aneurysmal clips

1. Aneursym Clips

2. History And Evolution of Aneurysm
Clips
• Modern aneurysm clip is the result of almost a
century of innovation from Cushing’s
malleable silver clips and Mayfield’s
repositionable spring loaded clips to their
current modern avatar. Dandy was the first to
use a clip on an aneurysm. In 1937, he applied
a V-shaped malleable silver clip to the neck of
an internal carotid artery (ICA) aneurysm and
obtained excellent results.

3. • There are four major clip designs that are
currently available in the market, and these
are the McFadden Vari-Angle, Sundt Slim-Line,
and Sugita and Yasargil type clips. Of these,
the last two are commonly available. The
mechanism of clip opening and closure is the
basis for dividing clips into U/V type, pivot,
mobile fulcrum, and alpha types.

4. • The U/V configuration clip, when originally designed by
Cushing, was malleable. Olivecrona added flanges to
the clip so that it can be opened in case of improper
application. An important advancement was the
incorporation of a spring mechanism to allow repeated
opening and reapplication. According to McFadden,
the spring mechanism was developed in 1840 by the
French instrument maker Joseph Charriere. He
described it as one of the most significant alterations in
the basic forceps design. Charriere’s design
modification reversed the action of the forceps—
opening the blades when compressed and letting it
close when released.

5. • The pivot clip resembles a clothes peg with a central pivot and an
external spring mechanism to allow for opening. Examples of these
include the Heifetz and Lougheed-Kerr clips. The next development
in clip design was the development of clips that had no external
springs but were designed to open and close based on the elastic
properties of the metal and the shape of the clip itself. The first of
these was the mobile fulcrum Scoville clip that had an advantage of
not trapping branches or vessel wall at its fulcrum point.
• However, the Scoville clip had a tendency to slip off. The alpha clip
is the most widespread design available today. The widely popular
Yasargil and Sugita clips follow this design. It is simply a crossed
shaft design that resembles the first Greek letter ‘α’.

6. Types Of Aneursym Clips
• Clips are also classified as standard and mini based on
their size. They are available in a variety of shapes and
sizes. In-vogue Sugita and Yasargil clips are available as
standard, mini, and extra-long sizes. They are also in
myriad shapes—straight, curved forward, backward
and sideward, bent forward, backward and sideward,
and bayoneted.
• In addition, clips may also be fenestrated. A
fenestrated clip has a second loop apart from the alpha
to incorporate a branch if required. Kees made a
fenestrated clip overnight when Professor Drake
requested him to create a special clip for an otherwise
unclippable basilar bifurcation aneurysm.

7. • The ipsilateral posterior cerebral artery was preserved within the
fenestration. Select clip types that merit mention are the booster
clips, t-bar clips, and Sundt graft clips. A booster clip is used to
augment a long clip placed across a giant aneurysm neck. Long clips
have low closing force at the tip. A booster clip fits over the long
clip strengthening closure across the neck and preventing its
slippage. T-bar clips help in parent artery reconstruction by having a
horizontal segment that is perpendicular to the direction of the clip
itself. The horizontal segment occludes the neck while the parent
artery is incorporated in a fenestration. Sundt clip incorporates a
Dacron mesh to repair vessel wall accidentally torn during surgery.
These clips, though rarely available now, can be used in blister
aneurysms, or during catastrophic aneurysmal neck tears.

8. Material Science in Aneurysm Clips
• The earliest aneurysm clips were made from materials
traditionally considered biologically inert such as silver.
Over a long period, silver has the propensity to cause
substantial tissue reaction and a tendency to corrode in
vivo. Steel was the next material of choice. Stainless
steel alloys such as 301 SS were used to manufacture
the earliest Drake and Yasargil type clips. Surgeons
have even fabricated clips from gold sourced from
dental supply stores. As the use of magnetic resonance
imaging (MRI) became popular, the demand for MR
compatible clips grew, leading to the use of special
alloys such as MP 35 N (Sundt Slim-Line), cobalt alloys
like Phynox (Yasargil FE) or Eligiloy (Sugita Standard).

10. • In current practice, both Yasargil and Sugita clips are made of
medical grade titanium. Titanium clips have minimal interference
with both computed tomography (CT) and MRI compared to
Phynox. Ceramic clips have also been created recently to further
reduce the chances of MR image degradation due to susceptibility
artifacts.
• Temporary and permanent clips are classified according to the
closing force they generate. This distinction is important when one
considers the need for a temporary occlusion of the parent or
proximal vessel prior to securing the aneurysm. The latest Yasargil
and Sugita temporary clips show a closing pressure of between
0.88–1.08N (90–110g) and 0.69N (70g), respectively. Permanent
clips have a closing pressure 1.27– 1.47 N (130–150 g, Sugita) and
1.47–1.96 N (150–180 g, Yasargil).

11. • The closing pressure is the lowest at the tip and
maximum at the pivot. Studies have shown that
the closing pressure could be dangerously high
near the pivot and could cause an aneurysm to
rupture even when a temporary clip is applied.
Over the past many years, aneurysm clips have
evolved to become safer; more versatile; and
show a rich variety of sizes, shapes, and
materials. The expanded armamentarium aids
the neurovascular surgeon to tackle almost any
aneurysm configuration.

12. Basic Principles of Clipping
• Clipping of an aneurysm requires planning and
deliberate dissection. A calm surgeon, sitting
down on an operating chair, resting his elbows
and hands in an ergonomic position can
facilitates minute changes in the angle of
visualization without taking the hands off. Sharp
arachnoidal dissection and gentle probing with a
rounded dissector reveal the anatomy of the neck
of the aneurysm, associated branches, and
perforators while avoiding the dome.

13. • Risky maneuvers like freeing a vessel adherent to the fragile dome of the
aneurysm or advancing a permanent clip is carried out after temporary
clipping to soften the aneurysm. The surgeon needs to see both sides of
the neck and the two clip blades at the time of application. The
microscope needs to be angled to achieve this objective. However, this
view does not usually show the tip of the blades once they are advanced
and closed. After application, the microscope is angled obliquely to verify
that the clip blades have passed the neck entirely. When the neck of the
aneurysm is squeezed shut by the clip blades, the diameter of the neck
increases by about 50%. Hence, the clip blades should be that much
longer (1.5 times the neck diameter). Incomplete neck closure at the distal
side of the aneurysm neck is the most common cause of persistent filling
of the dome. In most cases, the clip can be advanced to close the neck
completely. Very rare instances of persistent aneurysm filling through the
minute gap in the proximal part of a relatively short Yasargil or Sugita type
clip that was applied too far, has also been reported.

14. Different Types of Clips Used in
Various Aneurysms
• PCOM artery aneurysms
• Most PCOM aneurysms are clipped using a simple straight
clip. The PCOM artery usually arises proximal to the neck of
the aneurysms. A more ventrally pointing aneurysm may
require a right-angled fenestrated clip.
• MCA aneurysms
• MCA aneurysms are clipped in many ways: Simple clipping,
multiple clipping, fenestrated clipping and vessel
reconstruction. It is important to place the blades of the
clip parallel to the branches. In a broad-based aneurysm,
this may require a curved clip, matching the curve of the
bifurcation. A small residual neck can be clipped by an
additional small mini-clip.

15. • Anterior communicating artery aneurysms
• Inferiorly projecting aneurysms can be clipped easily by a simple
straight clip, taking care, not to take the contralateral A1 at the
distal end of the clip. Similarly, anteriorly projecting aneurysm is
tackled with a simple straight or curved clip. While clipping
superiorly projecting aneurysms, the ipsilateral A2 may come in the
way of the neck. One option is to manipulate a straight clip anterior
or posterior to the A2 closing it parallel to the communicating
segment. If that is not possible, a straight fenestrated clip may be
appropriate, saving the ipsilateral A2 in the fenestration. Posterior
pointing aneurysms are the most challenging, and typically require
an angled fenestrated clip, encircling the ipsilateral A1, A2, and/or
ACOM complex itself.

16. • Supraclinoid ICA aneurysms
• These aneurysms are clipped after drilling the anterior
clinoid process and cutting the distal dural ring to
completely visualize the neck. ICA-ophthalmic
aneurysms are usually clipped with a simple side-
angled clip.
• Sometimes one may have to take the ophthalmic
artery in the fenestration. In contrast, superior
hypophyseal aneurysms require a right-angled
fenestrated clip, taking the ICA within the fenestration.
It is important to preserve the PCOM and anterior
choroidal artery in this clipping.

17. • Basilar bifurcation aneurysms
• Superiorly projecting aneurysms are clipped
with a straight clip, parallel to both PCAs.
Similarly, anteriorly projecting aneurysms are
clipped with a lateral clip trajectory, with a
straight clip. With more posterior projecting
aneurysms, one may require a fenestrated
clip, taking ipsilateral PCA in the fenestration.