The Annals of Thoracic Surgery, Vol 28, 281-289, Copyright © 1979 by The Society of Thoracic Surgeons
The importance of hyperkalemia in a cold perfusion solution: a correlative study examining myocardial function, metabolism, tissue gases, and substrates
WH Heydorn, WY Moores, J Mack and W Dembitsky
Twenty-four pigs were studied to assess the effect of potassium in a
cardioplegic solution on the ability of the swine myocardium to maintain
functional and metabolic integrity following induced ischemia. The pigs
were evaluated on total and right heart bypass with measurement at
normothermia and after a one-hour intervention of stroke volume (SV),
coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and
lactate extraction. Myocardial tissue gases (PmO2 and PmCO2) were
continuously monitored and, at the conclusion of the procedure tissues were
analyzed for adenosine triphosphate (ATP). There were five interventions:
(1) hypothermic perfusion (28 degrees C) (Group 1); (2) hypothermic
ischemia (28 degrees C) (Group 2); and hypothermic ischemia with a
cardioplegic solution (nonlactated Ringer's solution, pH 7.4, 4 degrees C)
using (3) normokalemia (4 mEq of potassium chloride/L, 300 mOsm/L (Group
3), (4) hyperkalemia (43 mEq of KCl/L, 390 mOsm/L) (Group 4), and (5)
normokalemia with increased osmolarity (3.6 mEq of KCl/L, 400 mOsm/L)
(Groups 5). A significant decrease in SV and elevation in peak PmCO2 were
seen in all groups subjected to ischemia except those protected with
hyperkalemic solution. We conclude that the presence of hyperkalemia in a
cold root perfusion solution provides better myocardial protection than
cold root perfusion alone. Furthermore, potassium arrest appears to be more
protective than coronary perfusion at 28 degrees C.