The Journal of Thoracic and Cardiovascular Surgery, Vol 97, 43-49, Copyright © 1989 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Comparison of the metabolic response of the hypertrophic and the normal heart to hypothermic cardioplegia. The effect of temperature
M Rabinov, XZ Chen and FL Rosenfeldt
Baker Medical Research Institute, Melbourne, Australia.
The aim of this study was to test for metabolic differences in the response
of hypertrophic and normal hearts to hypothermic cardioplegia. Hypertrophic
dog hearts and normal control hearts were subjected to 6 hours of
hypothermic cardioplegia with the St. Thomas' Hospital solution. Levels
before arrest of subepicardial and subendocardial adenosine triphosphate,
creatine phosphate, and lactate in eight hypertrophic hearts were the same
as those levels in 12 normal hearts. In hypertrophic hearts, but not in
normal hearts, the induction of arrest was slow and was associated with an
11% increase in adenosine triphosphate levels, a 59% decrease in creatine
phosphate levels, and a 12-fold increase in lactate levels. Seven
hypertrophic hearts and eight normal hearts were studied during 6 hours of
arrest and showed no further differences in metabolic response. Reducing
the myocardial temperature from 20 degrees C to 12 degrees C slowed the
rate of depletion of adenosine triphosphate and the rate of accumulation of
lactate in both groups. We conclude that in the nonfailing, severely
hypertrophic heart, levels before arrest of high-energy phosphates and
lactate are normal, but that marked biochemical changes may occur if the
induction of arrest is prolonged because of underdosing with cardioplegic
solution. Cooling from 20 degrees C to 12 degrees C improves myocardial
preservation in both hypertrophic and normal hearts.
