A heart that is slightly enlarged may function okay but a severely enlarged heart has a hard time pumping a sufficient amount of blood.
(A heart; is slightly enlarged; ) (a severely enlarged heart; has; a hard time pumping a sufficient amount of blood) (a hard time; pumping; a sufficient amount of blood)
A heart a severely enlarged heart a hard time
is slightly enlarged has pumping
a hard time pumping a sufficient amount of blood
a sufficient amount of blood