Proposed solution for dorsal internal carotid artery aneurysms: Suggestion of a novel new clip design
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.232282
Source of Support: None, Conflict of Interest: None
Keywords: Difficult clipping, dorsal ICA aneurysms, fragile, normal ICA wall, new clip design
Intracranial aneurysms commonly arising from arterial branching points are berry aneurysms and have a defined neck, which makes the work of clipping a little less complicated. However, there is a distinct subset of patients in whom the aneurysm directly arises from the dorsal wall of internal carotid artery (ICA). In addition to arising from the nonbranching point, these aneurysms are blister-like with thin fragile walls, have a broad-based neck which is not clearly defined, and these aneurysms are not unusually adherent to the surrounding brain parenchyma., They frequently rupture during surgery., Various treatment options available include a direct clipping (by including a small part of normal vessel in the clip jaws); or, its wrapping, clipping and wrapping, and/or institution of an arterial bypass with aneurysm trapping. One of the commonly taught nuances of surgical clipping is to take a part of the normal ICA wall (in addition to the dorsally placed aneurysm) in the clip blades.,, The situation is not very conducive even for the available endovascular options including coiling, stenting with coiling, flow diverters etc., Despite the availability of these plethora of methods, there is a higher-than-usual morbidity and mortality associated with this subset of patients harbouring a dorsal wall aneurysm. None of the available methods provides a perfect solution for this condition, and hence, the quest to find the so-called panacea continues.
The clip design
During clipping of a dorsal ICA aneurysm, there is a risk of laceration of aneurysmal wall or clip slippage due to the pulsations of ICA.
We propose a possible solution to this problem in the form of a new novel clip design. In this design, we propose a fenestrated clip in which the occluding blades (clip jaws) are at the near end of fenestration, i.e., these are placed just at the starting of the fenestration and at right angle to the clip. We prepared a three-dimensional model of the design using Solid works software (Dassault Systèmes SolidWorks Corporation Waltham, MA) [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d, Video 1.
This clip design will act in the following manner: The blades of the clip occlude the dorsally placed aneurysm taking a part of the normal ICA wall, as has been suggested earlier. Simultaneously, the fenestration hugs the ICA. [Figure 2]a and [Figure 2]b. This hugging action of fenestration will prevent clip slippage. We propose a variable fenestration diameter with the length of the clip blades also being of various sizes. In addition, the shape of clip blades can be varied, e.g., having curved clip blades or having clip blades on both sides of the clip hub.
The literature review singularly points to the fact that these dorsal ICA aneurysms are difficult to clip owing to their morphology.,,,, Pathologically, these aneurysms are composed of only a layer of adventitia and blood clot and are devoid of internal elastic lamina and media, which leads to an abnormally high fragility.,,,,,,
The fragility of the wall and an unfavorable relative size of the aneurysm and ICA further complicates the matter in that it leads to a higher chance of postoperative bleeding, presumably because of tearing of the aneurysm or the clip slippage.,,,
Several authors have tried to classify these aneurysms depending upon their angiographic appearance and intraoperative microsurgical anatomy., The take-home message in these classification systems is that during surgery, a portion of the healthy wall of ICA should be taken in the clip blades. Herein, lies a problem. Intraoperatively, the surgeon has to take a decision on how much of the ICA wall should be taken in the clip blades? The surgeon can err on either side. He may incorporate too much of the vessel wall in order to ensure that there is no chance of aneurysmal laceration or avulsion from the ICA, while closing the clip blades. However, in this scenario, while the aneurysm has been secured, the flip side is that it can lead to ICA stenosis/ compromise, with the possibility of an ischemic stroke. On the other hand, taking too little of the vessel wall in the proximity of the aneurysm has the potential risk of causing aneurysmal rupture or laceration as well as clip slippage in the postoperative period.
Another important point is that sometimes there is a tendency of the applied clip to slip off, especially in large circumferential aneurysms. To mitigate this problem, various authors have suggested the use of an encircling material around the aneurysmal neck to secure the primary clip., Shigeta et al., suggested wrapping the ICA with cellulose or using Weck's clips after the primary clipping of the aneurysm. This requires either the use of two different clips or the use of cellulose, which may not be efficacious.
Hence, a mechanism is needed to hold the clip in place. The present proposal of this new clip design is intended to take care of this problem. The surgeon can confidently take only the bare minimum required of the healthy wall of the ICA trunk in the proximity of the aneurysmal neck in the clip. The ICA wall hugging action of the clip fenestration ensures that the clip will not slip.. The advantage of the proposed innovation over the previous clipping techniques is that the work done by two clips earlier can be performed by a single clip.
We clearly reiterate that the mechanical forces as well as the closing force of the proposed clip have not been tested in our clip design. However, what we are proposing is a new clip design, which can be potentially developed to mitigate the problems associated with the clipping of a blister dorsal wall ICA aneurysm that is often prone to an intraoperative rupture during its surgical clipping.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2]