Abstract Background: Thoracic aortic dissection (TAD) is a highly lethal cardiovascular disease. Injury to the intima and media allows pulsatile blood to enter the media, leading to dissection formation. Inflammatory cells then infiltrate the site of aortic injury to clear dead cells and damaged tissue. This excessive inflammation may play a role in aneurysm formation after dissection. Methods: Using immunohistochemistry, we compared aortic tissues from patients with acute TAD (n = 11), patients with chronic TAD (n = 35), and donor controls (n = 20) for the presence of CD68+ macrophages, neutrophils, mast cells, and CD3+ T lymphocytes. Results: Tissue samples from patients with acute or chronic TAD generally had significantly more inflammatory cells in both the medial and adventitial layers than did the control samples. In tissues from patients with acute TAD, the adventitia had more of the inflammatory cells studied than did the media. The pattern of increase in inflammatory cells was similar in chronic and acute TAD tissues, except for macrophages, which were seen more frequently in the adventitial layer of acute TAD tissue than in the adventitia of chronic TAD tissue. Conclusions: The inflammatory cell content of both acute and chronic TAD tissue was significantly different from that of control tissue. However, the inflammatory cell profile of aneurysmal chronic TAD was similar to that of acute TAD. This may reflect a sustained injury response that contributes to medial degeneration and aneurysm formation.

BACKGROUND:Traditionally, aortic root replacement has most commonly involved mechanical composite valve grafts, which have excellent durability but necessitate lifelong anticoagulation. Stentless porcine xenografts (bioroots) are a recently developed alternative that enable root replacement without the necessity of long-term anticoagulation. This study examined the early and late outcomes of aortic root replacement with porcine bioroots.METHODS:Porcine bioroots were used for root replacement in 132 patients. Of these, 129 (97.7%) required graft extensions for ascending aortic replacement, and 55 (41.7%) underwent aortic arch replacement. Twenty-three operations (17.4%) were reoperations. Twenty-four patients (18.2%) had aortic dissection. Early and late outcomes were ascertained by reviewing medical records. Changes in New York Heart Association (NYHA) class were used to assess improvements in functional status. Follow-up echocardiography results were reviewed to assess bioprosthetic valve function and changes in left ventricular ejection fraction.RESULTS:There were 10 operative deaths (7.6%), 9 of which were directly related to intraoperative ventricular failure. Nine patients (6.8%) had late valve-related complications, including 5 patients with prosthetic endocarditis (3 died), 1 annular pseudoaneurysm, and 3 sudden, unexplained deaths. Survivors' NYHA status and left ventricular ejection fraction improved significantly. No structural valve dysfunction was evident during follow-up. Actuarial survival was 85.6% +/- 3.1% at 1 year and 77.8% +/- 4.8% at 5 years.CONCLUSIONS:Aortic root replacement with porcine xenografts can be performed with respectable early and late outcomes, even when combined with aortic arch replacement. Further follow-up is necessary to evaluate long-term bioroot durability.