Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) is a breathing disorder characterized by recurrent episodes of upper airway collapse during sleep. Measuring cardiac function in OSAHS patients may provide information to help delineate not only chronic effects of autonomic imbalance and ventricular loading in the diseases state, but also possible beneficial effects of clinical treatments. Objectives (Study 1): The aim of this study was to determine the reproducibility of select cardiac variables when monitoring a simulated sleep apnea event using a new improved bioimpedance cardiography system. Methods: Fifteen apparently healthy males were tested on three different days in a protocol requiring their performance of two 15 sec and two 30 sec forced and sustained inspiratory efforts against a closed epiglottis (Müeller Maneuver-MM). Results: Changes in cardiac output (CO), heart rate (HR), stroke volume (SV), myocardial contractility index (MCI) and systemic vascular resistance (SVR) were similar during 15 sec and 30 sec MM in all three days. During 30 sec MM, these changes in cardiac function were pronounced in comparison to the minimal variations observed for the 15 sec MM challenge test. Objectives (Study 2): The aim of this study was to characterize the cardiac responses to negative intrathoracic pressure in OSAHS patients with and without hypertension versus healthy subjects. Methods: Two groups of 10 OSAHS patients, one without HTN and one with HTN were compared with a control group. Each subject underwent two 30 sec (MM) as previously described. Results: During MM, there were similar changes in SV, HR and SVR in all three groups. CO was lower during MM in controls compared to OSAHS groups, whereas MCI decreased during MM in both controls and OSAHS+HTN groups (-7.5% and -1.7%, respectively) compared with an increase in OSAHS group (11.8%). During a Post-MM, both OSAHS groups showed return of cardiac responses toward their pre-MM baseline within 30 sec. Conclusions: The new bioimpedance cardiograph evaluated in this study was found to be reliable for measuring acute changes in cardiac responses to this breathing challenge test. OSAHS may cause acute changes in selected cardiac parameters during and immediately after a breathing challenge test. / Ph. D.

Made available in DSpace on 2015-07-22T20:50:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-11-25. Added 1 bitstream(s) on 2015-08-11T03:25:54Z : No. of bitstreams: 1 Publico-11760a.pdf: 1069601 bytes, checksum: 88c7a2d10e394e1888e3b93a69070de4 (MD5). Added 1 bitstream(s) on 2015-08-11T03:25:54Z : No. of bitstreams: 2 Publico-11760a.pdf: 1069601 bytes, checksum: 88c7a2d10e394e1888e3b93a69070de4 (MD5) Publico-11760b.pdf: 1959621 bytes, checksum: 2665d88fb8fec237d73fdc84aa78a26a (MD5) / Introdução: A insuficiência cardíaca congestiva (ICC) descompensada pode ser definida como a evidência de sinais e sintomas de insuficiência cardíaca (IC) ao repouso e representa estado de ativação neuro-hormonal intensa, secundária ao déficit de perfusão renal. Regurgitações valvares funcional mitral e tricúspide são causas reversíveis de diminuição de fluxo sanguíneo sistêmico eficaz. O impacto de tais regurgitações sobre o débito cardíaco, sobre o conteúdo de fluido torácico, sobre as dimensões de câmaras cardíacas e sobre a função do aparato valvular pode ser monitorado de forma não-invasiva, antes e após a otimização do tratamento clínico. Objetivo: Avaliar o papel das regurgitações valvares funcional mitral e tricúspide como causas reversíveis de redução do débito cardíaco em ICC descompensada, e que acompanham a disfunção ventricular sistólica em miocardiopatias isquêmica e não-isquêmica. Métodos: catorze pacientes do sexo masculino (66 ± 8 anos de idade), fração de ejeção (24 ± 5%) secundária às miocardiopatias isquêmica (71%) e não-isquêmica (29%), apresentaram ICC descompensada com evidência clínica de regurgitações valvares mitral e tricúspide, foram avaliados por Bioimpedância cardíaca e ecocardiografia antes e uma semana após otimização de tratamento clínico. Resultados: o tratamento farmacológico de ICC descompensada foi acompanhado de redução de peso corpóreo de 82,9 a 76 kg (P<0,01), elevação no índice cardíaco (de 2,1 para 2,6 L/min/m2; P<0,01), redução na pressão sistólica da artéria pulmonar (de 58 para 35 mm Hg; P<0,001), conteúdo de fluido torácico (de 39 para 32 kOhm; P<0,001) e resistência vascular sistêmica (de 1633 para 1209 dinas/seg/cm5; P<0.001). A melhora dessas regurgitações incluiu redução nas dimensões das câmaras atriais esquerda e direita (de 27 para 24 cm2 e de 26 para 23 cm2, respectivamente; (P<0,001), diminuição das regurgitações mitral e tricúspide detectadas pelo Doppler colorido (P < 0,01), do volume regurgitante mitral (de 105 para 65 ml; P<0,001), e do tamanho efetivo do orifício regurgitante mitral (de 0,8 para 0,6 cm2; P<0,01). Conclusões: Na ICC descompensada, as regurgitações funcionais mitral e tricúspide contribuem para redução do débito cardíaco, aumento do conteúdo fluido torácico e da resistência vascular sistêmica, simultaneamente ao aumento de câmaras atriais e do orifício valvar, os quais podem ser melhorados com tratamento clínico. A bioimpedância cardíaca e a ecocardiografia fornecem avaliação seriada não-invasiva de parâmetros hemodinâmicos e função valvar nestes pacientes. / Objective: We hypothesized that functional mitral and tricuspid valvular incompetence (MR and TR, respectively) are reversible causes of reduced cardiac output in decompensated heart failure (DF) that accompanies systolic dysfunction in ischemic or nonischemic cardiomyopathy. Background: DF, defined as signs and symptoms of heart failure at rest, is rooted in a salt-avid state transduced by neurohormonal activation secondary to impaired renal perfusion. Functional MR and TR are reversible causes of reduced systemic blood flow. Their impact on cardiac output, thoracic fluid content, cardiac chamber dimensions, and valvular apparatus function can be monitored noninvasively, before and after optimized medical management. Methods: Fourteen male subjects (66 ± 8 years old) with reduced ejection fraction (24 ± 5%) secondary to ischemic (71%) or nonischemic (29%) cardiomyopathy, who developed DF with clinical evidence of mitral (MR) and tricuspid (TR) valvular incompetence, were each assessed by bioimpedance and echocardiography before and 1 week after optimized medical management restored compensated failure. Results: Pharmacologic elimination of DF was accompanied by a reduction in body weight (p<0.01). Hemodynamic improvements included a rise in cardiac index (2.1 to 2.6 L/min/m2; p<0.01) and a reduction in predicted pulmonary artery systolic pressure (58 to 35 mm Hg; p<0.001), thoracic fluid content (39 to 32 kOhm; p<0.001), and systemic vascular resistance (1633 to 1209 dynes/sec/cm5; p<0.001). Improvements in functional MR and TR included reductions in left and right atrial areas (27 to 24 cm and 26 to 23 cm2, respectively; p<0.001), color-flow grading of MR and TR severity (p<0.01), mitral regurgitant volume (105 to 65 mL; p<0.001), and effective MR orifice size (0.8 to 0.6 cm2; p<0.01). Conclusions: In DF, functional MR and TR contribute to reduced cardiac output, increased thoracic fluid content, and systemic vascular resistance, together with enlarged atria and valvular orifice size, which can be improved by medical management. Bioimpedance and echocardiography provide for serial noninvasive assessments of hemodynamic status and valvular function in such cases. / TEDE / BV UNIFESP: Teses e dissertações