Ventricular-arterial coupling in obstructive sleep apnea

Arterial elastance (Ea) and systolic elastance are important parameters determining effective functional interaction of heart and vessels. The aims of this study were to (1) compare arterial (arterial elastance index [EaI]) and ventricular (end-systolic elastance [Ees] and end-diastolic elastance [Eed]) elastance in subjects with obstructive sleep apnea (OSA) and patients with treated ‘high-risk’ hypertension (HHT) and (2) test whether these parameters in OSA patients can be improved by continuous positive airway pressure (CPAP) therapy. Echocardiographic parameters of cardiac and vascular stiffness (EaI, Ees, and Eed) were quantified in 28 patients with OSA (mean [standard deviation], age 51 [11] years; 79% male) and 28 treated subjects with HHT (mean [standard deviation], age 48 [12] years; 61% male). Twenty-three OSA patients were treated with CPAP for median of 26 weeks. Ea was calculated from stroke volume and systolic BP and adjusted by body area (EaI). Both study groups had preserved and comparable left ventricle contractility. There was no significant differences in EaI (P = .94), Ees (P = .5), Eed (P = .63), and arterial-ventricular interaction (P = .62) between OSA and HHT groups. After CPAP therapy, there was a significant reduction in EaI (paired t test, P = .013) and arterial-ventricular interaction (paired t test, P = .004). Ees (P = .17) and Eed (P = .66) parameters did not change significantly. OSA and HHT patients have similar parameters of elastance and ventricular-arterial coupling. CPAP treatment in OSA patients significantly improved ventricular-arterial coupling.