Ben Ren

Segmentation of multiple heart cavities in 3-D transesophageal ultrasound images

Three-dimensional transesophageal echocardiography (TEE) is an excellent modality for real-time visualization of the heart and monitoring of interventions. To improve the usability of 3-D TEE for intervention monitoring and catheter guidance, automated segmentation is desired. However, 3-D TEE segmentation is still a challenging task due to the complex anatomy with multiple cavities, the limited TEE field of view, and typical ultrasound artifacts. We propose to segment all cavities within the TEE view with a multi-cavity active shape model (ASM) in conjunction with a tissue/blood classification based on a gamma mixture model (GMM). 3-D TEE image data of twenty patients were acquired with a Philips X7-2t matrix TEE probe. Tissue probability maps were estimated by a two-class (blood/tissue) GMM. A statistical shape model containing the left ventricle, right ventricle, left atrium, right atrium, and aorta was derived from computed tomography angiography (CTA) segmentations by principal component analysis. ASMs of the whole heart and individual cavities were generated and consecutively fitted to tissue probability maps. First, an average whole-heart model was aligned with the 3-D TEE based on three manually indicated anatomical landmarks. Second, pose and shape of the whole-heart ASM were fitted by a weighted update scheme excluding parts outside of the image sector. Third, pose and shape of ASM for individual heart cavities were initialized by the previous whole heart ASM and updated in a regularized manner to fit the tissue probability maps. The ASM segmentations were validated against manual outlines by two observers and CTA derived segmentations.

Contributions of Simultaneous Multiplane Echocardiographic Imaging in Daily Clinical Practice

Two-dimensional (2D) transthoracic echocardiography (TTE) is one of the most frequently used techniques for diagnosis, management, and follow-up of patients with any suspected or known cardiovascular disease. It is based on multiple single cardiac planes taken from standard positions on the chest wall. With the development of the matrix transducer, three-dimensional echocardiography (3D) can now be performed in the routine laboratory reducing the number of cross sections needed for the information required. However, there are several challenges for the use of 3D echocardiography in daily clinical practice. First, there is the need for a separate 3D transducer, which has a lower temporal resolution compared to the standard 2D transducer. Second, the acquisition time of 3D images is time consuming and most often requires offline analysis. Third, 3D echocardiography is a relatively new technique, which requires extra training and it has a learning curve. Recently, a new generation 2D/3D matrix transducer has become available, overcoming some of these drawbacks and even introducing a new image modality called “simultaneous multiplane imaging” (SMPI). This new modality permits the use of a full electronic rotation of 360° of the 2D image (I-Rotate) and a simultaneously adjustable biplane 2D image (xPlane). In this article, we will discuss the potential contributions of SMPI in daily clinical practice.

Relation between calcium burden, echocardiographic stent frame eccentricity and paravalvular leakage after corevalve transcatheter aortic valve implantation

Aims Paravalvular aortic leakage (PVL) after transcatheter aortic valve implantation (TAVI) is a complication with potentially severe consequences. The relation between native aortic root calcium burden, stent frame eccentricity and PVL was not studied before. Methods and results Two-hundred-and-twenty-three consecutive patients with severe aortic stenosis who underwent TAVI with a Medtronic CoreValve System© and who had available pre-discharge transthoracic echocardiography were studied. Echocardiographic stent inflow frame eccentricity was defined as major–minor diameter in a short-axis view >2 mm. PVL was scored according to the updated Valve Academic Research Consortium (VARC-2) recommendations. In a subgroup of 162 (73%) patients, the calcium Agatston score was available. Stent frame eccentricity was seen in 77 (35%) of patients. The correlation between the Agatston score and stent frame eccentricity was significant (&rgr; = 0.241, P = 0.003). Paravalvular leakage was absent in 91 cases (41%), mild in 67 (30%), moderate in 51 (23%), and severe in 14 (6%) cases. The correlation between stent frame eccentricity and PVL severity was significant (&rgr; = 0.525, P < 0.0001). There was a relation between particular eccentric stent frame shapes and the site of PVL. Conclusion Calcification of the aortic annulus is associated with a subsequent eccentric shape of the CoreValve prosthesis. This eccentric shape results in more PVL, with the localization of PVL related to the shape of stent frame eccentricity.

Characterization of atrial septal defect by simultaneous multiplane two-dimensional echocardiography

AIMS The aim of this study was to assess the value of two-dimensional (2D) transthoracic simultaneous multiplane imaging (SMPI) in the evaluation of suitability for percutaneous atrial septal secundum defect (ASD) closure compared with the golden standard 2D transoesophageal echocardiography (TEE). METHODS AND RESULTS Twenty-nine patients with an ASD underwent both SMPI and TEE. Ten patients (34%) were male (age 41 ± 18 years, range 20-74). SMPI assessment of ASD size and rims included xPlane and I-rotate modes. Rims were defined as suitable for ASD percutaneous closure using a cut-off value of 5 mm. There were no significant differences between SMPI in xPlane mode and TEE regarding the sizes of the anterior-posterior dimension (13.7 ± 4.5 vs. 14.5 ± 5.2 mm) and superior-inferior dimension (13.5 ± 3.9 vs. 14.1 ± 5.0 mm, respectively). Agreement for the aortic, atrioventricular, inferior, right upper pulmonary vein, and superior rims was 100, 100, 100, 96, and 96%, respectively. CONCLUSION The SMPI technique can reliably assess the dimensions and rim size of a secundum ASD for pre-interventional selection when compared with TEE and has thus the potential to replace TEE.

Comparison of valve performance of the mechanically expanding Lotus and the balloon-expanded SAPIEN3 transcatheter heart valves: an observational study with independent core laboratory analysis.

Aims The Lotus and SAPIEN3 are second-generation transcatheter heart valves, which are designed to minimize paravalvular aortic regurgitation (PAR) after transcatheter aortic valve replacement (TAVR). We sought to compare both devices for valve performance and with emphasis on PAR by independent core laboratory analysis. Methods and results A total of 162 (79 Lotus and 83 SAPIEN3) consecutive patients (51% female, 80 ± 8 years, Logistic EuroSCORE 14.8 ± 9.4%) who underwent TAVR because of aortic stenosis were included. Patients with aortic valve-in-valve treatment were excluded. Pre-discharge echocardiograms were analysed by an independent core laboratory using the Valve Academic Research Consortium 2 criteria. There were no differences in baseline and procedural characteristics, except for a larger aortic annulus and sizing indices in SAPIEN3-treated patients and frequency of post-dilatation (0% in Lotus and 13.1% in SAPIEN3). Both valves have similar mean residual gradient, indexed effective orifice area and Doppler velocity index when adjusted to valve size. The frequency of mild (13.9% vs. 31.3%) and at least moderate (1.3% vs. 3.6%) PAR was less after Lotus than after SAPIEN3 implantation (P = 0.02). Multi-slice computed tomography-based annulus and left ventricular outflow tract diameters, calcification and percentage of oversizing were not different between those with or without mild or more PAR. On multivariate analysis, the use of Lotus valve was associated with less (odds ratio OR, 0.41, P = 0.03) occurrence of PAR. Conclusion Overall, haemodynamic performance was comparable between the Lotus and SAPIEN3 valves. Lotus valve required less oversizing and was associated with less PAR than SAPIEN3.

The role of experience in echocardiographic identification of location and extent of mitral valve prolapse with 2D and 3D echocardiography

Contradiction exists on the incremental value of two-dimensional (2D) and 3D transoesophageal echocardiography (TOE) over 2D transthoracic echocardiography (TTE) for the detection of mitral valve (MV) prolapse in readers with different echocardiographic experience. Twenty patients and five healthy persons were retrospectively identified who had undergone 2D-TTE, 2D-TOE and 3D-TOE. Fifteen (75 %) patients had surgical evidence of prolapse of the posterior MV leaflet and five patients (25 %) had a dilated MV annulus without prolapse. Three reader groups with different echocardiographic expertise (novice, trainees, cardiologists) scored thus in total 675 posterior scallops. Overall there was an improvement in agreement and Kappa values from novice to trainees to cardiologists. Diagnostic accuracies of 2D-TOE were higher than those of 2D-TTE mainly in novice readers. The incremental value of 3D-TOE over 2D-TOE was mainly seen in specificities. Time to diagnosis was dramatically reduced from 2D to 3D-TEE in all reader groups (all P < 0.001). 3D-TOE also improved the agreement (+12 to +16 %) and Kappa values (+0.14 to +0.21) in all reader groups for the exact description of P2 prolapse. Differences between readers with variable experience in determining the precise localization and extent of the prolapsing posterior MV scallops exist in particular in 2D-TTE analysis. 3D-TOE analysis was extremely fast compared to the 2D analysis methods and showed the best diagnostic accuracy (mainly driven by specificity) with identification of P1 and P3 prolapse still improving from novice to trainees to cardiologists and provided optimal description of P2 prolapse extent.

Prediction of paravalvular leakage after transcatheter aortic valve implantation

Significant paravalvular leakage (PVL) after transcatheter aortic valve implantation (TAVI) is related to patient mortality. Predicting the development of PVL has focused on computed tomography (CT) derived variables but literature targeting CoreValve devices is limited, controversial, and did not make use of standardized echocardiographic methods. The study included 164 consecutive patients with severe aortic stenosis that underwent TAVI with a Medtronic CoreValve system©, with available pre-TAVI CT and pre-discharge transthoracic echocardiography. The predictive value for significant PVL of the CT-derived Agatston score, aortic annulus size and eccentricity, and “cover index” was assessed, according to both echocardiographic Valve Academic Research Consortium (VARC) criteria and angiographic Sellers criteria. Univariate predictors for more than mild PVL were the maximal diameter of the aortic annulus size (for both angiographic and echocardiographic assessment of PVL), cover index (for echocardiographic assessment of PVL only), and Agatston score (for both angiographic and echocardiographic assessment of PVL). The aortic annulus eccentricity index was not predicting PVL. At multivariate analysis, Agatston score was the only independent predictor for both angiographic and echocardiographic assessment of PVL. Agatston score is the only independent predictor of PVL regardless of the used imaging technique for the definition of PVL.

Limitations and difficulties of echocardiographic short-axis assessment of paravalvular leakage after corevalve transcatheter aortic valve implantation

To make assessment of paravalvular aortic leakage (PVL) after transcatheter aortic valve implantation (TAVI) more uniform the second Valve Academic Research Consortium (VARC) recently updated the echocardiographic criteria for mild, moderate and severe PVL. In the VARC recommendation the assessment of the circumferential extent of PVL in the short-axis view is considered critical. In this paper we will discuss our observational data on the limitations and difficulties of this particular view, that may potentially result in overestimation or underestimation of PVL severity.

Accuracy of an automated transthoracic echocardiographic tool for 3D assessment of left heart chamber volumes

The feasibility and accuracy of an automated adaptive algorithm (Heart Model) for the quantification of left heart chamber volumes and left ventricular ejection fraction has been reported earlier. An improved version of the algorithm is available, and we aimed to test its accuracy compared with manual 3D echocardiography.

A granular approach to improve reproducibility of the echocardiographic assessment of paravalvular regurgitation after TAVI

Paravalvular leak (PVL) after transcatheter aortic valve implantation (TAVI) is challenging to quantitate. Transthoracic echocardiography (TTE) is the main tool used for the assessment of PVL but is modestly reproducible. We sought to develop a reproducible echocardiographic approach to assess PVL in the post-TAVI setting. Four observers independently analyzed eleven parameters of PVL severity in 50 pre-discharge TTE studies performed after TAVI. The parameters included color-Doppler parameters [jet circumferential extent (CE) and planimetered vena contracta area in the short-axis view and jet breadth and qualitative features in the long-axis views], continuous-wave Doppler parameters [jet velocity time integral (VTI) and pressure half time (PHT)], quantitative Doppler parameters (regurgitation volume and fraction and effective regurgitant orifice area), aortic diastolic flow reversal and valve stent eccentricity. Intraclass correlation coefficient (ICC) and coefficient of variation (CV) for numerical parameters and kappa coefficient (κ) for categorical parameters were calculated for inter- and intra-observer comparisons. Inter-observer ICC was highest and CV lowest for CE (0.88 and 0.36), jet origin breadth (0.82 and 0.39), jet qualitative features in long-axis views (0.87 and 0.26), jet VTI (0.87 and 0.04) and PHT (0.73 and 0.10). Similar results were found in intra-observer comparisons. A 2-step granular approach combining the most reproducible parameters was used to grade PVL by the four observers. Inter-observer agreement was achieved in 86 % of cases (κ = 0.79). Combining color Doppler and continuous wave Doppler parameters in a granular algorithm yields excellent reproducibility of PVL assessment by TTE.