Analysis of flow changes in side branches jailed by flow diverters in rabbit models.

Understanding the flow alteration in side branches during flow diversion treatment of cerebral aneurysms is important to prevent ischemic complications and improve device designs. Flow diverters were placed in the aorta of four rabbits crossing the origin of side arteries. Subject-specific computational models were constructed from 3D angiographies and Doppler ultrasounds (DUSs). Flow simulations were run before and after virtually deploying the flow diverters, assuming distal resistances remained unchanged after treatment. All jailed arteries remained patent angiographically 8 weeks after treatment. The computational models estimated decreases compared to pretreatment in the mean flow rates between 2% and 20% and in peak flow rates between 5% and 36%. The major changes were observed during systole. Flow patterns did not exhibit recirculation zones before treatment. Implantation of the flow diverters altered the flow structure only locally near the device wires. No major recirculation regions were created or destroyed. Flow diverters seem safe with respect to perforator or side branch occlusion. Relatively small changes in flow rates through jailed arteries are expected, even for moderate to large degrees of coverage of their origins. These results seem consistent with previous clinical experiences where no or very few complications related to perforator occlusion have been reported.