Direct measurement of left ventricular outflow tract by transthoracic real-time 3D-echocardiography increases accuracy in assessment of aortic valve stenosis

TY - JOUR

T1 - Direct measurement of left ventricular outflow tract by transthoracic real-time 3D-echocardiography increases accuracy in assessment of aortic valve stenosis

AU - Khaw, Alexander V.

AU - von Bardeleben, Ralph Stephan

AU - Strasser, Christina

AU - Mohr-Kahaly, Susanne

AU - Blankenberg, Stefan

AU - Espinola-Klein, Christine

AU - Münzel, Thomas F.

AU - Schnabel, Renate

PY - 2009/7/24

Y1 - 2009/7/24

N2 - Background: Evaluation of aortic valve stenosis is a major clinical application of echocardiography. The widely employed continuity equation requires determination of the left ventricular outflow tract (LVOT) area. We aimed at testing whether direct area measurement in a volume data set is superior to conventional calculation from the LVOT diameter. Methods: We performed LVOT measurement in 20 normal subjects and 83 patients with moderate to severe aortic stenosis with a transthoracic real-time three-dimensional echocardiography (3D-TTE) technique in two systolic frames. The off-line 3D-evaluation allows full choice of section planes within the acquired volume data set. The aortic valve area was calculated from systolic LVOT areas. These results were compared to area values obtained by M-mode LVOT-diameters (area = π * (d / 2)2). In addition, the calculated aortic valve orifices were compared to invasive measurements or direct planimetry in the transthoracic or transesophageal examination. Results: Two independent observers found a reduction in LVOT area during systole (p < 0.001). Often a more ellipsoid-like shaped LVOT resulted at end-systole which was shown by a reduction (p < 0.001) of the LVOT longitudinal to oblique axis ratio. 3D-TTE determination of aortic valve orifice areas (mean difference: - 0.04 ± 0.09 cm2) showed a lesser deviation from the invasively or planimetrically measured areas than conventionally calculated LVOT areas (mean difference: - 0.1 ± 0.1 cm2) using the continuity equation (p < 0.001). Conclusions: The tested transthoracic 3D-echocardiography technique offers non-invasive measurement of the LVOT and aortic valve area based on the continuity equation during systole and thus improves accuracy and, additionally, agreement of aortic valvular area determination with invasive and direct measurements.

AB - Background: Evaluation of aortic valve stenosis is a major clinical application of echocardiography. The widely employed continuity equation requires determination of the left ventricular outflow tract (LVOT) area. We aimed at testing whether direct area measurement in a volume data set is superior to conventional calculation from the LVOT diameter. Methods: We performed LVOT measurement in 20 normal subjects and 83 patients with moderate to severe aortic stenosis with a transthoracic real-time three-dimensional echocardiography (3D-TTE) technique in two systolic frames. The off-line 3D-evaluation allows full choice of section planes within the acquired volume data set. The aortic valve area was calculated from systolic LVOT areas. These results were compared to area values obtained by M-mode LVOT-diameters (area = π * (d / 2)2). In addition, the calculated aortic valve orifices were compared to invasive measurements or direct planimetry in the transthoracic or transesophageal examination. Results: Two independent observers found a reduction in LVOT area during systole (p < 0.001). Often a more ellipsoid-like shaped LVOT resulted at end-systole which was shown by a reduction (p < 0.001) of the LVOT longitudinal to oblique axis ratio. 3D-TTE determination of aortic valve orifice areas (mean difference: - 0.04 ± 0.09 cm2) showed a lesser deviation from the invasively or planimetrically measured areas than conventionally calculated LVOT areas (mean difference: - 0.1 ± 0.1 cm2) using the continuity equation (p < 0.001). Conclusions: The tested transthoracic 3D-echocardiography technique offers non-invasive measurement of the LVOT and aortic valve area based on the continuity equation during systole and thus improves accuracy and, additionally, agreement of aortic valvular area determination with invasive and direct measurements.

KW - Aortic valve stenosis

KW - Left ventricular outflow tract

KW - Three-dimensional Echocardiography

UR - http://www.scopus.com/inward/record.url?scp=67649882059&partnerID=8YFLogxK

U2 - 10.1016/j.ijcard.2008.04.070

DO - 10.1016/j.ijcard.2008.04.070

M3 - SCORING: Journal article

C2 - 18657334

AN - SCOPUS:67649882059

VL - 136

SP - 64

EP - 71

JO - INT J CARDIOL

JF - INT J CARDIOL

SN - 0167-5273

IS - 1

ER -