The primary outcome variable for efficacy is patient status one year after the start of treatment, where status is classified as either failure or success. Failure is defined as death or evidence of progressive obstruction at any time over the course of treatment as defined in the protocol. Success constitutes complete or partial response to treatment or stability of disease. Secondary outcome variables for efficacy are survival, time from diagnosis of pulmonary vein stenosis until failure, and change in patient classification on a scale measuring the severity of the obstructive disease.