L’hypertension artérielle pulmonaire (HTAP) est une maladie caractérisée par une obstruction des artères pulmonaires de petit calibre aboutissant, à terme, à une défaillance cardiaque droite. L’évolution de cette maladie est parfois émaillée d’épisodes de dégradation de l’état fonctionnel des patients, nécessitant une admission en unité de soins intensifs pour surveillance cardioscopique et administration de médicaments inotropes et/ou vasopresseurs. Peu d’éléments permettent à ce jour de guider les praticiens dans la prise en charge de ces patients et la physiopathologie de ces épisodes est assez peu connue.Dans un premier temps, nous avons retrouvé une mortalité de 41% en réanimation et testé certains facteurs pronostiques cliniques et biologiques simples issus de la pratique quotidienne dans une cohorte propective de patients avec une prise en charge standardisée. Nous avons identifié comme facteurs pronostiques la pression artérielle systémique, la natrémie, la créatininémie, la valeur de la C-reactive Proteine. Nous avons retrouvé une influence de ces épisodes sur l’évolution à moyen terme de ces épisodes. Dans un second temps nous avons testé la valeur pronostique des indices temporels de fonctionnement du ventricule gauche, suggérée par les études en imagerie par résonnance magnétique. Nous avons utilisé pour cela la tonométrie d’aplanation, outil original et non invasif. Nous avons retrouvé que la valeur de la durée d’éjection du ventricule gauche est associée au pronostic. Dans une troisième partie nous avons mesuré les conséquences et la valeur pronostique de l’épuration extra rénale en contexte d’ insuffisance rénale menaçante chez ces patients. Dans une étude rétrospective, nous avons observé 68 séances d’épuration extra-rénale continue ou discontinue. Ces séances se sont compliquées d’hypotension artérielle dans environ 50% des cas. La très haute mortalité en réanimation et à 3 mois, respectivement de 47% et 73%, soulève la question de la place de l’assistance circulatoire et de la transplantation urgente chez ces patients. Ces données soulignent la sévérité à court terme des épisodes aigus d’aggravation chez les patients porteurs d’HTAP. De plus amples données sont nécessaires pour améliorer la prise en charge de ces patients et organiser dans le meilleur délai la mise en place de thérapeutiques exceptionnelles comme l’assistance circulatoire et la transplantation pulmonaire ou cardio-pulmonaire. / Pulmonary arterial hypertension ( PAH) is a disease characterized by an obstruction of the small pulmonary arteries leading ultimately to right heart failure. The evolution of this disease is sometimes punctuated by episodes of deterioration of the functional status of patients requiring admission to intensive care unit for monitoring and administration of inotropic drugs and / or vasopressors. Few evidence to date are available to guide physicians in the care of these patients and the pathophysiology of these episodes is still elusive.In a first part, we found a mortality of 41% in the intensive care unit (ICU) and tested some simple clinical and biological prognostic factors from the daily practice in a prospective cohort of patients with a standardized management. We have identified systemic blood pressure, serum sodium, serum creatinine, serum C -reactive Protein as prognostic factors. We found an influence of these events on the medium-term evolution of the patients.In a second step we tested the prognostic value of time derived indices of left ventricular function, variables suggested by magnetic resonance imaging studies. In this purpose, we used aplanation tonometry, an original and non-invasive tool. We found that the value of the left ventricular ejection time was associated with in ICU prognosis.In the third part we measured the impact and prognostic value of renal replacement therapy in case of threatening kidney failure in these patients. In a retrospective study, we observed 68 sessions of renal replacement therapy, continuous hemofiltration and intermittent hemodialysis. These sessions were complicated by hypotension in 50 % of cases. The high in ICU mortality and three months mortilty, respectively 47% and 73%, raises the question of the role of extracorporeal life support and urgent transplantation in these patients.These data underscore the severity of acute worsening in patients with PAH. More data are needed to improve the management of these patients and determine the best timing of exceptional treatment such as circulatory support and pulmonary or cardiopulmonary transplantation.

A hipertensão arterial pulmonar (HAP) é caracterizada pelo aumento da resistência vascular pulmonar (RVP). Em decorrência, há elevação da pós-carga imposta ao ventrículo direito (VD) e hipertrofia. Assim, com aumento de consumo de O2 pelo miocárdio, é provável que o estresse oxidativo esteja participando do desenvolvimento e progressão desta doença. Sabe-se que o bloqueio beta-adrenérgico diminui a mortalidade de pacientes com insuficiência cardíaca à esquerda, porém pouquíssimas pesquisas referem sua utilização na insuficiência cardíaca à direita. O bucindolol é um beta-bloqueador que atua nos receptores β1, β2, α1 e com propriedade simpatolítica. O objetivo deste estudo foi testar a hipótese de que o tratamento com bucindolol poderia reduzir a hipertrofia do VD e melhorar a função sistólica e diastólica do miocárdio. Foram utilizados ratos Wistar machos pesando 130±10 gramas divididos em quatro grupos (n=7-10/grupo): monocrotalina sem bucindolol (MCT SEM BCD), monocrotalina bucindolol (MCT+BCD), controle sem bucindolol (CTR SEM BCD) e controle bucindolol (CTR+BCD). A HAP foi induzida por meio de uma dose única de monocrotalina (60 mg/Kg – i.p.). Após duas semanas, os animas foram tratados por sete dias com bucindolol (2 mg/Kg/dia – i.p.) ou veículo. No 22º dia após a administração da monocrotalina, os animais foram anestesiados (i.p.) com quetamina (90 mg/Kg) e xilazina (10 mg/Kg), submetidos à ecocardiografia, cateterismo da artéria femoral, cateterismo do VD e decapitados, com posterior coleta dos tecidos. Os resultados foram avaliados utilizando ANOVA de duas vias (Sigma Plot 12.0) seguida pelo 8 teste de Student-Newman-Keuls, com nível de significância P<0,05. Os resultados serão apresentados na versão completa desta dissertação. / Pulmonary arterial hypertension is a rapidly progressive disease with poor prognosis, characterized by increase in pulmonary vascular resistance. As a result, there is an elevation of afterload imposed to the right ventricle and hypertrophy. Thus, since there is a rise in myocardial oxygen consumption, it is probable that oxidative stress is contributing to the development and progression of this disease. It is known that beta-adrenergic blockade reduces mortality in patients with left ventricular heart failure, but limited studies relate their use in right ventricular heart failure. The bucindolol is a beta-blocker that acts on receptors β1, β2, α1 and presents sympatholytic property. The aim of this study was to test the hypothesis that treatment with bucindolol could reduce right ventricular hypertrophy and improve systolic and diastolic function of the myocardium. Male Wistar rats weighing 130±10 grams were divided into four groups (n=7-10/group): monocrotaline without bucindolol (MCT WITHOUT BCD), monocrotaline bucindolol (MCT+BCD), control without bucindolol (CTR WITHOUT BCD) and control bucindolol (CTR+BCD). Pulmonary arterial hypertension was induced by a single dose of monocrotaline (60 mg/Kg – i.p.). After two weeks, the animals were treated for seven days with bucindolol (2 mg/Kg/day – i.p.) or vehicle. Twenty-two days after administration of monocrotaline, the animals were anesthetized intraperitoneally with ketamine (90 mg/Kg) and xylazine (10 mg/Kg), underwent echocardiography, catheterization of the femoral artery and of the right ventricle, decapitation and subsequent collection of tissues (heart, lungs, liver and tibia). The results were analyzed using two-way ANOVA (Sigma Plot 12.0) followed by 10 Student-Newman-Keuls test, with P<0.05 of significance level. Results will be presented in the full version.

A hipertensão arterial pulmonar (HAP) é caracterizada pelo aumento da resistência vascular pulmonar (RVP). Em decorrência, há elevação da pós-carga imposta ao ventrículo direito (VD) e hipertrofia. Assim, com aumento de consumo de O2 pelo miocárdio, é provável que o estresse oxidativo esteja participando do desenvolvimento e progressão desta doença. Sabe-se que o bloqueio beta-adrenérgico diminui a mortalidade de pacientes com insuficiência cardíaca à esquerda, porém pouquíssimas pesquisas referem sua utilização na insuficiência cardíaca à direita. O bucindolol é um beta-bloqueador que atua nos receptores β1, β2, α1 e com propriedade simpatolítica. O objetivo deste estudo foi testar a hipótese de que o tratamento com bucindolol poderia reduzir a hipertrofia do VD e melhorar a função sistólica e diastólica do miocárdio. Foram utilizados ratos Wistar machos pesando 130±10 gramas divididos em quatro grupos (n=7-10/grupo): monocrotalina sem bucindolol (MCT SEM BCD), monocrotalina bucindolol (MCT+BCD), controle sem bucindolol (CTR SEM BCD) e controle bucindolol (CTR+BCD). A HAP foi induzida por meio de uma dose única de monocrotalina (60 mg/Kg – i.p.). Após duas semanas, os animas foram tratados por sete dias com bucindolol (2 mg/Kg/dia – i.p.) ou veículo. No 22º dia após a administração da monocrotalina, os animais foram anestesiados (i.p.) com quetamina (90 mg/Kg) e xilazina (10 mg/Kg), submetidos à ecocardiografia, cateterismo da artéria femoral, cateterismo do VD e decapitados, com posterior coleta dos tecidos. Os resultados foram avaliados utilizando ANOVA de duas vias (Sigma Plot 12.0) seguida pelo 8 teste de Student-Newman-Keuls, com nível de significância P<0,05. Os resultados serão apresentados na versão completa desta dissertação. / Pulmonary arterial hypertension is a rapidly progressive disease with poor prognosis, characterized by increase in pulmonary vascular resistance. As a result, there is an elevation of afterload imposed to the right ventricle and hypertrophy. Thus, since there is a rise in myocardial oxygen consumption, it is probable that oxidative stress is contributing to the development and progression of this disease. It is known that beta-adrenergic blockade reduces mortality in patients with left ventricular heart failure, but limited studies relate their use in right ventricular heart failure. The bucindolol is a beta-blocker that acts on receptors β1, β2, α1 and presents sympatholytic property. The aim of this study was to test the hypothesis that treatment with bucindolol could reduce right ventricular hypertrophy and improve systolic and diastolic function of the myocardium. Male Wistar rats weighing 130±10 grams were divided into four groups (n=7-10/group): monocrotaline without bucindolol (MCT WITHOUT BCD), monocrotaline bucindolol (MCT+BCD), control without bucindolol (CTR WITHOUT BCD) and control bucindolol (CTR+BCD). Pulmonary arterial hypertension was induced by a single dose of monocrotaline (60 mg/Kg – i.p.). After two weeks, the animals were treated for seven days with bucindolol (2 mg/Kg/day – i.p.) or vehicle. Twenty-two days after administration of monocrotaline, the animals were anesthetized intraperitoneally with ketamine (90 mg/Kg) and xylazine (10 mg/Kg), underwent echocardiography, catheterization of the femoral artery and of the right ventricle, decapitation and subsequent collection of tissues (heart, lungs, liver and tibia). The results were analyzed using two-way ANOVA (Sigma Plot 12.0) followed by 10 Student-Newman-Keuls test, with P<0.05 of significance level. Results will be presented in the full version.

A hipertensão arterial pulmonar (HAP) é caracterizada pelo aumento da resistência vascular pulmonar (RVP). Em decorrência, há elevação da pós-carga imposta ao ventrículo direito (VD) e hipertrofia. Assim, com aumento de consumo de O2 pelo miocárdio, é provável que o estresse oxidativo esteja participando do desenvolvimento e progressão desta doença. Sabe-se que o bloqueio beta-adrenérgico diminui a mortalidade de pacientes com insuficiência cardíaca à esquerda, porém pouquíssimas pesquisas referem sua utilização na insuficiência cardíaca à direita. O bucindolol é um beta-bloqueador que atua nos receptores β1, β2, α1 e com propriedade simpatolítica. O objetivo deste estudo foi testar a hipótese de que o tratamento com bucindolol poderia reduzir a hipertrofia do VD e melhorar a função sistólica e diastólica do miocárdio. Foram utilizados ratos Wistar machos pesando 130±10 gramas divididos em quatro grupos (n=7-10/grupo): monocrotalina sem bucindolol (MCT SEM BCD), monocrotalina bucindolol (MCT+BCD), controle sem bucindolol (CTR SEM BCD) e controle bucindolol (CTR+BCD). A HAP foi induzida por meio de uma dose única de monocrotalina (60 mg/Kg – i.p.). Após duas semanas, os animas foram tratados por sete dias com bucindolol (2 mg/Kg/dia – i.p.) ou veículo. No 22º dia após a administração da monocrotalina, os animais foram anestesiados (i.p.) com quetamina (90 mg/Kg) e xilazina (10 mg/Kg), submetidos à ecocardiografia, cateterismo da artéria femoral, cateterismo do VD e decapitados, com posterior coleta dos tecidos. Os resultados foram avaliados utilizando ANOVA de duas vias (Sigma Plot 12.0) seguida pelo 8 teste de Student-Newman-Keuls, com nível de significância P<0,05. Os resultados serão apresentados na versão completa desta dissertação. / Pulmonary arterial hypertension is a rapidly progressive disease with poor prognosis, characterized by increase in pulmonary vascular resistance. As a result, there is an elevation of afterload imposed to the right ventricle and hypertrophy. Thus, since there is a rise in myocardial oxygen consumption, it is probable that oxidative stress is contributing to the development and progression of this disease. It is known that beta-adrenergic blockade reduces mortality in patients with left ventricular heart failure, but limited studies relate their use in right ventricular heart failure. The bucindolol is a beta-blocker that acts on receptors β1, β2, α1 and presents sympatholytic property. The aim of this study was to test the hypothesis that treatment with bucindolol could reduce right ventricular hypertrophy and improve systolic and diastolic function of the myocardium. Male Wistar rats weighing 130±10 grams were divided into four groups (n=7-10/group): monocrotaline without bucindolol (MCT WITHOUT BCD), monocrotaline bucindolol (MCT+BCD), control without bucindolol (CTR WITHOUT BCD) and control bucindolol (CTR+BCD). Pulmonary arterial hypertension was induced by a single dose of monocrotaline (60 mg/Kg – i.p.). After two weeks, the animals were treated for seven days with bucindolol (2 mg/Kg/day – i.p.) or vehicle. Twenty-two days after administration of monocrotaline, the animals were anesthetized intraperitoneally with ketamine (90 mg/Kg) and xylazine (10 mg/Kg), underwent echocardiography, catheterization of the femoral artery and of the right ventricle, decapitation and subsequent collection of tissues (heart, lungs, liver and tibia). The results were analyzed using two-way ANOVA (Sigma Plot 12.0) followed by 10 Student-Newman-Keuls test, with P<0.05 of significance level. Results will be presented in the full version.

Background: Pulmonary artery sarcoma is a rare tumor with a poor prognosis. Case Report: We report the case of a 64-year-old man with an intimal pulmonary artery sarcoma presenting with severe high oxygen flow-demanding dyspnea and weight loss of 12 kg in the last 6 months. On echocardiography, right heart insufficiency, markedly elevated right ventricular pressure, a pressure gradient along the right outflow tract, and a tumor mass adherent to the wall of the truncus pulmonalis were detected. The tentative diagnosis by echocardiographic findings was pulmonary artery sarcoma. Computed tomography of the thorax and 18-fluorodeoxyglucose positron emission tomography showed an advanced local tumor manifestation. Surgical resection of the tumor to improve hemodynamics confirmed the diagnosis. Conclusions: Pulmonary artery sarcoma should be considered as a rare differential diagnosis in patients with dyspnea due to right heart failure, particular in the case of additional weight loss, and echocardiographic examination is a useful first diagnostic approach in establishing the diagnosis. / Hintergrund: Das Pulmonalarteriensarkom ist eine seltene Erkrankung mit einer schlechten Prognose. Fallbericht: Wir berichten über einen 64-jährigen Mann mit einem intimalen Pulmonalarteriensarkom, der sich mit starker Luftnot trotz hoher Sauerstoffsubstitution und einem Gewichtsverlust von 12 kg in den letzten 6 Monaten vorstellte. Echokardiographisch fielen eine Rechtsherzinsuffizienz, ein deutlich erhöhter rechtsventrikulärer Druck, ein Druckgradient über dem rechten Ausflusstrakt und eine Tumormasse im Bereich des Trunkus pulmonalis mit Kontakt zur Gefäßwand auf. Die mittels Echokardiographie erhobene Verdachtsdiagnose lautete Pulmonalarteriensarkom. Die Computertomographie des Thorax und die 18-Flur-Desoxyglukose-Positron-Emissionstomographie erbrachten den Befund eines lokal fortgeschrittenen Tumors. Die chirurgische Resektion des Tumors, die zur Verbesserung der Hämodynamik durchgeführt wurde, bestätigte die Diagnose. Schlussfolgerungen: Das Pulmonalarteriensarkom sollte differenzialdiagnostisch als eine seltene Ursache der Luftnot im Rahmen einer Rechtsherzinsuffizienz, insbesondere bei zusätzlichem Gewichtsverlust, in Erwägung gezogen werden. Die Echokardiographie stellt eine wertvolle initiale Untersuchungsmethode bei der Diagnosestellung dar. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Pulmonell hypertension (PH) är en sjukdom med flera olika etiologier som bidrar till ett förhöjt tryck i lungkretsloppet. PH definieras som ett medelartärtryck i lungpulsådern   25mm Hg i vila uppmätt vid högersidig hjärtkateterisering (RHC). De olika orsakerna till PH delas in i fem grupper. Denna studie fokuserar på grupp I, som utgörs av pulmonell arteriell hypertension (PAH). PAH bidrar till en tryckbelastning av högerkammaren där högerkammaren måste arbeta mot ett högre tryck. Detta leder till en nedsatt högerkammarfunktion. I nuläget används right ventricular stroke work index (RVSWI) inom RHC, för att mäta högerkammarens arbete. Syftet med studien var att jämföra RVSWI beräknat med ekokardiografi och RHC. Detta för att finna ytterligare ett mått vid bedömning av högerkammarfunktion med ekokardiografi hos patienter med PAH. RVSWI beräknades med två ekokardiografiska metoder (RVSWIEKO1= 90 - (0,62 x pulmonalisflödets accelerationstid (PAT) x slagvolymindex (SVIEKO)), RVSWIEKO2= ((0,61 x maximala gradienten över tricuspidalisinsufficiensen (TRmaxPG)) + medeltrycket i höger förmak (mRAP) + 2) x SVIEKO). Båda metoderna påvisade statistisk signifikant skillnad (p &lt;0,001) i absoluta värden mot RVSWI erhållet med RHC.  En av metoderna (RVSWI EKO2) påvisade en måttlig korrelation mot RHC, medan RVSWI EKO1 hade en försumbar korrelation mot RHC. Studien visade att ekokardiografiskt beräknat RVSWI kan användas, som ett ytterligare mått vid bedömning av högerkammarens funktion. Det krävs dock fler studier för att parametern ska kunna användas kliniskt. / Pulmonary hypertension (PH) is a disease with many different etiologies contributing to an increased pressure in the pulmonary circulation. PH is defined as a mean arterial pressure in the pulmonary artery ≥ 25mm Hg at rest measured by right heart catheterization (RHC). The different causes of PH are divided into five groups. This study focuses on group I, which consists of pulmonary arterial hypertension (PAH). PAH contributes to a pressure overload of the right ventricle. The right ventricle must work at a higher pressure, which leads to a reduced right ventricular function. Currently, right ventricular stroke work index (RVSWI) by right heart catheterization (RHC) is a measure of right ventricular workload. The purpose of the study was to compare RVSWI calculated with echocardiography to RVSWI by RHC. And to find an additional measure for assessing right ventricular function by echocardiography in patients with PAH.  RVSWI was evaluated with two echocardiographic methods (RVSWIEKO1= 90 - (0,62 x pulmonary acceleration time (PAT) x stroke volume index (SVIEKO)), RVSWIEKO2= ((0,61 x tricuspid regurgitant maximum pressure gradient (TRmaxPG)) + mean right atrial pressure (mRAP) + 2) x SVIEKO). Both the echocardiographic methods showed a statistically significant difference (p &lt;0.001) in absolute values ​​compared to RVSWI by RHC. One of the echocardiographic methods (RVSWI EKO2) showed a moderate correlation with RHC, while RVSWIEKO1 showed a negligible with RHC. The study has shown that RVSWI evaluated with echocardiography can be used as an additional measure, when assessing right ventricular function. However, more studies are needed until the parameter can be used clinically.

La survenue d’une défaillance ventriculaire droite est associée à une augmentation de mortalité dans de nombreuses situations cliniques, particulièrement chez les patients atteints d’hypertension pulmonaire chronique. Les mécanismes conduisant à la dysfonction et la défaillance du ventricule droit lorsqu’il est soumis à une surcharge chronique de pression sont complexes et demeurent mal connus. Si une bonne adéquation entre les apports et les besoins accrus en oxygène est essentielle pour le maintien d’une fonction ventriculaire droite adaptée, il semblerait que l’altération de la microvascularisation myocardique pourrait être responsable de la présence d’ischémie myocardique et pourrait contribuer à la transition de la phase adaptée à la phase non adaptée de l’hypertrophie ventriculaire droite. La mitochondrie étant l’organelle oxygéno-dépendante responsable de la production d’énergie, l’intégrité de ses capacités oxydatives est également essentielle au bon fonctionnement du ventricule droit. Il semblerait que le métabolisme mitochondrial soit altéré dans le ventricule droit défaillant mais il existe peu de données au stade précoce dysfonction ventriculaire droite. Afin de mieux comprendre l’importance de ces mécanismes, nous avons modélisé l’hypertension artérielle pulmonaire chez le porc.La première partie de ce travail a consisté à mettre en évidence l’association entre l’altération de la microvascularisation et l’adaptation ventriculaire droite à une surcharge de pression. Pour cela, nous avons modélisé l’hypertension pulmonaire chez deux modèles porcins différents. L’un était un modèle de shunt entre la crosse aortique et le tronc de l’artère pulmonaire (SHUNT), l’autre était un modèle d’hypertension artérielle pulmonaire post-embolique (CTEPH). Un remodelage structurel et fonctionnel du ventricule droit était observé dans les 2 modèles. Dans cette étude, nous avons mis en évidence que la dysfonction ventriculaire droite précoce était associée à (1) un mismatch entre la microvascularisation et l’hypertrophie ventriculaire droite, traduit par une baisse de la densité capillaire, (2) à une baisse du ratio entre la densité capillaire et la charge de travail du ventricule droit (Strokework) et (3) à une augmentation de la fibrose myocardique.Dans la deuxième partie de cette thèse, nous avons étudié et comparé la densité capillaire et la fibrose myocardique ventriculaire droite chez 14 patients atteints de syndrome d’Eisenmenger et 14 patients atteints d’hypertension artérielle pulmonaire chronique. Ces 28 patients présentaient une défaillance ventriculaire droite symptomatique et avaient été traité par une transplantation cœur-poumon. La densité capillaire ventriculaire droite était identique dans les deux groupes et était environ 1,5 fois plus basse que dans un ventricule droit normal, confirmant l’atteinte microvasculaire chez ces patients.La troisième partie de ce travail a consisté à étudier les capacités respiratoires mitochondriales au cours du remodelage ventriculaire droit lorsqu’il est soumis à une surcharge chronique de pression. Il a ainsi été montré que, dans notre modèle porcin d’hypertension artérielle pulmonaire postembolique, les capacités respiratoires mitochondriales mesurées selon la méthode des fibres myocardiques perméabilisées étaient globalement diminuées, précocement dans l’évolution et sans diminution de la masse mitochondriale en microscopie électronique. Nous n’avons pas mis en évidence de modification de d’utilisation préférentiel de substrat par la mitochondrie au cours du temps dans cette étude.De manière générale, ces résultats démontrent le rôle de l’atteinte microvasculaire et de la dysfonction mitochondriale dans la dysfonction ventriculaire droite. Les voies moléculaires communes à ces deux mécanismes (PGC-1, HiF-1 entre autres) font l’objet d’étude afin d’identifier de nouvelles cibles thérapeutiques. / Right ventricular failure is associated with an increased mortality in several clinical features, especially in patients with pulmonary hypertension. Underlying mechanisms of right ventricular dysfunction and failure in chronic pressure overload are complex and still subject to debate. The balance between the supply and the increased need in oxygen is crucial to maintain an adapted right ventricular function. However, an impairment of the myocardial microvascularisation could lead to myocardial ischemia and could participate to the transition between adapted and non-adapted right ventricular hypertrophy. As mitochondrion are involved in the entire oxygen-dependent energy production in cardiomyocytes, their integrity is also essential for a good right ventricular function. It is suggested that mitochondrial metabolism is impaired in right ventricular failure. However, only few data exist at the early stage of right ventricular dysfunction. To better understand the importance of such mechanisms, we used a model of chronic pulmonary hypertension in piglets.The first aim of this thesis was to study the association between microvascularisation impairment and right ventricular adaptation to chronic pressure overload. We compared two different piglet models of pulmonary hypertension. The first model was a systemic-to-pulmonary shunt (SHUNT) between the aortic arch and the pulmonary trunk. The second model reproduced thromboembolic pulmonary hypertension (CTEPH). In this work, we showed that early right ventricular dysfunction was associated with (1) a mismatch between microvascularisation and right ventricular hypertrophy as showed by a decreased capillary density, (2) an importance of the capillary density to right ventricular stroke work ratio and (3) an increased of myocardial fibrosis.In the second part of this thesis, we studied and compared the capillary density and myocardial fibrosis in right ventricles of 14 Eisenmenger Syndrome patients and 14 patients with chronic pulmonary arterial hypertension. All 28 patients had symptomatic right ventricular failure and underwent heart-lung transplantation in our institution. Capillary density was not different between the two groups and was almost 1.5-fold lower than in normal right ventricle, confirming the impairment of microvascularisation in these patients.In the third part of this work, we studied the mitochondrial respiratory capacities in the setting of right ventricular remodeling under chronic pressure overload. Thus, we showed that, in our swine CTEPH model, the mitochondrial respiratory capacities were globally and early impaired. The mitochondrial mass assessed in transmission electronic microscopy was not decreased. We didn’t observe any modification of substrate use over time.Taking together, these results showed that microvascular impairment and mitochondrial dysfunction had an important role in the early right ventricular dysfunction. Molecular pathways involved in both mechanisms are currently studied to find new targeted therapeutics.

La fibrillation auriculaire (FA) est l’arythmie cardiaque la plus répandue. Les maladies du cœur droit (MCD), caractérisées par une hypertrophie et une inflammation myocardique augmentent le risque de FA. La relation tri-factorielle unissant les MCD, l’inflammation et la FA demeure peu décrite. L’hypothèse était qu’une constriction du tronc pulmonaire entraînerait une MCD induisant une inflammation auriculaire et une augmentation du risque de FA. Une ligature du tronc pulmonaire (LTP) fut réalisée chirurgicalement sur des rats Wistar mâles pour mimer une augmentation chronique de la post-charge du ventricule droit. Des rats Sham ont eu une chirurgie sans ligature. Tous les rats ont eu une échocardiographie puis une étude électrophysiologique pour évaluer leur vulnérabilité à la FA avant d’être sacrifiés aux jours 0, 7, 14 et 21 post-chirurgie. Leurs tissus auriculaires ont servi pour la cartographie optique de leur oreillette droite (OD), l’histologie, mais aussi pour la RPCq et l’immunobuvardage de type Western afin de quantifier des marqueurs inflammatoires/fibrotiques/sénescents et des canaux ioniques. Une hypertrophie et dilatation du cœur droit des rats LTP furent observées. Dès le 7e jour, les rats LTP avaient une vitesse de conduction électrique réduite dans leur OD et étaient vulnérables à la FA. De la fibrose s’était accumulée dans l’OD, coïncidant avec une élévation de l’expression de gènes pro-inflammatoires (Nlrp3) et pro-fibrotiques (Tgfβ1) ainsi qu’une diminution de la protéine SERCA2a. Cette étude a démontré qu’une MCD provoque une augmentation de l’inflammation et de la fibrose auriculaire droite associée à une croissance du risque de FA. / Atrial fibrillation (AF) is the most common cardiac arrhythmia. Right heart diseases (RHD), which are characterized by hypertrophy and myocardial inflammation can also increase the risk of AF. The tri-factorial relationship that exists between RHD, inflammation and AF remains poorly described. We hypothesized that a permanent constriction of the pulmonary trunk would provoke a severe RHD associated with atrial inflammation and an enhanced AF vulnerability. A pulmonary artery trunk banding (PAB) was surgically performed on male Wistar rats to mimic a chronic increase in right ventricular afterload. Sham rats had surgery without ligation. All rats underwent echocardiography and electrophysiological studies to measure their AF vulnerability before being euthanized on days 0, 7, 14 and 21 post-surgery. Their atrial tissues were used for the optical mapping of their right atrium, histology, but also qPCR and Western immunoblotting in order to quantify inflammatory/fibrotic/senescent markers and ionic channels. PAB provoked the hypertrophy and dilation of the right heart. Starting at day 7, conduction velocity was significantly reduced in PAB rats compared to Sham. The right atrium (RA) dimension, RA fibrosis and AF vulnerability were significantly increased in PAB rats compared to Sham. The expression of pro-inflammatory (Nlrp3) and pro-fibrotic (Tgfβ1) genes was increased, and the levels of the SERCA2a protein were decreased in PAB rats compared to Sham. Our study demonstrated that a RHD in rats can induce an increase in RA inflammation and fibrosis, which are associated with an increased risk of AF.