We report our initial experience with a coaxial dual-lumen Ascent balloon catheter system for the remodeling technique in wide-neck aneurysm treatment. This is the largest series describing the use of this device for wide-neck aneurysm treatment. This report contributes to the growing body of literature describing novel techniques and new devices that expand the possibilities of endovascular treatment of complex aneurysms.
The purpose of temporary parent artery occlusion in aneurysm coil embolization is to prevent coil prolapse, improve coil positioning, and allow for greater density packing. A recent meta-analysis suggested that balloon-assisted coil embolization leads to greater initial occlusion rates and more durable occlusion when compared to unassisted coil embolization (Shapiro et al., 2008
). Additionally, the balloon occlusion technique avoids permanent device implantation as compared to stent-assisted embolization techniques, which is of considerable benefit in treatment of ruptured aneurysms when antithrombotic therapy poses risk of hemorrhagic complication. Complete aneurysm occlusion was achieved in all aneurysms in this series.
Aneurysm size was large in our series, ranging from 6 to 15
mm. The average neck size was also large, ranging from 5.0 to 7.8
mm. These characteristics are important for balloon performance as larger neck size may pose greater challenge in initial balloon positioning and maintaining placement during repeated inflations.
Aneurysm locations varied, providing a reasonably well-distributed sample. The patient population was relatively young (average age 54
years) and vessel tortuosity was moderate. As with any device, navigation of tortuous vessels will hinder performance and this was possibly the cause of inability to safely position the Ascent balloon in cases 3 and 4. Improved distal support through use of a distal access catheter may reduce this limitation.
A unique characteristic of the Ascent balloon system is the dual-lumen design that allows delivery of the balloon catheter over a variety of microwires, allowing for flexibility in the choice of wires. Performance with use of different wires is not known and further experience may identify specific wires that provide an optimal pairing. This design may be of potential usefulness in the event of artery rupture. In the present series, this new device allowed use of an exchange-length wire, which is not feasible with other compliant aneurysm balloon catheters. Moreover, the over-the-wire devices do not allow for saline perfusion around the microwire or removing the wire to switch to a different microwire while leaving the balloon catheter in the body. Occlusion of the balloon holes with blood clots is another potential drawback of the over-the-wire balloons preventing full deflation on occasion.
The dual-lumen design allows for delivery of the Ascent balloon over an exchange wire, which can be useful in the balloon-in-stent remodeling technique (Figure ). Following delivery of a stent, the exchange wire can remain in position, securing distal access, and allow for advancement of the dual-lumen balloon to the aneurysm neck. This eliminates the need to re-cross the stent.
Figure 3 A wide-neck blowout morphology right MCA aneurysm (A) was treated using a balloon-in-stent technique. An Enterprise stent was implanted across the aneurysm neck [(B), black arrows] and an Ascent balloon was intermittently inflated across the neck (white (more ...)
The ability of a device to track well within the cerebrovasculature, or the “trackability,” is an important characteristic of any neurointerventional device. This concept involves factors that affect the ability of a device to travel the course of a vessel, which include the inherent characteristics of a device, such as the flexibility and responsiveness to proximal manipulation, as well as the behavior of the device as a result of interaction with the surrounding vessel, such as the ability to glide. The Ascent balloon was not successfully used in two of our cases due to the inability to advance the balloon to the target lesion, which may have been from the device trackability in a tortuous cerebrovascular anatomy. The trackability may be related to interaction of the device over an exchange wire, a characteristic that may be important in wire selection. The trackability may also be affected by stiffness, a characteristic that may be theoretically increased due to the dual-lumen design.
Repeated balloon inflation may lead to unintended movement of the adjacent microcatheter resulting in loss of aneurysm lumen access, balloon migration, and parent artery rupture. Five cases required delivery of 10 or more coils, suggesting balloon positioning and access is well maintained throughout the technique of intermittent balloon inflation.
Complications from balloon remodeling primarily include thromboembolism, which range from about 2 to 8%, and parent artery perforation, which is under 2% in large series (Shapiro et al., 2008
; Cekirge et al., 2011
). A transient clot formation was noted in case 1 distal to the site of balloon placement in the parent artery. This thrombus resolved during abciximab administration and the patient experienced no clinical sequelae. The simultaneous use of two microcatheters and resulting compromised perfusion in small arteries may theoretically contribute to thrombotic risk in this technique, however there has been no evidence of an increased risk of thromboembolic complications in the balloon-assisted technique compared to unassisted coil embolization (Shapiro et al., 2008
). Follow-up outcome measures include occlusion durability, which is about 72% in large series (Moret et al., 1997
; Shapiro et al., 2008
Limitations of this report include the retrospective design and small sample size. Additionally, selection bias exists among operators and the decision to use one of three non-detachable compliant balloons available at our institution.