His abnormal echocardiogram prompted further evaluation of the etiology and severity of his elevated pulmonary pressures. Additional laboratory assessment revealed normal thyroid function and no significant abnormalities on autoimmune workup. Pulmonary function testing (Table 17.1) did not reveal significant changes that could account for severity of elevated pulmonary pressures.

Additional imaging was performed to assess for possibility of pulmonary embolism as etiology of his progressive shortness of breath and echocardiographic findings. Ventilation (Fig. 17.2)/perfusion (Fig. 17.3) scanning was performed and revealed bilateral patchy perfusion defects without significant ventilation abnormalities.

Based on V/Q, there was concern for chronic thromboembolic pulmonary hypertension (CTEPH). A more definitive evaluation with CT pulmonary angiogram (CTPA) (Fig. 17.4) was therefore requested. CTPA revealed enlarged pulmonary arteries but no evidence of significant parenchymal lung disease or pulmonary emboli.