Impact of obstructive sleep apnea on the right ventricle

Right ventricular (RV) involvement in obstructive sleep apnea syndrome (OAS) is controversial. The aim of this study was to determine a correlation between echocardiographic parameters of RV function and severity of OSA assessed by the apnea- hypopnea index (AHI).

Sixty patients with suspected OSA were enrolled. All patients had overnight polygraphy and an echocardiographic assessment of RV structure and function. Patients were divided into three groups: a control group (n=20) with an AHI<5/h, a group of mild to moderate OSA (n=18) with an AHI=5-30/h and a group of severe OSA (n=22) with AHI≥30/h.

There were no differences of age, body mass index and sex among the three groups. There was no difference in systolic pulmonary pressure. RV free wall thickness, end-diastolic surface and right atrium surface were statistically higher in OSA patients compared with controls. The peak systolic myocardial velocity at tricuspid lateral annulus S' were significantly lower in patients compared with controls (14.5±3 vs 12.2±2 cm / s, p<0.001; respectively). This decrease was greater in patients with severe OSA compared with mild to moderate OSA (11.4±3 vs 13.0±1 cm/s, p=0.05, respectively). Right ventricular myocardial performance index (MPI) was significantly higher in OSA compared with controls (0.55±0.12 vs 0.46±0.14, p=0.024, respectively) but it was not correlated with the severity of IAH.

In OSA patients, there was a significant RV dysfunction independently of pulmonary pressure, although the correlation with the severity of IAH was moderate.