title: Protection of myocardial function not enhanced by high concentrations of potassium during cardioplegic arrest.
abstract: Myocardial performance was evaluated intraoperatively in 20 patients undergoing myocardial revascularization when hypothermic potassium cardioplegic arrest was used. High concentrations of potassium (20 mEq/L) were compared to normal concentrations of potassium (5 mEq/L) in hypothermic cardioplegic solutions. The cardioplegic arrest period averaged 53 +/- 3 minutes in the high potassium group and 54 +/- 4 minutes in the low potassium group, Intraoperative calculation of ejection fraction and end-diastolic volume was accomplished by the technique of radiocardiography. All data were grouped according to end-diastolic volume index (EDVI) for both high (HK) and low (LK) potassium comparisons. Comparisons between high and low potassium groups demonstrated no significant differences in ejection fraction (HK = 66%, LK = 61%), cardiac index (HK = 2.74 L/min/m2, LK = 3.0 L/min/m2), stroke work (HK = 36 gm.m/m2, LK = 30 gm.m/m2), oxygen consumption as measured by left heart double product (HK = 9,438; LK = 9,209), and myocardial compliance (HK = 2.8 cc/torr, LK = 4.2 cc/torr at the post-cardioplegic arrest period). The role potassium plays in producing a rapid cardiac arrest is well accepted. Its protective effect on the preservation of high-energy phosphate stores is postulated, but its addition to perfusion hypothermia does not appear to enhance the protective effect observed with perfusion hypothermia alone.
mesh_terms: D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D003971:Diastole / Q000187:drug effects; D006324:Heart Arrest, Induced / Q000379:methods*; D006349:Heart Valve Diseases / Q000601:surgery; D006801:Humans; D007036:Hypothermia, Induced; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D009204:Myocardial Revascularization; D010101:Oxygen Consumption / Q000187:drug effects; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D013318:Stroke Volume / Q000187:drug effects; D013997:Time Factors
chemical_list: D011188:Potassium