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1.
J Clin Ultrasound ; 48(4): 216-221, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31833078

RESUMO

PURPOSE: The aim of this study was to investigate myocardial dysfunction and mechanical abnormalities in young patients with Graves' disease before therapy, using two-dimensional speckle tracking echocardiography. METHODS: We performed a comprehensive transthoracic echocardiographic examination, including segmental and global radial strain, and time-to-peak radial strain, in 47 young patients with hyperthyroidism and 34 healthy adults. The time-to-peak radial strain was corrected by RR interval. The variables derived from radial myocardial deformation by the six-basal, six-mid, and six-apical segmental model were compared to investigate the difference of the myocardial function between the two groups. RESULTS: Early diastolic mitral inflow velocity, E/A ratio, early diastolic mitral annular velocity, and e'/a' ratio were lower in patients with Graves' disease than in controls. The left ventricular end-diastolic volume, left ventricular end-systolic volume, stroke volume, cardiac output, heart rate, late diastolic mitral inflow velocity, and late diastolic mitral annular velocity were slightly higher in patients than in controls. Radial strain, global radial strain, and corrected time-to-peak radial strain were lower in the patient group. CONCLUSIONS: The decreased radial strain, global radial strain, and corrected time-to-peak radial strain in young patients with newly diagnosed hyperthyroidism due to Graves' disease could serve as an early sign of subclinical cardiac involvement.


Assuntos
Doença de Graves/complicações , Hipertireoidismo/etiologia , Disfunção Ventricular Esquerda/etiologia , Função Ventricular Esquerda/fisiologia , Adulto , Ecocardiografia/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Hipertireoidismo/diagnóstico por imagem , Hipertireoidismo/fisiopatologia , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiologia , Volume Sistólico/fisiologia , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/fisiopatologia , Adulto Jovem
2.
Bol. méd. postgrado ; 35(2): 47-50, Jul.-Dec. 2019.
Artigo em Espanhol | LILACS, LIVECS | ID: biblio-1120209

RESUMO

El flujo transmitral, a pesar de que su sóla modificación ya no representa un criterio para definir disfunción diastólica, sigue siendo el primer paso para el diagnóstico. El patrón pseudonormal sigue siendo un reto en cuanto a su diferenciación con el patrón normal o anormal en la población, sin embargo resulta interesante conocer la prevalencia de este patrón en poblaciones jóvenes con corazón estructuralmente sano. Para ello, se realizó un estudio descriptivo transversal en 38 pacientes jóvenes con corazón estructuralmente sano, sin enfermedades cardiovasculares previamente diagnosticadas, que acudieron al Centro Cardiovascular Regional ASCARDIO en el período enero-marzo 2019. Se practicó un ecocardiograma transtorácico donde se realizaron determinaciones basales del flujo transmitral y posterior a la aplicación de la maniobra de Handgrip. Los resultados demuestran que el 68% de los pacientes mostraron patrón pseudonormal del flujo transmitral. Al momento de realizar la maniobra de Handgrip, el 84% de los individuos mostraron un patrón de flujo normal mientras el 6% correspondieron a patrón pseudonormal siendo la distribución por sexo equitativa para cada categoría. La maniobra de Handgrip resulta útil para desenmascarar el patrón pseudornomal a normal del flujo transmitral y en sentido contrario, en pacientes con corazón estructuralmente sano(AU)


Transmitral flow, although its single modification no longer represents a criteria to define diastolic dysfunction, remains the first step for diagnosis. The pseudonormal pattern remains a challenge in terms of its differentiation with the normal or abnormal pattern in the population, however it is interesting to know the prevalence of this pattern in young populations with structurally healthy heart. We performed a descriptive transversal study in 38 patients with a structurally healthy heart and no known cardiovascular disease, who attended the Regional Cardiovascular Center ASCARDIO in the period January-March 2019. A transthoracic echocardiogram was performed where baseline determinations of transmitral flow and subsequent to the application of the Handgrip maneuver were made. The results show that 68% of patients had a pseudonormal pattern of transmitral flow. After performing the Handgrip maneuver, 84% of the individuals showed a normal flow pattern while 6% had a pseudonormal pattern, with an equal distribution by sex. Handgrip maneuver is useful to unmask the pseudonormal to normal pattern of transmitral flow and in the opposite direction, in patients with structurally healthy heart(AU)


Assuntos
Humanos , Masculino , Feminino , Adulto , Pressão Sanguínea , Sistema Cardiovascular , Ecocardiografia Doppler , Técnicas de Diagnóstico Cardiovascular , Cardiologia , Doenças Cardiovasculares , Disfunção Ventricular , Valva Mitral/fisiologia
3.
Sci Rep ; 9(1): 16264, 2019 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-31700142

RESUMO

The purpose of this study was to investigate the relationship between isovolumic relaxation flow (IRF) patterns in left ventricle (LV) and mitral inflow patterns. Color Doppler loops were acquired for vector flow mapping in apical long-axis view in 57 patients with coronary artery disease, 31 patients with dilated cardiomyopathy, and 58 healthy controls. IRF patterns were classified into three categories: pattern A, apically directed flow; pattern B, bidirectional flow with small scattered vortices; and pattern C, a large vortex. All normals and patients with normal LV filling (n = 10) showed pattern A. Patients with impaired relaxation consisted of 31 (66%) patients having pattern A, 11 (23%) having pattern B, and 5 (11%) having pattern C. Patients with pseudonormal filling included 4 (31%) patients having pattern A, 7 (54%) having pattern B, and 2 (15%) having pattern C. In patients with restrictive filling, 14 (78%) showed pattern C, 4 (22%) showed pattern B, and no patient showed pattern A. IRF patterns were associated with LV filling patterns (χ2 = 52.026, p < 0.001). There are significant relationships between LV filling and IRF patterns. IRF patterns may provide an index for evaluation of LV diastolic function.


Assuntos
Velocidade do Fluxo Sanguíneo , Diástole , Valva Mitral/fisiologia , Modelos Cardiovasculares , Volume Sistólico , Função Ventricular Esquerda , Adulto , Idoso , Ecocardiografia , Ecocardiografia Doppler , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes
4.
Ultrasound Med Biol ; 45(12): 3172-3185, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31564460

RESUMO

For the quantification of myocardial function, myocardial stiffness can potentially be measured non-invasively using shear wave elastography. Clinical diagnosis requires high precision. In 10 healthy volunteers, we studied the reproducibility of the measurement of propagation speeds of shear waves induced by aortic and mitral valve closure (AVC, MVC). Inter-scan was slightly higher but in similar ranges as intra-scan variability (AVC: 0.67 m/s (interquartile range [IQR]: 0.40-0.86 m/s) versus 0.38 m/s (IQR: 0.26-0.68 m/s), MVC: 0.61 m/s (IQR: 0.26-0.94 m/s) versus 0.26 m/s (IQR: 0.15-0.46 m/s)). For AVC, the propagation speeds obtained on different day were not statistically different (p = 0.13). We observed different propagation speeds between 2 systems (AVC: 3.23-4.25 m/s [Zonare ZS3] versus 1.82-4.76 m/s [Philips iE33]), p = 0.04). No statistical difference was observed between observers (AVC: p = 0.35). Our results suggest that measurement inaccuracies dominate the variabilities measured among healthy volunteers. Therefore, measurement precision can be improved by averaging over multiple heartbeats.


Assuntos
Valva Aórtica/anatomia & histologia , Técnicas de Imagem por Elasticidade/métodos , Valva Mitral/anatomia & histologia , Adulto , Valva Aórtica/fisiologia , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Adulto Jovem
5.
Med Eng Phys ; 74: 121-128, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31564499

RESUMO

Transapical off-pump mitral valve repair with neochord implantation is an established technique for minimally-invasive intervention on mitral valve prolapse/flail. The procedure involves the positioning of artificial chords, whose length/tension is adjusted intraoperatively, adopting different methods based on the experience of the surgeon. This unsystematic approach occasionally leads to complications such as leaflet rupture and excessive/insufficient load on the neochords. In this study, finite element models of a generalized prolapsing mitral valve are used to verify the effect of two alternative tensioning approaches (AT - All together and 1-by-1 - one by one sequences) on the coaptation area and valve biomechanics, comparing results with a corresponding healthy configuration. The total force of about 1 N is exerted by the chords in both strategies, but the maximum stress and coaptation area are closer to those of the healthy configuration in the 1-by-1 sequence. However, the analysis also provides an explanation for the chords unloading in the 1-by-1 strategy observed in the clinical practice, and suggests an optimum tensioning methodology for NeoChord procedures. The study also reveals the potential power of the implemented numerical approach to serve as a tool for procedural planning, supporting the identification of the most suitable ventricular access site and the most effective stitching points for the artificial chords.


Assuntos
Circulação Coronária , Valva Mitral/fisiologia , Modelos Cardiovasculares , Estresse Mecânico , Fenômenos Biomecânicos
6.
Echocardiography ; 36(9): 1646-1655, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31544286

RESUMO

BACKGROUND: Automatic quantification of left ventricular (LV) function could enhance workflow for cardiologists and assist inexperienced clinicians who perform focused cardiac ultrasound. We have developed an algorithm for automatic measurements of the mitral annular plane systolic excursion (MAPSE) and peak velocities in systole (S') and early (e') and late (a') diastole. We aimed to establish normal reference values for the automatic measurements and to compare them with manual measurements. METHODS AND RESULTS: Healthy participants (n = 1157, 52.5% women) from the HUNT3 cross-sectional population study in Norway were included. The mean age ± standard deviation (SD) was 49 ± 14 (range: 19-89) years. The algorithm measured MAPSE, S', e', and a' from apical 4-chamber color tissue Doppler imaging (cTDI) recordings. The manual measurements were obtained by two echocardiographers, who measured MAPSE by M-mode and the velocities by cTDI. For men and women, age-specific reference values were created for groups (mean ± 1.96SD) and by linear regression (mean, 95% prediction interval). Age was negatively correlated with MAPSE, S', and e' and positively correlated with a'. There were small differences between genders. Normal reference ranges were created. The coefficients of variation between automatic and manual measurements ranged from 5.5% (S') to 11.7% (MAPSE). CONCLUSION: Normal reference values for automatic measurements of LV function indices are provided. The automatic measurements were in line with the manual measurements. Implementing automatic measurements and comparison with normal ranges in ultrasound scanners can allow for quick and precise interpretation of LV function.


Assuntos
Ecocardiografia Doppler , Valva Mitral/diagnóstico por imagem , Valva Mitral/fisiologia , Função Ventricular Esquerda/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Velocidade do Fluxo Sanguíneo/fisiologia , Estudos Transversais , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Noruega , Valores de Referência , Sístole/fisiologia
7.
Int J Numer Method Biomed Eng ; 35(11): e3254, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31454470

RESUMO

We present a coupled left atrium-mitral valve model based on computed tomography scans with fibre-reinforced hyperelastic materials. Fluid-structure interaction is realised by using an immersed boundary-finite element framework. Effects of pathological conditions, eg, mitral valve regurgitation and atrial fibrillation, and geometric and structural variations, namely, uniform vs non-uniform atrial wall thickness and rule-based vs atlas-based fibre architectures, on the system are investigated. We show that in the case of atrial fibrillation, pulmonary venous flow reversal at late diastole disappears, and the filling waves at the left atrial appendage orifice during systole have reduced magnitude. In the case of mitral regurgitation, a higher atrial pressure and disturbed flows are seen, especially during systole, when a large regurgitant jet can be found with the suppressed pulmonary venous flow. We also show that both the rule-based and atlas-based fibre defining methods lead to similar flow fields and atrial wall deformations. However, the changes in wall thickness from non-uniform to uniform tend to underestimate the atrial deformation. Using a uniform but thickened wall also lowers the overall strain level. The flow velocity within the left atrial appendage, which is important in terms of appendage thrombosis, increases with the thickness of the left atrial wall. Energy analysis shows that the kinetic and dissipation energies of the flow within the left atrium are altered differently by atrial fibrillation and mitral valve regurgitation, providing a useful indication of the atrial performance in pathological situations.


Assuntos
Átrios do Coração/anatomia & histologia , Valva Mitral/fisiologia , Modelos Cardiovasculares , Fibrilação Atrial/fisiopatologia , Velocidade do Fluxo Sanguíneo , Análise de Elementos Finitos , Átrios do Coração/diagnóstico por imagem , Humanos , Valva Mitral/anatomia & histologia , Valva Mitral/diagnóstico por imagem , Tomografia Computadorizada por Raios X
8.
Comput Methods Biomech Biomed Engin ; 22(15): 1229-1238, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31437018

RESUMO

Vortex structures, as one of the most important features of cardiac flow, have a crucial impact on the left ventricle function and pathological conditions. These swirling flows are closely related to the presence of turbulence in left ventricle which is investigated in the current study. Using an extended model of the left heart, including a fluid-structure interaction (FSI) model of the mitral valve with a realistic geometry, the effect of using two numerical turbulent models, k-ε and Spalart-Allmaras (SA), on diastolic flow patterns is studied and compared with results from laminar flow model. As a result of the higher dissipation rate in turbulent models (k-ε and SA), vortices are larger and stronger in the laminar flow model. Comparing E/A ratio in the three models (Laminar, k-ε, and SA) with experimental data from healthy subjects, it is concluded that the results from k-ε model are more accurate.


Assuntos
Simulação por Computador , Circulação Coronária/fisiologia , Modelos Cardiovasculares , Função Ventricular/fisiologia , Velocidade do Fluxo Sanguíneo , Humanos , Valva Mitral/fisiologia , Análise Numérica Assistida por Computador , Pressão , Estresse Mecânico
9.
Int J Numer Method Biomed Eng ; 35(11): e3240, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31330567

RESUMO

This work is concerned with modeling and simulation of the mitral valve, one of the four valves in the human heart. The valve is composed of leaflets, the free edges of which are supported by a system of chordae, which themselves are anchored to the papillary muscles inside the left ventricle. First, we examine valve anatomy and present the results of original dissections. These display the gross anatomy and information on fiber structure of the mitral valve. Next, we build a model valve following a design-based methodology, meaning that we derive the model geometry and the forces that are needed to support a given load and construct the model accordingly. We incorporate information from the dissections to specify the fiber topology of this model. We assume the valve achieves mechanical equilibrium while supporting a static pressure load. The solution to the resulting differential equations determines the pressurized configuration of the valve model. To complete the model, we then specify a constitutive law based on a stress-strain relation consistent with experimental data that achieves the necessary forces computed in previous steps. Finally, using the immersed boundary method, we simulate the model valve in fluid in a computer test chamber. The model opens easily and closes without leak when driven by physiological pressures over multiple beats. Further, its closure is robust to driving pressures that lack atrial systole or are much lower or higher than normal.


Assuntos
Valva Mitral/anatomia & histologia , Modelos Cardiovasculares , Pressão Sanguínea , Elasticidade , Ventrículos do Coração/anatomia & histologia , Humanos , Valva Mitral/fisiologia
10.
Acta Biomater ; 96: 368-384, 2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260822

RESUMO

Atrioventricular heart valves (AHVs) are composed of structurally complex and morphologically heterogeneous leaflets. The coaptation of these leaflets during the cardiac cycle facilitates unidirectional blood flow. Valve regurgitation is treated preferably by surgical repair if possible or replacement based on the disease state of the valve tissue. A comprehensive understanding of valvular morphology and mechanical properties is crucial to refining computational models, serving as a patient-specific diagnostic and surgical tool for preoperative planning. Previous studies have modeled the stress distribution throughout the leaflet's thickness, but validations with layer-specific biaxial mechanical experiments are missing. In this study, we sought to fill this gap in literature by investigating the impact of microstructure constituents on mechanical behavior throughout the thickness of the AHVs' anterior leaflets. Porcine mitral valve anterior leaflets (MVAL) and tricuspid valve anterior leaflets (TVAL) were micro-dissected into three layers (atrialis/spongiosa, fibrosa, and ventricular) and two layers (atrialis/spongiosa and fibrosa/ventricularis), respectively, based on their relative distributions of extracellular matrix components as quantified by histological analyses: collagen, elastin, and glycosaminoglycans. Our results suggest that (i) for both valves, the atrialis/spongiosa layer is the most extensible and anisotropic layer, possibly due to its relatively low collagen content as compared to other layers, (ii) the intact TVAL response is stiffer than the atrialis/spongiosa layer but more compliant than the fibrosa/ventricularis layer, and (iii) the MVAL fibrosa and ventricularis layers behave nearly isotropic. These novel findings emphasize the biomechanical variances throughout the AHV leaflets, and our results could better inform future AHV computational model developments. STATEMENT OF SIGNIFICANCE: This study, which is the first of its kind for atrioventricular heart valve (AHV) leaflet tissue layers, rendered a mechanical characterization of the biaxial mechanical properties and distributions of extracellular matrix components (collagen, elastin, and glycosaminoglycans) of the mitral and tricuspid valve anterior leaflet layers. The novel findings from the present study emphasize the biomechanical variances throughout the thickness of AHV leaflets, and our results indicate that the previously-adopted homogenous leaflet in the AHV biomechanical modeling may be an oversimplification of the complex leaflet anatomy. Such improvement in the understanding of valvular morphology and tissue mechanics is crucial to future refinement of AHV computational models, serving as a patient-specific diagnostic and surgical tool, at the preoperative stage, for treating valvular heart diseases.


Assuntos
Valva Mitral/fisiologia , Valva Tricúspide/fisiologia , Animais , Anisotropia , Fenômenos Biomecânicos , Valva Mitral/citologia , Suínos , Valva Tricúspide/citologia
11.
J Biomech ; 90: 50-57, 2019 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-31053473

RESUMO

MRI-based computational fluid dynamics simulations were performed in the left ventricles of two adult porcine subjects with varying physiological states (before and after an induced infarction). The hypothesis that diastolic vortices store kinetic energy and assist systolic ejection was tested, by performing systolic simulations in the presence and absence of diastolic vortices. The latter was achieved by reinitializing the entire velocity field to be zero at the beginning of systole. A rudimentary prescribed motion model of a mitral valve was included in the simulations to direct the incoming mitral jet towards the apex. Results showed that the presence or absence of diastolic vortex rings had insignificant impact on the energy expended by walls of the left ventricles for systolic ejection for both the porcine subjects, under all physiological conditions. Although substantial kinetic energy was stored in diastolic vortices by end diastole, it provided no appreciable savings during systolic ejection, and most likely continued to complete dissipation during systole. The role of diastolic vortices in apical washout was investigated by studying the cumulative mass fraction of passive dye that was ejected during systole in the presence and absence of vortices. Results indicated that the diastolic vortices play a crucial role in ensuring efficient washout of apical blood during systolic ejection.


Assuntos
Diástole/fisiologia , Hidrodinâmica , Sístole/fisiologia , Animais , Velocidade do Fluxo Sanguíneo , Simulação por Computador , Feminino , Cinética , Imagem por Ressonância Magnética , Masculino , Valva Mitral/diagnóstico por imagem , Valva Mitral/fisiologia , Suínos , Função Ventricular Esquerda/fisiologia
12.
Development ; 146(12)2019 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-30796046

RESUMO

Heart valve cells mediate extracellular matrix (ECM) remodeling during postnatal valve leaflet stratification, but phenotypic and transcriptional diversity of valve cells in development is largely unknown. Single cell analysis of mouse heart valve cells was used to evaluate cell heterogeneity during postnatal ECM remodeling and leaflet morphogenesis. The transcriptomic analysis of single cells from postnatal day (P)7 and P30 murine aortic (AoV) and mitral (MV) heart valves uncovered distinct subsets of melanocytes, immune and endothelial cells present at P7 and P30. By contrast, interstitial cell populations are different from P7 to P30. P7 valve leaflets exhibit two distinct collagen- and glycosaminoglycan-expressing interstitial cell clusters, and prevalent ECM gene expression. At P30, four interstitial cell clusters are apparent with leaflet specificity and differential expression of complement factors, ECM proteins and osteogenic genes. This initial transcriptomic analysis of postnatal heart valves at single cell resolution demonstrates that subpopulations of endothelial and immune cells are relatively constant throughout postnatal development, but interstitial cell subpopulations undergo changes in gene expression and cellular functions in primordial and mature valves.


Assuntos
Valva Aórtica/crescimento & desenvolvimento , Matriz Extracelular/química , Valva Mitral/crescimento & desenvolvimento , Animais , Valva Aórtica/fisiologia , Diferenciação Celular , Linhagem da Célula , Análise por Conglomerados , Colágeno/química , Células Endoteliais/citologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Marcadores Genéticos , Glicosaminoglicanos/química , Homeostase , Humanos , Imuno-Histoquímica , Masculino , Melanócitos/citologia , Camundongos , Valva Mitral/fisiologia , Fenótipo , Análise de Sequência de RNA , Análise de Célula Única/métodos , Suínos , Engenharia Tecidual/métodos , Transcriptoma
13.
Exp Biol Med (Maywood) ; 244(3): 241-251, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30722697

RESUMO

IMPACT STATEMENT: This work is important to the field of heart valve pathophysiology as it provides new insights into molecular markers of mechanically induced valvular degeneration as well as the protective role of the valvular endothelium. These discoveries reported here advance our current knowledge of the valvular endothelium and how its removal essentially takes valve leaflets into an environmental shock. In addition, it shows that static conditions represent a mild pathological state for valve leaflets, while 10% cyclic stretch provides valvular cell quiescence. These findings impact the field by informing disease stages and by providing potential new drug targets to reverse or slow down valvular change before it affects cardiac function.


Assuntos
Endotélio/fisiologia , Valva Mitral/fisiologia , Estresse Mecânico , Animais , Proteoma/análise , Suínos
14.
Ultrasound Obstet Gynecol ; 54(2): 225-231, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30251286

RESUMO

OBJECTIVE: Maternal hemodynamics in pregnancy is associated with fetal growth and birth weight, which in turn are associated with offspring cardiovascular disease later in life. The aim of this study was to quantify the extent to which birth weight is associated with cardiac structure and function in adolescence. METHODS: A subset of offspring (n = 1964; 55% female) of the Avon Longitudinal Study of Parents and Children were examined with echocardiography at a mean age of 17.7 (SD, 0.3) years. The associations of birth-weight Z-score for sex and gestational age with cardiac structure (assessed by relative wall thickness, left ventricular mass index (LVMI) and left atrial diameter index), systolic function (assessed by ejection fraction and left ventricular wall velocity) and diastolic function (assessed by early/late mitral inflow velocity (E/A) and early mitral inflow velocity/mitral annular early diastolic velocity (E/e')) were evaluated. Linear regression models were adjusted for several potential confounders, including maternal prepregnancy body mass index, age, level of education and smoking during pregnancy. RESULTS: Higher birth-weight Z-score was associated with lower E/A (mean difference, -0.024; 95% CI, -0.043 to -0.005) and E/e' (mean difference, -0.05; 95% CI, -0.10 to -0.001) and higher LVMI (mean difference, 0.38 g/m2.7 ; 95% CI, 0.09 to 0.67). There was no or inconsistent evidence of associations of birth-weight Z-score with relative wall thickness, left atrial diameter and measurements of systolic function. Further analyses suggested that the association between birth-weight Z-score and LVMI was driven mainly by an association observed in participants born small-for-gestational age and it did not persist when risk factors in adolescence were accounted for. CONCLUSIONS: Higher birth weight adjusted for sex and gestational age was associated with differences in measures of diastolic function in adolescence, but the observed associations were small. It remains to be determined the extent to which these associations translate into increased susceptibility to cardiovascular disease later in life. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.


Assuntos
Peso ao Nascer/fisiologia , Ecocardiografia/métodos , Desenvolvimento Fetal/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Adolescente , Fenômenos Fisiológicos Cardiovasculares , Diástole/fisiologia , Feminino , Retardo do Crescimento Fetal/diagnóstico por imagem , Retardo do Crescimento Fetal/epidemiologia , Retardo do Crescimento Fetal/fisiopatologia , Idade Gestacional , Hemodinâmica , Humanos , Estudos Longitudinais , Masculino , Valva Mitral/diagnóstico por imagem , Valva Mitral/fisiologia , Pais , Gravidez , Fatores de Risco , Fatores Sexuais , Volume Sistólico/fisiologia
15.
NMR Biomed ; 32(1): e4022, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30403426

RESUMO

Intracardiac blood flow patterns are affected by the morphology of cardiac structures and are set up to support the heart's pump function. Exercise affects contractility and chamber size as well as pre- and afterload. The aim of this study was to test the feasibility of four-dimensional phase contrast cardiovascular MRI under pharmacological stress and to study left ventricular blood flow under stress. 4D flow data were successfully acquired and analysed in 12 animals. During dobutamine infusion, heart rate and ejection fraction increased (82 ± 5 bpm versus 124 ± 3 bpm/46 ± 9% versus 65 ± 7%; both p < 0.05). A decrease in left ventricular end-diastolic volume (72 ± 14 mL versus 55 ± 8 mL; p < 0.05) and end-systolic volume (40 ± 15 mL versus 19 ± 6 mL; p < 0.05) but no change in stroke volume were observed. Trans-mitral diastolic inflow velocity increased under dobutamine and the trajectory of inflowing blood was directed towards the anterior septum with increased inflow angle (26 ± 5°) when compared with controls (15 ± 2°). In 5/6 animals undergoing stress diastolic vortices developed later, and in 3/6 animals vortices collapsed earlier with significantly smaller cross-sectional area during diastole. The vorticity index was not affected. Under the stress condition direct flow (% ejection within the next heart beat) increased from 43 ± 6% to 53 ± 8%. 4D MRI blood flow acquisition and analysis are feasible in pig hearts under dobutamine-induced stress. Flow patterns characterized by high blood velocity and antero-septally oriented diastolic inflow as well as decreased ventricular volumes are unfavourable conditions for diastolic vortex development under pharmacological stress, and cardiac output is increased by a rise in heart rate and directly ejected left ventricular blood volume.


Assuntos
Circulação Coronária/efeitos dos fármacos , Dobutamina/farmacologia , Ventrículos do Coração/efeitos dos fármacos , Descanso , Estresse Fisiológico/efeitos dos fármacos , Animais , Diástole/efeitos dos fármacos , Imageamento Tridimensional , Valva Mitral/efeitos dos fármacos , Valva Mitral/fisiologia , Suínos
16.
Artigo em Inglês | MEDLINE | ID: mdl-29993542

RESUMO

Echocardiography is widely used to provide critical left ventricular indices describing myocardial motion and blood inflow velocity. Tissue motion and blood flow are strongly connected and interdependent in the ventricle. During cardiac relaxation, rapid filling leads to the formation of a vortical blood flow pattern. In this paper, we introduce a high-frame-rate method to track vortex dynamics alongside myocardium motion, in a single heartbeat. Cardiac triplex imaging (B-mode + tissue Doppler + color Doppler) was obtained by insonating the left ventricle with diverging waves. We used coherent compounding with integrated motion compensation to obtain high-quality B-mode images. Tissue Doppler was retrieved and the septal and lateral velocities of the mitral annulus were deduced. A rate of ~80 triplex images/s was obtained. Vortex dynamics was analyzed by Doppler vortography. Blood vortex signature maps were used to track the vortex and compute core vorticities. The sequence was implemented in a Verasonics scanner with a 2.5-MHz phased array and tested in vivo in 12 healthy volunteers. Two main peaks appeared on the vorticity curves. These peaks were synchronized with the mitral inflow velocities with a small delay. We observed a relationship between the tissue and vortex waveforms, though also with a delay, which denoted the lag between the wall and the flow motion. Clinical diastolic indices combining basal and mitral inflow velocities (E/A ratio and E/ e' ratio) were determined and compared with those measured using a conventional ultrasound scanner; a good correlation was obtained ( r2 = 0.96 ). High-frame-rate Doppler echocardiography enabled us to retrieve time-resolved dynamics of the myocardium and vortex flow within the same cardiac cycle. Coupling wall-flow analysis could be of clinical relevance for early diagnosis of filling impairment.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Ecocardiografia Doppler/métodos , Coração/diagnóstico por imagem , Coração/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Humanos , Valva Mitral/diagnóstico por imagem , Valva Mitral/fisiologia
17.
Acta Biomater ; 85: 241-252, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30579963

RESUMO

BACKGROUND: Healthy function of tricuspid valve (TV) structures is essential to avoid tricuspid regurgitation (TR) and may significantly improve disease prognosis. Mitral valve (MV) structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Therefore, clinical decisions and finite element (FE) simulations often rely heavily on MV data for TV applications, despite fundamentally different mechanical and physiological environments. METHOD/RESULTS: To bridge this gap, we performed a rigorous mechanical, morphological, and microstructural characterization of the MV and TV leaflets and chordae in a porcine model. Planar biaxial testing, uniaxial testing, second harmonic generation imaging and Verhoeff Van Gieson staining were performed. Morphological parameters, tissue moduli, extensibility, and anisotropy were quantified and compared. No major differences in leaflet mechanics or structure were found between TV and MV; chordal mechanics, morphology, and structure were found to compensate for anatomical and physiological loading differences between the valves. No differences in chordal mechanics were observed by insertion point within a leaflet; the septal tricuspid leaflet (STL) and posterior mitral leaflet (PML) did not have distinguishable strut chords, and the STL had the shortest chords. Within a valve, chords from septally-located leaflets were more extensible. MV chords were stiffer. CONCLUSIONS: This study presents the first rigorous comparative mechanical and structural dataset of MV and TV structures. Valve type and anatomical location may be stronger predictors of chordal mechanics. Chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications. STATEMENT OF SIGNIFICANCE: A better understanding of the tricuspid valve (TV) and its associated structures is important for making advancements towards the repair of tricuspid regurgitation. Mitral valve structures have been extensively studied, but little is known about the TV and right-sided heart diseases. Clinical decisions and computational simulations often rely heavily on MV data for TV applications, despite fundamentally different environments. We therefore performed a rigorous mechanical, morphological, and microstructural characterization of atrioventricular leaflets and chordae tendineae in a porcine model. Finding that valve type and anatomical location may be strong predictors of chordal mechanics, chords from septally-located leaflets differ from each other and from their intravalvular counterparts; they merit special consideration in surgical and computational applications.


Assuntos
Cordas Tendinosas/anatomia & histologia , Cordas Tendinosas/fisiologia , Valva Mitral/anatomia & histologia , Valva Mitral/fisiologia , Valva Tricúspide/anatomia & histologia , Valva Tricúspide/fisiologia , Animais , Fenômenos Biomecânicos , Modelos Biológicos , Suínos
18.
Orv Hetil ; 159(50): 2129-2135, 2018 Dec.
Artigo em Húngaro | MEDLINE | ID: mdl-30545264

RESUMO

INTRODUCTION: Morphology and function of the mitral annulus (MA) shows alterations in different valvular (for instance in mitral regurgitation) and non-valvular disorders (for instance in certain cardiomyopathies, cardiac amyloidosis). AIM: The aim of the present study was to examine the relationship between MA morphologic and functional properties and three-dimensional speckle-tracking echocardiography- (3DSTE) derived left ventricular (LV) ejection fraction (EF) in subjects with normal versus borderline LV-EF. METHOD: The present study comprised 146 volunteers (mean age: 32.0 ± 11.4 years; 74 males) in whom complete two-dimensional Doppler echocardiography was performed with a negative result extended with 3DSTE. The population was further divided into two groups according to their 3DSTE-derived LV-EF (borderline 50-54% versus ≥55%). RESULTS: In cases with borderline LV-EF, higher LV end-systolic LV volumes and lower LV longitudinal strain could be measured. All end-systolic and end-diastolic MA diameter, area and perimeter data proved to be higher in cases with borderline LV-EF. In these subjects, MA functional parameters proved to be lower as well. In contrast, LV-EF showed correlations neither with end-systolic and end-diastolic MA dimensions nor with MA functional parameters. CONCLUSIONS: 3DSTE-derived borderline LV-EF is associated with MA dilatation and functional impairment. Orv Hetil. 2018; 159(50): 2129-2135.


Assuntos
Ecocardiografia Doppler/métodos , Átrios do Coração/diagnóstico por imagem , Valva Mitral/diagnóstico por imagem , Adulto , Função Atrial/fisiologia , Ecocardiografia Tridimensional/métodos , Feminino , Ventrículos do Coração/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiologia , Tamanho do Órgão
19.
J Vis Exp ; (141)2018 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-30582607

RESUMO

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular (LV) filling compared with a continuous linear jet. Vortex ring development is most often quantified with vortex formation time (VFT), a dimensionless parameter based on fluid ejection from a rigid tube. Our group is interested in factors that affect LV filling efficiency during cardiac surgery. In this report, we describe how to use standard two-dimensional (2D) and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables needed to calculate VFT. We calculate atrial filling fraction (ß) from velocity-time integrals of trans-mitral early LV filling and atrial systole blood flow velocity waveforms measured in the mid-esophageal four-chamber TEE view. Stroke volume (SV) is calculated as the product of the diameter of the LV outflow track measured in the mid-esophageal long axis TEE view and the velocity-time integral of blood flow through the outflow track determined in the deep transgastric view using pulse-wave Doppler. Finally, mitral valve diameter (D) is determined as the average of major and minor axis lengths measured in orthogonal mid-esophageal bicommissural and long axis imaging planes, respectively. VFT is then calculated as 4 × (1-ß) × SV/(πD3). We have used this technique to analyze VFT in several groups of patients with differing cardiac abnormalities. We discuss our application of this technique and its potential limitations and also review our results to date. Noninvasive measurement of VFT using TEE is straightforward in anesthetized patients undergoing cardiac surgery. The technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.


Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Ecocardiografia Doppler/métodos , Ecocardiografia Transesofagiana/métodos , Cardiopatias/diagnóstico por imagem , Cardiopatias/cirurgia , Monitorização Intraoperatória/métodos , Idoso , Velocidade do Fluxo Sanguíneo/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/fisiopatologia , Hemodinâmica/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Valva Mitral/fisiologia , Volume Sistólico/fisiologia , Fatores de Tempo , Função Ventricular Esquerda/fisiologia
20.
J Heart Valve Dis ; 27(1): 32-37, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30560597

RESUMO

BACKGROUND: Currently, several different flexible mitral annuloplasty rings are available, and their efficacy for surgical repair of the mitral valve is, in general, considered equal. However, clinical experience indicates differences in remodeling capacity that have not yet been quantitatively assessed. The study aim was to compare the biomechanical properties of two commonly used flexible mitral annuloplasty rings in an acute pig model. METHODS: Medtronic Simulus Flex (n = 5) and Medtronic Duran AnCore (n = 7) flexible mitral annuloplasty rings were implanted in pigs (bodyweight 80 kg). The native mitral valve was used as a reference (n = 7). Mitral annular dynamics and dimensions were assessed using 11 sonomicrometry crystals placed in the mitral apparatus. A dedicated force transducer was used to detect deformational force transmission between the annuloplasty ring and the mitral annulus. RESULTS: Cyclic changes in mitral annular circumference and commissure-commissure distance were significantly reduced in the Simulus Flex group compared to the Duran AnCore group (p = 0.025 and p <0.01, respectively). In the Simulus Flex group, smaller deformational forces were recorded compared to the Duran AnCore group, but the difference was not statistically significant (p = 0.52 and p = 0.06 for the septal-lateral and the commissure-commissure force measurements, respectively). CONCLUSIONS: The Simulus Flex ring showed significantly more remodeling capacity than the Duran AnCore ring, but the latter ring preserved the natural dynamics of the mitral valve to a greater degree. Insights into these biomechanical differences may facilitate strategies for surgical reconstruction in degenerative mitral valve disease, especially in patients with excessive amounts of tissue and who are at risk of systolic anterior motion of the mitral valve.


Assuntos
Próteses Valvulares Cardíacas , Anuloplastia da Valva Mitral/instrumentação , Valva Mitral/cirurgia , Animais , Fenômenos Biomecânicos , Modelos Animais de Doenças , Valva Mitral/fisiologia , Desenho de Prótese , Suínos
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