Geometric determinants of chronic functional ischemic mitral regurgitation: insights from three-dimensional cardiac magnetic resonance imaging.
OBJECTIVE
The assessment of three-dimensional (3-D) mitral valve geometry in patients with chronic functional ischemic mitral valve regurgitation (FIMR) has been hampered by a lack of adequate imaging techniques. The study aim was to use a clinically applicable cardiac magnetic resonance imaging (MRI) technique to assess the 3-D mitral annular, leaflet and papillary muscle geometry in pigs with chronic FIMR.


METHODS
Ten pigs with moderate chronic FIMR induced by catheter-based coiling of the circumflex artery, were examined using cardiac MRI. The reconstruction of 3-D data from two-dimensional cardiac MRI scans allowed the mitral annulus and leaflet geometries to be assessed. Using 3-D morphology scans, the spatial position of the posterior papillary muscle (PPM) relative to the anterior papillary muscle (APM), mitral annulus and anterior (A-trig) and posterior (P-trig) trigones was assessed. Using dedicated software for image analysis, data were transferred to a Cartesian coordinate system (x,y,z) for geometric analysis. Ten healthy pigs served as controls.


RESULTS
Compared to controls, at end-systole in the chronic FIMR group the PPM was significantly displaced (p <0.05) from the APM (38 +/- 2 versus 23 +/- 1 mm), A-trig (48 +/- 2 versus 36 +/- 1 mm) and P-trig (41 +/-1 versus 33 +/- 1 mm). There was no significant apical PPM displacement (20 +/- 2 versus 20 +/- 1 mm). The annular area (1,240 +/- 90 versus 850 +/- 90 mm2), septolateral distance (36 +/- 2 versus 26 +/- 1 mm), commissure-to-commissure distance (38 +/- 2 versus 33 +/- 1 mm), mean tenting height (8 +/- 1 versus 5 +/- 0 mm), maximum tenting height (10 +/- 1 versus 7 +/- 0 mm), tenting volume (2,600 +/- 400 versus 1,500 +/- 200 mm3), and occlusional leaflet area (1,820 +/- 110 versus 1,120 +/- 70 mm2) were each significantly increased.


CONCLUSIONS
This clinically applicable cardiac MRI modality permitted a detailed geometric insight to be made into the mitral annular, leaflet and PPM geometries that cause FIMR. Such a reliable tool for geometric mitral valve analysis has previously been demonstrated only by using invasive techniques. Hence, this approach holds promise for further clarifying the pathogenesis of chronic FIMR and improving preoperative surgical planning.
Jensen
Henrik
H
Department of Cardiothoracic and Vascular Surgery and Institute of Clinical Medicine, Aarhus University Hospital, Skejby Sygehus, Denmark. hjensen@dadlnet.dk
Jensen
Morten Ø
MØ
Ringgaard
Steffen
S
Smerup
Morten H
MH
Sorensen
Thomas S
TS
Kim
Won Y
WY
Sloth
Erik
E
Wierup
P
P
Hasenkam
J Michael
JM
Nielsen
Sten L
SL
D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008943:Mitral Valve / Q000473:pathology* / Q000503:physiopathology; D008944:Mitral Valve Insufficiency / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D009200:Myocardial Contraction / Q000502:physiology; D017202:Myocardial Ischemia / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D010210:Papillary Muscles / Q000473:pathology; D015203:Reproducibility of Results; D012720:Severity of Illness Index