an important role of this SR (sarcoplasmic reticulum) calcium release channel in triggering arrhythmias. Mutant RyR2 channels give rise to spontaneous release of calcium (Ca2+) from the SR during diastole, which enhances the probability of ventricular arrhythmias. Several molecular mechanisms have been proposed to explain the gain-of-function phenotype observed in mutant RyR2 channels. Despite considerable differences between the models discussed in the present review, each predicts spontaneous diastolic Ca2+ leak from the SR due to incomplete closure of the RyR2 channel. Enhanced SR Ca2+ leak is also observed in common structural diseases of the heart, such as heart failure. In heart failure, defective channel regulation in the absence of inherited mutations may also increase SR Ca2+ leak and initiate cardiac arrhythmias. Therefore inhibition of diastolic Ca2+ leak through SR Ca2+ release channels has emerged as a new and promising therapeutic target for cardiac arrhythmias.

An 86-year-old white male brought to the emergency room for weakness and lethargy was found to have third degree AV block with a left bundle branch escape rhythm ( Figure 1A ). An Advisa MRI® (Medtronic) dual-chamber pacemaker was implanted. Telemetry tracings revealed asymptomatic episodes of isolated …

Let A_1,A_2,...,A_s be a finite sequence of (not necessarily disjoint, or even distinct) non-empty sets of positive integers satisfying a certain condition. It is shown that an independent family U_1,U_2,...,U_s of random NxN permutation matrices with cycle lengths restricted to A_1,A_2,...,A_s, respectively, converges in *-distribution as N goes to infinity to to a *-free family u_1,u_2,...,u_s of non-commutative random variables with each u_r a Haar unitary (if A_r is an infinite set) or a d_r-Haar unitary (if A_r is a finite set and d_r=sup A_r).Under an additional assumption on the sets A_1,A_2,...,A_s, it is shown that the convergence in *-distribution actually holds almost surely., 27 pages, 2 figures; substantial modifications were made (especially to section 4), leading to a new almost sure convergence result stated as part of the main theorem

Malignant hyperthermia (MH) is a life-threatening disorder characterized by skeletal muscle rigidity and elevated body temperature in response to halogenated anesthetics such as isoflurane or halothane. Mutation of tyrosine 522 of RyR1 (the predominant skeletal muscle calcium release channel) to serine has been associated with human malignant hyperthermia. In the present study, mice created harboring this mutation were found to represent the first murine model of human malignant hyperthermia. Mice homozygous for the Y522S mutation exhibit skeletal defects and die during embryonic development or soon after birth. Heterozygous mice, which correspond to the human occurrence of this mutation, are MH susceptible, experiencing whole body contractions and elevated core temperatures in response to isoflurane exposure or heat stress. Skeletal muscles from heterozygous mice exhibit increased susceptibility to caffeine- and heat-induced contractures in vitro. In addition, the heterozygous expression of the mutation results in enhanced RyR1 sensitivity to activation by temperature, caffeine, and voltage but not uncompensated sarcoplasmic reticulum calcium leak or store depletion. We conclude that the heterozygous expression of the Y522S mutation confers susceptibility to both heat- and anesthetic-induced MH responses.

The present paper proposes an original analytical solution of the thermohydrodynamic lubrication, and the validation of the model in the case of journal bearings. The simplicity and accuracy of the method and the computing times of the order of seconds necessary for bearing estimation constitute important advantages of this model over the numerical method.Copyright © 2005 by ASME

The paper makes a succinct analysis of the advantages and limitations of the differential equation for pressures proposed by Ionescu [1]. The main theoretical and experimental aspects concerning the quantitative estimation of journal bearings are briefly presented. A variant of the equation ensuring calculation accuracy for lightly loaded bearings is proposed.Copyright © 2005 by ASME

We show that an independent family of uniformly distributed random permutation matrices is asymptotically *-free from an independent family of square complex Gaussian matrices and from an independent family of complex Wishart matrices, and that in both cases the convergence in *-distribution actually holds almost surely. An immediate consequence is that, if the rows of a GUE matrix are randomly permuted, then the resulting (non self-adjoint) random matrix has a *-distribution which is asymptotically circular; similarly, a random permutation of the rows of a complex Wishart matrix results in a random matrix which is asymptotically *-distributed like an R-diagonal element from free probability theory., Comment: 22 pages, no figures; added section 4 and minor modifications to sections 1-3