The Annals of Thoracic Surgery, Vol 35, 372-379, Copyright © 1983 by The Society of Thoracic Surgeons
Myocardial blood flow and oxygen consumption in the empty-beating, fibrillating, and potassium-arrested hypertrophied canine heart
JD Sink, RC Hill, DE Attarian and AS Wechsler
Myocardial oxygen consumption and blood flow distribution were examined in
severely hypertrophied canine hearts in the empty-beating, fibrillating,
and pharmacologically arrested states. Hypertrophy was produced using a
subcoronary valvular aortic stenosis model that mimics the clinical
situation of aortic valvular stenosis. Oxygen content of the total coronary
sinus collection was compared with a large volume arterial sample using a
Lex-O2-Con-TL analyzer, which had been validated by the Van Slyke-Neill
method. Transmural blood flow was measured in each state using
microspheres, and perfusion pressure was maintained at 80 mm Hg. Oxygen
consumption in the empty-beating hypertrophied heart was found to be the
same as that previously reported for normal hearts. Blood flow was evenly
distributed in the empty-beating heart, with an endocardial/epicardial
ratio of 0.99 +/- 0.15 (SEM) milliliters per minute per gram of left
ventricular weight. Oxygen consumption failed to increase significantly
with fibrillation; however, blood flow distribution favored the
subepicardium, suggesting that oxygen consumption determinations in the
fibrillating hypertrophied heart may not accurately reflect metabolic
demand. Basal oxygen consumption of the hypertrophied heart as determined
by the potassium-arrested, blood-perfused model was the same as that
previously described for normal hearts. Blood flow during potassium arrest
favored the subendocardium (endocardial/epicardial ratio = 1.14 +/- 0.27
ml/min/gm LV weight).
