INTRODUCTION: Vascular complications are rare but serious causes of morbidity and mortality following lung transplantation. Pulmonary artery stenosis at the anastomosis can cause dyspnea and pulmonary hypertension in transplant patients. Diagnosis of pulmonary artery stenosis can be achieved using ventilation perfusion scanning, echocardiography and pulmonary angiogram. In the literature, most anastomotic complications have been surgically repaired. We report a case of significant pulmonary artery stenosis in a single lung transplant recipient successfully treated with angioplasty and stent placement.
CASE PRESENTATION: A 70 year old male with a history of coronary artery disease who underwent left single lung transplantation for idiopathic pulmonary fibrosis developed exertional dyspnea 2 weeks after transplantation. The patient had an uneventful surgery and immediate post-operative course. When the patient was re-admitted for dyspnea, EKG, cardiac enzymes and CT angiogram were negative. Ventilation perfusion scan showed diffusely decreased perfusion and ventilation in the left lung with perfusion worse than ventilation. Split pulmonary function testing was done revealing 16.7% function of the left lung. Bronchoscopy was performed showing granulation tissue at the left mainstem bronchus anastomosis which was debrided in the operating room. After discharge he remained with symptomatic dyspnea and oxygen requirement. Four weeks post-transplant, repeat bronchoscopy was done demonstrating mucous plugging but no bronchus stenosis or rejection on biopsy. Echocardiography showed normal left and right ventricular function and a pulmonary artery systolic pressure of 30 mmHg. Arterial blood gas revealed a pH of 7.433, a PaCO2 of 32.6, PaO2 of 70.1 on room air with a normal methemoglobin level. A repeat bronchoscopy was done 6 weeks post-transplant showing normal bronchial anatomy and a biopsy negative for rejection. Seven weeks post-transplant, patient was seen in clinic with continued symptoms and a New York Heart Association III functional classification. At that time his oxygen saturation on 3L of oxygen per minute was 92%. He had pulmonary function testing revealing an FEV1 of 2.59L (88%), FVC of 3.63L (97%). Patient was then sent for pulmonary angiogram which demonstrated a severe stenosis at the anstomosis of the pulmonary artery. The pulmonary artery pressure in the pre-stenotic segment was 25 mmHg and 2–4 mmHg in the post-stenotic segment, making a transtenotic gradient of 21–23 mmHg. A 10mm diameter stent was placed and inflated using a balloon. There was improvement in room air saturation during the procedure from 88% to 96%. Patient's 6 min walk distance changed from 1150 feet requiring 4L O2 to 1125 feet without any O2 supplementation after stenting.
DISCUSSIONS: Vascular stenosis is uncommon after lung transplantation. The incidence of pulmonary vascular stenosis in one series was reported to be 1.75%. (1). Unilateral vascular stenosis in double lung transplants may go unnoticed secondary to the opposite lung compensating for the defect. Nearly all reported clinically significant cases were in single lung transplants. Diagnosis is usually suspected based on otherwise unexplained symptoms and preferential perfusion to the native lung on ventilation/perfusion scans. Diagnosis is confirmed with pulmonary angiogram. Until 1994 surgical repair was the only therapy and had associated morbidity and mortality risk. In 1994, Ferretti was the first to successfully percutaneously stent a stenosis using a balloon expandable stent. Since that time there have been several reports of this method as a surgery sparing treatment.
CONCLUSION: In post-lung transplant patients with otherwise unexplained dyspnea or pulmonary arterial hypertension, pulmonary artery stenosis should be considered in the differential. Percutaneous stenting of the artery is an effective treatment which avoids risky surgery.
DISCLOSURE: Lisa Kopas, None.