In order to supply blood to the body, the heart muscle must pump harder than normal, leading to a thickened, overworked heart.
(the heart muscle; must pump harder; ) Context(the heart muscle must pump harder,List([38, 71))):(the heart muscle; must pump harder leading; to a thickened)
the heart muscle must pump harder,List([38, 71))
the heart muscle the heart muscle
must pump harder must pump harder leading
to a thickened