The Silk Vista Baby - The UK experience

Abstract

Background: The Silk Vista Baby (SVB) flow diverter (FDS) is the only FDS deliverable via a 0.017 inch microcatheter and is specifically designed for the distal vasculature. We sought to evaluate the safety and efficacy of the SVB.

Materials and methods: We performed a retrospective review to identify SVB cases at 4 tertiary neurosurgical centres within the U.K. Clinical, procedural, angiographic and follow-up data were collected.

Results: We identified 60 patients (35 female, 58%) of average age 54 ± 10.5 (range 30-72) with 61 aneurysms, 50 (81.9%) located in the anterior circulation. The majority of the aneurysms treated were unruptured (46, 75.4%) and saccular (46, 75.4%). Dome size was 6.2 ± 6.2 mm (range 1-36mm) and parent vessel diameter was 2.3 ± 0.4 mm (range 1.2-3.3 mm).An average number of 1.07 devices were implanted. Coils or other devices were implanted in 14 aneurysms (23.3%). At last angiographic follow-up (n = 55), 7.5 ± 4.2 months post-procedure, 32 aneurysms (57.1%) were graded as RRC I, 7 (12.5%) RRC II, and 17 RRC III (30.4%).Clinical complications, excluding death, were seen in 4 patients (6.8%) including 1 delayed aneurysm rupture and 3 symptomatic ischaemic events. Only one patient had permanent morbidity (mRS 1). 3 patients died during follow-up (5.1%); 2 deaths were related to the aneurysms (3.4%) - one ruptured dissecting MCA aneurysm, and one giant partially thrombosed posterior circulation aneurysm. 93% of patients were mRS ≤ 2 at last follow-up.

Conclusion: The SVB has high rates of technical success and an acceptable safety profile. Distal aneurysms may occlude slower due to relative oversizing of the devices.

Keywords: SVB; aneurysm; flow diversion.

Figure 1.

A patient who presented with acute onset headache, but no evidence of SAH and CTA demonstrated a left ICA aneurysm. Catheter angiography confirmed a wide-necked aneurysm arising from the communicating segment of the ICA (a), which was treated with a single SVB (b) with care taken not to cover the dominant lenticulostriate arriving from the proximal M1 segment. Catheter angiography performed at 6 months post-op demonstrated complete occlusion of the aneurysm with maintained anterograde flow in the covered A1.

Figure 2.

A patient with a giant, partially thrombosed aneurysm of the right PCA initially presented with SAH and was treated with telescoped flow diverters. The patient represented with symptoms of mass effect that demonstrated the aneurysm had increased in size but there was no new haemorrhage (a). Angiography showed a small area of filling through the flow diverter construct (b, white arrow and c). A SVB was therefore, implanted to create a 3 layer construct (d) however, continued filling was still seen (e). The patient failed, on angiographic ground, balloon test occlusion and therefore the procedure was abandoned. 3 months post procedure the patient had a new haemorrhage that ultimately resulted in death.

Figure 3.

A patient presented with a ruptured Acom aneurysm (a) that was initially treated with coiling. Coiling of part of the aneurysm proved difficult resulting in a remnant (b) and on initial MRA there was a stable neck remnant at 1 month (c) that grew on delayed MRA at 14 months (d).

Figure 4.

A significant receurrence of the aneurysm was seen with coil displacement (a). Access to the distal ACAs proved technically very difficult and eventually a SVB was implanted from the left A2 across the Acom and into the right A1 – the so-called chican deployment – with no intra-operative complications. There was no evidence of aneurysmal filling from the left at either the start or the end of the procedure (c). Further coiling was not performed at this time. 11 months post-operatively the patient represented with a new haemorrhage (d) at which point angiography revealed cross-filling of the left ACA from the right without filling of the aneurysm (e) and new filling of the aneurysm from the left that had never previously been seen (f). The aneurysm recurrence was coiled.

Figure 5.

On plain CT a large parenchymal haemorrhage with intraventricular extension was noted (a) with significant improvement in the appearance following decompressive craniectomy and haematoma evacuation (b). Angiography revealed a markedly dysplastic and wide necked MCA bifurcation aneurysm (10.3 mm maximum dome height) with a smaller aneurysm just proximally (c and d). The large aneurysm was treated with coils and a SVB (2.75 x 20 mm) (e) however, after full implantation of the SVB two of the covered branches became acutely occluded (f, white arrows) despite prior anti-platelet medication being given. Anterograde flow was re-established after a further bolus dose of Eptifibatide and prasugrel was given (g) however a follow-up CT scan revealed a large infarction and haemorrhagic transformation.