Relation of stroke and cardiac indices to serum catecholamines following open heart surgery.

Serum catecholamines (epinephrine, dopamine and norepinephrine) were measured two, four and six hours after open heart surgery. The ratios of stroke index (SI) and cardiac index (CI) to catecholamines (CA) were determined. Patients studied consisted of 27 with congenital and 14 with acquired heart disease. Extracorporeal circulation (ECC) time was longer than 90 minutes in 17 and shorter in 24 patients. SI and CI diminished in elder patients with congenital disease (Group Cg-ad), patients with acquired disease (Group Ac) and patients with a longer ECC time (Group L). Therefore, elder age and/or longer ECC time seems to be responsible to the lower indices. However, the ratios of the indices to CA showed that the lower indices indicated the poor response of the myocardium to CA in Group Ac and Group L. The response was larger in Group Cg-ad and the lower indices were related to lower serum CA level. It was concluded, therefore, that the indices of stroke volume and cardiac output had inverse correlation to ECC time, but not to age, namely, prolonged ECC compromised more severely the myocardium and resulted in the poor response of the myocardium to CA. Subsequently, to compensate for the poor response, serum CA levels were elevated probably to maintain due SI and CI in patients with prolonged ECC.