RESUMO
The critical phase during cardiosurgical procedures is weaning the diseased heart from the ECC (extracorporeal circulation). Post-ischaemic heart failure sometimes requires the administration of inotropic and/or vasconstrictive agents. The natriuretic peptides influence pre- and after-load through their natriuretic, diuretic and vasodilating actions. To date, there are only a few reports describing the therapeutic effect of BNP (brain natriuretic peptide) administration during cardiosurgical procedures. The aim of the present study was to evaluate the effect of BNP administration following ECC in an animal model. Surgery was performed on 20 pigs using ECC. A 30-min ischaemic episode was simulated. Following de-clamping, BNP was administered to the BNP group (n=10) by an i.v. (intravenous) bolus at 0.3 microg x kg(-1) of body weight x min(-1), followed by an infusion at a rate of 0.015 microg x kg(-1) of body weight x min(-1) for 60 min. The animals in the control group (n=10) received a saline solution instead of BNP. Haemodynamic and clinical chemistry parameters as well as the amount of catecholamines that were required were measured. All of the animals in the BNP group had a significantly better cardiac output and cardiac index at the end of the experiment. Seven out of 10 animals from the control group required catecholamines, whereas only one animal from the BNP group did. Creatine kinase levels were significantly lower in the BNP group. Systemic vascular resistance was markedly lower in the BNP group. In conclusion, administration of BNP is highly effective in treating post-ischaemic heart failure following ECC. Haemodynamics are greatly improved, and there is almost no need for pharmacological support.