Avaliação do volume e da função atrial esquerda em pacientes com apneia obstrutiva do sono por meio da ecocardiografia tridimensional
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2009
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Oliveira, Wercules Antonio Alves de [UNIFESP]
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Poyares, Dalva Lucia Rollemberg [UNIFESP]
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Tese de doutorado
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Abstract
A apnéia obstrutiva do sono é considerada um importante problema de saúde pública,
uma vez que é altamente prevalente nos indivíduos em faixa etária produtiva e está
associada à redução da qualidade de vida, hipersonolência diurna, risco de acidentes
automobilísticos e aumento da morbidade e mortalidade cardiovascular. Há crescentes
evidências epidemiológicas e fisiopatológicas de que a apnéia obstrutiva do sono seja um
fator preditor independente de risco para acidente vascular cerebral, fibrilação atrial,
insuficiência cardíaca e morte cardiovascular. A fisiopatogênese do aumento do risco
cardiovascular nos pacientes com apnéia do sono não está completamente esclarecida.
No entanto, infere-se que haja uma importante participação da sobrecarga
catecolaminérgica e das significativas variações da pressão intratorácica como sendo
potenciais fatores de alteração do enchimento ventricular e remodelamento atrial
esquerdo. A associação entre o aumento do átrio esquerdo e risco cardiovascular tem
sido aventada por estudos epidemiológicos, os quais consideram de elevado valor
prognóstico a quantificação das dimensões desta câmara. Este é um estudo duplo-cego,
com distribuição aleatória e placebo-controlado, o qual teve como objetivos a
determinação da ocorrência de alterações morfológicas e funcionais do átrio esquerdo
por meio do ecocardiograma tridimensional, em pacientes com apnéia obstrutiva do sono,
e a avaliação do efeito do tratamento com pressão positiva contínua na reversão dessas
alterações. Cinqüenta e seis pacientes com apnéia do sono e 50 indivíduos controles
com idade e índice de massa corpórea similares foram submetidos à ecocardiografia
tridimensional e bidimensional basal. Do grupo inicial de pacientes, os indivíduos com
índice de apnéia-hipopnéia maior que 20 eventos por hora foram distribuídos a fim de que
recebessem tratamento com dispositivo efetivo de pressão positiva contínua ou
dispositivo placebo por 24 semanas. Ao longo do período de tratamento, esses indivíduos
foram submetidos a 2 exames ecocardiográficos adicionais, na 12ª e na 24ª semanas
após o início do estudo. Na avaliação ecocardiográfica basal, observou-se que havia um
menor desempenho diastólico ventricular esquerdo, maior volume atrial esquerdo e
função atrial esquerda de esvaziamento ativa aumentada nos indivíduos com apnéia do
sono em relação aos controles. A apnéia do sono e a função diastólica foram preditores
independentes do aumento do volume atrial em um modelo de regressão múltipla. Ao
final dos tratamentos foi observado no grupo que fez uso do dispositivo efetivo de
pressão positiva, uma significativa melhora no desempenho diastólico ventricular,
redução do componente ativo de esvaziamento atrial esquerdo e incremento na função
atrial esquerda de esvaziamento passivo. Não foram observadas mudanças nos valores
absolutos do volume máximo do átrio esquerdo após tratamento efetivo. Em conclusão,
este estudo revelou não somente um remodelamento atrial estrutural e funcional
associado à apnéia obstrutiva do sono, mas também o impacto do tratamento dessa
condição na dinâmica diastólica do ventrículo esquerdo e no esvaziamento do átrio
esquerdo.
Obstructive sleep apnea is an important health issue, since it is highly prevalent in the general adult population and it is associated to reduction in quality of life, excessive day time sleep, increased risk of automobile accidents and increased cardiovascular risk. There is a number of epidemiological and physiopathologic evidences that obstructive sleep apnea is an independent predictor of stroke, atrial fibrillation, heart failure, and cardiovascular death. The mechanism of the increased cardiovascular risk in patients with sleep apnea is not totally understood. However, it is assumed that the catecholaminergic overload and the significant intrathoracic pressure variation during the apneic episodes, play an important part as potential factors of ventricular filling impairment and left atrium remodeling. The association between the left atrial enlargement and cardiovascular risk has been evaluated by epidemiological studies and they consider the quantification of left atrium dimensions a strong prognostic variable. The main objectives of this doubleblinded, randomized, and placebo-control study were: (1) to evaluate left atrial volume and function in patients with obstructive sleep apnea by means of the real-time threedimension echocardiography; (2) to determine the impact of treatment with continuous positive airway pressure device on the left atrial dynamics and left ventricular function. Fifty-six patients with sleep apnea and 50 controls with similar age and body mass index underwent basal real-time three-dimensional and two-dimension echocardiography. From the initial patients group, those individuals with apnea-hypopnea index greater than 20 were randomized in order to receive effective treatment or placebo for 24 weeks. They underwent two additional echocardiographic evaluations, after 12 weeks and 24 week of treatment. In the basal echocardiographic evaluation, we observed in the patients group: lower diastolic performance, larger left atrial volume, and reduced left atrial passive function. Obstructive sleep apnea and left ventricular diastolic function were independent predictors of an increased left atrial volume in a multiple regression model. In the effective treatment group we observed a significant improvement in the diastolic performance, reduction in the left atrial active emptying, and increase in the left atrial passive emptying from the baseline to the 24 week echocardiographic evaluation. No significant changes were found on LA fundamental volumes after treatment. As conclusion, we demonstrated using the real-time three-dimensional echocardiography that obstructive sleep apnea places a functional burden on the left atrium, resulting in remodeling. This remodeling could be, at least partially, reversed after effective treatment with CPAP.
Obstructive sleep apnea is an important health issue, since it is highly prevalent in the general adult population and it is associated to reduction in quality of life, excessive day time sleep, increased risk of automobile accidents and increased cardiovascular risk. There is a number of epidemiological and physiopathologic evidences that obstructive sleep apnea is an independent predictor of stroke, atrial fibrillation, heart failure, and cardiovascular death. The mechanism of the increased cardiovascular risk in patients with sleep apnea is not totally understood. However, it is assumed that the catecholaminergic overload and the significant intrathoracic pressure variation during the apneic episodes, play an important part as potential factors of ventricular filling impairment and left atrium remodeling. The association between the left atrial enlargement and cardiovascular risk has been evaluated by epidemiological studies and they consider the quantification of left atrium dimensions a strong prognostic variable. The main objectives of this doubleblinded, randomized, and placebo-control study were: (1) to evaluate left atrial volume and function in patients with obstructive sleep apnea by means of the real-time threedimension echocardiography; (2) to determine the impact of treatment with continuous positive airway pressure device on the left atrial dynamics and left ventricular function. Fifty-six patients with sleep apnea and 50 controls with similar age and body mass index underwent basal real-time three-dimensional and two-dimension echocardiography. From the initial patients group, those individuals with apnea-hypopnea index greater than 20 were randomized in order to receive effective treatment or placebo for 24 weeks. They underwent two additional echocardiographic evaluations, after 12 weeks and 24 week of treatment. In the basal echocardiographic evaluation, we observed in the patients group: lower diastolic performance, larger left atrial volume, and reduced left atrial passive function. Obstructive sleep apnea and left ventricular diastolic function were independent predictors of an increased left atrial volume in a multiple regression model. In the effective treatment group we observed a significant improvement in the diastolic performance, reduction in the left atrial active emptying, and increase in the left atrial passive emptying from the baseline to the 24 week echocardiographic evaluation. No significant changes were found on LA fundamental volumes after treatment. As conclusion, we demonstrated using the real-time three-dimensional echocardiography that obstructive sleep apnea places a functional burden on the left atrium, resulting in remodeling. This remodeling could be, at least partially, reversed after effective treatment with CPAP.
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Citation
OLIVEIRA, Wercules Antonio Alves de. Avaliação do volume e da função atrial esquerda em pacientes com apnéia obstrutiva do sono por meio da ecocardiografia tridimensional. 2009. 113 f. Tese (Doutorado em Ciências) – Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, 2009.