  Density waves in the central kpc of galaxies, taking the form of spirals,
bars and/or lopsided density distributions are potential actors of the
redistribution of angular momentum. They thus play an important role in the
overall evolution of the central structures, not mentioning the possible link
with the active/non-active nucleus. I present here kinematical evidences for
the presence of such structures using new sets of observations: two-dimensional
(OASIS/CFHT) and long-slit (ISAAC/VLT) spectrography of nuclear bars and
spirals. I also discuss the importance of $m=1$ modes in the nuclear regions of
galaxies, illustrating this with newly revealed cases and original N body
simulations.
