implications with regard to quantification of aortic stenosis severity area can be predicted from the pressure recovery phenomenon: practical Discrepancies between catheter and Doppler estimates of valve effective orifice (original) (raw)
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Assessment of Aortic Valve Stenosis Severity
Circulation, 2000
Background-Fluid energy loss across stenotic aortic valves is influenced by factors other than the valve effective orifice area (EOA). We propose a new index that will provide a more accurate estimate of this energy loss. Methods and Results-An experimental model was designed to measure EOA and energy loss in 2 fixed stenoses and 7 bioprosthetic valves for different flow rates and 2 different aortic sizes (25 and 38 mm). The results showed that the relationship between EOA and energy loss is influenced by both flow rate and aortic cross-sectional area (A A) and that the energy loss is systematically higher (15Ϯ2%) in the large aorta. The coefficient (EOAϫA A)/(A A ϪEOA) accurately predicted the energy loss in all situations (r 2 ϭ0.98). This coefficient is more closely related to the increase in left ventricular workload than EOA. To account for varying flow rates, the coefficient was indexed for body surface area in a retrospective study of 138 patients with moderate or severe aortic stenosis. The energy loss index measured by Doppler echocardiography was superior to the EOA in predicting the end points, which were defined as death or aortic valve replacement. An energy loss index Յ0.52 cm 2 /m 2 was the best predictor of adverse outcomes (positive predictive value of 67%). Conclusions-This new energy loss index has the potential to reflect the severity of aortic stenosis better than EOA. Further prospective studies are necessary to establish the relevance of this index in terms of clinical outcomes.
Echocardiography, 2009
. However, the phenomenon of pressure recovery may lead to significant overestimation of aortic valve (AV) gradients by Doppler echocardiography (echo). We hypothesized that echo-derived gradients will be higher in mild-moderate AS because of pressure recovery. We studied 94 patients who had echo and cardiac caths in a span of 1 week. The mean age was 72 ± 13 years, 54% males, 79% had coronary artery disease, and the mean left ventricular ejection fraction was 45 ± 22%. The mean cardiac output and cardiac indices were 5.1 ± 1.4/2.7 ± 0.6 (l/mt), (l/m 2 ), respectively. For those with mild AS, echo overestimated gradients in 9.5% of patients (4/42) by an average of 19 mmHg, thus misclassifying the degree of stenosis. In those with moderate AS, 14% (3/21) were misclassified as severe AS (gradient overestimation by an average of 13.6 mmHg). In those with severe AS, echo underestimated gradients in 13% (4/31) by an average of 22.7 mmHg. The aorta at the sinotubular junction was 2.8 cm in those patients with mild AS in whom gradients were overestimated by more than 20 mmHg compared to a sinotubular junction diameter of 3.12 cm in those with mild AS and no overestimation of gradients. The AV area/aortic root ratio was 0 .4 in those with mild AS and 0.2 in those with severe AS (P < 0.05). (ECHOCARDIOGRAPHY, Volume 26, October 2009) pressure recovery, aortic stenosis, valvular heart disease Doppler echocardiography (echo) has traditionally been used to assess and quantify the degree of aortic stenosis (AS). Studies have shown very good correlation between Dopplerderived gradients and gradients derived by cardiac catheterization (cath). 1 According to the American College of Cardiology/American Heart Association (ACC/AHA) guidelines, cardiac cath to assess the valve gradient is necessary only if there is a discrepancy between Doppler-derived gradients and the clinical picture. 2 However, in clinical practice, Dopplerderived echo gradients sometimes overestimate aortic valve gradients and thus misclassify the degree of stenosis. 3 Pressure recovery is a wellknown phenomenon that leads to overestimation of Doppler gradients in patients with prosthetic aortic valves, coarctation of the aorta, and hypertrophic cardiomyopathy. 4-8 Pressure recovery can also occur with native AS, especially when the ratio of the aortic valve area to the aortic root is high. This tends to occur with mild-moderate degrees of stenosis and smaller aortic root sizes. 9 However, the phenomenon of pressure recovery in native AS and the frequency with which this leads to overestimation of aortic valve gradients in clinical practice has not been well studied in literature. The purpose of this study is to assess, in a real-world clinical setting, the frequency with which significant overestimation of gradients occur by Doppler echo in AS.
Circulation, 2004
Background-All indices of aortic stenosis (AS) rely on measurements of mean transvalvular pressure gradient (⌬P) and flow rate. Because the gradient is reversed during late ejection, the late systolic left ventricular (LV)-aortic pressure crossover may be an erroneous landmark of end-ejection. The aortic incisura should be a better reference to calculate indices of AS invasively. Methods and Results-The accuracy of the pressure crossover and the incisura to define end-ejection was assessed in a chronic AS experimental model (9 dogs) with the use of an implantable flowmeter and Doppler echocardiography as reference. In 288 hemodynamic recordings analyzed (aortic valve area [AVA]: 0.74Ϯ0.46 cm 2), ejection ended 37Ϯ29 ms after the pressure crossover but almost simultaneously with the incisura (2Ϯ17 ms). Pressure crossover error accounted for significant errors in the measurement of ⌬P (95% limits of agreement, ϩ0 to ϩ7 mm Hg) and AVA (Ϫ0.1 to ϩ0.2 cm 2). These errors were reduced to less than half with the use of the incisura to define end-ejection. Additionally, the agreement with Doppler-derived AS indices was best with use of the incisura. Pressure crossover error was maximal in situations of higher output, moderate orifice narrowing, higher arterial compliance, and lower vascular resistance. In 32 consecutive patients undergoing cardiac catheterization for AS, the pressure crossover induced a clinically important overestimation of the ⌬P from ϩ22 to ϩ50%. Errors in AVA estimation were considerably smaller (Ϫ2% to ϩ6%) because of simultaneous and offsetting errors in the measurements of ⌬P and flow. Conclusions-The aortic incisura and not the second pressure crossover should be used to obtain invasive indices of AS.
Assessment of Aortic Valve Stenosis Severity : A New Index Based on the Energy Loss Concept
Circulation, 2000
Background —Fluid energy loss across stenotic aortic valves is influenced by factors other than the valve effective orifice area (EOA). We propose a new index that will provide a more accurate estimate of this energy loss. Methods and Results —An experimental model was designed to measure EOA and energy loss in 2 fixed stenoses and 7 bioprosthetic valves for different flow rates and 2 different aortic sizes (25 and 38 mm). The results showed that the relationship between EOA and energy loss is influenced by both flow rate and aortic cross-sectional area (A A ) and that the energy loss is systematically higher (15±2%) in the large aorta. The coefficient (EOA×A A )/(A A −EOA) accurately predicted the energy loss in all situations ( r 2 =0.98). This coefficient is more closely related to the increase in left ventricular workload than EOA. To account for varying flow rates, the coefficient was indexed for body surface area in a retrospective study of 138 patients with moderate or severe...
Impact of blood pressure on the Doppler echocardiographic assessment of severity of aortic stenosis
Heart, 2007
To investigate the impact of blood pressure (BP) on the Doppler echocardiographic (Doppler-echo) evaluation of severity of aortic stenosis (AS). Methods: Handgrip exercise or phenylephrine infusion was used to increase BP in 22 patients with AS. Indices of AS severity (mean pressure gradient (DP mean), aortic valve area (AVA), valve resistance, percentage left ventricular stroke work loss (% LVSW loss) and the energy loss coefficient (ELCo)) were measured at baseline, peak BP intervention and recovery. Results: From baseline to peak intervention, mean (SD) BP increased (99 (8) vs 121 (10) mm Hg, p,0.001), systemic vascular resistance (SVR) increased (1294 (264) vs 1552 (372) dyne6s/cm 5 , p,0.001) and mean (SD) transvalvular flow rate (Q mean) decreased (323 (67) vs 306 (66) ml/s, p = 0.02). There was no change in DP mean (36 (13) vs 36 (14) mm Hg, p = NS). However, there was a decrease in AVA (1.15 (0.32) vs 1.09 (0.33) cm 2 , p = 0.02) and ELCo (1.32 (0.40) vs 1.24 (0.42) cm 2 , p = 0.04), and an increase in valve resistance (153 (63) vs 164 (74) dyne6s/cm 5 , p = 0.02), suggesting a more severe valve stenosis. In contrast, % LVSW loss decreased (19.8 (6) vs 16.5 (6)%, p,0.001), suggesting a less severe valve stenosis. There was an inverse relationship between the change in mean BP and AVA (r =-0.34, p = 0.02); however, only the change in Q mean was an independent predictor of the change in AVA (r = 0.81, p,0.001). Conclusions: Acute BP elevation due to increased SVR can affect the Doppler-echo evaluation of AS severity. However, the impact of BP on the assessment of AS severity depends primarily on the associated change in Q mean , rather than on an independent effect of SVR or arterial compliance, and can result in a valve appearing either more or less stenotic depending on the direction and magnitude of the change in Q mean .
Journal of Cardiovascular Magnetic Resonance, 2011
Background: The effective orifice area (EOA) estimated by transthoracic Doppler echocardiography (TTE) via the continuity equation is commonly used to determine the severity of aortic stenosis (AS). However, there are often discrepancies between TTE-derived EOA and invasive indices of stenosis, thus raising uncertainty about actual definite severity. Cardiovascular magnetic resonance (CMR) has emerged as an alternative method for non-invasive estimation of valve EOA. The objective of this study was to assess the concordance between TTE and CMR for the estimation of valve EOA. Methods and results: 31 patients with mild to severe AS (EOA range: 0.72 to 1.73 cm 2 ) and seven healthy control subjects with normal transvalvular flow rate underwent TTE and velocity-encoded CMR. Valve EOA was calculated by the continuity equation. CMR revealed that the left ventricular outflow tract (LVOT) cross-section is typically oval and not circular. As a consequence, TTE underestimated the LVOT cross-sectional area (A LVOT , 3.84 ± 0.80 cm 2 ) compared to CMR (4.78 ± 1.05 cm 2 ). On the other hand, TTE overestimated the LVOT velocity-time integral (VTI LVOT : 21 ± 4 vs. 15 ± 4 cm). Good concordance was observed between TTE and CMR for estimation of aortic jet VTI (61 ± 22 vs. 57 ± 20 cm). Overall, there was a good correlation and concordance between TTEderived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm 2 , r = 0.92, bias = 0.06 ± 0.29 cm 2 ). The intra-and inter-observer variability of TTE-derived EOA was 5 ± 5% and 9 ± 5%, respectively, compared to 2 ± 1% and 7 ± 5% for CMR-derived EOA.
Discrepancies between direct catheter and echocardiography-based values in aortic stenosis
Catheterization and cardiovascular interventions : official journal of the Society for Cardiac Angiography & Interventions, 2015
The goal of this article is to examine the correlation of catheter (cath) based and echocardiographic assessment of aortic stenosis (AS) in a community-based academic hospital setting, particularly in the degree that decision to refer for surgery is altered. Current guidelines discourage AS evaluation by invasive pressure measurement if echocardiography (echo) is adequate, but several studies show sizable differences between echo and cardiac catheterization lab (CCL) measurements. We examine this correlation using high quality CCL techniques. Sequential patients with suspected AS by echo (n = 40) aged 61-94 underwent catheterization with pressure gradients via left ventricular pressure wire and ascending aorta catheter. The echos leading to the catheterization were independently reviewed by an expert panel to assess the quality of community-based readings. CCL changed assessment of severity of aortic valve area (AVA) by more than 0.3 cm(2) in 25% and 0.5 cm(2) in 8%. Values changed ...
Journal of the American Society of Echocardiography, 2004
The effective orifice area (EOA) is the standard parameter for the clinical assessment of aortic stenosis severity. It has been reported that EOA measured by Doppler echocardiography does not necessarily provide an accurate estimate of the crosssectional area of the flow jet at the vena contracta, especially at low flow rates. The objective of this study was to test the validity of the Doppler-derived EOA. Methods: Triangular and circular orifice plates, funnels, and bioprosthetic valves were inserted into an in vitro aortic flow model and were studied under different physiologic flow rates corresponding to cardiac outputs varying from 1.5 to 7 L/min. For each experiment, the EOA was measured by Doppler and compared with the catheter-derived EOA and with the EOA derived from a theoretic formula. In bioprostheses, the geometric orifice area (GOA) was estimated from images acquired by high-speed video recording. Results: There was no significant difference between the EOA derived from the 3 methods with the rigid orifices (Doppler vs catheter: y ؍ 0.97x ؉0.18 mm 2 , r 2 ؍ 0.98; Doppler vs theory: y ؍ 1.00x ؊3.60 mm 2 , r 2 ؍ 0.99). Doppler EOA was not significantly influenced by the flow rate in rigid orifices. As predicted by theory, the average contraction coefficient (EOA/GOA) was around 0.6 in the orifice plates and around 1.0 in the funnels. In the bioprosthetic valves, both EOA and GOA increased with increasing flow rate whereas contraction coefficient was almost constant with an average value of 0.99. There was also a very good concordance between EOA and GOA (y ؍ 0.94x ؉0.05 mm 2 , r 2 ؍ 0.88). Conclusions: In rigid aortic stenosis, the Doppler EOA is much less flow dependent than generally assumed. Indeed, it depends mainly on the GOA and the inflow shape (flat vs funnel-shaped) of the stenosis. The flow dependence of Doppler EOA observed in clinical studies is likely a result of a variation of the valve GOA or of the valve inflow shape and not an inherent flow dependence of the EOA derived by the continuity equation. (J Am Soc Echocardiogr 2004;17:756-65.)