With no explanation, label each line with "O", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting", "art-writtenart", "building-airport", "building-hospital" or "building-hotel" preceded by ":".
The
cause
is
an
accessory
pathway
in
the
heart
which
conducts
from
the
ventricles
back
to
the
atria
.
The:O
cause:O
is:O
an:O
accessory:O
pathway:O
in:O
the:O
heart:O
which:O
conducts:O
from:O
the:O
ventricles:O
back:O
to:O
the:O
atria:O
.:O