The Thesis deals with the area of cardio stimulation. It describes the different stimulation modes and their specifics. It describes the creation of a virtual cardio stimulator based on R-waves, designed in the LabVIEW application. Part of the thesis is the software realization of the model and the verification of its functionality.

The intent of this thesis was to test if one of the many fitness-tracking devices, Microsoft’s Band 2 (MSB2), is accurate and reliable in detecting changes in Heart Rate (HR) and R-R intervals, during the repeated trial of two conditions of a working-memory test known as the N-Back. A 2 (devices: ECG, MSB2) × 4 (epochs: baseline 1, 1-back task, baseline 2, 3-back task) repeated measures factorial design was conducted. The participants were simultaneously equipped to the MSB2 and an electrocardiogram (ECG). The results of this study validated the MSB2 for the use in a cognitive task. The study suggests that fitness-tracking devices with similar sampling rates and features are candidates for further exploration as alternatives to ECG, in hope of making the inclusion of physiological data in psychological research more available and accessible. .

Abrupt decreases and increases in systolic arterial blood pressure produce baroreflex mediated shortening and lengthening, respectively, of the R-R interval. This phenomenon, otherwise known as the cardivagal baroreflex, is best described by the sigmoid relationship between R-R interval length and systolic blood pressure. The linear portion of this relationship is used to derive the slope or gain of the cardiovagal baroreflex. Importantly, lower levels of cardiovagal baroreflex have been associated with poor orthostatic tolerance and an increased cardiovascular disease-related mortality. The most commonly used and accepted technique to assess cardiovagal barorelex gain is the modified Oxford techinique. Bolus injections of sodium nitroprusside followed by phenylephrine HCL are used to decrease and raise blood pressure ~15 mmHg, respectively. The baroreflex control of the cardiac vagal outflow can then be assessed by the relation of the R-R interval to systolic blood pressure. However, the modified Oxford technique does not always reveal the nonlinear nature of baroreflex relations. The reasons for this has been unclear. Thus, analysis of baroreflex gain when nonlinearities are not revealed is problematic. Five classifications of baroreflex trials have been identified: acceptable, threshold-heavy, saturation-heavy, linear-heavy, and random trials. A new method of gain estimation was developed that combines the strengths of the current methods of gain estimation with the knowledge of the classifications of baroreflex trials. Using this method, cardiovagal baroreflex gain assessment can be maximized if threshold-heavy, saturation-heavy, and random trials are filtered out of the analysis and the manual method is used to estimate gain on the remaining trials. In addition, a link seems to exist between the variability of delta and the variability in baroreflex gain between different subjects. / Master of Science

This master´s thesis deals with the problem of heart stimulation by using external pacemaker. Such external pacemaker is used for a short – time stimulation of patient to overcome the time before the implantation of such apparatus. The master´s thesis informs about the basic function of heart and possible heart disorders which are treated by pacemaker. Great deal of master´s thesis is devoted to the design of external pacemaker wiring. This section describes the possibilities of controlling the pacemaker, circuits for detection R-R interval, a design of output circuit eith regard to required of stimulation and pacemaker feeding. The program Pspice was used to check the functional appropriateness of designed circuits and it was successively simulated in a non - soldering field.