Real-time three-dimensional echocardiography in aortic stenosis: a novel, simple, and reliable method to improve accuracy in area calculation

The robustness of the flow-gradient classification of severe aortic stenosis

Objectives

A flow-gradient classification is used to determine the indication for intervention for patients with severe aortic stenosis (AS) with discordant echocardiographic parameters. We investigated the agreement in flow-gradient classification by stroke volume (SV) measurement at the left ventricular outflow tract (LVOT) and at the left ventricle.

Methods

Data were used from a prospective cohort study and patients with severe AS (aortic valve area index ≤0.6 cm2/m2) with preserved ejection fraction (>50%) were selected. SV was determined by an echocardiographic core laboratory at the LVOT and by subtracting the 2-dimensional left ventricle end-systolic from the end-diastolic volume (volumetric). Patients were stratified into 4 groups based on SV index (35 mL/m2) and mean gradient (40 mm Hg). The group composition was compared and the agreement between the SV measurements was investigated using regression, correlation, and limits of agreement. In addition, a systematic LVOT diameter overestimation of 1 mm was simulated to study flow-gradient reclassification.

Results

Of 1118 patients, 699 were eligible. The group composition changed considerably as agreement on flow state occurred in only 50% of the measurements. LVOT SV was on average 15.1 mL (95% limits of agreement -24.9:55.1 mL) greater than volumetric SV. When a systematic 1-mm LVOT diameter overestimation was introduced, the low-flow groups halved.

Conclusions

There was poor agreement in the flow-gradient classification of severe AS as a result of large differences between LVOT and volumetric SV. Furthermore, this classification was sensitive to small measurement errors. These results stress that parameters beyond the flow-gradient classification should be considered to ensure accurate recommendations for intervention.

Three-Dimensional Echocardiography Assessment of Right Ventricular Volumes and Function: Technological Perspective and Clinical Application

Right ventricular (RV) function has important prognostic value in a variety of cardiovascular diseases. Due to complex anatomy and mode of contractility, conventional two-dimensional echocardiography does not provide sufficient and accurate RV function assessment. Currently, three-dimensional echocardiography (3DE) allows for an excellent and reproducible assessment of RV function owing to overcoming these limitations of traditional echocardiography. This review focused on 3DE and discussed the following points: (i) acquisition of RV dataset for 3DE images, (ii) reliability, feasibility, and reproducibility of RV volumes and function measured by 3DE with different modalities, (iii) the clinical application of 3DE for RV function quantification.

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.

The bicuspid aortic valve: Is it an immunological disease process?

Bicuspid aortic valves (BAVs) are the most common congenital cardiac condition and are characterized by a structural abnormality whereby the aortic valve is composed of two leaflets instead of being trileaflet. It is linked to an increased risk for a variety of complications of the aorta, many with an immunological pathogenesis. The aim of this study is to review and analyze the literature regarding immunological processes involving BAVs, associated common pathologies, and their incidence in the population. This study will also examine current trends in surgical and therapeutic approaches to treatment and discuss the future direction of BAV treatment.

MR Imaging of Thoracic Aortic Disease

A number of congenital defects and acquired disease processes affect the thoracic aorta, and traditionally, computed tomography (CT) has been the mainstay of imaging, especially in evaluation of the acute aorta. However, recent advances in magnetic resonance (MR) imaging such as electrocardiographically (ECG) triggered breath-hold sequences and ultrafast 3-dimensional MR angiography (MRA) are bringing MR imaging to the forefront of imaging of the thoracic aorta. By providing high-resolution morphological imaging and sophisticated vascular flow analysis for functional data, this modality can provide a comprehensive, reproducible evaluation of the thoracic aorta. In this review, we discuss the role of MR imaging in the evaluation of thoracic aorta pathology along with pertinent examples of aortic abnormalities.

Echocardiographic 3D-guided 2D planimetry in quantifying left-sided valvular heart disease

Echocardiographic 3D-guided 2D planimetry can improve the accuracy of valvular disease assessment. Acquisition of 3D pyramidal dataset allows subsequent multiplanar reconstruction with accurate orthogonal plane alignment to obtain the correct borders of an anatomic orifice or flow area. Studies examining the 3D-guided 2D planimetry approach in left-sided valvular heart disease were identified and reviewed. The strongest evidence exists for estimating mitral valve area in patients with rheumatic mitral valve stenosis and vena contracta area in patients with mitral regurgitation (both primary and secondary). 3D-guided approach showed excellent feasibility and reproducibility in most studies, as well as time efficiency and good correlation with reference and comparator methods. Therefore, 3D-guided 2D planimetry can be used as an important clinical tool in quantifying left-sided valvular heart disease, especially mitral valve disorders.

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.

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.

Multimodality imaging in heart valve disease

In patients with heart valve disease, echocardiography is the mainstay for diagnosis, assessment and serial surveillance. However, other modalities, notably cardiac MRI and CT, are used if echocardiographic imaging is suboptimal but can also give complementary information to improve assessment of the valve lesion and cardiac compensation to aid the timing of surgery and determine risk. This statement discusses the way these imaging techniques are currently integrated to improve care beyond what is possible with echocardiography alone.

Advanced echocardiographic techniques

Echocardiography has advanced significantly since its first clinical use. The move towards more accurate imaging and quantification has driven this advancement. In this review, we will briefly focus on three distinct but important recent advances, three‐dimensional (3D) echocardiography, contrast echocardiography and myocardial tissue imaging. The basic principles of these techniques will be discussed as well as current and future clinical applications.

Real time 3D echocardiography (RT3D) for assessment of ventricular and vascular function in hypertensive and heart failure patients

Background

Cardiac and systemic hemodynamics have been historically in the domain of invasive cardiology, but recent advances in real-time 3-Dimensional echocardiography (RT3D echo) provide a reliable measurement of ventricular volumes, allowing to measure a set of hemodynamic parameters previously difficult or impossible to obtain with standard 2D echo.

Aim

To assess the feasibility of a comprehensive hemodynamic study with RT-3D echo.

Methods

We enrolled 136 patients referred for routine echocardiography: 44 normal (N), 57 hypertensive (HYP), and 35 systolic heart failure patients (HF). All patients underwent standard 2D echo examination followed by RT3D echo examination, including measurement of left ventricular (LV) end-diastolic and end-systolic volumes and derived assessment of LV elastance (an index of LV contractility), arterial elastance (characterizing the distal impedance of the arterial system downstream of the aortic valve); ventricular-arterial coupling (a central determinant of net cardiovascular performance); systemic vascular resistances. Blood pressure was derived from cuff sphygmomanometer and heart rate from ECG.

Results

A complete 2D echo was performed in all 136 patients. 3D echo examination was obtained in 130 patients (feasibility = 95 %). Standard 2D echo examination was completed in 14.8 ± 2.2 min. Acquisition of 3D images required an average time of 5 ± 0.9 min (range 3.5-7.5 min) and image analysis was completed in 10.1 ± 2.8 min (range 6–12 min) per patient. Compared to N and HYP, HF patients showed reduced LV elastance (1.7 ± 1.5 mmHg mL^-1 m^-2, p <0.001 vs N = 3.8 ± 1.3 and HYP = 3.8 ± 1.3) and ventricular-arterial coupling (0.6 ± 0.5, p < 0.01 vs N = 1.4 ± 0.4 and HYP = 1.2 ± 0.4). Systemic vascular resistances were highest in HYP (2736 ± 720, p < .01 vs N = 1980 ± 432 and vs HF = 1855 ± 636 dyne*s/cm⁵). The LV elastance was related to EF (r = 0.73, p < 0.01) and arterial pressure was moderately related to vascular elastance (r = 0.54, p < 0.01). The ventricular-arterial coupling was unrelated to systemic vascular resistances (r = −0.04, p NS).

Conclusion

RT-3D echo allows a non invasive, comprehensive assessment of cardiac and systemic hemodynamics, offering insight access to key variables – such as increased systemic vascular resistances in hypertensives and reduced ventricular-arterial coupling in heart failure patients.

Comparison of Invasive and Noninvasive Assessment of Aortic Stenosis Severity in the Elderly

Background—

Aortic valve area (AVA) in aortic stenosis (AS) can be assessed noninvasively or invasively, typically with similar results. These techniques have not been validated in elderly patients, where common assumptions make them most prone to error. Accurate assessment of AVA is crucial to determine which patients are appropriate candidates for aortic valve replacement.

Methods and Results—

Fifty elderly patients (mean 86 years, 46% female) referred for cardiac catheterization to evaluate AS also underwent transthoracic echocardiography within 24 hours. To minimize assumptions all patients had 3-dimensional echocardiography (Echo-3D), and at catheterization using directly measured oxygen consumption (Cath-mVo 2 ) and thermodilution cardiac output (Cath-TD). Correlation between Cath-mVo 2 and Echo-3D AVA was poor ( r =0.41). Cath-TD AVA had a moderate correlation with Echo-3D AVA ( r =0.59). Cath-mVo 2 (AVA=0.69 cm 2 ) and Cath-TD (AVA=0.66 cm 2 ) underestimated AVA compared with Echo-3D (AVA=0.76 cm 2; P =0.08 for comparison with Cath-mVo 2 ; P =0.001 for Cath-TD). Compared with Echo-3D, the sensitivity and specificity for determining critical disease (AVA <0.8 cm 2 ) were 81% and 42% for Cath-mVo 2 , and 97% and 53% for Cath-TD. The only independent predictor of the difference between noninvasive and invasive AVA was stroke volume index ( P <0.01). Resistance, a less flow-dependent measure, showed a stronger correlation between Echo-3D and Cath-mVo 2 ( r =0.69), and Echo-3D and Cath-TD ( r =0.77).

Conclusions—

Standard techniques of AVA assessment for AS show poor correlation in elderly patients, with frequent misclassification of critical AS. Less flow-dependent measures, such as resistance, should be considered to ensure that only appropriate patients are treated with aortic valve replacement.

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.

Bicuspid aortic valve: spectrum of imaging findings at cardiac MDCT and cardiovascular MRI

OBJECTIVE

Cardiac MDCT and cardiovascular MRI have become widely used for the evaluation of cardiovascular disease, including aortic valve disease. The purpose of this article is to present the cardiac MDCT and cardiovascular MRI findings of bicuspid aortic valve, its various complications, and other congenital cardiovascular malformations.

CONCLUSION

Radiologists should be aware of the clinical significance and the varied appearance of bicuspid aortic valve at cardiac MDCT and cardiovascular MRI.

3D color-Doppler echocardiography and chronic aortic regurgitation: a novel approach for severity assessment

BACKGROUND

3D echocardiography provides a complete evaluation of the aortic valve and adjacent structures and it improves the assessment of this cardiac region. Three-dimensional color-Doppler echocardiography (3DCDE) evaluation might improve the measurements of the functional regurgitant orifice in patients with Chronic Aortic Regurgitation (CAR).

OBJECTIVES

Our aim was to compare the accuracy of current echo-Doppler methods and 3DCDE for the assessment of CAR severity. The reference method used in this work was the CAR severity determined by means of cardiac magnetic resonance (CMR) METHODS: Thirty-two consecutive patients with an established diagnosis of CAR recruited in our institution comprised our study group. CAR severity was determined by conventional Echo-Doppler methods and by 3DCDE and their results were compared with those obtained by means of CMR.

RESULTS

Mean age was 63.0 ± 13.5 years. Twenty-two patients (68.8%) were men. Compared with the traditional echo-Doppler methods, 3DCDE evaluation had the best linear association with CMR results (3D vena contracta cross sectional area method: r = 0.88; r square = 0.77; p < 0.001. 3D vena contracta cross sectional area/left ventricular outflow tract cross sectional area method: r = 0.87; r square = 0.75; p < 0.001). The ROC analysis showed an excellent area under curve for detection of severe CAR (3D vena contracta cross sectional area method = 0.97; 3D vena contracta cross sectional area/left ventricular outflow tract cross sectional area method = 0.98). Inter- and intra-observer variability for the 3DCDE evaluation was good (ICC = 0.89 and ICC = 0.91 for inter and intra observer variability respectively).

CONCLUSIONS

3DCDE is an accurate and highly reproducible diagnostic tool for estimating CAR severity. Compared with the traditional echo-Doppler methods, 3DCDE has the best agreement with the CMR determined CAR severity. Thus, 3DCDE is a diagnostic method that may improve the therapeutic management of patients with CAR.

Cardiac magnetic resonance imaging is more diagnostic than 2-dimensional echocardiography in determining the presence of bicuspid aortic valve

OBJECTIVE

This study compares 2-dimensional, transthoracic echocardiography with cardiac magnetic resonance imaging in the preoperative identification of bicuspid aortic valve before aortic valve surgery.

METHODS

Of 1203 patients who underwent an aortic valve operation, 218 had both preoperative transthoracic echocardiography and cardiac magnetic resonance imaging. Patients in the study group were aged 56 years and had an ejection fraction of 56%, 76% were male, and 29% had associated coronary artery disease. The results of transthoracic echocardiography and cardiac magnetic resonance imaging were classified as bicuspid aortic valve, trileaflet aortic valve, or nondiagnostic. Of the 218 patients, 123 (56%) had bicuspid aortic valve as determined at the time of surgery and 116 (53%) had an ascending aortic aneurysm.

RESULTS

Of the 123 patients with bicuspid aortic valve confirmed at surgery, by transthoracic echocardiography 76 (62%) were identified preoperatively with bicuspid aortic valve, 12 (10%) were misidentified with trileaflet aortic valve, and 35 (28%) were nondiagnostic for valve morphology. In the same patients with bicuspid aortic valve, by cardiac magnetic resonance imaging 115 (93%) were identified with bicuspid aortic valve, 5 (4%) were misidentified with trileaflet aortic valve, and 3 (2%) were nondiagnostic. The difference between transthoracic echocardiography and cardiac magnetic resonance imaging to determine the presence of bicuspid aortic valve was statistically significant (P<.001). In the entire cohort of patients, transthoracic echocardiography was diagnostic for valve morphology in 155 patients (71%) compared with cardiac magnetic resonance imaging, which was diagnostic in 212 patients (97%) (P<.001).

CONCLUSIONS

Cardiac magnetic resonance imaging is more diagnostic than transthoracic echocardiography in determining the presence of bicuspid aortic valve. A significant factor is the rate of nondiagnostic transthoracic echocardiography for aortic valve morphology. Cardiac magnetic resonance imaging can be performed as a complementary test when transthoracic echocardiography is nondiagnostic for aortic valve morphology.

Real time triplane echocardiography in the assessment of the functional area of prosthetic aortic valves: reliability and feasibility

PURPOSE

Our study is aimed at evaluating the feasibility and reliability of a simple method for the measurement of the functional area of prosthetic aortic valves (EOA). Three-dimensional echocardiography has proven accurate for left ventricular volume, stroke volume, and aortic valve area measurement. We studied the feasibility and reliability of real time simultaneous triplane echocardiography (RT3P) for assessing the EOA with a fast formula based on the principle of continuity equation, in which we replaced Doppler-derived stroke volume (SV) with SV directly measured with RT3P.

METHODS AND RESULTS

EOA of prosthetic aortic valves were measured in 23 consecutive patients requiring periodical follow up. EOA was calculated using Doppler continuity equation (DCE) and the RT3P method by replacing Doppler-derived SV with SV measured with real time triplane echocardiography. We compared functional areas obtained with the two methods with the prosthetic area indicated in the manufacturer's specifications and with the mean transprosthetic gradient. Both methods had a good correlation with the area indicated by the manufacturer. RT3P revealed an inverse correlation between functional area and mean gradient that was better than DCE (P = 0.0359). Inter- and intraobserver variability was not different between the two methods. Execution time was significantly shorter for RT3P.

CONCLUSIONS

RT3P is a simple method that can be performed quite rapidly, and can complement the overall assessment of prosthetic valve function. Further studies can confirm our technique.

Valve anatomy and function with transthoracic three-dimensional echocardiography: advantages and limitations of instantaneous full-volume color Doppler imaging

Three-dimensional echocardiography (3DE) is becoming part of everyday clinical practice worldwide. However, 3DE requires adequate electrocardiographic and respiratory gating and it complements instead of replacing bidimensional echocardiography (2D). The instantaneous full-volume echocardiography technique is trying to overcome some of these limitations and to present an effective alternative to 2D echocardiography. In this article we aim to review the contribution of 3DE to our knowledge of anatomic and functional valvular anatomy and the potential advantages of instantaneous full-volume color Doppler echocardiography.

Pitfalls of anatomical aortic valve area measurements using two-dimensional transoesophageal echocardiography and the potential of three-dimensional transoesophageal echocardiography

AIMS

The aims of this study were to (i) investigate aortic annulus dynamics using two-dimensional (2D) speckle tracking echocardiography, (ii) determine optimal 2D short-axis view for the calculation of planimetric aortic valve area (AVA), and (iii) compare 2D planimetric AVA extracted from volumetric three-dimensional data sets using real-time 3DTEE (three-dimensional transoesophageal echocardiography) with standard 2DTEE planimetry.

METHODS AND RESULTS

We studied 60 patients with aortic stenosis (AS) and 10 control subjects. AVA was calculated by standard 2DTEE planimetry method, volumetric 3DTEE method, and continuity equation (CE) from transthoracic echocardiography. In addition, aortic annular motion was studied using 2D speckle tracking. Aortic annulus moves cranially during early systole and subsequently moves caudally during the remainder of systole and isovolumic relaxation. Annulus again moved in the cranial direction during diastole in both groups. Although AVA correlated well between 2DTEE and 3DTEE methods (r = 0.95), 2DTEE showed a significantly larger AVA compared with 3DTEE method (1.26 +/- 0.39 vs. 1.10 +/- 0.39 cm(2), P < 0.001). In patients in whom aortic cusps were visible in 2DTEE short-axis images during systole only (n = 45), AVA using 2DTEE was still larger than that measured with 3DTEE. However, the bias in AVA was significantly lower compared with the remaining 15 patients (-0.13 +/- 0.11 vs. -0.26 +/- 0.12 cm(2), P < 0.005). Although both methods showed moderate correlation with AVA by CE (r = 0.78, 0.75), mean differences were significantly smaller by 3DTEE than 2DTEE (-0.01 +/- 0.25 vs. -0.17 +/- 0.27 cm(2), P < 0.001).

CONCLUSION

Aortic annular motion affects the calculation of AVA using 2DTEE. Three-dimensional transoesophageal echocardiography has a potential for more accurate determination of anatomical AVA.

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

OBJECTIVE

We sought to evaluate the relationship among left ventricular outflow tract diameter (LVOTd), gender, and body surface area (BSA) and to evaluate the usefulness of size-adjusted LVOTd reference values in patients with aortic stenosis (AS). AS grading is based on the echocardiographic calculation of the aortic valve area (AVA) and requires LVOTd measurements, one main potential source of error. Transesophageal echocardiography (TEE) is reputed to be more accurate than transthoracic echocardiography (TTE), but validation studies are rare. A safeguard for LVOTd measurements is thus desirable.

METHODS

Since January 2006, 3 subsets of patients have been prospectively and concurrently enrolled: 1) TEE group: In 120 patients with and without AS, we prospectively measured LVOTd during both TTE and TEE. 2) Validation set: In 382 patients without aortic valve or ascending aorta diseases, we evaluated the relationship among LVOTd, gender, and BSA. 3) Testing set: In 173 patients with AS, we compared the AVA obtained using measured LVOTd (AVA(MEAS)) and calculated LVOTd derived from a regression determined in the validation set (AVA(CALC)).

RESULTS

TTE did not differ from and correlated well with TEE measurements overall (23 +/- 2 mm vs 23 +/- 2 mm, P = .26; r = 0.95, P < .0001) and in patients with AS (N = 43) (24 +/- 2 mm vs 24 +/- 3 mm, P = .15; r = 0.92, P < .0001). LVOTd was linearly correlated to BSA independently of gender (LVOTd = 5.7 * BSA+12.1; r = 0.55, P < .0001). In the testing set, AVA(CALC) did not differ from and correlated well with AVA(MEAS) (1.20 +/- 0.42 cm2 vs 1.23 +/- 0.40 cm2; P = .08; r = 0.89; P < .0001).

CONCLUSION

TTE and TEE measurements of the LVOTd provided similar results. LVOTd was significantly associated to BSA and LVOTd, derived from a linear regression linked to BSA independently of gender, provided an acceptable approximation of the AVA. Thus, although accurate measurement of LVOTd is a crucial part of the echocardiographic evaluation of AS severity, the present equation may be used as a safeguard when this measurement is difficult or not possible with TTE.

[Update on cardiac imaging techniques: echocardiography, cardiac magnetic resonance, and multidetector computed tomography]

This article contains a review of the most important publications on cardiac imaging that have appeared during 2008. During the year, we assisted with the clinical implementation of three-dimensional real-time transesophageal echocardiography, with the use of echocardiography for selecting patients for and monitoring those who underwent percutaneous aortic valve replacement (the majority of centers performing the technique were still in the learning phase), and with the emergence in the clinic of techniques for studying myocardial deformation. Also reviewed are the most significant developments in the application of echocardiography to coronary heart disease and cardiac resynchronization therapy and in 2 other techniques whose use is constantly increasing: cardiac magnetic resonance and multidetector cardiac computed tomography. The review ends with a description of the current state of the art in contrast echocardiography, with particular emphasis on safety in the context of recommendations made by the US Food and Drug Administration at the end of 2007.