Previous work in this laboratory has shown that an occlusive thrombus (O.T.) induced.
the left anterior descending coronary artery (L.A.D.) of dogs, by the placement of
a segment of magnesium-aluminum wire (M.A.W.) in the lumen of the artery, is associated
with the development of full thickness infarct (F.T.I.). Incomplete (mural) thrombus
is associated with focal areas of ischaemic damage, mainly sub-endocardial, in the
myocardium of the antero-lateral left ventricle. A 1.0 cm. length of M.A.W., shaped
in the form of a tennis racquet, was placed by cardiac catheterization in the proximal
L.A.D. of 30 mongrel dogs. Ten dogs received low dose aspirin (L.D.A.); (14 or 29
mgm/Kg daily in a single dose). Ten dogs received high dose aspirin (H.D.A.); (100
mgm/Kg daily in divided doses). Treatment was begun one day before operation and continued
until death or killing. Ten control dogs received no drug. All control dogs died within
3 days of operation. Five had O.T. and F.T.I. The remainder showed focal ischaemic
myocardial damage. None of the L.D.A. group died. At autopsy 3 or 4 days after operation,
none had O.T. or F.T.I. In the H.D.A. group 3 died; 4 had O.T. and F.T.I. Thus L.D.A.
provided significant protection from death, O.T., and F.T.I. H.D.A. provided some
(P <0.005) but less protection from death but did not significantly affect the incidence
of O.T. or F.T.I. Supported by Ontario Heart Foundation Grant T15-7.
