Direct measurement of left ventricular outflow tract by transthoracic real-time 3D-echocardiography increases accuracy in assessment of aortic valve stenosis

Use of two- and three-dimensional echocardiography for assessment of the left ventricular outflow tract and aortic orifice areas in dogs

INTRODUCTION/OBJECTIVES

In clinical practice, dogs are screened for subaortic stenosis (SAS) using two-dimensional (2DE) and Doppler echocardiography. There is no accepted antemortem diagnostic criterion to distinguish between mild SAS and unaffected, therefore additional means of evaluating the left ventricular outflow tract (LVOT) and aorta may be desirable. This study sought to determine and compare LVOT and aortic orifice areas using 2DE and three-dimensional echocardiography (3DE) in apparently healthy dogs of various breeds and somatotypes.

ANIMALS, MATERIALS, AND METHODS

Sixty-nine healthy, privately-owned dogs. The LVOT and aortic orifice areas were determined using 2DE aortic valve (AV) diameter-derived area; the continuity equation (CE); and 3DE planimetry of the LVOT, AV, sinus of Valsalva, and sinotubular junction. Orifice areas were indexed to body surface area (BSA).

RESULTS

Obtaining 3DE images and performing planimetry were feasible in all dogs. The mean indexed area measured using the 2DE AV diameter (2.85 cm2/m2) was significantly lower than that derived from 3DE AV planimetry (3.85 cm2/m2; mean difference, 1.00 cm2/m2; P<0.001). There was poor agreement between the effective area calculated using the CE and the anatomic areas calculated using 2DE AV diameter and 3DE planimetry. The area calculated using the CE was less than all other calculations of area. Interobserver and intraobserver repeatability and reproducibility for 3DE planimetry were excellent.

CONCLUSIONS

Methods for determining aortic orifice areas in dogs are not interchangeable, and this must be taken into account if these methods are investigated in the evaluation of dogs with SAS in the future.

Calculation of Aortic VAlve and LVOT Areas by a Modified Continuity Equation Using Different Echocardiography Methods: The CAVALIER Study

Background: The area of the left ventricular outflow tract (A_LVOT) represents a major component of the continuity equation (CE), which is, i.a., crucial to calculate the aortic valve (AV) area (A_AV). The A_LVOT is typically calculated using 2D echo assessments as the measured anterior–posterior (a/p) extension, assuming a round LVOT base. Anatomically, however, usually an elliptical shape of the LVOT base is present, with the long diameter extending from the medial–lateral axis (m/l), which is not recognized by two-dimensional (2D) echocardiography. Objective: We aimed to compare standard and three-dimensional (3D)-echocardiography-derived A_LVOT calculation and its use in a standard CE (CE_std) and a modified CE (CE_mod) to calculate the A_AV vs. computed tomography (CT) multi-planar reconstruction (MPR) measurements of the anatomical A_LVOT, and A_AV, respectively. Methods: Patients were selected if 3D transthoracic echocardiography (TTE), 3D transesophageal echocardiography (TEE), and cardiac CT were all performed, and imaging quality was adequate. The A_LVOT was assessed using 2D calculation, (a/p only), 3D-volume MPR, and 3D-biplane calculation (a/p and m/l). A_AV was measured using both CE_std and CE_mod, and 3D-volume MPR. Data were compared to corresponding CT analyses. Results: From 2017 to 2018, 107 consecutive patients with complete and adequate imaging data were included. The calculated A_LVOT was smaller when assessed by 2D- compared to both 3D-volume MPR and 3D-biplane calculation. Calculated A_AV was correspondingly smaller in CE_std compared to CE_mod or 3D-volume MPR. The A_LVOT and A_AV, using data from 3D echocardiography, highly correlated and were congruent with corresponding measurements in CT. Conclusion: Due to the elliptic shape of the LVOT, use of measurements and calculations based on 2D echocardiography systematically underestimates the A_LVOT and dependent areas, such as the A_AV. Anatomically correct assessment can be achieved using 3D echocardiography and adapted calculations, such as CE_mod.

Diagnostic Work-Up of the Aortic Patient: An Integrated Approach toward the Best Therapeutic Option

Aortic stenosis (AS) is the most common valvular heart disease. In the last decade, transcatheter aortic valve implantation (TAVI) has become the standard of care for symptomatic patients at high surgical risk. Recently, indications to TAVI have also been extended to the low surgical risk and intermediate surgical risk populations. Consequently, in this setting, some aspects acquire greater relevance: surgical risk evaluation, clinical assessment, multimodality imaging of the valve, and management of coronary artery disease. Moreover, future issues such as coronary artery re-access and valve-in-valve interventions should be considered in the valve selection process. This review aims to summarize the principal aspects of a multidimensional (multidisciplinary) and comprehensive preprocedural work-up. The Heart Team is at the center of the decision-making process of the management of aortic valve disease and bears responsibility for offering each patient a tailored approach based on an individual evaluation of technical aspects together with the risks and benefits of each modality. Considering the progressive expansion in TAVI indication and technological progress, the role of a work-up and multidisciplinary Heart Team will be even more relevant.

3D Echocardiography for Rheumatic Heart Disease Analysis: Ready for Prime Time

Rheumatic heart disease (RHD) remains to be a very important health issue worldwide, mainly in underdeveloped countries. It continues to be a leading cause of morbidity and mortality throughout developing countries. RHD is a delayed non-suppurative immunologically mediated inflammatory response to the throat infection caused by a hemolytic streptococcus from the A group (Streptococcus pyogenes). RHD keeps position 1 as the most common cardiovascular disease in young people aged <25 years considering all the continents. The disease can lead to valvular cardiac lesions as well as to carditis. Rheumatic fever valvular injuries lead most commonly to the fusion and thickening of the edges of the cusps and to the fusion, thickening, and shortening of the chordae and ultimately to calcification of the valves. Valvular commissures can also be deeply compromised, leading to severe stenosis. Atrial and ventricular remodeling is also common following rheumatic infection. Mixed valvular lesions are more common than isolated valvular disorders. Echocardiography is the most relevant imaging technique not only to provide diagnostic information but also to enable prognostic data. Further, it presents a very important role for the correction of complications after surgical repair of rheumatic heart valvulopathies. Three-dimensional (3D) echocardiography provides additional anatomical and morphofunctional information of utmost importance for patients presenting rheumatic valvopathies. Accordingly, three-dimensional echocardiography is ready for routine use in patients with RHD presenting with valvular abnormalities.

Evaluation of mechanical prosthetic valves: the role of three dimensional echocardiography in calculating effective orifice area in obese vs non-obese individuals

Calculation of effective orifice area (EOA) is crucial for the evaluation of prosthetic valve (PV) function and there is lack of data on the best method, particularly in obese patients, in whom two-dimensional (2D) transthoracic echocardiography (TTE) is cumbersome. We sought to compare two methods of calculating EOA through Continuity equation; one using standard 2D-TTE and other three-dimensional (3D) stoke volume (SV), in patients with bileaflet mechanical PV stratified by body mass index (BMI). On conventional TTE, SV mas measured using standard 2D derived data and 3D derived SV in 38 aortic and 62 mitral PV patients who were referred for further evaluation for mild/moderate symptoms of dyspnea. Patients were categorized with regard to transprosthetic flow into 'normal-flow' and 'high-flow' groups and several echocardiographic data including 2D and 3D EOA were compared. Rates of obesity (BMI ≥ 30) were similar within high and normal flow groups of mitral and aortic PV patients. Correlation and agreement of 2D and 3D EOA was sought in patients with and without obesity. After identifying patients with possible severe obstruction, ROC analysis was carried out to identify whether 2D and 3D derived EOA could discriminate those with obstruction. There was good correlation and agreement between two methods in patients without obesity in both mitral and aortic PV. In obese individuals, however, there was no correlation between 2D and 3D EOA; in whom echocardiographic criteria showing severe obstruction revealed that 3D EOA measurements were more accurate. ROC analysis supported that 3D EOA performs better to identify patients with obstructive characteristics. In patients with bileaflet PV, measurement of EAO by 3D derived SV yields more accurate results irrespective of BMI.

Two- or 3-Dimensional Echocardiography-Derived Cardiac Output Cannot Replace the Pulmonary Artery Catheter in Cardiac Surgery

OBJECTIVES

Three-dimensional (3D) transesophageal echocardiography (TEE) has been shown to be more accurate than 2D TEE for the evaluation of the left ventricular outflow tract area. The aim of the present study was to compare the agreement of 3D echocardiography-derived cardiac output (CO) with thermodilution-derived CO (TDCO) before and after cardiopulmonary bypass (CPB).

DESIGN

This was a prospective observational study of patients who underwent cardiac surgery between 2016 and 2018.

SETTING

Weill Cornell Medicine, a single large academic medical center.

PARTICIPANTS

The study comprised 78 patients undergoing elective cardiac surgery.

INTERVENTIONS

CPB, TEE, pulmonary artery catheter, and elective cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Two-dimensional CO, 3D CO-diameter, and 3D CO-area values pre-CPB were strongly correlated with one another both pre-CPB and post-CPB. The 3D CO-diameter and the 3D CO-area were mildly correlated, with TDCO measurements pre-CPB (r = 0.46 and 0.39, respectively) and post-CBP (r = 0.43 and 0.47, respectively). Pre-CPB 3D CO-diameter had the most agreement with TDCO in terms of bias (-0.13 L/min); however, the limits of agreement (LOA) were wide (-2.2- to- 2.45 L/min). Post-CPB, 3D CO-diameter had the most agreement with TDCO in terms of bias (0.41) but with wide LOA (-3.29 to 2.47). All pre-CPB echocardiography-derived CO (2D CO, 3D CO-diameter, 3D CO-area) had more agreement with TDCO than did post-CPB measurements.

CONCLUSIONS

Three-dimensional CO measurements were only modestly correlated with pulmonary artery catheter-derived CO pre-bypass and post-bypass. Despite low bias, the wide LOA from 2D CO, 3D CO-diameter, and 3D-area compared with TDCO suggested that the 2 methods are not interchangeable.

Direct Planimetry of Left Ventricular Outflow Tract Area by Simultaneous Biplane Imaging: Challenging the Need for a Circular Assumption of the Left Ventricular Outflow Tract in the Assessment of Aortic Stenosis

BACKGROUND

Evaluation of aortic stenosis (AS) requires calculation of aortic valve area (AVA), which relies on the assumption of a circular-shaped left ventricular outflow tract (LVOT). However, the LVOT is often elliptical, and the circular assumption underestimates the true LVOT area (LVOTA). Biplane imaging using transthoracic echocardiography allows direct planimetry of LVOTA. The aim of this study was to assess the feasibility of obtaining LVOTA using this technique and its impact on the discordance between AVA and gradient criteria in AS grading.

METHODS

We prospectively studied 134 patients (median age, 80 years; interquartile range, 73-87 years; 39% women) with AS, including 82 (61%) with severe AS and 52 (39%) with mild or moderate AS. LVOTA was traced using direct planimetry (LVOTA_biplane) and compared with LVOTA calculated using the circular assumption (LVOTA_circ). In a subset of patients who underwent cardiac computed tomography, direct planimetry of LVOTA was used as a reference standard.

RESULTS

LVOTA_biplane was significantly larger than LVOTA_circ (4.20 cm² [interquartile range, 3.66-4.90 cm²] vs 3.73 cm² [interquartile range, 3.14-4.15 cm²], P < .001). Among 30 patients who underwent cardiac computed tomography, LVOTA_biplane had better agreement with LVOTA by direct planimetry than LVOTA_circ (mean bias, -0.45 ± 0.63 vs -1.02 ± 0.63 cm²; P < .0001). Of 82 patients with severe AS (AVA ≤ 1 cm² using LVOTA_circ), 40 (49%) had discordant mean gradient (<40 mm Hg). By using LVOTA_biplane, patients with discordant AVA and mean gradient decreased from 49% to 27% (P = .004), and 29% of patients with severe AS were reclassified with moderate AS, with the highest percentage of reclassification in the group with low-gradient AS with preserved left ventricular ejection fraction.

CONCLUSIONS

Direct planimetry using biplane imaging avoids the inherent underestimation of LVOTA using the circular assumption. LVOTA obtained by biplane planimetry can lead to better concordance between AVA and mean gradient and classification of AS severity.

Feasibility and accuracy of real-time three-dimensional echocardiography in evaluating the aortic valve in children

Background

Aortic valve assessment by 2D transthoracic echocardiography is a relatively complex task owing to the unique anatomical features of the left ventricular outflow tract and its dynamic nature. We aimed to evaluate the accuracy of 3D transthoracic echocardiography [3D TTE] in assessing the aortic valve in children.

Results

The first group included 11 males and six females, with a mean age of 5.76 ± 6.39 years. All of these patients had aortic valve disease with a bicuspid variant. The second group included seven males and seven females, with a mean age of 4.4 ± 4.05 years. All of these patients had normal aortic valve morphology and had another congenital cardiac anomaly. The aortic valve annulus was assessed using the three modalities; 2D, 3D echocardiography in the vertical and horizontal diameters, and angiography. The aortic valve area was measured by 2D and 3D echocardiography using multiplane reformatted mode. The results of the analysis were then compared. They revealed that 3D echocardiographic measurement of the aortic annulus (horizontal diameter) correlated better with angiography than 2D and 3D (vertical diameter) echocardiographic measurements. There was a significant difference between the aortic valve area measured by 2D echocardiography and that measured by 3D echocardiography among the two groups, 2D echocardiography seems to underestimate the true aortic valve area.

Conclusion

The study concluded that 3D TTE with multiplane reformatted mode allows a more accurate assessment of the aortic valve when compared to 2D echocardiography and this correlates better with the angiographic findings.

Reliability of three-dimensional color flow Doppler and two-dimensional pulse wave Doppler transthoracic echocardiography for estimating cardiac output after cardiac surgery

BACKGROUND

Three-dimensional color flow Doppler (3DCF) is a new convenient technique for cardiac output (CO) measurement. However, to date, no one has evaluated the accuracy of 3DCF echocardiography for CO measurement after cardiac surgery. Therefore, this single-center, prospective study was designed to evaluate the reliability of three-dimensional color flow and two-dimensional pulse wave Doppler (2D-PWD) transthoracic echocardiography for estimating cardiac output after cardiac surgery.

METHODS

Post-cardiac surgical patients with a good acoustic window and a low dose or no dose of vasoactive drugs (norepinephrine < 0.05 μg/kg/min) were enrolled for CO estimation. Three different methods (third generation FloTrac/Vigileo™ [FT/V] system as the reference method, 3DCF, and 2D-PWD) were used to estimate CO before and after interventions (baseline, after volume expansion, and after a dobutamine test).

RESULTS

A total of 20 patients were enrolled in this study, and 59 pairs of CO measurements were collected (one pair was not included because of increasing drainage after the dobutamine test). Pearson's coefficients were 0.260 between the CO-FT/V and CO-PWD measurements and 0.729 between the CO-FT/V and CO-3DCF measurements. Bland-Altman analysis showed the bias between the absolute values of CO-FT/V and CO-PWD measurements was - 0.6 L/min with limits of agreement between - 3.3 L/min and 2.2 L/min, with a percentage error (PE) of 61.3%. The bias between CO-FT/V and CO-3DCF was - 0.14 L/min with limits of agreement between - 1.42 L /min and 1.14 L/min, with a PE of 29.9%. Four-quadrant plot analysis showed the concordance rate between ΔCO-PWD and ΔCO-3FT/V was 93.3%.

CONCLUSIONS

In a comparison with the FT/V system, 3DCF transthoracic echocardiography could accurately estimate CO in post-cardiac surgical patients, and the two methods could be considered interchangeable. Although 2D-PWD echocardiography was not as accurate as the 3D technique, its ability to track directional changes was reliable.

Valve area and the risk of overestimating aortic stenosis

OBJECTIVE

To obtain reference values of aortic valve area (AVA) in a large population and to infer the risk of overestimating aortic stenosis (AS) when focusing on flow-corrected indices of severity.

METHODS

We prospectively measured indices of AS in all consecutive echocardiograms performed in a large referral cardiac imaging laboratory for 1 year. We specifically analysed the distribution of AVA, indexed AVA and velocity ratio (Vratio) in patients with and without AS, the latter defined as the coexistence of valvular outflow obstruction (Vmax ≥2.5 m/s) and morphological findings of valve degeneration.

RESULTS

16 156 echocardiograms were analysed, 14 669 of which did not show valvular obstruction (peak jet velocity <2.5 m/s). In the latter group, AVA was 2.6±0.7 cm² in 8190 studies with normal valves and 2.3±0.7 cm² in 6479 studies with aortic sclerosis (AScl). There was a relatively wide overlap between values of AVA, indexed AVA and velocity ratio between studies of patients with AScl and AS. Values of AVA ≤1.0 cm² were found in 0.5% of studies with normal valves and 1.8% of studies with AScl. These proportions were 3.1% and 9.3% for AVA ≤1.5 cm², respectively. Vratio ≤0.25 were found in 0.1% of patients without obstruction. Risk factors for a small AVA in patients without obstruction were AScl, female sex, small body surface area, low ejection fraction and mitral regurgitation.

CONCLUSIONS

Normal values of continuity-equation derived AVA are smaller than previously considered. AVA values below cutoffs of moderate or severe AS can be found in patients without the disease. Flow-corrected indices may overestimate AS in patients with low gradients, particularly in the presence of well-identified risk factors.

The mystery of defining aortic valve area: what have we learnt from three-dimensional imaging modalities?

Aortic valve area is one of the main criteria used by echocardiography to determine the degree of valvular aortic stenosis, and it is calculated using the continuity equation which assumes that the flow volume of blood is equal at two points, the aortic valve area and the left ventricular outflow tract (LVOT). The main fallacy of this equation is the assumption that the LVOT area which is used to calculate the flow volume at the LVOT level is circular, where it is often an ellipse and sometimes irregular. The aim of this review is to explain the physiology of the continuity equation, the different sources of errors, the added benefits of using three-dimensional imaging modalities to measure LVOT area, the latest recommendations related to valvular aortic stenosis, and to introduce future perspectives. A literature review of studies comparing aortic valve area and LVOT area, after using three-dimensional data, has shown underestimation of both measurements when using the continuity equation. This has more impact on patients with discordant echocardiographic measurements when aortic valve area is disproportionate to haemodynamic measurements in assessing the degree of aortic stenosis. Although fusion imaging modalities of LVOT area can help in certain group of patients to address the issue of aortic valve area underestimation, further research on introducing a correction factor to the conventional continuity equation might be more rewarding, saving patients additional tests and potential radiation, with no clear evidence of cost-effectiveness.

Recommendations on the echocardiographic assessment of aortic valve stenosis: a focused update from the European Association of Cardiovascular Imaging and the American Society of Echocardiography

Echocardiography is the key tool for the diagnosis and evaluation of aortic stenosis. Because clinical decision-making is based on the echocardiographic assessment of its severity, it is essential that standards are adopted to maintain accuracy and consistency across echocardiographic laboratories. Detailed recommendations for the echocardiographic assessment of valve stenosis were published by the European Association of Echocardiography and the American Society of Echocardiography in 2009. In the meantime, numerous new studies on aortic stenosis have been published with particular new insights into the difficult subgroup of low gradient aortic stenosis making an update of recommendations necessary. The document focuses in particular on the optimization of left ventricular outflow tract assessment, low flow, low gradient aortic stenosis with preserved ejection fraction, a new classification of aortic stenosis by gradient, flow and ejection fraction, and a grading algorithm for an integrated and stepwise approach of artic stenosis assessment in clinical practice.

Evolving new concepts in the assessment of aortic stenosis

Echocardiography has been pivotal in evaluating aortic stenosis (AS) over the past several decades. Recent experience has shown a wide spectrum in the clinical presentation of AS. A better understanding of the underlying hemodynamic principles has resulted in emergence of new subtypes of AS. New treatment modalities have also been introduced, requiring precise evaluation of aortic valve (AV) pathology for implementation of these therapies. This review will discuss new concepts and indices in the use of echocardiography in patients with AS. Specifically, we will address the hemodynamic characteristics, clinical presentation, and management of normal-flow, high-gradient; paradoxical low-flow, low-gradient; and classical low-flow, low-gradient aortic stenoses.

Role of Transesophageal Echocardiography in the Diagnosis of Paradoxical Low Flow, Low Gradient Severe Aortic Stenosis

Background and Objectives

Prior studies indicate that up to 35% of cases of severe aortic stenosis (AS) have paradoxical low flow, low gradient despite preserved left ventricular ejection fraction (LVEF). However, error in left ventricular outflow tract (LVOT) diameter may lead to misclassification. Herein, we determined whether measurement of LVOT diameter by transesophageal echocardiography (TEE) results in reclassification of cases to non-severe AS.

Subjects and Methods

Patients with severe AS with aortic valve area (AVA) <1 cm² by transthoracic echocardiography (TTE) within 6 months were studied. Paradoxical low flow, low gradient was defined as mean Doppler gradient (MG) <40 mm Hg and stroke volume index (SVI) ≤35 mL/m². Preserved LVEF was defined as ≥0.50.

Results

Among 108 patients, 12 (15%) had paradoxical low flow, low gradient severe AS despite preserved LVEF based on TTE measurement. When LVOT diameter by TEE in 2D was used, only 5 (6.3%) patients had low flow, low gradient severe AS (p<0.001). Coefficients of variability for intraobserver and interobserver measurement of LVOT were <10%. However, the limits of agreement between TTE and TEE measurement of LVOT ranged from 0.43 cm (95% confidence interval [CI]: 0.36 to 0.5) to -0.31 cm (95% CI: -0.38 to -0.23).

Conclusion

TEE measured LVOT diameter may result in reclassification to moderate AS in some patients due to low prevalence of true paradoxical low flow, low gradient (PLFLG) severe AS.

Routine intra-operative trans-oesophageal echocardiography yields better outcomes in surgical repair of CHD

OBJECTIVES

Trans-oesophageal echocardiographic imaging is valuable in the pre- and post-operative evaluation of children and adults with CHD; however, the frequency by which trans-oesophageal echocardiography guides the intra-operative course of patients is unknown.

METHODS

We retrospectively reviewed 1748 intra-operative trans-oesophageal echocardiograms performed between 1 October, 2005 and 31 December, 2010, and found 99 cases (5.7%) that required return to bypass, based in part upon the intra-operative echocardiographic findings.

RESULTS

The diagnoses most commonly requiring further repair and subsequent imaging were mitral valve disease (20.9%), tricuspid valve disease (16.0%), atrioventricular canal defects (12.0%), and pulmonary valve disease (14.1%). The vast majority of those requiring immediate return to bypass benefited by avoiding subsequent operations and longer lengths of hospital stay. A total of 14 patients (0.8%) who received routine imaging required further surgical repair within 1 week, usually due to disease that developed over ensuing days. Patients who had second post-operative trans-oesophageal echocardiograms in the operating room rarely required re-operations, confirming the benefit of routine intra-operative imaging.

CONCLUSIONS

This study represents a large single institutional review of intra-operative trans-oesophageal echocardiography, and confirms its applicability in the surgical repair of patients with CHD. Routine imaging accurately identifies patients requiring further intervention, does not confer additional risk of mortality or prolonged length of hospital stay, and prevents subsequent operations and associated sequelae in a substantial subset of patients. This study demonstrates the utility of echocardiography in intra-operative monitoring of surgical repair and highlights patients who are most likely to require return to bypass, as well as the co-morbidities of such manipulations.

3D echocardiography in congenital heart disease: a valuable tool for the surgeon

Real-time 3D echocardiography has been used increasingly in the assessment of patients with congenital heart disease. A number of studies have confirmed that this modality can be used as a complementary method to delineate morphology and spatial relationships of simple and more complex congenital heart lesions during surgical planning. Communication between the echocardiographer and surgeon can be simplified as simulation of surgical views can be achieved, thus minimizing the potential for error related to mental reconstruction. This review summarizes the available evidence for the role of real-time 3D echocardiography in congenital heart disease as an imaging modality to assist surgeons.

Challenges in the echocardiographic assessment of aortic stenosis

Calcific aortic valve stenosis is common in the elderly. While history and examination can establish the diagnosis, determination of its severity typically requires echocardiography to define valve anatomy, measure stenosis severity and assess left ventricular response. The purpose of this review is to describe some of the commonly encountered challenges in the echocardiographic assessment of aortic stenosis. These include errors in the calculation of aortic valve area, assessment of aortic stenosis during atrial fibrillation, determining the presence of aortic stenosis in the setting of low transvalvular pressure gradients and discriminating other forms of obstruction to left ventricular ejection from aortic stenosis. Lastly, a review of how echocardiography is utilized to select patients for transcatheter aortic valve replacement is presented.

Quantitative Analysis of Aortic Valve Stenosis and Aortic Root Dimensions by Three-Dimensional Echocardiography in Patients Scheduled for Transcutaneous Aortic Valve Implantation

Accurate assessment of the aortic valve area (AVA) and evaluation of the aortic root are important for clinical decision-making in patients being considered for transcatheter aortic valve implantation (TAVI). Real-time three-dimensional transesophageal echocardiography (RT3D-TEE) provides accurate and reliable quantitative assessment of aortic valve stenosis and the aortic root. We performed two-dimensional transthoracic echocardiography (2D-TTE), real-time 2D transesophageal echocardiography (RT2D-TEE) and RT3D-TEE in 71 consecutive patients referred for TAVI. RT3D-TEE multiplanar reconstruction was used to measure aortic root parameters, including left ventricular outflow tract (LVOT) diameter and area, aortic annulus diameter, aortic annulus area, and AVA. RT3D-TEE methods for planimetry and the LVOT-derived continuity equation for the estimation of AVA showed a good correlation. As iatrogenic coronary ostium occlusion is a potentially life-threatening complication, we evaluated the distances from the aortic annulus to the coronary ostia using RT3D-TEE. Based on our findings, we conclude that the geometry of the aortic root and aortic valve can be reliably and feasibly evaluated using RT3D-TEE, which is important for protecting against potential complications of TAVI, such as underestimation of the size of the aortic annulus that can result in aortic regurgitation and dislocation of the valve, or overestimation can lead to annulus rupture.

Assessment of cyclic changes in the diameter of the aortic annulus using speckle-tracking trans-esophageal echocardiography

It is uncertain whether dynamic variation in the diameter of the aortic annulus occurs during the cardiac cycle in humans. The purpose of this study was to analyze cyclic changes of the aortic annulus using speckle-tracking trans-esophageal echocardiography. The subjects were 40 patients with aortic stenosis and 40 controls. Absolute and relative changes in the diameter of the aortic annulus and the times at which the maximum and minimum diameters occurred during the cardiac cycle were determined using speckle-tracking trans-esophageal echocardiography. The maximum and minimum diameters were 22.9 ± 2.7 and 20.0 ± 2.9 mm, respectively, in controls. The change in diameter of the aortic annulus was 2.9 ± 0.7 mm, and the relative change was 12.9 ± 3.5%. The maximum aortic annulus diameter was reached at the onset of aortic valve opening, and the minimum diameter occurred in the rapid filling phase. The change in diameter of the aortic annulus was significantly smaller (2.2 ± 0.6 mm vs. 2.9 ± 0.7 mm, p < 0.0001), and the time to reach the maximum diameter was significantly longer (98.5 ± 17.5 ms vs. 83.4 ± 18.2 ms, p = 0.0004), in the aortic stenosis group than in the control group. The study found that dynamic changes of the aortic annulus occur in the cardiac cycle and can be measured using speckle-tracking trans-esophageal echocardiography. We also found that aortic stenosis has an effect on the extent and timing of these changes. This suggests that accurate assessment of aortic annulus diameter requires consideration of the timing of the cardiac cycle.

Echocardiography in the era of multimodality cardiovascular imaging

Echocardiography remains the most frequently performed cardiac imaging investigation and is an invaluable tool for detailed and accurate evaluation of cardiac structure and function. Echocardiography, nuclear cardiology, cardiac magnetic resonance imaging, and cardiovascular-computed tomography comprise the subspeciality of cardiovascular imaging, and these techniques are often used together for a multimodality, comprehensive assessment of a number of cardiac diseases. This paper provides the general cardiologist and physician with an overview of state-of-the-art modern echocardiography, summarising established indications as well as highlighting advances in stress echocardiography, three-dimensional echocardiography, deformation imaging, and contrast echocardiography. Strengths and limitations of echocardiography are discussed as well as the growing role of real-time three-dimensional echocardiography in the guidance of structural heart interventions in the cardiac catheter laboratory.

Severe aortic valve stenosis with low-gradient and preserved ejection fraction: a misclassification issue?

INTRODUCTION AND OBJECTIVES

Low-gradient severe aortic stenosis with preserved ejection fraction is a controversial entity. Misclassification of valvulopathy severity could explain the inconsistencies reported in the prognosis of these patients. Planimetry of the aortic area using three-dimensional transesophageal echocardiography could clear up these doubts. The objectives were to assess the agreement between measurements of the valvular aortic area by continuity equation in transthoracic echocardiography and that obtained through planimetry with three-dimensional transesophageal echocardiography in low-gradient severe aortic stenosis patients.

METHODS

Cross-sectional descriptive study of consecutive patients referred due to severe aortic stenosis. Patients underwent transthoracic echocardiography and three-dimensional transesophageal echocardiography. Paradoxical low-gradient severe aortic stenosis was defined by the presence in the transthoracic echocardiography of aortic valve area<1 cm(2), mean ventricular gradient<40 mmHg, and ejection fraction ≥ 50%. Concordance between the two techniques was evaluated.

RESULTS

Of 212 consecutive severe aortic stenosis patients evaluated, 63 cases (29.7%) fulfilled the paradoxical low-gradient inclusion criteria. We obtained three-dimensional aortic valve planimetry in 61 (96.8%) of those patients. In 52 patients (85.2%), aortic valve area by transesophageal echocardiography was <1 cm(2). The intraclass correlation coefficient between the two methods was 0.505 (95% confidence interval, 0.290-0.671; P<.001).

CONCLUSIONS

Paradoxical low-gradient severe aortic stenosis is an actual entity, confirmed in 85% of cases evaluated by three-dimensional transesophageal echocardiography.

Current clinical applications of transthoracic three-dimensional echocardiography

The advent of three-dimensional echocardiography (3DE) has significantly improved the impact of non-invasive imaging on our understanding and management of cardiac diseases in clinical practice. Transthoracic 3DE enables an easier, more accurate and reproducible interpretation of the complex cardiac anatomy, overcoming the intrinsic limitations of conventional echocardiography. The availability of unprecedented views of cardiac structures from any perspective in the beating heart provides valuable clinical information and new levels of confidence in diagnosing heart disease. One major advantage of the third dimension is the improvement in the accuracy and reproducibility of chamber volume measurement by eliminating geometric assumptions and errors caused by foreshortened views. Another benefit of 3DE is the realistic en face views of heart valves, enabling a better appreciation of the severity and mechanisms of valve diseases in a unique, noninvasive manner. The purpose of this review is to provide readers with an update on the current clinical applications of transthoracic 3DE, emphasizing the incremental benefits of 3DE over conventional two-dimensional echocardiography.

[Functional cardiac MRI for assessment of aortic valve disease]

Aortic valve disease shows a rising incidence with the increasing mean age of Western populations. The detection of hemodynamic parameters, which transcends the mere assessment of valve morphology, has an important future potential concerning classification of the severity of disease. MRI allows a non-invasive and a spatially flexible view of the aortic valve and the adjacent anatomic region, left ventricular outflow tract (LVOT) and ascending aorta. Moreover, the technique allows the determination of functional hemodynamic parameters, such as flow velocities and effective orifice areas. The new approach of a serial systolic planimetry velocity-encoded MRI sequence (VENC-MRI) facilitates the sizing of blood-filled cardiac structures with the registration of changes in magnitude during systole. Additionally, the subvalvular VENC-MRI measurements improve the clinically important exact determination of the LVOT area with respect to its specific eccentric configuration and its systolic deformity.