Assessing Mitral Valve Area and Orifice Geometry in Calcific Mitral Stenosis: A New Solution by Real-Time Three-Dimensional Echocardiography
published online 14 July 2008.
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 (MVAPHT) 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 (MVART3D) was obtained using a color-defined planimetry technique performed “en face” at the smallest annular orifice cross-section (diastolic maximum). MVART3D and MVAPHT were compared with an independent standard: MVA by continuity equation (MVACEQ). 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
MVAPHT overestimated the mitral orifice area compared with MVACEQ (2.01 ± 0.52 cm2 vs 1.75 ± 0.46 cm2; P = .037), whereas there was no significant difference in MVART3D and MVACEQ (1.83 ± 0.52 cm2 vs 1.75 ± 0.46 cm2, respectively, P = .61). MVART3D had a greater correlation with MVA CEQ than MVAPHT (R = 0.86 vs 0.59 MVART3D vs MVAPHT, 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 cm2 vs 0.43 ± 0.29 cm2; P < .0001, MVART3D − MVACEQ vs MVAPHT − MVACEQ, respectively). In CaMS, there was a tubular geometry to the valve shape. In contrast, RhMS had a doming funnel-shaped geometry.
Conclusion
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.
Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
Reprint requests: Judy Hung, MD, Cardiac Ultrasound Laboratory, Massachusetts General Hospital, 55 Fruit Street, VBK 508, Boston, MA 02114
Dr John W. Chu was supported in part by a grant from the National Heart Foundation of New Zealand, Auckland, New Zealand. This work was also supported in part by K23HL004504 and R21EB005294 (J.H.) and R01HL072265 (R.A.L.). There are no conflicts to declare.
ABSTRACT