LV Mechanics in Mitral and Aortic Valve Diseases: Value of Functional Assessment Beyond Ejection Fraction

The assessment of myocardial function in the context of valvular heart disease remains highly challenging. The myocardium deforms simultaneously in 3 dimensions, and global left ventricular (LV) function parameters such as volume and ejection fraction may remain compensated despite the changes in myocardial deformation properties. Current guidelines recommend valve replacement/repair in the presence of symptoms or reduced LV ejection fraction, but the resolution of symptoms or recovery of LV function post-surgery may not be reliably predicted. A wealth of evidence currently suggests that LV dysfunction is frequently subclinical despite normal ejection fraction. It may precede the onset of symptoms and portend a poor outcome due to progressive myocardial remodeling and dysfunction during the post-operative period. The advent of novel tissue-tracking echocardiography techniques has unleashed new opportunities for the clinical identification of early abnormalities in LV function. This review gathers and summarizes current evidence regarding the use of these techniques to assess myocardial deformation in patients with valvular heart disease.     

In vivo X-ray cine-tomography for tracking morphological dynamics

Scientific cinematography using ultrafast optical imaging is a common tool to study motion. In opaque organisms or structures, X-ray radiography captures sequences of 2D projections to visualize morphological dynamics, but for many applications full four-dimensional (4D) spatiotemporal information is highly desirable. We introduce in vivo X-ray cine-tomography as a 4D imaging technique developed to study real-time dynamics in small living organisms with micrometer spatial resolution and subsecond time resolution. The method enables insights into the physiology of small animals by tracking the 4D morphological dynamics of minute anatomical features as demonstrated in this work by the analysis of fast-moving screw-and-nut–type weevil hip joints. The presented method can be applied to a broad range of biological specimens and biotechnological processes.The best method to study morphological changes of anatomic features and physiological processes is to observe their dynamics in 4D, that is, in real time and in 3D space. To achieve this we have developed in vivo X-ray cine-tomography to gain access to morphological dynamics with unrivaled 4D spatiotemporal resolution. This opens the way to a wide range of hitherto inaccessible, systematic investigations of small animals and biological internal processes such as breathing, circulation, digestion (1), reproduction, and locomotion (2).At the micrometer resolution range, state-of-the-art optical imaging techniques can achieve high magnifications to visualize tissues and even individual cells for 4D studies. These methods however are confined to transparent or fluorescent objects, or are limited either by low penetration depth <1 mm or poor time resolution (3). For optically opaque living organisms X-ray imaging methods are highly appropriate due to the penetrating ability of the radiation. Modern synchrotron radiation facilities provide brilliant and partially coherent radiation suitable for high-resolution volume imaging methods such as X-ray computed microtomography (SR-µCT). For static specimens SR-µCT has proven to be a powerful tool to study small animal morphology in 3D (4–6). The benefits of various physical contrast mechanisms, high spatial resolution, and short measuring times, as well as enormous sample throughput compared with laboratory X-ray setups, have led to its widespread use in life sciences.Real-time in vivo X-ray imaging with micrometer spatial resolution was realized so far by recording time sequences of 2D projection radiographs of different organisms (1, 6, 7), providing time information about functional dynamics but losing any information about the third spatial dimension.Recently, 4D in vivo X-ray experiments have been performed to study cell migration in frog embryos (8, 9) using tomographic sequences of a few seconds exposure time per tomogram interrupted by longer nonexposure time slots. In this way the authors followed relatively slow dynamics and morphological changes during embryonic development with 2-µm resolution over total time intervals of several hours. The fastest 4D time series yet reported were realized with a temporal resolution of 0.5 s and spatial resolution of 25 µm (10), applied to a living caterpillar used as test specimen for imaging, but without any analysis of dynamics.In this paper, we demonstrate the quantitative 4D investigation of morphological dynamics by in vivo X-ray 4D cine-tomography, introduced here as the combination of ultrafast SR-µCT and motion analysis procedures. Using this approach allows us to investigate previously inaccessible 3D morphological dynamics in small animals, presently with feature sizes in the micrometer range and with temporal resolution down to a few tens of milliseconds. In the past, ultrafast in vivo imaging was hardly possible for such applications, due to the strongly competing requirements for simultaneous high contrast, high signal-to-noise ratio (SNR), and concurrent low radiation dose, as well as the need for simultaneous high spatial resolution and maximum temporal resolution.In the following we describe how in vivo X-ray 4D cine-tomography meets the above challenges by optimizing image contrast, SNR, and spatial and temporal resolution in the ultrafast SR-µCT system and by establishing a dedicated data analysis pipeline, all within a unified framework (Fig. S1). We demonstrate the potential of the technique by investigating morphological dynamics in fast-moving weevils, focusing here on the exoskeletal joints.     

Discovering knowledge of hemodialysis (HD) quality using granularity-based rough set theory

This study collected the real HD-data from area scale hospital database with 72 attributes and 18,113 records. The study proposes a novel procedure to assess the patient's HD-quality, including five facets: (1) Delete the unrelated attributes and missing values. (2) Employ expert granularity to cut decision-attributed Kt/V (where K is the dialyzer clearance coefficient of urea nitrogen, t is the time for dialysis and V is the urea nitrogen volume of distribution in the body). (3) Use information-gain to select features, to reduce the total number of attributes to 17. (4) Utilize multiple regression to test the degree of co-linearity and select features, the dimension of dataset is reduced to 8 attributes and 2737 records. (5) Finally, the rules of HD-quality and accuracy performance are generated by granular rough set theory. In performance comparison, the decision tree (DT-C4.5), the Naïve Bayes (NB) probabilistic model and Artificial Neural Networks-Multilayer Perceptrons (ANN-MLP) are employed to compare with the proposed procedure in accuracy. The results can assist doctors to reduce the time of diagnosis and to achieve dose of fitness-based dialysis for the patients.     

Three-dimensional speckle-tracking echocardiography: methodological aspects and clinical potential

Speckle-tracking echocardiography (STE) is an advanced echocardiographic technique that allows a novel approach to the assessment of cardiac physiology through the study of myocardial mechanics. In its three-dimensional (3D) modality, it overcomes the drawbacks inherent to other echocardiographic techniques, namely two-dimensional echocardiography and tissue Doppler imaging. Several research studies and software improvements have led 3D-STE to become a promising tool for accurate evaluation of global and regional cardiac function. This article addresses the image acquisition, analytical methods, and parameters of myocardial mechanics that could be derived from 3D-STE. This systematic guidance may help to establish its usefulness in the global and regional evaluation of cardiac function, and to facilitate its clinical application.     

Early detection of left ventricular systolic dysfunction using two-dimensional speckle tracking strain evaluation in healthy subjects after acute alcohol intoxication

Objectives: We evaluated the ability of two-dimensional speckle tracking strain echocardiography to detect left ventricular (LV) systolic dysfunction as compared with LV ejection fraction (EF) in healthy subjects following acute alcohol intoxication. Methods and Results: In total, 25 healthy subjects were investigated using echocardiography 4-6 hours after the onset of alcohol intoxication at a regional festive gathering, and then compared to 23 healthy control subjects without alcohol consumption. Heart rate, blood pressure, blood alcohol level, LV volumes, EF, shortening fraction, E/A ratio, as well as global longitudinal strain (LS) were recorded. Mean blood alcohol level was 1.3 ± 0.3 g.L(-1) . Mean systolic blood pressure and heart rate were slightly increased in the alcohol group compared to controls (147.5 ± 21.8 mmHg vs 127.0 ± 9.9 mmHg, P = 0.003, and 79.7 ± 10.7 bpm vs 70.6 ± 7.6 bpm, P < 0.001, respectively). While there was no significant difference in terms of LVEF (62.9 ± 4.4% vs 64.8 ± 5.9%, P = 0.18) or shortening fraction (34.7 ± 5.9% vs 36.0 ± 4.3%, P = 0.54), global LS was significantly impaired (-17.8 ± 2.0% vs -21.2 ± 1.8%, P < 0.001). In addition, subjects who consumed alcohol had increased LV end-diastolic (108.3 ± 20.1 mL vs 95.5 ± 14.6 mL, P = 0.037) and end-systolic volumes (41.6 ± 11.4 mL vs 33.7 ± 6.9 mL, P = 0.024), along with depressed aortic time-velocity integral (19.9 ± 3.2 mL vs 21.9 ± 2.5 mL, P = 0.034). According to multivariate linear regression analyses, blood alcohol level was the only factor significantly associated with global LS (β=-3.6 ± 1.0, P = 0.005). Conclusion: Alcohol intoxication around festive days induces acute LV contraction abnormalities, which may be detected using global LS by speckle tracking at an earlier stage and more accurately than LVEF decreases.     

A novel motion tracking system for evaluation of functional rehabilitation of the upper limbs

Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the effec tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensorbased monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We devel oped a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensorbased motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual realitybased neurorehabili tation system.