Assessing aortic valve area in aortic stenosis by continuity equation: a novel approach using real-time three-dimensional echocardiography

Differentiation of the severity of rheumatic mitral stenosis using dimensionless index and its association with outcomes

Introduction

The severity of mitral stenosis (MS) is commonly assessed using mitral valve area (MVA) measured with transthoracic echocardiography (TTE). The dimensionless index (DI) of mitral valve (MV) was recently studied in degenerative MS. We evaluated DI MV in rheumatic MS and studied its relationship with clinical outcomes.

Methods

We studied 406 cases of rheumatic MS in a retrospective single centre cohort study, with 174 in a derivation cohort, 121 in a TTE validation cohort, and 111 in a transoesophageal echocardiography (TEE) validation cohort. DI MV was calculated by dividing the left ventricular outflow tract pulsed-wave Doppler time-velocity integral (TVI) by the MV continuous-wave Doppler TVI. DI MV was compared against MV area using the two-dimensional planimetry, pressure half-time and continuity equation methods, or, in the TEE validation cohort, TEE-derived three-dimensional planimetry. Severe MS was defined as an MV area ≤1.5 cm2. Outcomes pertaining to all-cause death and mitral valve intervention were studied in the former two cohorts.

Results

All-in-all, 231 patients (56.9 %) across the three cohorts had severe MS. In the derivation cohort, ROC analysis showed that DI MV could accurately classify MS severity (AUC = 0.838, 95 % CI, 0.780-0.897, p < 0.001). DI MV ≤ 0.25 and DI MV ≥ 0.40 had high specificity for identifying severe (93.7 %) and non-severe MS (93.7 %) respectively. In the validation cohorts, these respectively showed similar specificity for identifying severe (93.8 %) and non-severe MS (91.4 %). In the derivation and TTE validation cohorts, the median follow up duration was 6.32 years (interquartile range, 4.22-10.3 years) with 90 deaths (30.5 %) and 50 patients (17.0 %) undergoing MV intervention. DI MV was univariately significant (HR = 0.075, 95 % CI 0.0215-0.378, p = 0.002) in Cox regression for a composite outcome of death and MV intervention. DI MV remained independently associated with the composite outcome in multivariate analysis.

Conclusion

DI MV can help rule-in or rule-out severe MS with high specificity, and is independently associated with composite outcomes of death and MV intervention.

An Artificial Intelligence Algorithm for Detection of Severe Aortic Stenosis: A Clinical Cohort Study

Background

Identifying individuals with severe aortic stenosis (AS) at high risk of mortality remains challenging using current clinical imaging methods.

Objectives

The purpose of this study was to evaluate an artificial intelligence decision support algorithm (AI-DSA) to augment the detection of severe AS within a well-resourced health care setting.

Methods

Agnostic to clinical information, an AI-DSA trained to identify echocardiographic phenotype associated with an aortic valve area (AVA)<1 cm2 using minimal input data (excluding left ventricular outflow tract measures) was applied to routine transthoracic echocardiograms (TTE) reports from 31,141 U.S. Medicare beneficiaries at an academic medical center (2003-2017).

Results

Performance of AI-DSA to detect the phenotype associated with an AVA<1 cm2 was excellent (sensitivity 82.2%, specificity 98.1%, negative predictive value 9.2%, c-statistic = 0.986). In addition to identifying clinical severe AS cases, AI-DSA identified an additional 1,034 (3.3%) individuals with guideline-defined moderate AS but with a similar clinical and TTE phenotype to those with severe AS with low rates of aortic valve replacement (6.6%). Five-year mortality was 75.9% in those with known severe AS, 73.5% in those with a similar phenotype to severe AS, and 44.6% in those without severe AS. The AI-DSA continued to perform well to identify severe AS among those with a depressed left ventricular ejection fraction. Overall rates of aortic valve replacement remained low, even in those with an AVA<1 cm2 (21.9%).

Conclusions

Without relying on left ventricular outflow tract measurements, an AI-DSA used echocardiographic reports to reliably identify the phenotype of severe AS. These results suggest possible utility for this AI-DSA to enhance detection of severe AS individuals at risk for adverse outcomes.

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.

Impact of Net Atrioventricular Compliance on Mitral Valve Area Assessment-A Perspective Considering Three-Dimensional Mitral Valve Area by Transesophageal Echocardiography

BACKGROUND

Net atrioventricular compliance (Cn) can affect the accuracy of mitral valve area (MVA) assessment. We assessed how different methods of MVA assessment are affected by Cn, and if patients with abnormal Cn may be identified by clinical and/or echocardiographic parameters.

METHODS

We studied 244 patients with rheumatic MS. The concordance between mitral valve area (MVA) by 2D planimetry, pressure half-time (PHT), continuity equation (CE), Yeo's index, and 3-dimensional mitral valve area assessed by transesophageal echocardiography (TEE 3DMVA) in patients with normal and abnormal Cn (Cn ≤ 4 mL/mmHg) were evaluated in the 110 patients with both transesophageal echocardiogram (TEE) and transthoracic echocardiogram (TTE). Variables that were associated with abnormal Cn were validated in the remaining 134 patients with only TTE.

RESULTS

Except for MVA by CE, concordance with TEE 3DMVA was poorer for all other methods of MVA assessment in patients with abnormal Cn. But, the difference in concordance was only statistically significant for MVA by PHT. Patients with MVA ≤ 1.5 cm2 by 2D planimetry and PHT ≤ 130 ms were likely to have an abnormal Cn. (specificity 98.5%). This finding was validated in the remaining 134 patients (specificity 93%).

CONCLUSIONS

MVA assessment by PHT is significantly affected by Cn. Abnormal Cn should be suspected when 2D planimetry MVA is ≤1.5 cm2 together with an inappropriately short PHT that is ≤130 ms. In this scenario, MVA by PHT is inaccurate.

Combining 2D Planimetry and Yeo's Index Can Help Accurately Identify Patients with Severe Rheumatic Mitral Stenosis-A Perspective from a 3D Assessment Using Transoesophageal Echocardiography

BACKGROUND

Yeo's index is a novel measure of the severity of rheumatic mitral valve stenosis (MS). It is derived from the product of the mitral leaflet separation index and dimensionless index. This study aims to validate Yeo's index using a transesophageal echocardiogram (TEE) three-dimensional (3D) mitral valve area (MVA) as a comparator and to compare the concordance of existing echocardiographic measures of the MVA with TEE 3DMVA.

METHODS AND RESULTS

We studied 111 patients with rheumatic MS who underwent both transthoracic echocardiography (TTE) and a TEE assessment of MS severity. Yeo's index, the MVA determined by 2D planimetry, pressure half-time (PHT) and continuity equation (CE) measured on TTE were compared with the TEE 3DMVA. With a linear correlation, Yeo's index showed the best correlation with TEE 3DMVA (r2 = 0.775), followed by 2D planimetry (r2 = 0.687), CE (r2 = 0.598) and PHT (r2 = 0.363). Using TEE 3DMVA as comparator, Yeo's index (ρc = 0.739) demonstrated the best concordance, followed by 2D planimetry (ρc = 0.632), CE (ρc = 0.464) and PHT (ρc = 0.366). When both Yeo's index and 2D planimetry suggested significant MS, the positive predictive value was high (an AUC of 0.966 and a PPV of 100.00% for severe MS, and an AUC of 0.864 and a PPV of 85.71% for very severe MS). When both measures suggested the absence of significant MS, the negative predictive value was also high (an AUC of 0.940 and an NPV of 88.90% for severe MS, and an AUC of 0.831 and an NPV of 88.71% for very severe MS).

CONCLUSIONS

Yeo's index performed well in identifying severe MS when compared with TEE 3DMVA and may be a useful adjunct to existing methods of measuring MS severity. Combining it with 2D planimetry could further enhance its accuracy.

Diagnostic Challenges in Aortic Stenosis

Aortic stenosis (AS) is the most prevalent degenerative valvular disease in western countries. Transthoracic echocardiography (TTE) is considered, nowadays, to be the main imaging technique for the work-up of AS due to high availability, safety, low cost, and excellent capacity to evaluate aortic valve (AV) morphology and function. Despite the diagnosis of AS being considered straightforward for a very long time, based on high gradients and reduced aortic valve area (AVA), many patients with AS represent a real dilemma for cardiologist. On the one hand, the acoustic window may be inadequate and the TTE limited in some cases. On the other hand, a growing body of evidence shows that patients with low gradients (due to systolic dysfunction, concentric hypertrophy or coexistence of another valve disease such as mitral stenosis or regurgitation) may develop severe AS (low-flow low-gradient severe AS) with a similar or even worse prognosis. The use of complementary imaging techniques such as transesophageal echocardiography (TEE), multidetector computed tomography (MDTC), or cardiac magnetic resonance (CMR) plays a key role in such scenarios. The aim of this review is to summarize the diagnostic challenges associated with patients with AS and the advantages of a comprehensive multimodality cardiac imaging (MCI) approach to reach a precise grading of the disease, a crucial factor to warrant an adequate management of patients.

Yeo's index: A novel index that combines anatomic and haemodynamic assessment of the severity of mitral stenosis

BACKGROUND

A mitral leaflet separation index (MLSI), measuring the anatomical separation of the mitral valve (MV) leaflet tips in diastole, was previously described as an accurate method of assessing mitral stenosis (MS). We propose a novel modification of the MLSI by including a hemodynamic assessment which we term Yeo's index that may improve its diagnostic performance.

METHODS AND RESULTS

We retrospectively studied 174 patients with varying severity of MS without significant mitral regurgitation, aortic valve disease or ventricular septal defect. MLSI was measured in 2 orthogonal views on transthoracic echocardiography as previously described. MV dimensionless index (DI) was calculated by dividing the left ventricular outflow tract pulsed-wave Doppler time velocity integral (TVI) by the MV continuous-wave Doppler TVI. We defined Yeo's index as the product of MLSI and DI. With linear correlation, Yeo's index demonstrated good correlation against MVA by planimetry (r = 0.728), pressure half-time (r = 0.677), and continuity equation (r = 0.829), with improved performance over the MLSI. Using ROC analysis, Yeo's index demonstrated good ability to correctly classify MS as severe (MVA ≤1.5cm2) (AUC 0.874, 95% CI 0.816-0.920). Yeo's index ≤0.260 cm correctly classified severe MS with sensitivity of 82% and specificity of 80%. Presence of AF did not affect the performance of Yeo's index. Yeo's index ≤0.147 cm also identified very severe MS (MVA ≤ 1.0 cm2) with specificity of 94% and sensitivity of 78%.

CONCLUSION

Yeo's index performed well in identifying severe MS and may be a useful adjunct to existing measures of MS severity.

Changes in cerebral autoregulation and vasoreactivity after surgical aortic valve replacement: a prospective study

NEW FINDINGS

What is the central question of this study? How are dynamic cerebral autoregulation and brain vasoreactivity influenced by severe aortic stenosis and its surgical treatment? What are the main findings and their importance? Dynamic cerebral autoregulation is preserved in the long term in patients with severe aortic stenosis and does not change after surgical aortic valve replacement. However, carbon dioxide vasoreactivity is impaired in these patients.

ABSTRACT

Surgical aortic valve replacement (SAVR) alters the natural course of severe aortic stenosis (AS). In this study, we aimed to determine the effects of the disease on dynamic cerebral autoregulation and vasoreactivity (VR) and to assess their changes after SAVR. We recruited 23 patients diagnosed with severe AS eligible for SAVR and 15 healthy matched controls. AS patients had lower mean VR to CO2 (P = 0.005) than controls, but dynamic cerebral autoregulation was preserved. Cerebral haemodynamics showed no significant change after SAVR. Patients with smaller baseline aortic valve areas presented with smaller low frequency phase changes after surgery (P = 0.016). Severe AS does not seem to impact dynamic cerebral autoregulation but does reduce VR to CO2 . SAVR does not alter cerebral autoregulation nor vasoreactivity.

The role of 4-dimensional flow in the assessment of bicuspid aortic valve and its valvulo-aortopathies

Bicuspid aortic valve is the most common congenital cardiac malformation and the leading cause of aortopathy and aortic stenosis in younger patients. Aortic wall remodelling secondary to altered haemodynamic flow patterns, changes in peak velocity, and wall shear stress may be implicated in the development of aortopathy in the presence of bicuspid aortic valve and dysfunction. Assessment of these parameters as potential predictors of disease severity and progression is thus desirable. The anatomic and functional information acquired from 4D flow MRI can allow simultaneous visualisation and quantification of the pathological geometric and haemodynamic changes of the aorta. We review the current clinical utility of haemodynamic quantities including velocity, wall sheer stress and energy losses, as well as visual descriptors such as vorticity and helicity, and flow direction in assessing the aortic valve and associated aortopathies.

Core Lab Adjudication of the ACURATE neo2 Hemodynamic Performance Using Computed-Tomography-Corrected Left Ventricular Outflow Tract Area

(1) Background: Hemodynamic assessment of prosthetic heart valves using conventional 2D transthoracic Echocardiography-Doppler (2D-TTE) has limitations. Of those, left ventricular outflow tract (LVOT) area measurement is one of the major limitations of the continuity equation, which assumes a circular LVOT. (2) Methods: This study comprised 258 patients with severe aortic stenosis (AS), who were treated with the ACURATE neo2. The LVOT area and its dependent Doppler-derived parameters, including effective orifice area (EOA) and stroke volume (SV), in addition to their indexed values, were calculated from post-TAVI 2D-TTE. In addition, the 3D-LVOT area from pre-procedural MDCT scans was obtained and used to calculate corrected Doppler-derived parameters. The incidence rates of prosthesis patient mismatch (PPM) were compared between the 2D-TTE and MDCT-based methods (3) Results: The main results show that the 2D-TTE measured LVOT is significantly smaller than 3D-MDCT (350.4 ± 62.04 mm² vs. 405.22 ± 81.32 mm²) (95% Credible interval (CrI) of differences: −55.15, −36.09), which resulted in smaller EOA (2.25 ± 0.59 vs. 2.58 ± 0.63 cm²) (Beta = −0.642 (95%CrI of differences: −0.85, −0.43), and lower SV (73.88 ± 21.41 vs. 84.47 ± 22.66 mL), (Beta = −7.29 (95% CrI: −14.45, −0.14)), respectively. PPM incidence appears more frequent with 2D-TTE- than 3D-MDCT-corrected measurements (based on the EOAi) 8.52% vs. 2.32%, respectively. In addition, significant differences regarding the EOA among the three valve sizes (S, M and L) were seen only with the MDCT, but not on 2D-TTE. (4) Conclusions: The corrected continuity equation by combining the 3D-LVOT area from MDCT with the TTE Doppler parameters might provide a more accurate assessment of hemodynamic parameters and PPM diagnosis in patients treated with TAVI. The ACURATE neo2 THV has a large EOA and low incidence of PPM using the 3D-corrected LVOT area than on 2D-TTE. These findings need further confirmation on long-term follow-up and in other studies.

When Aortic Stenosis Is Not Alone: Epidemiology, Pathophysiology, Diagnosis and Management in Mixed and Combined Valvular Disease

Aortic stenosis (AS) may present frequently combined with other valvular diseases or mixed with aortic regurgitation, with peculiar physio-pathological and clinical implications. The hemodynamic interactions between AS in mixed or combined valve disease depend on the specific combination of valve lesions and may result in diagnostic pitfalls at echocardiography; other imaging modalities may be helpful. Indeed, diagnosis is challenging because several echocardiographic methods commonly used to assess stenosis or regurgitation have been validated only in patients with the single-valve disease. Moreover, in the developed world, patients with multiple valve diseases tend to be older and more fragile over time; also, when more than one valvular lesion needs to address the surgical risk rises together with the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. Therefore, when AS presents mixed or combined valve disease, the heart valve team must integrate various parameters into the diagnosis and management strategy, including suitability for single or multiple transcatheter valve procedures. This review aims to summarize the most critical pathophysiological mechanisms underlying AS when associated with mitral regurgitation, mitral stenosis, aortic regurgitation, and tricuspid regurgitation. We will focus on echocardiography, clinical implications, and the most important treatment strategies.

Complex and multilevel left ventricular outflow tract obstruction: What can 3D echocardiography add?

Background

Subaortic obstruction by a membrane or systolic anterior motion of the mitral valve leaflets is usually suspected in young patients, especially if the anatomy of the aortic valve is not clearly stenotic and unexplained left ventricular hypertrophy exists in the context of high transaortic gradients.

Main body

In certain circumstances, some patients show both aortic and subaortic stenotic lesions of variable severity. Doppler echocardiography can help in grading severity in the case of single-level obstruction but not in patients with multilevel obstruction where the continuity equation is of no value. Three-dimensional (3D) echocardiography allows "en-face" visualization of each level of the aortic valve and subaortic tract; in addition, direct planimetry of the areas can be done using multiplanar reformatting.

Conclusions

Accordingly, 3D echocardiography plays a crucial role in the assessment in patients with multilevel left ventricular outflow tract obstruction as it can accurately delineate the location and size, and severity of the stenosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43044-021-00197-y.

Discrepancy of Aortic Valve Area Measurements by Doppler vs. Biplane Stroke Volume Measurements and Utility of Combining the Different Areas in Aortic Valve Stenosis - The Asian Valve Registry

BACKGROUND

The aortic valve area index (AVAI) in aortic stenosis (AS) is measured by echocardiography with a continuity equation using the stroke volume index by Doppler (SVIDoppler) or biplane Simpson (SVIBiplane) method. AVAIDopplerand AVAIBiplaneoften show discrepancy due to differences between SVIDopplerand SVIBiplane. The degree of discrepancy and utility of combined AVAIs have not been investigated in a large population of AS patients, and the characteristics of subjects with larger discrepancies are unknown.

METHODS AND RESULTS

We studied 820 patients with significant AS (AVADoppler<1.5 cm2) enrolled in the Asian Valve Registry, a prospective multicenter registry at 12 Asian centers. All-cause death and aortic valve replacement were defined as events. SVIDopplerwas significantly larger than SVIBiplane(49±11 vs. 39±11 mL/m2, P<0.01) and AVAIDopplerwas larger than AVAIBiplane(0.51±0.15 vs. 0.41±0.14 cm2/m2, P<0.01). An increase in (AVAIDoppler- AVAIBiplane) correlated with shorter height, lower weight, older age, smaller left ventricular (LV) diameter and increased velocity of ejection flow at the LV outflow tract. Severe AS by AVAIDoppleror AVAIBiplaneenabled prediction of events, and combining these AVAIs improved the predictive value of each.

CONCLUSIONS

Discrepancy in AVAI by Doppler vs. biplane method was significantly more pronounced with increased LV outflow tract flow velocity, shorter height, lower weight, older age and smaller LV cavity dimensions. Combining the AVAIs enabled mutual and incremental value in predicting events.

Transvalvular Flow Rate Determines Prognostic Value of Aortic Valve Area in Aortic Stenosis

BACKGROUND

Aortic valve area (AVA) ≤1.0 cm² is a defining characteristic of severe aortic stenosis (AS). AVA can be underestimated at low transvalvular flow rate. Yet, the impact of flow rate on prognostic value of AVA ≤1.0 cm² is unknown and is not incorporated into AS assessment.

OBJECTIVES

This study aimed to evaluate the effect of flow rate on prognostic value of AVA in AS.

METHODS

In total, 1,131 patients with moderate or severe AS and complete clinical follow-up were included as part of a longitudinal database. The effect of flow rate (ratio of stroke volume to ejection time) on prognostic value of AVA ≤1.0 cm² for time to death was evaluated, adjusting for confounders. Sensitivity analysis was performed to identify the optimal cutoff for prognostic threshold of AVA. The findings were validated in a separate external longitudinal cohort of 939 patients.

RESULTS

Flow rate had a significant effect on prognostic value of AVA. AVA ≤1.0 cm² was not prognostic for mortality (p = 0.15) if AVA was measured at flow rates below median (≤242 ml/s). In contrast, AVA ≤1.0 cm² was highly prognostic for mortality (p = 0.003) if AVA was measured at flow rates above median (>242 ml/s). Findings were irrespective of multivariable adjustment for age, sex, and surgical/transcatheter aortic valve replacement (as time-dependent covariates); comorbidities; medications; and echocardiographic features. AVA ≤1.0 cm² was also not an independent predictor of mortality below median flow rate in the validation cohort. The optimal flow rate cutoff for prognostic threshold was 210 ml/s.

CONCLUSIONS

Transvalvular flow rate determines prognostic value of AVA in AS. AVA measured at low flow rate is not a good prognostic marker and therefore not a good diagnostic marker for truly severe AS. Flow rate assessment should be incorporated into clinical diagnosis, classification, and prognosis of AS.

Comparison of flow-independent parameters for grading severity of aortic stenosis using intraoperative transesophageal echocardiography - A prospective observational study

Introduction

Discrepancies have been reported in grading of severity of aortic stenosis. We propose to compare Aortic valve area by continuity equation, Dimensionless Index and Acceleration time/Ejection time in patients with documented severe aortic stenosis with normal left ventricular function by TEE after induction of anesthesia. This might give use insight about the best parameter we can rely on intra-operatively for decision making.

Methodology

60 patients with severe AS undergoing elective cardiac surgery were enrolled in our study. Post intubation trans-thoracic echocardiography (TEE) was performed and above mentioned parameters was noted.

Results

96.7 % of patients continued in severe AS category when AS was measured using AVA as echo parameter. So there is 3.3 % disparity. There was disparity in 13.3% of cases when DI was considered. And there was 43.3% disparity when AT/ET was considered.

Conclusion

Perioperative grading of aortic stenosis continues to be a challenge for cardiac anesthesiologists. Multiple echocardiographic parameters have to be considered. We have found AVA and DI to have less disparity compared to AT/ET.

Quantification of aortic valve area: comparison of different methods of echocardiography with 3-D scan of the excised valve

Accurate determination of severity of aortic valve stenosis (AS) by aortic valve area (AVA) is essential for choosing the best treatment strategy. We compared AVA quantified by 4 different in vivo echocardiographic methods with AVA measured by 3D ex vivo scanning of the excised AV. The data on 38 patients who underwent aortic valve replacement were assessed. The AVA was determined by 4 echocardiographic methods of planimetry in 2D transesophageal echocardiography [planimetry (2D-TEE)], plainemetry by multiplanar reconstruction approach in 3D transesophageal echocardiography [MPR (3D-TEE)], and two continuity equation (CE) approaches; conventional CE (2D-TTE) in which left ventricular outflow tract [LVOT] area derived by LVOT diameter obtained in 2D transthoracic echocardiography and CE (3D-TEE) in which LVOT area obtained by 3D MPR. After the surgical removal of the AV, AVA was determined by 3D ex vivo scanning. Lowest AVA mean difference with 3D ex vivo scanning was found between CE (2D-TTE), followed by CE (3D-TEE). Planimetry (2D-TEE) in male patients as well as severely and non-severely calcified valves revealed a significant higher AVA mean difference with 3D ex vivo scanning than CE (2D-TTE) and CE (3D-TEE) methods. However, with a nonsignificant effect, CE (2D-TTE) and planimetry (2D-TEE) had the least mean difference with 3D ex vivo scanning possibly due to less frequent bicuspid AV in females. CE (2D-TTE) was more accurate than other methods of AVA calculation. Moreover, CE (3D-TEE) and MPR (3D-TEE) methods had acceptable accuracy in comparison with planimetry (2D-TEE) for definition of AS severity.

Left ventricular outflow tract velocity time integral in hospitalized heart failure with preserved ejection fraction

Aims

The prognostic implication of left ventricular outflow tract velocity time integral (LVOT‐VTI) on admission in hospitalized heart failure with preserved ejection fraction (HFpEF) patients has not been determined. We sought to investigate whether LVOT‐VTI on admission is associated with worse clinical outcomes in hospitalized patients with HFpEF.

Methods and results

We studied consecutive 214 hospitalized HFpEF patients who had accessible LVOT‐VTI data on admission, from a prospective HFpEF‐specific multicentre registry. The primary outcome of interest was the composite of all‐cause death and readmission due to heart failure. During a median follow‐up period of 688 (interquartile range 162–810) days, the primary outcome occurred in 83 patients (39%). The optimal cut‐off value of LVOT‐VTI for the primary outcome estimated by receiver operating characteristic analysis was 15.8 cm. Lower LVOT‐VTI was significantly associated with the primary outcome compared with higher LVOT‐VTI (P = 0.005). Multivariable Cox regression analyses revealed that lower LVOT‐VTI was an independent determinant of the primary outcome (hazard ratio 0.94, 95% confidence interval 0.91–0.98). In multivariable linear regression, haemoglobin level was the strongest independent determinant of LVOT‐VTI among clinical parameters (β coefficient = −0.61, P = 0.007). Furthermore, patients with lower LVOT‐VTI and anaemia had the worst clinical outcomes among the groups (P < 0.001).

Conclusions

Lower admission LVOT‐VTI was an independent determinant of worse clinical outcomes in hospitalized HFpEF patients, indicating that LVOT‐VTI on admission might be useful for categorizing a low‐flow HFpEF phenotype and risk stratification in hospitalized HFpEF patients.

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.

Value of ejection fraction/velocity ratio in the prognostic stratification of patients with asymptomatic aortic valve stenosis

BACKGROUND

The ejection fraction/velocity ratio (EFVR) is a simple function-corrected index of aortic stenosis severity with a good correlation with aortic valve area measured using the Gorlin formula at cardiac catheterization. It is calculated by dividing left ventricular ejection fraction (LVEF) to 4 × (peak jet velocity)² .

OBJECTIVE

Our aim was to evaluate the value of EFVR in predicting adverse events in patients with asymptomatic aortic stenosis.

METHODS

We analyzed the clinical and echocardiographic data of 216 asymptomatic patients with at least moderate aortic stenosis (AVA ≤ 1.5 cm² ). The primary end-point was cardiovascular death or aortic valve replacement.

RESULTS

There were 119 (55%) men and mean age was 68 ± 10 years. The mean follow-up time was 4.2 ± 1.6 years (median 4.3 years). During follow-up, the composite end-point of death or aortic valve replacement was reached in 105 patients (49%). Using multivariate Cox regression analysis, EFVR and valvulo-arterial impedance emerged as independent variables associated with outcome (P < 0.001 and P = 0.001, respectively). In the subgroup of patients with severe aortic stenosis (AVA < 1 cm² ), EFVR ≤ 0.9 was associated with an increased hazard ratio for the composite end-point of mortality and aortic valve replacement (HR 2.14, 95% CI: 1.15-4.0, P = 0.017), even after adjusting for aortic valve area.

CONCLUSIONS

In patients with asymptomatic moderate to severe aortic stenosis, EFVR is useful for risk stratification. Our results suggest that incorporating EFVR in the evaluation of patients with asymptomatic aortic stenosis might help identify those who are most likely to benefit from early elective aortic replacement.

Surgical as Opposed to Transcatheter Aortic Valve Replacement Improves Basal Interventricular Septal Hypertrophy

BACKGROUND

Basal interventricular septum (IVS) hypertrophy (BSH) with reduced basal IVS contraction and IVS-aorta angle is frequently associated with aortic stenosis (AS). BSH shape suggests compression by the longitudinally elongated ascending aorta, causing basal IVS thickening and contractile dysfunction, further suggesting the possibility of aortic wall shortening to improve the BSH. Surgical aortic valve replacement (SAVR), as opposed to transcatheter AVR (TAVR), includes aortic wall shortening by incision and stitching on the wall and may potentially improve BSH. We hypothesized that BSH configuration and its contraction improves after SAVR in patients with AS.

METHODS AND RESULTS

In 32 patients with SAVR and 36 with TAVR for AS, regional wall thickness and systolic contraction (longitudinal strain) of 18 left ventricular (LV) segments, and IVS-aorta angle were measured on echocardiography. After SAVR, basal IVS/average LV wall thickness ratio, basal IVS strain, and IVS-aorta angle significantly improved (1.11±0.24 to 1.06±0.17; -6.2±5.7 to -9.1±5.2%; 115±22 to 123±14°, P<0.001, respectively). Contractile improvement in basal IVS was correlated with pre-SAVR BSH (basal IVS/average LV wall thickness ratio or IVS-aorta angle: r=0.47 and 0.49, P<0.01, respectively). In contrast, BSH indices did not improve after TAVR.

CONCLUSIONS

In patients with AS, SAVR as opposed to TAVR improves associated BSH and its functional impairment.

Geometry of the left ventricular outflow tract assessed by 3D TEE in patients with aortic stenosis: impact of upper septal hypertrophy on measurements of Doppler-derived left ventricular stroke volume

BACKGROUND

It is unclear how upper septal hypertrophy (USH) affects Doppler-derived left ventricular stroke volume (SV) in patients with AS. The aims of this study were to: (1) validate the accuracy of 3D transesophageal echocardiography (TEE) measurements of the left ventricular outflow tract (LVOT), (2) evaluate the differences in LVOT geometry between AS patients with and without USH, and (3) assess the impact of USH on measurement of SV.

METHODS

In protocol 1, both 3D TEE and multi-detector computed tomography were performed in 20 patients with AS [aortic valve area (AVA) ≤ 1.5 cm²]. Multiplanar reconstruction was used to measure the LVOT short and long diameters in four parts from the tip of the septum to the annulus. In protocol 2, the same 3D TEE measurements were performed in AS patients (AVA ≤ 1.5 cm², n = 129) and controls (n = 30). We also performed 2D and 3D transthoracic echocardiography in all patients.

RESULTS

In protocol 1, excellent correlations of LVOT parameters were found between the two modalities. In protocol 2, the USH group had smaller LVOT short and long diameters than the non-USH group. Although no differences in mean pressure gradient, or SV calculated with the 3D method existed between the two groups, the USH group had greater SV calculated with the Doppler method (73 ± 15 vs. 66 ± 15 ml) and aortic valve area (0.89 ± 0.26 vs. 0.73 ± 0.24 cm²) than the non-USH group.

CONCLUSIONS

3D TEE can provide a precise assessment of the LVOT in AS. USH affects the LVOT geometry in patients with AS, which might lead to inaccurate assessments of disease severity.

Anatomic estimation of aortic stenosis severity vs "fusion" of data from computed tomography and Doppler echocardiography

AIM

Two-dimensional, transthoracic echocardiography does not account for the noncircular anatomy of the left ventricular outflow tract (LVOT) and may therefore underestimate LVOT area. Fusion of computed tomography (CT)-derived LVOT area and Doppler-derived flow data has been proposed to improve assessment of aortic valve area (AVA) and classification of aortic stenosis severity. For hemodynamic reasons, effective AVA has to be smaller than anatomic AVA. The aim of the study was to test the "fusion approach" by comparing effective CT-derived AVA with anatomic AVA from CT planimetry.

METHODS AND RESULTS

Data of 244 consecutive patients (mean age 81 ± 5 years, 61% female) with aortic stenosis were retrospectively analyzed comparing effective AVA (calculated from the continuity equation using CT-LVOT and transthoracic Doppler measurements) with anatomic AVA based on CT planimetry. Substituting the LVOT area from transthoracic echocardiography (TTE) by the CT-LVOT resulted in an increase in AVA from 0.74 ± 0.15 to 0.92 ± 0.18cm² (P < .01), which was larger than anatomic AVA (0.82 ± 0.15cm²). Similar results were obtained based on planimetry from transesophageal echocardiography (TEE; AVA 0.79 ± 0.14cm², P < .01 vs CT-LVOT) and in the subgroup presenting with low-gradient severe aortic stenosis and preserved ejection fraction (n = 67, AVA from TTE 0.76 ± 0.09; from CT-LVOT 0.97 ± 0.14; CT planimetry 0.86 ± 0.12; TEE planimetry 0.82 ± 0.13cm²).

CONCLUSION

Fusion of CT-derived LVOT area with Doppler echocardiography results in a calculated effective AVA that is larger than the corresponding anatomic AVA. Therefore, adjustment of partition values may be warranted when using this approach.

Quantification of the area and shunt volume of multiple, circular, and noncircular ventricular septal defects: A 2D/3D echocardiography comparison and real time 3D color Doppler feasibility determination study

BACKGROUND

Quantification of defect size and shunt flow is an important aspect of ventricular septal defect (VSD) evaluation. This study compared three-dimensional echocardiography (3DE) with the current clinical standard two-dimensional echocardiography (2DE) for quantifying defect area and tested the feasibility of real time 3D color Doppler echocardiography (RT3D-CDE) for quantifying shunt volume of irregular shaped and multiple VSDs.

METHODS

Latex balloons were sutured into the ventricles of 32 freshly harvested porcine hearts and were connected with tubing placed in septal perforations. Tubing was varied in area (0.13-5.22 cm²), number (1-3), and shape (circle, oval, crescent, triangle). A pulsatile pump was used to pump "blood" through the VSD (LV to RV) at stroke volumes of 30-70 mL with a stroke rate of 60 bpm. Two-dimensional echocardiography (2DE), 3DE, and RT3D-CDE images were acquired from the right side of the phantom.

RESULTS

For circular VSDs, both 2DE and 3DE area measurements were consistent with the actual areas (R² = 0.98 vs 0.99). For noncircular/multiple VSDs, 3DE correlated with the actual area more closely than 2DE (R² = 0.99 vs 0.44). Shunt volumes obtained using RT3D-CDE positively correlated with pumped stroke volumes (R² = 0.96).

CONCLUSIONS

Three-dimensional echocardiography (3DE) is a feasible method for determining VSD area and is more accurate than 2DE for evaluating the area of multiple or noncircular VSDs. Real-time 3D color Doppler echocardiography (RT3D-CDE) is a feasible method for quantifying the shunt volume of multiple or noncircular VSDs.

Aortic Stenosis, a Left Ventricular Disease: Insights from Advanced Imaging

Aortic stenosis (AS) is the most common primary valve disorder in the elderly with an increasing prevalence. It is increasingly clear that it is also a disease of the left ventricle (LV) rather than purely the aortic valve. The transition from left ventricular hypertrophy to fibrosis results in the eventual adverse effects on systolic and diastolic function. Appropriate selection of patients for aortic valve intervention is crucial, and current guidelines recommend aortic valve replacement in severe AS with symptoms or in asymptomatic patients with left ventricular ejection fraction (LVEF) <50 %. LVEF is not a sensitive marker and there are other parameters used in multimodality imaging techniques, including longitudinal strain, exercise stress echo and cardiac MRI that may assist in detecting subclinical and subtle LV dysfunction. These findings offer potentially better ways to evaluate patients, time surgery, predict recovery and potentially offer targets for specific therapies. This article outlines the pathophysiology behind the LV response to aortic stenosis and the role of advanced multimodality imaging in describing it.

[Real-time 3D echocardiography for estimation of severity in valvular heart disease : Impact on current guidelines]

Besides providing spatial anatomic information on heart valves, real-time three-dimensional echocardiography (3DE) combined with color Doppler has the potential to overcome the limitations of flow quantification inherent to conventional 2D color Doppler methods. Recent studies validated the application of color Doppler 3DE (cD-3DE) for the quantification of regurgitation flow based on the vena contracta area (VCA) and the proximal isovelocity surface area (PISA) methods. Particularly the assessment of VCA by cD-3DE led to a change of paradigm by understanding of the VCA as being strongly asymmetric in the majority of patients and etiologies. This review provides a comprehensive description of the different concepts of cD-3DE-based flow quantification in the setting of different valvular heart diseases and their presentation in recent guidelines.

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.

Integrated strategy for in vitro characterization of a bileaflet mechanical aortic valve

Background

Haemodynamic performance of heart valve prosthesis can be defined as its ability to fully open and completely close during the cardiac cycle, neither overloading heart work nor damaging blood particles when passing through the valve. In this perspective, global and local flow parameters, valve dynamics and blood damage safety of the prosthesis, as well as their mutual interactions, have all to be accounted for when assessing the device functionality. Even though all these issues have been and continue to be widely investigated, they are not usually studied through an integrated approach yet, i.e. by analyzing them simultaneously and highlighting their connections.

Results

An in vitro test campaign of flow through a bileaflet mechanical heart valve (Sorin Slimline 25 mm) was performed in a suitably arranged pulsatile mock loop able to reproduce human systemic pressure and flow curves. The valve was placed in an elastic, transparent, and anatomically accurate model of healthy aorta, and tested under several pulsatile flow conditions. Global and local hydrodynamics measurements and leaflet dynamics were analysed focusing on correlations between flow characteristics and valve motion. The haemolysis index due to the valve was estimated according to a literature power law model and related to hydrodynamic conditions, and a correlation between the spatial distribution of experimental shear stress and pannus/thrombotic deposits on mechanical valves was suggested. As main and general result, this study validates the potential of the integrated strategy for performance assessment of any prosthetic valve thanks to its capability of highlighting the complex interaction between the different physical mechanisms that govern transvalvular haemodynamics.

Conclusions

We have defined an in vitro procedure for a comprehensive analysis of aortic valve prosthesis performance; the rationale for this study was the belief that a proper and overall characterization of the device should be based on the simultaneous measurement of all different quantities of interest for haemodynamic performance and the analysis of their mutual interactions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12938-017-0314-2) contains supplementary material, which is available to authorized users.

Role of Echocardiography Before Transcatheter Aortic Valve Implantation (TAVI)

Aortic stenosis (AS) is the most common primary valve disorder in the elderly with an increasing prevalence; transcatheter aortic valve implantation (TAVI) has become an accepted alternative to surgical aortic valve replacement (AVR) in the high risk or inoperable patient. Appropriate selection of patients for TAVI is crucial and requires a multidisciplinary approach including cardiothoracic surgeons, interventional cardiologists, anaesthetists, imaging experts and specialist nurses. Multimodality imaging including echocardiography, CT and MRI plays a pivotal role in the selection and planning process; however, echocardiography remains the primary imaging modality used for patient selection, intra-procedural guidance, post-procedural assessment and long-term follow-up. The contribution that contemporary transthoracic and transoesophageal echocardiography make to the selection and planning of TAVI is described in this article.

Reliability of Aortic Stenosis Severity Classified by 3-Dimensional Echocardiography in the Prediction of Cardiovascular Events

The estimation of aortic valve area (AVA) by Doppler echocardiography-derived left ventricular stroke volume (LVSV) remains controversial. We hypothesized that AVA estimated from directly measured LVSV by 3-dimensional echocardiography (3DE) on the continuity equation might be more accurate in classifying aortic stenosis (AS) severity. We retrospectively enrolled 265 patients with moderate-to-severe AS with preserved ejection fraction. Indexed AVA (iAVA) was calculated using LVSV derived by 2D Doppler (iAVADop), Simpson's method (iAVASimp), and 3DE (iAVA3D). During a median follow-up period of 397 days (interquartile range 197 to 706 days), 135 patients experienced the composite end point (cardiac death 9%, aortic valve replacement 24%, and cardiovascular event 27%). Estimated iAVA3D and iAVASimp were significantly smaller than iAVADop and moderately correlated with peak aortic jet velocity. Upper septal hypertrophy was a major cause of discrepancy between iAVADop and iAVA3D methods. Based on the optimal cut-off point of iAVA for predicting peak aortic jet velocity >4.0 m/s, 141 patients (53%) were classified as severe AS and 124 patients (47%) as moderate AS by iAVADop. Indexed AVA3D classified 118 patients (45%) as severe and 147 patients (55%) as moderate AS. Of the 124 patients with moderate AS by iAVADop, 22 patients (18%) were reclassified as severe AS by iAVA3D and showed poor prognosis (hazard ratio 2.7, 95% CI 1.4 to 5.0; p = 0.001). In conclusion, 3DE might be superior in classifying patients with AS compared with Doppler method, particularly in patients with upper septal hypertrophy.

Quantification of Shunt Volume Through Ventricular Septal Defect by Real-Time 3-D Color Doppler Echocardiography: An in Vitro Study

Quantification of shunt volume is important for ventricular septal defects (VSDs). The aim of the in vitro study described here was to test the feasibility of using real-time 3-D color Doppler echocardiography (RT3-D-CDE) to quantify shunt volume through a modeled VSD. Eight porcine heart phantoms with VSDs ranging in diameter from 3 to 25 mm were studied. Each phantom was passively driven at five different stroke volumes from 30 to 70 mL and two stroke rates, 60 and 120 strokes/min. RT3-D-CDE full volumes were obtained at color Doppler volume rates of 15, 20 and 27 volumes/s. Shunt flow derived from RT3-D-CDE was linearly correlated with pump-driven stroke volume (R = 0.982). RT3-D-CDE-derived shunt volumes from three color Doppler flow rate settings and two stroke rate acquisitions did not differ (p > 0.05). The use of RT3-D-CDE to determine shunt volume though VSDs is feasible. Different color volume rates/heart rates under clinically/physiologically relevant range have no effect on VSD 3-D shunt volume determination.

Update: Cardiac Imaging (II). Transcatheter Aortic Valve Replacement: Advantages and Limitations of Different Cardiac Imaging Techniques

Transcatheter aortic valve replacement is an established therapy for patients with symptomatic severe aortic stenosis and contraindications or high risk for surgery. Advances in prostheses and delivery system designs and continuous advances in multimodality imaging, particularly the 3-dimensional techniques, have led to improved outcomes with significant reductions in the incidence of frequent complications such as paravalvular aortic regurgitation. In addition, data on prosthesis durability are accumulating. Multimodality imaging plays a central role in the selection of patients who are candidates for transcatheter aortic valve replacement, procedure planning and guidance, and follow-up of prosthesis function. The strengths and limitations of each imaging technique for transcatheter aortic valve replacement will be discussed in this update article.

Semiautomatic, Quantitative Measurement of Aortic Valve Area Using CTA: Validation and Comparison with Transthoracic Echocardiography

Objective. The aim of this work was to develop a fast and robust (semi)automatic segmentation technique of the aortic valve area (AVA) MDCT datasets. Methods. The algorithm starts with detection and cropping of Sinus of Valsalva on MPR image. The cropped image is then binarized and seed points are manually selected to create an initial contour. The contour moves automatically towards the edge of aortic AVA to obtain a segmentation of the AVA. AVA was segmented semiautomatically and manually by two observers in multiphase cardiac CT scans of 25 patients. Validation of the algorithm was obtained by comparing to Transthoracic Echocardiography (TTE). Intra- and interobserver variability were calculated by relative differences. Differences between TTE and MDCT manual and semiautomatic measurements were assessed by Bland-Altman analysis. Time required for manual and semiautomatic segmentations was recorded. Results. Mean differences from TTE were −0.19 (95% CI: −0.74 to 0.34) cm² for manual and −0.10 (95% CI: −0.45 to 0.25) cm² for semiautomatic measurements. Intra- and interobserver variability were 8.4 ± 7.1% and 27.6 ± 16.0% for manual, and 5.8 ± 4.5% and 16.8 ± 12.7% for semiautomatic measurements, respectively. Conclusion. Newly developed semiautomatic segmentation provides an accurate, more reproducible, and faster AVA segmentation result.

Moderate Aortic Stenosis and Coronary Artery Bypass Grafting: Clinical Update for the Perioperative Echocardiographer

Incidental aortic stenosis in the setting of coronary artery bypass surgery may be a perioperative challenge. The accurate assessment of the degree of aortic stenosis remains an important determinant. Although severe aortic stenosis is an indication for valve replacement, current guidelines advise a balanced approach to the management of moderate aortic stenosis in this setting. Multiple factors should be considered in a team discussion to balance risks versus benefits for the various management options in the given patient. The rapid progress in aortic valve technologies also offer alternatives for definitive management of moderate aortic stenosis in this setting that will likely become even safer in the near future.

Impact and predictors of noncircular left ventricular outflow tract shapes on estimating aortic stenosis severity by means of continuity equations

Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined. In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area. We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry (1.28 ± 0.55 cm(2)) was underestimated by the standard method (1.05 ± 0.47 cm(2); P=0.001), but not by the modified method. Congenital AV morphology and low cardiac index were the only multivariate predictors of horizontal-oval shape. Low cardiac index was the only predictor of noncircular shape. More than half our patients with AS had noncircular LVOTs. Using the modified method reduces mischaracterizations of AS severity. Congenital AV morphology and low cardiac index predict horizontal-oval or noncircular shape. These data suggest the value of direct LVOT measurement to calculate AS severity in patients who have congenital AV or a low cardiac index.

Role of modern 3D echocardiography in valvular heart disease

Three-dimensional (3D) echocardiography has been conceived as one of the most promising methods for the diagnosis of valvular heart disease, and recently has become an integral clinical tool thanks to the development of high quality real-time transesophageal echocardiography (TEE). In particular, for mitral valve diseases, this new approach has proven to be the most unique, powerful, and convincing method for understanding the complicated anatomy of the mitral valve and its dynamism. The method has been useful for surgical management, including robotic mitral valve repair. Moreover, this method has become indispensable for nonsurgical mitral procedures such as edge to edge mitral repair and transcatheter closure of paravaluvular leaks. In addition, color Doppler 3D echo has been valuable to identify the location of the regurgitant orifice and the severity of the mitral regurgitation. For aortic and tricuspid valve diseases, this method may not be quite as valuable as for the mitral valve. However, the necessity of 3D echo is recognized for certain situations even for these valves, such as for evaluating the aortic annulus for transcatheter aortic valve implantation. It is now clear that this method, especially with the continued development of real-time 3D TEE technology, will enhance the diagnosis and management of patients with these valvular heart diseases.

Clinical application of three-dimensional echocardiography

Echocardiography is one of the most valuable diagnostic tools in cardiology. Technological advances in ultrasound, computer and electronics enables three-dimensional (3-D) imaging to be a clinically viable modality which has significant impact on diagnosis, management and interventional procedures. Since the inception of 3D fully-sampled matrix transthoracic and transesophageal technology it has enabled easier acquisition, immediate on-line display, and availability of on-line analysis for the left ventricle, right ventricle and mitral valve. The use of 3D TTE has mainly focused on mitral valve disease, left and right ventricular volume and functional analysis. As structural heart disease procedures become more prevalent, 3D TEE has become a requirement for preparation of the procedure, intra-procedural guidance as well as monitoring for complications and device function. We anticipate that there will be further software development, improvement in image quality and workflow.

Echocardiographic reference ranges for normal cardiac chamber size: results from the NORRE study

AIMS

Availability of normative reference values for cardiac chamber quantitation is a prerequisite for accurate clinical application of echocardiography. In this study, we report normal reference ranges for cardiac chambers size obtained in a large group of healthy volunteers accounting for gender and age. Echocardiographic data were acquired using state-of-the-art cardiac ultrasound equipment following chamber quantitation protocols approved by the European Association of Cardiovascular Imaging.

METHODS

A total of 734 (mean age: 45.8 ± 13.3 years) healthy volunteers (320 men and 414 women) were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. A comprehensive echocardiographic examination was performed on all subjects following pre-defined protocols. There were no gender differences in age or cholesterol levels. Compared with men, women had significantly smaller body surface areas, and lower blood pressure. Quality of echocardiographic data sets was good to excellent in the majority of patients. Upper and lower reference limits were higher in men than in women. The reference values varied with age. These age-related changes persisted for most parameters after normalization for the body surface area.

CONCLUSION

The NORRE study provides useful two-dimensional echocardiographic reference ranges for cardiac chamber quantification. These data highlight the need for body size normalization that should be performed together with age-and gender-specific assessment for the most echocardiographic parameters.