Endovascular coiling is used to treat cerebral aneurysms. The main goal is prevention of rupture in unruptured aneurysms, and prevention of rebleeding in ruptured aneurysms by limiting blood circulation to the aneurysm space. Clinically, packing density is recommended to be 20-30% or more of the aneurysm's volume, typically requiring deployment of multiple wires. Higher volumes may be difficult due to the delicate nature of the aneurysm; intraoperative rupture rates are as high as 7.6% for this procedure. In ruptured aneurysms, coiling is performed quickly after rupture because of the high risk of rebleeding within the first few weeks after initial rupture.
The patients most suitable for endovascular coiling are those with aneurysms with a small neck size (preferably less than mm), luminal diameter less than 25 mm and those that are distinct from the parent vessel. Larger aneurysms are subject to compaction of coils, due to both looser packing densities (more coils are needed) and increased blood flow. Coil compaction renders them unsuitable as they are incapable of stemming blood flow However, technological advances have made coiling of many other aneurysms possible as well.
A coil is first inserted along the aneurysm wall to create a frame, with the core then being filled with more coils. A series of progressively smaller coils may also be used. Success is determined by injecting a contrast dye into parent artery and qualitatively determining if dye is flowing into the aneurysm space during fluoroscopy. If no flow is observed, the procedure is considered completed. In the case of wide-necked aneurysms a stent may be used.
Balloon-assisted Coiling is recommended when the aneurysm sac equals or exceeds 2cms. Both wide-necked and main artery branch aneurysms represent a challenge for conventional endovascular coil embolization due to the risk of coil migration.
In balloon-assisted rapid intermittent sequential coiling technique, predetermined number of coils (usually between three and five coils per balloon inflation cycle) were deployed in the wide-necked aneurysm within a maximum balloon inflation time of five minutes. This allows multiple coils to brace with each other and form stable scaffolding for deployment of further coils. This technique was used when the first framing coil was felt to be unstable after balloon deflation and was prolapsing back into the parent vessel. We describe our experience with a balloon-assisted rapid intermittent sequential coiling technique as an alternative to stent-assisted coiling in patients with ruptured wide-necked aneurysm and in relative contraindications for stent-assisted coiling like unfavorable tortuous vascular anatomy or parent artery too small for stent deployment.
When using traditional balloon remodeling technique, temporary inflation of the balloon across the aneurysm is performed while placing a single coil within the aneurysm sac and subsequently deflating the balloon to ensure no coil loops migrate into the parent vessel before final detachment. If the first framing coil was felt to be unstable and the coil prolapsing back into the parent vessel after balloon deflation, a decision was made to attempt balloon-assisted rapid intermittent sequential coiling. Unlike the traditional approach, in this technique, we place a predetermined number of coils (usually between three and five coils per balloon inflation cycle) during a maximum balloon inflation time of 5 minutes. This allows multiple coils to brace each other within the aneurysm and form stable scaffolding for deployment of further coils. The balloon is then deflated to allow cerebral reperfusion and to evaluate if any coil loops are prolapsing into the parent artery. Balloon inflation is never carried out for longer than five minutes to reduce ischemic time. The procedure is performed under full heparinization (activated thromboplastin time maintained at 250-300). The technique is repeated as necessary to achieve adequate intra-aneurysmal coil packing density.
Endovascular therapy is a well-established treatment modality for cerebral/intracranial aneurysms. Large, complex, wide-necked, and fusiform aneurysms were initially considered unamenable to endovascular coil embolization. With the advent of stents designed specifically for the intracranial circulation, such aneurysms can now be safely and efficiently managed endovascularly.1 Self-expanding stents allow denser aneurysm packing with increased neck coverage and may also improve treatment durability through a combination of flow-diversion, parent vessel straightening, and fibroelastic tissue formation along the neck of the aneurysm.
Stent-assisted coiling of intracranial aneurysms is safe, effective, and provides durable aneurysm closure. Higher complication rates and worse outcomes are associated with treatment of ruptured aneurysms. Stent delivery before coil deployment reduces the risk of procedural complications. Staging the procedure may not improve procedural safety. Closed-cell stents are associated with significantly lower recanalization rates.
The results of stent-assisted coiling (SAC) have varied widely across different studies. In a French series of 216 aneurysms treated with stents, the rates of permanent morbidity and mortality were as high as 7.4% and 4.6%, respectively. Elsewhere, morbidity and mortality rates with SAC were found to be low.4–7 Several questions remain unanswered: Does the type of stent (open versus closed-cell design) affect the rates of complication and recanalization? Should stents or coils be delivered first? Does staging the procedure provide any benefit for procedural complications or patient outcome? Is stenting of acutely ruptured aneurysms associated with higher complication rates and worse outcomes?
We assess the safety and the long-term efficacy of stent-assisted techniques and determine the predictors of complications, initial aneurysm occlusion, recanalization, and immediate outcome in a series of 552 aneurysms treated by us.
The decision to use SAC was based on the aneurysm morphology, aneurysm–parent vessel relationship, and comorbidities that rendered a patient a poor surgical candidate. The use of self-expanding stents was generally indicated for wide-necked aneurysms ( greater than 4 mm) or those with an unfavorable fundus-to-neck ratio (less than 1.5) and as a rescue when coils prolapsed into the parent vessel.
SAC procedures were either staged or performed during a single session at the operator’s discretion. In staged procedures, the stent was placed first across the aneurysm neck and left to endothelialize for 6 to 12 weeks before the patient was brought back for coil embolization.
What is flow diversion? Flow diversion is an endovascular technique whereby instead of placing a device inside the aneurysm sac, such as with coiling, the device is placed in the parent blood vessel to divert blood flow away from the aneurysm itself.
Procedures:
Almost immediately the blood flow to the aneurysm is reduced, and the complete closure of the aneurysm occurs between 6 weeks to 6 months after the procedure.
A flow diversion procedure may be performed to treat an unruptured wide-necked brain aneurysm. Flow diversion is one method of removing the need to enter the aneurysm, which is the most dangerous part of endovascular treatment of aneurysms. The risk of rupturing the aneurysm during surgery is greatly diminished by not placing a device inside the aneurysm.
Flow Diversion may be used to treat large or giant wide-necked brain aneurysms that are poor candidates for other types of procedures. Coiling of the aneurysm is often combined with the placement of a flow diverting stent to encourage thrombosis within the aneurysm. The stent prevents the coils from exiting the aneurysm and maintains the pressure on the coils necessary to keep the aneurysm under control. The stent then acts as scaffolding and “assists” the coils by securing them in place and preventing them from falling out. Over a period of time, natural healing occurs and the blood clots. This diverts blood away from the weakened vessel walls and prevents a rupture. Complete obliteration of the aneurysm may require weeks to months. Flow-diverting stents are now the treatment of choice for large and giant aneurysms involving the most proximal (cavernous) segment of the internal carotid artery.
In general, the use of stents, including flow-diverter stents, is limited to the treatment of unruptured aneurysms because of the need to place the patient on two antiplatelet agents which increases risks of bleeding. Conceptually, flow diverters allow endoluminal reconstruction rather than endovascular filling.The treatment is focused on reconstruction or remodeling of the weak blood vessel harboring the brain aneurysm.
The Contour PVA Embolization particles are small and irregular flakes of polyvinyl alcohol, which are used for permanent occlusion within a blood vessel. The Contour PVA Embolization Particles have been proven to be safe and effective in many clinical scenarios for decades.
Vascular occlusion should only be performed by physicians possessing skilled interventional occlusion experience in the territory intended to be embolized.
A thorough evaluation of a patients medical condition, vascular pathways and the desired embolization goal is necessary to achieve successful occlusion. This evaluation should include baseline angiography to determine the presence of potentially dangerous collateral pathways.
When Contour Embolisation is performed?
Wide-necked bifurcation aneurysms pose a significant challenge to the treating clinician. The Contour Neurovascular System embolization device is a novel tool for the treatment of such intracranial aneurysms.
The Countour neurovascular device is novel intrasaccular technology for treating intracranial aneurysms of varying morphology including WNBA. This device is a dual-layer radiopaque nitinol memory mesh. Due to its unique shape, it acts as both a flow disrupter and a flow diverter and is designed to reconstruct the natural bifurcation of the artery. It can be deployed using current microcatheter technology and specifically targets the neck of the aneurysm.
Detachment is achieved using an electrolytic device. Sizing is based primarily on the aneurysm neck size and maximum diameter
the Contour device in the treatment of WNBAs looks promising and our series represents some of the first patients ever treated with the new device. The sizing of the device is relatively easy, making procedural planning simple, and the device is stable and relatively safe to use. It is also easy to navigate into the aneurysm using current 0.027 microcatheters. Long-term follow-up data will be crucial to assess this novel technology in the treatment of WNBAs as a safe and effective alternative to existing technology.
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