Purpose Different hemodynamic models have been studied for the need to estimate the rupture risk of cerebral aneurysms with variable success. We postulated that the transfer of energy by the interaction of the hemodynamic forces with the aneurysmal wall can be related to the risk of rupture. For that reason we introduced a new hemodynamic parameter called energy loss (EL).

Methods 40 side wall, medium sized aneurysms were selected from our aneurysm database from 2003 to 2009. Four incidentally found internal carotid posterior communicating artery aneurysms ruptured during their period of conservative observation (ruptured-IA). 36 stable unruptured aneurysms (stable-IA) with the same location and similar size were examined with EL.

EL is created by separation and turbulence of the flow. We subtracted without aneurysm energy from with aneurysm energy in our model. To avoid the influence from size of aneurysms, the EL was divided by the aneurismal volume.

Results The flow inside the ruptured IAs appeared more complex, and it crashed strongly into aneurysm surfaces. In contrast, the flow inside of stable-IAs passed smoothly through the aneurysms.

The EL in ruptured-IAs was about five times higher than that of stable-IAs.

Conclusion The research indicated that there is a more complex flow pattern with significant turbulence inside of ruptured-IA. The EL created by aneurysms was clearly different between ruptured-IA and stable-IA. The results indicate that the EL may be an important parameter to estimate the risk of aneurysm rupture and that potentially can be developed into clinical application.

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Abstract O-018 Figure 1

Flow visualization at systolic peak. The blood flow in a case before rupture had a more complex flow pattern.