No description available.

No description available.

Recent work has found that a frequency domain and time domain analysis of the heart rate variability signals can provide significant insights into function of the heart in healthy subjects and in patients with heart disease. Patients with congestive heart failure are an important clinical health issue and it is hoped that this work will contribute towards gaining knowledge of this debilitating pathological condition. Our laboratory has recently acquired more than three thousand 24-hour ECG tapes recorded during called Study of Left Ventricular Dysfunction (SOLVD). The SOL VD trial was conducted between 1987-1990 to test the efficacy of a medication called, Enalapril, to treat patients with heart failure. There were an equal number of patients with (group A) and without overt heart failure (group B). The work reported in this thesis describes the development of a hardware and software framework used to analyze the ECG signals recorded on these tapes. Primary objective of this work was to develop and test a system which would assist in analyzing the above tapes so as to examine if there are differences between two groups using the HRV parameters from both frequency and time domain. The research was conducted in three steps: Hardware design, software and algorithm development and finally the validation phase of the design, to test the usefulness of the overall system. The tapes were replayed on a tape recorder and the ECG was digitized at a rate corresponding to 500 samples/second. Labview software was invoked for this task. Secondly a set of algorithms were developed to perform QRS-detection and QT-interval identification. The detection algorithms involved placing critical ECG fiducials onto the ECG waveform through the use of a trained model. The model construction used patient specific pre-annotated data coupled with statistical and genetic algorithm techniques. The beat-to-beat HRV signal was thus generated using the annotation data from the ECG. Frequency domain indices were obtained using power spectral computation algorithms while time domain statistical indices were computed using standard methods. QT-interval algorithms were tested using a set of manually and automatically tagged set of beats from a sample of subjects. For the third part of this research, i.e. validation phase, we set up a test pool of 200 tapes each from patients with overt heart failure and with no heart failure, recorded at the baseline before the subjects entered the study. This phase of the study was conducted with the help of a statistician in a blinded fashion. Our results suggest that there is significant difference between frequency domain and time domain parameters computed from the HRV signals recorded from subjects belonging to group A and group B. The group A patients had a lot of ectopic beats and were challenging to analyze. These results provide a confirmation of our analytical procedures using real clinical data. The QT-analysis of the ECG signals suggest that automatic analysis of this interval is feasible using algorithms developed in this study. / Thesis / Master of Applied Science (MASc)

The purpose of this investigation was to examine the potential differences in autonomic nervous system adaptations, as assessed by heart rate variability techniques, between a group of stabilized CHF patients randomized to either a training group (aerobic+resistance) or a control group (usual care). In a single-blind, randomized controlled trial of 3-months of supervised exercise training and a further 3-months of home-based exercise, 28 stabilized CHF patients (NYHA 1-111) were randomized to either a training (AERWT) (n=16;11M,5F; age, 64.9±2.3; LVEF, 29.4±1.7%) or usual care (UC) (n=12; 10M,2F; age, 58.0±2.8; LVEF, 24.4±2.0%) group. Upon completion of the supervised exercise program, the AERWT group increased peak oxygen uptake (V02) (13.2±0.5 to 15.5±0.84 ml/kg/min, p<0.05), and single-arm curl scores (16.2±2.8 to 19.2±3.3 kg, p<0.05) significantly compared to the UC group, without any deleterious effect upon clinical status or left-ventricular function (LVEF: 31.3±1.7 to 33.2±1.9%, p=0.99). Physical training reduced expired ventilation and carbon dioxide based on successive workloads during symptom-limited incremental cycle ergometry in the AERWT group; however, this was found to be non-significant, in addition to changes in resting heart rate, anaerobic threshold, maximal exercise duration, maximal power output, and double product following training. Supine, resting power spectral indices remained unchanged from baseline to 6-months in both groups, as did the recovery of power spectral indices during supine rest following a symptom-limited incremental cycle ergometry test. A qualitative comparison of the power spectral changes from supine to standing revealed no significant differences between groups with respect to improvements in the baroreceptor response to orthostatic stress. Time domain parameters, derived from 24-hour ambulatory bolter monitoring, were also obtained at baseline, 3-months, and 6-months. The indices believed to be largely representative of vagal modulation, SDNN-Index, r-MSSD, and pNN50, tended to increase in the AERWT group with increased participation in the training program; however, the results did not obtain statistical significance (p=0.07). In addition, there were no significant changes in mean 24-hour heart rate or NN-interval, SDNN, or SDANN in the AERWT group (p=0.21). The present investigation revealed some evidence to suggest that exercise training in selected populations of CHF patients results in favourable changes in vagal modulation and baroreceptor sensitivity; however, unlike Coats et al. (1992), the present investigation failed to note any significant alterations in HRV frequency domain indices as a result of exercise training despite identical improvements in peak V02. The lack of significant findings in both the frequency and time domain HRV data could indicate that the autonomic dysfunction is so widespread and rampant in CHF that we cannot induce alterations through training as would be demonstrated in normal, healthy controls. In effect, these findings reinforce the hypothesis that in CHF the heart is the 'slave' of the periphery, and that due to the progressive lack of neural control of both the heart and circulation, in addition to an impairment in pump function, that the only effective means of improving physiological variables is through changes at the peripheral level. / Thesis / Master of Science (MS)

No description available.

Advances in technology are creating decreases in the number of premature deaths from cardiovascular disease, resulting in an increase in life expectancy. This decrease in mortality and increase in life expectancy has created an annual increase in the incidence of Congestive Heart Failure (CHF). Positive outcomes of adherence to recommendations for the treatment of CHF are documented in the literature. Recommendations focus on the reduction of symptoms, prevention of the progression of CHF, improved quality of life and the prevention of sudden death. The purpose of this study was to evaluate the degree of adherence and the differences in the adherence to Agency for Health Care Policy and Research practice guidelines between physicians caring for patients in the acute care setting and in the primary care setting as well as by specialty. This study identified significant differences in the assessment, diagnostic testing and medication regimen based on physician specialty as well as level of care. Education provided to patients diagnosed with CHF was found to be lacking in both the inpatient and outpatient setting and by physician specialties. Reinforcing and educating health care provides through evidence based practices will assist in the overall care of patients with CHF, decrease cost and improve the quality of life of those diagnosed with CHF.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 6 uppsatser.

Thesis (M.S.)--University of Michigan, 1998. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, 1998. / Includes bibliographical references.

Appendum consists of last two leaves. / Copies of author's previously published articles inserted. / Bibliography: leaves 241-283. / xviii, 284 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The studies described were designed to identify and address (through the application of relatively novel and potentially useful adjunctive therapeutic strategies) some of the determinants of sub-optimal therapeutic response in intermediate coronary syndrome and chronic congestive heart failure; especially when targeted towards those patients who fail to gain the maximal benefit from pre-existing modalities of pharmacological treatment. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1999