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Two-dimensional Doppler echocardiography calculates left ventricular stroke volume from the product of the left ventricular outflow tract (LVOT) area and the velocity time integral obtained by pulse Doppler. Two-dimensional methods assume that the outflow tract area is circular when in fact it is elliptical. Three-dimensional echocardiography need not rely on this assumption and so may be more accurate. The purpose of this study was to compare the accuracy of two-dimensional with three-dimensional techniques for the measurement of stroke volume.
Thermodilution stroke volume (TDSV) was the standard against which three echocardiographic methods were compared: 1. Two-dimensional echocardiography with a circular LVOT area (2DSV), 2. Three-dimensional echocardiography with a planimetered LVOT area (PLANSV) and 3. Three-dimensional echocardiography derived from left ventricular volume measurements (VOLSV). Adult patients referred for right heart catheterization were consented for the study.
The study population consisted of 10 females and 14 males with a mean age of 60 +/- 8 years and body surface area of 2.0 +/- 0.4 square meters. Repeated measures analysis of variance indicated that 2DSV and VOLSV underestimated TDSV with average differences and 95% confidence intervals of −21 +/- 10 and −24 +/- 10 milliliters respectively (p<0.05), whereas PLANSV accurately predicted TDSV with an average difference and 95% confidence interval of −1 +/- 10 milliliters (p>0.05). Bland-Altman plots showed that 2DSV and VOLSV underestimated TDSV with wide limits of agreement. The average difference and 95% limits of agreement were −21 (−54 to 13) and −23 (−84 to 38) milliliters for 2DSV and VOLSV respectively. However, Bland-Altman plot for PLANSV showed no systematic bias with an average difference and 95% limits of agreement of −1 (−41 to 40) milliliters.
Three-dimensional echocardiography with planimetry of the LVOT was the only accurate technique for measurement of stroke volume. Two-dimensional and volumetric three-dimensional echocardiography techniques were inaccurate due to both underestimation and wide ranges of agreement.
Poster Sessions, Expo North
Monday, March 11, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Imaging: CRT/New Technology
Abstract Category: 18. Imaging: Echo
Presentation Number: 1312-337
- 2013 American College of Cardiology Foundation