Background: Ischaemic heart disease is a diagnostic and therapeutic challenge to most general practitioners. We sought to identify diagnostic characteristics and prognoses of patients in primary care that received exercise electrocardiography (ECG). We compared the ECG test results with respect to probability of subsequent cardiologist referrals. We also aimed to identify determinants for pre-hospital delays and lack of statin treatment before a first-time myocardial infarction (MI). Methods: Setting: Region of Jämtland Härjedalen, Sweden (adult population, approximately 99 000); study period 2010-2014. Patients and study designs: studies I and II: 865 patients referred to exercise ECG. Primary outcome: Incidence of cardiovascular events (I) and cardiologist referrals within six months after exercise ECG (II). Observed outcomes were compared to predictions from multivariable logistic models. Study III: 265 patients with first-time MI. Characteristics were analysed for determinants of pre-hospital delay ≥ 2 hours. Study IV: Survey of 931 patients with first-time MI. Analyses of characteristics associated with rates of statin treatment in patients with previously diagnosed cardiovascular diseases (CVD). Results: Study I: Exercise test results were associated with exertional chest pain, a pathologic ST-T segment on resting ECG, angina diagnosis according to the patient's opinion, and medication for dyslipidaemia. Cardiovascular events occurred in 52.7%, 18.3%, and 2.0% of patients with positive (ST-segment depression >1mm and chest pain indicative of angina), inconclusive (ST depression or chest pain), or negative tests, respectively. Study II: Positive or inconclusive exercise tests were associated with cardiologist referrals. Among patients with positive exercise tests, referral rates decreased with age, after adjusting for co-morbidity. Self-employed women were referred to cardiologic evaluations more often than other employed women. Study III: The first medical contact was a primary care facility for 52.3% of patients. The pre-hospital delay time was ≥ 2 h for 67.0% of patients in primary care and 44.7% of patients that called emergency medical services or were self-referred to hospital. Study IV: Among patients with prior CVD, 34.5% received current statin treatment before for the first MI. Statin treatment rates decreased with age, after adjusting for CVD and diabetes; women ≥70 years old were treated half as often as men of the same age. Conclusions: Clinical characteristics can be used to identify patients at low risk of cardiac events. The prognosis in patients with a negative exercise ECG was benign for six months after the exercise ECG. Exercise tests are important for selecting patients that require cardiologic evaluations. Age, gender, and employment status interacted with rates of referrals for cardiac evaluation. The pre-hospital delay time was considerably prolonged, particularly when primary care was the first medical contact. Only one third of patients with a prior CVD received statin treatment. Pre-MI statin treatment decreased with age, particularly among women ≥70 years old. In making medical decisions, it is necessary to be aware of biases regarding age, gender, and socioeconomic status. Methodologies for case finding and follow-up need to be improved and implemented in clinical practice. Keywords: Exercise ECG, Ischaemic heart disease, Myocardial infarction, Pre-hospital delay, Primary care, Prognosis, Referral, Statins, Secondary prevention / Sammanfattning på svenska: Bakgrund och syfte: Patienter med ischemisk hjärtsjukdom (IHD) utgör en diagnostisk och terapeutisk utmaning för läkare inom primärvården. Arbets-EKG är en vanlig metod vid utredning av patienter som söker till primärvården för besvär som kan vara förorsakade av IHD. Vi undersökte primärvårdspatienter remitterade till arbets-EKG, med avseende på de kliniska karakteristika (egenskaper och symtom) som kunde associeras med resultatet av arbets-EKG och med prognosen inom sex månader efter undersökningen. Vi jämförde arbets-EKG-svaren med avseende på efterföljande remittering för utredning vid hjärtklinik. Vi kartlade även faktorer av betydelse för tidsfördröjningen före sjukhusvård och för sekundärpreventiv behandling med kolesterolsänkande läkemedel (statiner), före insjuknande i hjärtinfarkt. Metod: De studier som ingår i avhandlingsarbetet (studier I-IV) genomfördes i Region Jämtland och Härjedalen, befolkningsunderlag cirka 99 000 personer i åldrar från 20 år och äldre, under åren 2010-2014. Undersökta patienter och studiedesign: Studier I och II: Prospektiv studie av 865 patienter undersökta med arbets-EKG, klassificerade som: positivt arbets-EKG (dynamisk ST-sänkning >1mm under arbetsprov och bröstsmärta typisk för kärlkramp), inkonklusivt (ST-sänkning eller bröstsmärta) eller negativt arbets-EKG. Utfallsvariabler: hjärt-kärlhändelser (instabil kärlkrampssjukdom, hjärtinfarkt, öppen kranskärlsoperation, ballongvidgning av kranskärl och kardiovaskulära dödsfall) (I) och remittering för utredning vid hjärtklinik inom sex månader efter arbets-EKG (II). Observerade hjärt-kärlhändelser jämfördes med förväntat utfall, enligt multivariabla statistiska modeller. Studie III: Retrospektiv studie av 265 patienter med förstagångs hjärtinfarkt, analyserade med avseende på faktorer av betydelse för tid från symtomdebut och till sjukhusvård, med brytpunkten två timmar eller längre tid för vård på sjukhus. Studie IV: Tvärsnittsstudie av 931 patienter med förstagångs hjärtinfarkt. Patienter med tidigare hjärt-kärlsjukdom analyserades med avseende på statinbehandling före hjärtinfarkten. Resultat: Studie I: Faktorer associerade med arbets-EKG-resultatet (positivt eller inkonklusivt svar mot negativt svar) var: ansträngningskorrelerad bröstsmärta före arbetsprovet, ST-T-segmentsförändringar på vilo-EKG, kärlkrampsdiagnos enligt patientens egen bedömning, samt medicinering för förhöjda kolesterolvärden i blodet. Hjärt-kärlhändelser inträffade i 52.7%, 18.3%, och 2.0% bland patienter med positivt, inkonklusivt respektive negativt arbets-EKG. Studie II: Resultatet från arbets-EKG styrde remitteringen av patienter till hjärtklinik, med högre sannolikhet för remiss efter positivt test. Bland patienter med positivt arbets-EKG remitterades färre patienter vid stigande ålder, justerat för tidigare känd hjärt-kärlsjukdom. Egenföretagande kvinnor blev oftare remitterade än andra kvinnor, justerat för ålder, bröstsmärtesymtom och arbets-EKG-svar. Studie III: I 52.3% av samtliga fall var primärvården (personligt besök eller via telefonrådgivning) den första vårdkontakten för patienter med förstagångs hjärtinfarkt. Tidsfördröjningen före sjukhusvård var 2 timmar eller mer bland 67.0% av alla patienter från primärvården och 44.7% bland de patienter som först ringde larmcentralen (112) eller sökte direkt till sjukhusets akutmottagning. Studie IV: Patienter med tidigare konstaterad hjärt-kärlsjukdom hade en pågående statinbehandling i 34.5% av fallen, före insjuknandet i förstagångs hjärtinfarkt. Andelen patienter med pågående statinbehandling avtog med stigande ålder, justerat för diabetes och tidigare hjärt-kärlsjukdom. Kvinnor från 70 år och äldre erhöll statinbehandling hälften så ofta som jämförbara män. Slutsats: Patienter med låg risk för hjärt-kärlhändelser kan identifieras före remittering till arbets-EKG, med hjälp av kliniska karakteristika. Patienter med negativt svar på arbets-EKG har en god prognos, med få hjärt-kärlhändelser inom sex månader efter arbetsprovet. Urvalet av patienter som remitteras för fortsatt hjärtutredning styrs av resultatet från arbets-EKG, men interaktioner mellan ålder, kön och anställningsförhållanden påverkar sannolikheten för remittering. Tiden från symtomdebut och till sjukhusvård var avsevärt fördröjd, särskilt för de patienter som primärt kontaktade primärvården. Endast en tredjedel av alla patienter med tidigare konstaterad hjärt-kärlsjukdom hade en pågående statinbehandling vid hjärtinfarktinsjuknandet. Andelen patienter med pågående statinbehandling avtog med högre ålder, särskilt bland kvinnor från 70 års ålder och äldre. En ökad medvetenhet om hur ålder, kön och social ställning påverkar den medicinska beslutsprocessen är angelägen. Metoder för bättre identifiering och uppföljning av riskpersoner behöver utvecklas och införas i den medicinska verksamheten. Nyckelord och förklaringar: Arbets-EKG (kliniskt arbetsprov på ergometercykel med samtidig EKG-registrering), positivt arbets-EKG (talar för kärlkrampssjukdom), negativt arbets-EKG (talar för frånvaro av sjukdom). EKG (elektrokardiografi), hjärtinfarkt, ischemisk hjärtsjukdom (sjukdomstillstånd med otillräcklig blodtillförsel till hjärtat), sekundärprevention (förhindra återinsjuknande i tidigare genomliden sjukdom).

The non-invasive fetal ECG (NIFECG), derived from abdominal surface electrodes, offers novel diagnostic possibilities for prenatal medicine. Despite its straightforward applicability, NIFECG signals are usually corrupted by many interfering sources. Most significantly, by the maternal ECG (MECG), whose amplitude usually exceeds that of the fetal ECG (FECG) by multiple times. The presence of additional noise sources (e.g. muscular/uterine noise, electrode motion, etc.) further affects the signal-to-noise ratio (SNR) of the FECG. These interfering sources, which typically show a strong non-stationary behavior, render the FECG extraction and fetal QRS (FQRS) detection demanding signal processing tasks. In this thesis, several of the challenges regarding NIFECG signal analysis were addressed. In order to improve NIFECG extraction, the dynamic model of a Kalman filter approach was extended, thus, providing a more adequate representation of the mixture of FECG, MECG, and noise. In addition, aiming at the FECG signal quality assessment, novel metrics were proposed and evaluated. Further, these quality metrics were applied in improving FQRS detection and fetal heart rate estimation based on an innovative evolutionary algorithm and Kalman filtering signal fusion, respectively. The elaborated methods were characterized in depth using both simulated and clinical data, produced throughout this thesis. To stress-test extraction algorithms under ideal circumstances, a comprehensive benchmark protocol was created and contributed to an extensively improved NIFECG simulation toolbox. The developed toolbox and a large simulated dataset were released under an open-source license, allowing researchers to compare results in a reproducible manner. Furthermore, to validate the developed approaches under more realistic and challenging situations, a clinical trial was performed in collaboration with the University Hospital of Leipzig. Aside from serving as a test set for the developed algorithms, the clinical trial enabled an exploratory research. This enables a better understanding about the pathophysiological variables and measurement setup configurations that lead to changes in the abdominal signal's SNR. With such broad scope, this dissertation addresses many of the current aspects of NIFECG analysis and provides future suggestions to establish NIFECG in clinical settings.

The goal for this master thesis is to develop a prototype that uses ultra-wideband (UWB) communications to wirelessly transfer electrocardiogram (ECG) data from an ECG measurement unit to an Android device (smartphone or similar) which is used to process and display the ECG signals. The prototype should consist of two hardware nodes; (1) Node one having a ECG measurement unit (an AD8232 single lead heart rate monitor), an UWB communication module (a Decawave DWM1000 module) and a microcontroller (an Arduino DUE); and (2) Node two having an Android device (an Android smartphone), an UWB communication module (a Decawave DWM1000 module) and a microcontroller (an Arduino DUE). On Node one the AD8232 monitor for ECG measurements is connected to an analog input (with an analog to digital converter (ADC)) on the Arduino and the DWM1000 module is connected to the Arduino via serial peripheral interface (SPI). On Node two the DWM1000 is connected to the Arduino via SPI to receive ECG data from Node one, and the Arduino is connected to the smartphone through a serial USB cable with an USB on-the-go adapter to send the ECG data to the smartphone, where it is filtered and displayed with an Android application. The application has the potential to add, for example, ECG analysis for diagnosing heart activities with artificial intelligence (AI) and further transmit the ECG data for remote medical care. The Arduino is programmed in Arduino IDE (integrated development environment) to handle ECG measurements and UWB communications (transmitting and receiving ECG data), which is limited to a single UWB channel because of limitations of the DWM1000 module. The Android application is created using Android studio, and it can process (with a notch filter) and display 1-12 channel ECG. The prototype has been built and tested. The results show that a single lead ECG measurement can be sent via UWB communication to a smartphone to display in real time. Multiple data channels (1-12 analog inputs on the Arduino) can be multiplexed, transmitted and displayed in real time. This thesis concludes that UWB has huge development potential, and will likely be used for various wireless devices in the future.

The Hilbert transform is a widely used transform in signal processing. In this thesis we explore its use for three different applications: electrocardiography, the Hilbert-Huang transform and modulation. For electrocardiography, we examine how and why the Hilbert transform can be used for QRS complex detection. Also, what are the advantages and limitations of this method? The Hilbert-Huang transform is a very popular method for spectral analysis for nonlinear and/or nonstationary processes. We examine its connection with the Hilbert transform and show limitations of the method. Lastly, the connection between the Hilbert transform and single-sideband modulation is investigated.

In der vorliegenden Untersuchung wurde ein arbeitspsychologisches Problem thematisiert, dass in Mensch-Maschine-Systemen auftritt. <br /> In Mensch-Maschine-Systemen werden Informationen in kodierter Form ausgetauscht. Diese inhaltlich verkürzte Informationsübertragung hat den Vorteil, keine lange Zustandsbeschreibung zu benötigen, so dass der Mensch auf die veränderten Zustände schnell und effizient reagieren kann. Dies wird aber nur dann ermöglicht, wenn der Mensch die kodierten Informationen (Kodes) vorher erlernten Bedeutungen zuordnen kann. Je nach Art der kodierten Informationen (visuelle, akustische oder alphanumerische Signale) wurden Gestaltungsempfehlungen für Kodealphabete entwickelt. <br /> Für Operateure resultiert die mentale Belastung durch Dekodierungsprozesse vor allem aus dem Umfang des Kodealphabetes (Anzahl von Kodezeichen), der wahrnehmungsmäßigen Gestaltung der Kodes und den Regeln über die Zuordnung von Bedeutungen zu Kodezeichen. <br /> <br /> Die Entscheidung über die Güte von Kodealphabeten geschieht in der Arbeitspsychologie in der Regel über Leistungsindikatoren. Dies sind üblicherweise die zur Dekodierung der Kodes benötigte Zeit und dabei auftretende Zuordnungsfehler. Psychophysiologische Daten werden oft nicht herangezogen.<br /> Fraglich ist allerdings, ob Zeiten und Fehler allein verlässliche Indikatoren für den kognitiven Aufwand bei Dekodierungsprozessen sind, da im hochgeübten Zustand bei gleichen Alphabetlängen, aber unterschiedlicher Kodezeichengestaltung sich häufig die mittleren Dekodierungszeiten zwischen Kodealphabeten nicht signifikant unterscheiden und Fehler überhaupt nicht auftreten. <br /> Die in der vorliegenden Arbeit postulierte Notwendigkeit der Ableitung von Biosignalen gründet sich auf die Annahme, dass mit ihrer Hilfe zusätzliche Informationen über die mentale Beanspruchung bei Dekodierungsprozessen gewonnen werden können, die mit der Erhebung von Leistungsdaten nicht erfasst werden. Denn gerade dann, wenn sich die Leistungsdaten zweier Kodealphabete nicht unterscheiden, können psychophysiologische Daten unterschiedliche Aspekte mentaler Beanspruchung erfassen, die mit Hilfe von Leistungsdaten nicht bestimmt werden können. <br /> Daher wird in Erweiterung des etablierten Untersuchungsansatzes vorgeschlagen, Biosignale als dritten Datenbereich, neben Leistungsdaten und subjektiven Daten mentaler Beanspruchung, abzuleiten, um zusätzliche Informationen über die mentale Beanspruchung bei Dekodierungsprozessen zu erhalten.<br /> Diese Annahme sollte mit Hilfe der Ableitung von Biosignalen überprüft werden. <br /> <br /> Der Begriff mentaler Beanspruchung wird in der bisherigen Literatur nur unzureichend definiert und differenziert. Daher wird zur Untersuchung dieses Konzepts, die wissenschaftliche Literatur berücksichtigend, ein erweitertes Modell mentaler Beanspruchung vorgestellt.<br /> Dabei wird die mentale Beanspruchung abgegrenzt von der emotionalen Beanspruchung. Mentale Beanspruchung wird weiterhin unterschieden in psychomotorische, perzeptive und kognitive Beanspruchung. Diese Aspekte mentaler Beanspruchung werden jeweils vom psychomotorischen, perzeptiven oder kognitiven Aufwand der zu bearbeitenden Aufgabe ausgelöst.<br /> <br /> In der vorliegenden Untersuchung wurden zwei zentrale Fragestellungen untersucht:<br /> Einerseits wurde die Analyse der anwendungsbezogenen Frage fokussiert, inwieweit psychophysiologische Indikatoren mentaler Beanspruchung über die Leistungsdaten (Dekodierungszeiten und Fehleranzahl) hinaus, zusätzliche Informationen zur Bestimmung der Güte von Kodealphabeten liefern. <br /> Andererseits wurde der Forschungsaspekt untersucht, inwieweit psychophysiologische Indikatoren mentaler Beanspruchung die zur Dekodierung notwendigen perzeptiven und kognitiven Aspekte mentaler Beanspruchung differenzieren können. Emotionale Beanspruchung war nicht Gegenstand der Analysen, weshalb in der Operationalisierung versucht wurde, sie weitgehend zu vermeiden. Psychomotorische Beanspruchung als dritter Aspekt mentaler Beanspruchung (neben perzeptiver und kognitiver Beanspruchung) wurde für beide Experimentalgruppen weitgehend konstant gehalten.<br /> <br /> In Lernexperimenten hatten zwei anhand eines Lern- und Gedächtnistests homogenisierte Stichproben jeweils die Bedeutung von 54 Kodes eines Kodealphabets zu erwerben. Dabei wurde jeder der zwei unahbhängigen Stichproben ein anderes Kodealphabet vorgelegt, wobei sich die Kodealphabete hinsichtlich Buchstabenanzahl (Kodelänge) und anzuwendender Zuordnungsregeln unterschieden. Damit differierten die Kodealphabete im perzeptiven und kognitiven Aspekt mentaler Beanspruchung.<br /> Die Kombination der Abkürzungen entsprach den in einer Feuerwehrleitzentrale verwendeten (Kurzbeschreibungen von Notfallsituationen). In der Lernphase wurden den Probanden zunächst die Kodealphabete geblockt mit ihren Bedeutungen präsentiert. <br /> Anschließend wurden die Kodes (ohne deren Bedeutung) in sechs aufeinanderfolgenden Prüfphasen randomisiert einzeln dargeboten, wobei die Probanden instruiert waren, die Bedeutung der jeweiligen Kodes in ein Mikrofon zu sprechen. <br /> Während des gesamten Experiments wurden, neben Leistungsdaten (Dekodierungszeiten und Fehleranzahl) und subjektiven Daten über die mentale Beanspruchung im Verlauf der Experimente, folgende zentralnervöse und peripherphysiologische Biosignale abgeleitet: Blutdruck, Herzrate, phasische und tonische elektrodermale Aktivität und Elektroenzephalogramm. Aus ihnen wurden zunächst 13 peripherphysiologische und 7 zentralnervöse Parameter berechnet, von denen 7 peripherphysiologische und 3 zentralnervöse Parameter die statistischen Voraussetzungen (Einschlusskriterien) soweit erfüllten, dass sie in die inferenzstatistische Datenanalyse einbezogen wurden.<br /> <br /> Leistungsdaten und subjektive Beanspruchungseinschätzungen der Versuchsdurchgänge wurden zu den psychophysiologischen Parametern in Beziehung gesetzt. Die Befunde zeigen, dass mittels der psychophysiologischen Daten zusätzliche Erkenntnisse über den kognitiven Aufwand gewonnen werden können.<br /> <br /> Als weitere Analyse wurden die Kodes post hoc in zwei neue Kodealphabete eingeteilt. Ziel dieser Analyse war es, die Unterschiede zwischen beiden Kodealphabeten zu erhöhen, um deutlichere reizbezogene psychophysiologische Unterschiede in den EEG-Daten zwischen den Kodealphabeten zu erhalten. Dazu wurde diejenigen, hinsichtlich ihrer Bedeutung, parallelen Kodes in beiden Kodealphabeten ausgewählt, die sich in der Dekodierungszeit maximal voneinander unterschieden. Eine erneute Analyse der EEG-Daten erbrachte jedoch keine Verbesserung der Ergebnisse.<br /> <br /> Drei Hauptergebnisse bezüglich der psychophysiologischen Parameter konnten festgestellt werden:<br /> Das erste Ergebnis ist für die psychophysiologische Methodik bedeutsam. Viele psychophysiologische Parameter unterschieden zwischen den Prüfphasen und zeigen damit eine hinreichende Sensitivität zur Untersuchung mentaler Beanspruchung bei Dekodierungsprozessen an. Dazu gehören die Anzahl der spontanen Hautleitwertsreaktionen, die Amplitude der Hautleitwertsreaktionen, das Hautleitwertsniveau, die Herzrate, die Herzratendifferenz und das Beta-2-Band des EEG. Diese Parameter zeigen einen ähnlichen Verlauf wie die Leistungsdaten. Dies zeigt, dass es möglich ist, die hier operationaliserte Art mentaler Beanspruchung in Form von Dekodierungsprozessen psychophysiologisch zu analysieren.<br /> <br /> Ein zweites Ergebnis betrifft die Möglichkeit, Unterschiede mentaler Beanspruchung zwischen beiden Gruppen psychophysiologisch abzubilden:<br /> Das Hautleitwertsniveau und das Theta-Frequenzband des Spontan-EEG zeigten Unterschiede zwischen beiden Stichproben von der ersten Prüfphase an. Diese Parameter indizieren unterschiedlichen kognitiven Aufwand in beiden Stichproben über alle Prüfphasen.<br /> <br /> Das wichtigste Ergebnis betrifft die Frage nach einem Informationsgewinn bei Einsatz psychophysiologischer Methoden zur Bewertung der Güte von Kodealphabeten: <br /> Einen tatsächlichen Informationsgewinn gegenüber den Leistungsdaten zeigte die Amplitude der elektrodermalen Aktivität und die Herzraten-Differenz an. Denn in den späteren Prüfphasen, wenn sich die Leistungsdaten beider Kodealphabete nicht mehr unterschieden, konnten unterschiedliche Ausprägungen dieser psychophysiologischen Parameter zwischen beiden Kodealphabeten verzeichnet werden. Damit konnten unterschiedliche Aspekte mentaler Beanspruchung in beiden Kodealphabeten in den späteren Prüfphasen erfasst werden, in denen sich die Leistungsdaten nicht mehr unterschieden. <br /> <br /> Alle drei Ergebnisse zeigen, dass es, trotz erheblichen technischen und methodischen Aufwands, sinnvoll erscheint, bei der Charakterisierung mentaler Belastungen und für die Gestaltung von Kodealphabeten auch psychophysiologische Daten heranzuziehen, da zusätzliche Informationen über den perzeptiven und kognitiven Dekodierungsaufwand gewonnen werden können. / In this study a problem from the work psychology was focussed, which appears in human-machine systems.<br /> In human-machine systems informations were exchanged as codes. Using this kind of shortened information transmission needs no long description of the system state, so that the operator can react to the changed system state in a quick and efficient way. This is possible only in this case, if the operator has learned the meaning of the codes before. For the different kinds of coded informations (visual, acoustic or alphanumeric signals) special recommendations for their design were developed.<br /> Mental workload caused by decoding processes resulting from the size of the code alphabet, the percepted design of the codes, and the rules about the allocation of code meanings.<br /> <br /> The decision about the validity of code alphabets in work psychology is normally made by indicators of performance, which are the decoding times and decoding mistakes. Nearly all studies do not refer to psychophysiological data. <br /> It is questioned, if times and mistakes alone are valid indicators for the cognitive cost, because in well learned state and for the same size of the code alphabet but different design of the codes, the decoding times between code alphabets are not significantly different, and mistakes do not appear.<br /> This study postulates a necessity for the registration of psychophysiological data, so that additionally informations, which are not included in the performance data, can be examined. If the performance data does not differ between two code alphabets, psychophysiological data measures different aspects of mental workload, which could not be detected by performance data. To enlarge the established approach, it is recommended to registrate biosignals as a third domain of data to get additional informations about decoding processes.<br /> These hypotheses should be verified by registration of biosignals.<br /> <br /> There are vague definitions and deficient differentiations of the concept of mental workload in the scientific publications. To examine mental workload an enlarged model of mental workload is presented. Mental workload is delimited from emotional strain. Furthermore mental workload is differentiated in psychomotoric, perceptive, and cognitive aspects. These aspects of mental workload are caused by the psychomotoric, perceptive, and cognitive cost, which are initiated by the assigned task.<br /> <br /> Two main questions were examined in this study. <br /> First question refers to applied research. Do psychophysiological indicators of mental workload provide more information about the validity of code alphabets than performance data?<br /> The second question refers to what extent psychophysiological indicators of mental workload necessary for the decoding process could differentiate the perceptive and cognitive aspects of mental workload. <br /> <br /> >The emotional strain was not the objective of this study, therefore it was excluded from the experimental design.<br /> Psychomotoric workload as the third aspect of mental workload was a constant value for both experimental samples.<br /> <br /> In two learning experiments two samples with identical habituational memory performance were instructed to learn the meaning of 54 codes of a code alphabet. Both samples was presented another code alphabet, which differed in the number of included letters and the allocation rules. Thus the two code alphabets differed in the perceptive and in the cognitive aspect of mental workload.<br /> The combination of abbreviations was comparable to those used in a fire station. In a learning phase the code alphabets were presented with their meanings. Afterwards the codes were presented without their meanings in six following tests phases. Subjects were instructed to answer in a microphone. <br /> During the whole experiment performance data, subjective data of perceived strain, and psychophysiological data were registrated. The psychophysiological data contained: blood pressure, heart rate, phasic and tonic electrodermal activity, and the EEG. Thirteen peripherphysiological and seven EEG parameters were extracted from these raw data. Seven peripherphysiological and three EEG parameters accomplished the statistical premises and were included to further statistical analysis.<br /> Performance data and subjective data were set in relation to the psychophysiological parameters. The outcomes showed that using psychophysiological data generate additional informations about the cognitive cost.<br /> <br /> For further analysis the code items were divided into two new code alphabets. The intention of this analysis was to maximize the difference between the two code alphabets to get more stimuli based psychophysiological differences in the EEG data. This analysis included those pairs of codes with identical meaning and maximum difference in their decoding time. This further analysis did not improve the outcomes. <br /> <br /> Three main outcomes in respect to the psychophysiological data were detected. <br /> The first one is an important outcome for psychophysiological methodology. Many psychophysiological parameters differ between the test phases and thus show a sufficient sensitivity to examine mental workload in decoding processes. The number of spontaneous electrodermal responses, the amplitude of electrodermal responses, the electrodermal level, the heart rate, the heart rate difference, and the beta-2 frequency band of the EEG belong to these parameters. These parameters show a similar distribution like performance data. This shows the possibility of the operationalized mental workload through decoding processes analysable with psychophysiological methods.<br /> A second outcome concerns the possibility to show differences in mental workload between both samples in psychophysiological parameters:<br /> The electrodermal level and the theta frequency band of the EEG showed differences between both samples beginning from the first test phase. These parameters indicate different cognitive cost in both samples in all test phases.<br /> <br /> The most important outcome regards to the profit of information by using psychophysiological methods to test the validity of code alphabets. The amplitude of the electrodermal responses and the heart rate difference shows a surplus of information compared to performance data. Thus in later test phases, in which the performance data did no longer differ, different characteristics of psychophysiological parameters between both code alphabets were registrated. Therefore different aspects of mental workload could be quantified.<br /> <br /> All three outcomes showed that, nevertheless of the considerable technical and methodological expenditure, it is reasonable to use psychophysiological data to design code alphabets, because it supplies additional information about the perceptional and cognitive cost of the decoding processes.

No description available.

Ultra wideband (UWB) communications has been a subject of much discussion over the last decade. The method of UWB has had a hard time to establish itself among other methods such as Bluetooth and WiFi but as internet of things (IoT) gains a foothold in our daily lives, UWB has presented some new application areas. These application areas are, among other things, self driving cars, energy efficient data transfer, health care applications, sensor networks and real time location systems. This project aims to use UWB communications to real-world applications, specifically, electrocardiography (ECG) - an application in health care in this project, and develop a prototype for the application. The prototype consists of two Android smart phones and two UWB modules (EVK1000 evaluation kits from DecaWave, Inc). Each smartphone connects a UWB module so that the two smart phones, one as sender and the other as receiver, can communicate directly through UWB radios. This is intended to serve as a proof-of-concept that UWB devices are well suited for short range data transfer applications. The result achieved by the project is an android application along with sending and receiving programs for the development boards by Decawave and additional information regarding UWB and its uses. The results also include a comparison of UWB, Bluetooth and WiFi as of todays standard. The goal of the project is to learn how android applications are programmed, how UWB is used in todays technology and how to program and use development boards presented by companies. The prototype has been built and shown that 12-lead simulated ECGsignals from the sender can be transfered to the receiver through the UWB communications. The work includes programming (in C) the two UWB modules for UWB communications, and Java for the android applications (programs) on the smart phones. The Android application is handling transmission of ECG signals to the sending UWB module and then receiving them from the receiving UWB module as well as displaying them on the receiver. The future work to continue the present project is to replace the sending smart phone by an ECG device that sends real ECG signals.

Objectives: The inverse relationship between QT interval variability (QTV) and T wave amplitude potentially confounds QT variability assessment. We quantified the influence of the T wave amplitude on QTV in a comprehensive dataset and devised a correction formula. Methods: Three ECG datasets of healthy subjects were analyzed to model the relationship between T wave amplitude and QTV. To derive a generally valid correction formula, linear regression analysis was used. The proposed correction formula was applied to patients enrolled in the Evaluation of Defibrillator in Non-Ischemic Cardiomyopathy Treatment Evaluation trial (DEFINITE) to assess the prognostic significance of QTV for all-cause mortality in patients with non-ischemic dilated cardiomyopathy. Results: A strong inverse relationship between T wave amplitude and QTV was demonstrated, both in healthy subjects (R2 = 0.68, p < 0.001) and DEFINITE patients (R2 = 0.20, p < 0.001). Applying the T wave amplitude correction to QTV achieved 2.5-times better group discrimination between patients enrolled in the DEFINITE study and healthy subjects. Kaplan-Meier estimator analysis showed that T wave amplitude corrected QTVi is inversely related to survival (p < 0.01) and a significant predictor of all-cause mortality. Conclusion: We have proposed a simple correction formula for improved QTV assessment. Using this correction, predictive value of QTV for all-cause mortality in patients with non-ischemic cardiomyopathy has been demonstrated.

Abstract A cardiorespiratory system is highly regulated via the autonomic nervous system (ANS), whose function can be quantified noninvasively by analyzing electrocardiogram (ECG), blood pressure (BP) and respiration signals. Several conditions and illnesses are linked with imbalance of the ANS. This thesis aimed to develop methods for describing the ANS regulation of a cardiovascular system from short-term cardiorespiratory measurements. More specifically, the role of breathing rate and its effects on traditional frequency domain based cardiovascular indexes describing ANS control is addressed. The main contributions are as follows: 1) an adaptive filtering based method to remove respiratory influences from cardiovascular signals and indexes was developed. The adaptive filter reduced the bias caused by low respiration rate, enabling the usage of spontaneous respiration measurement protocol over controlled respiration. 2) Methods to quantify respiratory sinus arrhythmia (RSA) index from cardiovascular signals were developed as well: two methods utilizes adaptive filtering and either the measured respiration signal or the ECG-derived respiration signal and one method uses independent component analysis. Developed RSA index methods allow varying respiration rates making them physiologically more accurate than traditional high frequency power with fixed respiration rate, often used as RSA index. 3) Tools for studying the power and the frequency of low frequency (LF) oscillations of cardiovascular signals were developed, including a time-frequency representation for analyzing varying data. An experimental study was conducted with patients of continuum of cardiovascular risks. According to results, aging decreased the frequency of LF oscillation, whereas coronary artery disease decreased it further. 4) Two new ECG-derived respiration (EDR) methods utilizing decomposition techniques were developed. The proposed methods yielded statistically significant improvements over previously developed EDR methods. EDR method enables to get respiratory information from ECG, which in its turn reduces needed modalities in ANS quantification. This thesis provides methods to quantify indexes describing the ANS function more accurately by acknowledging the respiration effects. The results of this thesis may be utilized in various application areas, ranging from clinical to physiology research up to commercial health, wellness and sport products. / Tiivistelmä Autonominen hermosto säätelee tarkasti sydän- ja verenkiertoelimistöä sekä hengitystä. Autonomisen hermoston toimintaa voidaan analysoida laskennallisin menetelmin noninvasiivisesti mitatuista elektrokardiogrammi- (EKG, sydänsähkökäyrä), verenpaine- ja hengityssignaaleista. Useita tekijöitä ja sairauksia voidaan yhdistää autonomisen hermoston epätasapainoon. Väitöskirjassa kehitettiin menetelmiä sydän- ja verisuonijärjestelmän autonomisen säätelyn kuvaamiseksi lyhytaikaisista kardiorespiratorisista tallenteista. Erityistä huomiota on kiinnitetty hengityksen vaikutukseen perinteisiin taajuustasosta laskettaviin muuttujiin, jotka kuvaavat autonomisen hermoston toimintaa. Väitöskirjan päätuloksia ja -tuotoksia ovat: 1) uusi adaptiiviseen suodatukseen pohjautuva laskennallinen menetelmä hengitysvaikutuksien poistamiseksi sydän- ja verisuonisignaaleista. Adaptiivinen suodatin vähensi matalan hengitystaajuuden aiheuttamaa vääristymää hermoston toimintaa kuvaavista parametreistä. Uusi menetelmä mahdollistaa kontrolloimattoman eli vapaan hengitystaajuus-protokollan käytön autonomisen hermoston toiminnan mittauksissa. 2) Uusia menetelmiä respiratorisen sinus arrytmian (RSA) määrittämiseksi sydän- ja verisuonisignaaleista. Kehitetyissä menetelmistä kahdessa käytetään adaptiivista suodatusta hyödyntäen joko mitattua hengityssignaalia tai EKG:stä johdettua hengityssignaalia. Kolmas menetelmä pohjautuu itsenäisten komponenttien analyysiin. Kehitetyt menetelmät RSA:n laskemiseksi sallivat hengitystaajuuden vaihtelun mittauksien aikana, mikä tekee ne fysiologisesti tarkemmaksi kuin perinteisesti käytetty korkeataajuinen (HF) komponentti, joka lasketaan taajuustasossa tietyltä kaistalta riippumatta hengitystaajuudesta. 3) Kehitettiin ja sovellettiin menetelmiä EKG:n ja verenpaineen matalataajuisten (LF) heilahtelujen tutkimista varten. Yhdessä tutkimuksessa sovellettiin aika-taajuustason esitystapaa vaihtelevan datan analysoimiksi. Kokeellinen tutkimus tehtiin aineistolla, joka oli jatkumo sydän- ja verisuonitautien riskejä omaavista potilaista jo sairastuneisiin potilaisiin. Ikääntyminen pienensi matalataajuisen heilahtelun taajuutta ja sepelvaltimosairaus pienensi sitä edelleen. 4) Kaksi uutta hajotelmatekniikoita hyödyntävää menetelmää, joilla lasketaan EKG:stä hengitysvirtausignaali-estimaatti (EDR). Kehitettyjen EDR-menetelmien suorituskyky osoittautui tilastollisesti paremmaksi kuin aikaisemmat menetelmät. Koska hengityssignaali ja -taajuus voidaan johtaa suoraan EKG:stä, tarvittavien mittaussensoreiden määrää vähenee. Lisäksi EDR:ää voidaan hyödyttää autonomisen hermoston toimintaa kuvaavien parametrien estimoinnissa. Väitöskirja tarjoaa menetelmiä autonomisen hermoston toiminnan mittaamiseksi huomioiden erityisesti hengityksen vaikutus estimoitaviin parametreihin. Väitöskirjan tuloksia voidaan soveltaa useissa kardiorespiratorisia signaaleja hyödyntävissä sovelluksissa aina kliinisestä työstä fysiologian tutkimukseen ja kaupallisiin hyvinvointi-, terveys- ja urheilusovelluksiin. / Huomautus/Notice Painetussa virheellinen ISBN: 978-952-62-2312-4, oikea 978-952-62-2310-0. Printed version has incorrect ISBN: 978-952-62-2312-4, it should be 978-952-62-2310-0.

This semestral thesis deals with methods for continuous estimation of the quality of the ECG signal. The theoretical part includes the functional anatomy of the heart, the basics of electrocardiography, the types of noise that can be found in the ECG records, and a description of several methods for the continuous estimation of the ECG signal quality. Next here are some approaches to segmenting ECG signals based on their quality. The practical part deals with the implementation of two methods. The first method is the SNR estimation method based on the Wiener filter. The second method is the method of segmentation of ECG signals based on their quality. Both methods were tested on artificial and real signals.