INTRODUCTION: The action of a cardioplegic solutions with lidocaine and potassium. Was studied experimentally in dogs. MATERIAL AND METHODS: Fourteen dogs, divided en two groups, were operated. The group 1 was composed of 5 dogs, who were submitted to 120 minutes of myocardial anoxia, through cross clamping of the ascending aorta under cardiopulmonary bypass, without any myocardial protection. The group 2 were treated in the same way, but received cardioplegic protection. The technique of cardioplegia consisted of two phases: a) Induction phase the induction was achieved by the injection of 100mg of lidocain and 2.5 mEq of potassium, diluted in 60 ml of blood from the arterial line. This first injection was in bolus. After this, blood was injected from the arterial line during 30 seconds. The heart immediately had an arrest. b)The second phase was called maintaining phase. This phase consisted of repeated injections of blood from the arterial line, during 30 seconds each, and repeated every 20 minutes during the ischemic period. RESULTS: All animals of this protected group survived after the release of the cross clamping of the aorta and all the dogs of the non protected group died after the end of the ischemic time. Echocardiographic evaluation were performed in 3 different moments of the experiment. The first was control, before cardiopulmonary bypass and the measures of delta D and ejection fraction were normal in all animals. The second was done about one hour after the reperfusion, in the group 2 animals. This measurement showed a decrease of 30% when compared with the control values. The third echocardiographic evaluation was done 5 hours after the end of the perfusion and showed a restoring to normal values in all 9 dogs of the group 2 dogs. All 14 hearts were studied with optical and electronic morphological exams. The group 1 dogs showed intense myocardial damage, while the group 2 animals showed inexpressive morphological findings. CONCLUSION: It was concluded that the cardioplegia technique utilized in group 2 animals was effective in myocardial protection action, with good echocardiographic performance after perfusion and almost no morphological alterations in anatomopathological studies.
Cardioplegic sulutions; Lidocaine; Potassium
