Balloon catheters of various forms are commonly employed in a number of surgical procedures. These devices comprise a thin catheter tube that can be guided through a body conduit of a patient such as a blood vessel and a distensible balloon located at the distal end of the catheter tube. Actuation of the balloon is accomplished through use of a fluid filled syringe or similar device that can inflate the balloon by filling it with fluid (e.g., water or saline solution or contrast solution) to a desired degree of expansion and then deflate the balloon by withdrawing the fluid back into the syringe.
In use, a physician will guide the balloon catheter into a desired position and then expand the balloon to accomplish the desired result (e.g., clear a blockage, or install or actuate some other device). Once the procedure is accomplished, the balloon is then deflated and withdrawn from the blood vessel.
The balloon is commonly used to deploy a stent in order to permanently open a blockage, which remains in place after the catheter is withdrawn. The stent may be coated with a substance that prevent tissue stenosis/restenosis or promotes healing of the injury caused by opening the vessel.
While the use of a stent is established for blocked vessels, it is not always the most appropriate treatment. Stent deployment is known to cause damage to the vessel wall which in itself can be the cause of further vessel closure. When the stent is of the drug eluting variety, it is not possible to stop treatment without stent removal, entailing additional surgical procedures. Delivering a precise and/or intermittent treatment is also precluded by a drug-eluting stent, thus treatment optimization is not possible. Moreover, a stent is not suitable as a vehicle of high-dose treatment regimens. In addition, it is not suitable for treating large cavities, or cavities having a non-cylindrical profile.
Coated balloons are useful for addressing the above, and are known in the art for the delivery of active pharmaceutical substances. US 2010/0076539, US 2009/0054837, WO 2009/111712, DE 20 2009 006 632, and US 2006/0020243 describe coated balloons in which the active pharmaceutical substance is held between the balloon folds. A problem in the art is systemic toxicity which arises from partial unfolding of the wings during advancement of the catheter through the vasculature, the bends of which can loosen the wings of conventionally folded balloons.
The present invention aims to overcome the problem of periodic delivery of medicaments to cylindrical or non-cylindrical bodily cavities and to provide a means to deliver doses that avoids systemic toxicity.