Glucose level and myocardial recovery after warm arrest.
BACKGROUND
During induced cold ischemia for cardiac operations, increasing glucose concentration is not thought to enhance myocardial protection and may detrimentally affect recovery. However, during "warm aerobic" arrest, increased glucose availability as substrate could enhance postischemic metabolic and functional recovery, as during and after ischemia, myocytes shift preference for substrate from fatty acids to glucose. Unfortunately, hyperglycemia may also increase patient susceptibility to neurologic injury.


METHODS
This experiment was designed to study the optimal dose of glucose and its effect on function during warm arrest. Isolated, retrograde-perfused rabbit hearts received multidose cardioplegia containing increasing concentrations of glucose, from 0 to 88 mmol/L, and underwent 120 minutes of "warm" 34 degrees C global ischemia. Osmolarities were adjusted equivalently.


RESULTS
After 34 degrees C ischemia, hearts treated with 5 to 88 mmol/L glucose showed significantly better functional recovery than those treated with 0 to 1 mmol/L glucose. However, the addition of 22 mmol/L glucose demonstrated optimal recovery with no further incremental enhancement with more glucose. Additional hearts receiving 0 or 22 mmol/L glucose had high-energy phosphates, lactate, CO2, and pH measured. The 22 mmol/L glucose hearts demonstrated active metabolism and significantly better recovery of high-energy phosphate levels than controls.


CONCLUSIONS
Increasing glucose level modestly during warm arrest enhanced recovery, but profound hyperglycemia did not incrementally improve this effect, mandating a cautious use of glucose.
Ning
X H
XH
Section of Thoracic Surgery, University of Michigan Medical Center, Ann Arbor, USA.
Childs
K F
KF
Bolling
S F
SF
D000227:Adenine Nucleotides; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004734:Energy Metabolism; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D006324:Heart Arrest, Induced; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D009711:Nucleotides / Q000378:metabolism; D010101:Oxygen Consumption; D010710:Phosphates / Q000378:metabolism; D011817:Rabbits; D013696:Temperature
D000227:Adenine Nucleotides; D009711:Nucleotides; D010710:Phosphates; D019344:Lactic Acid; D005947:Glucose