The Annals of Thoracic Surgery, Vol 32, 75-79, Copyright © 1981 by The Society of Thoracic Surgeons
The optimal potassium concentration in cardioplegic solutions
JH Rousou, RM Engelman, WA Dobbs and S Lemeshow
High-energy phosphates provide a sensitive index of myocardial
preservation. This experiment was designed to use this index in order to
assess the efficacy of various potassium concentrations in a crystalloid
cardioplegic solution in protecting the myocardium during hypothermic
ischemic arrest. The in vivo ischemic pig-heart model was used, measuring
left ventricular levels of adenosine triphosphate (ATP) before, during, and
after a two-hour arrest period and after 30 minutes of reperfusion.
Thirty-eight animals were divided into seven groups of 5 to 6 animals each.
Each group received a different potassium concentration in the cardioplegic
solution, namely, 5, 10, 15, 20, 25, 30, and 35 mEq/L. The results were as
follows: the ATP moiety was best preserved during ischemia and reperfusion
in the 15 mEq/L group, while it remained significantly lower in the 5 mEq/L
group. The 10, 20, 25, 30, and 35 mEq/L groups showed an intermediate range
of ATP preservation. We conclude from these results that cardioplegic
solutions containing 5 mEq/L of potassium seem to be inadequate for
myocardial preservation during ischemic arrest; that solutions with 15
mEq/L of potassium may offer the best myocardial protection of all
concentrations tested; and that solutions with potassium concentrations of
15 and 35 mEq/L are significantly better than normokalemic (5 mEq/L)
cardioplegic solutions.
