Abstract Purpose: To investigate the effects of atenolol in inflammatory mediator and oxidative stress in a myocardial injury by intestinal ischemia/reperfusion in rat model. Methods: Adult Wistar male rats were randomly (n=8), anesthetized and divided in: Sham: submitted to operation only; group SS+IR: intravenous saline infusion following superior mesenteric artery occlusion during 60 minutes (ischemia) and open for 120 minutes (reperfusion); group AT+IR: intravenous atenolol infusion (2 mg/kg) following superior mesenteric artery occlusion during 60 minutes (ischemia) and open for 120 minutes (reperfusion); and group AT+I+AT+R: intravenous atenolol infusion following superior mesenteric artery occlusion during 60 minutes (ischemia) and in the time 45 minutes other atenolol doses were administrated and the artery was open for 120 minutes (reperfusion), all animals were submitted to muscular relaxation for mechanical ventilation. In the end of experiment the animals were euthanized and the hearts tissue were morphology analyzed by histology and malondialdehyde by ELISA, and the plasma were analyzed for tumor necrosis factor-alpha by ELISA. Results: The group SS+IR demonstrated the higher malondialdehyde levels when compared with the atenolol treated-groups (p=0.001) in the heart tissue. The tumor necrosis factor-alpha level in plasma decrease in the treated groups when compared with SS+IR group (p=0.001). Histology analyses demonstrate pyknosis, edema, cellular vacuolization, presence of inflammatory infiltrate and band contraction in the heart tissue of the rats. Conclusion: Atenolol significantly reduce the degree of cardiac damage after intestinal ischemia-reperfusion.

FUNDAMENTO: O sistema de mapeamento eletro anatômico Ensite Navx é muito usado na ablação por radiofrequência (RF) da fibrilação atrial, ajudando na confecção de lesões lineares. Contudo, a correspondência da linha virtual criada pelo Ensite com a lesão patológica ainda não foi avaliada. OBJETIVO: Avaliar a continuidade da linha virtual criada pelo Ensite em modelo suíno. MÉTODOS: Realizamos ablação linear por RF (cateter de 8 mm e irrigado) em ambos os átrios de 14 suínos (35 kg) guiada pelo EnSite. Os animais foram sacrificados 14 dias pós-ablação para análise macroscópica e histológica. RESULTADOS: Foram confeccionadas 23 lesões lineares em átrio direito e 21 em átrio esquerdo dos 14 animais. A potência, temperatura e impedância médias das aplicações foram de 56 W, 54 ºC e 231 Ω para o cateter de 8mm, e de 39 W, 37 ºC e 194 Ω para o cateter irrigado. Todas (100%) as linhas foram identificadas nas faces epicárdica e endocárdica, denotando transmuralidade. À macroscopia, as lesões eram extensas e pálidas, com 3,61 cm de comprimento e 0,71 cm de profundidade e contínuas. A transmuralidade das lesões foi confirmada pela microscopia. Houve correspondência na localização das linhas do mapa virtual com as da peça anatômica em 21 das 23 (91,3%) das linhas do átrio direito e 19/21 (90,4%) do átrio esquerdo. CONCLUSÃO: Nesse modelo, as linhas criadas no mapa virtual pelo sistema EnSiteNavX se correlacionam a lesões lineares transmurais contínuas na peça anatômica, sugerindo que esse método é adequado para a ablação linear da fibrilação atrial.

BACKGROUND: EnSiteNavx electroanatomic mapping system is widely used in radiofrequency (RF) atrial fibrillation ablation, helping the creation of linear lesions. However, the correspondence of the virtual line created by EnSite with the pathological lesion has not yet been evaluated. OBJECTIVE: to assess the continuousness of Ensite-guided virtual lines in a swine model. METHODS: we performed RF ablation linear lesions (8mm and irrigated catheters tips) in both atria of 14 pigs (35Kg) guided by the EnSite. The animals were sacrificed 14 days post-ablation for macroscopic and histological analysis. RESULTS: a total of 23 lines in the right atrium and 21 lines in the left atrium were created in 14 animals. The medium power, impedance and temperature applications were 56 W, 54 ºC and 231 Ω for the 8mm tip, and 39W, 37ºC, 194 Ω for the irrigated tip catheter, respectively. All (100%) lines were identified on the epicardial and endocardial surfaces, denoting transmurality. At macroscopic examination, lesions were extensive and pale, continuous, with 3.61 cm long and 0.71 cm deep. The transmurality of the lesions was confirmed by microscopy. There was a correlation in the location of the lines at the virtual map and the anatomical lesions in 21 of 23 (91.3%) of the right atrium and 19/21 (90.4%) of the left atrium. CONCLUSION: In this model, the lines created in the virtual map by EnSiteNavX system correspond to continuous transmural linear lesions in anatomical specimen, suggesting that this method is suitable for linear ablation of atrial fibrillation.

FUNDAMENTO: Os corticosteroides limitam o crescimento tardio das lesões por radiofrequência (RF) no músculo da coxa de ratos filhotes, mas seus efeitos em ratos púberes e adultos são desconhecidos. OBJETIVO: Avaliar os efeitos dos corticoesteroides na cicatrização das lesões por RF no músculo da coxa de ratos em diferentes faixas etárias. MÉTODOS: Realizou-se ablação no músculo da coxa de 30 ratos (1 lesão por animal): infantis (30 dias de idade, peso 73 g, n = 10), púberes (60 dias de idade, peso 230 g, n = 10) e 10 adultos (90 dias de idade, 310 g, n = 10), subdivididos em controles e tratados, que receberam Hidrocortisona (10 mg/kg IM pós-RF) e Betametasona (3,5 mg/kg IM, duas vezes por semana, por 29 dias). Os ratos foram sacrificados 60 dias após a ablação para análise histopatológica e planimétrica com software específico (ImageJ®). RESULTADOS: Nos infantis, púberes e adultos o ganho de peso no seguimento não diferiu entre controles e tratados. Nos controles, as lesões dos infantis e púberes eram maiores (p = 0,01) que as dos adultos. O tratamento reduziu o tamanho da lesão nos infantis (5,58+0,61 mm² vs 4,02+0,23 mm²; p < 0,01) e nos púberes (5,20+0,47 mm² vs 4,16+0,48 mm²; p < 0,01), mas não nos adultos (4,44+0,50 mm² vs 4,79+0,53 mm², p = NS). Tratados Infantil e Púbere apresentaram menor deposição de colágeno e menos traves fibróticas invadindo o tecido saudável a partir da área de fibrose central, e compondo lesão de dimensões notadamente mais reduzidas que seus controles. Não houve diferenças nos grupos adultos. CONCLUSÃO: Os corticoesteroides parecem reduzir o crescimento tardio da lesão, além de atenuar a proliferação fibrótica nos ratos infantis e púberes.

BACKGROUND: The corticosteroids limit the late growth of the lesions by radiofrequency (RF) on the rats' infants' thighs, but the effects on the pubescent and adult rats are unknown. OBJECTIVE: Evaluate the effects of the corticosteroids in the healing of the lesions by RF on the rats' thighs muscles in different age groups. METHODS: Ablation was performed on the thigh muscle of 30 rats (1 lesion per animal): infants (30 days old, weight 73 g, n = 10), pubescents (60 days old, weight 230 g, n = 10) and 10 adults (90 days old, 310 g, n = 10), subdivided in control and treated groups, that received Hydrocortisone (10 mg/kg IM post-RF) and Betametasone (3.5 mg/kg IM, twice a week, for 29 days). The rats were sacrificed 60 days after the ablation for hystopathological and planimetric analysis with specified software (ImageJ®). RESULTS: In the infant, pubescent and adult groups, the weight gain in the follow up did not differ between the control and the treated ones. In the control group, the lesions of the infants and pubescents were superior (p = 0.01) to the adults'. The treatment reduced the size of the lesion in the infants (5.58+0.61 mm² vs 4.02+0.23 mm²; p < 0.01) and pubescents (5.20+0.47 mm² vs 4.16+0.48 mm²; p < 0.01), but not in the adults (4.44+0.50 mm² vs 4.79+0.53 mm², p = NS). Infant and pubescent treated groups presented lower collagen deposition and less fibrotic bands invading the healthy tissue from the central fibrosis area, and forming lesions with remarkably more reduced dimensions than their controls. There were no differences in the adult groups. CONCLUSION: The corticosteroids seem to reduce the late growth of lesion, in addition to attenuate the fibrotic proliferation in the infant and pubescent rats.