Fundamentos O acesso percutâneo ao espaço pericárdico pela via transatrial poderia ser uma alternativa ao acesso subxifóide para o mapeamento e ablação de fibras miocárdicas subepicárdicas. O objetivo deste estudo foi avaliar a viabilidade de alcançar o espaço pericárdico normal através do apêndice auricular direito (AAD) por acesso transvenoso. Métodos e Resultados - Um sistema Mullins (8F), originalmente desenvolvido para alcançar o átrio esquerdo (AE) por punção transeptal foi utilizado neste estudo para transfixar o AAD (16) ou AE (1) em 17 suínos, com uma média de 26,9 ± 2,6 kg, e alcançar o espaço pericárdico normal. Um cateter 7F quadripolar com eletrodo distal com 4 ou 8 mm foi introduzido no espaço pericárdico para aplicações de radiofrequência. Em 15 (88%) animais o procedimento foi realizado sem instabilidade hemodinâmica (PA média inicial = 80,4 ± 11.7 mmHg; PA média final = 86,8 ± 9.7 mmHg, p = 0,11). Foi identificado e aspirado derrame pericárdico discreto (28,9 ± 27.6 ml/animal) durante o procedimento. O espaço pericárdico foi acidentalmente acessado por punção do ventrículo direito (VD) em um animal e por punção do anel da valva tricúspide em outro. Ambos apresentaram sangramento xii pericárdico importante e tamponamento cardíaco. Um dispositivo para oclusão do orifício de perfuração foi testado com sucesso em três porcos, dois no AD e um no VD, sem ocorrência de derrame pericárdico significativo. Conclusões O acesso transatrial ao espaço pericárdico pode ser potencialmente útil para mapeamento e ablação de arritmias cardíacas, bem como para drenagem imediata de um tamponamento cardíaco agudo / Background A transvenous access to the pericardial space could provide a convenient route to map and ablate subepicardial myocardial fibers. The aim of this study was to evaluate the feasibility of reaching the normal pericardial space through the right atrial appendage (RAA) by transvenous access. Methods and Results An 8F Mullins system was used to transfix the right atrium (16) and left atrium (1) in 17 pigs with a mean of 26.9 ± 2.6 kg. A 7F quadripolar catheter with 4 or 8 mm distal tip electrode was introduced into the pericardial space to perform epicardial radiofrequency lesions. The pericardial space was successfully reached in 15 (88%) animals without hemodynamic instability (initial mean BP 80.4 ± 11.7 mmHg; final 86.8 ± 9.7 mmHg, p= 0,11). However, a mild pericardial serohemorrhagic effusion was identified and aspirated in all the animals (28.9 ± 27.6 ml/pig) during the procedure. The pericardial space was accidentally accessed through the right ventricle (RV) in one animal and through the tricuspid annulus in another, which presented important pericardial bleeding and cardiac tamponade. The hypothesis that an occlusion device could be useful to close the created atrial xiv orifice was tested successfully in thee pigs (two at RAA and one at RV) and without significant pericardial bleeding. Conclusions The right atrial appendage route might be potentially useful to access the normal pericardial space for mapping and ablating cardiac arrhythmias as well as to drain promptly an acute tamponade

La fibrillation auriculaire postopératoire (FAPO) est une complication fréquente de la chirurgie cardiaque et est associée à une morbidité et des coûts accrus. Bien que de nombreuses méthodes prophylactiques aient été évaluées, aucune n’est actuellement universellement employée compte tenu du risque de complications, de contre-indications et du manque de données probantes. Ce mémoire tente d’examiner la contribution du sang intra-péricardique à la genèse de fibrillation auriculaire après une chirurgie cardiaque et d’évaluer son potentiel en tant que cible prophylactique. Trois études furent réalisées dans le cadre de ce travail. Dans un premier temps, une revue de la littérature fut pilotée afin d’éclaircir les éléments pathophysiologiques et cliniques unissant l’accumulation de sang dans le sac péricardique à la FAPO. Ensuite, un projet rétrospectif avec analyse par score de propension et un essai clinique randomisés furent menés afin d’évaluer l’effet d’un protocole de drainage thoracique adoptant un dispositif de dégagement actif des drains [active tube clearance (ATC)], visant à prévenir la formation de caillots intraluminaux, sur l’incidence de FAPO. La première étude conclut que la présence de sang intra-péricardique, via l’activation de processus inflammatoire et oxydatif local, est un facteur périopératoire contribuant à la survenue de FAPO. La seconde étude identifia l’utilisation de l’ATC en tant que facteur protecteur indépendant contre la FAPO. Finalement, la dernière étude démontra une diminution non-significative du risque relatif de FAPO de 18% associée à l’ATC. En somme, un drainage efficace du péricarde pourrait réduire l’incidence de FAPO, or les modalités optimales demeurent à être spécifiées. / Postoperative atrial fibrillation (POAF) is a common complication of cardiac surgery that is associated with increased morbidity and costs. Although numerous prophylactic measures have been evaluated, none have been universally implemented considering the risk of complications, contraindications and lack of evidence. The aim of this thesis is to examine the role of intrapericardial blood in the development of POAF after cardiac surgery and evaluate its potential as a target for prophylaxis. For this thesis, a total of three studies were carried out. To begin, a literature review was conducted to elucidate the pathophysiological and clinical elements connecting the accumulation of shed blood within the pericardial sac to POAF. Afterwards, both a retrospective study with propensity score analysis and a randomized controlled trial were carried out to evaluate the incidence of POAF after implementing a universal postoperative chest drainage protocol using an active tube clearance (ATC) device, designed to prevent intraluminal clogging and improve drainage. The first study concluded that the presence of intra-pericardial blood, through the activation of local and oxidative processes, is a perioperative factor triggering POAF in susceptible individuals. The second study identified the use of ATC as an independent protective factor against POAF. Finally, the last study demonstrated a 15% non-significant relative risk reduction of POAF associated with ATC. In conclusion, an efficient pericardial drainage could reduce the incidence of POAF after cardiac surgery. However, the optimal strategy has yet to be determined.

Leaflet replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. Hemodynamic performance and mechanical stress levels were investigated after porcine AVr with 5 types of clinically relevant replacement materials to ascertain which material(s) would be best suited for repair. Porcine aortic roots with intact aortic valves were placed in a left-heart simulator mounted with a high-speed camera for baseline valve assessment. Then, the non-coronary leaflet was excised and replaced with autologous porcine pericardium (APP), glutaraldehyde-fixed bovine pericardial patch (BPP; Synovis™), extracellular matrix scaffold (CorMatrix™), or collagen-impregnated Dacron (HEMASHIELD™). Hemodynamic parameters were measured over a range of cardiac outputs (2.5–6.5L/min) post-repair. Material properties of the above materials along with St. Jude Medical™ Pericardial Patch with EnCapTM Technology (SJM) were determined using pressurization experiments. Finite element models of the aortic valve and root complex were then constructed to verify the hemodynamic characteristics and determine leaflet stress levels. This study demonstrates that APP and SJM have the closest profiles to normal aortic valves; therefore, use of either replacement material may be best suited. Increased stresses found in BPP, HEMASHIELD™, and CorMatrix™ groups may be associated with late repair failure.

Leaflet replacement in aortic valve repair (AVr) is associated with increased long-term repair failure. Hemodynamic performance and mechanical stress levels were investigated after porcine AVr with 5 types of clinically relevant replacement materials to ascertain which material(s) would be best suited for repair. Porcine aortic roots with intact aortic valves were placed in a left-heart simulator mounted with a high-speed camera for baseline valve assessment. Then, the non-coronary leaflet was excised and replaced with autologous porcine pericardium (APP), glutaraldehyde-fixed bovine pericardial patch (BPP; Synovis™), extracellular matrix scaffold (CorMatrix™), or collagen-impregnated Dacron (HEMASHIELD™). Hemodynamic parameters were measured over a range of cardiac outputs (2.5–6.5L/min) post-repair. Material properties of the above materials along with St. Jude Medical™ Pericardial Patch with EnCapTM Technology (SJM) were determined using pressurization experiments. Finite element models of the aortic valve and root complex were then constructed to verify the hemodynamic characteristics and determine leaflet stress levels. This study demonstrates that APP and SJM have the closest profiles to normal aortic valves; therefore, use of either replacement material may be best suited. Increased stresses found in BPP, HEMASHIELD™, and CorMatrix™ groups may be associated with late repair failure.