title: Off-pump transapical mitral valve replacement: evaluation after one month.
abstract: OBJECTIVE
  The present study investigates outcomes one month after implanting pigs with a novel mitral valved stent.
  
  
  METHODS
  A novel nitinol stent custom designed for this study included a bovine pericardial valve. Six pigs received a valved stent into the mitral position by means of the transapical implantation technique. Afterwards, haemodynamic stability and valve function were assessed, immediately after implantation (n = 6), 4 weeks (n = 4) and 8 weeks (n = 1) thereafter using transoesophageal echocardiography (TEE), ventriculography and cardiac computed tomography (CT). Four of 6 surviving pigs were sacrificed at 4 weeks after implantation and one at 8 weeks thereafter.
  
  
  RESULTS
  Optimal deployment and positioning were obtained in all but one animal. This animal died of unrecognized imperfect valved stent positioning after 4 days. The average mean gradient across the new valves and the left ventricular outflow tract (LVOT) were small. Mild regurgitation developed after valved stent deployment in one of six animals just after 1 h, and in none thereafter. All animals exhibited normal haemodynamics after mitral valved stent implantation, and stability was maintained throughout the monitoring period. Migration, embolization and paravalvular leakage were not evident in the remaining animals after 4 and 8 weeks. Gross evaluation revealed that 50-70% of the atrial element was covered by tissue growth at 4 weeks/8 weeks.
  
  
  CONCLUSIONS
  This study demonstrates adequate deployment and anchorage of a unique, repositionable mitral valved stent. A good valve function was revealed in animals observed for 4 weeks and in one pig after 8 weeks.
authors.affiliation: Department of Cardiovascular Surgery,  University Hospital Schleswig-Holstein, Campus Kiel, Kiel,  Germany.
authors.forename: Kenji
authors.initials: K
authors.lastname: Iino
authors.forename: Jessica
authors.initials: J
authors.lastname: Boldt
authors.forename: Lucian
authors.initials: L
authors.lastname: Lozonschi
authors.forename: Anja
authors.initials: A
authors.lastname: Metzner
authors.forename: Jan
authors.initials: J
authors.lastname: Schoettler
authors.forename: Rainer
authors.initials: R
authors.lastname: Petzina
authors.forename: Jochen
authors.initials: J
authors.lastname: Cremer
authors.forename: Georg
authors.initials: G
authors.lastname: Lutter
mesh_terms: D000497:Alloys; D000818:Animals; D017548:Echocardiography, Transesophageal; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D006439:Hemodynamics / Q000502:physiology; D019060:Minimally Invasive Surgical Procedures / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D008943:Mitral Valve / Q000000981:diagnostic imaging / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000209:etiology; D011474:Prosthesis Design; D015607:Stents; D034421:Sus scrofa; D014057:Tomography, X-Ray Computed
chemical_list: D000497:Alloys; C013616:nitinol