Quoting from _Robbins Basic Pathology 9th ed.
Thrombi are focally attached to the underlying vascular surface and tend to propagate toward the heart; thus, arterial thrombi grow in a retrograde direction from the point of attachment, while venous thrombi extend in the direction of blood flow.
What’s the underlying mechanism of this retrograde propagation? Shouldn’t the blood flow cause the thrombus to propagate away from the heart in case of arteries? If not, then what explains the difference in propagation direction between arteries and veins?