Evaluation of Subclinical Right Ventricular Dysfunction in Obstructive Sleep Apnea Patients Using Velocity Vector Imaging

Background: The aims of this study were to evaluate subclinical regional right ventricular (RV) dysfunction in newly diagnosed obstructive sleep apnea (OSA) patients without systemic and pulmonary arterial (PA) hypertension, and to correlate OSA severity to RV dysfunction, using both velocity vector imaging (VVI)-derived strain imaging and tissue Doppler imaging (TDI). Methods and Results: The OSA group consisted of 27 patients and the control group consisted of 26 healthy participants. All participants underwent 24-h ambulatory blood pressure monitoring. Peak systolic myocardial velocities, strain, and strain rate (SR) were determined at the basal and mid segments of the RV free wall by VVI. Additionally, RV myocardial velocities were assessed by pulsed-wave TDI. Patients with OSA had significantly impaired VVI-derived peak systolic myocardial velocities, strain, and SR (P<0.0001 for all). RV isovolumic acceleration (IVA) was the only TDI-derived parameter that was significantly impaired (P<0.0001). RV IVA (r=-0.512, P<0.0001), RV mid free wall strain (r=0.568, P<0.0001) and SR (r=0.519, P<0.0001) revealed the best correlations with apnea hypopnea index (AHI). Conclusions: Subclinical RV dysfunction is present in OSA patients despite normal systemic and PA pressures. Tissue Doppler-derived RV IVA and VVI-derived RV deformation can accurately recognize and quantify RV function abnormalities in this subgroup of patients. (Circ J 2010; 74: 312-319)