Assessing mitral valve area and orifice geometry in calcific mitral stenosis: a new solution by real-time three-dimensional echocardiography.
BACKGROUND
Planimetry of mitral valve area (MVA) is difficult in calcific mitral stenosis (CaMS) in which limiting orifice is near the annulus, and unlike rheumatic mitral stenosis (RhMS), does not present an area for planimetry at the leaflet tips. Moreover, pressure half time (PHT)-derived MVA (MVA(PHT)) has limitations in patients with CaMS in whom there are coexisting conditions that affect LV chamber compliance. We tested the hypothesis that real-time 3-dimensional echocardiography (RT3D) can guide measurement at the narrowest orifice in CaMS.


METHODS
In 34 patients with CaMS, MVA by RT3D (MVA(RT3D)) was obtained using a color-defined planimetry technique performed "en face" at the smallest annular orifice cross-section (diastolic maximum). MVA(RT3D) and MVA(PHT) were compared with an independent standard: MVA by continuity equation (MVA(CEQ)). In a subgroup of 10 patients with CaMS or RhMS, the 3-dimensional shape of the stenotic mitral valve was examined, guided by color flow mapping.


RESULTS
MVA(PHT) overestimated the mitral orifice area compared with MVA(CEQ) (2.01 +/- 0.52 cm(2) vs 1.75 +/- 0.46 cm(2); P = .037), whereas there was no significant difference in MVA(RT3D) and MVA(CEQ) (1.83 +/- 0.52 cm(2) vs 1.75 +/- 0.46 cm(2), respectively, P = .61). MVA(RT3D) had a greater correlation with MVA (CEQ) than MVA(PHT) (R = 0.86 vs 0.59 MVA(RT3D) vs MVA(PHT), respectively). There was better agreement between MVA by RT3D and MVA by continuity equation than MVA by PHT and MVA by continuity equation (difference in MVA: 0.23 +/- 0.15 cm(2) vs 0.43 +/- 0.29 cm(2); P < .0001, MVA(RT3D) - MVA(CEQ) vs MVA(PHT) - MVA(CEQ,) respectively). In CaMS, there was a tubular geometry to the valve shape. In contrast, RhMS had a doming funnel-shaped geometry.


CONCLUSIONS
RT3D provides an accurate measurement of MVA in CaMS. In contrast with the doming valve shape present in RhMS, the limiting anatomic orifice area occurs at the annulus in CaMS as measured by RT3D and reflects the effective orifice area as present in a tubular valve geometry.
Chu
John W
JW
Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Levine
Robert A
RA
Chua
Sarah
S
Poh
Kian-Keong
KK
Morris
Eleanor
E
Hua
Lanqi
L
Ton-Nu
Thanh-Thao
TT
Hung
Judy
J
D000368:Aged; D002114:Calcinosis / Q000000981:diagnostic imaging*; D003199:Computer Systems; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging*; D008946:Mitral Valve Stenosis / Q000000981:diagnostic imaging*; D009929:Organ Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity