Assessment Of Aortic Stenosis Severity Research Articles

NON-INVASIVE ASSESSMENT OF CENTRAL AORTIC PRESSURE, AORTIC FLOW AND VASCULAR LOAD IN PATIENTS WITH AORTIC STENOSIS BEFORE AND AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT

Objective: The left ventricle (LV) faces a dual afterload in patients with aortic stenosis (AS), both from the narrowed valve and age-related arterial stiffening. Variability in indices of AS severity assessment suggests an inter-relationship of the valvular pressure gradient on systemic arterial pressure and flow. Our study aims to evaluate the dynamic vascular load (VL) non-invasively in AS patients before and after transcatheter aortic valve replacement (TAVR) using the approach of simultaneous cardiac magnetic resonance (CMR) and radial applanation tonometry (AT). Design and method: Ascending aortic pressure, flow and VL were measured in 3 patients at baseline and post-TAVR using a previously reported simultaneous CMR/AT technique. CMR provided aortic flow, and radial AT waves were converted offline to aortic pressure using SphygmoCor 8.1 (AtCor Medical) and calibrated using brachial cuff values. VL was determined as the relationship of derived aortic pressure to CMR aortic flow velocity, by calculating the average modulus of pressure divided by flow. Following the acquisition of post TAVR data, 300 micrograms of sublingual nitroglycerine (GTN) was introduced to investigate the effect on changing vascular load. Results: At 38 ± 3 days post TAVR, mean aortic pressure (MP) and mean systolic flow (MF) both increased (100 ± 17 pre, 109 ± 12 post, mmHg; 178 ± 44 pre, 230 ± 74 post, ml/s). Following GTN administration, MP (95 ± 3 mmHg) decreased but not MF (228 ± 57 ml/s) – see figure. The steady state systemic vascular resistance (SVR) reduced post TAVR (22501 ± 5929 pre, 20484 ± 6232 post, dynes.s/cm3), but not VL (1082 ± 219 pre, 1111 ± 483 post, dynes.s/cm3). Conversely, GTN administration significantly reduced VL (838 ± 295 dynes.s/cm3) with little effect on SVR (19313 ± 5631 dynes.s/cm3). Conclusions: Our study demonstrates that our novel technique can be reliably replicated in patients to evaluate the changes to aortic pressure, flow and VL before and after TAVR. VL appears to be a dynamic measurement of vascular stiffness independent of AS and may prove to be a useful measure to predict haemodynamic responses and ventriculo-arterial coupling in AS patients post TAVR. Larger longitudinal cohort studies are warranted.

Comprehensive assessment of the aortic valve in critically ill patients for the non-cardiologist. Part I: Aortic stenosis of the native valve.

Aortic stenosis (AS) causes left ventricular outflow obstruction. Severe AS has major haemodynamic implications in critically ill patients, in whom increased cardiac output and oxygen delivery are often required. Transthoracic echocardiography (TTE) plays akey role in the AS severity grading. In this review, we will give an overview of how to use the simplified Bernoulli equation to convert the echo Doppler measured velocities (cm s-1) to AS peak and mean gra-dient (mm Hg) and how to calculate the aortic valve area (AVA), using the continuity equation, based on the principle of preservation of flow. TTE allows quantification of compensatory left ventricular (LV) hypertrophy, assessment of LV systolic function, and determination of LV diastolic function and LV loading. Subsequently, the obtained results from the TTE study need to be integrated to establish the AS severity grading. The pitfalls of echocardiographic AS severity assessment are explained, and how to deal with inconsistency between AVA and mean gradient. The contribution of transoesophageal echocardiography, low-dose dobutamine stress echo (in case of low-flow low-gradient AS), echocardiography strain imaging, cardiac magnetic resonance imaging, cardiac multidetector computed tomography and the relatively new concept of Flow Pressure Gradient Classification to the work-up for aortic stenosis is discussed. Finally, the treatment of AS is overviewed. Elective aortic valve replacement is indicated in patients with severe symptomatic AS. In the ICU, afterload reduction by vasodilator therapy and treatment of pulmonary and venous congestion by diuretics could be considered.

The five-beat averaged method of assessing aortic stenosis in atrial fibrillation significantly underestimates stenosis severity compared to sinus rhythm

Abstract Background Doppler echocardiographic assessment of aortic stenosis (AS) is dependent on trans-valvular flow rate (TVFR) and is most accurately performed in physiologically normal conditions (TVFR >200ml/s). Atrial fibrillation (AF) complicates AS assessment with heart rate variability and reduced averaged indexed stroke volume (SVi) compared to sinus rhythm (SR). We hypothesize that the 5-beat averaging technique in AF leads to underestimation of severity of AS compared to SR, and that diagnostic accuracy may be improved by maximum SVi beat selection. Methods Patients with at least mild AS (mean aortic gradient (MG) >15mmHg) with separate echocardiograms demonstrating SR and AF within a six-month period were identified. Patients with interval cardiac surgery, change in left ventricular ejection fraction (LVEF) of >15%, aortic valve prostheses, infective endocarditis, paced rhythm, severe concomitant valvular dysfunction, LVEF <35%, heart rate >100 beats per minute (bpm) or TVFR <200ml/s on their SR examination were excluded. In AF, individual beat SVi was calculated from individual beat aortic velocity time integral (VTI) and the reported aortic valve area (AVA) via the continuity equation. Results Seventeen patients were identified (mean time between echocardiograms 132 days, mean difference in LVEF 4%, mean difference in heart rate 11bpm). Using the 5-beat averaged model, compared to SR, the presence of AF significantly reduced SVi (−12.68ml/m2, p=0.00007) and TVFR (−69ml/s, p=0.00014). In AF, 9/17 cases demonstrated one or more beats with TVFR <200ml/s, with 6/17 producing a 5-beat averaged TVFR <200ml/s – consistent with a low flow state. Correspondingly, flow derived severity assessment parameters and calculated aortic valve area (AVA) in AF were reduced compared to SR (aortic peak velocity (Vmax) −0.42m/s, p=0.00005, MG −7.01mmHg, p=0.002, AVA −0.11cm2, p=0.025). As a proposed correction in AF, the single beat with the largest SVi was compared with SR. This measure improved concordance with flow conditions and severity assessment in SR (difference SVi −8.77ml/m2, p=0.004, TVFR −46ml/s, p=0.001, Vmax −0.21, p=0.003, MG −3.55mmHg, p=0.02) and equalized calculated AVA (−0.07cm2, p=0.09). Conclusion In individual patients with AS observed in SR and AF within a six-month period, AF was associated with significantly lower SVi and TVFR, with underestimation of AS severity assessment. AS assessment in AF using maximum observed stroke volume beat (as opposed to 5-beat average) improves concordance with SR assessment significantly. Funding Acknowledgement Type of funding source: None

Computed tomography aortic valve calcium scoring for the assessment of aortic stenosis progression

ObjectiveCT quantification of aortic valve calcification (CT-AVC) is useful in the assessment of aortic stenosis severity. Our objective was to assess its ability to track aortic stenosis progression compared with...

\u201cPure\u201d severe aortic stenosis without concomitant valvular heart diseases: echocardiographic and pathophysiological features

PurposeIn echocardiography the severity of aortic stenosis (AS) is defined by effective orifice area (EOA), mean pressure gradient (mPGAV) and transvalvular flow velocity (maxVAV). The hypothesis of the present study was to confirm the pathophysiological presence of combined left ventricular hypertrophy (LVH), diastolic dysfunction (DD) and pulmonary artery hypertension (PAH) in patients with “pure” severe AS.Methods and ResultsPatients (n = 306) with asymptomatic (n = 133) and symptomatic (n = 173) “pure” severe AS (mean age 78 ± 9.5 years) defined by indexed EOA < 0.6 cm2 were enrolled between 2014 and 2016. AS patients were divided into 4 subgroups according to mPGAV and indexed left ventricular stroke volume: low flow (LF) low gradient (LG)-AS (n = 133), normal flow (NF) LG-AS (n = 91), LF high gradient (HG)-AS (n = 21) and NFHG-AS (n = 61). Patients with “pure” severe AS showed mean mPGAV of 31.7 ± 9.1 mmHg and mean maxVAV of 3.8 ± 0.6 m/s. Only 131 of 306 patients (43%) exhibited mPGAV > 40 mmHg and maxVAV > 4 m/s documenting incongruencies of the AS severity assessment by Doppler echocardiography. LVH was documented in 81%, DD in 76% and PAH in 80% of AS patients. 54% of “pure” AS patients exhibited all three alterations. Ranges of mPGAV and maxVAV were higher in patients with all three alterations compared to patients with less than three. 224 (73%) patients presented LG-conditions and 82 (27%) HG-conditions. LVH was predominant in NF-AS (p = 0.014) and PAH in LFHG-AS (p = 0.014). Patients’ treatment was retrospectively assessed (surgery: n = 100, TAVI: n = 48, optimal medical treatment: n = 156).ConclusionIn patients with “pure” AS according to current guidelines the presence of combined LVH, DD and PAH as accepted pathophysiological sequelae of severe AS cannot be confirmed. Probably, the detection of these secondary cardiac alterations might improve the diagnostic algorithm to avoid overestimation of AS severity.

Assessment of Aortic Stenosis Severity: A Multimodality Approach.

Severe aortic stenosis (AS) is associated with a progressive cardiac remodeling that ultimately leads to heart failure and death if the valve is not replaced. The confirmation of AS severity is therefore crucial to adequately manage patients with AS. Transthoracic echocardiography is the first-line examination to confirm AS severity, but it may be inconclusive in discordant cases. In this setting, AS severity should be confirmed using a multimodality imaging approach. This review gives an overview of how to assess and/or confirm AS severity, especially in case of discordance.

P1366 Low-flow, low-gradient severe aortic stenosis: might mitral regurgitation be a culprit?

Abstract Introduction According to current guidelines, given a patient with low-gradient (aortic valve maximum velocity &amp;lt; 4m/s and/or aortic valve mean gradient &amp;lt;40mmHg), aortic valve area (AVA) &amp;lt; 1cm2 and low-flow (stroke volume (SV) &amp;lt; 35mL/min/m2), with preserved left ventricle function (ejection fraction (EF) ≥50%), an integrated approach for assessment of aortic stenosis severity is proposed. We aimed to investigate whether mitral regurgitation can play a role in those cases, possibly being responsible for low antegrade systolic flow. Methods We retrospectively analysed 121 consecutive transthoracic echocardiograms (TTEs) of patients with severe aortic stenosis, with AVA &amp;lt; 1.0cm2 as assessed by continuity equation. Patients with low ejection fraction (&amp;lt; 50%) were excluded. We therefore included 84 patients (females 53,6%, mean age 79,1+-10 years). Stroke volume was assessed by Doppler at the left ventricle outflow tract (LVOT). We then compared the prevalence of more than mild mitral regurgitation among patients with low-gradient and low-flow and the other patients. Results 15 patients had both low-gradient, low-flow and preserved ejection fraction. There was a significant association regarding the presence of more than mild mitral regurgitation among these patients (p = 0.028, OR = 4.7, CI 95% 1.1-20.1). In these patients, it was also observed a higher prevalence of atrial fibrillation (p = 0.03, OR = 6.9, CI 95% 1.74-27.1), lower longitudinal systolic function of right ventricle as measured by TAPSE (16.6 vs 21.5mm, p = 0.028), and a tendency towards higher left atrial volume (113 vs 87mL, p = 0.06). Conclusions Given the findings that the prevalence of more than mild mitral regurgitation is higher in patients with severe aortic stenosis as assessed by AVA with both low-gradient, low-flow and preserved ejection fraction, we suggest that the presence of more than mild mitral regurgitation should be considered on the approach of aortic stenosis classification of these patients.

Combining Automatic Angle Correction and 3-D Tracking Doppler for the Assessment of Aortic Stenosis Severity.

Aortic valve stenosis (AS) is a narrowing of the aortic valve opening, which causes increased load on the left ventricle. Untreated, this condition can eventually lead to heart failure and death. According to current recommendations, an accurate diagnosis of AS mandates the use of multiple acoustic windows to determine the highest velocity. Furthermore, the optimal positioning of both patient and transducer to reduce the beam-to-flow angle is emphasized. Being operator dependent, the beam alignment is a potential source of uncertainty. In this work, we perform noncompounded 3-D plane wave imaging for retrospective estimation of maximum velocities in aortic jets with automatic angle correction. This is achieved by combining a hybrid 3-D speckle tracking method to estimate the jet direction and 3-D tracking Doppler to generate angle-corrected sonograms, using the direction from speckle tracking as input. Results from simulations of flow through an orifice show that 3-D speckle tracking can estimate the jet orientation with acceptable accuracy for signal-to-noise ratios above 10 dB. Results from 12 subjects show that sonograms recorded from a standard apical view using the proposed method yield a maximum velocity that matches continuous wave (CW) Doppler sonograms recorded from the acoustic window with the lowest angle within a ±10% margin, provided that a high enough pulse repetition frequency could be achieved. These results motivate further validation and optimization studies.

Hypertension and transcatheter aortic valve replacement: parallel or series?

Aortic stenosis (AS) is the most common valvular heart disease in the elderly and it causes significant morbidity and mortality. Hypertension is also highly prevalent in elderly patients with AS, and AS patients with hypertension have worse outcomes. Accurate assessment of AS severity and understanding its relationship with arterial compliance has become increasingly important as the options for valve management, particularly transcatheter interventions, have grown. The parameters used for quantifying stenosis severity have traditionally mainly focused on the valve itself. However, AS is now recognized as a systemic disease involving aging ventricles and stiff arteries rather than one limited solely to the valve. Over the last decade, valvuloarterial impedance, a measure of global ventricular load, has contributed to our understanding of the pathophysiology and course of AS in heterogeneous patients, even when segregated by symptoms and severity. This review summarizes our growing understanding of the interplay between ventricle, valve, and vessel, with a particular emphasis on downstream vascular changes after transcatheter aortic valve replacement and the role of valvuloarterial impedance in predicting left ventricular changes and prognosis in patients with various transvalvular flow patterns.

Predicting Outcomes in Patients With AsymptomaticModerate to Severe Aortic Stenosis

Outcomes in asymptomatic patients with aortic stenosis (AS) have been reported primarily from tertiary centers. Whether observations from a community hospital cohort would be similar or if clinical variables would assume a more important role remains uncertain. This retrospective cohort study from one community hospital followed asymptomatic patients with moderate to severe AS for 3years following an index echocardiogram. Patients underwent standard echocardiographic imaging and assessment of AS severity. Outcomes included aortic valve replacement, onset of Class 4 heart failure and cardiovascular death. Inclusion or exclusion criteria were met by 190 patients (body mass index of 30.8 ± 7.5 kg/m2 and age 70.9 ± 13.0 years). In this obese and racially diverse cohort, adverse outcomes occurred in 72 of 190 (38%), aortic valve replacement in 33 of 72 (46%), heart failure in 30 of 72 (42%), and cardiovascular death in 9 of 72 (13%). Univariate analyses found that the echocardiographic variables assessing AS severity (Vmax, mean aortic valve gradient, and the dimensionless index) were strongly associated with outcomes. A model predicting time to adverse outcomes included age, gender, Charlson index, Vmax, aortic valve area, the electrocardiographic variables of atrial fibrillation and left ventricular strain, and echocardiographic variables unrelated to the direct measurements of stenosis severity. In conclusion, direct echocardiographic measures of AS severity, echocardiographic parameters unrelated to AS severity plus the electrocardiographic variables of atrial fibrillation and left ventricular strain were the dominant predictors of adverse outcomes in a community hospital cohort of asymptomatic patients with moderate to severe AS.

Comparison of preoperative and intraoperative assessment of aortic stenosis severity by echocardiography

BackgroundGeneral anaesthesia and surgically induced changes in cardiac loading conditions may alter flow across the aortic valve. This study examined how echocardiographic assessment of the severity of aortic stenosis (AS) changes during surgery. MethodsPatients who underwent aortic valve replacement for any severity of AS between July 2007 and June 2015 were identified. Peak velocities, mean gradients, and dimensionless indices (DI) measured with preoperative transthoracic echocardiography (TTE) were compared with those measured with intraoperative transoesophageal echocardiography (TOE). Additionally, agreement of preoperative and intraoperative grading of AS based on these measurements was assessed. ResultsData from 319 patients were analysed. On average, intraoperative TOE peak velocity and mean gradient were lower by 0.59 m s−1 and 12.5 mm Hg, respectively (P<0.0001), compared with preoperative TTE measurements, whereas the difference in mean DI was minimal at 0.008. Preoperative and intraoperative grades of AS severity (mild, moderate, and severe) by peak velocity, mean gradient, and DI agreed in 53.3, 53.7, and 83.3% of patients, respectively. The TOE grade of AS severity by peak velocity and mean gradient was at least one lower than the TTE grade in 45.1 and 42.7% of patients, respectively. Significantly fewer patients had their severity of AS reclassified based on DI (P<0.0001). ConclusionsIntraoperative TOE peak velocities and mean gradients are often significantly lower than preoperative TTE measurements, leading to underestimation of AS severity in nearly half of our study patients. The DI is a more reliable measurement of AS severity in the intraoperative setting.

Usefulness of 3-Tesla cardiac magnetic resonance imaging in the assessment of aortic stenosis severity in routine clinical practice

Recently, 1.5-Tesla cardiac magnetic resonance imaging (CMR) was reported to provide a reliable alternative to transthoracic echocardiography (TTE) for the quantification of aortic stenosis (AS) severity. Few data are available using higher magnetic field strength MRI systems in this context. To evaluate the feasibility and reproducibility of the assessment of aortic valve area (AVA) using 3-Tesla CMR in routine clinical practice, and to assess concordance between TTE and CMR for the estimation of AS severity. Ninety-one consecutive patients (60 men; mean age 74±10years) with known AS documented by TTE were included prospectively in the study. All patients underwent comprehensive TTE and CMR examination, including AVA estimation using the TTE continuity equation (0.81±0.18cm2), direct CMR planimetry (CMRp) (0.90±0.22cm2) and CMR using Hakki's formula (CMRhk), a simplified Gorlin formula (0.70±0.19cm2). Although significant agreement with TTE was found for CMRp (r=0.72) and CMRhk (r=0.66), CMRp slightly overestimated (bias=0.11±0.18cm2) and CMRhk slightly underestimated (bias=-0.11±0.17cm2) AVA compared with TTE. Inter- and intraobserver reproducibilities of CMR measurements were excellent (r=0.72 and r=0.74 for CMRp and r=0.88 and r=0.92 for peak aortic velocity, respectively). 3-Tesla CMR is a feasible, radiation-free, reproducible imaging modality for the estimation of severity of AS in routine practice, knowing that CMRp tends to overestimate AVA and CMRhk to underestimate AVA compared with TTE.

Trends in Age at Diagnosis in Individuals with Aortic Stenosis

To the Editor: Aortic stenosis (AS) is the most common valvular disease in elderly adults,1 and its prevalence is expected to grow with the aging of the population.2-5 In the last decade, new therapies have become available for the treatment of symptomatic severe AS in elderly adults in whom the condition is deemed to be inoperable or who are at high risk for surgery,6 which poses significant implications for healthcare systems.7 Data regarding long-term trends in age at diagnosis of AS are scarce, so this study was designed to evaluate these temporal trends, with particular emphasis on individuals with severe AS. Between January 1, 1991, and December 31, 2015, 107,880 individuals aged 18 and older who underwent a first transthoracic echocardiogram within the public health care system of the Area Sanitaria de A Coruña in Spain (2,754 km2, 2013 census: 553,490 residents) and in whom comprehensive data regarding demographic characteristics and AS severity assessment were available were identified. The 25-year period was divided into five quinquennia (1991–1995, 1996–2000, 2001–2005, 2006–2010, 2011–2015), and trends across these epochs were assessed. For the purposes of this study, AS was defined on the basis of a maximal jet velocity of 2 m/s or greater through a native aortic valve and was further classified as mild (maximal jet velocity 2.0–2.9 m/s or mean gradient <20 mmHg), moderate (maximal jet velocity 3.0–3.9 m/s or mean gradient 20–39 mmHg), or severe (maximal jet velocity ≥4 m/s or mean gradient ≥40 mmHg) according to current guidelines.8 Trends over time were tested using the Cuzick nonparametric test for continuous variables and the Cochran–Armitage test for binary categorical variables. The local research ethics committee approved the study. Overall, 18,731 (17.4%) individuals met criteria for AS, including 12,590 (67.2%) with mild, 3,330 (17.8%) with moderate, and 2,811 (15%) with severe AS. Mean age upon referral of individuals with any degree of AS increased gradually and significantly over time (64.9 ± 13.3 in 1991–1995, 69.8 ± 12.0 in 1996–2000, 71.2 ± 11.8 in 2001–2005, 72.6 ± 11.6 in 2006–2010, 74.5 ± 11.8 in 2011–2015; P for trend <.001). These results were consistent in the subset of individuals with severe AS, in whom mean age ranged from 67.3 ± 12.9 in the first quinquennium to 76.8 ± 10.7 in the last (P for trend <.001). The proportion of individuals aged 80 and older also increased gradually from 8.5% to 36.2% in those with any degree of AS and from 12.8% to 45.9% in those with severe AS (P for trend <.001 for both comparisons) (Figure 1). No significant trends in sex were observed; the proportion of male subjects with any degree of AS ranged from 49.9% in 1991–1995 to 50.1% in 2011–2015 (P for trend = .09). In this study, mean age at the time of diagnosis of AS increased gradually by almost 10 years over a period of 25 years, and this finding was consistent in the subset of individuals with severe AS. In particular, the proportion of individuals aged 80 years and older with any degree of AS at the time of diagnosis quadrupled, and the proportion of those aged 80 and older with severe AS tripled. These findings occurred despite greater availability of echocardiography, which would be expected to lead to earlier detection of the disease. The results of this study agree with those recently reported in a study9 that found that, not only age, but also predicted surgical risk of individuals with severe AS referred for echocardiography increased over time. It is likely that progressive aging of the population explains these trends in the burden of AS in elderly adults because degenerative etiology (which correlates with increasing age) remains the most frequent cause of AS.10 Other possible explanations include a progressive decline in the incidence of rheumatic heart disease in industrialized countries in recent decades, and a lower threshold for referring elderly adults with suspected valvular heart disease for echocardiography. In individuals with severe symptomatic AS, older age is associated with greater operative risks and more comorbidities. Given the significant changes in the management of elderly adults with severe AS over the past few years, including the advent of transcatheter aortic valve implantation,6 these results may have substantial implications for healthcare planning. Author Contributions: Bouzas-Mosquera: study concept and design, acquisition of subjects and data, analysis and interpretation of data, preparation of manuscript. Broullón, Álvarez-García, Vázquez-Rodríguez: acquisition of subjects and data, review of manuscript. Sponsor's Role: The study had no external funding.

TRANSSEPTAL CATHETERIZATION FOR THE EVALUATION OF AORTIC STENOSIS IN PATIENTS WITH LOW- AND PRESERVED LEFT VENTRICULAR FUNCTION

Echocardiography is the most common diagnostic modality used in the assessment of aortic stenosis (AS). However, disparity has been noted between invasive and non-invasive evaluation of AS in patients with low-output, low-gradient states. This study attempted to identify the accuracy and agreement of echocardiography in assessment of AS compared with transseptal catheterization in patients with low and preserved left ventricular (LV) systolic function. Baseline, echocardiographic and hemodynamic characteristics from one hundred patients that underwent both echocardiography and transseptal catheterization for assessment of moderate-severe AS was collected. Data from 50 patients with low LV systolic function and 50 age-matched controls with preserved LV systolic function was analysed comparing invasive and non-invasive evaluation of AVA and AS severity classification. Echocardiography had a sensitivity, specificity and diagnostic accuracy of 98%, 100% and 98% respectively for classification of severe AS when compared with transseptal catheterization in patients with preserved LV systolic function. The sensitivity, specificity and diagnostic accuracy of echocardiography was 83%, 44% and 78% in patients with low LV systolic function. Reclassification of AS severity after invasive assessment was significantly more common in patients with low LV systolic function (22% vs. 2%, p=0.038). Bland-Altman analysis suggested better agreement between invasive and non-invasive assessment in patients with preserved rather than low LV systolic function. Amongst patients who underwent AVR, in-hospital mortality was significantly higher in the low LV systolic function cohort (15.4% vs. 2.2%, p=0.038) No major complications were noted with transseptal catheterization. Echocardiography offers an accurate assessment of AS severity in patients with preserved LV systolic function. However, discrepancies exist between echocardiography and transseptal catheterization assessment of AS severity in patients with reduced LV systolic function, suggesting invasive evaluation of AS may be necessary in this patient population.

Measurement of peak aortic jet velocity in the perioperative period-machine variability: implications for assessment of aortic stenosis severity.

Variation in echocardiography machines and probes are not well described in the perioperative period. We aimed to compare the estimation of severity of aortic stenosis with transthoracic echocardiography (TTE) using two semi-portable ultrasound machines. Experienced cardiac anaesthetists performed a limited transthoracic echocardiogram with two different semi-portable ultrasound machines in patients with known aortic stenosis. The peak aortic jet velocity with continuous-wave Doppler and the time taken to obtain an acceptable envelope were recorded. The Sonosite M Turbo often underestimated the peak jet velocities (median jet velocity [IQR] 2.25 m/s [1.95 to 3.4] versus 3.85 m/s (3 to 4.2); P <0.001) and required more time to get a satisfactory envelope than the GE Vivid I. There was no statistically or clinically significant difference between the velocities obtained from the Vivid I and those measured on the patient's formal cardiology preoperative transthoracic echocardiogram (median [IQR]: 3.95 m/s [3.0 to 4.7]; P=0.3). However, the velocities obtained by the M Turbo were significantly lower than those obtained by the formal preoperative transthoracic echocardiogram (P <0.001). With the expansion of transthoracic echocardiography amongst anaesthetists, underestimation of the peak aortic jet velocity can significantly underestimate the severity of aortic stenosis with potentially lethal clinical consequences. Semi-portable ultrasound machines with echocardiographic capability are not necessarily equivalent and can result in underestimation of severity of aortic stenosis.

Differential left ventricular outflow tract remodeling and dynamics in aortic stenosis.

Left ventricular outflow tract (LVOT) geometry is variable and often elliptical, which can affect aortic valve area calculation in patients with aortic stenosis (AS). Specific differences in LVOT geometry and dynamics between patients with AS and normal control subjects have not been described. The aim of this study was to test the hypothesis that differences in LVOT geometry in patients with AS might relate to variable LVOT remodeling and stiffness relative to normal control subjects. In 54 patients with severe AS and 33 control subjects without AS, LVOT geometry, dynamics, remodeling, and stiffness were assessed by three-dimensional transesophageal echocardiography. LVOT stiffness was measured by calculating the distensibility coefficient, defined as the percentage change in LVOT area relative to change in left ventricular pressure. LVOT remodeling was assessed by measuring the posterior LVOT wall thickness. Multivariate linear regression analysis was used to determine independent associations with peak systolic LVOT ellipticity. LVOT area by three-dimensional transesophageal echocardiographic planimetry was compared with areas obtained assuming circular or elliptical geometry. At end-diastole, LVOT geometry was similar between patients with AS and normal control subjects. In patients with AS, however, the percentage change in cross-sectional area (7.5% vs 14.7%, P<.001) from end-diastole to peak systole was lower compared with normal control subjects, while peak systolic ellipticity index was higher in patients with AS (1.18 vs 1.08, P<.001). Compared with control subjects, patients with AS had lower distensibility coefficients (4.7±1.9 × 10(4) vs 12.5±5.3×10(4) mm Hg(-1), P<.001) and higher posterior LVOT wall thickness (3.5±0.8 vs 2.3±0.5mm, P<.001). In multivariate analysis, posterior LVOT wall thickness and distensibility coefficient were independently associated with peak systolic LVOT ellipticity index. LVOT area underestimation by transthoracic echocardiography was higher in patients with AS when assuming circular geometry (20% vs 12%, P=.001). The LVOT is less distensible and undergoes remodeling in severe AS. These changes lead to greater peak systolic ellipticity and greater LVOT cross-sectional area underestimation relative to normal control subjects. These findings have important implications for the assessment of AS severity.

Relation of Dimensionless Index to Long-Term Outcome in Aortic Stenosis With Preserved LVEF

ObjectivesThe aim of this study was to assess the role of the dimensionless index (DI) in a registry of patients with aortic stenosis (AS) to objectively establish prognostic DI thresholds for various degrees of AS severity. BackgroundDI is a classic marker of severity in AS that does not rely on the estimation of the left ventricular outflow tract (LVOT) cross-sectional area. Although DI estimation is straightforward, its outcome implications have never been tested in the context of routine clinical practice. MethodsThis analysis includes 488 patients with preserved (≥50%) ejection fraction and no or minimal subjective symptoms, diagnosed with ≥ mild AS. DI was computed as the ratio of the LVOT time-velocity integral to that of the aortic valve jet, and on the basis of the correlation with peak aortic jet velocity, the population was divided into 3 groups: DI <0.20, DI 0.20 to 0.25, and DI >0.25. ResultsThe 5-year survival free of events (death or need for aortic valve replacement) was 56 ± 3% for DI >0.25, 41 ± 6% for DI 0.20 to 0.25, and 22 ± 5% for DI <0.20 (p for trend <0.001). The risk of events increased linearly with DI <0.25 (adjusted hazard ratio [HR]: 1.14; 95% confidence interval [CI]: 1.05 to 1.29) per 0.05 DI decrement; p = 0.015). On multivariable analysis, compared with patients with DI >0.25, those with DI 0.20 to 0.25 and those with DI <0.20 incurred an excess risk of events (adjusted HR: 1.65; 95% CI: 1.20 to 2.27 for DI 0.20 to 0.25 vs. DI >0.25, and adjusted HR: 2.62; 95% CI: 1.90 to 3.63 for DI <0.20 vs. DI >0.25). The association of DI and outcome was consistent in subgroups, with no interaction between DI outcome prediction and LVOT diameter, body surface area, or index stroke volume (all p for interaction ≥0.10) ConclusionsOur results demonstrate that the DI is a simple and reliable marker of AS severity with clear prognostic implications. DI <0.25 is associated with an excess risk of events after diagnosis; therefore, this cutoff should be used for AS severity assessment and for therapeutic decisions.

Non-invasive Assessment of the Severity of Aortic Stenosis by Doppler Derived Aortic Valve Coefficient: A Retrospective Feasibility Study in Humans

Background: Accurate assessment of the severity of stenosis is critical in patients with aortic stenosis. The ambiguities and imprecisions of the current diagnostic parameters can result in suboptimal clinical decisions. In this feasibility study, we investigate the functional diagnostic parameter AVC (Aortic Valve coefficient: ratio of the total transvalvular pressure drop to the proximal dynamic pressure) in the non-invasive assessment of the severity of aortic stenosis by correlating with the current diagnostic parameters. Original Research Article Paul et al.; BJMMR, 8(2): 177-191, 2015; Article no.BJMMR.2015.438 178 Methods and Results: AVC was calculated using Doppler measured diagnostic parameters obtained from retrospective chart reviews. A theoretical pressure recovery correction was applied to the pressure drop calculated from Doppler measurements to obtain AVC. A statistically significant and strong combined linear correlation (r = 0.93, p<0.001) of AVC with the transvalvular pressure drop and the left ventricular outflow tract velocity was observed. The mean values of AVC were shown to better delineate moderate and severe stenosis (54% difference) than the mean values of Doppler measured pressure drop and aortic valve area (22% and 25% difference, respectively), when the patients were categorized based on the catheterization measured pressure drop. Conclusion: The feasibility of using pressure and flow measurements obtained from Doppler measurements in a single combined diagnostic index for the assessment of aortic stenosis severity has been evaluated. The nondimensional clinical parameter, AVC, is expected to account for the variation in flow and pressure drop and thus improve the delineation of different grades of aortic stenosis. AVC must be further evaluated in a controlled prospective study.

Low-Flow Aortic Stenosis and Reduced Ejection Fraction: New Insights.

Low-Flow Aortic Stenosis and Reduced Ejection Fraction: New Insights.

Two dimensional speckle tracking echocardiography in detection of subclinical left ventricular systolic dysfunction in patients with severe aortic stenosis

IntroductionSubclinical left ventricular (LV) systolic dysfunction may develop in patients with severe aortic stenosis (AS) despite normal LV ejection fraction (EF%). The aim of the studyTo evaluate the role of two dimensional (2D) speckle tracking echocardiography (STE) in detection of subclinical LV systolic dysfunction in patients with severe AS. Patients and methodThe study included 50 patients with severe AS (mean age: 45 ± 9 years) and 30 age-matched healthy individuals (mean age 43 ± 7 years. Conventional echocardiographic parameters used for the assessment of AS severity were measures and 2D Speckle tracking imaging of the peak systolic strain curves of the Inferior septum and lateral wall in the apical four-chamber view (4C-PLS), the Inferior and anterior wall was in the apical two chamber view (2C-PLS), and the infero lateral and anterior septum in the apical three-chamber view (3C-PLS) were obtained. Left ventricular global longitudinal systolic strain (LV-GLS) was calculated by averaging the peak systolic values of the 6 LV walls. ResultsLV-GLS was significantly reduced in patients with AS compared to controls (<0.001) and negatively correlated with left ventricular mass index (LVMI) (r = −0.47, p = 0.01) irrespective of EF%, maximum velocity, peak pressure gradient and mean pressure gradient across the aortic valve and the aortic valve area. ConclusionPatients with severe AS have evidence of subclinical LV systolic dysfunction despite preserved EF%. 2D speckle tracking appears to be useful in detection of subclinical LV dysfunction in patients with AS.