Alex Pui-Wai Lee

Quantitative Analysis of Mitral Valve Morphology in Mitral Valve Prolapse With Real-Time 3-Dimensional Echocardiography Importance of Annular Saddle Shape in the Pathogenesis of Mitral Regurgitation

Background— Few data exist on the relation of the 3-dimensional morphology of mitral valve and degree of mitral regurgitation (MR) in mitral valve prolapse. Methods and Results— Real-time 3-dimensional transesophageal echocardiography of the mitral valve was acquired in 112 subjects, including 36 patients with mitral valve prolapse and significant MR (≥3+; MR+ group), 32 patients with mitral valve prolapse but no or mild MR (⩽2+; MR− group), 12 patients with significant MR resulting from nonprolapse pathologies (nonprolapse group), and 32 control subjects. The 3-dimensional geometry of mitral valve apparatus was measured with dedicated quantification software. Compared with the normal and MR− groups, the MR+ group had more dilated mitral annulus (P<0.0001), a reduced annular height to commissural width ratio (AHCWR) (P<0.0001) indicating flattening of annular saddle shape, redundant leaflet surfaces (P<0.0001), greater leaflet billow volume (P<0.0001) and billow height (P<0.0001), longer lengths from papillary muscles to coaptation (P<0.0001), and more frequent chordal rupture (P<0.0001). Prevalence of chordal rupture increased progressively with annulus flattening (7% versus 24% versus 42% for AHCWR >20%, 15%–20%, and <15%, respectively; P=0.004). Leaflet billow volume increased exponentially with decreasing AHCWR in patients without chordal rupture (r2=0.66, P<0.0001). MR severity correlated strongly with leaflet billow volume (r2=0.74, P<0.0001) and inversely with AHCWR (r2=0.44, P<0.0001). In contrast, annulus dilatation but not flattening occurred in nonprolapse MR patients. An AHCWR <15% (odds ratio=7.1; P=0.0004) was strongly associated with significant MR in mitral valve prolapse. Conclusion— Flattening of the annular saddle shape is associated with progressive leaflet billowing and increased frequencies of chordal rupture and may be important in the pathogenesis of MR in mitral valve prolapse.Background— Few data exist on the relation of the 3-dimensional morphology of mitral valve and degree of mitral regurgitation (MR) in mitral valve prolapse. Methods and Results— Real-time 3-dimensional transesophageal echocardiography of the mitral valve was acquired in 112 subjects, including 36 patients with mitral valve prolapse and significant MR (≥3+; MR+ group), 32 patients with mitral valve prolapse but no or mild MR (≤2+; MR− group), 12 patients with significant MR resulting from nonprolapse pathologies (nonprolapse group), and 32 control subjects. The 3-dimensional geometry of mitral valve apparatus was measured with dedicated quantification software. Compared with the normal and MR− groups, the MR+ group had more dilated mitral annulus ( P 20%, 15%–20%, and <15%, respectively; P =0.004). Leaflet billow volume increased exponentially with decreasing AHCWR in patients without chordal rupture ( r 2=0.66, P <0.0001). MR severity correlated strongly with leaflet billow volume ( r 2=0.74, P <0.0001) and inversely with AHCWR ( r 2=0.44, P <0.0001). In contrast, annulus dilatation but not flattening occurred in nonprolapse MR patients. An AHCWR <15% (odds ratio=7.1; P =0.0004) was strongly associated with significant MR in mitral valve prolapse. Conclusion— Flattening of the annular saddle shape is associated with progressive leaflet billowing and increased frequencies of chordal rupture and may be important in the pathogenesis of MR in mitral valve prolapse. # Clinical Perspective {#article-title-34}

Quantification of left ventricular regional myocardial function using two-dimensional speckle tracking echocardiography in healthy volunteers — A multi-center study

BACKGROUND Although two-dimensional speckle tracking (2DST) has been validated in animal and early clinical studies for quantitative evaluation of myocardial motion and contractility, there are only limited measurements in large healthy population to be used as reference data, which severely restricts its clinical application. This study aimed at determining the age-specific normal values of left ventricular (LV) longitudinal, circumferential and radial strain in healthy adults. METHODS We studied 228 healthy subjects (109 males, mean age 44 ± 15 years, range 18-78 years). Their LV longitudinal, circumferential and radial strains were measured by 2DST at basal, middle and apical levels of parasternal short-axis and apical 2-, 4- and 3-chamber views. The effects of age, gender and echocardiographic machines (52 patients had measurements obtained by both GE and Philips machines) on these parameters were also evaluated. RESULTS The longitudinal and circumferential strains were -20.4 ± 3.4% and -22.9 ± 3.1%, respectively with higher values being observed at basal than apical segments. On the contrary, the radial strain which ranged 42.6 ± 12.9% decreased towards apical segments. The longitudinal strain declined, the circumferential strain rose and the radial strain remained similar during aging. Adult females had slightly higher circumferential and longitudinal strains than males (23 ± 3% vs -22 ± 3%, -21 ± 3% vs -20 ± 3% respectively; both p<0.01). Strains measured by the 2 different echo machines had good correlations but Phillips-assessed strains (longitudinal and circumferential) were 10% higher than GE measurements. Inter- and intra-observer variabilities were acceptable. CONCLUSIONS Strain measurements by 2DST echocardiography varies with age, gender and echocardiographic vendors in healthy adults. These findings are important to differentiate between health and disease and to assess the severity of disease.

Importance of dynamic dyssynchrony in the occurrence of hypertensive heart failure with normal ejection fraction

AIMS The impact of haemodynamic stress on left ventricular (LV) dyssynchrony in heart failure with normal ejection fraction (HFNEF) remains unknown. We sought to evaluate the relationship and predictive value of dynamic changes of LV dyssynchrony on hypertensive HFNEF. METHODS AND RESULTS A total of 131 subjects including 47 hypertensive HFNEF patients, 34 hypertensive patients with left ventricular hypertrophy (LVH) without HFNEF, and 50 normal controls were studied by dobutamine stress echocardiography with tissue Doppler imaging. Systolic and diastolic dyssynchrony were assessed using the LV six-basal-six-mid-segment model and cut-off values were derived from normal controls. The mean basal segments longitudinal systolic (mean Sm) and early diastolic (mean Em) velocities were measured. In normal controls, systolic and diastolic dyssynchrony did not develop during stress. The prevalence of resting systolic (36.2% vs. 38.2%, P = 0.85) and diastolic (34.0% vs. 29.4%, P = 0.66) dyssynchrony was similar in HFNEF and LVH groups. During stress, the prevalence of systolic and diastolic dyssynchrony increased dramatically to 85.1% and 87.2%, respectively, in HFNEF group, but only 52.9% and 58.8% in LVH group (P < 0.005). In HFNEF group, stress-induced increase in mean Sm was significantly blunted (2.8 ± 2.0 vs. 4.2 ± 2.4 cm/s, P = 0.004), and the increase was abolished for mean Em (-0.3 ± 2.5 vs. 2.4 ± 3.4 cm/s, P < 0.001). On multivariate analysis, stress-induced changes in mean Em (OR = 0.69, P = 0.004) and mean Sm (OR = 0.56, P = 0.004), and diastolic (OR = 4.6, P = 0.005) and systolic dyssynchrony during stress (OR = 4.3, P = 0.038) were independent determinants for occurrence of HFNEF. CONCLUSION Dynamic dyssynchrony during stress and impaired myocardial longitudinal function reserve are characteristics of HFNEF.

Left atrial regional phasic strain, strain rate and velocity by speckle-tracking echocardiography: Normal values and effects of aging in a large group of normal subjects

BACKGROUND Two-dimensional (2D) speckle tracking echocardiography (STE) is a new tool for evaluation of LA function. The aims of this study are to establish the normal range of LA function measured by 2DSTE in different age groups and to evaluate the relations between the parameters of 2DSTE and Doppler echocardiography in evaluating LA and LV diastolic function in healthy adults. METHODS A total of 121 healthy volunteers (62 males, aged 47±15) were studied. The LA STE curves were obtained using R-wave onset of the electrocardiogram as a reference point. The LA strain during systolic, early and late diastole (εs, εa and εe = εr - εa); strain rate (SRs, SR, SRe and SRa); velocity (Vs, Ve and Va) were analyzed by commercialized software (EchoPAC). The differences between these parameters were analyzed in different age groups (≤35, 36-55 and ≥55 years) in both genders and compared with the corresponding Doppler echocardiographic indices. RESULTS Global LA εs, εe, and εa were 46.8±7.7, 27.3±6.4 and 19.6±4.2%; SRs, SRe, and SRa were 2.4±0.5, -2.4±0.7 and -2.8±0.6 1/s; Vs, Ve and Va were -5.3±0.9, 5.8±1.2 and 5.2±1.1cm/s respectively. The global LA 2DSTE parameters significantly correlated with Doppler echocardiographic indices which represented LA or LV diastolic function. Moreover, the STE LA parameters correlated significantly with age but not gender. CONCLUSIONS This study provides the normal range of LA strain, strain rate and velocity in 3 age groups, which are closely correlated with LA and LV function. The detailed assessment of LA phasic mechanics by 2DSTE may prove to be an important tool for future clinical studies.

Feasibility of single-beat full-volume capture real-time three-dimensional echocardiography for quantification of right ventricular volume: Validation by cardiac magnetic resonance imaging

BACKGROUND The lack of an accurate noninvasive method for assessing right ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our study was to test the feasibility of single-beat full-volume capture with real-time three-dimensional echo (3DE) imaging system for the evaluation of RV volumes and function validated by cardiac magnetic resonance imaging (CMRI). METHODS Sixty-one subjects (16 normal subjects, 20 patients with hypertension, 16 patients with pulmonary heart disease and 9 patients with coronary heart disease) were studied. RV volume and function assessments using 3DE were compared with manual tracing with CMRI as the reference method. RESULTS Fifty-nine of 61 patients (96.7%; 36 male, mean age, 62 ± 15 years) had adequate three-dimensional echocardiographic data sets for analysis. The mean RV end diastolic volume (EDV) was 105 ± 38 ml, end-systolic volume (ESV) was 60 ± 30 and RV ejection fraction (EF) was 44 ± 11% by CMRI; and EDV 103 ± 38 ml, ESV 60 ± 28 ml and RV EF 41 ± 13% by 3DE. The correlations and agreements between measurements estimated by two methods were acceptable. CONCLUSION RV volumes and function can be analyzed with 3DE software in most of subjects with or without heart diseases, which is able to be estimated with single-beat full-volume capture with real-time 3DE compared with CMRI.

Role of real time three-dimensional transesophageal echocardiography in guidance of interventional procedures in cardiology

Real-time three-dimensional transesophageal echocardiography (RT-3D TEE) employs a dedicated novel matrix-array technology and allows live three-dimensional (3D) presentation of cardiac structures, circumventing most of the time-consuming acquisition and offline data processing associated with reconstructive 3D methods. It is particularly useful in guiding non-coronary cardiac interventions, defining location, morphology and possible pathology of cardiac structure of interest, its anatomical relation to neighbouring landmarks while providing improved spatial resolution and, in addition, allowing online monitoring of the procedure. These advantages over two-dimensional (2D) transesophageal echocardiography (TEE), intracardiac echocardiography and fluoroscopy may enhance decision-making, reduce fluoroscopy time and increase procedural safety and efficacy in short and long-term follow-up. It is foreseeable that RT-3D TEE will have the most clinical utility in the following 5 years. This review summarises the current development and clinical applications of RT-3D TEE for the guidance of percutaneous cardiac interventions, as well as surgical planning and subsequent follow-up of valvular repair and replacement. 3D TEE was developed approximately 25 years ago with the aim of providing additional anatomical detail and improved spatial relationships, not previously seen with transthoracic two-dimensional echocardiography. Until the introduction of the matrix TEE probe 2 years ago, 3D TEE was performed with a multiplane probe using a rotational approach for sequential data acquisition, gated to ECG and respiration. From a transesophageal fixed acoustic window, 2D images were collected at small angular increments, post-processed offline and converted into a Cartesian coordinate system to obtain conical volume datasets. From these data, any desired cut-plane could be derived and structures of interest rendered. Unfortunately, this methodology was limited by the need for multiple image sampling resulting in lengthy data acquisition times and frequent radial artifacts. As a consequence, this methodology has not been routinely embraced in clinical practice and was predominantly used for research purposes. To overcome these limitations and introduce …

Increased Rho kinase activity in congestive heart failure

Rho kinases (ROCKs) are the best characterized effectors of the small G‐protein RhoA, and play a role in enhanced vasoconstriction in animal models of congestive heart failure (CHF). This study examined if ROCK activity is increased in CHF and how it is associated with the outcome in CHF.

Improved coronary artery blood flow following the correction of systolic dyssynchrony with cardiac resynchronization therapy

BACKGROUND Coronary blood flow (CBF) is improved by cardiac resynchronization therapy (CRT) and impaired by right ventricular apical (RVA) pacing in patients with heart failure. However, the underlying mechanism remains unclear. METHODS Twenty-nine non-ischemic heart failure patients who responded to CRT underwent transthoracic echocardiography examination including both left anterior descending (LAD) CBF and tissue Doppler imaging in 3 pacing modes: intrinsic conduction, RVA pacing and biventricular (BiV) pacing. LAD velocity-temporal integral (LAD-VTI) and duration were measured. Systolic dyssynchrony was assessed with the standard deviation of a 12-left ventricular segmental model (Ts-SD). RESULTS BiV pacing improved while RVA pacing reduced CBF compared to intrinsic conduction (all p<0.05). Both Ts-SD and ventricular septal velocity deteriorated during RVA pacing but improved during BiV pacing (all p<0.05). When systolic dyssynchrony was induced, lower LAD-VTI (9.5 ± 3.4 versus 12.7 ± 5.1cm, p=0.001) and shorter LAD diastolic duration (483 ± 92 versus 542 ± 106 ms, p=0.010) were detected than synchronous status. Systolic dyssynchrony was inversely related to septal velocity (r=-0.41), p<0.001 and LAD-VTI (r=-0.30, p=0.007), with the latter found to be moderately correlated to septal velocity (r=0.30, p=0.007). CONCLUSION Regional LAD flow was improved in patients subjected to BiV but worsened in those treated with RVA pacing in non-ischemic heart failure CRT responders. Systolic dyssynchrony was more commonly observed in patients subjected to RVA pacing. Reduction of septal velocity with dyssynchrony may directly lead to reduced LAD flow. Improvement of septal velocity by CRT and hence LAD flow may be an important mechanism in determining the response to CRT.

Electrophysiological Mechanisms of Gastrointestinal Arrhythmogenesis: Lessons from the Heart.

Disruptions in the orderly activation and recovery of electrical excitation traveling through the heart and the gastrointestinal (GI) tract can lead to arrhythmogenesis. For example, cardiac arrhythmias predispose to thromboembolic events resulting in cerebrovascular accidents and myocardial infarction, and to sudden cardiac death. By contrast, arrhythmias in the GI tract are usually not life-threatening and much less well characterized. However, they have been implicated in the pathogenesis of a number of GI motility disorders, including gastroparesis, dyspepsia, irritable bowel syndrome, mesenteric ischaemia, Hirschsprung disease, slow transit constipation, all of which are associated with significant morbidity. Both cardiac and gastrointestinal arrhythmias can broadly be divided into non-reentrant and reentrant activity. The aim of this paper is to compare and contrast the mechanisms underlying arrhythmogenesis in both systems to provide insight into the pathogenesis of GI motility disorders and potential molecular targets for future therapy.

Three-dimensional speckle strain echocardiography is more accurate and efficient than 2D strain in the evaluation of left ventricular function

BACKGROUND Two-dimensional speckle tracking echocardiography (2DSTE) has been used widely in research, but rarely in clinical practice because data acquisition and analysis are time-consuming. By reducing the acquisition and analysis time, 3-dimensional STE may improve clinical impact. We investigated the feasibility of 3DSTE myocardial deformation, with comparison to 2DSTE. METHODS Transthoracic 3DSTE and 2DSTE were performed in 230 adults (138 men, 51 ± 14 years, and 142 hypertension, 10 heart failure and 78 normotensive subjects). The variables of LV deformation were analyzed using EchoPAC software. RESULTS The 3D LV longitudinal (LS) analysis was feasible in 84.9% of the study subjects, which was lower than the 2D analysis (97.2%). The success rates for circumferential strain (CS) and radial strain (RS) were similar between the 2D and 3D techniques. All magnitude of strains measured by 2DSTE and 3DSTE were significantly correlated. The magnitude of 3D LS and CS was lower, but the 3D RS is higher than that of 2DSTE (-18.5 ± 2.8 vs. -21.2 ± 3.5; 20.8 ± 4.1 vs. 21.7; and 50.0 ± 11.2 vs. 37.7 ± 12.6, respectively). Strains measured by 3DSTE exhibited stronger correlation with LV ejection fraction (EF) than that by 2DSTE. In inter- and intra-observer reproducibility for 3D LS, CS, RS and AS were acceptable. The mean time of analysis for LV volume, EF and strains was 116s by 3DSTE, which was significantly shorter than that by 2DSTE (5 min, P<0.0001). CONCLUSIONS Three-dimensional STE is feasible and reproducible in the estimation of LV function, requires substantially less time than 2DSTE and is a more feasible technique for LV function assessment in clinical practice.