The Annals of Thoracic Surgery, Vol 32, 536-545, Copyright © 1981 by The Society of Thoracic Surgeons
Limitations of potassium cardioplegia during cardiac ischemic arrest: a phosphorus 31 nuclear magnetic resonance study
AC Pernot, JS Ingwall, P Menasche, C Grousset, M Bercot, M Mollet, A Piwnica and ET Fossel
Cold K+ cardioplegia is commonly used to preserve the myocardium during
surgical ischemia. Since the K+-induced membrane depolarization could cause
a Ca2+-mediated breakdown of adenosine triphosphate, this study compared
the influence of different electrolytes on high-energy phosphate metabolism
during cardioplegic arrest phosphate metabolism during cardioplegic arrest
and subsequent recovery of mechanical function. An isolated working heart
was subjected to hypothermic ischemia for one hour. Metabolic studies were
assessed on phosphorus 31 nuclear magnetic resonance (NMR). Results show
that (1) K+ cardioplegia is harmful when the Ca2+ content is equal to 2
mEq/I; (2) deleterious effects of K+ are markedly reduced by lowering the
Ca2+ content; (3) the most adequate preservation is provided by a
Mg2+-rich-Ca2+-poor perfusate; (4) this protection is not enhanced by
addition of K+. Finally, 31P NMR appears particularly appropriate for
evaluating myocardial protection techniques since it allows noninvasive
serial monitoring of high-energy phosphate content and subsequent
correlation with functional recovery after ischemia.