35years old female patient have been admitted to our clinic by dyspnea, abdominal distension, leg edema and fatigue for last 3 months. Physical examination revealed central cyanosis, abdominal tenderness due to enlarged liver, tachycardia and 2/6 pan systolic murmur at lower left sternal border. Echocardiography revealed right heart enlargement and pulmonary hypertension. The estimated systolic pulmonary artery pressure was 70 mmHg.. There was no other structural pathology including congenital heart defects.

She was hospitalized for evaluating pulmonary hypertension etiology and we noticed severe persistent hypercapnia (PCO272%) and hypoxemia (59%, O2saturation 86%). Respiratory function test showed restrictive pattern. We couldn’t detect any lung parenchymal disease by HRCT or Ventilation and perfusion scan as a cause for respiratory failure. The work up for neuromuscular disease including Guillain Barre and Myasthenia Gravis was also negative. The findings from right heart catheterization were: mean pulmonary pressure; 34 mmHg, pulmonary vascular resistance; 5.4 woods, cardiac output 2.5 lt/m2/minute. PCWP: 12mmHg, left side pressures; normal.

We thought idiopathic pulmonary hypoventilation and pulmonary hypertension as final diagnosis. Intermittent noninvasive ventilation for respiratory failure and combination of treprostinil infusion plus ambrisartan for pulmonary hypertension were prescribed. In follow up, these symptoms of pulmonary hypertension and respiratory failure were decreased and quality of life improved apparently.