Sector-Wise Golden Angle (SWIG) is a novel approach that was developed to address the limitations associated with Golden Angle radial imaging, commonly used for high temporal resolution flow measurements. Golden angle radial imaging is a time-efficient method that effectively reduces motion sensitivity. However, binned or retrospectively gated imaging where multiple heartbeats are utilized to acquire a single time series may lead to uneven coverage of k- space, ultimately resulting in poor image quality. In contrast, SWIG restricts the radial profiles to a sector of k-space per heartbeat, ensuring even distributions of spokes during retrospectively gated acquisitions. One drawback of SWIG is the loss of ability to reconstruct real-time images. The combination of sorted and unsorted acquisition simultaneously holds significant potential and could be applied in various domains. The goal of the thesis work was to design a trajectory that combines radial and spiral k-space sampling, enabling hybrid real-time and retrospectively gated imaging. The objective was to obtain an image series with comparable quality to a SWIG readout while retaining the ability to reconstruct a low-resolution real-time image series from the same data. To evaluate the hybrid trajectory, the numerical phantom XCAT was used to generate synthetic MRI images. Binned images were sampled using a hybrid-SWIG method, yielding similar image quality to a conventional SWIG image series, with the added benefit of being able to reconstruct a low-resolution real-time image series. Although the current method was only evaluated in a numerical phantom and may require additional adjustment to be suitable for a real MRI scanner, the results show that it is possible to combine radial and spiral imaging in a single readout.

A cardiomiopatia hipertrófica (CMH) é uma doença cardíaca genética e se caracteriza como a principal causadora de morte súbita em jovens, com apresentação clínica variável, desde assintomáticos a morte súbita, o que dificulta sua estratificação de risco. Tanto a ressonância magnética cardiovascular (RMC) como a tomografia computadorizada com múltiplos detectores (TCMD) mostraram-se capazes de avaliar a fibrose miocárdica, que é frequentemente encontrada nos casos de CMH. Os objetivos desta tese são: avaliar a distribuição e a correlação entre as áreas de hipertrofia e fibrose miocárdica pela RMC em pacientes com CMH; comparar a avaliação da fibrose miocárdica pela TCMD com a avaliação da fibrose miocárdica pela RMC; avaliar a fibrose miocárdica pela TCMD em pacientes com CMH portadores de cardiodesfibriladores e correlacionar a fibrose miocárdica pela TCMD com as arritmias ventriculares com terapia apropriada pelo CDI. Foram selecionados 145 pacientes com CMH, dos quais 13 apresentaram critérios de exclusão, sendo, portanto, incluídos 132 pacientes em seguimento ambulatorial, que assinaram termo de consentimento livre e esclarecido. Destes, 91 pacientes foram submetidos à RMC para avaliação das características morfofuncionais do coração, incluindo a caracterização da fibrose miocárdica. Outros 15 pacientes foram submetidos tanto à TCMD quanto à RMC para avaliação e comparação da fibrose miocárdica por ambos os métodos. Finalmente, 26 pacientes hipertróficos portadores de CDI foram submetidos somente à TCMD para a avaliação da fibrose miocárdica e seguimento. Entre os 91 pacientes submetidos à RMC, a idade média foi de 37,9±17 anos, dos quais 58% eram homens. A média da espessura máxima da maior parede hipertrofiada do VE foi de 24,2±6,3mm e a média da FEVE, de 73,3±13,3%. A fibrose miocárdica foi observada em 76,9% dos 91 pacientes com uma média da massa de fibrose indexada pela superfície corpórea de 8,1±11,0g/m2. Dos 1547 segmentos miocárdicos pertencentes aos 91 pacientes, 18,9% (293) apresentaram fibrose miocárdica. Destes, 35,2% dos segmentos com fibrose apresentavam espessura miocárdica normal. Por outro lado, 58,6% dos segmentos hipertrofiados não apresentavam fibrose miocárdica. Além disso, não foi observada correlação significativa entre os segmentos hipertrofiados e os segmentos com fibrose miocárdica pela regressão linear. (r = 0,13 p = 0,21). Adicionalmente, a análise por paciente demonstrou que 65,8% dos indivíduos não apresentavam concordância significativa (Kappa < 0,40, p NS) entre a hipertrofia e a fibrose miocárdica, enquanto 34,2% apresentavam concordância moderada, boa ou excelente entre a hipertrofia e a fibrose miocárdica (Kappa > 0,40, p<0,001). A comparação da análise do porcentual da fibrose miocárdica no grupo de 15 pacientes submetidos tanto a TCMD quanto a RMC, demonstrou boa correlação com r = 0,77 e p =0,0001 e média das diferenças de 0,99 gramas. A análise da fibrose miocárdica pela TCMD dos 26 pacientes com CMH e portadores de desfibriladores implantáveis há mais de um ano demonstrou que a fibrose miocárdica estava presente em 96,1% desta população de alto risco, com média de 20,5 ±15,8 gramas de fibrose. Em um segmento médio de 38,5±25,5 meses, 50% destes pacientes apresentaram choques apropriados secundários - na maioria à fibrilação ventricular (12/13 eventos). Naqueles que receberam choques apropriados, a massa de fibrose era significativamente maior do que naqueles que não se observaram o registro das arritmias (29,10±19,13g vs 13,57±8,31g, p=0,01). Utilizando 18 gramas de fibrose como ponto de corte, a chance de registro de FV/TV com terapia apropriada pelo CDI foi de 75%. O seguimento dos pacientes demonstrou que massa de fibrose miocárdica acima de 18 gramas apresentava taxa de arritmias ventriculares com terapia apropriada pelos desfibriladores significativamente maior (p=0,02). Na análise multivariada, a massa de fibrose miocárdica foi a única a se correlacionar independentemente com as arritmias ventriculares adequadamente tratadas pelos CDIs. Concluímos que a apresentação das áreas de hipertrofia e fibrose miocárdica é heterogênea e que a correlação entre elas nas imagens de RMC é variável, não sendo significativa na maioria dos pacientes. Nossos dados de validação da TCMD permitem concluir que quando a RMC não pode ser utilizada, a tomografia pode ser uma alternativa adequada. A análise da fibrose miocárdica em pacientes com CMH e CDI demonstrou associação significativa e independente entre a magnitude da fibrose miocárdica e terapia apropriada pelos desfibriladores / Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder leading cause of sudden death in young people with extremely variable presentation, from asymptomatic to sudden death as first symptom, leads to challenging risk stratification. Recently, both cardiovascular magnetic resonance (CMR) and multidetector computed tomography (MDCT) were able to assess myocardial fibrosis (MF) often found in cases of HCM. Our objectives were to evaluate the distribution and correlation of myocardial hypertrophy (MH) and myocardial fibrosis by CMR in patients with HCM; to compare and validate the assessment of myocardial fibrosis by MDCT and CMR and to evaluate the correlation between myocardial fibrosis by MDCT and ventricular arrhythmias appropriately treated by defibrillators, due to contraindications to CMR in this group. 145 HCM patients were selected with 13 having exclusion criteria. Then 132 outpatients were included and signed informed consent for this study. First, 91 patients were submitted to CMR to evaluate the morphofunctional characteristics of the heart including myocardial fibrosis; Second, 15 patients were submitted to both MDCT and CMR in order to evaluate myocardial fibrosis by both methods, and finally 26 HCM patients with implantable cardiac defibrillator (ICD) were submitted to MDCT, for assessment MF. Among 91 patients submitted to CMR the mean age was 37.9 ± 17 years old, and 58% were men. The LV maximum end diastolic wall thickness was 24.2 ± 6.3mm and LVEF mean was 73.3% ± 13.3. MF was evident in 76.9% of patients with a mean fibrosis mass index of 8.1±11.0g/m2. Of all the 1547 myocardial segments from 91 HCM patient, 35.2% of segments with MF occurred in segments without MH, 58.6% of MH segments had no signs of MF. Linear regression showed no significant correlation between number of segments with MH and MF (r = 0.13, p = 0.21). A per patient Kappa analysis showed no significant agreement (Kappa0.40, p ns) between MH and MF in 65.8% of the population and the remaining 34.2% of this population showed a significant agreement between MH and MF (kappa > 0.40, p < 0.001). The analysis of MF% in the group of 15 HCM patients submitted by both MDCT and MR showed a good correlation by linear regression between the two methods with r = 0.77 and p = 0.0001 with mean difference of 0.99g. The MF analysis by TCMD in 26 HCM patients with ICD, clinically indicated, for at least one year demonstrated that MF was present in 96.1% of patients with a mean fibrosis mass of 20.5±15.8g. During the mean follow-up of 38.5±25.5 months, 50% of these patients present appropriated shocks due to ventricular fibrillation in most of cases (12/13 registered events). Patients with appropriate ICD shocks had significantly greater MF mass than those without (29.10±19.13g vs 13.57±8.31g, p=0.01). The best MF mass cut off was 18g, with an accuracy of 0.75 for predicting ICD firing. Patients with MF mass 18g had a significantly higher event rate in the follow up (p=0.02). MF mass was independently associated with ventricular tachycardia/fibrillation on ICD-stored electrograms by multivariate analysis. We conclude that the presentation of myocardial hypertrophy and fibrosis areas is heterogeneous and the correlation between MH and MF is variable and non significant in the most of the patients in CMR images. The validation data of MF techniques showed that in cases where CMR can not be used, MDCT may be a good alternative to assessment of fibrosis. The MF analysis in HCM patients with ICD showed a significant and independent association between MF extent and VF / VT appropriated therapy by ICDs

Dilated cardiomyopathy (DCM) is the second leading cause of heart failure. The pathophysiology in DCM is still poorly understood, partly because of currently limited research tools. We investigated whether cardiovascular magnetic resonance (CMR), using novel imaging techniques, could be used for in vivo assessment of some key pathophysiological mechanisms related to DCM. In addition, we evaluated whether the pathological findings on CMR would predict clinically relevant functional and morphological improvement of the left ventricular (LV) function - the LV reverse remodeling (LVRR). CMR together with endomyocardial biopsy, echocardiography, cardiopulmonary exercise testing and a thorough assessment of cardiac biomarkers was performed in 44 patients with new-onset DCM (<6 months of duration). The imaging was repeated after 12 months of clinical follow-up. Endomyocardial biopsy revealed myocardial inflammation in 34 % of the patients. LVRR at 12 months occurred in 45 % of the patients. Presence of late gadolinium enhancement (LGE) in the left ventricle was a sensitive but unspecific sign of myocardial inflammation because it was also a feature of hemodynamic stress related to the heart failure. The baseline extent of LGE was an independent predictor of future LVRR and also a predictor of adverse clinical...

A cardiomiopatia hipertrófica (CMH) é uma doença cardíaca genética e se caracteriza como a principal causadora de morte súbita em jovens, com apresentação clínica variável, desde assintomáticos a morte súbita, o que dificulta sua estratificação de risco. Tanto a ressonância magnética cardiovascular (RMC) como a tomografia computadorizada com múltiplos detectores (TCMD) mostraram-se capazes de avaliar a fibrose miocárdica, que é frequentemente encontrada nos casos de CMH. Os objetivos desta tese são: avaliar a distribuição e a correlação entre as áreas de hipertrofia e fibrose miocárdica pela RMC em pacientes com CMH; comparar a avaliação da fibrose miocárdica pela TCMD com a avaliação da fibrose miocárdica pela RMC; avaliar a fibrose miocárdica pela TCMD em pacientes com CMH portadores de cardiodesfibriladores e correlacionar a fibrose miocárdica pela TCMD com as arritmias ventriculares com terapia apropriada pelo CDI. Foram selecionados 145 pacientes com CMH, dos quais 13 apresentaram critérios de exclusão, sendo, portanto, incluídos 132 pacientes em seguimento ambulatorial, que assinaram termo de consentimento livre e esclarecido. Destes, 91 pacientes foram submetidos à RMC para avaliação das características morfofuncionais do coração, incluindo a caracterização da fibrose miocárdica. Outros 15 pacientes foram submetidos tanto à TCMD quanto à RMC para avaliação e comparação da fibrose miocárdica por ambos os métodos. Finalmente, 26 pacientes hipertróficos portadores de CDI foram submetidos somente à TCMD para a avaliação da fibrose miocárdica e seguimento. Entre os 91 pacientes submetidos à RMC, a idade média foi de 37,9±17 anos, dos quais 58% eram homens. A média da espessura máxima da maior parede hipertrofiada do VE foi de 24,2±6,3mm e a média da FEVE, de 73,3±13,3%. A fibrose miocárdica foi observada em 76,9% dos 91 pacientes com uma média da massa de fibrose indexada pela superfície corpórea de 8,1±11,0g/m2. Dos 1547 segmentos miocárdicos pertencentes aos 91 pacientes, 18,9% (293) apresentaram fibrose miocárdica. Destes, 35,2% dos segmentos com fibrose apresentavam espessura miocárdica normal. Por outro lado, 58,6% dos segmentos hipertrofiados não apresentavam fibrose miocárdica. Além disso, não foi observada correlação significativa entre os segmentos hipertrofiados e os segmentos com fibrose miocárdica pela regressão linear. (r = 0,13 p = 0,21). Adicionalmente, a análise por paciente demonstrou que 65,8% dos indivíduos não apresentavam concordância significativa (Kappa < 0,40, p NS) entre a hipertrofia e a fibrose miocárdica, enquanto 34,2% apresentavam concordância moderada, boa ou excelente entre a hipertrofia e a fibrose miocárdica (Kappa > 0,40, p<0,001). A comparação da análise do porcentual da fibrose miocárdica no grupo de 15 pacientes submetidos tanto a TCMD quanto a RMC, demonstrou boa correlação com r = 0,77 e p =0,0001 e média das diferenças de 0,99 gramas. A análise da fibrose miocárdica pela TCMD dos 26 pacientes com CMH e portadores de desfibriladores implantáveis há mais de um ano demonstrou que a fibrose miocárdica estava presente em 96,1% desta população de alto risco, com média de 20,5 ±15,8 gramas de fibrose. Em um segmento médio de 38,5±25,5 meses, 50% destes pacientes apresentaram choques apropriados secundários - na maioria à fibrilação ventricular (12/13 eventos). Naqueles que receberam choques apropriados, a massa de fibrose era significativamente maior do que naqueles que não se observaram o registro das arritmias (29,10±19,13g vs 13,57±8,31g, p=0,01). Utilizando 18 gramas de fibrose como ponto de corte, a chance de registro de FV/TV com terapia apropriada pelo CDI foi de 75%. O seguimento dos pacientes demonstrou que massa de fibrose miocárdica acima de 18 gramas apresentava taxa de arritmias ventriculares com terapia apropriada pelos desfibriladores significativamente maior (p=0,02). Na análise multivariada, a massa de fibrose miocárdica foi a única a se correlacionar independentemente com as arritmias ventriculares adequadamente tratadas pelos CDIs. Concluímos que a apresentação das áreas de hipertrofia e fibrose miocárdica é heterogênea e que a correlação entre elas nas imagens de RMC é variável, não sendo significativa na maioria dos pacientes. Nossos dados de validação da TCMD permitem concluir que quando a RMC não pode ser utilizada, a tomografia pode ser uma alternativa adequada. A análise da fibrose miocárdica em pacientes com CMH e CDI demonstrou associação significativa e independente entre a magnitude da fibrose miocárdica e terapia apropriada pelos desfibriladores / Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder leading cause of sudden death in young people with extremely variable presentation, from asymptomatic to sudden death as first symptom, leads to challenging risk stratification. Recently, both cardiovascular magnetic resonance (CMR) and multidetector computed tomography (MDCT) were able to assess myocardial fibrosis (MF) often found in cases of HCM. Our objectives were to evaluate the distribution and correlation of myocardial hypertrophy (MH) and myocardial fibrosis by CMR in patients with HCM; to compare and validate the assessment of myocardial fibrosis by MDCT and CMR and to evaluate the correlation between myocardial fibrosis by MDCT and ventricular arrhythmias appropriately treated by defibrillators, due to contraindications to CMR in this group. 145 HCM patients were selected with 13 having exclusion criteria. Then 132 outpatients were included and signed informed consent for this study. First, 91 patients were submitted to CMR to evaluate the morphofunctional characteristics of the heart including myocardial fibrosis; Second, 15 patients were submitted to both MDCT and CMR in order to evaluate myocardial fibrosis by both methods, and finally 26 HCM patients with implantable cardiac defibrillator (ICD) were submitted to MDCT, for assessment MF. Among 91 patients submitted to CMR the mean age was 37.9 ± 17 years old, and 58% were men. The LV maximum end diastolic wall thickness was 24.2 ± 6.3mm and LVEF mean was 73.3% ± 13.3. MF was evident in 76.9% of patients with a mean fibrosis mass index of 8.1±11.0g/m2. Of all the 1547 myocardial segments from 91 HCM patient, 35.2% of segments with MF occurred in segments without MH, 58.6% of MH segments had no signs of MF. Linear regression showed no significant correlation between number of segments with MH and MF (r = 0.13, p = 0.21). A per patient Kappa analysis showed no significant agreement (Kappa0.40, p ns) between MH and MF in 65.8% of the population and the remaining 34.2% of this population showed a significant agreement between MH and MF (kappa > 0.40, p < 0.001). The analysis of MF% in the group of 15 HCM patients submitted by both MDCT and MR showed a good correlation by linear regression between the two methods with r = 0.77 and p = 0.0001 with mean difference of 0.99g. The MF analysis by TCMD in 26 HCM patients with ICD, clinically indicated, for at least one year demonstrated that MF was present in 96.1% of patients with a mean fibrosis mass of 20.5±15.8g. During the mean follow-up of 38.5±25.5 months, 50% of these patients present appropriated shocks due to ventricular fibrillation in most of cases (12/13 registered events). Patients with appropriate ICD shocks had significantly greater MF mass than those without (29.10±19.13g vs 13.57±8.31g, p=0.01). The best MF mass cut off was 18g, with an accuracy of 0.75 for predicting ICD firing. Patients with MF mass 18g had a significantly higher event rate in the follow up (p=0.02). MF mass was independently associated with ventricular tachycardia/fibrillation on ICD-stored electrograms by multivariate analysis. We conclude that the presentation of myocardial hypertrophy and fibrosis areas is heterogeneous and the correlation between MH and MF is variable and non significant in the most of the patients in CMR images. The validation data of MF techniques showed that in cases where CMR can not be used, MDCT may be a good alternative to assessment of fibrosis. The MF analysis in HCM patients with ICD showed a significant and independent association between MF extent and VF / VT appropriated therapy by ICDs

Dilated cardiomyopathy (DCM) is the second leading cause of heart failure. The pathophysiology in DCM is still poorly understood, partly because of currently limited research tools. We investigated whether cardiovascular magnetic resonance (CMR), using novel imaging techniques, could be used for in vivo assessment of some key pathophysiological mechanisms related to DCM. In addition, we evaluated whether the pathological findings on CMR would predict clinically relevant functional and morphological improvement of the left ventricular (LV) function - the LV reverse remodeling (LVRR). CMR together with endomyocardial biopsy, echocardiography, cardiopulmonary exercise testing and a thorough assessment of cardiac biomarkers was performed in 44 patients with new-onset DCM (<6 months of duration). The imaging was repeated after 12 months of clinical follow-up. Endomyocardial biopsy revealed myocardial inflammation in 34 % of the patients. LVRR at 12 months occurred in 45 % of the patients. Presence of late gadolinium enhancement (LGE) in the left ventricle was a sensitive but unspecific sign of myocardial inflammation because it was also a feature of hemodynamic stress related to the heart failure. The baseline extent of LGE was an independent predictor of future LVRR and also a predictor of adverse clinical...

Aorte est l'artère qui amortit et conduit le flux sanguin éjecté par le cœur en flux continu vers la périphérie. Avec l’âge, l'élasticité aortique diminue en association avec des altérations fonctionnelles et hémodynamiques de l’aorte et du cœur. Alors que l'hémodynamique artérielle a été largement étudiée par l'analyse des courbes de pression, les modifications de l’onde de débit aortique n’ont été que très peu explorées. L’imagerie IRM, couplée à une segmentation appropriée, permet une évaluation non-invasive et précise du débit sanguin aortique. Cette thèse combine ce débit mesuré en IRM avec les pressions tonométriques afin de proposer des indices quantitatives de rigidité artérielle. Ainsi, ce travail comprend: Une nouvelle approche, basée sur les ondelettes, pour estimer le temps de transit entre les ondes de flux provenant de deux sites aortiques. Ce dernier a permis de calculer la vitesse de l'onde de pouls dans la crosse, qui s’est avérée être un marqueur fort de la rigidité et de l’âge. Une analyse d'impédance aortique dans le domaine fréquentiel pour quantifier la charge pulsatile et les réflexions qui augmentent la charge exercée sur le cœur. Une quantification de la forme de l'onde de débit aortique, dont l’association avec les changements géométriques du cœur a été montrée. Une cartographie des pressions intra-aortiques absolues en utilisant les équations de Navier-Stokes. Ces nouveaux indices ont été testés sur 70 sujets sains et leur complémentarité en termes de caractérisation de l’âge et du couplage entre l'aorte et le cœur a été montrée. De futures études sur l'hypertension artérielle permettront de démontrer l'utilité clinique de nos indices. / Aorta is the artery which immediately accommodates the blood flow ejected from the heart. It buffers blood’s pulsatile momentum and conducts it smoothly towards periphery. With physiological aging, aortic elasticity diminishes significantly in association with aortic or cardiac functional and hemodynamic alterations. While aortic hemodynamics were widely studied through pressure curves analysis, proximal aorta flow patterns were only little investigated. Recent developments of cardiovascular magnetic resonance imaging (MRI) and image segmentation tools, enable an accurate non-invasive evaluation of proximal aortic blood flow. This thesis combined MRI with central pressure measurements by applanation tonometry to propose flow-indices of arterial stiffness. Indeed our work proposed: A new wavelet-based method, which enables temporal localization of signal frequencies to estimate transit-time between flow waves from two aortic sites, in order to derive aortic arch pulse wave velocity, which is a strong marker of stiffening and aging. An aortic impedance analysis in frequency domain to provide indices which reflect changes in aortic pulsatile load and wave reflection, which augments the load on the heart Quantitative flow-morphology indices which were shown to be associated with age-related changes in left heart geometry. Absolute intra-aortic pressure mapping using the Navier-Stokes equations. These new indices have been tested on 70 healthy volunteers and findings indicated their complementary nature in characterizing aging and aortic-heart coupling. Further investigations in the context of hypertension will prove the clinical usefulness of our indices.

<p>  </p> <p>Heart disease is the leading cause of death for individuals with Duchenne muscular dystrophy (DMD). DMD is a devastating and progressive neuromuscular disease with no known cure. This X-linked genetic disorder affects nearly 1 in 5000 boys and manifests as debilitating muscle weakness and progressive cardiomyopathy (CM). While CM in some individuals with DMD progresses rapidly and fatally in their teenage years, others can live relatively symptom-free into their thirties or forties. Early identification and treatment can improve quality and length of life, but currently, there are no standard imaging biomarkers that can detect early onset or rapidly progressing DMD CM. Addressing this gap, we describe here a novel cardiac image analysis paradigm using 4D cardiac magnetic resonance imaging (CMR) to map left-ventricular kinematics comprehensively in DMD CM. The primary goal of this dissertation work is to introduce novel imaging biomarkers and computational methods to enable earlier diagnosis and precise prognosis for cardiac function in DMD. Central to this goal, we identified myocardial strain biomarkers that predict the early onset and rapid progression of cardiac disease in vulnerable patients. These findings bridge clinical gaps and pave the way for multi-center studies to characterize DMD CM progression and assessment of individual patient risk profiles for improved treatment and outcomes in DMD.</p>

No description available.

L’IRM cardiaque a une capacité unique d’étudier le remodelage ventriculaire gauche (VG) après infarctus du myocarde. Les objectifs principaux de ce travail étaient de caractériser le tissue de l’infarctus par IRM et d’évaluer les facteurs associés au remodelage du VG. Nous avons étudié prospectivement 114 patients présentant un premier infarctus du myocarde avec sus-décalage du segment ST et ayant subi une angioplastie primaire. Des IRM cardiaques ont été réalisées dans les 2 à 4 jours et à 6 mois suivant la revascularisation. Premièrement, nous avons réalisé une analyse comparative de différentes méthodes de segmentation de l’infarctus sur l’imagerie de rehaussement tardive (RT). Deuxièmement, nous avons étudié l’évolution des différentes composantes de la zone RT au cours des six mois, et observé que la réduction de la zone RT (33,8%) était représentée par l’extension de la zone grise initiale. Troisièmement, nous avons évalué le rôle clinique de la zone grise. Elle s’est révélée protectrice vis-à-vis du remodelage délétère. Quatrièmement, nous avons étudié l’influence de l’obstruction microvasculaire (OMV) sur le remodelage local du VG. Différents motifs ont été observés entre les patients atteints de l’OMV et ceux ne présentant pas d’OMV: un rétrécissement uniforme à travers le VG chez les patients sans OMV lorsque les sujets avec OMV présentaient une dilatation globale significative, ainsi qu’une dilatation plus importante dans les régions atteint d’OMV / Cardiac MRI (CMR) has the unique ability to study left ventricular remodeling after myocardial infarction. The main objectives of this work were to characterize infarct tissue by CMR and to evaluate factors associated with LV remodeling. We prospectively studied 114 patients with a first ST-segment elevation myocardial infarction (STEMI) undergoing primary angioplasty. CMR was performed within 2-4 days and at 6 months after the revascularization. First, we compared different methods for the segmentation of myocardial infarcts on late gadolinium enhancement (LGE) imaging. Second, we described the evolution of different components of LGE area during 6 months. We found that the decrease of LGE area (33.8%) matched the extent of initial gray zone. Third, we studied the clinical role of gray zone. The gray zone was found to be a protective factor for adverse remodeling. Fourth, we studied the influence of microvascular obstruction (MVO) on local LV remodeling and observed distinct remodeling patterns in patients with and without MVO: equally-distributed shrinkage throughout the LV cavity in patients without MVO whereas significant dilation occurring in those with MVO, tending to be greater in myocardial regions containing MVO

The main goal of this dissertation was to assess prospectively the value of two cardiovascular magnetic resonance methodises (the transmural extent of an late gadolinium enhancement and the contractile reserve during low dose dobutamine administration) as predictors of left ventricular segmental and global functional recovery in patients with left ventricular systolic dysfunction undergoing surgical or percutaneous revascularisation. Taking into account previous studies, revascularisation of the viable myocardium results in an improvement of patient’s symptoms and prognosis. This finding emphasized the need for and importance of noninvasive tests to quantify the amount of viable myocardium in patients with left ventricular dysfunction in order to define the optimal management strategy. On the basis of the research described in the dissertation, the diagnostic value of different cardiovascular magnetic resonance based viability prediction methods was assessed. The superiority of combined viability prediction model incorporating an late gadolinium enhancement and the contractile reserve during low dose dobutamine administration was confirmed. The optimal predictors of the significant improvement of left ventricular ejection fraction were found: the percentage of viable segments from all dysfunctional and revascularised segments in a patient and the absolute value of left ventricular ejection fraction measured during low dose dobutamine administration. On the basis of the... [to full text] / Disertacijoje nagrinėta dviejų magnetinio rezonanso metodikų (vėlyvojo kontrastinės medžiagos kaupimo transmuralumo bei mažų dobutamino dozių sukeliamo miokardo kontraktilinio rezervo) bei šių metodikų derinio vertė, prognozuojant bendrosios bei segmentinės kairiojo skilvelio funkcijos atsistatymą po revaskuliarizacijos (perkutaninės vainikinių arterijų intervencijos ar vainikinių arterijų apeinamųjų jungčių suformavimo operacijos), pacientams, turintiems išeminės kilmės kairiojo skilvelio sistolinę disfunkciją. Kadangi yra nustatyta, jog sėkminga gyvybingo miokardo revaskuliarizacija pagerina kairiojo skilvelio sistolinę disfunkciją turinčių pacientų simptomus bei prognozę, todėl gyvybingo miokardo nustatymas yra svarbus, siekiant parinkti optimalią tokių pacientų gydymo taktiką. Disertacijoje aprašomo tyrimo pagalba buvo nustatyta širdies magnetinio rezonanso vertė, prognozuojant miokardo bendrosios bei segmentinės kontrakcijos atsistatymą bei pagrįsta vėlyvojo kontrastinės medžiagos kaupimo transmuralumo bei mažų dobutamino dozių sukeliamo kontraktilinio rezervo nustatymo metodikų derinimo nauda. Disertacijoje aptarti optimalūs reikšmingo bendrosios kairiojo skilvelio sistolinės funkcijos pagerėjimo prognostiniai rodikliai: gyvybingų segmentų procentas nuo visų išeityje disfunkcinių bei revaskuliarizuotų paciento segmentų bei absoliuti kairiojo skilvelio išstūmimo frakcija, išmatuota mažų dobutamino dozių skyrimo metu. Disertacijos rezultatų pagrindu buvo sukurtas... [toliau žr. visą tekstą]