Application of the non-invasive methods to detection of the baroreflex sensitivity is a correct way to evaluate the functions of cardiovascular system. This master’s thesis describes the theoretical informations about the problem of baroreflex sensitivity from anatomical, patalogical and clinical views. Theoretical knowledges are foundation for mathematical description of some methods to detection of baroreflx sensitivity in time, frequency and information dimensions. In the practical part of the master’s theses are presented two methods of BRS detection – sequence method based on finding the specific sequences of time series signals and method of application bivariante autoregressive model. Both of methods are implemented in MATLAB. The results of testing data on real data are discussed.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to evaluate the effects of resistance training on blood pressure, ventricular repolarization, baroreflex sensitivity and cardiac autonomic balance in diabetic rats. Cardiovascular evaluation was performed in conscious trained and sedentary animals, 8 weeks after the onset of diabetes with alloxan or control animals. The resistance training consisted of 3 sets of 10 repetitions performed at 40% of one repetition maximum test, 3 days/wk over 8 wks in squattraining apparatus. Blood pressure was monitored for 30 min 48 h after the last training session or time control. Baroreflex sensitivity was analyzed by sequence method and cardiac autonomic balance was assessed by heart rate variability in the frequency domain. After 8 wks, the diabetes significantly increased glycemia (from 83 ± 8 to 381 ± 41 mg/dl, p<0.05), mean blood pressure (from 104.7 ± 5.4 to 125.1 ± 5.4 mmHg, p<0.05), QTc interval (from 4.4 ± 0.1 to 5.1 ± 0.1 ms, p<0.05), reduced baroreflex sensitivity (from 2.01 ± 0.3 to 0.38 ± 0.1 ms/mmHg, p<0.05) and impaired the cardiac autonomic balance. Resistance training was able to produce significant reduction on the glycemia (270 ± 17 mg/dl, p<0.05), prevented the increase of mean blood pressure (108 ± 3 mmHg, p<0.001) and QTc interval (4.6 ± 0.1 ms, p<0.01), the reduction of baroreflex sensitivity (2.63 ± 0.5 ms/mmHg, p<0.01) and disturbance on the cardiac autonomic balance. These results suggest that resistance training promotes a better glycemic control, prevents hypertension and improves baroreflex sensitivity and cardiac autonomic balance in alloxan diabetic rats. / O objetivo desse estudo foi avaliar os efeitos do treinamento físico resistido sobre a pressão arterial, repolarização ventricular, sensibilidade barorreflexa e balanço autonômico cardíaco em ratos diabéticos. A avaliação cardiovascular foi realizada em animais conscientes treinados e sedentários, após 8 semanas do início do diabetes com aloxana ou nos animais controle. O treinamento físico resistido consistiu de 3 séries de 10 repetições realizada a 40% do teste de uma repetição máxima, 3 dias/semana durante 8 semanas em um aparato que simula o exercício de agachamento em humanos. Pressão arterial foi monitorada por 30 minutos 48 horas após a última sessão de treinamento físico ou tempo controle. A sensibilidade barorreflexa foi analisada pelo método da sequência e o balanço autonômico cardíaco foi avaliado pela variabilidade da freqüência cardíaca no domínio da freqüência. Após 8 semanas, o diabetes aumentou significativamente a glicemia (de 83 ± 8 para 381 ± 41 mg/dl), pressão arterial média (de 104.7 ± 5,4 para 125 ± 5,4 mmHg), intervalo QTc (de 4,4 ± 0,1 para 5,1 ± 0,1 ms), reduziu sensibilidade barorreflexa (de 2,01 ± 0,3 para 0,38 ± 0,1 ms/mmHg) e produziu um distúrbio sobre o balanço autonômico cardíaco. O treinamento físico resistido foi capaz de produzir significante redução sobre a glicemia (270 ± 17 mg/dl), preveniu o aumento da pressão arterial (100,8 ± 4,2 mmHg) e intervalo QTc (4,6 ± 0,1 ms), a redução da sensibilidade barorreflexa (2,63 ± 0,5 ms/mmHg) e distúrbio sobre a balanço autonômico cardíaco. Esses resultados sugerem que o treinamento físico resistido promove um melhor controle glicêmico, previne hipertensão e melhora a sensibilidade barorreflexa e balanço autonômico cardíaco em ratos diabéticos induzidos pela aloxana.

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No. of bitstreams: 2 Dissertação - Paulo Ricardo Lopes - 2016.pdf: 2527279 bytes, checksum: 8fddf73d441c79ccd59737e173e34303 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-11 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Physical training has been cited as an effective non-pharmacological treatment in the control of metabolic syndrome and cardiovascular diseases. In addition, the diminazene aceturate (DIZE) is a potential therapeutic tool which enhances the catalytic effect of ACE2 of the renin-angiotensin system and, as a final product, can increase the concentrations of angiotensin (1-7). In turn, angiotensin (1-7) is able to interact with MAS receptor and promote opposite effects to the vasoconstrictor, proliferative and hypertrophic axis of ANG II (ACE-ANG II AT1-) promoting vasodilator, antiproliferative and anti-hypertrophic effects. However, little is known about the association between exercise and antihypertensive drugs. This study sought to determine the effects of aerobic training on a treadmill associated with DIZE administration on cardiovascular parameters in spontaneously hypertensive rats (SHR). Therefore, SHR rats at 12 weeks of age were used. One group was underwent to eight weeks of training on a treadmill (T). Another group remained without physical activity (S). On the last 15 days of training, the animals were redistributed into four groups: S and T animals receiving DIZE (1 mg / kg, i.g.; D1) or distilled water (vehicle; V) by gavage. Tail plethysmography was performed throughout the treatment. At the end of the treatment, the animals were anesthetized 2-3% halotana (Cristália Ltda, Brazil) and surgery cannulation (femoral artery and vein) and implant ECG electrode were performed. After 24 hours, the animals were subjected to the PAP, MAP, ECG and HR records before and after pharmacological stimulation to obtain the baroreflex index (BI; Phenylephrine 2 mg / kg) and double autonomic blockade (Atropine 4 mg / kg; metoprolol 2 mg / kg). We observed that aerobic training is not effective in causing hypotension in the trained animals (T, from 196.3 ± 3.0 to 198.7 mm Hg ± 2.3 mm Hg; Figure 5A) compared to sedentary group (S: from 195.9 ± 3.2 to 197.5 ± 4.6 mm Hg; Figure 5A). However, we can observe bradycardia in the trained group compared to the sedentary group, since the first two weeks (T: n = 15, 370.2 ± 4.7 vs. S: n = 15, 388.1 ± 5.1 bpm; p <0.05) until the end of the training (T: 367.0 ± 3.8 vs. S: 395.8 ± 6.1 mmHg, p <0.05). In all, after treatment with DIZE it was observed a decrease in the SBP of the trained group that received DIZE in relation to the trained group receiving vehicle (T + D1 n = 6 186.4 ± 5.5 vs. T + V n = 9 199.4 ± 4.2 mmHg, p <0.05). However, there was no significant difference between both groups sedentary (S + V: n = 8, 198.2 ± 4.9 vs. S + D1: n = 7, 185.0 ± 6.0 mmHg) and, between sedentary and trained groups that received treatment with DIZE (S + D1: 185.0 ± 6.0 vs. T D1 +: 186.4 ± 5.5 mmHg). Moreover, we observed reduction in SBP of the trained group that received DIZE against the trained group receiving vehicle (T + D1: n = 6, 186.4 ± 5.5 vs. T + V: n = 9, 199.4 ± 4.2 mmHg, p <0.05). However, there was no significant difference in this parameter between both sedentary groups (S + V: n = 8, 198.2 ± 4.9 vs. S + D1: n = 7, 185.0 ± 6.0 mmHg). It was evidenced improvement of IB in T + D1 animals (-1.15 ± 0.16 02 bpm / mmHg, p <0.05) when compared to other groups (S + V: -0.70 ± 0.03; S + D1: -0.77 ± 0.02; T + V: -0.98 ± 0.02 bpm / mm Hg). We also observed an reduction in IHR rats T + D1 (bpm 334.8 ± 4.8; p <0.05) compared with T + V (353.5 ± 7.4 beats per minute) or S + D1 (353.7 ± 7.4 beats per minute) groups. Together the results demonstrate that physical exercise on a treadmill was effective in promoting rest bradycardia. Furthermore the association of physical training and DIZE potentiate bradycardia, reduced SBP and intrinsic HR and even improved baroreflex sensitivity in SHR. Finally, it is concluded that the association of physical activity with the activator of angiotensin-converting enzyme 2 improves the cardiovascular system in SHR. / O treinamento físico tem sido apontado como um tratamento não farmacológico coadjuvante no controle de doenças cardiovasculares, dentre as quais destacamos a Hipertensão Arterial. Por outro lado, o aceturato de diminazeno (DIZE) é um fármaco capaz de potencializar o efeito catalítico da enzima conversora de angiotensina 2 (ECA2) do sistema renina-angiotensina e como produto final aumentar as concentrações de Angiotensina (1-7) (ANG (1-7)). Por sua vez, a ANG (1-7) é capaz de interagir com receptor MAS promovendo efeitos vasodilatador, antiproliferativo e anti-hipertrófico. Entretanto, pouco se sabe sobre a associação entre exercício físico e fármacos anti-hipertensivos. O presente estudo procurou determinar os efeitos do treinamento aeróbico em esteira rolante associada à administração de DIZE sobre parâmetros cardiovasculares em ratos espontaneamente hipertensos (SHR). Para tanto, foram utilizados machos SHR com 12 semanas de idade. Um grupo foi submetido a oito semanas de treinamento em esteira (T). Outro grupo permaneceu sem atividade física (S). Nos últimos 15 dias de treinamento, os animais foram redistribuídos em quatro grupos, onde animais S e T receberam Dize (1 mg / kg; i.g.; D1) ou água destilada (veículo; V) por gavagem. Foi realizada pletismografia de cauda durante todo tratamento. Ao final do tratamento, os animais foram anestesiados com halotana 2-3% (Cristália Ltda, Brasil) e submetidos à cirurgia de canulação (artéria e veia femorais) e implante de eletrodo de eletrocardiograma (ECG). Após 24 horas, os animais foram submetidos ao registro de pressão arterial pulsátil (PAP), pressão arterial média (PAM), ECG e frequência cardíaca (FC) antes e após estimulação farmacológica para obtenção do índice baroreflexo (IB; Fenilefrina 2 μg / Kg) e duplo bloqueio autonômico (Atropina 4 mg / Kg; Metropolol 2 mg / Kg). Por fim, os animais foram eutanasiados e decapitados para a extração do coração. Observamos que o treinamento aeróbio não foi eficaz em promover hipotensão nos animais treinados (T; de 196,3 ± 3,0 mm Hg para 198,7 ± 2,3 mm Hg; Figura 5A) em comparação com o grupo sedentário (S: de 195,9 ± 3,2 para 197,5 ± 4,6 mm Hg; Figura 5A). Entretanto, podemos observar bradicardia no grupo treinado em relação ao grupo sedentário, desde as duas primeiras semanas (T: n=15, 370,2 ± 4,7 vs. S: n=15, 388,1 ± 5,1 bpm; p<0,05) até o termino do treinamento (T: 367,0 ± 3,8 vs. S: 395,8 ± 6,1 mmHg; p<0,05). Além disso, observamos redução dos valores de PAS do grupo treinado que recebeu DIZE em relação ao grupo treinado que recebeu veículo (T+D1: n=6, 186,4 ± 5,5 vs. T+V: n=9, 199,4 ± 4,2 mmHg; p<0,05). Entretanto, não houve diferença significativa desse parâmetro entre ambos os grupos sedentários (S+V: n=8, 198,2 ± 4,9 vs. S+D1: n=7, 185,0 ± 6,0 mmHg). Evidenciamos também redução do IB de ratos T+D1 (-1,15 ± 0,16 02 bpm /mmHg; p<0,05) quando comparados aos demais grupos (S+V: -0,70 ± 0,03; S+D1: -0,77 ± 0,02; T+V: -0,98 ± 0,02 bpm / mmHg). Observamos ainda uma redução da FC intrínseca dos ratos T+D1 (334,8 ± 4,8 bpm; p<0,05) quando comparados com os ratos T+V (353,5 ± 7,4 bpm) ou com os ratos S+D1 (353,7 ± 7,4 bpm). Em conjunto os resultados apresentados demonstram que o exercício físico em esteira foi efetivo em promover bradicardia de repouso. Ademais a associação do treinamento com o DIZE potencializou a bradicardia, reduziu a PAS e a FC intrínseca e ainda melhorou a sensibilidade baroreflexa em SHR. Por fim, conclui-se que a associação do exercício físico com o ativador da enzima conversora de angiotensina 2 melhora o sistema cardiovascular em SHR.

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.

A síncope neurocardiogênica (SNC) é caracterizada por perda transitória da consciência e do controle postural, devido a uma hipoperfusão cerebral global de surgimento abrupto, com recuperação rápida e espontânea do paciente ao retornar à posição horizontal. Entretanto, investigações adicionais são necessárias para melhor avaliação das respostas cardiorrespiratórias e autonômicas de pacientes com SNC submetidos ao Tilt-test. O presente estudo teve como objetivo avaliar, em pacientes com história clínica sugestiva de SNC, os efeitos da mudança postural induzidas pelo Tilt-test na pressão arterial (PA) e frequência cardíaca (FC), na variabilidade cardiocirculatória e na sensibilidade barorreflexa (SBR). Além disso, o estudo também avaliou a relação entre a idade, sexo e características antropométricas dos pacientes com as respostas ao Tilt-test, e a relação entre o tempo do início da mudança postural e o momento da síncope, com um ou mais parâmetros acima mencionados. O estudo foi dividido em 3 partes: 1 Estudo retrospectivo de 180 pacientes, com história clínica sugestiva de SNC, mas que apresentaram Tilt-test positivo (TTP) (128 indivíduos) ou negativo (TTN) (52 indivíduos) para síncope; 2 Estudo da variabilidade da frequência cardíaca (VFC), usando-se métodos lineares (Transformada Rápida de Fourier) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram incluídos 62 pacientes, 31 com Tilt-test positivo e 31 negativo; 3 Estudo da variabilidade da pressão arterial sistólica (VPAS), usando-se métodos lineares (Transformada Rápida de Fourier), e da SBR (Método da Sequência) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram estudados 33 indivíduos, 16 com Tilt-test positivo e 17 negativo. Estudo 1 Observou-se que a incidência de SNC foi 1,5 vezes maior em mulheres do que em homens. Além disso, os grupos TTP e TTN apresentaram idade e características antropométricas semelhantes entre si, e não houve significância estatística nas correlações entre o tempo do início da posição vertical até a síncope, a idade e as características antropométricas. Estudo 2 Comparando os 2 grupos nos domínios do tempo (SD-iRR, variância-iRR, RMSSD) e da frequência (LF (un), HF (un) e LF/HF) nas fases Pré-Tilt, Tilt e Pós-Tilt, com exceção do iRR (ms), não observou-se diferença entre os grupos. Houve, na fase Tilt, um menor valor do iRR no grupo TTP. O Pré-Tilt comparado ao Tilt, promoveu em ambos os grupos redução do iRR e aumento na razão LF/HF. Estudo 3 Comparando-se os grupos TTP e TTN no Pré-Tilt e Tilt, não houve diferença no LF da PAS e na SBR. O Tilt promoveu, em ambos os grupos, aumento no LF da PAS, redução na SBR. Somente no grupo TTP foi observado aumento no desvio padrão da PAS durante o Tilt. Em conclusão, o estudo 1 demonstrou que a SNC não foi influenciada pela idade e características antropométricas, no que diz respeito à prevalência, e ao tempo de duração entre o início da mudança postural no Tilt-test e o momento do aparecimento da síncope na posição vertical. O estudo 2 demonstrou que indivíduos com suspeita clínica de SNC, e Tilt-test positivo ou negativo não apresentam anormalidades no balanço simpato-vagal cardíaco, mas, apresentaram diferenças no iRR. O estudo 3 não evidenciou diferenças no controle autonômico cardiovascular (LF-PAS e SBR) entre os grupos TTP e TTN no Pré-Tilt e Tilt. Os estudos 2 e 3 mostraram que com a metodologia utilizada na análise da VFC e VPAS não foi possível detectar anormalidades significativas da modulação autonômica cardiovascular nos grupos TTP e TTN, e desse modo, prever na posição vertical do Tilttest, se um paciente com história clínica sugestiva de SNC apresentará ou não síncope. / Neurocardiogenic syncope (NCS) is characterized by transient loss of consciousness and postural control, due to abrupt global cerebral hypoperfusion, with rapid and spontaneous recovery after changing the patient to horizontal position. However, further investigations are necessary to better understand the cardiorespiratory and autonomic responses to the Tilt-test in NCS patients. The present study aimed to evaluate, in patients with a history suspicion of NCS, the effects of postural change (Tilt-test) on blood pressure (BP) and heart rate (HR), on the cardiovascular variability and baroreflex sensitivity (BRS). Furthermore, the study also assessed the relationship between age, sex and anthropometric characteristics with the Tilt-test responses, and the relationship between the time period taken to experience syncope following postural change and the above cited parameters. The study was divided into three parts: 1 A retrospective study with 180 patients with a history suspicion of NCS, that experienced (TTP; 128 individuals) or not (TTN; 52 individuals) syncope following Tilt-test; 2 A study of the heart rate variability (HRV), assessed by linear methods (Fast Fourier Transform), in patients with a history suspicion of NCS and that experienced, or not, syncope following Tilt-test. The study included 62 patients (31 in TTP group and 31 in TTN group); 3 A study of the systolic blood pressure variability (SAPV), using linear methods (Fast Fourier Transform), and of the BRS (Sequence Method) in patients with a history compatible with NCS and that experienced, or not, syncope following Tilt-test. The study included 33 patients (16 in TTP group and 17 in TTN group). Study 1 it was observed that the incidence of NCS was 1.5 times greater in women than in men. Furthermore, groups TTP and TTN showed age and anthropometric characteristics similar to each other and no statistical significance was observed in the correlations among the time period taken to experience syncope following postural change and age and anthropometric characteristics. Study 2 The analysis of the cardiovascular variability, by means of time (SD-iRR, variance-iRR, RMSSD) and frequency (LF (nu), HF (nu) and LF/HF) domain methods, revealed no differences between groups in the Pre-Tilt, Tilt and Post-Tilt phases. However, iRR (ms) was found different between groups. During the Tilt phase, TTP group has shown lower iRR as compared to TTN. Also, TTP and TTN groups exhibited lower iRR and higher LF/HF ratio during Tilt-test as compared to Pre-Tilt phase. Study 3 Comparing the TTP and TTN groups, no statistical differences were found in the LF power of SAP and BRS in both Pre-Tilt and Tilt phases. Following Tilt-test it was observed an increase in LF power of SAP and a reduction in BRS. TTP group showed higher SAP standard deviation during the Tilt phase. In conclusion, study 1 demonstrated that NCS incidence and the time period taken to experience syncope following postural change were not influenced by age and anthropometric characteristics. Study 2 has shown that patients with a history suspicion of NCS, that experienced or not syncope following Tilt-test do not show abnormalities in the sympatovagal balance, but exhibited changes in the iRR. Study 3 showed that the cardiovascular autonomic control (LF-SAP and BRS) is not different between the TTP and TTN groups, in the Pre-Tilt and Tilt phases. Studies 2 and 3 have shown that the methods employed in the analysis of HRV and SAPV were unable to reveal abnormalities in the cardiovascular autonomic modulation in TTP and TTN groups, and thus, can not predict if a patient with a history suspicion of NCS will experience or not syncope during Tilt-test.

Hintergrund: Die chronisch obstruktive Lungenerkrankung (COPD) ist eine der Haupttodesursachen weltweit. Eine gesteigerte Aktivität des sympathischen Nervensystems wird als wesentlicher pathophysiologischer Aspekt vermutet. Grundsätze: Die vorliegende Arbeit untersuchte die muskelsympathische Nervenaktivität (MSNA) und die Baroreflex-Sensitivität bei COPD-Patienten und gesunden Probanden in Ruhe sowie unter moderater körperlicher Belastung. Ergebnisse: COPD-Patienten zeigten in Ruhe eine signifikant gesteigerte MSNA sowie eine signifikant verminderte Baroreflex-Sensitivität. Diese Ergebnisse bestätigen die Resultate vorausgegangener Publikationen der Arbeitsgruppe. In der vorliegenden Arbeit konnte erstmals ein signifikanter Anstieg der MSNA unter moderater statischer Belastung bei COPD-Patienten nachgewiesen werden. Fazit: In der vorliegenden Arbeit konnte erstmals eine Korrelation zwischen sympatho-vagaler Imbalance und verminderter körperlicher Leistungsfähigkeit bei COPD-Patienten nachgewiesen werden. Eine Modifikation der neuro-humoralen Aktivität bei COPD-Patienten könnte in Zukunft eine Rolle in der Behandlung der COPD spielen und sollte in größeren, randomisierten Studien untersucht werden.

Objective: As the multiple trigonometric regressive spectral (MTRS) analysis is extraordinary in its ability to analyze short local data segments down to 12 s, we wanted to evaluate the impact of the data segment settings by applying the technique of MTRS analysis for baroreflex sensitivity (BRS) estimation using a standardized data pool. Methods: Spectral and baroreflex analyses were performed on the EuroBaVar dataset (42 recordings, including lying and standing positions). For this analysis, the technique of MTRS was used. We used different global and local data segment lengths, and chose the global data segments from different positions. Three global data segments of 1 and 2 min and three local data segments of 12, 20, and 30 s were used in MTRS analysis for BRS. Results: All the BRS-values calculated on the three global data segments were highly correlated, both in the supine and standing positions; the different global data segments provided similar BRS estimations. When using different local data segments, all the BRS-values were also highly correlated. However, in the supine position, using short local data segments of 12 s overestimated BRS compared with those using 20 and 30 s. In the standing position, the BRS estimations using different local data segments were comparable. There was no proportional bias for the comparisons between different BRS estimations. Conclusion: We demonstrate that BRS estimation by the MTRS technique is stable when using different global data segments, and MTRS is extraordinary in its ability to evaluate BRS in even short local data segments (20 and 30 s). Because of the non-stationary character of most biosignals, the MTRS technique would be preferable for BRS analysis especially in conditions when only short stationary data segments are available or when dynamic changes of BRS should be monitored.

A síncope neurocardiogênica (SNC) é caracterizada por perda transitória da consciência e do controle postural, devido a uma hipoperfusão cerebral global de surgimento abrupto, com recuperação rápida e espontânea do paciente ao retornar à posição horizontal. Entretanto, investigações adicionais são necessárias para melhor avaliação das respostas cardiorrespiratórias e autonômicas de pacientes com SNC submetidos ao Tilt-test. O presente estudo teve como objetivo avaliar, em pacientes com história clínica sugestiva de SNC, os efeitos da mudança postural induzidas pelo Tilt-test na pressão arterial (PA) e frequência cardíaca (FC), na variabilidade cardiocirculatória e na sensibilidade barorreflexa (SBR). Além disso, o estudo também avaliou a relação entre a idade, sexo e características antropométricas dos pacientes com as respostas ao Tilt-test, e a relação entre o tempo do início da mudança postural e o momento da síncope, com um ou mais parâmetros acima mencionados. O estudo foi dividido em 3 partes: 1 Estudo retrospectivo de 180 pacientes, com história clínica sugestiva de SNC, mas que apresentaram Tilt-test positivo (TTP) (128 indivíduos) ou negativo (TTN) (52 indivíduos) para síncope; 2 Estudo da variabilidade da frequência cardíaca (VFC), usando-se métodos lineares (Transformada Rápida de Fourier) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram incluídos 62 pacientes, 31 com Tilt-test positivo e 31 negativo; 3 Estudo da variabilidade da pressão arterial sistólica (VPAS), usando-se métodos lineares (Transformada Rápida de Fourier), e da SBR (Método da Sequência) em pacientes com história clínica sugestiva de SNC, e com respostas positiva ou negativa ao Tilt-test. Foram estudados 33 indivíduos, 16 com Tilt-test positivo e 17 negativo. Estudo 1 Observou-se que a incidência de SNC foi 1,5 vezes maior em mulheres do que em homens. Além disso, os grupos TTP e TTN apresentaram idade e características antropométricas semelhantes entre si, e não houve significância estatística nas correlações entre o tempo do início da posição vertical até a síncope, a idade e as características antropométricas. Estudo 2 Comparando os 2 grupos nos domínios do tempo (SD-iRR, variância-iRR, RMSSD) e da frequência (LF (un), HF (un) e LF/HF) nas fases Pré-Tilt, Tilt e Pós-Tilt, com exceção do iRR (ms), não observou-se diferença entre os grupos. Houve, na fase Tilt, um menor valor do iRR no grupo TTP. O Pré-Tilt comparado ao Tilt, promoveu em ambos os grupos redução do iRR e aumento na razão LF/HF. Estudo 3 Comparando-se os grupos TTP e TTN no Pré-Tilt e Tilt, não houve diferença no LF da PAS e na SBR. O Tilt promoveu, em ambos os grupos, aumento no LF da PAS, redução na SBR. Somente no grupo TTP foi observado aumento no desvio padrão da PAS durante o Tilt. Em conclusão, o estudo 1 demonstrou que a SNC não foi influenciada pela idade e características antropométricas, no que diz respeito à prevalência, e ao tempo de duração entre o início da mudança postural no Tilt-test e o momento do aparecimento da síncope na posição vertical. O estudo 2 demonstrou que indivíduos com suspeita clínica de SNC, e Tilt-test positivo ou negativo não apresentam anormalidades no balanço simpato-vagal cardíaco, mas, apresentaram diferenças no iRR. O estudo 3 não evidenciou diferenças no controle autonômico cardiovascular (LF-PAS e SBR) entre os grupos TTP e TTN no Pré-Tilt e Tilt. Os estudos 2 e 3 mostraram que com a metodologia utilizada na análise da VFC e VPAS não foi possível detectar anormalidades significativas da modulação autonômica cardiovascular nos grupos TTP e TTN, e desse modo, prever na posição vertical do Tilttest, se um paciente com história clínica sugestiva de SNC apresentará ou não síncope. / Neurocardiogenic syncope (NCS) is characterized by transient loss of consciousness and postural control, due to abrupt global cerebral hypoperfusion, with rapid and spontaneous recovery after changing the patient to horizontal position. However, further investigations are necessary to better understand the cardiorespiratory and autonomic responses to the Tilt-test in NCS patients. The present study aimed to evaluate, in patients with a history suspicion of NCS, the effects of postural change (Tilt-test) on blood pressure (BP) and heart rate (HR), on the cardiovascular variability and baroreflex sensitivity (BRS). Furthermore, the study also assessed the relationship between age, sex and anthropometric characteristics with the Tilt-test responses, and the relationship between the time period taken to experience syncope following postural change and the above cited parameters. The study was divided into three parts: 1 A retrospective study with 180 patients with a history suspicion of NCS, that experienced (TTP; 128 individuals) or not (TTN; 52 individuals) syncope following Tilt-test; 2 A study of the heart rate variability (HRV), assessed by linear methods (Fast Fourier Transform), in patients with a history suspicion of NCS and that experienced, or not, syncope following Tilt-test. The study included 62 patients (31 in TTP group and 31 in TTN group); 3 A study of the systolic blood pressure variability (SAPV), using linear methods (Fast Fourier Transform), and of the BRS (Sequence Method) in patients with a history compatible with NCS and that experienced, or not, syncope following Tilt-test. The study included 33 patients (16 in TTP group and 17 in TTN group). Study 1 it was observed that the incidence of NCS was 1.5 times greater in women than in men. Furthermore, groups TTP and TTN showed age and anthropometric characteristics similar to each other and no statistical significance was observed in the correlations among the time period taken to experience syncope following postural change and age and anthropometric characteristics. Study 2 The analysis of the cardiovascular variability, by means of time (SD-iRR, variance-iRR, RMSSD) and frequency (LF (nu), HF (nu) and LF/HF) domain methods, revealed no differences between groups in the Pre-Tilt, Tilt and Post-Tilt phases. However, iRR (ms) was found different between groups. During the Tilt phase, TTP group has shown lower iRR as compared to TTN. Also, TTP and TTN groups exhibited lower iRR and higher LF/HF ratio during Tilt-test as compared to Pre-Tilt phase. Study 3 Comparing the TTP and TTN groups, no statistical differences were found in the LF power of SAP and BRS in both Pre-Tilt and Tilt phases. Following Tilt-test it was observed an increase in LF power of SAP and a reduction in BRS. TTP group showed higher SAP standard deviation during the Tilt phase. In conclusion, study 1 demonstrated that NCS incidence and the time period taken to experience syncope following postural change were not influenced by age and anthropometric characteristics. Study 2 has shown that patients with a history suspicion of NCS, that experienced or not syncope following Tilt-test do not show abnormalities in the sympatovagal balance, but exhibited changes in the iRR. Study 3 showed that the cardiovascular autonomic control (LF-SAP and BRS) is not different between the TTP and TTN groups, in the Pre-Tilt and Tilt phases. Studies 2 and 3 have shown that the methods employed in the analysis of HRV and SAPV were unable to reveal abnormalities in the cardiovascular autonomic modulation in TTP and TTN groups, and thus, can not predict if a patient with a history suspicion of NCS will experience or not syncope during Tilt-test.

Objective: As the multiple trigonometric regressive spectral (MTRS) analysis is extraordinary in its ability to analyze short local data segments down to 12 s, we wanted to evaluate the impact of the data segment settings by applying the technique of MTRS analysis for baroreflex sensitivity (BRS) estimation using a standardized data pool. Methods: Spectral and baroreflex analyses were performed on the EuroBaVar dataset (42 recordings, including lying and standing positions). For this analysis, the technique of MTRS was used. We used different global and local data segment lengths, and chose the global data segments from different positions. Three global data segments of 1 and 2 min and three local data segments of 12, 20, and 30 s were used in MTRS analysis for BRS. Results: All the BRS-values calculated on the three global data segments were highly correlated, both in the supine and standing positions; the different global data segments provided similar BRS estimations. When using different local data segments, all the BRS-values were also highly correlated. However, in the supine position, using short local data segments of 12 s overestimated BRS compared with those using 20 and 30 s. In the standing position, the BRS estimations using different local data segments were comparable. There was no proportional bias for the comparisons between different BRS estimations. Conclusion: We demonstrate that BRS estimation by the MTRS technique is stable when using different global data segments, and MTRS is extraordinary in its ability to evaluate BRS in even short local data segments (20 and 30 s). Because of the non-stationary character of most biosignals, the MTRS technique would be preferable for BRS analysis especially in conditions when only short stationary data segments are available or when dynamic changes of BRS should be monitored.

This Master's thesis deals with the influence of breathe to baroreceptor reflex. The first chapter is focused on measuring of blood pressure, in reference to later used method. In the second part is detailed analysis and explanation of term baroreflex, relationship between frequency spectra of systolic blood pressure, heart rate and breathing, mechanisms of regulation of blood pressure and heart rate variability. Third chapter deals with possible ways, how to analyze data, which are needed for estimation of baroreflex sensitivity, analyze of heart rate variability and estimation of power spectral density. Next parts of this thesis is paid attention to technical equipment and methods of acqusition of data, using this equipmnent. Part of this work is also software application, which makes possible from the recorded data estimate baroreflex sensitivity.