BACKGROUND:This study aims to understand the age-related changes in vortex formation time (VFT) index in children, and thus, describe the ranges of VFT in different pediatric age groups with the ultimate goal of assessment of diastolic function. METHODS AND RESULTS:Transthoracic echocardiograms in healthy (n = 84) subjects from birth to 20 years were analyzed to compute VFT and diastolic performance. LV apical and short-axis views were used. Three separate measurements were performed, and the mean was used to derive VFT and other indices. Statistical comparisons were made amongst the groups, stratified by age. RESULTS:Vortex formation times in neonates (median 1.79, interquartile range 1.31-1.92) and infants (1.38, 1.07-1.72) were found to be significantly lower (P < .05) than the older age groups (1-5 years 2.47, 1.87-2.94, 5-10 years 2.18, 1.89-2.53, 10-20 years 2.34, 1.84-2.96). The changes in VFT correlate to the changes in diastolic function in children. CONCLUSION:Our results show that unlike adults, VFT changes along with the growth-related myocardial adaptations in children, and its range may be used to evaluate diastolic function. The present study is the first to test the significance of the trans-mitral VFT in children by comparing different age groups of healthy subjects.

The prevalence of aortic valve stenosis (AS) is increasing in the aging society. More recently, novel treatments and devices for AS, especially transcatheter aortic valve replacement (TAVR) have significantly changed the therapeutic approach to this disease. Research and development related to TAVR require testing these devices in the calcified heart valves that closely mimic a native calcific valve. However, no animal model of AS has yet been available. Alternatively, animals with normal aortic valve that are currently used for TAVR experiments do not closely replicate the aortic valve pathology required for proper testing of these devices. To solve this limitation, for the first time, we developed a novel polymeric valve whose leaflets possess calcium hydroxyapatite inclusions immersed in them. This study reports the characteristics and feasibility of these valves. Two types of the polymeric valve, i.e., moderate and severe calcified AS models were developed and tested by deploying a transcatheter valve in those and measuring the related hemodynamics. The valves were tested in a heart flow simulator, and were studied using echocardiography. Our results showed high echogenicity of the polymeric valve, that was correlated to the severity of the calcification. Aortic valve area of the polymeric valves was measured, and the severity of stenosis was defined according to the clinical guidelines. Accordingly, we showed that these novel polymeric valves closely mimic AS, and can be a desired cost-saving solution for testing the performance of the transcatheter aortic valve systems in vitro.

A major issue in translation of the artificial intelligence platforms for automatic segmentation of echocardiograms to clinics is their generalizability. The present study introduces and verifies a novel generalizable and efficient fully automatic multi-label segmentation method for four-chamber view echocardiograms based on deep fully convolutional networks (FCNs) and adversarial training. For the first time, we used generative adversarial networks for pixel classification training, a novel method in machine learning not currently used for cardiac imaging, to overcome the generalization problem. The method's performance was validated against manual segmentations as the ground-truth. Furthermore, to verify our method's generalizability in comparison with other existing techniques, we compared our method's performance with a state-of-the-art method on our dataset in addition to an independent dataset of 450 patients from the CAMUS (cardiac acquisitions for multi-structure ultrasound segmentation) challenge. On our test dataset, automatic segmentation of all four chambers achieved a dice metric of 92.1%, 86.3%, 89.6% and 91.4% for LV, RV, LA and RA, respectively. LV volumes' correlation between automatic and manual segmentation were 0.94 and 0.93 for end-diastolic volume and end-systolic volume, respectively. Excellent agreement with chambers' reference contours and significant improvement over previous FCN-based methods suggest that generative adversarial networks for pixel classification training can effectively design generalizable fully automatic FCN-based networks for four-chamber segmentation of echocardiograms even with limited number of training data.

Various forms of vortex formation in the cardiovascular system convey valuable information regarding the function of heart and great vessels. The vortex ring that forms during systole in the aortic sinus is the first that was recognized and the asymmetric transmitral vortex ring that forms in the left ventricle during diastole has been most commonly used for diagnosis and follow up of heart failure patients. Adverse vortex interaction in the heart can also occur due to valvular regurgitation and may have energetic consequences to the heart. Furthermore, vortices do exist in other chambers such as the right ventricle and may even arise in the great arteries and veins due to congenital heart disease. Here, we summarize diagnostic and prognostic significance of vortices and vortex imaging in the heart, their applications in clinical medicine, and discuss how these flow features can be used to assess functional status of the heart.

Paravalvular leak (PVL) is a complication of transcatheter aortic valve replacement. Despite its marked clinical impact, no previous study has reported how PVL affects the intraventricular fluid dynamics. This study aims to delineate vortex interaction between PVL and transmitral flow and the influence of PVL orifice location on intraventricular fluid dynamics using Echocardiographic Particle Image Velocimetry. Three different conditions of no PVL, anterior PVL and posterior PVL were experimentally studied and clinically compared. Circulation, impulse, kinetic energy (KE) and change in KE (ΔKE) were calculated. As well, vortex formation analyses and streamline description were performed to study vortex interactions. The anterior PVL jet streamed into the LV and interfered with the transmitral flow. Posterior PVL jet formed a large clockwise vortex and collided with transmitral flow, which resulted in flow disturbance. Compared to no PVL condition, average circulation, impulse, KE and ΔKE increased in presence of PVL. In conclusion, we found that PVL jets lead to abnormal vortex formation that interfere with natural advancement of transmitral flow, and negatively affect the LV fluid dynamics parameters. PVL orifice location strongly affects the intraventricular vortex formation, and posterior PVL may have more negative effects compared to anterior PVL.

Tissue engineering aims to overcome the current limitations of heart valves by providing a viable alternative using living tissue. Nevertheless, the valves constructed from either decellularized xenogeneic or purely biologic scaffolds are unable to withstand the hemodynamic loads, particularly in the left ventricle. To address this, we have been developing a hybrid tissue-engineered heart valve (H-TEHV) concept consisting of a nondegradable elastomeric scaffold enclosed in a valve-like living tissue constructed from autologous cells. We developed a 21 mm mitral valve scaffold for implantation in an ovine model. Smooth muscle cells/fibroblasts and endothelial cells were extracted, isolated, and expanded from the animal's jugular vein. Next, the scaffold underwent a sequential coating with the sorted cells mixed with collagen type I. The resulting H-TEHV was then implanted into the mitral position of the same sheep through open-heart surgery. Echocardiography scans following the procedure revealed an acceptable valve performance, with no signs of regurgitation. The valve orifice area, measured by planimetry, was 2.9 cm², the ejection fraction reached 67%, and the mean transmitral pressure gradient was measured at 8.39 mmHg. The animal successfully recovered from anesthesia and was transferred to the vivarium. Upon autopsy, the examination confirmed the integrity of the H-TEHV, with no evidence of tissue dehiscence. The preliminary results from the animal implantation suggest the feasibility of the H-TEHV.