Edgard Augusto Lopes

Evidence for superoxide radical-dependent coronary vasospasm after angioplasty in intact dogs.

BackgroundActive oxygen species can influence vascular tone and platelet activation through a variety of mechanisms. This study assessed the role of the superoxide anion, the hydroxyl radical, and hydrogen peroxide in vasoconstriction and mural thrombosis after coronary artery angioplasty in intact dogs. Methods and ResultsInjury was induced by inflation of a balloon catheter 50±6% above baseline arterial diameter; dogs were followed for 2 hours before death. Epicardial coronary diameters at arteriography and extent of thrombus deposition at serial histological sections were analyzed in controls (n =20) and in dogs pretreated with superoxide dismutase (SOD, a superoxide radical scavenger, n = 10); other dogs were pretreated with the hydrogen peroxide scavenger catalase (n =8), the iron chelator deferoxamine (n =6), or the hydroxyl radical scavenger 1,3-dimethyl-2-thiourea (n =9). Angioplasty-induced injury was similar among groups. After angioplasty, control dogs exhibited localized and persistent vessel constriction, which was maximal at the initial 5 minutes (28.9 + 6.3% diameter decrease versus baseline). Corresponding arterial diameters of SOD-treated dogs were 24–69% larger (95% confidence interval, p < 0.001) than controls at 5 minutes and, on average, 32% larger than controls thereafter (p < 0.01). Vasoconstriction was not prevented by the other treatments. The SOD dose used accounted for inhibition of zymosan-stimulated blood cytochrome c reduction versus baseline (7 + 3 versus 30±6 nmol/min/106 cells, respectively, p = 0.003); such inhibition occurred in no other group. Prevalence of mural thrombosis was similar among all groups, but large thrombi (>15% of lumen area) were absent in SOD-treated dogs, contrary to control group (p = 0.028); other groups were similar to control. In the absence of injury, SOD alone induced no change in coronary diameter, coronary blood flow, or platelet aggregation. ConclusionsThese data provide evidence implicating the superoxide radical in the genesis of vasoconstriction after coronary angioplasty in vivo. Such effects seem to be independent of its conversion to hydroxyl radicals and availability of hydrogen peroxide or catalytic iron complexes.

Percutaneous transluminal coronary angioplasty - Histopathological analysis of nine necropsy cases

From 1982 to 1984 nine of 300 patients undergoing transluminal coronary angioplasty died. The nine coronary arteries and one saphenous aorto-coronary by-pass graft affected by angioplasty were studied by light microscopy. The following types of lesions were found, frequently in association: rupture of the plaque, circumscribed or reaching to the intimal layer or extending beyond it, dissections (fissures) between arterial layers, intra-plaque haemorrhage, plaque emboli and thrombosis. In two cases the therapeutic approach was considered to be clinically and pathologically successful; the patients survived 24 h (case 6) and forty days (case 4). Case 6 which presented recent lesions indicative of success showed, in contrast with the other non-successful cases, rupture affecting not only the initimal layer but also deeper structures of the arterial wall. There were also more extensive fissures. Case 4 which presented late alterations indicative of success showed a plaque fracture whose borders were kept apart by fibrous tissue. In conclusion, we believe that angioplasty allows the re-establishment of arterial blood flow by provoking deep intimal and medial rupture producing a small fissure between the arterial layers and a widening of the lumen; in cases with good late results these alterations cicatrize leaving a wider arterial lumen.

Intramural coronary vessels in partial absence of the myocardium of the right ventricle

Abstract Partial absence of the right ventricular (RV) myocardium characterized by its replacement by adipose tissue, also known as RV displasia and RV myocardiopathy, has been reported in many patients. They are usually young adults with arrhythmia or sudden death 1 ; some cases have had progressive heart failure. 2 Recently microscopic lesions in the myocardial fibers have been demonstrated. 3 We present such a case in which we found alterations in the intramural coronary vessels that have not been described so far.

Nesidioblastosis Associated with Congenital Malformations of the Heart: Morphological and Immunohistochemical Study of 5 Necropsy Cases

Pancreatic tissue from 5 children with congenital heart disease (CHD) with morphological alterations of the endocrine components at autopsy were compared in a double-blind semiquantitative study, which included light microscopy and immunocytochemistry, to pancreatic tissue of 5 children of similar age but without CHD. Hyperplasia and hypertrophy of islets of Langerhans, scattered endocrine cells within the exocrinic acini, cluster of endocrine cells budding from ductular epithelium or within interlobular connective tissue, and hyperplasia of ductular epithelium were found to be present in the patients with congenital cardiac defects. The observed findings resembled those present in a surgically resected pancreas from a child with clinically overt nesidioblastosis. Although this study suggests a higher incidence of endocrine pancreas disturbances in certain types of CHD, the clinical significance of these morphological alterations will require further studies.

Bases experimentais da utilização da cardiomioplastia no tratamento da insuficiência miocárdica

A cardiomioplastia e uma tecnica que utiliza enxertos musculares esqueleticos, estimulados sincronamente ao coracao, para substituir, ou envolver o miocardio. O objetivo deste trabalho foi analisar as caracteristicas contrateis e a resistencia a fadiga do musculo grande dorsal normal e estimulado cronicamente, bem como avaliar a eficiencia da cardiomioplastia como metodo de suporte circulatorio. Treze caes foram estudados, apos condicionamento eletrico do musculo grande dorsal esquerdo, por periodo de 6 semanas. Sete deles foram submetidos a medida isometrica da forca exercida pelos musculos condicionados e pelos controles contralaterais e a estudo morfologico. Os parâmetros ideais de estimulacao foram semelhantes para os musculos normais e os condicionados. Os musculos condicionados, constituidos, predominantemente, de fibras de acao lenta, apresentaram uma forca de amplitude menor (-27%) e um tempo de contracao mais longo (+32%). Por outro lado, as curvas de fadiga dos musculos normais, constituidos de fibras mistas, mostraram a queda inicial da forca de contracao e valores estaveis, apos 30 minutos, inversamente proporcionais a frequencia das contracoes, resultando em um mesmo indice tensao-tempo (18 ± 2 kgF. seg/min). Ja os musculos condicionados apresentaram um desempenho estavel nas mesmas frequencias, mantendo um indice tensao-tempo elevado (68 ± 6 kgF. reg/min). Os outros 6 animais foram submetidos a cardiomioplastia, sendo estudados hemodinâmica e ecocardiograficamente, apos a inducao de disfuncao miocardica. Com a estimulacao sincrona do musculo esqueletico, observou-se a elevacao do indice cardiaco em 36 ± 4% (p<0,01), associada a queda da pressao capilar pulmonar. O aumento da fracao de ejecao foi documentado (51 ± 3%), inclusive quando o enxerto foi colocado apenas sobre o ventriculo esquerdo (p < 0,01). Em conclusao: 1) os musculos esqueleticos sao capazes de manter atividade semelhante ao trabalho cardiaco, com um desempenho que depende de sua capacidade aerobica; 2) a estimulacao cronica leva a transformacao adaptativa das fibras musculares, aumentando a sua capacidade de trabalho aerobico; 3) a cardiomioplastia pode ser um metodo alternativo, no tratamento da insuficiencia miocardica, mesmo quando e possivel apenas o envolvimento parcial do coracao pelo enxerto.

Obstrução da via de saída de ventrículo esquerdo por prótese mitral: apresentação de seis casos

From January/1982 to March/1984, 170 high profile bovine pericardium bioprostheses were implanted in the INCOR (Instituto do Coracao), Hospital das Clinicas, Faculdade de Medicina da Universidade de Sao Paulo (FMUSP). Hospital mortality amongst these patients was 7.1%. Anatomopathological studies identified five cases in which obstruction of the left ventricle outlet occurred after substitution of the mitral valve. Based on this experience, the indication of a hemodynamic study on the first postoperative day of a patient with an unexplained low cardiac output made it possible to identify obstruction of the left ventricle valve outlet in such patients, with resubstitution of the valve and a satisfactory evolution of the case. In this report we relate the six cases in detail and discuss the causes of the obstruction of the outlet in mitral valve substitutions.

Ação da cardioplegia na proteção miocárdica: estudo experimental através das réplicas de criofraturas

Evaluation of myocardial protection by cardioplegic solutions and hipothermia in anoxic hearts. An experimental study. This investigation was performed in a group of 20 dogs submitted to myocardial anoxia by cross-clamping of the ascending aorta for sixty minutes under extracorporeal circulation, followed by reperfusion for 360 minutes. Ultrastructural changes of the myocardium were studied. The animals were divided into 4 groups of 5 dogs each. In the first group (control), myocardial anoxia was induced in normothermia and no cardioplegic solution was administered. In the second group, the body temperature was reduced to 28oC before the onset of myocardial anoxia, and no cardioplegic solution was used. In the third and fourth groups, in addition to 28oC systemic hypothermia, coronary infusion of 4oC cardioplegic solutions were performed immediately and after 30 minutes of clamping of the aorta. The cardioplegic solutions utilized have NaCl, KCl, CaCl2, Lidocaine, Verapamil, NaHCO3, MgSO4 and the infusion vehicle was 5% glucose solution in Group III, and blood in Group IV. Biopsies for freeze-fracture replication were obtained from the anterior wall of the left ventricle, before and after 60 minutes of myocardial anoxia, and 360 minutes after reperfusion. The alterations in sarcolemma and celular organeles due to anoxia or myocardial reperfusion was observed, specially through the diminution and aggregation of intramembranous particles in its P surface. We may conclude that both cardioplegic solutions used, associated to hipothermia, protect efficiently the myocardial cells against anoxia. It was not possible, however, to demonstrate any superiority of the blood solution over an acellular solution. Systemic hypothermia as a single method was not sufficient to offer good protection to the anoxic myocardium. The animals of Group I (control) showed severe compromise of the structure and function of the myocardium.