title: Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis.
abstract: BACKGROUND
  The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function.
  
  
  METHODS
  Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated.
  
  
  RESULTS
  PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function.
  
  
  CONCLUSIONS
  PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function.
authors.affiliation: School of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: Joe Luis
authors.initials: JL
authors.lastname: Pantoja
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, California; Department of Bioengineering, University of California, San Francisco, San Francisco, California; Veterans Affairs Medical Center, San Francisco, California.
authors.forename: Liang
authors.initials: L
authors.lastname: Ge
authors.affiliation: Veterans Affairs Medical Center, San Francisco, California.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Medicine, University of California, San Francisco, San Francisco, California.
authors.forename: William G
authors.initials: WG
authors.lastname: Morrel
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, California; Department of Bioengineering, University of California, San Francisco, San Francisco, California; Veterans Affairs Medical Center, San Francisco, California.
authors.forename: Julius M
authors.initials: JM
authors.lastname: Guccione
authors.affiliation: Department of Cardiothoracic Surgery, New York University, New York, New York; New York Harbor Veterans Affairs Medical Center, New York, New York.
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Grossi
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, California; Department of Bioengineering, University of California, San Francisco, San Francisco, California; Veterans Affairs Medical Center, San Francisco, California. Electronic address: mark.ratcliffe@med.va.gov.
authors.forename: Mark B
authors.initials: MB
authors.lastname: Ratcliffe
mesh_terms: D000818:Animals; D020342:Finite Element Analysis; D008297:Male; D008944:Mitral Valve Insufficiency / Q000503:physiopathology / Q000601:surgery*; D017202:Myocardial Ischemia / Q000503:physiopathology / Q000601:surgery*; D010210:Papillary Muscles / Q000601:surgery*; D012756:Sheep; D013314:Stress, Mechanical; D013318:Stroke Volume