Introduction. * Corresponding author. Tel: þ ; fax: þ address:

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1 European Journal of Echocardiography (2009) 10, doi: /ejechocard/jen301 Usefulness of the right parasternal view and non-imaging continuous-wave Doppler transducer for the evaluation of the severity of aortic stenosis in the modern area Caroline Cueff de Monchy 1,LaurentLepage 1, Isabelle Boutron 2, Mohamed Leye 1, Delphine Detaint 1, Fabien Hyafil 1, Eric Brochet 1, Bernard Iung 1, Alec Vahanian 1, and David Messika-Zeitoun 1,3 * 1 AP-HP, Cardiology Department, Bichat Hospital, 46 rue Henri Huchard, Paris, France; 2 AP-HP, Département d Epidémiologie Biostatistique et Recherche Clinique, Bichat Hospital, Paris, France; and 3 INSERM, U698, University Paris 7, Paris, France Received 23 August 2008; accepted after revision 17 October 2008; online publish-ahead-of-print 25 November 2008 KEYWORDS Aortic stenosis; Echocardiography; Continuous-wave Doppler Aims Evaluation of the severity of the aortic stenosis (AS) is based on echocardiographic assessment of peak velocity/mean transaortic pressure gradient (MPG) by continuous-wave Doppler and calculation of the aortic valve area (AVA) using the continuity equation. Pioneering echocardiographic studies have shown that MPG should be measured from the apical and right parasternal views using non-imaging continuous-wave Doppler transducer (NI-CWD). Nowadays, ultrasound systems are often sold without NI-CWD due, at least partially, to the improvement of two-dimensional continuous-wave Doppler transducers (2D-CWD). Whether this evolution translated into misevaluation of AS severity was uncertain. Our aim was to evaluate the additional diagnostic value of the use of NI-CWD and the right parasternal view for the evaluation of AS severity in the modern area. Methods and results We prospectively evaluated MPG and AVA using the 2D-CWD (apical view) and the NI-CWD (right parasternal view) in 100 patients ( years, 65% male) consecutively enrolled in an ongoing prospective study. Aortic stenosis severity was graded as mild (AVA 1.5 cm 2 ), moderate (1 1.5 cm 2 ), or severe (AVA, 1cm 2 ). Misclassification was defined as at least a one grade difference and DAVA cm 2 (twice the intra-observer variability). Feasibility of the 2D-CWD was 100%, MPG mmhg, and AVA cm 2. Fifty-three per cent had a mild AS, 34% a moderate AS, and 13% a severe AS. Using the NI-CWD, feasibility was 85%, MPG mmhg, AVA cm 2 (both P, compared with 2D-CWD). Thirty-five per cent (n = 30) had a mild AS, 46% (n = 39) a moderate AS, and 19% (n = 16) a severe AS. Using only the 2D-CWD and the apical view, 21 patients (21%) would have been misclassified: 17 as mild instead of moderate AS and 4 as moderate instead of severe AS. In those misclassified patients, MPG was mmhg higher with the NI-CWD and 33% had an MPG difference.10 mmhg. Conclusion The use of the NI-CWD and the right parasternal view must be performed to evaluate AS severity, especially in case of discrepancy between symptoms and AS severity or for precise evaluation of AS progression. Introduction Aortic valve stenosis (AS) is the third most common cardiovascular disorder in Western Europe and its prevalence is going to dramatically increase with ageing of the population. 1 Management of patients with AS relies on accurate * Corresponding author. Tel: þ ; fax: þ address: david.messika-zeitoun@bch.aphp.fr assessment of symptoms status, AS severity, and left ventricular ejection fraction. 2,3 Echocardiography is the clinical standard to evaluate AS severity. 4 Basic haemodynamic parameters include peak aortic velocity, mean transaortic pressure gradient (MPG), and calculation of the aortic valve area (AVA) using the continuity equation. All of these parameters have been well validated compared with invasive data 5,6 and are major predictors of outcome. 7,8 Severe AS is defined as an Published on behalf of the European Society of Cardiology. All rights reserved. & The Author For permissions please journals.permissions@oxfordjournals.org.

2 Usefulness of the right parasternal view 421 AVA,1cm 2 (or 0.6 cm 2 /m 2 of body surface area), an MPG.40 or 50 mmhg, or a peak aortic velocity.4.0 m/s. 2,3 Pioneering studies have shown that MPG and peak aortic velocity should be assessed using non-imaging continuouswave Doppler transducer (Crystal or Pedof Probe, NI-CWD) in multiple views, especially the apical and right parasternal views. 9 It subtlety allows an optimal alignment with the transaortic valvular jet and to record the highest velocities avoiding misevaluation of AS severity, whereas twodimensional continuous-wave Doppler transducers (2D-CWD) mostly allow recording of velocities and gradients from the apical view. Nowadays, with the improvement of the ultrasound systems (improvement of the signal-to-noise ratio of modern 2D-CWD and probes miniaturization), and with the reduction of time dedicated to echocardiography, the NI-CWD and the right parasternal view are less commonly performed in routine practice. The impact of the exclusive use of the 2D-CWD to evaluate AS severity in the modern area had not been evaluated. We measured the MPG, peak aortic velocity, and the AVA using the NI-CWD and the 2D-CWD in the apical and right parasternal incidence in 100 patients consecutively enrolled in an ongoing prospective study on AS progression. Materials and methods Population In November 2006, we initiated a prospective observational study (COFRASA clinicaltrial.gov NCT ) aiming at evaluating the determinants of AS progression. Inclusion criteria were patients (i) asymptomatic, (ii) of age 70 years, and (iii) with at least mild AS defined by an MPG 10 mmhg. Exclusion criteria were (i) aortic regurgitation of grade.2/4, (ii) associated valve disease of grade.2/4, (iii) chronic renal failure (clearance of the creatinine 30 ml/min) because AS progression is mainly influenced by calcium phosphorus product changes, and (iv) left ventricular outflow tract (LVOT) obstruction. Coronary artery disease was not an exclusion criterion. Echocardiography All patients underwent a comprehensive echocardiography performed by an experienced echocardiographer (D.M.-Z., more than 500 transthoracic echocardiography per year) using high quality commercially available ultrasound systems (IE33, Philips, Andover, MA, USA and Vivid 7, GE, Horten, Norway). Left ventricular outflow tract diameter was measured in midsystole from the parasternal long-axis view using the zoom at the insertion of the leaflets. Left ventricular outflow tract time velocity integral (TVI LVOT ) was recorded with pulsed Doppler from the apical five-chamber view just proximal to the valve orifice. Peak aortic valve velocity, aortic valve TVI (TVI AO ), and MPG were measured during the same examination (i) from the five-chamber apical view with the 2D-CWD and (ii) from the right parasternal view using the NI-CWD. From both views, care was given to obtain a parallel intercept angle between the ultrasound beam and the aortic jet. 9,10 Three to five measurements were averaged. The AVA was calculated using the continuity equation: AVA ¼ p 4 ðlvot diameterþ2 TVI LVOT TVI AO : Aortic stenosis severity was graded as recommended by the current guidelines 3 as mild if the AVA was 1.5 cm 2, moderate between 1 and 1.5 cm 2, and severe if the AVA was,1 cm 2. Statistical analysis Continuous variables are expressed as mean + standard deviation. Comparison of peak aortic velocity, MPG, and AVA obtained by the two approaches was performed using a paired t-test. Misclassification was defined as a grade difference between the apical and the right parasternal views. P, 0.05 was considered statistically significant. Results Population One hundred patients were prospectively and consecutively enrolled from November 2006 to April Mean age was years and 66% were male. All patients were asymptomatic and 91% were in sinus rhythm. Mean LVOT diameter was mm. Using the view providing the highest velocities and gradients, MPG was mmhg and peak aortic valve velocity m/s. Mean AVA was cm 2 with a wide range of AS severity ( cm 2 ). Aortic stenosis was graded as mild (AVA 1.5 cm 2 ) in 33%, moderate (AVA between 1 and 1.5 cm 2 )in 48%, and severe (AVA, 1cm 2 ) in 19%. Intra-observer variability measured in 15 patients was cm 2. Mean left ventricular ejection fraction was %. Echocardiographic evaluation of aortic stenosis severity Apical approach with two-dimensional continuous-wave Doppler Feasibility of MPG and peak aortic valve velocity measurements was 100%. Mean transaortic pressure gradient was mmhg, peak aortic valve velocity m/s, and AVA cm 2 (Table 1). Aortic stenosis was graded as mild in 53%, moderate in 34%, and severe in 13%. Right parasternal approach with non-imaging continuous-wave Doppler In 15 patients, the right parasternal view was not feasible. Mean transaortic pressure gradient and peak aortic valve Table 1 Peak aortic velocities, mean transaortic pressure gradient, and aortic valve area using the highest recorded velocities, the steerable transducer (apical view) and the crystal or Pedof probe (right parasternal view) Highest recorded Apical view Right parasternal view P between views Peak aortic velocity (m/s) MPG (mmhg) , AVA (cm) , MPG, mean transaortic pressure gradient; AVA, aortic valve area.

3 422 C.C. de Monchy et al. velocity were significantly higher and AVA significantly smaller using the NI-CWD than using the 2D-CWD ( mmhg, m/s, and cm 2, respectively, all P, 0.005) (Table 1). Using the NI-CWD and the right parasternal view, 30 patients (35%) had a mild AS, 39 patients (46%) a moderate AS, and 16 patients (19%) a severe AS. Using only the 2D-CWD and the apical view, 26 patients (26%) would have been misclassified (Table 2). Using a more stringent criteria for misclassification, at least one grade difference between the 2 views and an AVA difference 0.15 cm 2 (twice the standard deviation of the intra-observer variability), 21 patients (21%) would have been misclassified: 17 as mild instead of moderate AS and 4 as moderate instead of severe AS (Figure 1). In those 21 misclassified patients, MPG was mmhg higher with the NI-CWD and 7 patients (33%) had an MPG difference.10 mmhg. Exclusion of patients in atrial fibrillation or grading AS severity according to peak velocity or mean gradient did not significantly affect our results. Discussion The present study clearly demonstrates that not using NI-CWD and the right parasternal view leads to a significant underestimation of AS severity in one-fifth of patients. Management of patients with AS relies on accurate assessment of AS severity. 2,3 The clinical utility of measuring the stenosis severity is three-fold: to ensure that the valve disease is the cause of the patient s symptoms, to reliably predict the optimal timing of valve replacement, and to schedule the frequency of follow-up visits to the physician. Current guidelines define AS as being severe if the AVA is,1cm 2 (or 0.6 cm 2 /m 2 of body surface area), MPG.40 or 50 mmhg, or maximum aortic velocity.4.0 m/s. Since the use of catheterization in AS is rare nowadays (and potentially deleterious), echocardiography is the key diagnostic tool to evaluate AS severity. 3 Echocardiographic pitfalls and errors have been well described in pioneering echocardiographic studies Doppler evaluation of AS severity requires attention to technical details, with the most common error being underestimation of disease severity due to a non-parallel intercept angle between the ultrasound beam of continuous-wave Doppler and the high-velocity jet through the narrowed valve. 2 Therefore, Table 2 Severity of the aortic stenosis based on the valve area obtained using the two-dimensional continuous-wave Doppler transducer (apical view) and the non-imaging continuous-wave Doppler transducer (right parasternal view) Apical view Right parasternal view Mild AS Moderate AS Severe AS n Mild AS Moderate AS Severe AS n In bold patients misclassified using only the two-dimensional continuous-wave Doppler transducer. AS, aortic stenosis; n, number of patients. use of a dedicated NI-CWD transducer (Crystal or Pedof probe) in multiple views was strongly recommended. At the present time, with the improvement of the quality of the ultrasound systems, the miniaturization of combined imaging and Doppler transducers, and with the reduction of time dedicated to each echocardiography, measurements of peak aortic velocity and MPG are often performed only using the 2D-CWD in the apical view. Even more critical, echo machines are often sold without crystal probe. Whether these changes in our routine practice impacted the evaluation of AS severity was unknown. In a large series of consecutive patients with a wide range of AS severity enrolled in an ongoing prospective study, we compared the evaluation of AS severity (MPG, peak aortic velocity, and AVA) using the NI-CWD and the 2D-CWD in the apical and right parasternal incidence. Using stringent criteria, 20% of patients would have been misclassified using only the 2D-CWD and the apical view. Therefore, for the evaluation of AS severity, use of NI-CWD and the right parasternal view has an important additional diagnostic value and should be systematically performed in routine practice even in the modern area. On the other way, it is important to emphasize that NI-CWD should be used in addition and not in place of 2D-CWD, because it is not feasible in 15% and leaded to misclassification of AS severity in 5 additional patients. Our results may have important clinical implications for clinical decision-making (surgical indications and schedule for follow-up visits under conservative management). In addition, rapid AS progression is a class IIa indication for surgery according to current guidelines. 3 Using the right parasternal windows, and comparing to results from a previous examination where only an apical window was used, may give the false impression of rapid progression. For the reliability and constancy of the evaluation of AS progression, using the multiple views is mandatory and it is crucial to specify on the echo report from which window the highest velocity is recorded. The present study deserves several comments. First, measurements using the 2D-CWD and NI-CWD were not performed blindly and we could not definitively differentiate the respective additional value of the transducer and the incidence. However, our aim was not to favour one or the other incidence but to record the highest peak velocities and mean gradient and the same consistent systematic protocol was used which reflects the typical clinical scenario. Aortic stenosis jet was first interrogated from the apical window using the 2D-CWD, then using the NI-CWD from the right parasternal view. Furthermore, Doppler interrogation was performed in 20 patients from the apical view using both transducers, and NI-CWD was not superior. Secondly, measurements using the NI-CWD require an additional time (5 min with training). However, in regard to its additional value, this should not be considered as a limitation. Thirdly, we also tested the other incidences, namely the suprasternal and subcostal views, using the NI-CWD. We did not observe any misclassification using the subcostal view and only one with the suprasternal view. Fourthly, only patients 70 years or older, with mainly degenerative tricuspid AS, were enrolled in the present study. Whether NI-CWD and the right parasternal view provide the same additional value in younger patients with a higher incidence of bicuspid aortic valve deserve further studies. Finally, we defined misclassification as a grade difference between the apical and

4 Usefulness of the right parasternal view 423 Figure 1 Example of misclassified patients using only the two-dimensional continuous-wave Doppler and the apical view (left) and not the non-imaging continuous-wave Doppler and the right parasternal view (right). 2D-CWD, two-dimensional continuous-wave Doppler; NI-CWD, non-imaging continuous-wave Doppler; AS, aortic stenosis; AVA, aortic valve area; MGP, mean transaortic pressure gradient; Peak V, peak aortic velocity; Ao TVI, aortic time velocity integral. the right parasternal views and an AVA difference 0.15 cm 2. This threshold was based on our intra-observer variability (twice the standard deviation). However, use of slightly different threshold does not change our conclusions (19 patients misclassified with a 0.20 cm 2 threshold). Conclusion In the present study, we demonstrate that, even in the modern area using sophisticated ultrasound systems, NI-CWD and the right parasternal view have an important diagnostic value and should be performed for a precise evaluation of AS severity. These results may have important clinical implications such as to ensure that the valve disease is the cause of the patient s symptoms, to reliably predict the optimal timing of valve replacement, and to schedule the frequency of follow-up visits to the physician. Acknowledgements The authors thank Dr Xavier Duval and all the team of the center of clinical investigation (CIC) for their precious help. Conflict of interest: none declared. Funding C.C.M. was supported by a grant from the Fédération Française de Cardiologie and D.M.-Z. by a contrat d interface INSERM. The COFRASA study is supported by a grant from the Assistance Publique Hôpitaux de Paris (PHRC National 2005). References 1. Iung B, Baron G, Butchart EG, Delahaye F, Gohlke-Barwolf C, Levang OW et al. A prospective survey of patients with valvular heart disease in Europe: The Euro Heart Survey on Valvular Heart Disease. Eur Heart J 2003;24: Bonow RO, Carabello BA, Kanu C, de Leon AC Jr, Faxon DP, Freed MD et al. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 1998 guidelines for the management of patients with valvular heart disease): developed in collaboration with the Society of Cardiovascular Anesthesiologists: endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons. Circulation 2006;114:e Vahanian A, Baumgartner H, Bax J, Butchart E, Dion R, Filippatos G et al. Guidelines on the management of valvular heart disease: The Task Force on the Management of Valvular Heart Disease of the European Society of Cardiology. Eur Heart J 2007;28: Otto CM. Valvular aortic stenosis: disease severity and timing of intervention. J Am Coll Cardiol 2006;47: Currie PJ, Seward JB, Reeder GS, Vlietstra RE, Bresnahan DR, Bresnahan JF et al. Continuous-wave Doppler echocardiographic assessment of severity of calcific aortic stenosis: a simultaneous Doppler-catheter correlative study in 100 adult patients. Circulation 1985;71: Teirstein P, Yeager M, Yock PG, Popp RL. Doppler echocardiographic measurement of aortic valve area in aortic stenosis: a noninvasive application of the Gorlin formula. J Am Coll Cardiol 1986;8: Otto CM, Burwash IG, Legget ME, Munt BI, Fujioka M, Healy NL et al. Prospective study of asymptomatic valvular aortic stenosis. Clinical, echocardiographic, and exercise predictors of outcome. Circulation 1997;95: Pellikka PA, Sarano ME, Nishimura RA, Malouf JF, Bailey KR, Scott CG et al. Outcome of 622 adults with asymptomatic, hemodynamically

5 424 C.C. de Monchy et al. significant aortic stenosis during prolonged follow-up. Circulation 2005; 111: Williams GA, Labovitz AJ, Nelson JG, Kennedy HL. Value of multiple echocardiographic views in the evaluation of aortic stenosis in adults by continuous-wave Doppler. Am J Cardiol 1985;55: Agatston AS, Chengot M, Rao A, Hildner F, Samet P. Doppler diagnosis of valvular aortic stenosis in patients over 60 years of age. Am J Cardiol 1985;56: Jaffe WM, Dewhurst TA, Otto CM, Pearlman AS. Influence of Doppler sample volume location on ventricular filling velocities. Am J Cardiol 1991;68: Otto CM, Nishimura RA, Davis KB, Kisslo KB, Bashore TM. Doppler echocardiographic findings in adults with severe symptomatic valvular aortic stenosis. Balloon Valvuloplasty Registry Echocardiographers. Am J Cardiol 1991;68: