Otoni Moreira Gomes

The ischemic preconditioning and postconditioning effect on the intestinal mucosa of rats undergoing mesenteric ischemia/reperfusion procedure

PURPOSE To evaluate the effect of the ischemic preconditioning and the ischemic postconditioning over the tissue injury in the intestinal mucosa of rats undergoing the procedure of mesenteric ischemia and reperfusion. METHODS Thirty Wistar rats were studied, divided in three groups: group A, undergoing mesenteric ischemia (30 minutes) and reperfusion (60 minutes); group B, mesenteric ischemia and reperfusion preceded by ischemic preconditioning; group C, mesenteric ischemia and reperfusion and, before the beginning of reperfusion, the ischemic postconditioning was performed. At the end, a segment of the small intestine was dissected for histological analysis. The results were evaluated using the CHIU et al.6 classification followed by the statistic treatment. RESULTS The mean values of the tissue injury levels were: group A, 3.5; group B, 1.2; and group C, 1. The difference between the result of group A with the results of groups B and C was considered statistically significant (p < 0,05). CONCLUSION The ischemic preconditioning and postconditioning are able to minimize the tissue injury in the intestines of rats that underwent the procedure of mesenteric ischemia and reperfusion.

Evaluation of ischemic postconditioning effect on mesenteric ischemia treatment: experimental study in rats

OBJECTIVE To assess the preconditioning and postconditioning effect on intestinal mucosal lesions in rats undergone mesenteric ischemia and reperfusion procedure. METHODS Thirty Wistar rats were studied and divided into three groups: Group A, 10 rats undergone mesenteric ischemia (30 minutes) and reperfusion (60 minutes); Group B, 10 rats undergone mesenteric ischemia and reperfusion preceded by ischemic preconditioning for three cycles of ischemia and reperfusion for two minutes each; Group C, 10 rats undergone mesenteric ischemia and reperfusion and, preceding the beginning of reperfusion, ischemic postconditioning was performed for three cycles of reperfusion and ischemia for two minutes each. Then, a segment of small intestine was resected for histological analysis. We assessed the results by Chiu et al. score and the statistical analysis was performed. RESULTS According to Chiu et al. score, the means of lesion degree were: In the group A, 3.5; Group B, 1.2; Group C, 1. The difference between group A with the groups B and C was considered statistically significant (P < 0.05). CONCLUSION Ischemic pre- and postconditioning were capable of minimizing - in a similar intensity - the tissue injury on the intestinal mucosa of rats undergone mesenteric ischemia and reperfusion process.

Terapêutica medicamentosa na isquemia e reperfusão mesentérica: revisão da literatura

Ate pouco tempo atras se acreditava que na isquemia mesenterica todas as alteracoes orgânicas desta afeccao eram devidas a obstrucao total ou parcial do fluxo arterial intestinal. Recentes descobertas quanto a fisiopatologia do processo de isquemia e reperfusao mesenterica demonstraram que os radicais livres, principalmente, atuam durante a reperfusao, levando a lesao tecidual muito mais importante do que as lesoes que ocorrem na fase de isquemia isoladamente. Assim, surge uma nova possibilidade terapeutica alem do tratamento cirurgico, em que uma determinada substância poderia atuar de modo a inibir ou minimizar a cascata de alteracoes no nivel celular que culminam na lesao e morte celular. Realizamos uma ampla revisao da literatura medica atual pelos bancos de dados LILACS e MEDLINE, visando verificar quais os farmacos estudados para este fim e os resultados obtidos nas pesquisas. Constatamos que inumeras substâncias tem sido avaliadas em estudos experimentais, em sua maioria utilizando ratos e a maioria nao apresentou resultados satisfatorios a ponto de permitirem seu emprego na pratica clinica; algumas, entretanto, apresentaram resultados promissores, necessitando ainda de novos estudos a fim de se descobrir uma substância que possa ser empregada em seres humanos em situacoes de isquemia e reperfusao mesenterica, a fim de se evitar tratamentos intervencionistas com altos indices de morbi-mortalidade.

Avaliação do pós-condicionamento isquêmico no tratamento da isquemia mesentérica: estudo experimental em ratos

OBJECTIVE To assess the preconditioning and postconditioning effect on intestinal mucosal lesions in rats undergone mesenteric ischemia and reperfusion procedure. METHODS Thirty Wistar rats were studied and divided into three groups: Group A, 10 rats undergone mesenteric ischemia (30 minutes) and reperfusion (60 minutes); Group B, 10 rats undergone mesenteric ischemia and reperfusion preceded by ischemic preconditioning for three cycles of ischemia and reperfusion for two minutes each; Group C, 10 rats undergone mesenteric ischemia and reperfusion and, preceding the beginning of reperfusion, ischemic postconditioning was performed for three cycles of reperfusion and ischemia for two minutes each. Then, a segment of small intestine was resected for histological analysis. We assessed the results by Chiu et al. score and the statistical analysis was performed. RESULTS According to Chiu et al. score, the means of lesion degree were: In the group A, 3.5; Group B, 1.2; Group C, 1. The difference between group A with the groups B and C was considered statistically significant (P < 0.05). CONCLUSION Ischemic pre- and postconditioning were capable of minimizing - in a similar intensity - the tissue injury on the intestinal mucosa of rats undergone mesenteric ischemia and reperfusion process.

Uso do propofol (2,6 diisopropilfenol) como inibidor da lesão tecidual na isquemia e reperfusão mesentérica: estudo experimental em ratos

PURPOSE: Evaluate the effects of propofol as inhibitor of tissue lesion in mesenteric ischemia and reperfusion in rats. METHODS: Forty rats Wistar were submitted to anesthesia and middle laparotomy. Intestinal ischemia was obtained by false ligature of cranial mesenteric artery by thirty minutes. Then, the tissue was reperfused for sixty minutes. The half of the animals received physiologic solution 0,9% 10 ml/kg/h (control group) by intravenous infusion; the other half received propofol 20 mg/kg/h by same way (propofol group). At the end, a segment of intestine was taken for histologycal analysis. The results were analyzed in agreement with CHIU et al 80 classification and the statistical analysis was done. RESULTS: In the control group was founded 5 rats with classification grade 2; 8 with classification grade 3; 3 with classification grade 4 and 4 rats with grade. In the propofol group was found 6 rats with classification grade 1; 11 with classification grade 2 and 3 with classification grade 3. The classification media was 3,3 for control group and 1,85 for the propofol group. The variation in the two groups was considered statistically significant (P < 0,05). CONCLUSION: The propofol minimize the tissue lesion in mesenteric ischemia and reperfusion in rats.

Effects of ischemic postconditioning on left ventricular function of isolated rat hearts

OBJECTIVE To assess the effects of ischemic postconditioning on left ventricular function in isolated rat hearts. METHODS Twenty-four Wistar rats were used. These hearts underwent perfusion by modified LANGERDORFF method and distributed into three groups: GI--control (n=8); GII--three cycles of postconditioning of 10/10s (n=8); GIII three cycles of postconditioning of 30/30s (n=8). After a 15 min stabilization period, all hearts underwent 20 min of global ischemia following 20 min of reperfusion. In the times 0 (control), 5, 10, 15 and 20 min of reperfusion, the heart rate (HR), the coronary flow (CoF), the systolic pressure, the (+dP/dt max) contractility and (-dP/dt max) velocity of relaxation were measured. Data were analyzed by ANOVA method followed by Tukeys test for differences between groups and P < 0.05 was considered significant. RESULTS The HR (bpm) decreased in all groups after 20 min of reperfusion without statistical differences among them (GI 232.5+36.8; GII 241.8+46.7; GIII 249.4+40.4;P>0.05). The same occurred with the systolic pressure (mmHg) (GI 132.6+49.3; GII 140.8+43.1; GIII 112.6+33.2; P>0.05), coronary blood flow (GI 18.5+4.6; GII 21.4+4.4; GIII 22.1+9.0; P>0.05) and -dP/dt max (mmHg) (GI 1490.6+512.0; GII 1770.4+406.6; GIII 1399.1+327.4; P>0.05). The +dP/dt max (mmHg) decreased significantly in all groups except in group II (GI 1409.0+415.2, GII 1917.3+403.1, GIII 1344.8+355.8) (GII vs GI, P= 0.04; GII vs GIII, P= 0.02). CONCLUSION The ischemic postconditioning by three cycles of reperfusion/ischemia of 10/10s demonstrated to be effective for preservation of the myocardial contractility in isolated rat hearts which had undergone 20 min of ischemia.

New technical approach for crossed papillopexy in mitral valve replacement surgery: short term results

OBJECTIVE: To present the crossed papillopexy technique and its initial results in the preservation of papillary muscles in mitral valve replacement and ventricular remodeling surgeries for heart failure (CHF). METHOD: Ten patients, 70% male, with ages between 15 and 75 years old (mean 44.4 ± 18.7 years old), suffering from rheumatic mitral valve disease (50%), mitral valve prolapse (10%) or dilated cardiomyopathy (40%), were studied. After opening the left atrium and adequate exposure of the mitral valve, the anterior leaflet already free of its annulus fixation was centrally divided and each half, with its cordae tendineae complex fixed to the commissure on the opposite side. Following this, mechanical (seven cases) or biological (three cases) prostheses were implanted using single sutures in the valve annuli, with reduction of the mitral valve annulus for better ventricular remodeling in CHF cases. RESULTS: All patients were discharged from hospital in good clinical conditions. Additionally all presented with great improvement in the cardiac performance at the end of the first month of follow-up, with significant reductions in the left ventricular and left atrium systolic diameters (p<0.05) and mean increases in the left ventricle ejection fraction of from 46.7 to 56.4 % (p<0.05). CONCLUSION: The crossed papillopexy technique in valve replacement surgeries for mitral valve lesions and CHF presented significant increases in the left ventricular function and improvement of ventricular remodeling in the studied postoperative period.

Percutaneous transluminal septal alcoholization for the treatment of refractory hypertrophic obstructive cardiomyopathy: initial experience in the Federal District

OBJECTIVE To analyze the efficacy of percutaneous transluminal septal alcoholization in the treatment of refractory obstructive hypertrophic cardiomyopathy (HOC). METHODS The patients were referred for alcoholization after Doppler echocardiography. Before and after alcoholization, the intraventricular pressure gradient was recorded. Alcoholization was performed with a 3mL injection of absolute alcohol through a coronary angioplasty balloon catheter. The procedure was concluded after a significant reduction or abolition of the pressure gradient. RESULTS Of 22 patients, 18 (81.8%) successfully concluded the procedure with a reduction in intraventricular pressure gradient at baseline (from 67.6+/-24.2 mmHg to 3.8+/-1.9 mmHg, p<0.005) and after extrasystole (from 110.4+/-24.2 mmHg to 9.6+/-2.6 mm Hg, p<0.005). A significant reduction in mean interventricular septal thickness (from 2+/-0.3 mm to 1.7+/-0.2 mm, p<0.005) and in peak pressure gradient (from 90.7+/-23.5 mmHg to 6.1+/-1.4 mmHg, p<0.005) was observed on Doppler echocardiography after 6 months, when all patients were in functional class I. The most frequent acute complication, present in 11% of the patients, was the need for definitive pacing implantation. Relapse of the symptoms and reappearance of the pressure gradient occurred in 16.6% of the patients. One patient (5.5%) died probably due to a diffuse coronary spasm prior to the procedure, and another died suddenly on late follow-up. CONCLUSION Percutaneous transluminal septal alcoholization is effective and safe in the treatment of HOC.

Comparative experimental study of myocardial protection with crystalloid solutions for heart transplantation

BACKGROUND There is a growing need to improve myocardial protection, which will lead to better performance of cardiac operations and reduce morbidity and mortality. Therefore, the objective of this study was to compare the efficacy of myocardial protection solution using both intracellular and extracellular crystalloid type regarding the performance of the electrical conduction system, left ventricular contractility and edema, after being subjected to ischemic arrest and reperfusion. METHODS Hearts isolated from male Wistar (n=32) rats were prepared using Langendorff method and randomly divided equally into four groups according the cardioprotective solutions used Krebs-Henseleit-Buffer (KHB), Bretschneider-HTK (HTK), St. Thomas-1 (STH-1) and Celsior (CEL). After stabilization with KHB at 37ºC, baseline values (control) were collected for heart rate (HR), left ventricle systolic pressure (LVSP), maximum first derivate of rise left ventricular pressure (+dP/dt), maximum first derivate of fall left ventricular pressure (-dP/dt) and coronary flow (CF). The hearts were then perfused at 10ºC for 5 min and kept for 2 h in static ischemia at 20ºC in each cardioprotective solution. Data evaluation was done using analysis of variance in completely randomized One-Way ANOVA and Tukeys test for multiple comparisons. The level of statistical significance chosen was P<0.05. RESULTS HR was restored with all the solutions used. The evaluation of left ventricular contractility (LVSP, +dP/ dt and -dP/dt) showed that treatment with CEL solution was better compared to other solutions. When analyzing the CF, the HTK solution showed better protection against edema. CONCLUSION Despite the cardioprotective crystalloid solutions studied are not fully able to suppress the deleterious effects of ischemia and reperfusion in the rat heart, the CEL solution had significantly higher results followed by HTK>KHB>STH-1.

Ischemia-reperfusion histopathology alterations of the rabbit intestinal wall with and without ischemic preconditioning

PURPOSE To evaluate the histopathology alterations of the intestinal mucosa of rabbits submitted to mesenteric artery ischemia and reperfusion with and without ischemic preconditioning. METHODS Two groups of ten male New Zealand white rabbits body (weight 2.2-3.0, average 2.5 kg). For mesenteric ischemia induction in all animals the small bowel and mesentery were cut 30cm and 60cm far from the gastroduodenal pyloric transition before the proximal mesenteric artery occlusion. In the Group 1 animals, the proximal mesenteric artery was occluded for 45 min with an atraumatic vascular clamp, followed by reperfusion for 30 min. In the Group 2 the 45 min ischemic phase was preceded by three cycles of ischemia (2 minutes each) alternated with three cycles of reperfusion (2 minutes each). For istopathology study small bowel biopsies were obtained before ischemia (control), after 45 min of mesenteric ischemia and at 30 min. of mesenteric artery reperfusion. RESULTS In the Group I animals, the followings histopathology grade results were observed: t1, mean 2,8; t2, mean 3,3. Using the Kruskal-Wallis non-parameter test, differences between t0 and t1 and t0 and t2 were significants (p<0.05), but not significant between t1 and t2 (p>0.05). In the Group 2 animals histopathology grade results were: t1 mean 2,6 and t2, mean 2,1. Differences between t0 and t1, t0 and t2 were significant (p<0.05). It was not observed differences (p>0.05) between results of t1 in both groups but histopathology injury observed in Group 1 t2 biopsies were higher (p<0.05) than observed in the same period (t2) of Group 2 animals. CONCLUSION Microscopic examination of the biopsies revealed significant evidence of preconditioning protection against small bowel wall ischemia-reperfusion injury.