The Annals of Thoracic Surgery, Vol 51, 620-629, Copyright © 1991 by The Society of Thoracic Surgeons
Oxygenated cardioplegia: the metabolic and functional effects of glucose and insulin
JB Steinberg, NE Doherty, NA Munfakh, GA Geffin, JS Titus, DC Hoaglin, AG Denenberg and WM Daggett
Department of Surgery, Massachusetts General Hospital, Boston 02114.
Reports differ as to the efficacy of glucose and insulin as cardioplegic
additives. Although deliberate oxygenation of crystalloid cardioplegic
solutions improves myocardial protection, little is known about the
protection afforded by glucose and insulin in such oxygenated solutions. In
the isolated working rat heart, we studied the addition of oxygen, glucose,
and insulin, separately and together, to a cardioplegic solution. The
solution was equilibrated with O2 or N2, with glucose added as a substrate
or sucrose as a nonmetabolizable osmotic control, with or without insulin.
Hearts were arrested for 2 hours at 8 degrees C by multidose infusions.
Oxygenation decreased lactate production and improved high-energy phosphate
and glycogen preservation during arrest, prevented ischemic contracture,
and improved functional recovery. The addition of glucose to the oxygenated
solution increased the level of adenosine triphosphate at end-arrest from
10.5 +/- 0.5 to 13.9 +/- 0.6 nmol/mg dry weight and glycogen stores from
18.7 +/- 2.5 to 35.7 +/- 5.5 nmol/mg dry weight. The further addition of
insulin did not better preserve these metabolites. Improvements in
functional recovery due to glucose or insulin in the oxygenated solution
attained statistical significance when both additives were included.
Glucose increased lactate production significantly only when the solution
was nitrogenated. Insulin added to the nitrogenated glucose-containing
solution increased adenosine triphosphate and glycogen levels after 1 hour
of arrest; and, although insulin did not prevent ischemic contracture from
developing during the latter part of arrest with profound depletion of
these metabolites, functional recovery was improved. The mechanism of
improved functional recovery by insulin is not clear.(ABSTRACT TRUNCATED AT
250 WORDS)
