Abstract
Obstructive sleep apnea (OSA) causes recurrent apneas due to upper respiratory tract collapse, leading to sympathetic nervous system hyperactivation and increased cardiovascular risk. Moderate and severe forms of obstructive sleep apnea are associated with increased atrial volumes and affect left ventricular diastolic and then systolic function. Right ventricular ejection fraction can be accurately assessed via three-dimensional echocardiography, while bidimensional imaging can only provide a set of surrogate parameters to characterize systolic function (tricuspid annulus plane systolic excursion, right ventricular fractional area change, and lateral S'). Tissue Doppler imaging is a more sensitive tool in detecting functional ventricular impairment, but its use is limited by angle dependence and the unwanted influence of tethering forces. Two-dimensional speckle tracking echocardiography is considered more suitable for the assessment of ventricular function, as it is able to distinguish between active and passive wall motion. Abnormal strain values, a marker of subclinical myocardial dysfunction, can be detected even in patients with normal ejection fraction and chamber volumes. The left ventricular longitudinal strain is more affected by the presence of obstructive sleep apnea than circumferential strain values. Although the observed OSA-induced changes are subtle, the benefit of a detailed echocardiographic screening for subclinical heart failure in OSA patients on therapy adherence and outcome should be addressed by further studies.
Highlights
Obstructive sleep apnea (OSA) causes recurrent apneas due to upper respiratory tract collapse, leading to sympathetic nervous system hyperactivation and increased cardiovascular risk
Right ventricular ejection fraction can be accurately assessed via three-dimensional echocardiography, while bidimensional imaging can only provide a set of surrogate parameters to characterize systolic function
It is estimated that 4% of middle-aged males and 2% of females suffer from OSA [1], a condition that induces refractory hypertension, oxidative stress, endothelial dysfunction, and increased sympathetic tone, leading to increased cardiovascular risk [2]
Summary
Moderate and severe forms of obstructive sleep apnea are associated with increased atrial volumes and affect left ventricular diastolic and systolic function. E differences regarding diastolic dysfunction prevalence among subjects with OSA are explained by the echocardiographic parameters used in defining it and by other patient characteristics such as associated comorbidities (obesity and diabetes) and significant differences regarding OSA severity (the group analyzed by Korcarz et al included patients with an average AHI 39.8, while the desaturation index in Wachter’s moderate-to-severe OSA subgroup was only 20 events/hour). Left ventricular Tei index (LV-MPI), illustrating both systolic and diastolic functions, is higher in subjects with severe sleep apnea (0.64 ± 0.14) compared to those with mild OSA (0.50 ± 0.09; p < 0.01) [9] or to controls [14],. Altekin et al [14] Zhou et al [15] Dursunoglu et al [9] Wachter et al [16] Holtstrand et al [8] Varghese et al [10] Vural et al [17] Altekin et al [14] Dursunoglu et al [9] Wachter et al [16] Varghese et al [10] Altekin et al [11] Varghese et al [10] Dursunoglu et al [9] Wachter et al [16] Imai et al [13] Imai et al [13]
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