An implantable medical device is disclosed having a helical construct including a set of spiral coils for local in vivo application of a therapeutic substance in a biological lumen. The helical construct is configured to apply less than 0.75 Bar of pressure to the biological lumen wall. The helical construct can have at least two sets of spiral coils having opposing helical directions. The device can be used for the treatment of vascular disorders such as restenosis and vulnerable plaque.