Novel algorithms and rating methods for high-performance ECG classification

The electrocardiogram (ECG) is the most central information provider for the diagnosis of cardiac diseases. Today, the computer-aided analysis of short-term ECG-recordings in supine rest, the OR or the ICU is a well-established procedure. One major problem, though, is to track the presence and the amount of arrhythmias over days, weeks and month. As cardiologists can not spend their time on analyzing millions of heart beats for a single patient, an automated computer algorithm is necessary. Those ECG-classifiers assign heart beats to their respective type of arrhythmia or heart rhythm type. Analyzing the current state-of-the-art is obligatory, but quite cumbersome. Performance measures can be misleading. Data is sometimes collected to the advantage of certain classifiers. Therefore, this thesis calculates the same performance criterion for all publications and assesses the likelihood for the reported performance to be achieved in real-life situations. For the purpose of the latter, this thesis introduces the � -Score which rates each classifier towards eight different aspects by qualitative and quantitative criteria. The final review of 72 ECG-classifiers presents new insights towards the current frontier of research in the field. This thesis transcends this border by exploiting over 1.4 million features incorporating features derived from common methods like wavelet transformation, time-domain analysis, autoregressive models and from novel ones like the 2D-segmentation of the bi-spectrum, static delineation and heavy use of partition functions and relational features. In contrast to current practice, this thesis extracts its features from three different segments using several normalization strategies instead of a single one, fixed with respect to size and position. However, those 1.4 million features have to be reduced to a set of 20 to 60 highly relevant ones. The most potent strategies for this amount of data reside in the text-categorization domain. Unluckily, those techniques are neither geared to process continuous real valued data nor to account for multi-class classification tasks. That is why this thesis extends those strategies to cope with cardinal data by creating new measures of effect size and novel strategies of combining them with regard to a multi-class scenario. The final classifier employs support vector machines. During the course of the thesis, over 200,000 wellconfigured SVMs had to be calculated for certain experiments, necessitating 400 configurations per SVM to be tested. This number could be reduced to 7 by revealing a yet undiscovered connection between the optimal kernel-band-width for time-histograms and the optimal configuration of non-linear SVMs, saving much computation time.Seit Jahrzehnten dient das Elektrokardiogramm, kurz EKG, der Diagnose von Herzkrankheiten. Sowohl im Operationssaal als auch auf der Intensivstation helfen schon heute computergestützte Analysen des EKGs die Therapie der Patienten zu verbessern. Bisher werden jedoch vor allem die Herzrate und nur auf kurzen Zeitskalen die Morphologie der einzelnen Herzschläge untersucht. Um die Morphologie der Herzschläge auch über Tage, Wochen oder gar Monate zuverlässig bewerten zu können, sind hochleistungsfähige EKG-Klassifikatoren notwendig, welche jedem Herzschlag automatisiert einen bestimmten Typ zuordnen. Der aktuelle Stand der Forschung bezüglich EKG-Klassifikatoren und die damit verbundene “Frontier of research” lassen sich nur schwer bestimmen. Zum einen wird kein einheitliches Gütemaß verwendet. Zum anderen variiert die Datenbasis auf der diese Güte erzielt wurde stark. Darum wurde in dieser Arbeit erstmal ein einheitliches Gütemaß für 72 Klassifikatoren angewendet und die Datenbasis mit Hilfe des neu-entwickelten � -Score’s bewertet. Dieser ist ein Maß für die Wahrscheinlichkeit, dass die angegebene Güte auch unter Realbedingungen erreicht werden kann. Der EKG-Klassifikator der in dieser Arbeit vorgestellt werden soll, geht über den aktuellen Stand der Forschung deutlich hinaus. Hierzu werden zunächst 1,4 Millionen EKG-Merkmale extrahiert und anschließend mit neuen Verfahren zur Merkmalsselektion auf 20-60 Merkmale reduziert. Bei der Extraktion kommen sowohl bekannte Methoden wie dieWavelet-Transformation und Zeitreihenanalysen, sowie neuartigen Verfahren zur Auswertung des zweidimensional-segmentierten Bispektrums, der statischen Beschreibung des EKGs und der Verwendung von Partitionsfunktionen und relationalen Merkmalen zum Einsatz. Weiterhin werden erstmals Merkmale aus 3 verschiedenen Segmenten mit unterschiedlichen Normalisierungen extrahiert. Typischerweise wird nur ein festes EKG-Segment für jeden Herzschlag verwendet. Die geeignetsten Verfahren zur Merkmalsselektion für diese Menge an Daten stammen aus dem Bereich der Textkategorisierung (z.B. Spam-Filter). Unglücklicherweise sind diese Techniken nicht für kardinale Daten ausgelegt und funktionieren vor allem bei binären Problemen (Spam bzw. kein-Spam). Daher erweitert diese Arbeit die Textkategorisierungstrategien auf reelle Daten und schlägt Methoden vor, um diese in meinem multiklassen Szenario (normaler Herzschlag, Arrhythmie 1-12) einsetzen zu können. Die endgültige Klassifikation geschieht mittels Support Vector Machines. Im Verlauf der Arbeit mussten für die verschiedensten Experimente insgesamt über 200.000 optimal konfigurierte SVMs erstellt werden. Jede einzelne SVM müsste normalerweise mit ca. 400 Konfigurationen getestet werden. Diese Zahl konnte auf 7 und die Gesamtrechenzeit deutlich reduziert werden. Dies war möglich durch dass Ausnutzen eine bislang unbekannten Zusammenhangs zwischen der optimalen Kernel-Bandbreite bei Zeithistogrammen und der optmimalen Konfiguration der nicht-linearen SVM

Hyaluronic acid levels predict risk of hepatic encephalopathy and liver-related death in HIV/viral hepatitis coinfected patients

Background: Whereas it is well established that various soluble biomarkers can predict level of liver fibrosis, their ability to predict liver-related clinical outcomes is less clearly established, in particular among HIV/viral hepatitis co-infected persons. We investigated plasma hyaluronic acid’s (HA) ability to predict risk of liver-related events (LRE; hepatic coma or liver-related death) in the EuroSIDA study. Methods: Patients included were positive for anti-HCV and/or HBsAg with at least one available plasma sample. The earliest collected plasma sample was tested for HA (normal range 0–75 ng/mL) and levels were associated with risk of LRE. Change in HA per year of follow-up was estimated after measuring HA levels in latest sample before the LRE for those experiencing this outcome (cases) and in a random selection of one sixth of the remaining patients (controls). Results: During a median of 8.2 years of follow-up, 84/1252 (6.7%) patients developed a LRE. Baseline median (IQR) HA in those without and with a LRE was 31.8 (17.2–62.6) and 221.6 ng/mL (74.9–611.3), respectively (p<0.0001). After adjustment, HA levels predicted risk of contracting a LRE; incidence rate ratios for HA levels 75–250 or ≥250 vs. <75 ng/mL were 5.22 (95% CI 2.86–9.26, p<0.0007) and 28.22 (95% CI 14.95–46.00, p<0.0001), respectively. Median HA levels increased substantially prior to developing a LRE (107.6 ng/mL, IQR 0.8 to 251.1), but remained stable for controls (1.0 ng/mL, IQR –5.1 to 8.2), (p<0.0001 comparing cases and controls), and greater increases predicted risk of a LRE in adjusted models (p<0.001). Conclusions: An elevated level of plasma HA, particularly if the level further increases over time, substantially increases the risk of contracting LRE over the next five years. HA is an inexpensive, standardized and non-invasive supplement to other methods aimed at identifying HIV/viral hepatitis co-infected patients at risk of hepatic complications

Intensive language training enhances brain plasticity in chronic aphasia

BACKGROUND: Focal clusters of slow wave activity in the delta frequency range (1–4 Hz), as measured by magnetencephalography (MEG), are usually located in the vicinity of structural damage in the brain. Such oscillations are usually considered pathological and indicative of areas incapable of normal functioning owing to deafferentation from relevant input sources. In the present study we investigated the change in Delta Dipole Density in 28 patients with chronic aphasia (>12 months post onset) following cerebrovascular stroke of the left hemisphere before and after intensive speech and language therapy (3 hours/day over 2 weeks). RESULTS: Neuropsychologically assessed language functions improved significantly after training. Perilesional delta activity decreased after therapy in 16 of the 28 patients, while an increase was evident in 12 patients. The magnitude of change of delta activity in these areas correlated with the amount of change in language functions as measured by standardized language tests. CONCLUSIONS: These results emphasize the significance of perilesional areas in the rehabilitation of aphasia even years after the stroke, and might reflect reorganisation of the language network that provides the basis for improved language functions after intensive training

Is there Emergence of Clinical HBV Resistance Under Long-Term HBV Combination Therapy? A Challenging Case Report

A first case of clinical tenofovir (TDF) HBV resistance in an HIV/HBV coinfected patient who developed an acute flare of hepatitis B is reported. The clinical course was accompanied by signs of acute liver failure after being on successful HBV treatment with tenofovir and persistently undetectable HBV-DNA viral load for over five years

Hyaluronic acid levels predict risk of hepatic encephalopathy and liver-related death in HIV/viral hepatitis coinfected patients

Background: Whereas it is well established that various soluble biomarkers can predict level of liver fibrosis, their ability to predict liver-related clinical outcomes is less clearly established, in particular among HIV/viral hepatitis co-infected persons. We investigated plasma hyaluronic acid's (HA) ability to predict risk of liver-related events (LRE; hepatic coma or liver-related death) in the EuroSIDA study. Methods: Patients included were positive for anti-HCV and/or HBsAg with at least one available plasma sample. The earliest collected plasma sample was tested for HA (normal range 0-75 ng/mL) and levels were associated with risk of LRE. Change in HA per year of follow-up was estimated after measuring HA levels in latest sample before the LRE for those experiencing this outcome (cases) and in a random selection of one sixth of the remaining patients (controls). Results: During a median of 8.2 years of follow-up, 84/1252 (6.7%) patients developed a LRE. Baseline median (IQR) HA in those without and with a LRE was 31.8 (17.2-62.6) and 221.6 ng/mL (74.9-611.3), respectively (p,0.0001). After adjustment, HA levels predicted risk of contracting a LRE; incidence rate ratios for HA levels 75-250 or $250 vs. ,75 ng/mL were 5.22 (95% CI 2.86-9.26, p,0.0007) and 28.22 (95% CI 14.95-46.00, p,0.0001), respectively. Median HA levels increased substantially prior to developing a LRE (107.6 ng/mL, IQR 0.8 to 251.1), but remained stable for controls (1.0 ng/mL, IQR -5.1 to 8.2), (p,0.0001 comparing cases and controls), and greater increases predicted risk of a LRE in adjusted models (p,0.001). Conclusions: An elevated level of plasma HA, particularly if the level further increases over time, substantially increases the risk of contracting LRE over the next five years. HA is an inexpensive, standardized and non-invasive supplement to other methods aimed at identifying HIV/viral hepatitis co-infected patients at risk of hepatic complications

Essentials from the 2015 European AIDS Clinical Society (EACS) guidelines for the treatment of adult HIV-positive persons

BACKGROUND: The European AIDS Clinical Society (EACS) guidelines are intended for all clinicians involved in the care of HIV-positive persons, and are available in print, online, and as a free App for download for iPhone and Android. GUIDELINE HIGHLIGHTS: The 2015 version of the EACS guidelines contains major revisions in all sections; antiretroviral treatment (ART), comorbidities, coinfections and opportunistic diseases. Among the key revisions is the recommendation of ART for all HIV-positive persons, irrespectively of CD4 count, based on the Strategic Timing of AntiRetroviral Treatment (START) study results. The recommendations for the preferred and the alternative ART options have also been revised, and a new section on the use of pre-exposure prophylaxis (PrEP) has been added. A number of new antiretroviral drugs/drug combinations have been added to the updated tables on drug-drug interactions, adverse drug effects, dose adjustment for renal/liver insufficiency and for ART administration in persons with swallowing difficulties. The revisions of the coinfection section reflect the major advances in anti-hepatitis C virus (HCV) treatment with direct-acting antivirals with earlier start of treatment in individuals at increased risk of liver disease progression, and a phasing out of interferon-containing treatment regimens. The section on opportunistic diseases has been restructured according to individual pathogens/diseases and a new overview table has been added on CD4 count thresholds for different primary prophylaxes. CONCLUSIONS: The diagnosis and management of HIV infection and related coinfections, opportunistic diseases and comorbidities continue to require a multidisciplinary effort for which the 2015 version of the EACS guidelines provides an easily accessable and updated overview

Regionale Wertschöpfungsketten für ökologische Tier- und Fleischprodukte (REGINA): Abschlussbericht zur Machbarkeitsstudie

Die Broschüre beinhaltet eine Machbarkeitsstudie für eine digitale Plattform zur gemeinsamen regionalen Vermarktung im Ökolandbau. Eine solche Plattform ermöglicht eine bessere Direktvermarktung ökologisch erzeugter Produkte. Die Broschüre enthält eine ausführliche Anleitung, wie eine solche Vermarktungsplattform entwickelt und betrieben werden kann. Die Machbarkeitsstudie richtet sich an Landwirte, Verarbeiter und Vermarkter von Lebensmitteln sowie an Entwickler digitaler Plattformen. Redaktionsschluss: 31.05.202

Digitaler Marktplatz für ökologisch erzeugte tierische Lebensmittel: Handlungsfelder für den Aufbau eines digitalen Marktplatzes: Praxisleitfaden

Wie können Landwirte gemeinsam digital ihre Produkte vermarkten? Der Leitfaden gibt Antworten zu den wichtigsten Handlungsfeldern für den Aufbau eines digitalen Marktplatzes für ökologisch erzeugte tierische Lebensmittel. Redaktionsschluss: 30.05.202