title: Factors influencing left ventricular outflow tract obstruction following a mitral valve-in-valve or valve-in-ring procedure, part 1.
abstract: OBJECTIVE
  To determine the factors influencing left ventricular outflow tract (LVOT) area reduction after a mitral valve-in-valve (VIV) or a valve-in-ring (VIR) procedure.
  
  
  BACKGROUND
  Transcatheter heart valves (THVs) are increasingly used in performing a VIV or a VIR procedure in high-risk patients. Although less invasive, a potential complication is LVOT obstruction. However, the factors predisposing to LVOT obstruction are ill defined.
  
  
  RESULTS
  To understand the effects of the various factors, the study was carried out in three parts: To understand the effect of VIV and VIR on reduction in LVOT area with special attention to different surgical heart valve (SHV) orientations and depth of THV implant. This was carried out in porcine and cadaver hearts. To quantify aorto-mitral-annular (AMA) angle in 20 patients with or without mitral disease and to derive a static computational model to predict LVOT obstruction. To study the effect of SHV design on LVOT obstruction after VIV. This was carried out as a bench test. LVOT area reduction was similar after VIV irrespective of orientation of the mitral SHV implantation as it pinned open the SHV leaflets. Similar effect was seen after VIR. The degree of LVOT obstruction was partly determined by AMAangle and was inversely proportional. SHV design, ring design, and depth of SPAIEN XT implantation also had effect on LVOT obstruction.
  
  
  CONCLUSIONS
  A possibility of LVOT obstruction should be considered when performing a VIV and VIR procedure. Type of SHV, flexible ring, less obtuse AMA angle, and depth of SAPIEN XT implant can influence the risk.
authors.affiliation: Department of Cardiothoracic Surgery and Cardiology, Guy's and St. Thomas' Hospital, London, United Kingdom.
authors.forename: Vinnie
authors.initials: V
authors.lastname: Bapat
authors.affiliation: Department of Cardiothoracic Surgery and Cardiology, Guy's and St. Thomas' Hospital, London, United Kingdom.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pirone
authors.affiliation: Department of Cardiothoracic Surgery and Cardiology, Guy's and St. Thomas' Hospital, London, United Kingdom.
authors.forename: Stam
authors.initials: S
authors.lastname: Kapetanakis
authors.affiliation: Department of Cardiothoracic Surgery and Cardiology, Guy's and St. Thomas' Hospital, London, United Kingdom.
authors.forename: Ronak
authors.initials: R
authors.lastname: Rajani
authors.affiliation: Department of Biomedical Engineering, Kings College, London, United Kingdom.
authors.forename: Steven
authors.initials: S
authors.lastname: Niederer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002102:Cadaver; D002815:Chordae Tendineae / Q000601:surgery; D015331:Cohort Studies; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000601:surgery*; D023421:Models, Animal; D011474:Prosthesis Design; D018570:Risk Assessment; D013552:Swine; D016896:Treatment Outcome; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery
keywords: aortic; left ventricle; mitral; valve