The Pathology of Pulmonary Vein Radiofrequency Ablation
Alexandra E Kovach, George Z Cheng, Colleen L Channick, Richard Channick, Henning A Gaissert, Ashok Muniappan, Richard L Kradin. Massachusetts General Hospital (MGH), Boston, MA; MGH, Boston, MA
Background: Radiofrequency ablation of pulmonary veins is a common therapeutic intervention for atrial fibrillation. Pulmonary vein stenosis and venoocclusive disease are recognized complications of this procedure. A recent case at our hospital showed associated inflammatory pseudotumor formation. The spectrum of pathologies addressing post-ablation complications has not been previously reviewed.
Design: Two surgical resections from MGH were reviewed by light microscopy, one of pseudotumor formation with associated pulmonary vein stenosis. A literature search was performed for the following terms: “histology,” “pathology,” and “histopathology” each with “pulmonary vein radiofrequency ablation atrial fibrillation.” Pathologic features of the MGH cases were compared with those in existing reports.
Results: Published descriptions were identified from 22 subjects, including 1 from MGH. The earliest lesions (2-6 days post-ablation) demonstrated hyperemic pulmonary vein branches (23%), some obliterated by thrombi (14%), and vacuolar changes in associated nerve fibers (14%). At 21-22 days post-ablation, well-delineated ablation sites were present and consistent with direct thermal injury, with fragmented collagen, granulation tissue, necrotic foci, and thinned adjacent myocardium. More established lesions (4-37 months) had transmural fibrosis of the intervened pulmonary vein (53%), pulmonary venoocclusive change of collateral veins associated with marked ventilation-perfusion mismatches (14%), thrombosis and pulmonary parenchymal infarction (9%), interstitial and mediastinal fibrosis (9%), venous tortuosity (5%), and hypertensive arteriopathy (5%). In an additional recent case at MGH, a left hilar soft tissue mass was identified in association with superior pulmonary vein stenosis in a patient 4 years post-ablation. On resection, this proved to be an inflammatory pseudotumor composed of myofibroblasts in an organizing pneumonia-type pattern with adjacent osseous metaplasia. Pulmonary venoocclusive change was also a prominent feature.
Conclusions: Literature on the histopathology of post-radiofrequency ablation complications is limited. The severity of vascular pathology appears to increase with the post-ablation interval. Although pulmonary vascular changes are the most common finding in more established lesions, fibroinflammatory changes including mediastinal fibrosis and pulmonary pseudotumor formation, likely later complications of thermal injury, should be considered in the differential diagnosis of these cases.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 298, Tuesday Afternoon