The Journal of Thoracic and Cardiovascular Surgery, Vol 104, 1148-1147, Copyright © 1992 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Effect of an oxygen-enriched solution and multiple dosing of antegrade crystalloid cardioplegic solution on myocardial metabolism during coronary artery bypass graft operations
RS Downey, WS Weintraub, EL Jones, RB Conn and T Ash
Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, Ga. 30322.
The metabolic effect of excessive oxygenation and frequency of
administration of antegrade crystalloid cardioplegic solution was assessed
in 33 patients undergoing routine coronary artery bypass graft operations.
Four patient groups were designed in which the initial aortic root
injection was 1000 ml and then 100 ml administered through the vein grafts
after completion of each distal anastomosis. The groups were divided as
follows: group 1, single dose, normally oxygenated cardioplegic solution
infused via the aortic root; group 2, single dose, high oxygen content
cardioplegic solution infused via the aortic root; group 3, normally
oxygenated cardioplegic solution with additional 250 ml doses via the
aortic root every 20 minutes; group 4, high oxygen content cardioplegic
solution with additional 250 ml doses via the aortic root every 20 minutes.
In all groups myocardial mean septal temperature showed an immediate fall
to approximately 11 degrees C with the initial aortic root doses and then a
gradual rewarming to approximately 20 degrees C during the crossclamp
period (mean 58.6 minutes). Metabolic parameters measured or calculated
from the coronary sinus effluent were myocardial oxygen extraction, lactate
production, base deficit, inorganic phosphate, glucose, potassium, creatine
kinase (total and myocardial band fraction), and catecholamine production.
There was no statistically significant difference in any of these
determinations between each patient group. Furthermore, myocardial
recovery, myocardial performance, and postoperative recovery
characteristics were not different. We conclude that single or multidose
aortic root crystalloid cardioplegic solution (either oxygen enriched or
normally oxygenated) is equally effective in routine coronary artery bypass
graft operations when septal temperatures are maintained between 15 degrees
and 21 degrees C for a total arrest time of 60 minutes or less. In this
study, increasing the volume cardioplegic solution given in multiple doses
appeared to offer no significant metabolic or functional advantage in
patients without complications who had satisfactory left ventricular
function.
