RESUMEN
BACKGROUND: The need for muscle relaxants in general anesthesia in different surgeries including cardiac surgeries, and the type of relaxant to be used considering its different hemodynamic effects on patients with heart disease can be of considerable importance. In this study, the hemodynamic effects of two muscle relaxants, Cisatracurium and Atracurium in patients whit low function of left ventricle who are candidate for open heart surgery have been considered. METHOD: This study has been designed as a randomized prospective double-blind clinical trial. The target population included all adult patients with heart disease whose ejection fraction reported by echocardiography or cardiac catheterization was 35% or less before the surgery, and were candidate for open heart surgery in Shahid Rajaei Heart Center. Taking into account the inclusion and exclusion criteria, the patients were randomly placed in two groups of 30 people each. In the induction stage, all the patients received midazolam, etomidate, and one of the considered muscle relaxant, either 0.2 mg/kg of cisatracurium or 0.5mg/kg of Atracurium within one minute. In the maintenance stage of anesthesia, the patients were administered by infusion of midazolam, sufentanil and the same muscle relaxant used in the induction stage. The hemodynamic indexes were recorded and evaluated in different stages of anesthesia and surgery as well as prior to transfer to ICU. RESULTS: In regard with descriptive indexes (age and sex distributions, premedication with cardiac drugs, ejection fraction before surgery, basic disease) there was no statistically significant difference between the groups. CONCLUSIONS: The significant difference of hemodynamic indexes between the two groups of this study, and the need for hemodynamic stability in all stages of surgery for patients with low function of left ventricle who are candidate for open heart surgery, proves that administering Cisatracurium as the muscle relaxant is advantageous and better.