Left Atrial Volume and Function in Patients With Obstructive Sleep Apnea Assessed by Real-Time Three-Dimensional Echocardiography
ABSTRACT Studies have suggested that obstructive sleep apnea (OSA) contributes to the deterioration of left ventricular diastolic function. This may lead to atrial myocardial overstretching and enlargement, which could be associated with increased cardiovascular risk. The aim of this study was to evaluate left atrial (LA) volume and function in patients with OSA compared with controls without OSA and their associations with any left ventricular diastolic abnormalities using real-time 3-dimensional echocardiography (RT3DE).
Fifty-six patients with mild to severe OSA and 50 controls of similar age and with similar body mass indexes, blood pressure, and frequency of hypertension were analyzed. All subjects underwent polysomnography and RT3DE.
A larger 3-dimensional maximum LA volume indexed for body surface area, larger volume before atrial contraction, and higher active atrial ejection fraction were found in patients with OSA (P < .01 for all). Mitral annular early diastolic velocity (E') was reduced in patients with OSA (P = .03), whereas late diastolic velocity (A') and the ratio of mitral valve early diastolic velocity to mitral annular early diastolic velocity (E/E') were increased in the same group (P < .05 for both). In addition, a lower E'/A' ratio was also found in the OSA group (P = .02). An increase in 3-dimensional maximum LA volume indexed for body surface area was observed, depending on OSA severity. The apnea-hypopnea index and E/E' ratio were independent predictors of an increase in 3-dimensional maximum LA volume in a multiple regression model.
Using RT3DE, this study demonstrates that OSA induces a functional burden on the left atrium, resulting in remodeling. These functional and structural changes are related to the impairment of diastolic function in this population.
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ABSTRACT: Background Sleep deprivation contributes to the development and recurrence of ventricular arrhythmias. However, the electrophysiological changes in ventricular myocytes in sleep deprivation are still unknown. Material and Methods Sleep deprivation was induced by modified multiple platform technique. Fifty rats were assigned to control and sleep deprivation 1, 3, 5, and 7 days groups, and single ventricular myocytes were enzymatically dissociated from rat hearts. Action potential duration (APD) and transient outward current (Ito) were recorded using whole-cell patch clamp technique. Results Compared with the control group, the phases of APD of ventricular myocytes in 3, 5, and 7 days groups were prolonged and APD at 20% and 50% level of repolarization (APD20 and APD50) was significantly elongated (The APD20 values of control, 1, 3, 5, and 7 days groups: 5.66±0.16 ms, 5.77±0.20 ms, 8.28±0.30 ms, 11.56±0.32 ms, 13.24±0.56 ms. The APD50 values: 50.66±2.16 ms, 52.77±3.20 ms, 65.28±5.30 ms, 83.56±7.32 ms, 89.24±5.56 ms. P<0.01, n=18). The current densities of Ito significantly decreased. The current density-voltage (I-V) curve of Ito was vitally suppressed downward. The steady-state inactivation curve and steady-state activation curve of Ito were shifted to left and right, respectively, in sleep deprivation rats. The inactivation recovery time of Ito was markedly retarded and the time of closed-state inactivation was markedly accelerated in 3, 5, and 7 days groups. Conclusions APD of ventricular myocytes in sleep deprivation rats was significantly prolonged, which could be attributed to decreased activation and accelerated inactivation of Ito.Medical science monitor: international medical journal of experimental and clinical research 01/2015; 21:542-9. DOI:10.12659/MSM.893414 · 1.22 Impact Factor
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ABSTRACT: Our understanding of the left atrium is growing, although there are many aspects that are still poorly understood. The left atrium size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes and of different cardiovascular disorders, such as, but not limited to, atrial fibrillation, congestive heart failure, mitral regurgitation and stroke. Left atrial function has been conventionally divided into three integrated phases: reservoir, conduit and booster-pump. The highly dynamic left atrium and its response to the stretch and secretion of atrial neuropeptides leaves the left atrium far from being a simple transport chamber. The aim of this review is to provide an understanding of the left atrial physiology and its relation to disorders within the heart.International Journal of Molecular Sciences 09/2014; 15(9):15146-15160. DOI:10.3390/ijms150915146 · 2.34 Impact Factor
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ABSTRACT: Background: The mechanisms associated with the cardiovascular consequences of obstructive sleep apnea include abrupt changes in autonomic tone, which can trigger cardiac arrhythmias. The authors hypothesized that nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea. Objective: To analyze the relationship between obstructive sleep apnea and abnormal heart rhythm during sleep in a population sample. Methods: Cross-sectional study with 1,101 volunteers, who form a representative sample of the city of São Paulo. The overnight polysomnography was performed using an EMBLA® S7000 digital system during the regular sleep schedule of the individual. The electrocardiogram channel was extracted, duplicated, and then analyzed using a Holter (Cardio Smart®) system. Results: A total of 767 participants (461 men) with a mean age of 42.00 ± 0.53 years, were included in the analysis. At least one type of nocturnal cardiac rhythm disturbance (atrial/ventricular arrhythmia or beat) was observed in 62.7% of the sample. The occurrence of nocturnal cardiac arrhythmias was more frequent with increased disease severity. Rhythm disturbance was observed in 53.3% of the sample without breathing sleep disorders, whereas 92.3% of patients with severe obstructive sleep apnea showed cardiac arrhythmia. Isolated atrial and ventricular ectopy was more frequent in patients with moderate/severe obstructive sleep apnea when compared to controls (p < 0.001). After controlling for potential confounding factors, age, sex and apnea-hypopnea index were associated with nocturnal cardiac arrhythmia. Conclusion: Nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea and the prevalence increases with disease severity. Age, sex, and the Apnea-hypopnea index were predictors of arrhythmia in this sample.Arquivos Brasileiros de Cardiologia 09/2014; DOI:10.5935/abc.20140142 · 1.12 Impact Factor