  Recent experiments on heterostructures composed of two or more films of
cuprate superconductors of different oxygen doping levels\cite{Yuli,Gozar} have
shown a remarkable T$_c$ enhancement (up to 50%) relative to single compound
films. We provide here a simple explanation of the enhancement which arises
naturally from a collection of experimental works. We show that the enhancement
could be caused by a structural change in the lattice, namely an increase in
the distance of the apical oxygen from the copper-oxygen plane. This increase
modifies the effective off-site interaction in the plane which in turn enhances
the d-wave superconductivity order parameter. To illustrate this point we study
the extended Hubbard model using the fluctuation exchange approximation.
