and Importance: The safety of flow-diverting stents for the treatment of ruptured intracranial aneurysms is unknown.
Presentation: A 35-year-old woman with a ruptured dissecting aneurysm of the intradural right vertebral artery and incorporating the right posterior inferior cerebellar artery was treated with a Pipeline Embolization Device (PED). Five days after reconstruction of the diseased right vertebral segment, she was treated for vasospasm, and retraction of the PED was observed, leaving her dissecting aneurysm unprotected. A second PED was placed with coverage of the aneurysm, but vasospasm complicated optimal positioning of the device.
In addition to the potential risks of dual antiplatelet therapy in these patients, this case illustrates 2 pitfalls of flow-diverting devices in vessels in vasospasm: delayed retraction of the device and difficulty positioning the device for deployment in the setting of vasospasm.
A35-year-old woman with a history of substance abuse was found unconscious and taken to an outside hospital where a non-contrast computed tomography scan demonstrated diffuse subarachnoid hemorrhage (SAH) and early hydrocephalus. She experienced 1 generalized seizure on admission to the outside hospital, but was alert and oriented on transfer to our medical center. A computed tomography angiogram obtained at the outside hospital was concerning for a dissecting aneurysm (ANR) of the intradural segment of the right vertebral artery.
The patient was taken to the angiography suite on postbleed day 1 and a diagnostic angiogram demonstrated a 6-mm fusiform dissecting ANR of the intradural segment of the right vertebral artery incorporating the posterior inferior cerebellar artery (PICA) (Figures 1A, 1B, and 1C). In addition, she had dissection and occlusion of the cervical segment of the dominant left vertebral artery (Figure 1D) and small but patent bilateral posterior communicating arteries. She failed balloon test occlusion of the right vertebral artery immediately proximal to the dissecting ANR. Vascular Neurosurgery was consulted to consider surgical bypass before vertebral sacrifice, but this was considered this too hazardous. As parent vessel occlusion was not a treatment option, reconstruction of the intradural segment of the right vertebral artery was attempted with a single Pipeline Embolization Device (PED) (ev3 Endo-vascular, Inc, Plymouth, Minnesota).
Biplane digital subtraction angiography projection and rotational angiography were performed to measure the artery diameters proximal and distal to the dissecting ANR, and we prescribed our working projections. The artery distal to the ANR was 2.6 mm, and proximal to the ANR, it was 3.8 mm, so we elected to use a 3.75-mm diameter stent. The procedure was performed using a triaxial system: a 6-French guide catheter (Neuropath; Codman & Shurtleff, Inc, Raynham, Massachusetts), 0.058-inch guide catheter (Navien; ev3 Endovascular, Inc), and a 0.027-inch microcatheter (Marksman; ev3 Endovascular, Inc). The micro-catheter was advanced beyond the dissecting ANR without incident (Figure 2A). The patient was given an eptifibatide bolus, and a maintenance infusion was started. After this, a 3.75 × 14-mm PED (ev3 Endovascular, Inc) was deployed across the dissecting ANR and the right PICA origin without incident (Figures 2B, 2C, and 2D).
On postbleed day 6, the patient returned to the cath lab for a diagnostic angiogram because there was clinical concern for vasospasm. The angiogram revealed moderate to severe spasm within the posterior circulation. Intra-arterial nicardipine was infused, and there was a satisfactory angiographic response. However, on the postnicardipine angiographic run (Figures 3A and 3B), it was clear that the PED had foreshortened to its nominal length and the dissecting ANR was now only partially covered by the PED (Figures 3C and 3D).
For this reason, the patient was intubated, and we prepared to telescope a second PED through the existing PED to divert flow from the dissecting ANR. The same triaxial system described earlier was used. The artery distal to the ANR now measured 2.2 mm, and proximal to the ANR, it measured 4.0 mm, so we elected to use a 4.00-mm diameter stent. The microcatheter was placed across the ANR and a 4.0 × 14-mm PED was introduced through the microcatheter with the tip of the capture coil extending into the basilar artery. At this point, an angiogram demonstrated severe spasm in the vertebral artery distal to the ANR with flow cutoff. Because there was flow arrest distal to the recently ruptured dissecting ANR and we were concerned about the increased pressure experienced within the ANR, we initiated deployment of the PED in the hope that it would expand and open the artery rapidly. The device was opened just proximal to the vertebrobasilar junction and immediately restored flow (Figures 4A and 4B). Because the position was thought to be slightly too distal in the vertebral artery, we attempted to pull the stent more proximal, but we were unable to pull the system into a more proximal position using the usual technique of pulling both the microcatheter and stent simultaneously. We then attempted to “cork” the device to pull the stent more proximal. The capture coil was drawn into the stent and secured against the end of the microcatheter to capture the stent. At this point, we retracted the microcatheter and capture coil together, and after some traction, the catheter and capture coil suddenly retracted proximally with unintended unsheathing of the entire PED. The PED successfully telescoped and deployed within the existing PED, and with the ANR still opacified with contrast, flow was diverted from the ANR. The vasospasm was also treated with intra-arterial nicardipine over 60 minutes, and the vessel caliber improved. There were no thromboembolic complications during this second procedure or during the hospitalization. The patient returned to the cath lab on postbleed day 12 to evaluate for vasospasm. Spasm in the right vertebral artery had resolved, and the ANR remained covered by the PED construct. In addition, partial recanalization of the previously dissected left vertebral artery was seen. The patient continued to convalesce and was discharged on postbleed day 20 and has since returned to her neurological baseline.
The PED is a device approved by the US Food and Drug Administration that is used to reconstruct large, wide-necked ANRs in certain segments of the anterior circulation. In this case, the PED was used to treat a ruptured dissecting ANR of the vertebral artery. Ruptured dissecting ANRs of the intracranial segment of the vertebral artery are highly morbid and have a high rate of rebleeding and mortality if left untreated.1,2 Although the use of the PED to treat an acutely ruptured dissecting ANR of a vertebral artery has been reported,3 this case is reported for 2 other reasons. It is the first report that we are aware of that documents device retraction after deployment using the PED. In addition, we encountered difficulty using commonly used techniques for positioning the PED in the face of vasospasm.
Various treatment options for dissecting ANRs of the vertebral artery that incorporate the PICA have been described.3–6 A reconstructive technique was required in this patient with a contralateral, occluded vertebral artery dissection, small posterior communicating arteries, and a failed right vertebral artery balloon test occlusion coupled with acute SAH and a risk of vasospasm. PICA bypass was deferred by the admitting vascular neurosurgeon. Endovascular options included use of a highly porous nitinol stent with or without coiling and a less porous flow diverter stent with or without coiling. We elected to use the flow-diverting stent and chose not to use coils because of the risk of jailing a catheter and coiling into a small ruptured fusiform dissecting ANR. Patients treated with any stent device require dual antiplatelet therapy, and the morbidity of a rebleed may be increased by dual antiplatelet therapy.
De Barros Faria et al7 reported the treatment of 23 dissecting ANRs with the PED. Although SAH was the most common presentation (52%), only 4 patients were treated acutely, and it is unclear from the paper and online table where these 4 acutely treated ANRs were located. Fifty-one devices were used to treat these ANRs, and 46 PEDs (90%) were successfully deployed. One device fell into the ANR sac, 2 devices slipped proximally during deployment, 2 presented with exaggerated shortening while compacting, and additional PEDs were immediately deployed. It is not stated whether these deployment failures occurred in any of the 4 patients presenting with acute hemorrhage, and it appears that at least 2 of the 4 patients who presented with SAH died.
McAuliffe et al8 recently published their experience of 11 patients with acute SAH treated with the PED: 6 in the first 2 weeks (4 within 72 hours) and 5 in the third or fourth week (no ANR was a dissecting vertebral artery ANR). The mortality rate was 18.2% with 2 ruptures (both of these patients were treated in the acute SAH setting). There was no procedure-related symptomatic significant morbidity in the other 9 patients. Eight of the 9 patients who survived had occluded ANRs at 6 months. Based on their experience, they recommended using a flow-diverting stent in SAH only if necessary and, whenever possible, to coil behind the device.
Delayed retraction of the SILK device has been reported in 2 series.9,10 In 1 case,9 the retraction led to a fatal ANR rebleeding, whereas in the other, the retraction was clinically silent, perhaps because the ANR had been previously treated with coils.10 In our case, we believe that the initial PED was deployed within a vessel in possible spasm and the ostensible diameter of the distal segment enlarged somewhat after stent placement, which caused the stent to foreshorten or retract and expose the ANR. Fortunately, our patient returned to the cath lab for vasospasm treatment, and the unprotected ANR and retracted PED were discovered. A second PED device was placed across the ANR for protection and, as before, the device remained elongated due to constraint within the vessel. A follow-up angiogram on postoperative day 12 demonstrated that the ANR remained covered but incompletely thrombosed. In contrast to the approach of Narata et al,3 we did not feel compelled to place yet another PED to promote a more immediate thrombosis of the ANR, understanding that delayed thrombosis of this ANR may pose risk in a patient receiving antiplatelet therapy.
We encountered problems with positioning this device because of the vasospasm gripping the partially deployed stent. The PED has been widely used using a technique of first partially opening the device distally in the vascular anatomy and then retracting the partially opened device along with the catheter to attain ideal positioning. In some circumstances, the device can be maneuvered more proximally by “corking” the device, which involves trapping the partially deployed device between the microcatheter tip and the capture coil. In this case, neither of these maneuvers worked because of the distal vasospasm that gripped the partially deployed device and froze it in the position of initial deployment.
The safety of flow diversion for the treatment of ruptured ANRs is unknown. Just as it may be prudent to coil behind a flow-diverting stent in this setting, we would encourage early angiography after PED placement to monitor for delayed retraction of a device. Furthermore, placement of the PED within a vessel in vasospasm may hinder the ability to precisely position the PED using routine maneuvers and “corking” of the PED.
Endovascular aneurysm therapy continues to evolve with more cuttingedge treatments and even novel approaches to aneurysm repair. Whereas exclusion of the aneurysm from the cerebral circulation has been the thrust of the past several decades, the Pipeline Embolization Device has now begun the generation of aneurysm diversion and repair of the normal vasculature. Given the tremendous enthusiasm for the device, cases that highlight potential complications are essential for the literature and an important resource to all practitioners who may wish to use this stent in their clinical practice.
Many studies have shown the effectiveness of the Pipeline Endovascular Device (PED) in the treatment of unruptured blister, dissecting, dysplastic, saccular, and giant intracranial aneurysms, which are otherwise difficult or impossible to treat with standard endovascular or surgical techniques.2,3,5 However, data regarding the use of this device in acute or subacute SAH is limited to a few case reports and its safety and potential inherent complications have still not been fully understood.3,4
The authors have presented a 35-year-old patient with a diffuse SAH as a result of a ruptured fusiform dissecting aneurysm of the V4 segment of the right vertebral artery, incorporating the PICA. She failed the balloon occlusion test because the contralateral VA was already occluded. Surgical bypass before vertebral sacrifice was considered too hazardous. The posterior communicating arteries were also too small bilaterally. Therefore, preserving that V4 segment was the only option in this particular case. The authors took the perioperative risk of rebleeding and loaded the patient with a bolus dose of Eptifibatide and maintained her on a continuous infusion of this antiplatelet medication. Subsequently, a 3.75 mm × 14 mm flow diverting PED was deployed across the dissected segment of V4 including the right PICA origin without any problem. However, as they expected from that thick SAH, patient's post-operative course was complicated with a clinical vasospasm. This vasospasm was treated using IA Nicardipine. However, the authors encountered with the foreshortening of the previously deployed PED and as a result, the dissecting aneurysm was partially uncovered and filling. In order to fully cover that aneurysm, the authors deployed another 4.0 mm x 14 mm PED telescoping the first stent more distally. They tried to use corking technique; however, because of sever distal vasospasm, it did not work. Although the final obliteration status of this aneurysm is not clear in this paper, however, they successfully diverted flow from this aneurysm in its early post hemorrhage stage and obviously reduced the fluidic pressure on the dissected aneurysm wall.
In this paper, we can see two potential dilemmas and pitfalls of using a flow diverting stent like PED: Delayed retraction (foreshortening) of the device and difficulty of positioning the device for deployment in the setting of vasospasm. These complications, although not common, but have been reported in other studies.1–5
Overall, PED has revolutionized the endovascular treatment of intracranial aneurysms by diverting the flow. As published studies showed, PED can be used with caution in the acute or subacute setting of selected ruptured aneurysms especially where parent vessel preservation is paramount. However, familiarity with the proper deployment of this novel device and special techniques of manipulation such as “corking” and “pseudo-corking” are mandatory for all neurointerventionalists and fellows for safe treatment of patients.1 Delayed angiography is also recommended for detection of unwanted events like foreshortening of the stent.
Pipeline Embolization Device
posterior inferior cerebellar artery
- vascular constriction (function)
- vertebral artery
- lateral medullary syndrome
- ruptured aneurysm
- aneurysm, dissecting
- reconstructive surgical procedures
- devices, medical
- implantation procedure
- military deployment
- occipital nerve stimulation
- fluid flow
- dual antiplatelet therapy