As conexinas são proteínas essenciais e estão diretamente relacionadas à propagação do impulso elétrico no coração, à velocidade de condução bem como à gênese de muitas afecções cardíacas. Em face da circulação extracorpórea (CEC) ainda ser utilizada de forma inconsistente na medicina veterinária e devido aos poucos estudos observados na literatura sobre os efeitos provocados pelo emprego da CEC na expressão da conexina 43 (Cx43) no miocárdio, objetivou-se avaliá-la em 15 animais da espécie canina, distribuidos em três grupos (C, CEC-1 e CEC -2) sendo, respectivamente, antes de realizada a CEC, com 60 minutos após esta e 60 minutos de CEC seguida de 30 minutos de restauração da perfusão espontânea. Avaliou-se a Cx43 pelas técnicas de imunofluorescência, western blot e RT-PCR em tempo real no tecido muscular cardíaco de regiões correspondentes aos átrios direito (AD) e esquerdo (AE), ventrículos direito (VD) e esquerdo (VE) e septo transverso. Os resultados indicaram a presença da Cx43 em todas as regiões do miocárdio nos grupos C, CEC-1 e CEC-2. A expressão da Cx43 variou significativamente em CEC-2 no AE e VD em relação ao grupo C (p<0,05). A expressão gênica de Gja1 (gene da Cx43) não apresentou diferença significativa entre os grupos estudados. Em CEC-2 identificou-se a presença de vacuolização na túnica média de artérias de pequeno calibre do miocárdio. Concluiu-se também que a canulação da aorta bem como a instalação do circuito de CEC no modo aorto-bicaval constitui técnica exequível / Connexins are essential proteins that are directly associated with electrical impulse propagation and speed of propagation in the heart. They also play a major role in numerous heart conditions. The use of cardiopulmonary bypass (CPB) in veterinary medicine is inconsistent and few studies describe the effect of cardiopulmonary bypass on the expression of connexin 43 (Cx43) in the myocardium. The objective of this study was to evaluate myocardial expression of Cx43. Connexin 43 of 15 dogs was assessed at 3 moments: prior to CPB (Group C); 60 minutes after CPB (Group CPB1); and 60 minutes after CPB followed by 30 minutes of spontaneous perfusion (Group CPB2). Assessment of Cx43 included immunofluorescence, western blot and RT-PCR real time of heart tissue samples from the right atrium (RA), left atrium (LA), right ventricle (LV), right ventricle (RV) and transverse septum. Our results showed the presence of Cx43 in all 5 areas of the myocardium in groups C, CPB1 and CPB2. A significant variation on the expression of Cx43 was observed when CPB2 LA and CPB2 RV were compared to group C (p<0,05). Expression of Gja1 (gene for Cx43) did not vary significantly among the study groups. Group CBP2 presented vacuolation of the tunica media of small myocardial arteries. We conclude that cannulation of the aorta and aorto-bicaval setup of the CPB circuit is feasible technique

Introduction: Neurological complications and stroke in association with cardiac surgery is a serious problem. The stroke event can occur during surgery (early stroke) or in the postoperative period with a symptom free interval (delayed stroke). Particle embolization due to aortic manipulation during surgery has been suspected as a mechanism for early stroke. The present thesis address mechanisms and survival effects of stroke both clinically (I-III) and experimentally (IV-V). Methods: Study I) Within a cohort of 2641 consecutive cases, a group of cardiac surgery patients with stroke and evaluated by computed tomography (CT) were studied (n=77). CT-findings were analyzed in relation to stroke symptoms. Study II) Data from 9122 patients undergoing coronary surgery were analyzed. Records of patients with any signs of neurological complications were reviewed to extract 149 subjects with stroke at extubation (early, 1.6%) versus 99 patients having a free interval (delayed, 1.1%). Early and delayed stroke were evaluated separately. Independent risk factors for stroke were analyzed by logistic regression and survival by Cox regression (9.3 years median follow-up). Study III) Patients with early (n=223) and delayed stroke (n=116) were identified among 10809 patients undergoing cardiac and aortic surgery, both groups exposed to cardiopulmonary bypass. Stroke patients were subdivided by the hemispheric location of lesions. Subgroups were compared and their associated pre- and peroperative variables and survival were analyzed. Study IV) Aortic cross-clamp manipulation was studied in a human cadaveric perfusion model. The pressurized aorta was repeatedly cross-clamped and washout samples were collected before and after clamp maneuvers. Particles in the washout samples were evaluated by microscopy and by digital image analysis. Study V) Pig aortas were pressurized and cannulated. Washout samples were collected before and after cannulation (n = 40). Particles were deposited onto a 10-μm filter to be evaluated by microscopy and digital image analysis. Results: Study I) In the group of patients exposed to routine cardiac surgery (i.e., clamping and cannulation) and with early stroke, right-hemispheric lesions were more frequent than of the contra-lateral side (P=0.005). Patients with aortic dissections had a strong dominance of bilateral findings, which was different from the unilateral pattern in the routine-surgery group (P&lt;0.001). Study II) Early and delayed stroke did not share any risk factors. Both early and delayed stroke explained mortality in the early postoperative period (P&lt;0.001, P&lt;0.001 respectively) but also at long term follow-up (P=0.008, P&lt;0.001 respectively). For patients surviving their first postoperative year, delayed but not early stroke influenced long-term mortality (P=0.001 and P=0.695, respectively). Study III) Stroke lesions in association to cardiac surgery were near exclusively ischemic. Early stroke had a preponderance for right-hemispheric lesions (P=0.009). In contrast, patients with early stroke that had undergone surgery of the aorta with circulatory arrest showed a pattern with more bilateral lesions compared to ‘cardiac-type’ operations (P&lt;0.001). Patients with bilateral lesions had a dramatically impaired survival compared to those with unilateral lesions (P&lt;0.001). Study IV) In the cadaveric perfusion model, cross-clamping produced a significant output of particles, which was seen for size intervals of 1 mm and smaller (P=0.002 to P=0.022). In all size intervals the particle output correlated with the degree of overall aortic calcification (P =0.002 to P=0.025). Study V) At cannulation of the pig aorta, more particles were noted after cannulation compared to before the maneuver (P&lt;0.001). This increase included small (&lt;0.1 mm, P&lt;0.001) and intermediate-size particles (0.1-0.5 mm, P&lt; 0.001). Particles above 0.5 mm were few and were not associated with cannulation. Conclusions: The influence of stroke on mortality was devastating, for both early and delayed stroke. These two stroke groups had obvious differences in both their risk factors and their hemispheric distribution. It is here emphasized that early and delayed stroke should be considered as two separate entities with suggested mechanistic differences. Ischemic lesions accounted for near all stroke events seen in association to cardiac surgery. For early stroke, these were mostly located within the right hemisphere. Results from the experimental studies underscore microembolic risks associated with aortic manipulation.

As conexinas são proteínas essenciais e estão diretamente relacionadas à propagação do impulso elétrico no coração, à velocidade de condução bem como à gênese de muitas afecções cardíacas. Em face da circulação extracorpórea (CEC) ainda ser utilizada de forma inconsistente na medicina veterinária e devido aos poucos estudos observados na literatura sobre os efeitos provocados pelo emprego da CEC na expressão da conexina 43 (Cx43) no miocárdio, objetivou-se avaliá-la em 15 animais da espécie canina, distribuidos em três grupos (C, CEC-1 e CEC -2) sendo, respectivamente, antes de realizada a CEC, com 60 minutos após esta e 60 minutos de CEC seguida de 30 minutos de restauração da perfusão espontânea. Avaliou-se a Cx43 pelas técnicas de imunofluorescência, western blot e RT-PCR em tempo real no tecido muscular cardíaco de regiões correspondentes aos átrios direito (AD) e esquerdo (AE), ventrículos direito (VD) e esquerdo (VE) e septo transverso. Os resultados indicaram a presença da Cx43 em todas as regiões do miocárdio nos grupos C, CEC-1 e CEC-2. A expressão da Cx43 variou significativamente em CEC-2 no AE e VD em relação ao grupo C (p<0,05). A expressão gênica de Gja1 (gene da Cx43) não apresentou diferença significativa entre os grupos estudados. Em CEC-2 identificou-se a presença de vacuolização na túnica média de artérias de pequeno calibre do miocárdio. Concluiu-se também que a canulação da aorta bem como a instalação do circuito de CEC no modo aorto-bicaval constitui técnica exequível / Connexins are essential proteins that are directly associated with electrical impulse propagation and speed of propagation in the heart. They also play a major role in numerous heart conditions. The use of cardiopulmonary bypass (CPB) in veterinary medicine is inconsistent and few studies describe the effect of cardiopulmonary bypass on the expression of connexin 43 (Cx43) in the myocardium. The objective of this study was to evaluate myocardial expression of Cx43. Connexin 43 of 15 dogs was assessed at 3 moments: prior to CPB (Group C); 60 minutes after CPB (Group CPB1); and 60 minutes after CPB followed by 30 minutes of spontaneous perfusion (Group CPB2). Assessment of Cx43 included immunofluorescence, western blot and RT-PCR real time of heart tissue samples from the right atrium (RA), left atrium (LA), right ventricle (LV), right ventricle (RV) and transverse septum. Our results showed the presence of Cx43 in all 5 areas of the myocardium in groups C, CPB1 and CPB2. A significant variation on the expression of Cx43 was observed when CPB2 LA and CPB2 RV were compared to group C (p<0,05). Expression of Gja1 (gene for Cx43) did not vary significantly among the study groups. Group CBP2 presented vacuolation of the tunica media of small myocardial arteries. We conclude that cannulation of the aorta and aorto-bicaval setup of the CPB circuit is feasible technique

Background: Despite the successful development in cardiac surgery, cerebrovascular accidents (CVA) remain a devastating complication. Aortic atherosclerosis has been identified as a major risk factor for CVA. The present thesis addresses this question in relation to aortic manipulation during cardiac surgery, being divided into a clinical (I-II) and an experimental part (III-V). Material and methods: Consecutive cardiac surgery cases (n=2641) were analyzed. Patients with CVA were extracted from a database designed to monitor clinical symptoms. Patient records were used to confirm clinical data and diagnosis. Subdivision was made into three groups: control subjects, immediate, and delayed CVA, being analyzed for neurological symptoms (I). Patients with CVA who also had been investigated with computer tomography (CT) (n=77) were further evaluated in terms of hemispheric and vascular distribution of lesions. The CT-findings were compared with CVA symptoms (II). An aortic perfusion model was developed using cadaver aorta onto which multiple cross-clamp manipulations were applied (III). Washout samples of perfusate were analyzed by computerized image processing and with subdivision into different particle spectra. The model was further developed with the introduction of intraluminal manipulation from cannula and intra-aortic filter (IV). A technique for macro-anatomic mapping of plaque distribution of cadaver thoracic aorta was developed (V). Variation in plaque density was analyzed in different anatomical segments, monitored by digital image analysis. Hazards associated with surgical manipulation were studied by superimposing cannulation and cross-clamp sites onto the aortic maps in a blinded fashion. Results: The incidence of immediate and delayed CVA was 3.0% and 0.9%, respectively. Aortic quality was a strongly associated with immediate but not delayed CVA. Left-sided symptoms of immediate CVA were significantly more frequent than of the contra-lateral side. Positive signs on CT were seen in 66% of the CVA patients. Right-hemispheric lesions were more frequent compared with the contra-lateral side and the middle-cerebral artery territory dominated. Aortic cross-clamping produced a substantial output of particulate matter. Manipulation by intra-aortic filter produced a significant washout of embolic particles that escaped the filter, although some particles were captured. Cannulation was an additional source of embolic material. In terms of plaque distribution was the anterior wall of the ascending part and arch of the aorta more affected than its posterior side. However, observing a plaque in the anterior wall of this aortic segment predicted to 83% a concomitant plaque in the posterior wall. Increased age correlated positively with plaque density. The theoretical chance of interfering with a plaque during cannulation and/or clamp positioning was 45.8%. Conclusions: Both CT scans and clinical symptoms confirmed that CVA after cardiac surgery had a right-hemispheric predominance. The perfusion model resulted in a profound output of material during cross-clamp maneuvers. The intra-aortic filter successfully collected particles but also generated embolic debris on its own. Aortic cannulation was an additional source of embolic debris. Plaques were frequently found in the cadaveric aorta, and there was a high risk of plaque interference during surgical manipulation. As expected, plaque density was age-dependent.