The Journal of Thoracic and Cardiovascular Surgery
Volume 136, Issue 3 , Pages 557-565, September 2008

The effect of pure mitral regurgitation on mitral annular geometry and three-dimensional saddle shape

  • Tom C. Nguyen, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • Akinobu Itoh, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • Carl J. Carlhäll, MD, PhD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • Department of Clinical Physiology, University Hospital, Linköping, Sweden
    • ,
  • Wolfgang Bothe, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • Tomasz A. Timek, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • Daniel B. Ennis, PhD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • Robert A. Oakes, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • ,
  • David Liang, MD, PhD

      Affiliations

    • Division of Cardiovascular Medicine, Stanford, California
    • ,
  • George T. Daughters, MS

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • Research Institute, Palo Alto Medical Foundation, Palo Alto, California
    • ,
  • Neil B. Ingels Jr., PhD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • Research Institute, Palo Alto Medical Foundation, Palo Alto, California
    • ,
  • D. Craig Miller, MD

      Affiliations

    • Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California
    • Corresponding Author InformationAddress for reprints: D. Craig Miller, MD, Department of Cardiothoracic Surgery, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, CA 94305-5247.

Received 23 May 2007; received in revised form 26 November 2007; accepted 18 December 2007.

Objective

Chronic ischemic mitral regurgitation is associated with mitral annular dilatation in the septal-lateral dimension and flattening of the annular 3-dimensional saddle shape. To examine whether these perturbations are caused by the ischemic insult, mitral regurgitation, or both, we investigated the effects of pure mitral regurgitation (low pressure volume overload) on annular geometry and shape.

Methods

Eight radiopaque markers were sutured evenly around the mitral annulus in sheep randomized to control (CTRL, n = 8) or experimental (HOLE, n = 12) groups. In HOLE, a 3.5- to 4.8-mm hole was punched in the posterior leaflet to generate pure mitral regurgitation. Four-dimensional marker coordinates were obtained radiographically 1 and 12 weeks postoperatively. Mitral annular area, annular septal-lateral and commissure–commissure dimensions, and annular height were calculated every 16.7 ms.

Results

Mitral regurgitation grade was 0.4 ± 0.4 in CTRL and 3.0 ± 0.8 in HOLE (P < .001) at 12 weeks. End-diastolic left ventricular volume index was greater in HOLE at both 1 and 12 weeks; end-systolic volume index was larger in HOLE at 12 weeks. Mitral annular area increased in HOLE predominantly in the commissure–commissure dimension, with no difference in annular height between HOLE versus CTRL at 1 or 12 weeks, respectively.

Conclusion

In contrast with annular septal-lateral dilatation and flattening of the annular saddle shape observed with chronic ischemic mitral regurgitation, pure mitral regurgitation was associated with commissure–commissure dimension annular dilatation and no change in annular shape. Thus, infarction is a more important determinant of septal-lateral dilatation and annular shape than mitral regurgitation, which reinforces the need for disease-specific designs of annuloplasty rings.

Abbreviations and Acronyms: ED, end diastole, ES, end systole, CC, commissure–commissure, IMR, ischemic mitral regurgitation, LV, left ventricular, MR, mitral regurgitation, SL, septal-lateral, 3D, 3-dimensional, TTE, transthoracic echocardiography

CTSNet classification: 17, 22, 33, 35

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 This work was supported by Grants HL-29589 and HL-67025 from the National Heart, Lung and Blood Institute. Doctors Nguyen was a Leah McConnell Cardiovascular Surgical Research Fellow and recipient of the Thoracic Society Foundation Research Fellowship Award. Dr Itoh received funding from the Uehara Memorial Foundation, and Dr Carlhäll received funding from the Swedish Heart and Lung Foundation and the County Council of Östergötland, Sweden. Dr Bothe received stipend support from the Deutsche Herzstiftung.

 Presented at the 87th Annual Meeting of the American Association for Thoracic Surgery Washington, DC, May 2007.

PII: S0022-5223(08)01108-2

doi:10.1016/j.jtcvs.2007.12.087

The Journal of Thoracic and Cardiovascular Surgery
Volume 136, Issue 3 , Pages 557-565, September 2008

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