Circulation, Vol 54, 647-653, Copyright © 1976 by American Heart Association
ML Marcus, RJ Tomanek, JC Ehrhardt, RE Kerber, DD Brown and FM Abboud
The quantitative relationship between abnormalities seen on technetium- 99m
pyrophosphate (99mTc-PYP) infarct scintigrams and the size of the
myocardial infarction is unclear. We evaluated two possible determinants of
99mTc-PYP accumulation: myocardial perfusion measured with 7-10 mu
microspheres and the extent of necrosis determined histologically.
Hemodynamics and myocardial perfusion to small segments of the left
ventricle were measured prior to, 5-10 min, and 44-48 hours following
sudden occlusion of the left anterior descending coronary artery in ten
awake dogs. 99mTc-PYP was injected i.v. following the third injection of
microspheres and the animals were killed 2 hours later. The important
findings were as follows: 1) there is a close relationship between the
extent of myocardial necrosis observed and the perfusion of segments 5-10
min following coronary occlusion; and 2) that segmental myocardial
perfusion is an important determinant of 99mTc-PYP accumulation by
myocardial segments which contain areas of necrosis. Although the present
data preclude statistical analysis of the relationship between the level of
necrosis in a segment and the accumulation of 99mTc-PYP by that segment,
the two do not appear to be related, a finding which would discourage use
of intensity of 99mTc-PYP images for infarct size. The distribution of an
abnormality on the scintigram may provide an estimate of infarct size.
However, the geometry of the infarct and the resolving power of the
scanning equipment will significantly limit this in many clinical
situations.
ARTICLES
Relationships between myocardial perfusion, myocardial necrosis, and technetium--99m pyrophosphate uptake in dogs subjected to sudden coronary occlusion