Myocardial protection in the occlusion/reperfusion dog model: the role of ischemic necrosis vs reperfusion injury

The present study was designed to assess the possbility of maximizing the effects of reperfusion by the association of the calcium channel blocker, verapamil and the iron chelator deferoxamine, to delay necrosis and avoid reperfusion injury. Sixty-four mongrel dogs (15 ñ 1.1 (SD)Kg) were successfully subjected to 24 h of reperfusion following 90-min occlusion of the left anterior coronary artery. ECG and arterial presure were monitored. The risk area (RA; percent left ventricle (LV)) was determined by the infusion of Evans blue into the aortic root and the area of necrosis (AN; per cent RA) by triphenyltetrazolium chloride staining. Myocardial presevation was defined as per cent RA not necrosed calculated as (RA - AN)/RA x 100.RA was similar in all dogs, i.e., 33 ñ 2 per cent LV (SD). There were no differences in arterial pressure, heart rate or double product among groups. Myocardial preservation was 60 ñ 13 per cent RA in 9 control dogs submitted to reperfusion only (group C), and 58 ñ 18 per cent RA in 17 dogs treated with deferoxamine (500 mg, iv), 30 min before reperfusion (group DF). Verapamil (0.2 mg/Kg, iv) was given alone 15 min after occlusion to 15 dogs (group VP), followed by prereperfusion deferoxamine to 16 dogs (goup VP + DF) and in two doses after occlusion and 15 min before reperfusion in 7 dogs (group VP + VP). Myocardial preservation was greater in the latter groups when compared to controls, namely 76 ñ 13 per cent RA in group VP, 74 ñ 11 per cent in group VP + DF and 73 ñ 9 per cent in group VP + VP (P = 0.04 vs group C., ANOVA). The data suggest that mechanism underlying this beneficial effect is mainly related to the retardation of nectosis progression. O2 free radicals or Ca2+-induced reperfusion injury do not play a major role

Balloon-induced endothelial denudation promotes deep injury of the arterial wall

To investigate the cellular reactions to arterial injuries and the influence of a cholesterol-rich diet, 18 rabbits underwent endothelial denudation of the abdominal aorta with a balloon catheter. Fourteen animals were fed a 2% cholesterol diet and 4 were fed normal rabbit chow for 8 weeks. In the cholesterolfed group, 6 animals had only the expected intimal lesions; however, 8 animals exhibited different degrees of balloon=induced medial layer injury, with fibrous healing. Similarly, in the control rabbits, 1 had intimal lesions and 3 had both intimal and medial layer lesions. We conclude that removal of the endothelium with a balloon catheter prometes arterial wall injury deeper than expected. This unexpected result could influence the effect of interventions usually employed in experimental atherosclerosis

Ultraestrutura do miocardio ventricular no paciente uremico - estudo de 11 casos com biopsia do coracao. / Ultrastructure of ventricular myocardium in uremic patients - study of 11 cases with heart biopsy

Ultraestrutura do miocardio ventricular no paciente uremico. Estudo de 11 casos com biopsia do coracao. A miocardiografia uremica tem sido um entidade discutida na literatura. Em 11 pacientes uremicos mantidos em dialise foi feita biopsia endocardica de ventriculo direito por agulha, atraves de via endovenosa, sendo o material analisado por microscopia eletronica.Foram encontradas alteracoes em todos os casos, com intensidade e extensao variaveis para cada paciente, representadas por: aumento do numero de mitocondrias (8 casos) do reticulo sarcoplastico 8, hipertrofia do nucleo 6, presenca de lipofuscina 6, deposicao de calcio em mitocondria 5, edema intracitoplasmatico 5, vacuolos de gordura 3 degeneracao miofibrilar 1.Em conclusao verificou-se dano real a fibra miocardica, nao dependente de hipertensao ou insuficiencia cardiaca. Isto sugere que em pacientes uremicos, seja por disturbio metabolico, seja por acao toxica de algum elemento, ocorre uma verdadeira miocardiopatia secundaria, semelhante a vista em outras condicoes que agridem o miocardio, mesmo em pacientes sem manifestacoes clinico-laboratoriais

Valvotomia pulmonar transvenosa com raios laser / Transvenous pulmonary valvectomy with laser rays

Foram estudados oito cäes mestiços, com pesos variáveis entre 12 e 15 Kg, submetidos à anestesia geral, toracotomia lateral e pericardiotomia longitudinal. Após ligadura da veia ázigos, as veias cavas anterior e posterior foram isoladas por cadarços de algodäo em torniquetes. Com técnica de bloqueio do retorno venoso, a artéria pulmonar foi aberta e as comissuras de sua valva suturadas, produzindo estenose pulmonar. A artéria pulmonar fou suturada e o retorno venoso liberado, assumindo os animais novo equilibrio hemodinâmico. Um cateter especial de angiocardiografia para aplicaçäo endocavitária de Laser (modelo Armelin e col.) foi introduzido na via de saida do ventrículo direto (por via transparietal em quatro casos e por cateterismo transvenoso-femoral nos demais). O laser foi aplicado na valva pulmonar obstruída até o desaparecimiento do gradiente pressórico estabelecido com à estenose pulmonar. Estudos hemodinâmicos e anatomopatológicos confirmaram a eficiência do método na desobstruçäo da estenose pulmonar