Interatrial right-to-left shunt after lung surgery: Diagnostic value of perfusion lung scanning

A 61-year-old woman presented with platypnea and orthodeoxia after right pneumonectomy for lung cancer. A perfusion lung scan taken after tracer injection in the sitting position showed an extrapulmonary uptake of radioactivity consistent with a right-to-left shunt. Such extrapulmonary uptake was no longer evident when tracer was injected in supine posture. The authors emphasize the value of perfusion lung scanning in the assessment of patients with unexplained dyspnea after thoracic surgery.