Dimensional ratios of normal mitral valve structures: a tool for determining the degree of geometric distortion in individual patients.
OBJECTIVE
One objective of mitral valve repair is to restore the distorted mitral apparatus geometry to its normal dimensions specific for each patient. Because all dimensions of the normal aortic and mitral valves should be related, it was hypothesized that, in the presence of a normal aortic annulus, it would be possible to determine the dimensions of the structures needed for mitral valve repair.


METHODS
In seven sheep, sonometric ultrasound crystals were implanted at the left and right trigones (T1, T2), lateral annulus (P1, P2), and the tips of the anterior and posterior papillary muscles (Ml, M2). The distances T1-T2, M1-M2, T1-M1, T2-M2, P1-P2, P1-M1, and P2-M2 were measured at end-systole (ES), end-diastole (ED), and maximum and minimum lengths. Using these measured distances, fractional relationships were computed, and the average fractional relationship was used to determine a 'calculated' distance. The 'measured' and 'calculated' distances were then compared using a paired t-test.


RESULTS
All fractional relationships were close to 1, with ED 1.00 +/- 0.21, ES 0.99 +/- 0.19, maximum length 0.99 +/- 0.19, and minimum length 0.94 +/- 0.21. The intertrigonal distance (T1-T2) expanded by 4.19 +/- 3.81%, and the transverse diameter (P1-P2) contracted by -6.15 +/- 3.69% from ED to ES. The interpapillary muscle distance (M1-M2) contracted -22.3 +/- 6.5%. The two distances with the least amount of contraction were those of T1-M1 and T2-M2, with contractions of -3.06 +/- 2.39% and -3.27 +/- 1.37%, respectively. P1-M1 and P2-M2 expanded 5.60 +/- 2.89% and 6.84 +/- 3.60% from ED to ES.


CONCLUSIONS
The mitral valve dimensions and calculated fractional relationships were similar in all sheep. As shown previously, the ratio of aortic annulus diameter (easily measured echocardiographically) to the intertrigonal distance (T1-T2) is 0.79 and 0.80 in humans and sheep, respectively. This distance can be used to determine normal mitral valve geometry and, therefore, preoperatively to calculate the degree of geometric distortion present in individual patients.
Kegel
Corrine L
CL
The International Heart Institute of Montana Foundation at Saint Patrick Hospital and Health Sciences Center and The University of Montana, Missoula, MT 59802, USA.
Joudinaud
Thomas M
TM
Lim
Khee Hiang
KH
Goetz
Wolfgang A
WA
Lansac
Emmanuel
E
Weber
Patricia A
PA
Ganesan
Kumar
K
Duran
Carlos M G
CM
D000818:Animals; D001794:Blood Pressure; D001026:Coronary Artery Bypass; D003971:Diastole; D008943:Mitral Valve / Q000000981:diagnostic imaging*; D023421:Models, Animal; D008955:Models, Cardiovascular; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000000981:diagnostic imaging*; D012756:Sheep; D013599:Systole; D014465:Ultrasonics; D014463:Ultrasonography