(1175) Pulmonary Vein Thrombosis: Blood Clot in the Wrong Place?

Introduction: Pulmonary vein thrombosis (PVT) is a rare thromboembolic disease with an unclear incidence due to limited comprehensive literature and a reported mortality rate of 46%. Occlusion of the pulmonary vein is associated with high-risk complications, including arterial embolization. We review a case of PVT leading to acute hypoxemic respiratory failure.

Description: A 62-year-old male with medical history of HIV, Hepatitis C was admitted with septic shock secondary to Pseudomonas UTI, treated with levofloxacin. During hospital stay, he developed acute hypoxemic respiratory failure, necessitating non-invasive ventilation. Physical examination revealed tachypnea, use of accessory muscles, and decreased bilateral air entry. Arterial blood gas analysis showed hypoxemia [PaO2: 55%], and an infectious workup was negative. There were no acute findings on chest X-ray. Given his normal CD4 count and undetectable viral load, opportunistic fungal infections were considered less likely. CT angiogram was negative for pulmonary artery embolism but revealed a filling defect in the pulmonary vein. It was believed that the respiratory failure was due to pulmonary vein thrombosis, and therapeutic anticoagulation was initiated. The patient's oxygenation improved by day 3, and he is planned to continue anticoagulation therapy indefinitely.

Discussion: Pulmonary vein thrombosis (PVT) is an uncommon and often unrecognized thrombotic event, most commonly associated with active malignancy, lobectomy, extrinsic vein compression, and COVID-19 infection. In a retrospective study at a large multicenter tertiary care center, 1 in 5 cases were found to be idiopathic. Identified cases often presented with respiratory failure, mechanical ventilation, left atrial thrombus, ischemic stroke, and pulmonary infarction, though PVT can also be incidentally discovered. Common diagnostic modalities include CT angiography and transesophageal echocardiogram, with the left upper pulmonary vein most frequently affected. Lifelong anticoagulation is the cornerstone of treatment, though thrombectomy is occasionally performed. Clinicians should be aware of this potentially life-threatening condition, and further studies are needed to fully understand its pathology and optimal management.