In order to address the significant clinical need to reduce vein bypass graft failure, researchers have begun to focus on the delivery of prophylactic therapies after vein graft harvest but prior to graft transplant. Homogeneous delivery of these therapeutics throughout the target tissue is limited by the inherent diffusional barriers presented by the luminal and adventitial surfaces of the graft vessel.
To address this limitation, we are developing a pressurization device to improve therapeutic delivery into the vessel wall without causing significant vessel distension. A pressure gradient will be induced from the lumen to the adventitial surface of the vessel, to drive therapy permeation into the target tissue–the intima and media of the graft vein.
Static pressure has been utilized to deliver therapeutic drugs to grafts with promising results. However, our dynamic pressure system will allow for faster, more efficient permeation of the target tissue.
The current method of drug delivery into veins is achieved through passive diffusion. The vein is placed into a drug solution bath for a set time before being implanted into the body. The problem with this method is that full diffusion through the vein takes a long time so efficacious doses are only delivered at the outside and inside wall of the vein. Our pressurization device is different from a passive approach because it actively facilitates drug transport into the vein to increase the speed of drug profusion for effective delivery throughout the entire vein.
We are in the process of prototyping and testing our device. Several tests will be performed on tissue samples to determine the safety and efficacy of this device. This device will also need to go through a premarket approval process with the FDA since is there is no other devices similar to it in the market currently.
At this time, our prototype utilizes dialysis tubing which will encircle the vein graft and provide support and prevent distension of the vessel during pressurization. The vein will be sutured to the dialysis tubing at one end, and a cannula will be inserted into the other end. The cannula, vein, and tubing will then be sutured together. The cannula will be attached to a pressure meter as well as a syringe pump using a three-way stopcock. The pressure meter will monitor the pressure within the lumen of the vessel, and the syringe pump will be utilized to induce said pressure up to 600 mmHg.
FDA Category
This technology will be classified as a class 2 medical device under the terms decided by the FDA. While our device interfaces directly with vein tissue, it does not pose a serious threat to life. If, for any reason, the device causes failure of the vein graft, this condition is not life-threatening. The patient will simply be subject to another surgery to replace the failed graft. For comparison, a heart-lung machine is also classified as a class 2 medical device.