Temporal Changes in Interpapillary Muscle Dynamics as an Active Indicator of Mitral Valve and Left Ventricular Interaction in Ischemic Mitral Regurgitation

JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY

卷:64

Article

Kalra, Kanika¹  Wang, Qian²  McIver, Bryant V.¹  Shi, Weiwei¹  Guyton, Robert A.¹  Sun, Wei²  Sarin, Eric L.¹  Thourani, Vinod H.¹  Padala, Muralidhar¹ 

[1] Emory Univ, Carlyle Fraser Heart Ctr, Div Cardiothorac Surg, Struct Heart Dis Res & Innovat Lab, Atlanta, GA 30313 USA

[2] Georgia Inst Technol, Coulter Dept Biomed Engn, Atlanta, GA 30332 USA

关键词: magnetic resonance imaging;    mitral force balance;    mitral valve tethering;    myocardial infarction;    papillary muscles;    regional wall motion;    regurgitant fraction;    ventricular imaging;    tenting area;   

DOI  :  10.1016/j.jacc.2014.07.988

来源: Elsevier

【 摘 要 】

BACKGROUND Regional subpapillary myocardial hypokinesis may impair lateral reduction in the interpapillary muscle distance (IPMD) from diastole to systole, and adversely affect mitral valve geometry and tethering. OBJECTIVES The goal of this study was to investigate the impact of impaired lateral shortening in the interpapillary muscle distance on mitral valve geometry and function in ischemic heart disease. METHODS To quantify ventricular size/shape, regional myocardial contraction, lateral shortening of the IPMD, mitral valve geometry, and severity of mitral regurgitation, 67 patients with ischemic heart disease underwent cardiac magnetic resonance imaging, and a correlation analysis of measured parameters was performed. The impact of reduced IPMD shortening on mitral valve (dys) function was confirmed in swine and in a physiological computational mitral valve model. RESULTS Lateral shortening of the IPMD from diastole to systole was severely reduced in patients with moderate/severe ischemic mitral regurgitation (9.6 +/- 2.8 mm), but preserved in mild IMR (11.5 +/- 3.4 mm). Left ventricular size and ejection fraction did not differ between the groups. In swine with subpapillary infarction and impaired IPMD, mitral regurgitation was evident within 1 week, compared to those pigs with a nonpapillary infarction and preserved IPMD. In the controlled computational valve model, IPMD had the maximal impact on regurgitation, and was exacerbated with additional annular dilation. CONCLUSIONS By using cardiac magnetic resonance imaging in humans, we demonstrated that it is the impairment of lateral shortening between the papillary muscles, and not passive ventricular size, that governs the severity of mitral regurgitation. Loss of lateral shortening of IPMD tethers the leaflet edges and impairs their systolic closure, resulting in mitral regurgitation, even in small ventricles. Understanding the lateral dynamics of ventricular-valve interactions could aid the development of new repair techniques for ischemic mitral regurgitation. (C) 2014 by the American College of Cardiology Foundation.

【 授权许可】

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