Variação do debito cardiaco na estimulação artificial em ponta do ventriculo esquerdo, ponta do ventriculo direito e biventricular : estudo experimental em porcos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The experimental models admit the study of the artificial pacemakers in heart physiological phenomena and its correlation with the clinical practice. The purposes of this work were to pattern the technique of production of complete experimental AV block and to study the variation of the cardiac output in the sinus rhythm, in the AV block and with cardiac pacing in the apex of the RV, in the apex of the LV and in the biventricular pacing. At the same time, we also studied the variation of the stimulation threshold, the R wave amplitude, the electrical impedance between the electrode and the cardiac muscle and the variation of the length of the QRS complex. They were studied swine, with supposedly normal heart, to get complete experimental AV block by using thoracotomy with longitudinal externotomy without atriotomy by chemical necrosis of the conduction system by a 40 % formaldehyde solution injection. The cardiac output was measured by a thermo-dilution technique. The superficial E.K.G. registers were made in deviations D1, D2 and D3 with DMS1000 (Biotronik) device. The epicardial electrodes were model ELC-35 (Biotronik Gmbh). The stimulation was made with ERA300 (Biotronik) device in the VOO mode with 5 V of amplitude and 1 ms of length and the stimulation frequency was similar to that one found in the sinus rhythm in the open thorax. It was obtained complete AV block in all of the studied animals. The C.O., in this situation, was reduced a lot and it returned to the sinus rhythm level with all the stimulation modes. The threshold and R amplitude in apex of the RV and the apex of the LV were statistically equals; however, the electrical impedance of the LV was statistically higher than that one in the apex of the RV. It was observed a greater shortening of the length of the QRS complex with in the electrical artificial stimulation in the apex of LV and in the biventricular stimulation with negative electrodes in the apex of the LV and positive electrodes in the apex of the RV

ASSUNTO(S)

cirurgia experimental marca-passo artificial (coração) bloqueio cardiaco

ACESSO AO ARTIGO

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