Size-adjusted left ventricular outflow tract diameter reference values: a safeguard for the evaluation of the severity of aortic stenosis

Unmet needs and knowledge gaps in aortic stenosis: A position paper from the Heart Valve Council of the French Society of Cardiology

Nowadays, valvular heart disease remains a significant challenge among cardiovascular diseases, affecting millions of people worldwide and exerting substantial pressure on healthcare systems. Within the spectrum of valvular heart disease, aortic stenosis is the most common valvular lesion in developed countries. Despite notable advances in understanding its pathophysiological processes, improved cardiovascular imaging techniques and expanding therapeutic options in recent years, there are still unmet needs and knowledge gaps regarding aortic stenosis pathophysiology, severity assessment, management and decision-making strategy. This review, prepared on behalf of the Heart Valve Council of the French Society of Cardiology, describes these gaps and future research perspectives to improve the outcome of patients with aortic stenosis.

Cardiopulmonary haemodynamics in Tibetans and Han Chinese during rest and exercise

During sea-level exercise, blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) in humans without a patent foramen ovale (PFO) is negatively correlated with pulmonary pressure. Yet, it is unknown whether the superior exercise capacity of Tibetans well adapted to living at high altitude is the result of lower pulmonary pressure during exercise in hypoxia, and whether their cardiopulmonary characteristics are significantly different from lowland natives of comparable ancestry (e.g. Han Chinese). We found a 47% PFO prevalence in male Tibetans (n = 19) and Han Chinese (n = 19) participants. In participants without a PFO (n = 10 each group), we measured heart structure and function at rest and peak oxygen uptake (V ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ ), peak power output (W ̇ p e a k ${{\dot{W}}_{peak}}$ ), pulmonary artery systolic pressure (PASP), blood flow through IPAVA and cardiac output (Q ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ ) at rest and during recumbent cycle ergometer exercise at 760 Torr (SL) and at 410 Torr (ALT) barometric pressure in a pressure chamber. Tibetans achieved a higherW peak ${W}_{\textit{peak}}$ than Han, and a higherV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ at ALT without differences in heart rate, stroke volume orQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ . Blood flow through IPAVA was generally similar between groups. Increases in PASP and total pulmonary resistance at ALT were comparable between the groups. There were no differences in the slopes of PASP plotted as a function ofQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ during exercise. In those without PFO, our data indicate that the superior aerobic exercise capacity of Tibetans over Han Chinese is independent of cardiopulmonary features and more probably linked to differences in local muscular oxygen extraction. KEY POINTS: Patent foramen ovale (PFO) prevalence was 47% in Tibetans and Han Chinese living at 2 275 m. Subjects with PFO were excluded from exercise studies. Compared to Han Chinese, Tibetans had a higher peak workload with acute compression to sea level barometric pressure (SL) and acute decompression to 5000 m altitude (ALT). Comprehensive cardiac structure and function at rest were not significantly different between Han Chinese and Tibetans. Tibetans and Han had similar blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) during exercise at SL. Peak pulmonary artery systolic pressure (PASP) and total pulmonary resistance were different between SL and ALT, with significantly increased PASP for Han compared to Tibetans at ALT. No differences were observed between groups at acute SL and ALT.

Left ventricular outflow tract velocity-time integral improves outcome prediction in patients with secondary mitral regurgitation

AIMS

Left ventricular outflow velocity-time integral (LVOT-VTI) has been shown to improve outcome prediction in different patients' subsets, with or without heart failure (HF). Nevertheless, the prognostic value of LVOT-VTI in patients with HF and secondary mitral regurgitation (MR) has never been investigated so far. Therefore, in the present study, we aimed to assess the prognostic value different metrics of LV forward output, including LVOT-VTI, in HF patients with secondary MR.

METHODS AND RESULTS

Consecutive patients with HF and moderate-to-severe/severe secondary MR and systolic dysfunction (i.e., left ventricular ejection fraction [LVEF] <50%) were retrospectively selected and followed-up for the primary endpoint of cardiac death. Out of the 287 patients analyzed (aged 74 ± 11 years, 70% men, 46% ischemic etiology, mean LVEF 30 ± 9%, mean LVOT-VTI 20 ± 5 cm), 71 met the primary endpoint over a 33-month median follow-up (16-47 months). Patients with an LVOT-VTI ≤17 cm (n = 96, 32%) showed the greatest risk of cardiac death (Log Rank 44.3, p < 0.001) and all-cause mortality (Log rank 8.6, p = 0.003). At multivariable regression analysis, all the measures of LV forward volume (namely LVOT-VTI, stroke volume index, cardiac output, and cardiac index) were predictors of poor outcomes. Among these, LVOT-VTI was the most accurate in risk prediction (univariable C-statistics 0.70 [95%CI 0.64-0.77]).

CONCLUSION

Left ventricular forward output, noninvasively estimated through LVOT-VTI, improves outcome prediction in HF patients with low LVEF and secondary MR.

CARDIAC OUTPUT IN CRITICALLY ILL PATIENTS CAN BE ESTIMATED EASILY AND ACCURATELY USING THE MINUTE DISTANCE OBTAINED BY PULSED-WAVE DOPPLER

ABSTRACT

Background: Cardiac output (CO) assessment is essential for management of patients with circulatory failure. Among the different techniques used for their assessment, pulsed-wave Doppler cardiac output (PWD-CO) has proven to be an accurate and useful tool. Despite this, assessment of PWD-CO could have some technical difficulties, especially in the measurement of left ventricular outflow tract diameter (LVOTd). The use of a parameter such as minute distance (MD) which avoids LVOTd in the PWD-CO formula could be a simple and useful way to assess the CO in critically ill patients. Therefore, the aim of this study was to evaluate the correlation and agreement between PWD-CO and MD. Methods: A prospective and observational study was conducted over 2 years in a 30-bed intensive care unit (ICU). Adult patients who required CO monitoring were included. Clinical echocardiographic data were collected within the first 24 h and at least once more during the first week of ICU stay. PWD-CO was calculated using the average value of three LVOTd and left ventricular outflow tract velocity-time integral (LVOT-VTI) measurements, and heart rate. Minute distance was obtained from the product of LVOT-VTI × heart rate. Pulsed-wave Doppler cardiac output was correlated with MD using linear regression. Cardiac output was quantified from the MD using the equation defined by linear regression. Bland-Altman analysis was also used to evaluate the level of agreement between CO calculated from MD (MD-CO) and PWD-CO. The percentage error was calculated. Results: A total of 98 patients and 167 CO measurements were analyzed. Sixty-seven (68%) were male, the median age was 66 years (interquartile range [IQR], 53-75 years), and the median Acute Physiology and Chronic Health Evaluation II score was 22 (IQR, 16-26). The most common cause of admission was shock in 81 patients (82.7%). Sixty-nine patients (70.4%) were mechanically ventilated, and 68 (70%) required vasoactive drugs. The median CO was 5.5 L/min (IQR, 4.8-6.6 L/min), and the median MD was 1,850 cm/min (IQR, 1,520-2,160 cm/min). There was a significant correlation between PWD-CO and MD-CO in the general population ( R2 = 0.7; P < 0.05). This correlation improved when left ventricular ejection fraction (LVEF) was less than 60% ( R2 = 0.85, P < 0.05). Bland-Altman analysis showed good agreement between PWD-CO and MD-CO in the general population, the median bias was 0.02 L/min, the limits of agreement were -1.92 to +1.92 L/min. The agreement was better in patients with LVEF less than 60% with a median bias of 0.005 L/min and limits of agreement of -1.56 to 1.55 L/min. The percentage error was 17% in both cases. Conclusion: Measurement of MD in critically ill patients provides a simple and accurate estimate of CO, especially in patients with reduced or preserved LVEF. This would allow earlier cardiovascular assessment in patients with circulatory failure, which is of particular interest in difficult clinical or technical conditions.

Pitfalls and Tips in the Assessment of Aortic Stenosis by Transthoracic Echocardiography

Aortic stenosis (AS) is a valvular heart disease that significantly contributes to cardiovascular morbidity and mortality worldwide. The condition is characterized by calcification and thickening of the aortic valve leaflets, resulting in a narrowed orifice and increased pressure gradient across the valve. AS typically progresses from a subclinical phase known as aortic sclerosis, where valve calcification occurs without a transvalvular gradient, to a more advanced stage marked by a triad of symptoms: heart failure, syncope, and angina. Echocardiography plays a crucial role in the diagnosis and evaluation of AS, serving as the primary non-invasive imaging modality. However, to minimize misdiagnoses, it is crucial to adhere to a standardized protocol for acquiring echocardiographic images. This is because, despite continuous advances in echocardiographic technology, diagnostic errors still occur during the evaluation of AS, particularly in classifying its severity and hemodynamic characteristics. This review focuses on providing guidance for the imager during the echocardiographic assessment of AS. Firstly, the review will report on how the echo machine should be set to improve image quality and reduce noise and artifacts. Thereafter, the review will report specific emphasis on accurate measurements of left ventricular outflow tract diameter, aortic valve morphology and movement, as well as aortic and left ventricular outflow tract velocities. By considering these key factors, clinicians can ensure consistency and accuracy in the evaluation of AS using echocardiography.

A simplified echocardiographic formula to estimate cardiac index in the intensive care unit

BACKGROUND AND AIM

Measurement of cardiac index (CI) is crucial in the hemodynamic assessment of critically ill patients in the intensive care unit (ICU). The most reliable trans-thoracic echocardiography (TTE) technique for CI estimation is the left ventricular outflow tract (LVOT) Doppler method that requires, among other parameters, the LVOT cross-sectional area (CSA) measurement. However, inherent and practical disadvantages, mostly related to the ICU setting, hamper LVOT-CSA assessment. In this study, we aimed to validate a simplified formula, leveraging on LVOT-velocity time integral (VTI) and heart rate (HR) only, for non-invasive estimation of CI in ICU patients.

METHODS AND RESULTS

We prospectively enrolled 50 consecutive patients admitted to our ICU requiring pulmonary artery catheterization (PAC) over a one-year period. For each patient we measured the CI by PAC (CI_PAC) and TTE. The latter was obtained both with the "traditional formula" (traditional CI_TTE), requiring LVOT-CSA assessment, and our new "simplified formula" (simplified CI_TTE). The correlation between the simplified CI_TTE and CI_PAC was strong (r = 0.81) and resulted significantly greater than the traditional CI_TTE and CI_PAC correlation (r = 0.70; p < 0.05 for Pearson r coefficients comparison). Both TTE-based CI showed an acceptable agreement (+0.19 ± 0.48 L/min/m² for simplified CI_TTE and - 0.18 ± 0.58 L/min/m² for traditional CI_TTE) with the reference CI_PAC.

CONCLUSION

In this study, we validated a practical approach, leveraging on TTE LVOT-VTI and HR only, for non-invasive estimation of CI in ICU patients.

Grading of Aortic Stenosis: Is it More Complicated in Women?

Aortic stenosis (AS) is the most common valvular heart disease and the main indication for valvular replacement in older women. Correct AS grading is mandatory for an adequate selection of patients for both surgical and transcatheter aortic valve replacement. Women and men have different AS severity grades at the same level of aortic valve calcification. Moreover, besides having smaller cardiac volumes, left ventricular outflow tract and aortic size, women have a specific pattern of left ventricular structural and functional remodelling in response to the AS-related chronic pressure overload. Here, the sex-specific cardiac changes in AS that make AS grading more challenging in women, with consequences for the management and outcome of this group of patients, are reviewed.

A simple algorithm for differential diagnosis in hemodynamic shock based on left ventricle outflow tract velocity–time integral measurement: a case series

Echocardiography has gained wide acceptance among intensive care physicians during the last 15 years. The lack of accredited formation, the long learning curve required and the excessive structural orientation of the present algorithms to evaluate hemodynamically unstable patients hampers its daily use in the intensive care unit. The aim of this article is to show 4 cases where the use of our simple algorithm based on VTI, was crucial. Subsequently, to explain the benefit of using the proposed algorithm with a more functional perspective, as a means for clinical decision-making. A simple algorithm based on left ventricle outflow tract velocity–time integral measurement for a functional hemodynamic monitoring on patients suffering hemodynamic shock or instability is proposed by Spanish Critical Care Ultrasound Network Group. This algorithm considers perfusion and congestion variables. Its simplicity might be useful for guiding physicians in their daily decision-making managing critically ill patients in hemodynamic shock.

Calculated left ventricular outflow tract diameter for critically ill patients

A fast and reliable left ventricular outflow diameter (LVOTd) estimation may aid in quickly estimating cardiac output. However, obtaining a correct LVOTd can be difficult in intensive care patients, potentially leading to errors and a cardiac output deviation. In this study, the measured LVOTd was compared with the expected LVOTd when estimated using an existing formula in 1177 critically ill patients. We show that estimated LVOTd based on baseline data can aid when obtaining LVOTd is difficult or impossible and simplified estimation based on a formula may allow for more reliable and accessible measurement of cardiac output.

Size-adjusted aortic valve area: refining the definition of severe aortic stenosis

AIMS

Severe aortic valve stenosis (AS) is defined by an aortic valve area (AVA) <1 cm2 or an AVA indexed to body surface area (BSA) <0.6 cm/m2, despite little evidence supporting the latter approach and important intrinsic limitations of BSA indexation. We hypothesized that AVA indexed to height (H) might be more applicable to a wide range of populations and body morphologies and might provide a better predictive accuracy.

METHODS AND RESULTS

In 1298 patients with degenerative AS and preserved ejection fraction from three different countries and continents (derivation cohort), we aimed to establish an AVA/H threshold that would be equivalent to 1.0 cm2 for defining severe AS. In a distinct prospective validation cohort of 395 patients, we compared the predictive accuracy of AVA/BSA and AVA/H. Correlations between AVA and AVA/BSA or AVA/H were excellent (all R2 > 0.79) but greater with AVA/H. Regressions lines were markedly different in obese and non-obese patients with AVA/BSA (P < 0.0001) but almost identical with AVA/H (P = 0.16). AVA/BSA values that corresponded to an AVA of 1.0 cm2 were markedly different in obese and non-obese patients (0.48 and 0.59 cm2/m2) but not with AVA/H (0.61 cm2/m for both). Agreement for the diagnosis of severe AS (AVA < 1 cm2) was significantly higher with AVA/H than with AVA/BSA (P < 0.05). Similar results were observed across the three countries. An AVA/H cut-off value of 0.6 cm2/m [HR = 8.2(5.6-12.1)] provided the best predictive value for the occurrence of AS-related events [absolute AVA of 1 cm2: HR = 7.3(5.0-10.7); AVA/BSA of 0.6 cm2/m2 HR = 6.7(4.4-10.0)].

CONCLUSION

In a large multinational/multiracial cohort, AVA/H was better correlated with AVA than AVA/BSA and a cut-off value of 0.6 cm2/m provided a better diagnostic and prognostic value than 0.6 cm2/m2. Our results suggest that severe AS should be defined as an AVA < 1 cm2 or an AVA/H < 0.6 cm2/m rather than a BSA-indexed value of 0.6 cm2/m2.

Diagnosis and Management of Aortic Valve Stenosis: The Role of Non-Invasive Imaging

Aortic stenosis is the most common heart valve disease necessitating surgical or percutaneous intervention. Imaging has a central role for the initial diagnostic work-up, the follow-up and the selection of the optimal timing and type of intervention. Referral for aortic valve replacement is currently driven by the severity and by the presence of aortic stenosis-related symptoms or signs of left ventricular systolic dysfunction. This review aims to provide an update of the imaging techniques and seeks to highlight a practical approach to help clinical decision making.

Doppler Velocity Index Outcomes Following Surgical or Transcatheter Aortic Valve Replacement in the PARTNER Trials

OBJECTIVES

The aim of this study was to assess the association between Doppler velocity index (DVI) and 2-year outcomes for balloon-expandable SAPIEN 3 transcatheter aortic valve replacement (TAVR) and for surgical aortic valve replacement (SAVR).

BACKGROUND

DVI >0.35 is normal for a prosthetic valve, but recent studies suggest that DVI <0.50 is associated with poor outcomes following TAVR.

METHODS

Patients with severe aortic stenosis enrolled in the PARTNER (Placement of Aortic Transcatheter Valve) 2 (intermediate surgical risk) or PARTNER 3 (low surgical risk) trial undergoing TAVR (n = 1,450) or SAVR (n = 1,303) were included. Patients were divided into 3 DVI groups on the basis of core laboratory-assessed discharge or 30-day echocardiograms: DVI_LOW (≤0.35), DVI_INTERMEDIATE (>0.35 to ≤0.50), and DVI_HIGH (>0.50). Two-year outcomes were assessed.

RESULTS

Following TAVR, there were no differences among the 3 DVI groups in composite outcomes of death, stroke, or rehospitalization or in any individual components of 2-year outcomes (P > 0.70 for all). Following SAVR, there was no difference among DVI groups in the composite outcome (P = 0.27), but there was a significant association with rehospitalization (P = 0.02). Restricted cubic-spline analysis for combined outcomes showed an increased risk with post-SAVR DVI ≤0.35 but no relationship post-TAVR. DVI ≤0.35 was associated with increased 2-year composite outcome for SAVR (HR: 1.81; 95% CI: 1.29-2.54; P < 0.001), with no adverse outcomes for TAVR (P = 0.86).

CONCLUSIONS

In intermediate- and low-risk cohorts of the PARTNER trials, DVI ≤0.35 predicted worse 2-year outcomes following SAVR, driven primarily by rehospitalization, with no adverse outcomes associated with DVI following TAVR with the balloon-expandable SAPIEN 3 valve.

Indirect ultrasound evaluation of left ventricular outflow tract diameter implications for heart failure and aortic stenosis severity assessment

BACKGROUND

Whereas dependency of left ventricular outflow tract diameter (LVOTD) from body surface area (BSA) has been established and a BSA-based LVOTD formula has been derived, the relationship between LVOTD and aortic root and LV dimensions has never been explored. This may have implications for evaluation of LV output in heart failure (HF) and aortic stenosis (AS) severity.

METHODS

A cohort of 540 HF patients who underwent transthoracic echocardiography was divided in a derivation and validation subgroup. In the derivation subgroup (N = 340), independent determinants of LVOTD were analyzed to derive a regression equation, which was used for predicting LVOTD in the validation subgroup (N = 200) and compared with the BSA-derived formula.

RESULTS

LVOTD determinants in the derivation subgroup were sinuses of Valsalva diameter (SVD, beta = 0.392, P < .001), BSA (beta = 0.229, P < .001), LV end-diastolic diameter (LVEDD, beta = 0.145, P = .001), and height (beta = 0.125, P = .037). The regression equation for predicting LVOTD with the aforementioned variables (LVOTD = 6.209 + [0.201 × SVD] + [1.802 × BSA] + [0.03 × LVEDD] + [0.025 × Height]) did not differ from (P = .937) and was highly correlated with measured LVOTD (R = 0.739, P < .001) in the validation group. Repeated analysis with LV end-diastolic volume instead of LVEDD and/or accounting for gender showed similar results, whereas BSA-derived LVOTD values were different from measured LVOTD (P < .001).

CONCLUSION

Aortic root and LV dimensions affect LVOTD independently from anthropometric data and are included in a new comprehensive equation for predicting LVOTD. This should improve evaluation of LV output in HF and severity of AS when direct LVOTD measurement is difficult or impossible.

Left ventricular output indices in hospitalized heart failure: when "simpler" may not mean "better"

Assessment of left ventricular (LV) output in hospitalized patients with heart failure (HF) is important to determine prognosis. Although echocardiographic LV ejection fraction (EF) is generally used to this purpose, its prognostic value is limited. In this investigation LV-EF was compared with other echocardiographic per-beat measures of LV output, including non-indexed stroke volume (SV), SV index (SVI), stroke distance (SD), ejection time (ET), and flow rate (FR), to determine the best predictor of all-cause mortality in patients hospitalized with HF. A final cohort of 350 consecutive patients hospitalized with HF who underwent echocardiography during hospitalization was studied. At a median follow-up of 2.7 years, 163 patients died. Non-survivors at follow-up had lower SD, SVI and SV, but not ET, FR and LV-EF than survivors. At multivariate analysis, only age, systolic blood pressure, chronic kidney disease, chronic obstructive pulmonary disease, use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and SVI remained significantly associated with outcome [HR for SVI 1.13 (1.04-1.22), P = 0.003]. In particular, for each 5 ml/m² decrease in SVI, a 13% increase in risk of mortality for any cause was observed. SVI is a powerful prognosticator in HF patients, better than other per-beat measures, which may be simpler but partial or incomplete descriptors of LV output. SVI, therefore, should be considered for the routine echocardiographic evaluation of patients hospitalized with HF to predict prognosis.

Moderate Aortic Stenosis and Heart Failure With Reduced Ejection Fraction: Can Imaging Guide Us to Therapy?

Clinical management of patients with only moderate aortic stenosis (AS) but symptoms of heart failure with a reduced left ventricular ejection fraction (HFrEF) is challenging. Current guidelines recommend clinical surveillance with multimodality imaging; aortic valve replacement (AVR) is deferred until the stenosis becomes severe. Given the known benefits of afterload reduction in management of patients with HFrEF, it has been hypothesized that AVR may be beneficial in patients with only moderate AS who present with HFrEF. In this article, we first review the current approach for management of patients with moderate AS and HFrEF based on close clinical and imaging surveillance with AVR delayed until AS is severe. We then discuss the case for transcatheter AVR (TAVR) earlier in the disease course, when AS is moderate, based on stress echocardiographic data. We conclude with a detailed summary of the TAVR UNLOAD (Transcatheter Aortic Valve Replacement to UNload the Left Ventricle in Patients With ADvanced Heart Failure) trial, in which patients with moderate AS and HFrEF are randomized to guideline-directed heart failure therapy alone versus guideline-directed heart failure therapy plus TAVR.

Expert consensus document on the assessment of the severity of aortic valve stenosis by echocardiography to provide diagnostic conclusiveness by standardized verifiable documentation

According to recent recommendations on echocardiographic assessment of aortic valve stenosis direct measurement of transvalvular peak jet velocity, calculation of transvalvular mean gradient from the velocities using the Bernoulli equation and calculation of the effective aortic valve area by continuity equation are the appropriate primary key instruments for grading severity of aortic valve stenosis. It is obvious that no gold standard can be declared for grading the severity of aortic stenosis. Thus, conclusions of the exclusive evaluation of aortic stenosis by Doppler echocardiography seem to be questionable due to the susceptibility to errors caused by methodological limitations, mathematical simplifications and inappropriate documentation. The present paper will address practical issues of echocardiographic documentation to satisfy the needs to analyze different scenarios of aortic stenosis due to various flow conditions and pressure gradients. Transesophageal and multidimensional echocardiography should be implemented for reliable measurement of geometric aortic valve area and of cardiac dimensions at an early stage of the diagnostic procedure to avoid misinterpretation due to inconsistent results.

Contemporary Imaging of Aortic Stenosis

Degenerative or fibrocalcific aortic stenosis (AS) is now the most common native valvular heart disease assessed and managed by cardiologists in developed countries. Transthoracic echocardiography remains the quintessential imaging modality for the non-invasive characterisation of AS due to its widespread availability, superior assessment of flow haemodynamics, and a wealth of prognostic data accumulated over decades of clinical utility and research applications. With expanding technologies and increasing availability of treatment options such as transcatheter aortic valve replacements, in addition to conventional surgical approaches, accurate and precise assessment of AS severity is critical to guide decisions for and timing of interventions. Despite clear guideline echocardiographic parameters demarcating severe AS, discrepancies between transvalvular velocities, gradients, and calculated valve areas are commonly encountered in clinical practice. This often results in diagnostically challenging cases with significant implications. Greater emphasis must be placed on the quality of performance of basic two dimensional (2D) and Doppler measurements (attention to detail ensuring accuracy and precision), incorporating ancillary haemodynamic surrogates, understanding study- or patient-specific confounders, and recognising the role and limitations of stress echocardiography in the subgroups of low-flow low-gradient AS. A multiparametric approach, along with the incorporation of multimodality imaging (cardiac computed tomography or magnetic resonance imaging) in certain scenarios, is now mandatory to avoid incorrect misclassification of severe AS. This is essential to ensure appropriate selection of patients who would most benefit from interventions on the aortic valve to relieve the afterload mismatch resulting from truly severe valvular stenosis.

Reference intervals and percentile curve for left ventricular outflow tract (LVOT), velocity time integral (VTI), and LVOT-VTI-derived hemodynamic parameters in healthy children and adolescents: Analysis of echocardiographic methods association and agreement

BACKGROUND

Echocardiographic reference intervals (RIs) for left ventricular outflow tract (LVOT) and velocity time integral (VTI) are scarce in pediatrics.

AIMS

(a) to generate RIs and percentiles for LVOT, VTI, and hemodynamic variables in healthy children and adolescents from Argentina; (b) to analyze the equivalence between stroke volume (SV), cardiac output (CO), and cardiac index (CI) obtained from two-dimensional echocardiography (2D) and LVOT-VTI analysis with pulsed wave Doppler (PWD); and (c) to analyze the association between subjects' characteristics and VTI and LVOT-VTI-derived parameters.

METHODS

Two-dimensional and PWD studies were done in 385 subjects (5-24 years). Mean and standard deviation age-related and body surface area (BSA)-related equations were obtained for VTI and LVOT-VTI-derived parameters (parametric regression methods based on fractional polynomials). BSA- and age-specific percentiles were determined.

RESULTS

Pulsed wave Doppler- and 2D-derived parameters were positively correlated. However, PWD values were always lower than those from 2D. Specific RIs for PWD and 2D data were necessary. Covariance analysis showed that sex-specific RIs were required for LVOT, but not for VTI, VTI-derived CO and CI. Age-related RIs were obtained for LVOT, LVOT-VTI, and VTI-derived CO and CI. BSA-related RIs for VTI-derived CO and CI were obtained.

CONCLUSIONS

Stroke volume, CO, and CI data from 2D and PWD are not equivalent. An accurate analysis of LVOT-VTI-derived parameters requires considering age and BSA. In this study, age- and BSA-related RIs and percentiles for LVOT, VTI, and hemodynamic parameters in healthy children and adolescents were determined, discriminating data according to the methodological approach (2D or PWD).

Optimizing Management of Heart Failure by Using Echo and Natriuretic Peptides in the Outpatient Unit

Chronic heart failure (HF) is an important public health problem and is associated with high morbidity, high mortality, and considerable healthcare costs. More than 90% of hospitalizations due to worsening HF result from elevations of left ventricular (LV) filling pressures and fluid overload, which are often accompanied by the increased synthesis and secretion of natriuretic peptides (NPs). Furthermore, persistently abnormal LV filling pressures and a rise in NP circulating levels are well known indicators of poor prognosis. Frequent office visits with the resulting evaluation and management are most often needed. The growing pressure from hospital readmissions in HF patients is shifting the focus of interest from traditionally symptom-guided care to a more specific patient-centered follow-up care based on clinical findings, BNP and echo. Recent studies supported the value of serial NP measurements and Doppler echocardiographic biomarkers of elevated LV filling pressures as tools to scrutinize patients with impending clinically overt HF. Therefore, combination of echo and pulsed-wave blood-flow and tissue Doppler with NPs appears valuable in guiding ambulatory HF management, since they are potentially useful to distinguish stable patients from those at high risk of decompensation.

Assessment of aortic valve disease - a clinician oriented review

Aortic valve disease [aortic stenosis (AS) and aortic regurgitation (AR)] represents an important global health problem; when severe, aortic valve disease carries poor prognosis. For AS, aortic valve replacement, either surgical or interventional, may provide definite treatment in carefully selected patients. For AR, valve surgery (either replacement or - in selected cases - aortic valve repair) remains the gold standard of care. To properly identify those patients who are candidates for surgery, the clinician has to carefully assess the severity of valve disease with an understanding of the potential pitfalls involved in these assessments. This review focuses on the practical issues concerning the evaluation of patients with AS and AR from a general cardiologist’s perspective. The most important issues regarding the documentation of the severity of AS and AR are summarized. More specific issues, such as the role of stress echocardiography, other imaging techniques and details regarding the treatment options (medical, surgical, or interventional), are mentioned briefly.

Accuracy of Echocardiographic Cardiac Index Assessment in Subjects with Preserved Left Ventricular Ejection Fraction

INTRODUCTION

We aimed to determine the accuracy of the echocardiographic assessment of cardiac index (CI) in subjects with preserved left ventricular ejection fraction (LVEF).

METHODS

Thirty-three subjects with LVEF >50%, normal sinus rhythm, and a broad spectrum of hemodynamic profiles underwent echocardiography immediately followed by right heart catheterization. As gold standards, CI was assessed using thermodilution [CI (TD)] and the Fick method [CI (F)]. Echocardiographic CI was assessed by four methods: from the left ventricular outflow tract (LVOT) velocity time integral and the LVOT diameter as measured [CI (LVOTm)] as well as estimated from body surface area [CI (LVOTe)], and from stroke volume indices assessed using the biplane [CI (BP)] and monoplane [CI (MP)] methods.

RESULTS

The mean CI (TD), CI (F), CI (LVOTm), CI (LVOTe), CI (BP), and CI (MP) were 3.0 ± 0.9, 3.1 ± 0.7, 2.8 ± 0.6, 3.3 ± 0.6, 2.0 ± 0.6, and 2.2 ± 0.7 L/min/m(2) . There were modest correlations between CI (TD) and CI (F) and all four noninvasive measures of CI with r(2) values ranging from 0.09 to 0.30. CI (LVOTm) underestimated CI (TD) and CI (F) by 0.3 and 0.3 L/min/m(2) , CI (LVOTe) overestimated CI (TD) and CI (F) by 0.3 and 0.2 L/min/m(2) , and CI (BP) and CI (MP) underestimated CI (TD) and CI (F) by 1.1 and 1.1 L/min/m(2) and 0.9 and 0.9 L/min/m(2) , respectively, with large limits of agreement for all comparisons.

CONCLUSIONS

In subjects with nondilated left ventricles with preserved LVEF, flow- or volume-based measures of CI by 2D echocardiography may not accurately reflect CI (TD) and CI (F). Further larger studies are required to verify our findings and to evaluate the accuracy of contrast and 3D echocardiography in this setting.

Comparison between cardiovascular magnetic resonance and transthoracic Doppler echocardiography for the estimation of effective orifice area in aortic stenosis

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 cm2) and seven (7) 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 (ALVOT, 3.84 ± 0.80 cm2) compared to CMR (4.78 ± 1.05 cm2). On the other hand, TTE overestimated the LVOT velocity-time integral (VTILVOT: 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 TTE-derived and CMR-derived EOAs (1.53 ± 0.67 vs. 1.59 ± 0.73 cm2, r = 0.92, bias = 0.06 ± 0.29 cm2). 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.

CONCLUSION

Underestimation of ALVOT by TTE is compensated by overestimation of VTILVOT, thereby resulting in a good concordance between TTE and CMR for estimation of aortic valve EOA. CMR was associated with less intra- and inter- observer measurement variability compared to TTE. CMR provides a non-invasive and reliable alternative to Doppler-echocardiography for the quantification of AS severity.