Obstructive sleep apnea (OSA) is a frequent sleep-related breathing disorder with an incidence of 5-20% in the middle-aged population in Europe and Northern America . plumonary hypertension is present in 12%-34% of patients with osa.continous positive air way pressureis the main standard treatment ofOSA.Echocardiograghy is the most common non invasive imaging method for assessment the effect on right ventricular function.

Obstructive sleep apnea (OSA) is a frequent sleep-related breathing disorder with an incidence of 5-20% in the middle-aged population in Europe and Northern America . Pathophysiologic consequences of OSA are increased sympathetic activity, hypoxia, hypercapnia, increased left ventricular after-load , acute arterial hypertension, increased diastolic and systolic pressure of the right ventricle, atrial dilation. Recent studies have shown that OSA is an independent risk factor for cardiovascular mortality and morbidity. OSA has a social impact because of fragmentation of sleep leads to increased daytime sleepiness, decreased intellect, behavioral and personality changes, enuresis and sexual dysfunction.

Pulmonary hypertension is present in 12%-34% of patients with Obstructive Sleep Apnea syndrome. When PH occurs as a consequence of OSA however symptoms may not be present because of obesity and alack of physical exertion or symptoms of PH may be overlapped by other cardiovascular abnormalities.

Continuous positive air way pressure therapy is the main standard treatment of OSA works the best in the most people as positive pressure ventilation functions as a pneumatic splint for the collapsing upper air way. Echocardiography is the most common non invasive imaging method for assessment the effect of right ventricular function.

Inclusion Criteria:

• Moderate and severe OSA and candidates for initiation of CPAP therapy.

Exclusion Criteria:

• Significant lung disease ,lfet sided heart failure,end stage malignancy and advanced organ failure.

patients will be evaluated at the sleep lap of chest department of assiut university hospital over 1 year will be enrolled in the study.