Comparison of two-dimensional and real-time three-dimensional transesophageal echocardiography in the assessment of aortic valve area

Usefulness of Three-Dimensional Transthoracic Echocardiographic Planimetry in a 4-Month-Old Infant with Comorbid Aortic Stenosis and Coarctation of the Aorta Complicated with Low Left Ventricular Ejection Fraction

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Comorbid valvular AS, CoA, and LV dysfunction can complicate the order of interventions.

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Continuity equation cannot be used to assess AS severity in the setting of decreased LVEF.

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3D-TTE planimetry can evaluate AS severity in infants with good acoustic windows.

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.

Grading of aortic stenosis severity: a head-to-head comparison between cardiac magnetic resonance imaging and echocardiography

AIM

To prospectively evaluate the accuracy of cardiac magnetic resonance (cMR) imaging for the assessment of aortic valve effective orifice area (EOA) by continuity equation and anatomical aortic valve area (AVA) by direct planimetry, as compared with transthoracic (TTE) and transesophageal (TEE) two-dimensional (2D) echocardiography, respectively.

METHODS AND RESULTS

A total of 31 patients (21 men, 10 women, mean age 69 ± 10 years) with moderate-to-severe aortic stenosis (AS) diagnosed by TTE and scheduled for elective aortic valve replacement, underwent both cMR and TEE. AVA by cMR was obtained from balanced steady-state free-precession cine-images. EOA was computed from phase-contrast MR flow analysis. AVA at cMR (0.93 ± 0.42 cm²) was highly correlated with TEE-derived planimetry (0.92 ± 0.32 cm²) (concordance correlation coefficient, CCC = 0.85). By excluding 11 patients with extensively thickened and heavily calcified cusps, the CCC increased to 0.93. EOA at cMR (0.86 ± 0.30 cm²) showed a strong correlation with TTE-derived EOA (0.78 ± 0.25 cm²) (CCC = 0.82).

CONCLUSIONS

cMR imaging is an accurate alternative for the grading of AS severity. Its use may be recommended especially in patients with poor transthoracic acoustic windows and/or in case of discordance between 2D echocardiographic parameters.

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.

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.

Intraoperative three-dimensional transesophageal echocardiography for evaluating an unusual structure in the left ventricular outflow tract: a case report

Intraoperative three-dimensional (3D) transesophageal echocardiography (TEE) facilitates an understanding of the complex cardiac pathology that is not fully delineated in a two-dimensional (2D) echocardiographic evaluation, and it suggests earlier and more precise surgical planning and intraoperative decision making. In the present case, the intraoperative 2D-TEE midesophageal long-axis view indicated a significant narrowing of the left ventricular outflow tract (LVOT) area by a band-like structure that vertically traversed the middle of the LVOT and connected to the anterior mitral leaflet base and the interventricular septum. However, additional 3D-TEE images of the LVOT and their cropped and rendered 2D images showed that web-like tissue, which presumably had grown around the patch closure from a previous atrioventricular septal defect, was obstructing the LVOT partially.

[Application fields of intraoperative transesophageal 3D echocardiography]

Intraoperative transesophageal echocardiography (TEE) is an established diagnostic tool and has to be regarded as the standard of care for intraoperative monitoring and cardiac surgical decision-making. Furthermore, intraoperative TEE is also used for monitoring and assessment of hemodynamic changes and the detection of previously unknown pathologies. In the past few years 3D-TEE has extended the spectrum of 2D-TEE by allowing pathomorphological features to be more easily and intuitively linked to the anatomy of the heart and the great vessels. Thus, a comprehensive 2D-TEE examination is favorably complemented by focused 3D-TEE. Especially during mitral valve surgery, 3D-TEE has proven its superiority in the diagnosis of the underlying pathology as demonstrated by a large number of studies in this field. This review presents the available data about the role of intraoperative 3D-TEE echocardiography and introduces practical fields of application.

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.

Long-term follow-up of stentless prosthesis

BACKGROUND

Stentless prostheses have an interesting hemodynamic performance when compared to stented prostheses and are recommended in cases of small aortic annulus.

MATERIALS AND METHODS

From January 1996 to January 2004, 138 patients suffering from aortic disease, underwent aortic valve replacement. • Group A: 93 patients underwent stentless aortic valve implantation [stentless Biocor (Biocor Industria e Pesguisa Ltda, Belo Horizonte, Brazil) and stentless Sorin (Sorin Group, Saluggia, Italy)]. • Group B: 45 patients underwent stented aortic valve implantation (stented Biocor). Patients were assessed by clinical evaluation and echocardiography after a mean follow up of 124.5 ± 58.2 months.

RESULTS

There was a significant difference in terms of time of extracorporeal circulation and aortic cross clamp. The actuarial survival at 4, 8, 12, and 15 years is 77%, 50%, 21%, and 18%, respectively. Freedom from reoperation at 4, 8, 12, and 14 years was 92%, 83%, 73%, and 63%, respectively. Freedom from all events, death, and reoperation at 4, 8, 12, and 14 years was 70%, 39%, 13%, and 8%, respectively. There is no statistical difference among the two groups in terms of actuarial survival, freedom from reoperation, and freedom from re-hospitalization for prosthesis-related causes.

DISCUSSION

There was a significantly higher incidence of pacemaker implantation in Group A and the causes are not known. The rate of freedom from reoperation is high in both groups for the patients who remained alive. There was no statistical difference about prosthesis dysfunction between the two groups. The higher incidence of death in Group A cannot be explained by causes related to the prosthesis because there is no difference in terms of causes of death. Rates of reoperation did not differ between the two groups.

CONCLUSIONS

The results obtained with stentless prostheses are encouraging even in long-term follow-up.

Non-invasive and invasive evaluation of aortic valve area in 100 patients with severe aortic valve stenosis: comparison of cardiac computed tomography with ECHO (transesophageal/transthoracic) and catheter examination

BACKGROUND

Current guidelines place emphasis on the determination of aortic valve area (AVA) for defining an appropriate treatment strategy. Invasive and non-invasive modalities are used to perform planimetric [transesophageal echocardiography (TEE) and cardiac multidetector computed tomography (MDCT)] and calculated [catheter examination (CE), transthoracic echocardiography (TTE)] AVA measurements.

PURPOSE AND METHODS

We investigated 100 patients admitted to evaluate the AVA using cardiac MDCT (CT), TEE/TTE as well as invasive CE.

RESULTS

In all 100 patients we calculated a mean AVA of 0.79±0.29cm(2) (female 50/100, 0.70±0.19cm(2), male 0.9±0.21cm(2)) determined by all investigated examinations (mean±SEM). AVA measurements determined by CT were significantly greater (0.86±0.25cm(2)) than those determined by CE: 0.75±0.18cm(2), p=0.01. Echocardiographically determined AVA was comparable to CE (statistically not significant). Similar results were seen in all patients regardless of gender, presence of atrial fibrillation, and heart rate. We calculated a mean AVA for each patient and evaluated the variance of the AVA determined through investigated specific examinations as the bias. Overall, we found for CT 0.13±0.1cm(2), CE 0.13±0.11cm(2), TEE 0.16±0.09cm(2), and for TTE 0.16±0.08cm(2) a specific statistical non-significant variance. On subgroups: sinus rhythm, atrial fibrillation, females, males or combination, we found no further significant relevance for the specific variance.

CONCLUSION

Our data suggest the feasibility of cardiac MDCT to evaluate the correct AVA regardless of rhythm, heart rate, and sex. The planimetric concept to determine the AVA with CT displaces the "gold-standard" CE with respect to elucidating the potencies for complications, i.e. cerebral stroke. Regardless of CT's accessing of AVA measurement the TTE examination should remain the primary method of screening for aortic valve pathologies.

Prognostic value of global left ventricular strain for conservatively treated patients with symptomatic aortic stenosis

AIMS

Impaired left ventricular (LV) strain is associated with an increased risk of cardiac events in asymptomatic severe aortic stenosis (AS). We aimed to evaluate the prognostic value of global LV strain in conservatively treated patients with symptomatic AS.

METHODS AND RESULTS

This cohort study retrospectively reviewed symptomatic AS patients who were treated conservatively or surgically between July 2007 and April 2010. We measured their global longitudinal strain (GLS) and global circumferential strain (GCS). Clinical events were defined as readmission for heart failure or all-cause death for 2 years. GLS and GCS could predict a worse outcome in the conservatively treated group at cut-offs of =-16.5% (77% sensitivity and 67% specificity) and =-22.2% (92% sensitivity and 83% specificity), respectively. By univariate Cox regression analysis, age, logistic EuroSCORE, aortic valve area, GLS, and GCS were significant predictors. When adjusted for age, logistic EuroSCORE, and aortic valve area, impaired GLS and GCS were independently associated with a higher risk of clinical events.

CONCLUSION

In conservatively treated patients with symptomatic AS, impaired GLS and GCS were associated with an increased risk of cardiac events during a 2-year follow-up. Global LV strain may help to define a higher risk subset; therefore, a larger and prospective observation study would be necessary.