INTRODUCTION: Exertional hypoxemia in Post Lung Transplant patients has multiple etiologies. Pulmonary vasculature related anastamotic complications are uncommon causes. We present a case of anastamotic pulmonary artery stenosis presenting clinically as worsening exertional hypoxemia.
CASE PRESENTATION: 56 year old male with history of Dermatomyositis and Pulmonary fibrosis presented for lung transplant evaluation initially. He is an ex smoker with 30 pack year smoking history. Functional status on presentation was NYHA Class III requiring 2L oxygen with exercise.He underwent Left single lung transplant and Post Transplant course was complicated by Reperfusion injury requiring mechanical ventilation. He also developed atrial flutter, which was successfully cardioverted with Propafenone. Transesophageal echocardiogram (TEE) was normal. He developed DVT and Acetinobacter pneumonia during hospitalization. Patient responded to medical management and subsequently discharged home. Six-minute walk test prior to discharge showed significant desaturations with exercise and 4 liters oxygen prescribed. 3 months post transplant the patient continued to be on supplemental oxygen and Ventilation Perfusion scan (V/Q scan) showed mismatched perfusion defects in left apex. Clinical diagnosis of pulmonary embolism made and therapeutic anticoagulation was continued.5 months post transplant, FEV1 dropped. He underwent Bronchoscopy and anastamotic stenosis was noted.Ultraflex bronchial stent placed and on subsequent follow up improved FEV1 was noted.8 months post transplant worsening exercise-induced hypoxemia noted. Repeat V/Q scan showed a persistent Left apical perfusion defect with 39% perfusion to left lung. Echocardiogram (ECHO) performed and systolic pulmonary pressure (PAP) estimated at 48mmhg. Pre transplant ECHO estimated systolic PAP was 36 mm hg. Pulmonary arteriogram revealed band like stenosis in the left main pulmonary artery (PA). PA pressures proximal to the lesion were 45/16 with mean of 27 and post stenosis 15/10 with mean of 12 mm hg.12 × 20 wallstent placed and dilated to 12 mm. Post stent placement PA pressures were 25/10 and mean of 16.Subsequent 6 minute walk test showed no exercise induced desaturation and home oxygen was discontinued.
DISCUSSIONS: Dyspnea and hypoxemia in post transplant patients are usually related to rejection, infection and anatomical problems of airways. Pulmonary vasculature complications are uncommon. The time of presentation from transplant varies from immediate post op period to few years and clinical presentation varies accordingly. Refractory respiratory failure and Right heart failure in early post op period to worsening dyspnea in delayed presentations. In patients, presenting with gradual worsening of respiratory function as presented in this report, initial work up is targeted for detection of the usual culprits. He underwent Bronchoscopy, which revealed anastomotic stenosis and rectified with endobronchial stent. No rejection detected and infectious workup was negative. V/Q scan was suggestive of pulmonary embolism and therapeutic anticoagulation prescribed. The patient continued to be symptomatic which prompted work up to evaluate for pulmonary vasculature abnormalities. Of note the patient had improvement in perfusion to transplanted lung from 39% post op to 47% serially. ECHO revealed elevated Systolic PA pressure of 48 mm hg from 36mm hg pre-transplant. Clinical suspicion of pulmonary artery stenosis made and angiography performed. Stenosis of left main pulmonary artery detected and corrected with endovascular stent. The patient had immediate improvement in oxygenation status and was off supplemental oxygen. Unlike previously reported, exertional hypoxemia is the only sign of PA stenosis in the transplanted lung in this patient and complete reversal of hypoxemia after rectifying the defect noted.
CONCLUSION: Pulmonary artery stenosis is an unlikely differential for graft dysfunction in Lung transplant patients, but unique in being amenable to therapy with dramatic results.
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