A ventricular assist device includes an intravascular blood pump and a collapsible frame. The vapor chamber includes a heated section attached onto the base, two heat transmitting sections bent and extended upward from both sides of the heated section respectively, a condensing section bent and extended laterally from each of the two heat transmitting sections, two heat dissipating elements having a heated base, and heat dissipating fins disposed on the heated base. The washer or the plastic lens has a recess in a contact side with each other except an outer edge thereof, so that the washer and the plastic lens contact each other along their outer edges.