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Développement d’un modèle expérimental porcin d’autorétroperfusion myocardique à coeur battant : évaluation des réponses hémodynamiques et cardiaques avant et après occlusion de l’artère interventriculaire antérieure : potentialités d’applications cliniques

Abstract : Part I: Objectives. This work reports an anatomic study of swine heart in order to produce technical recommendations and achieve successful experimental cardiac surgical procedures. Methods. 16 swines were studied. Coronary artery vessels were surgically (n=13) and angiographically (n=10) assessed. Coronary venous vessels were studied by anatomic dissections (n=13) and retrograde injection of methylene blue through the coronary sinus (n=8). Results. Specific pericardial positioning of swine heart dramatically differs from human heart resulting in a limited access to ascending aorta and right atrium, requiring surgical precautions to perform a safe sternotomy and canulation of ascending aorta with an antegrade cardioplegia. Arterial coronary pattern is similar to that of humans (right dominant supply: 70%). Pig coronary sinus receives 4 main branches vs 3 in human sinus. Preliminary ligation of the left azygos vein is required to visualize the surface distribution of methylene blue within the venous vessels, thereby confirming an optimized perfusion of the left ventricle whereas the right ventricle remains poorly perfused. This asymmetry of perfusion results from a specific venous drainage of the right ventricle through small cardiac veins disconnected from coronary sinus. Conclusions. Anatomic knowledge of swine heart validated surgical guidelines for designing the model of self-myocardial retroperfusion and safely performing experimental cardiac surgical procedures. Part II: Background. Retrograde perfusion into the coronary sinus is used to deliver cardioplegia. We developed an in-vivo porcine beating-heart model of self-myocardial retroperfusion (SMR) using the venous route to supply myocardial oxygenation and sought to assess hemodynamic and cardiac responses triggered by SMR before and after a prolonged occlusion of the LAD.Methods. A bypass-line between the ascending aorta and the coronary sinus was made to perform a selective retrograde perfusion of the great cardiac vein with oxygenated blood (SMR). A Control group (n=6) was assigned to collect baseline data, and an SMR group (n=6) was dedicated to undergo SMR with occlusion of LAD for 240 minutes. Cardiac output (CO), maximal pressure in the LV (Pmax in-LV), stroke volume (SV), left ventricular ejection fraction (LVEF), diastolic durations, heart rate, and arterial systemic pressure were evaluated with conductance catheters for the following periods: basal (before SMR), SMR with patent LAD, and SMR with occluded LAD. In order to assess peripheral perfusion, patterns of sublingual microcirculation were analyzed. At the end of the procedures, the hearts were harvested for histology. Results. Echographic LVEF evaluation was affected by sternotomy, but conductance catheter evaluation was not. Following pericardiotomy, CO decreased by 7.51% (P < 0.05). SMR with patent LAD showed inotropic properties with improvements in CO, SV, Pmax in-LV and LVEF (P < 0.0001). Following LAD occlusion, SMR supplied myocardial oxygenation with hemodynamic compensation and preserved the peripheral perfusion. Histology confirmed no signs of infarct. Conclusions. SMR showed capacities to produce inotropic effects and protect against ischemia, opening interesting potential applications
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Daniel Grandmougin. Développement d’un modèle expérimental porcin d’autorétroperfusion myocardique à coeur battant : évaluation des réponses hémodynamiques et cardiaques avant et après occlusion de l’artère interventriculaire antérieure : potentialités d’applications cliniques. Cardiologie et système cardiovasculaire. Université de Lorraine, 2018. Français. ⟨NNT : 2018LORR0098⟩. ⟨tel-01885814⟩

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