Shape of the aerial pulse is influenced by:
Viscosity of blood
Velocity of blood
Aerial wall expansion
Cross sectional area of aery.
C i.e. Aerial wall expansionThe blood forced into the aoa during systole not only moves the blood in the vessels forward but also sets up a pressure wave that travel along the aeries. The pressure wave expends the aerial wallQ as it travels, and expansion is palpable as the pulse.