A left ventricular assist device is a mechanical pump implanted in patients with heart failure that continuously takes blood from the left ventricle and delivers it to the aorta, thus decreasing ventricular load. The device is typically considered as a ‘bridge to transplant’, i.e. as a temporary therapy, and involves several risks. Modified ventricular hemodynamics due to a heart pump implantation is studied in-vitro using an elastic ventricle. The ventricle is incorporated into a pulse duplicator setup, which prescribes realistic pulsatile inflow/outflow to mimic a weak ejection fraction. A continuous axial pump mimics a ventricular assist device and its effect on the ventricular hemodynamics is investigated as a function of the pump flow suction. Using particle image velocimetry, pump flow effectiveness at providing unloading on the ventricle and increasing ejection is observed and understanding if proper recirculation of the myocardium down to the apex is restored under varying flow rate.

In an average year more than 1.7 million people will experience a traumatic brain injury (TBI) in the United States. It is known that atrophy occurs across a spectrum for TBI patients, ranging from mild to severe. Current conventional magnetic resonance imaging (MRI) methods are inconsistent in detecting this atrophy on the milder end of the spectrum. Also more contemporary imaging tools, although efficient, are too time consuming for clinical applicability. It is for these reasons that a quick and efficient measurement for detecting this atrophy is needed by clinicians. The measuring of third ventricle width had the potential to be this measurement, since it is known that ventricular dilation is an indirect measure of brain atrophy. This study used two different data sets acquired at multiple sites. A total of 152 TBI patients' MRI scans were analyzed with diagnosis ranging from mild to severe. They have been age matched with 97 orthopedic injury controls. All scans were analyzed using Freesurfer® auto-segmentation software to acquire cortical, subcortical, and ventricular volumes. These metrics were then used as a standard of efficacy which we tested the new third ventricle width protocol against. There was no statistically significant difference between the overall TBI group and OI group (Welch's F(1,238.435) = 1.091, p= .267). The complicated mild injury subgroup was significantly increased from the mild subgroup (p= .001, d= .87). The grand average third ventricle width measurement was the best prognosticator of all measures analyzed despite only predicting 35.1% of cases correctly. The findings suggest that the third ventricle width measurement is insensitive to atrophy between all groups as hypothesized.

No description available.

No description available.

Heart disease is one of the primary causes of morbidity and mortality for the adult population over the age of 65. Furthermore, ailments such as hypertension can affect as many as 50% of the adult population over the age of 45. If left untreated, these ailments eventually precipitate the onset of diastolic dysfunction and heart failure. Diastolic dysfunction is the alteration or impairment of performance in either the left or right ventricle of the heart. Although there has been a marked increase in study of this disease, there is still an apparent difficulty to diagnose patients. Flow visualization techniques have been commonly employed to study the development of these diseases as they relate to the filling process of the ventricles. One method, Echo Particle Image Velocimetry (Echo-PIV) is a relatively new method for cardiac flow chamber visualization, with the potential to provide physicians with a cost-effective and safe method for obtaining high temporal resolution recordings for extending knowledge on the filling processes in cardiac chamber flow. This work presents a new approach to extending the capabilities of Echo-PIV for more accurate measurement of cardiac flows for patients with poor quality recordings. Currently, much of the literature notes that temporal resolution and poor acoustic windows results in exclusion from study. These recordings are more representative of the contrast-enhancement studies used by physicians to better identify chamber walls. When applying standard PIV cross-correlation techniques, measurements tend to fail due to image noise and artifacts. By implementing a Moving Ensemble (MWE) with Product of Correlation (PoC) processing scheme, measurement accuracy, reliability, and robustness can be obtained for measurement in left ventricular filling assessment. / Master of Science

Background: Coarctation of the aorta (CoA) is a congenital heart disease which represents a narrowing of the proximal descending aorta, hence increasing pressure afterload to the left ventricle (LV). Conventional treatment of native CoA is surgical repair, however potential recurrence or other related complications e.g. aortic rupture, heart failure and cerebrovascular events are common. Thus, lifelong follow-up of these patients is required. Echocardiography is the most patient’s friendly method to evaluate CoA and in particular its effect on LV function. Moreover, the novel speckle tracking echocardiography (STE) is an important method to assess subclinical LV dysfunction, a technique that promises better evaluation of LV function in these patients. The aims of this thesis were to review the literature on LV function in children with CoA using myocardial deformation imaging technologies, hence, to better understand the current knowledge and vagueness of the scientific evidence. We also aimed to study the effect of early CoA repair on the structure and function of LV and ascending aorta. In addition, we wished to establish in a meta-analysis format normal values of speckle tracking derived strain and strain rate values. Methods: Study 1. We have systematically searched the PubMed, and studies that fulfilled the inclusion criteria were critically analyzed and presented on a narrative form. Study 2 and 3. In addition to conventional echocardiographic measures of LV and ascending aorta, we measured longitudinal strain and strain rate of the LV using a vendor independent software, TomTec. We have also measured the aorto-septal angle (AoSA). Data was compared with normal healthy controls. Study 4. Electronic databases were systematically searched and suitable studies were meta analyzed using Comprehensive meta-analysis version 3 software. Results: Study 1. In 7/4945 included articles, 123 and 76 patients with congenital aortic stenosis (CAS) and CoA were reported, respectively. Normal conventional LV function, with subclinical myocardial dysfunction were reported in all studies before intervention. After intervention, a consistent improvement of myocardial deformation parameters was documented, even though not reaching normal values. Study 2. In 21 patients with CoA, LV function significantly improved after intervention (p <0.001), however normal values were not reached even at medium-term follow-up (p = 0.002). Medium-term longitudinal strain correlated with pre intervention LV ejection faction (EF) (r = 0.58, p = 0.006). Medium-term subnormal values were more frequently associated with Bicuspid aortic valve (BAV) (33.3% vs. 66.6%; p <0.05). Study 3. AoSA was abnormally wide before intervention, in particular at peak ejection in the descending aorta (p <0.0001), and correlated with CoA pressure gradient. After intervention, AoSA normalized and significantly correlated with the increase of LV cavity function and overall LV deformation parameters. Study 4. In a meta-analysis of 28/282 studies including 1192 subjects, strain and strain rate values were established. Longitudinal strain normal mean values varied from -12.9 to -26.5 (mean, -20.5; 95 % CI, -20.0 to -21.0). Normal mean values of circumferential strain varied from -10.5 to -27.0 (mean, -22.06; 95 % CI, -21.5 to -22.5). Radial strain normal mean values varied from 24.9 to 62.1 (mean, 45.4; 95 % CI, 43.0 to 47.8). Meta-regression showed LV end-diastolic diameter as a significant determinant of variation of longitudinal strain. Longitudinal systolic strain rate was significantly determined by age and radial strain was influenced by the type of vendor used. Conclusion: The systematic review showed subclinical LV dysfunction in children with CoA before and after correction. However, since most of the patients were operated at an older age and had preserved LV EF, the effect of early intervention on LV function was only speculated. Our children with CoA who were operated at an earlier age showed LV subclinical dysfunction even at medium- term after intervention while the AoSA returned to normal shortly after intervention. Lower longitudinal strain values were found in patients with LV dysfunction (LV EF <50%) before intervention and BAV. Finally, normal range values for strain and strain rate have been established and seem to be influenced by patients’ age, LV end-diastolic diameter and vendor used.

A avaliação do ventrículo esquerdo (VE) é uma das principais contribuições da ecocardiografia no estudo da função cardíaca e inclui a mensuração dos diâmetros da cavidade e espessura das paredes em diástole e sístole. O estudo por meio do modo M tem sido usado como padrão para a realização da mensuração e para o cálculo de índices sistólicos, mas o modo bidimensional também é utilizado para este fim. As medidas podem ser adquiridas a partir de dois planos de imagem: transversal e longitudinal. A definição de intervalos de confiança para valores normais de VE permite a identificação de remodelamento ventricular, concêntrico ou excêntrico, decorrente de doenças cardiovasculares ou sistêmicas. Assim sendo, o objetivo deste estudo foi comparar as medidas ecocardiográficas desta câmara obtidas pelos seguintes métodos: modo M em corte transversal, modo M em corte longitudinal, modo bidimensional em corte transversal e modo bidimensional em corte longitudinal. Adicionalmente, estudou-se o comportamento do efeito do peso e do sexo nos métodos mencionados. Foram selecionados 40 cães adultos da raça Pastor Alemão sem alterações cardiovasculares. A realização do ecocardiograma de cada animal inclui os quatro métodos descritos acima, de acordo com o recomendado pela literatura. Foram pesquisados os efeitos do corte e do método, bem como a influência do peso e do sexo, sobre cada medida estudada, linear ou derivada. O peso apresentou correlação com todas as medidas lineares de VE em pelo menos um dos métodos, mas não com fração de encurtamento (FE) e fração de ejeção (FEj). Utilizando-se a análise univariada, verificou-se que machos apresentaram todas as medidas estudadas significativamente maiores que fêmeas em pelo menos um dos métodos, exceto FE e FEj, cujos valores não foram diferentes entre os sexos. Observou-se efeito isolado do corte apenas sobre diâmetro diastólico final do ventrículo esquerdo (DdFVE), com medidas maiores obtidas no corte transversal, e mudança de comportamento do sexo nos cortes com influência significativa do peso sobre septo interventricular em diástole (SIVd). Houve efeito isolado do modo sobre os índices de função sistólica FE e FEj, com valores maiores fornecidos pelo modo M. O peso teve efeito isolado positivo sobre parede livre de ventrículo esquerdo em diástole (PLVEd), exceto no modo M em corte transversal e (diâmetro sistólico final de ventrículo esquerdo (DsFVE). O sexo, retirada a influência do peso, teve efeito isolado apenas sobre DdFVE, com machos apresentando valores significativamente maiores que fêmeas em ambos os cortes no modo bidimensional. Os resultados Os resultados mostram que há risco de erro de interpretação quando valores normais de referência, gerados a partir de determinado método, são utilizados para a avaliação de um paciente examinado por técnica de mensuração diversa, especialmente quando se obtém resultados nos limites superior ou inferior de normalidade. / Left ventricle (LV) evaluation is one of the most important contributions of echocardiography in the assessment of cardiac function. It includes measurements of internal diameter and wall thickness at end-diastole and end-sistole of this chamber. M Mode echocardiography has been widely used for measuring linear dimensions and quantifying systolic function, but bidimensional mode is also used with the same purpose. The LV measurement can be derived from transverse or longitudinal images of the heart. The establishment of normal confidence intervals of LV dimensions allows identification of concentric or excentric ventricular remodeling process secondary to cardiovascular and systemic diseases. The aim of this study was to compare LV measurements obtained from four methods: M mode in short-axis, M mode in long-axis, bidimensional mode in short-axis and bidimensional mode in long-axis view of the heart. In addition the effect of weight and gender over measures was studied in the methods mentioned above. Forty adult German Shepherds without cardiovascular diseases were selected. The echocardiogram of each animal included the four described methods, according previous referenced recommendations. The effects of axis and mode as well as weight and gender were studied for each linear or derived LV measure. Weight correlated with all linear LV measures at least in one method, but not with ejection fraction (EF) and shortening fraction (SF). All LV measures of males were greater than those of females at least in one method, except for EF and SF, which did not differ between sexes. Isolated effect of the axis was observed only for LV end diastolic diameter (LVEDD), with greater values obtained from short-axis views. The combined effect of axis, gender and weight was identified in interventricular septal end diastolic thickness. There was isolated effect of mode over EF and SF, with greater measures derived from bidimensional mode methods. Weight had isolated significant positive effect over LV enddiastole posterior wall thickness in all methods, except from M mode performed in short axis, and LV end-sistolic diameter. Gender had isolated effect only over LVEDD, males showing greater values than females in bidimensional mode in short and long axis. Professionals should be aware of the possibility of erroneous interpretation when using data obtained by a different method of that used in the patient exam as reference, mainly for the values situated in inferior and superior limits of confidence intervals.

Le ventricule droit (VD) fut longtemps oublié par les cardiologues mais l'expérience a montré qu'il conditionne le pronostic des patients dans de nombreuses situations cliniques et que l'évaluation de sa fonction est un élément diagnostique majeur lorsqu'une pathologie du VD est suspectée. Après une revue des différentes méthodes d'évaluation de la fonction ventriculaire droite, cette thèse explore tout d'abord les limites des deux méthodes d'évaluation du VD les plus répandues (IRM et échographie) : Premièrement, les indices de contraction longitudinale en échographie ne permettent pas de dépister correctement les altérations de la fraction d'éjection dans la situation d'une surcharge volumétrique notamment. Deuxièmement, l'IRM en coupes petit-axe présente des difficultés importantes de délinéation de l'endocarde. Les principaux écarts de contours entre deux observateurs concernent l'infundibulum pour 40% et la valve tricuspide pour 40% également. Dans une troisième partie, nous proposons un indice géométrique simple à calculer lors d'un examen IRM et permettant de pré-sélectionner les patients nécessitant une étude précise du VD. Cet indice validé sur 340 patients réduit le temps opérateur de 35% sans entrainer d'erreur diagnostique. La dernière partie de cette thèse s'intéresse à la mesure de la vitesse tissulaire du myocarde et aux indices fonctionnels qui en dérivent. Cette mesure nécessite une haute résolution temporelle qui peut être atteinte en IRM en respiration libre au prix d'une augmentation de la durée d'acquisition / The right ventricle (RV) has been neglected for a long time by cardiologists. Only recently, it has been pointed out as yielding pronostic or diagnostic value in numerous clinical situations. This thesis, after a review of the different methods used to assess the right ventricular function, stresses the limitations of the two most used methods to assess RV function: 1) Long-axis contraction indices fail to predict ejection fraction in a volumetric overload situation. 2) Short-axis MRI relies upon a rather difficult manual contouring of the endocardium. The main variation in this contouring occurs in the infundibulum (40%) and in the basal part around the tricuspid valve (40%). Then, we propose a novel geometric indice, easy to compute during a MRI examination and aimed to select the patients needing an accurate RV study. This index was validated within 340 patients and reduced the operator time of 35% without inducing any diagnostic error. The last part of this thesis concerns tissue phase-mapping. High temporal resolution is the key point for the accuracy of myocardial velocities and can be achieved by a simple averaging during free-breathing at the expense of longer acquisitions

Introdução: O acesso ao terceiro ventrículo constitui verdadeiro desafio ao neurocirurgião. Nesse contexto, estudos anatômicos e morfométricos são úteis para estabelecer as limitações e as vantagens de determinado acesso cirúrgico. O acesso transcorioideo é versátil e promove exposição adequada da região média e posterior do terceiro ventrículo. Entretanto, a coluna do fórnice limita a exposição da região anterior do terceiro ventrículo. Há evidências de que a secção ipsilateral da coluna do fórnice tenha pouca repercussão na função cognitiva. Esta tese compara a exposição anatômica proporcionada pelo acesso transforniceal transcorioideo com o do acesso transcorioideo e realiza avaliação morfométrica de estruturas relevantes e comuns aos dois acessos. Material e métodos: A exposição anatômica proporcionada pelos acessos transcaloso transcorioideo e transcaloso transforniceal transcorioideo foram comparadas em oito cadáveres não submetidos à conservação, utilizando o sistema de neuronavegação (Artis, Brasília, Brasil), para aferir a área de trabalho, a área de exposição microcirúrgica, a exposição angular no plano longitudinal e transversal de dois alvos anatômicos (túber cinéreo e aqueduto cerebral). Adicionalmente, foram quantificados a espessura do parênquima do lobo frontal direito, a espessura do tronco do corpo caloso, o diâmetro longitudinal do forame interventricular, a distância de trabalho da superfície cortical ao túber cinéreo e a distância de trabalho da superfície cortical até o aqueduto cerebral. Os valores obtidos foram submetidos a análise de estatística utilizando o teste de Wilcoxon. Resultados: Na avaliação quantitativa, o acesso transforniceal transcorioideo proporcionou maior área de trabalho (transforniceal transcorioideo = 150,299 +/- 11,147 mm2; transcorioideo = 121,421 +/- 7,698 mm2; p < 0,05), maior área de exposição microcirúrgica (transforniceal transcorioideo = 100,920 +/- 8,764 mm2; transcorioideo = 79,944 +/- 4,954 mm2; p < 0,05), maior área de exposição angular no plano longitudinal para o túber cinéreo (transforniceal transcorioideo = 70,898 +/- 6,598 graus; transcorioideo = 63,838 +/- 5,770 graus; p < 0,05) e maior área de exposição angular no plano longitudinal para o aqueduto cerebral (transforniceal transcorioideo = 61,806 +/- 6,406 graus; transcorioideo = 54,998 +/- 5,102 graus; p < 0,05) em comparação com o acesso transcorioideo. Nenhuma diferença foi observada na exposição angular ao longo do eixo transversal para os dois alvos anatômicos (túber cinéreo e aqueduto cerebral) (p > 0,05). A espessura média do lobo frontal direito foi de 34,869 +/- 3,439 mm, a espessura do tronco caloso foi 10,085 +/- 1,172 mm, o diâmetro do forame interventricular foi de 4,628 +/- 0,474 mm, a distância da superfície cortical ao túber cinéreo foi de 69,315 +/- 4,564 mm e a distância da superfície cortical ao aqueduto cerebral foi de 75,654 +/- 4,950 mm. Na avaliação qualitativa, observamos que o acesso transforniceal transcorioideo permitiu incremento da visualização das estruturas da região anteroinferior do terceiro ventrículo. Não houve diferença quanto à exposição das estruturas da região média e posterior em ambos os acessos. Conclusões: O acesso transforniceal transcorioideo propicia maior exposição cirúrgica da região anterior do terceiro ventrículo em comparação com aquela oferecida pelo acesso transcorioideo. O estudo morfométrico estabeleceu valores médios das estruturas anatômicas comuns aos dois acessos na população estudada / Introduction: Approaches to the third ventricle constitute a formidable challenge to the neurosurgeon and, in this context, anatomical and morphometric studies are useful to establish the limitations and advantages of certain surgical approaches. The transchoroidal approach is a versatile one that promotes adequate exposure of the middle and posterior regions of the third ventricle. However, the column of fornix limits the exposure of the anterior third ventricle region. There is evidence that the ipsilateral section of the column of fornix has little effect on the cognitive function. This thesis compares the anatomical exposure using the transchoroidal transforniceal technique with the transchoroidal approach, and performs morphometric assessment of relevant structures common to both approaches. Material and methods: The anatomical exposure achieved through the transchoroidal transcallosal approach and transchoroidal transforniceal transcallosal were compared in 8 fresh cadavers using the neuronavigation system (Artis, Brasilia, Brazil), to assess the working area, microsurgical exposure area, to quantify the angular exposure in the longitudinal and cross-sectional planes to two anatomical targets (tuber cinereum and cerebral aqueduct), to measure the thickness of the right frontal lobe parenchyma, corpus callosum body thickness, longitudinal diameter of the interventricular foramen, working distance from the cortical surface to the tuber cinereum and working distance from the cortical surface to the cerebral aqueduct. The values obtained were submitted to statistical analysis using Wilcoxon\'s test. Results: In the quantitative assessment, the transchoroidal transforniceal approach provided: larger working area (transchoroidal transforniceal = 150.299 +/- 11.147 mm2; transchoroidal = 121.421 +/- 7.698 mm2; p < 0.05), larger area of microsurgical exposure (transforniceal transchoroidal = 100.920 +/- 8.764 mm2; transchoroidal = 79.944 +/- 4.954 mm2; p < 0.05), larger area of angular exposure in the longitudinal plane to the tuber cinereum (transchoroidal transforniceal = 70.898 +/- 6.598 degrees; transchoroidal = 63.838 + / - 5,770 degrees; p < 0.05) and larger area of angular exposure in the longitudinal plane to the cerebral aqueduct (transforniceal transchoroidal = 61.806 +/- 6.406 degrees; transchoroidal = 54.998 +/- 5.102 degrees; p < 0.05) when compared to the transchoroidal approach. No differences were observed in the angular exposure along the cross-sectional axis for both anatomical targets (tuber cinereum and cerebral aqueduct) (p > 0.05). The mean thickness of the right frontal lobe was 34.869 +/- 3.439 mm, the thickness of the corpus callosum body was 10.085 +/- 1.172 mm, the diameter of the interventricular foramen was 4,628 +/- 0,474 mm, the distance from the cortical surface to the tuber cinereum was 69.315 +/- 4.564 mm, and the distance from the cortical surface to the cerebral aqueduct was 75.654 +/- 4.950 mm. In the qualitative assessment, we observed that the transforniceal transchoroidal approach allowed better visualization of the structures in the anterior third ventricle region. There was no difference regarding exposure of structures in the middle and posterior regions with both access. Conclusions: The transforniceal transchoroidal approach provides greater surgical exposure of the anterior third ventricle region than that obtained with the transchoroidal approach. The morphometric study established mean values of anatomical structures that are common to both approaches in the assessed population

La fonction du ventricule droit est un déterminant majeur de la capacité fonctionnelle et du pronostic dans l’hypertension pulmonaire. La survenue dans ce contexte d’une insuffisance cardiaque droite requérant un support inotrope est associée à un taux de mortalité supérieur à 40%. Les déterminants cellulaires et moléculaires du découplage entre le coeur droit et la circulation artérielle pulmonaire sont méconnus, d’autant qu’il existe une grande hétérogénéité fonctionnelle parmi les patients soumis au même niveau de résistances vasculaires pulmonaires.Dans une première étude expérimentale, nous avons mis évidence à partir d’un modèle porcin d’hypertension pulmonaire chronique que les indices fonctionnels systoliques du ventricule droit mesurés en échocardiographie sont davantage corrélés au couplage ventriculo-artériel qu’à la performance contractile propre du ventricule droit. La réponse du ventricule droit à l’exercice ou à un stress pharmacologique a été peu documentée jusqu’à présent dans l’hypertension pulmonaire. Apartir de notre modèle porcin, nous avons montré que l’altération de la réserve contractile du ventricule droit est fortement associée au découplage ventriculo-artériel. La réserve contractile pourrait être un marqueur sensible et précoce de dysfonction ventriculaire droite. Dans une troisième étude, nous montrons la relation forte entre le couplage ventriculo-artériel et la plasticitéhémodynamique, fonctionnelle et moléculaire du ventricule droit dans un contexte de surcharge de pression chronique. Les variations d’expression de l’isoforme β de la chaîne légère de la myosine cardiaque pourraient déterminer l’efficacité du travail cardiaque droit. Nous avons par ailleurs constaté expérimentalement chez le rat que le remodelage géométrique et fonctionnel du ventricule droit en condition de surcharge barométrique chronique est associé à une infiltration macrophagique dumuscle cardiaque droit.Nos résultats physiopathologiques pourraient permettre une meilleure stratification des patients souffrant d’hypertension pulmonaire chronique. Ces mécanismes pourraient par ailleurs constituer autant de cibles thérapeutiques pour optimiser la fonction cardiaque droite lorsque la postcharge du ventricule droit n’est pas complètement corrigée, d’autant que les thérapies vaso-actives pulmonaires usuelles auraient des effets directs controversés sur le remodelage du ventricule droit. / Right ventricular function is a major determinant of functional capacity and prognosis in pulmonary hypertension. Right heart failure related to pulmonary hypertension is associated with a mortality rate up to 40% when inotrope support is necessary. Cellular and molecular determinants of right ventricular-pulmonary arterial coupling are misunderstood, while a wide functional range is remarkable among patients sharing the same degree of pulmonary vascular resistance.In a first experimental study, we showed from a porcine model of chronic pulmonary hypertension that usual non-invasive indices of right ventricular function are rather associated with ventricular-arterial coupling than with contractility. Right ventricular response to exercise or to pharmacological stress has been poorly reported in pulmonary hypertension. In our piglet model, we showed that impairment of right ventricular contractile reserve is strongly associated with ventricular-arterial uncoupling. Rightventricular reserve might be a sensitive marker of early ventricular dysfunction. In a third study, we highlighted that a strong relationship between ventricular-arterial coupling and functional and molecular plasticity of the pressure overloaded right ventricle. Gene expression of the beta-myosin heavy chain may be related to right heart efficiency. We also oberved experimentally in rats that structural and functional remodeling of the pressure overloaded right ventricle is associated withmacrophagic infiltration in the myocardium.Our pathophysiologic results could improve patient’s stratification in chronic pulmonary hypertension.These mechanisms may represent innovative targeted therapies to improve right ventricular function despite persistent elevated afterload.