Background Acute posterior myocardial infarction that produces immediate mitral regurgitation alters the mitral annulus and its spatial relationship with both papillary muscles. The precise deformations that cause valve insufficiency are not understood and impair efforts to repair the valve. Methods and Results In six Dorsett hybrid sheep, sonomicrometry transducers were placed around the mitral annulus (6) and at the tips and bases of both papillary muscles (4). Two weeks later, three branches of the circumflex coronary artery were occluded to infarct approximately 32% of the posterior left ventricle. This infarction produced acute 2 to 3+ mitral regurgitation in all animals, as determined by color flow Doppler velocity mapping. Before and after infarction, distance measurements between sonomicrometry transducers were used to produce the three-dimensional coordinates of each transducer every 5 ms. After infarction, the area of the annulus increased only 9.2+/-6.3% at end systole (ES). In addition, the normal shortening of the posterior papillary muscle was obliterated to allow its tip to move 1.4+/-0.6 mm closer to the centroid of the annulus at ES. After infarction, the anterior papillary muscle continued to shorten normally, but at ES, its tip and base were 0.9+/-0.7 mm and 1.3+/-0.7 mm farther from the centroid, respectively. Conclusions These deformations tend to produce a relative prolapse of leaflet tissue attached to the posterior papillary muscle and restriction of leaflet tissue attached to the anterior papillary muscle. This papillary muscle discoordination with minimal annular dilatation distorts leaflet coaptation sufficiently to produce severe mitral regurgitation.
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Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Clin Med, Div Med Emergencia, Ribeirao Preto, SP, BrazilUniv Sao Paulo, Fac Med Ribeirao Preto, Dept Clin Med, Div Med Emergencia, Ribeirao Preto, SP, Brazil
机构:
Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Zhang, Kui
Fu, Wei
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Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Fu, Wei
Dai, Qinyi
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Capital Med Univ, Beijing Anzhen Hosp, Dept Radiol, Beijing, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Dai, Qinyi
Zheng, Jubing
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Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Zheng, Jubing
Biekan, Jumatay
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Circle Cardiovasc Imaging, Calgary, AB, CanadaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Biekan, Jumatay
Wang, Yueli
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Capital Med Univ, Beijing Anzhen Hosp, Dept Echocardiog, Beijing, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Wang, Yueli
Yan, Pengyun
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Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Yan, Pengyun
Gu, Xiaoyan
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Capital Med Univ, Beijing Anzhen Hosp, Dept Echocardiog, Beijing, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Gu, Xiaoyan
Mu, Junsheng
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Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China
Mu, Junsheng
Dong, Ran
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Capital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R ChinaCapital Med Univ, Beijing Anzhen Hosp, Dept Cardiac Surg, Beijing 100029, Peoples R China