Abstract
BACKGROUND AND PURPOSE: Flow-diverting approaches to intracranial aneurysm treatment had many promising early results, but recent apparently successful treatments have been complicated by later aneurysm hemorrhage. We analyzed 7 cases of aneurysms treated with flow diversion to explore the possible rupture mechanisms.
MATERIALS AND METHODS: CFD analysis of pre- and posttreatment conditions was performed on 3 giant aneurysms that ruptured after treatment and 4 successfully treated aneurysms. Pre- and posttreatment hemodynamics were compared including WSS, relative blood flows, vascular resistances, and pressures, to identify the effects of flow-diverter placements.
RESULTS: Expected reductions in aneurysm velocity and WSS were obtained, indicating effective flow diversion from the sac into the parent artery, consistent with periprocedural observations. In each case with postaneurysm rupture, the result of flow diversion led to an increase in pressure within the aneurysm. This pressure increase is related to larger effective resistance in the parent artery from placement of the devices and, in 2 cases, the reduction of a preaneurysm stenosis.
CONCLUSIONS: Flow-diversion devices can cause intra-aneurysmal pressure increases, which can potentially lead to rupture, especially for giant aneurysms. This relates both to changes in the parent artery configuration, such as reduction of a proximal stenosis, and to the flow diversion into higher resistance parent artery pathways combined with cerebral autoregulation, leading to higher pressure gradients. These may be important effects that should be considered when planning interventions. Potentially dangerous cases could be identified with angiography and/or patient-specific CFD models.
Abbreviations
- CFD
- computational fluid dynamics
- ΔP
- pressure drop
- 3DRA
- 3D rotational angiography
- ICA
- internal carotid artery,
- PA
- parent artery
- PED
- Pipeline Embolization Device
- PTA
- percutaneous transarterial angioplasty
- Post
- after
- Pre
- before
- Pi
- pressure at the model inlet
- Po
- pressure at the model outlet
- Ps
- systemic pressure
- Q
- flow rate
- Ra
- combined resistance of the aneurysm and the parent artery segment at the aneurysm location
- Rd
- distal resistance
- Rp
- proximal resistance
- WSS
- wall shear stress
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