Pulmonary artery (PA) stricture occurs most often in the setting of congenital malformation. PA stricture is uncommon in the adult population, and PA stricture following radiation therapy is exceedingly rare.
A 57-year-old male presented to the pulmonary clinic with progressive dyspnea. Past medical history was significant for small cell lung cancer treated with radiation therapy and chemotherapy three years prior to presentation. On physical exam, he was a well-nourished male in no acute distress. Room air SaO2 was 91% at rest and 87% with minimal exertion. He was afebrile with normal vital signs. Neck and heart exams were within normal limits. Breath sounds were decreased bilaterally. There was no edema. Oxygen was prescribed and the patient was referred for testing. Pulmonary function testing revealed normal spirometry with a flow-volume loop suggestive of mild airflow obstruction. Diffusing capacity was within normal limits. Cardiopulmonary exercise testing demonstrated a mild ventilatory limitation with desaturation, but no evidence of a circulatory limitation. The patient returned to the outpatient office complaining of moderate chest pain without radiation or associated symptoms. Sublingual nitroglycerin completely relieved the pain and subsequent EKG revealed nonspecific changes and p-pulmonale. The patient was then evaluated by cardiac catheterization, which revealed normal coronary vessels with elevated PA pressures (48/26). A bilateral lower extremity duplex scan was negative. Ventilation-perfusion scanning, however, demonstrated complete lack of perfusion to the left lung. (Figure 1) Given the history of cancer and radiation therapy and lack of perfusion to the left lung, the differential diagnosis included intrinsic and extrinsic compression of the left PA. A spiral CT revealed a left PA stricture without evidence of thrombus or extrinsic compression; this finding was confirmed by pulmonary angiography. (Figure 2) Of note is the fact that this PA abnormality had not been observed on a CT obtained prior to radiation therapy. A stent was placed in the area of stricture with resulting 100% PA patency and improvement in dyspnea.
Pulmonary artery stricture/stenosis is rare in the adult population. It may present as an isolated lesion but is more often a feature of a complex congenital heart disease. Reported cases in the literature attribute PA stenosis to extrinsic compression secondary to mediastinal fibrosis, tumor of the lung or esophagus, aortic aneurysm, or as a consequence of surgical intervention.
Pulmonary artery stricture is a rare but possible complication of radiation therapy which can be a cause of unexplained dyspnea.
F.E. Loftus, None.