Xiao Zhou

Recommendations for the imaging assessment of prosthetic heart valves: a report from the European Association of Cardiovascular Imaging endorsed by the Chinese Society of Echocardiography, the Inter-American Society of Echocardiography, and the Brazilian Department of Cardiovascular Imaging †

Prosthetic heart valve (PHV) dysfunction is rare but potentially life-threatening. Although often challenging, establishing the exact cause of PHV dysfunction is essential to determine the appropriate treatment strategy. In clinical practice, a comprehensive approach that integrates several parameters of valve morphology and function assessed with 2D/3D transthoracic and transoesophageal echocardiography is a key to appropriately detect and quantitate PHV dysfunction. Cinefluoroscopy, multidetector computed tomography, cardiac magnetic resonance imaging, and to a lesser extent, nuclear imaging are complementary tools for the diagnosis and management of PHV complications. The present document provides recommendations for the use of multimodality imaging in the assessment of PHVs.

Quantitative Prediction of Paravalvular Leak in Transcatheter Aortic Valve Replacement Based on Tissue-Mimicking 3D Printing

OBJECTIVESnThis study aimed to develop a procedure simulation platform for inxa0vitro transcatheter aortic valve replacement (TAVR) using patient-specific 3-dimensional (3D) printed tissue-mimicking phantoms. We investigated the feasibility of using these 3D printed phantoms to quantitatively predict the occurrence, severity, and location of any degree of post-TAVR paravalvular leaks (PVL).nnnBACKGROUNDnWe have previously shown that metamaterial 3D printing technique can be used to create patient-specific phantoms that mimic the mechanical properties of biological tissue. This may have applications inxa0proceduralxa0planning for cardiovascular interventions.nnnMETHODSnThis retrospective study looked at 18 patients who underwent TAVR. Patient-specific aortic root phantoms were created using the tissue-mimicking 3D printing technique using pre-TAVR computed tomography. The CoreValve (self-expanding valve) prostheses were deployed in the phantoms to simulate the TAVR procedure, from which post-TAVR aortic root strain was quantified inxa0vitro. A novel index, the annular bulge index, was measured to assess the post-TAVR annular strain unevenness in the phantoms. We tested the comparative predictive value of the bulge index and other known predictors of post-TAVR PVL.nnnRESULTSnThe maximum annular bulge index was significantly different among patient subgroups that had no PVL, trace-to-mild PVL, and moderate-to-severe PVL (pxa0= 0.001). Compared with other known PVL predictors, bulge index was the only significant predictor of moderate-severe PVL (area under the curvexa0= 95%; pxa0< 0.0001). Also, in 12 patients with post-TAVR PVL, the annular bulge index predicted the major PVL location in 9 patients (accuracyxa0= 75%).nnnCONCLUSIONSnIn this proof-of-concept study, we have demonstrated the feasibility of using 3D printed tissue-mimicking phantoms to quantitatively assess the post-TAVR aortic root strain inxa0vitro. A novel indicator of the post-TAVR annular strainxa0unevenness, the annular bulge index, outperformed the other established variables and achieved a high level of accuracy in predicting post-TAVR PVL, in terms of its occurrence, severity, and location.

Comparison of conventional echocardiographic parameters of RV systolic function with cardiac magnetic resonance imaging

Background Cardiac magnetic resonance (CMR) imaging is the reference standard to assess right ventricular (RV) volumes and ejection fraction. However, 2-D echocardiography is commonly used for routine assessment of the RV and a number of quantitative measures have been recommended to evaluate systolic function. Measurement of right ventricular ejection fraction (RVEF), which is a key predictor of outcomes in a range of right heart diseases, is not recommended because of the limitations of 2-D imaging of the RV. Instead Fractional Area Change (FAC %)by 2-D Echocardiography and tricuspid annular plane systolic excursion (TAPSE) are recommended as surrogate measures of RV global systolic function. The aim of our study is to compare the conventional parameters of RV systolic function currently used by 2-D echocardiography with RVEF and stroke volume (SV) measured by CMR.

Feasibility of Automated Three-Dimensional Rotational Mechanics by Real-Time Volume Transthoracic Echocardiography: Preliminary Accuracy and Reproducibility Data Compared with Cardiovascular Magnetic Resonance

BACKGROUNDnThree-dimensional (3D) speckle-tracking echocardiography (STE) for myocardial strain imaging may be superior to two-dimensional STE, especially with respect to rotational mechanics. Automated strain measurements from nonstitched 3D STE may improve work flow and clinical utility. The aim of this study was to test the feasibility of model-based 3D STE for the automated measurement of voxel circumferential strain (Ecc) and myocardial rotation.nnnMETHODSnThirty-five individuals (12 healthy volunteers, 12 patients with dilated cardiomyopathy, and 11 patients with hypertensive left ventricular [LV] hypertrophy) were prospectively studied. The latter two groups did not have significant coronary artery disease on coronary arteriography. Tagged cardiovascular magnetic resonance (CMR) and feature-tracking CMR were used as reference standards. Regional (apex and mid left ventricle) and slice (within a region) Ecc and rotation were measured by real-time volume transthoracic echocardiography (nonstitched) using an automated algorithm.nnnRESULTSnCompared with both CMR techniques, apical and mid-LV Ecc (concordance correlation coefficients [CCCs], 0.84-0.95 and 0.48-0.68) and rotation (CCCs, 0.70-0.95 and 0.42-0.68) showed excellent, good, and moderate agreement, respectively. At the LV base, rotation showed poor agreement with CMR methods (CCC, 0.04-0.21), consistent with previous descriptions, but calculated LV twist showed moderate to good correlation with CMR techniques (CCC, 0.61-0.84). However, the 95% CI for measurements between techniques was wide, emphasizing the challenges in comparing voxel deformation by 3D echocardiography with CMR, compounded by differences in approaches to measuring deformation, and matching regional and slice measurements between techniques. Reproducibility (n = 10, including test-retest variability) of automated 3D strain and rotation measurements was good to excellent (coefficient of variation < 10%) and was comparable with that of CMR methods (coefficient of variation < 10%) in the same patients.nnnCONCLUSIONSnThe data from this study show that automated measurements of voxel rotational mechanics by real-time volume transthoracic echocardiography is feasible and comparable with tagged CMR and feature-tracking CMR strain measurements, albeit with wide limits of agreement, emphasizing the differences between the modalities. Furthermore, this automated 3D speckle-tracking echocardiographic approach shows excellent reproducibility, including test-retest variability, comparable with that of the CMR methods.

Intervendor Consistency and Accuracy of Left Ventricular Volume Measurements Using Three-Dimensional Echocardiography

BACKGROUNDnIntervendor consistency of left ventricular (LV) volume measurements using three-dimensional transthoracic echocardiography (3DTTE) has never been reported. Accordingly, we designed a prospective study to (1) compare head-to-head the accuracy of three three-dimensional echocardiography (3DE) systems in measuring LV volumes and ejection fraction (EF) against cardiac magnetic resonance (CMR); (2) assess the intervendor variability of LV volumes and EF; and (3) compare the accuracy of fully automated versus semiautomated (i.e., manually corrected) methods of LV endocardial delineation against CMR.nnnMETHODSnWe studied 92 patients (64% males, 52xa0years [95% CI, 20-83]) with a wide range of end-diastolic volumes (from 87 to 446xa0mL) and EFs (from 16% to 77%) using three different 3DE platforms (iE33; Vivid E9; Acuson SC2000) during the same echo study. CMR was performed within 3xa0±xa05xa0hours from the 3DE study in 35 patients.nnnRESULTSnLV volumes provided by the three 3DE systems correlated with CMR volumes: end-diastolic volume (iE33: R2xa0=xa00.93; E9: R2xa0=xa00.94; SC2000: R2xa0=xa00.94), end-systolic volume (iE33: R2xa0=xa00.93; E9: R2xa0=xa00.95; SC2000: R2xa0=xa00.94), and EF (iE33: R2xa0=xa00.79; E9: R2xa0=xa00.80; SC2000: R2xa0=xa00.77). In the 92 patients studied, LV volumes and EFs measured with the three systems were similar. Use of fully automated endocardial border detection algorithms significantly underestimated LV volumes, and the degree of underestimation was higher with larger LV volumes.nnnCONCLUSIONSnLV volumes and EFs measured with the three 3DE systems are consistent. Fully automated algorithms underestimated LV volumes. Our findings may help in the clinical interpretation of LV parameters obtained using different 3DE systems and encourage the clinical use of 3DTTE.

3-D PRINTING OF BIOLOGICAL TISSUE-MIMICKING AORTIC ROOT USING A NOVEL META-MATERIAL TECHNIQUE: POTENTIAL CLINICAL APPLICATIONS

Mimicking the dynamic mechanical properties of the human aorta in 3D printed models is challenging because of the inherent difference between mechanical behaviors of polymeric materials and human tissues (Fig. A). We sought to print the aortic root using materials which achieved the strain-

Quantitative Three-Dimensional Color Flow Echocardiography of Chronic Mitral Regurgitation: New Methods, New Perspectives, New Challenges

Echocardiography is the imaging modality of choice to quantify chronic mitral regurgitation (MR), and the current American College of Cardiology/American Heart Association and European Society of Cardiology guidelines on valve disease emphasize the central role of quantitative parameters obtained from color flow Doppler (CFD) imaging in grading the severity of chronic MR. However, given the well-described limitations of quantitative CFD imaging, an integrated approach (which includes data from spectral Doppler), and measurements of left ventricular (LV) size and function, are also included in the recommendations for quantitating MR. In the real world, trivial, mild, and severe MR are obvious, and quantitative measures often confirm eyeball assessments of severity. But the classification of ‘‘moderate’’ MR poses uncertainty with respect to visual assessment, and there is considerable variability among interpreters. In fact, the use of descriptors in everyday practice such as ‘‘moderate to severe MR’’ and ‘‘solid moderate MR’’ reflect this uncertainty. It is in this situation in which quantitative methods have the most impact, either confirming moderate MR or upgrading or downgrading the degree of MR, similar to the nature of the benefit seen with stress imaging testing for chest pain in patients with intermediate pretest risk for coronary artery disease. Another more contemporary indication for routine quantification of MR is in the assessment of residual MR after transcatheter or surgical valve repair, when eyeball assessment is often extremely difficult if not impossible. Even if qualitative assessment was possible, accurate quantification is necessary in these circumstances for appropriate clinical decision making.

4D Flow Imaging in Aortic Disease

The flow hemodynamics in the aorta plays a critical role in the formation and development of aortic disease. 4D flow imaging using phase-contrast magnetic resonance (4D PC-MRI) has been developed and performed in both research and clinical care to study the blood flow in the heart and the great vessels. Compared to 2D flow imaging, 4D PC-MRI allows retrospective visualization and quantification of the time-varying 3D blood flow pattern in the 3D volume of the aorta, and provides more comprehensive visual and quantitative tools to study the complex relationship between flow hemodynamics and aortic pathophysiology in the development of aortic disease. In this chapter, we will describe the image acquisition technique, the image pre-processing method, the data visualization technique, and the quantitative hemodynamic markers of the 4D flow PC-MRI in the aorta. This chapter will also give an overview of the potential clinical applications of the flow visualization and the flow quantifications derived from 4D flow imaging for aortic disease.

Functional Anatomy and Dynamics of the Aortic Root

The anatomy of the aortic root is a sophisticated structure uniquely designed to optimize its function. Each component of the aortic root (Fig. 3.1) is deliberately assembled to allow the stroke volume to be ejected as a laminar flow with minimal resistance and minimal tissue wear and tear [1]. This organized action of the components of the aortic root is critical to the efficiency of the left ventricular pump, normal coronary blood flow, and the distinctive flow pattern in the aorta [2–6]. Thus, an understanding of the functional anatomy of the aortic root is essential to understand the clinical consequences of the disruption of this complex structure. This understanding also is key to the surgical repair techniques aimed to restore this sophisticated anatomy in various diseases of the aortic root. The following section will first describe the structure of the aortic root and in the second part describe the coordinated functioning of this complex yet intuitively efficient structure.

Comparison of noninvasive three dimensional delayed enhancement MRI of left atrial scar with invasive voltage map by using robust 4D point-to-point registration in patients with atrial fibrillation

Background Left Atrial scar imaging using delayed enhancement MRI (DE-MRI) has been proposed as a promising tool to guide ablation strategies in patients with atrial fibrillation (AF). Studies have shown that the scar areas detected by DE-MRI correlate with the low voltage areas on the co-registered electroanatomic voltage map based on surface matching. However, such matching methods did not consider the misalignment of the scar areas: a point-to-point comparison between DE-MRI and voltage map remains problematic. In this study, we proposed a robust 4D (3D of geometry and 1D of scar degree) registration algorithm for the point-to-point comparison of DE-MRI and voltage map. Based on the registered images, we hypothesized that by utilizing complex image information extracted from DE-MRI, we were able to predict the low voltage areas in the coregistered voltage maps.