title: Pseudoaneurysm formation after medtronic freestyle porcine aortic bioprosthesis implantation: a word of caution.
abstract: BACKGROUND
  A growing literature describes aneurysmal deterioration after implantation of the stentless porcine aortic Medtronic Freestyle bioprosthesis (MFB; Medtronic Inc, Minneapolis, MN), with some suggesting inadequate tissue fixation with immune response as a cause. However, disjointed reports make the significance of these findings difficult to interpret. We address this concern by aggregating available data.
  
  
  METHODS
  We reviewed institutional data, the Food and Drug Administration's Manufacturer and User Facility Device Experience registry, and the medical literature for mention of aneurysm or pseudoaneurysm after MFB. Case details were aggregated, and the rate of aneurysmal deterioration was estimated. Immunohistopathologic examination of institutional explanted specimens was performed to elucidate a cause.
  
  
  RESULTS
  We found 42 cases of aneurysmal deterioration with adequate detail for analysis; all occurred with full root replacement and valve sizes ranging from 23 to 29 mm. The rate of aneurysmal deterioration considering all data sources was 1.1% (9 of 851; 95% confidence interval, 0.5% to 2.0%) vs 4.7% (4 of 86; 95% confidence interval, 1.3% to 11.5%) at our institution, where yearly surveillance imaging is performed. Rate of aneurysmal deterioration appeared constant until 5 years after the operation; however, events are reported out to 10 years. Consistent with previous reports, histopathology demonstrated an immune cell infiltrate in areas of MFB wall breakdown.
  
  
  CONCLUSIONS
  Aneurysmal deterioration is an increasingly described complication of MFB implantation as a full root, with an incidence as high as 4.7%. Given the observed immune reaction and lack of occurrence in smaller (19-mm and 21-mm) valve sizes, inadequate pressure fixation of larger valves is a potential etiology. Patients with MFB require annual surveillance imaging, and consideration of this complication should factor into preoperative decision making because treatment mandates redo root replacement, which may not be feasible in high-risk patients.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Englum
authors.affiliation: Department of Pathology, Duke University Medical Center, Durham, North Carolina.
authors.forename: Elizabeth N
authors.initials: EN
authors.lastname: Pavlisko
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Molly C
authors.initials: MC
authors.lastname: Mack
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Asvin M
authors.initials: AM
authors.lastname: Ganapathi
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Schechter
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Hanna
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina. Electronic address: gchad.hughes@duke.edu.
authors.forename: G Chad
authors.initials: GC
authors.lastname: Hughes
mesh_terms: D000328:Adult; D017541:Aneurysm, False / Q000175:diagnosis / Q000209:etiology*; D000792:Angiography; D000818:Animals; D017545:Aortic Aneurysm, Thoracic / Q000175:diagnosis / Q000209:etiology*; D001021:Aortic Valve / Q000601:surgery; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000601:surgery*; D001705:Bioprosthesis / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D021621:Imaging, Three-Dimensional; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D011183:Postoperative Complications; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013552:Swine; D014057:Tomography, X-Ray Computed; D055815:Young Adult