Atherogenesis and atherosclerosis have long been thought to be a major inciting factor responsible for the formation of aneurysms in the cerebral vasculature. We propose that inception of side-wall aneurysms occurs in hemodynamic environments that promote an atheroprotective endothelial phenotype and that the atheroprotective phenotype is therefore aneurysmogenic.
The authors report the case of 14-year-old girl with a history of myelomeningocele and previously shunt-treated hydrocephalus who presented with right-sided abdominal pain and subcutaneous emphysema that developed over a 1-week period. A CT scan of the patient's abdomen revealed a retained distal ventriculoperitoneal (VP) catheter with air tracking from the catheter to the upper chest wall. Given the high suspicion of the catheter being intraluminal, an exploratory laparotomy was performed and revealed multiple jejunal perforations. The patient required a partial small-bowel resection and reanastomosis for complete removal of the retained catheter. Six other similar cases of bowel perforation occurring in patients with abandoned VP and subdural-peritoneal shunts have been reported. The authors analyzed these cases with regard to age of presentation, symptomatic presentation, management, morbidity, and mortality. While there was 0% mortality associated with bowel perforation secondary to a retained distal VP catheter, the morbidity was significantly high and included peritonitis and small bowel resection.
Objective The natural history intracranial aneurysms (IA) remains poorly understood despite significant morbidity and mortality associated with IA rupture. Hemodynamic impingement resulting in elevations in wall shear stress and wall shear stress gradient (WSSG) has been shown to induce aneurysmal remodeling at arterial bifurcations. We investigate the hemodynamic environment specific to side-wall pre-aneurysmal vasculature. We hypothesize that fluid impingement and secondary flow patterns play a role in side-wall aneurysm initiation. Methods Eight side-wall internal carotid artery aneurysms from the Aneurisk repository were identified. Pre-aneurysmal vasculature was algorithmically reconstructed. Blood flow was simulated with computational fluid dynamic simulations. An indicator of isolated fluid impingement energy was developed by insetting the vessel surface and calculating the impinging component of the fluid dynamic pressure. Results Isolated fluid impingement was found to be elevated in the area of aneurysm initiation in 8/8 cases. The underlying fluid flow for each area of initiation was found to harbor secondary flow patterns known as Dean’s vortices, the result of changes in momentum imparted by bends in the internal carotid artery (ICA). Conclusion Isolated fluid impingement and secondary flow patterns may play a major role in the initiation of side-wall aneurysm initiation. We are unable to determine if this role is through direct or indirect mechanisms but hypothesize that elevations in isolated fluid impingement mark areas of cerebral vasculature that are at risk for aneurysm initiation. Thus, this indicator provides vascular locations to focus future study of side-wall aneurysm initiation.
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