Local drug delivery catheters: functional comparison of porous and microporous designs

BACKGROUNDThe porous (Wolinski) balloon was designed to allow local delivery of compounds targeted to inhibit postintervention restenosis; however, successful use of the device has been hampered by arterial trauma caused by the balloon itself. This study utilized several experimental systems to assess the functional characteristics of the porous balloon catheter. This information was utilized to design and test a new microporous infusion catheter for local intra-arterial drug delivery. METHODSFlow characteristics in fluid and semisolid media as well as arterial trauma by light and electron microscopy were documented for the porous and microporous balloons. In addition, the efficacy of methylene blue delivery in situ and in vitro was documented and quantified for the microporous design. RESULTSThe porous balloon exhibits flow characteristics consistent with orifice-related streaming that produces arterial trauma. By maximizing external balloon-pore density and minimizing pore size, the microporous design minimizes streaming in test systems. This is manifested by minimal arterial trauma when applied to intact arteries. The microporous catheter is effective for dye delivery both in situ and in vivo. CONCLUSIONSThe microporous catheter design offers improved functional characteristics when compared with the porous balloon for local intra-arterial drug delivery.