Progressive deconstruction: a novel aneurysm treatment using the pipeline embolization device for competitive flow diversion: case report

Indirect Flow Diversion for Off-Centered Bifurcation Aneurysms and Distant Small-Vessel Aneurysms, a Retrospective Proof of Concept Study From Five Neurovascular Centers

Background: Treatment of cerebral aneurysms using hemodynamic implants such as endosaccular flow disruptors and endoluminal flow diverters has gained significant momentum during recent years. The intended target zone of those devices is the immediate interface between aneurysm and parent vessel. The therapeutic success is based on the reduction of aneurysmal perfusion and the subsequent formation of a neointima along the surface of the implant. However, a subset of aneurysms-off-centered bifurcation aneurysms involving the origin of efferent branches and aneurysms arising from peripheral segments of small cerebral vessels-oftentimes cannot be treated via coiling or implanting a hemodynamic implant at the neck level for technical reasons. In those cases, indirect flow diversion-a flow diverter deployed in the main artery proximal to the parent vessel of the aneurysm-can be a viable treatment strategy, but clinical evidence is lacking in this regard. Materials and Methods: Five neurovascular centers contributed to this retrospective analysis of patients who were treated with indirect flow diversion. Clinical data, aneurysm characteristics, anti-platelet medication, and follow-up results, including procedural and post-procedural complications, were recorded. Results: Seventeen patients (mean age: 60.5 years, range: 35-77 years) with 17 target aneurysms (vertebrobasilar: n = 9) were treated with indirect flow diversion. The average distance between the flow-diverting stent and the aneurysm was 1.65 mm (range: 0.4-2.4 mm). In 15/17 patients (88.2%), perfusion of the aneurysm was reduced immediately after implantation. Follow-ups were available for 12 cases. Delayed opacification (OKM A3: 11.8%), reduction in size (OKM B1-3: 29.4%) and occlusion (D1: 47.1%) were observable at the latest investigation. Clinically relevant procedural complications and adverse events in the early phase and in the late subacute phase were not observed in any case. Conclusion: Our preliminary data suggest that indirect flow diversion is a safe, feasible, and effective approach to off-centered bifurcation aneurysms and distant small-vessel aneurysms. However, validation with larger studies, including long-term outcomes and optimized imaging, is warranted.

Tourniquet parent artery occlusion after flow diversion

BACKGROUND

The Pipeline Embolization Device (PED) is increasingly used for both on- and off-label purposes for treatment of intracranial aneurysms. The device gradually slows flow of blood into the aneurysm, but the high metal coverage of PED promotes endothelialization of the device. Occasionally, this leads to in-stent stenosis that is clinically well tolerated. We present a multi-institutional Pipeline series that includes three cases of gradual asymptomatic occlusion within the PED and parent vessel.

METHODS

Institutional databases at each participating center were searched for patients treated with the PED. Patients with at least 50% stenosis or occlusion were selected and all relevant clinical and radiographic data were reviewed.

RESULTS

A total of 326 cases performed by five neurointerventionalists across four institutions were reviewed. Among these there were three cases of complete occlusion and two cases of stenosis of more than 50%, for an occlusion rate of 0.9%. All patients were clinically asymptomatic.

CONCLUSIONS

A gradual tourniquet-like occlusion can occur following placement of the PED, leading to vessel occlusion. This has been clinically well tolerated by patients in our series due to the formation of pial collaterals as the stenosis progresses, likely due to ischemic preconditioning. Small parent vessel, pre-existing stenosis, fusiform pathology, overlapping devices, and suboptimal antiplatelet therapy seem to be predisposing factors. Further experience and follow-up will allow us to characterize the risk factors and optimize post-procedural therapy for these patients.

Progressive Deconstruction of a Distal Posterior Cerebral Artery Aneurysm Using Competitive Flow Diversion

Progressive deconstruction is an endovascular technique for aneurysm treatment that utilizes flow diverting stents to promote progressive thrombosis by diverting blood flow away from the aneurysm's parent vessel. While the aneurysm thromboses, collateral blood vessels develop over time to avoid infarction that can often accompany acute parent vessel occlusion. We report a 37-year-old woman with a left distal posterior cerebral artery aneurysm that was successfully treated with this strategy. The concept and rationale of progressive deconstruction are discussed in detail.

Concurrent use of the Pipeline Embolization Device and coils for intracranial aneurysms: technique, safety, and efficacy

OBJECT

The use of the Pipeline Embolization Device (PED) as a sole endovascular modality has been described for the treatment of brain aneurysms. The benefit of using coils concurrently with a limited number of PEDs is not well documented. The authors describe their experience with this technique as well as their midterm clinical and angiographic results.

METHODS

This is a retrospective review of patients treated between 2011 and 2014. The authors placed a minimal number of PEDs with the addition of coils using a "jailed" microcatheter technique. A partially dense coil mass was obtained. Immediate and midterm clinical and angiographic results are reviewed.

RESULTS

The authors treated 27 patients harboring 28 aneurysms using this technique. The mean aneurysm size was 11.9 mm, and the mean neck size was 5.4 mm. A mean of 1.48 PEDs were placed per patient, and a mean of 1.33 PEDs per aneurysm were placed. The Raymond score immediately after PED placement was 2 or 3 in 82.1% of the patients. There were no intraprocedural or postprocedural complications. All PEDs were successfully deployed. No clinical or technical adverse effects related to the coil mass were observed. There were no clinical or radiographic signs of ischemia in this group. At follow-up imaging, complete aneurysm occlusion was demonstrated on the first MR angiogram (3-5 months) in all patients who reached this milestone. Follow-up digital subtraction angiography (5-13 months) confirmed complete occlusion in all patients who reached this milestone. All patients maintained their baseline clinical status.

CONCLUSIONS

The deployment of PEDs with concurrent partially dense coiling is safe and efficacious. This technique achieved early complete occlusion and endovascular reconstruction of the parent vessel, without inducing mass effect. Favorable midterm clinical results were observed in all patients.

Modifying flow in the ICA bifurcation: Pipeline deployment from the supraclinoid ICA extending into the M1 segment-clinical and anatomic results

BACKGROUND AND PURPOSE

Utility of the Pipeline Embolization Device extending to the M1 and its clinical and flow consequences at the ICA bifurcation have not been characterized. We analyzed flow modification in cases where a single Pipeline Embolization Device was deployed from the M1 to the distal supraclinoid ICA, covering the A1, for aneurysm treatment.

MATERIALS AND METHODS

A1 flow modifications and size regression in postprocedure and follow-up angiography were analyzed. Vessel diameters and ratios of the proximal A1 and M1 segments and the distal ICA were assessed. Relationships between Pipeline Embolization Device nominal diameter and the vessel diameters at landing zones were obtained. Clinical assessments after flow modification were documented.

RESULTS

Six of 7 patients demonstrated no change of flow in the anterior cerebral artery/anterior communicating artery complex at immediate postembolization angiography. All patients who underwent follow-up angiography demonstrated size regression of the ipsilateral A1. Midterm follow-up angiography revealed complete reversal of flow in the ipsilateral A1 in 4 of 5 patients. One patient did not demonstrate flow modification. This patient had a dominant ipsilateral A1. Vessel ratios in this case demonstrated a unique configuration in favor of maintaining patency of the ipsilateral A1. There were no clinical or radiographic signs of ischemia. One patient experienced asymptomatic angiographic in-stent stenosis at the M1.

CONCLUSIONS

We found that deployment of a Pipeline Embolization Device from the distal supraclinoid ICA to the M1 may result in reversal of flow in the anterior cerebral artery/anterior communicating artery complex and regression of the ipsilateral A1. Preoperative anatomic quantitation and sizing of the Pipeline Embolization Device may predict flow modification results.

Microsurgical strategies following failed endovascular treatment with the pipeline embolization device: case of a giant posterior cerebral artery aneurysm

Treatment of giant posterior circulation aneurysms, via endovascular or microsurgical approaches, carries a high risk of morbidity and mortality. While flow-diverting stents (FDSs) represent a potent therapy for endovascular reconstruction of complex aneurysms, they are also associated with novel complications for which effective salvage techniques are lacking. We present a unique complication from failed treatment with a FDS. A 51 year-old male presented with increasing headaches secondary to a giant, fusiform aneurysm of the left posterior cerebral artery, which was largely thrombosed. Due to progressive enlargement of the aneurysm corresponding to worsening clinical symptoms, the lesion was treated with two Pipeline embolization devices (ev3, Plymouth, MN, United States). Three months after Pipeline embolization device treatment, complete posterior cerebral artery occlusion was observed at the origin of the proximal stent. Despite the lack of arterial inflow, the aneurysm dome continued to grow, resulting in obstructive hydrocephalus. Therefore microsurgical intervention was undertaken to trap and excise the aneurysm. The patient's postoperative course was complicated by multiple venous infarcts, ultimately resulting in death. Successful microsurgical obliteration of aneurysms previously treated with FDSs is extremely difficult. A combination of judicious preoperative planning and meticulous intraoperative surgical technique are requisite for effective management of these complicated cases.

Flow-diversion panacea or poison?

Endovascular therapy is now the treatment of choice for intracranial aneurysms (IAs) for its efficacy and safety profile. The use of flow diversion (FD) has recently expanded to cover many types of IAs in various locations. Some institutions even attempt FD as first line treatment for unruptured IAs. The most widely used devices are the pipeline embolization device (PED), the SILK flow diverter (SFD), the flow redirection endoluminal device (FRED), and Surpass. Many questions were raised regarding the long-term complications, the optimal regimen of dual antiplatelet therapy, and the durability of treatment effect. We reviewed the literature to address these questions as well as other concerns on FD when treating IAs.