title: Improved mechanical reliability of the HeartMate XVE left ventricular assist system.
abstract: BACKGROUND
  The HeartMate XVE left ventricular assist device is a valuable treatment option for patients with end-stage heart failure. During the past several years, the XVE has undergone a series of design enhancements to improve reliability. We compared the reliability of the two most recent design iterations of the XVE pump (stitch modification to the inflow valve assembly and new inflow valve housing redesign) to the earlier VE version.
  
  
  METHODS
  A retrospective evaluation of device reliability was performed for 268 devices implanted in 245 patients (VE: n = 167 devices, 147 patients, implant dates October 16, 1998, to December 19, 2003; XVE: n = 101 devices, 98 patients, implant dates August 1, 2002, to April 14, 2004).
  
  
  RESULTS
  Median duration of device support for the VE and XVE was 159 days (range, 0 to 1,206 days) and 229 days (range, 0 to 693 days), respectively (p = 0.495). Significantly fewer major device malfunctions occurred within the XVE group as compared with the VE group (6 versus 36, respectively; p = 0.0003). The number of major device malfunctions per patient-year of support for inflow valve dysfunction, bearing wear, and other failures for the VE and XVE were 0.2 versus 0.04 (p = 0.006), 0.16 versus 0.01 (p = 0.005), and 0.06 versus 0.04 (p = 1.000), respectively. The freedom from major device malfunction at 1 year was 76% +/- 6% for the VE and 97% +/- 2% for the XVE device (p < 0.001). The freedom from death as a result of major device malfunction at 1 year was 97% +/- 2% for the VE and 98% +/- 2% for the XVE (p = 0.698).
  
  
  CONCLUSIONS
  Design enhancements to the HeartMate XVE have significantly reduced the incidence of major device malfunctions compared with the earlier VE model because of a reduction in failure modes from bearing wear and inlet valve dysfunction. Further follow-up is necessary to establish the long-term durability of the most recent XVE pump version.
authors.affiliation: Section of Cardiac Surgery, University of Michigan Health System, Ann Arbor, Michigan 48109, USA. fpagani@umich.edu
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pagani
authors.forename: James W
authors.initials: JW
authors.lastname: Long
authors.forename: Walter P
authors.initials: WP
authors.lastname: Dembitsky
authors.forename: Lyle D
authors.initials: LD
authors.lastname: Joyce
authors.forename: Leslie W
authors.initials: LW
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019544:Equipment Failure Analysis; D005260:Female; D006333:Heart Failure / Q000601:surgery*; D006352:Heart Ventricles; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012189:Retrospective Studies