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Pulsed Doppler (PD) method of measuring left ventricular (LV) outflow time velocity integral (TVI) and LV stroke volume (SV) in the subvalvular zone is the advocated method for use in the continuity equation (CE) for determination of aortic valve area (AVA) in aortic stenosis (AS). This preference is because of the concern that if continuous wave Doppler (CWD) is employed, it would include pre-stenotic flow acceleration and overestimate the TVI and SV, and thus underestimate AS severity. In this study, we explored the accuracy of CWD-measured TVI approach in assessing AS severity by comparing it to the standard and accepted PD method.
We studied 100 patients with suspected AS. From LV outflow dimension and PD recording of flow velocity in the subvalvular zone, LV outflow TVI and SV values were obtained and the AVA was further derived using the distal maximal velocity profile recorded by CWD. The same beat was also used to obtain the proximal LVOT flow TVI by CWD, and these measurements were used to calculate the SV and AVA. The TVI, SV and AVA values obtained by CWD method were compared to those obtained by PD.
Of the 100 patients, we were able to obtain optimal quality CWD of proximal LVOT flow in 87 patients. In these, the mean values of LVOT TVI (cm) by PD and CWD were 21 + 4.2 and 23.4 + 5.1 respectively (p<0.001). The mean values for AVA (cm squared) by PD and CWD approaches were 0.85 + 0.35 and 0.94 + 0.43 respectively (p<0.001). CWD approach correlated closely with PD method both in computing SV (r = 0.71, p <0.001) and AVA (r = 0.93, p<0.001). With a correction factor of – 0.2 applied to AVA obtained by CWD, 95% cases were correctly categorized.
CWD approach of measuring proximal LVOF velocity profile in patients with AS is an accurate approach for incorporation into the continuity equation for determining AS severity. This method has the advantage of avoiding sample volume placement errors and using the same beat for measuring both proximal and distal maximal flow velocity in aortic stenosis.
Poster Sessions, Expo North
Saturday, March 09, 2013, 10:00 a.m.-10:45 a.m.
Session Title: Imaging: Echo – Aortic Valve Diseases
Abstract Category: 18. Imaging: Echo
Presentation Number: 1144-365
- 2013 American College of Cardiology Foundation