The project “Heart-e-Gel” was funded by the European Commission under the FP7 Specific Programme “Cooperation” and it commenced on the 1st September 2010 for the duration of 3 years. The main objective of the project is to develop biomedical microsystem solutions, based on Electro-Active Hydrogels (EAH), for the treatment of cardiovascular conditions requiring occluding, filling or sealing of vessels or cavities.

Minimal invasive procedures are targeted, such as “arterial occlusions” and “abdominal aortic aneurysm leaks”. The concept (see below) is to introduce a small hydrogel implant into a blood vessel and manoeuvre it to the intended treatment location using a catheter type delivery device. At its target destination the gel can then be allowed to swell until it fully occludes the vessel (or fulfils another function).

The figure above shows the concept of stopping a bleeding in an artery/vein (top left). Top right shows a delivery device with an electroactive hydrogel that is being shrunk using an electrical bias until it is at the target location. Part of the project involves the development of effective electrode configurations and electrical pulsing regimes. (bottom left) once at the target location the electrical bias is removed and the gel is allowed to swell in the blood vessel. (bottom right) fully swollen gel that occluded the bleeding.
 
During the project an EAH was developed with low cytotoxicity, made of biocompatible water soluble Pluronic modified with acrylate end groups for electroactiveness. Under electrical bias the swelling behaviour of the EAH can be controlled via dynamic osmotic gradients.

From the clinical perspective a fast swelling rate would be ideal to casue minimal disruption of the patient’s blood circulation and also to reduce the procedure time. In practise faster swelling times can be obtained with ”porous” EAH, but there then will be a mechanical strength trade-off and also the absolute amount of swelling might reduce to some extend. On the other hand a porous EAH surface texture could increase the friction with the vessel wall, which reduces the need for absolute swelling. The study of these trade-offs are presently under investigation using ex vivo animal vessels. 

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