To evaluate regional right ventricular (RV) myocardial velocity, strain and strain rate alterations in newly diagnosed obstructive sleep apnea (OSA) patients without systemic and pulmonary arterial hypertension and to correlate OSA severity to RV dysfunction using Velocity Vector Imaging (VVI). The OSA group consisted of 27 obese patients who were found to have moderate-to-severe OSA, and the control group of 26 age and body mass index-matched healthy subjects who were found not to have OSA on their first polysomnographic testing. All subjects underwent 24-hour ambulatory blood pressure monitoring and conventional echocardiography to exclude systemic and pulmonary arterial hypertension. Peak systolic myocardial velocities, strain and strain rates were determined at the basal and mid segments of RV free wall by VVI. Systemic and pulmonary artery pressures were within normal limits in both groups. Peak systolic myocardial velocities, strain and strain rates were significantly impaired in patients with OSA compared to controls (Table 1
). The apnea hypopnea index (AHI) correlated strongly with all indices obtained by VVI (basal velocity: r=−0.563, p<0.001; basal strain: r=−0.587, p<0.001;basal strain rate: r=−0.372, p<0.006, mid velocity: r=−0.559, p<0.001, mid strain: r=−0.689, p<0.001;mid strain rate: r=−0.658, p<0.001). The structural consequences of OSA in the RV is influenced by the severity of AHI. These effects occur independently from obesity and systemic hypertension. VVI can accurately recognize and quantify abnormalities of RV function in these subgroup of patients.
Table 1
1138 Assessment of right ventricular function during exercise by strain or strain rate imaging and ventilatory response in patients with severe pulmonary arterial hypertension
