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Carotid angioplasty: techniques with and
without cerebral protection
Oscar A. Mendiz
Dpto. de Hemodinamia e Intervenciones por
ICyCC. Fundación Favaloro.
After big randomized trials results comparing
surgical and medical treatment for carotid obstructions were known, Surgical
Endarterectomy is considered as a first choice treatment for this high prevalent and with
severe consequences disease1-2-3-4
However, as in other vascular territories, in the last years endoluminal treatment has reached more importance, and after big international series results were known, carotid angioplasty has become a conventional surgery alternative 5-6-7.
One of the more important carotid angioplasty limitations has been the threat possibility of micro or macro embolization related complications. This phenomena has been demonstrated that occurs with certain frequency, but with low clinical expression rate.
Cerebral Protection devices were developed with the aim of improving conventional carotid angioplasty results, which has been the more frequent technique utilized up to now, and with which were done the biggest known series.
I will try to summarize each technique, describing different devices and giving my opinion about possible advantages among them.
B- Carotid angioplasty without cerebral protection:
We can include under this arbitrary denomination, a
great deal of techniques which share the non use of any element which would avoid cerebral
embolization with vascular or plaque released material.
Angioplasty technique changes depending on selected vascular access; the most used is the femoral access, but brachial access is also described (humeral) or direct common carotid artery puncture (forward or retrograde depend on lesion localization).
For its more frequent use, I will refer only about femoral approach. In this way two different techniques are possible to be used, which using guiding catheter and a long introducer sheath, with similar characteristics between them.
1- Angioplasty by Femoral Approach:
a- With Guiding Catheter Technique:
After puncture has been done, with a 5~6 French catheter
(Judkins with right coronary artery shape, Vitek, Simons, left internal mammary artery
angiographic or Hockey Stick) to be treated the side common carotid artery is
catheterized. Basal extracraneal angiography is taken, and employing as a reference to
floppy (0.035 inch) wire advance up to external carotid artery followed by the catheter
advance over this wire.
Later this wire is exchanged by a rigid one (0.035" and 300 cm. in length exchange wire) which is placed at the external carotid artery. Eight or ten French, Multipurpose or right coronary artery shape, guiding catheter (trying to obtain the best possible coaxiality) over a 6 French catheter (avoiding vessel wall damage) is advanced.
After withdrawing exchange wire, two orthogonal extracraneal and one antero-posterior or homolateral oblique with cranial inclination basal projections are taken.
Lesion is crossed with a steerable floppy wire (usually 0.018") that is placed at the intracranial internal carotid artery avoiding positions further than clinoid apophysis (to avoid spasm). An over the wire balloon is advanced to dilate the lesion, with enough pressure to make disappear balloon indentation, generally 4.0 mm. in diameter and 20 mm in length is used. A stent is implanted after dilatation with the aim of reaching 1/1 stent-vessel diameter relationship. Primary stent is done without balloon predilatation.
Following stent implantation its expansion is optimized (if were necessary) using optimal balloon diameter. If residual obstruction is less than 30%, the procedure would finish; but if not, more pressure or grater diameter balloon (0.5 or 1.0 mm.) is used for a new dilatation.
More frequent used stents had been: balloon expendables (Palmaz, Palmaz-Schatz, Magalink, etc.) which 1/1 balloon-vessel relationship is employed, self-expandibles (i.e. WallStent, etc.) which diameter generally is calculated according to common carotid artery diameter; and thermo-expandibles (i.e. Memotherm, etc.) which diameter is similarly calculated to the previous one.
b- Angioplasty with Introducer Set:
After common femoral puncture a 7~8 French and 90-100 cm. in length Sheath is introduced, target vessel is catheterized with a selected catheter and is over the wire forwarded proximal to the selected lesion position where would be used as a guiding catheter following the previous described technique.
2- Angioplasty by Brachial Approach:
It is performed by puncture or humeral artery dissection using a long flexible 7 French introducer set [type Arrow Flex (Weesp, The Netherlands)]. This technique is used only in exceptional cases.
3- Angioplasty by Direct Puncture:
It is a non spread used technique; which is done by
forward or retrograde direct common carotid artery puncture (depending on lesion
localization) under "road-mapping" control after a dye injection through a
catheter placed at the aortic arch or eventually with a Doppler-needle.
The same technique as previously described is followed later. Possible disadvantages are; direct plaque puncture possibility, common carotid artery dissection, potentially dangerous cervical haematomas, stent crush during manual compression at introducer set retrieval, etc. All these elements lead to be an uncommon used technique by the majority of the interventionists.
Embolization is possible to happen in all this "without protection" techniques during every maneuvers, and taking care in the technique is with which decreases this possibility.
Previous treatment (2~3 days before procedure) with antiplaquetary agents as Ticlopidine, Clopidogrel or Aspirin and case selection, because of thrombus containing or ulcerated lesions, echolucent (lipidic) and at the bifurcation plaques has major possibility of embolization, also decrease before mentioned possibility;8.
C- Carotid angioplasty with cerebral protection:
Carotid Angioplasty with cerebral protection, which has
Dr Jaques Théron (CHU, University Hospital, Caen, France) as a pioneer, has the aim of
decreasing during procedural maneuvers released material possibility of cerebral
embolization, producing severe side effects.
Protection techniques are different according to the used devices, which would be classified in two different groups: 1- Devices producing blood flow stop (i.e. Occlusive balloon devices), 2- Devices which maintain some blood flow through it. (i.e. "filters").
1. Stopping Flow Devices ("Transient Endovascular Clamp").
There are systems that usually have a distal balloon,
that block blood flow when is inflated, decreasing or avoiding same material brain
These devices have a complete flow blockage, during different times depending on the technique, as a potential disadvantage; however, it has been demonstrated that patients have good tolerance in a great number of seconds transient occlusion.
Transient occlusion intolerance may occur with major frequency in patients with congenital anomalies or acquired Willis Circle disease or severe contralateral disease. This is the reason why a completely four supra-aortic vessels angiography study is important.
a- Thérons System: First bibliographic reference
about this device belong to 19909 Théron and col. presentation with a bigger
Its a triple coaxial catheter which allows internal carotid artery occlusion when it is placed higher than target lesion, avoiding detritus pass which is retrieved later by aspiration or saline flush.
This technique consists in placing a 8~9Fr guiding catheter as a conventional technique; followed by crossing the lesion with the micro-catheter which has attached a distal latex balloon that is placed distal to the target lesion.
Over the micro-catheter a balloon angioplasty catheter is advanced. After each dilatation aspiration must be carried-out and or flushing with heparinazed saline solution if balloon is scheduled to be deflated (staged procedure).
Main limitations are; difficulty to visualize non radiopaque balloon, furthermore it is a non steerable system because it is non possible to cross some lesions.
In these cases, lesions are possible to cross with a coronary angioplasty steerable guidewire (.014") used at interventional cardiologist procedures, followed with coronary balloon predilatation and protection device can be used during the time that the following procedure last.
A series with 259 carotid angioplasty was reported by Théron, 136 were done under cerebral protection. One of two embolic reported events occurred during stent implantation without cerebral protection (not possible to do under protection), and other one happened 6 hours after the procedure11.
Difficulty in utilization together with loss protection benefits conscious among interventionist when this technique began to be used, have been one of the most important use limitations for spread utilization.
b- PercuSurge System :
It is a set of elements designed to endovascular blood flow clamp with an elastomeric balloon attached to distal .014" or .018" wire "PercuSurge GuardWireä System" (Figure N°1).
Guidewire has the following characteristics: it is a
steerable, floppy end with a good torque Nitinol guidewire. This is wire made up by an
hypotube system which connects with distal balloon and allows its insuflation and
deflation through a proximal placed lock system which is open or closed by a special
ad-hoc adapter system (Microsealä ).
This valve system allows to use the wire as it is usually done, allowing to do rapid exchange or over-the wire technique.
It is a material which has to be used taking great care about the possibility of folding which would make difficult the inflation-deflation balloon mechanism. A third element is a monorail aspiration catheter ("Exportä "), which is used to remove the detritus trapped by the balloon (Figure N°2). Insuflation time may oscillate according to patient tolerance and planned strategy (staged or continuous procedure).
Finally, two flushes with heparinized saline solution are generally done, to flush the potentially remaining particles which flow to the external carotid artery.
Distal lesion vessel diameter has to be considered, so that the internal carotid artery can be occlude, with good wall vessel apposition, by the biggest balloon available. The greater vessels diameter must be non grater than 5.5 mm.
Residual angioplasty procedure is not different from habitual one.
In summary; it is a relatively easy to use device which would increase carotid angioplasty use with protection (Figure N°3) y (Figure N°4).
Potentially flow clamp intolerance in patients with Circle of Willis or contralateral disease, as it can occur with all these group system devices, is the major limitation.
Device Experience: Thirty five procedures in 31 patients without neurological complications were reported by M. Henry and col.. Balloon inflation was well tolerated in 34 procedures (was referred contralateral occlusion in a patient who did not tolerate this procedure). Balloon was inflated during all the procedure in 29 cases .
At Fundación Favaloro, we are participating in a multicentric prospective registry (CAFE) which is leaded by Dr. Patrick Whitlow (Cleveland Clinic Foundation. USA) and where 31 patients were included up to May 1999; only one patients had first inflation balloon intolerance (transient disartry) with well tolerance for the following part of the protected staged procedure.
There were not any neurological complications during all 30 days cases follow-up. (Figure N° 5) y (Figure N° 6).
c- Katchel System:
Made-up by a balloon attached to the tip of a guiding
catheter which block blood flow when is insufflated at the common carotid artery, allowing
to do conventional technique angioplasty while blood flow is reversal to the external
carotid artery where detritus would flow13 .
It is an easy system to use but difficult to apply at bifurcation lesions which represent an important percentage of those. In the other hand, complications incidence of reported series are about 4.6%, which is similar to unprotected series.
This technique could be used together with distal occlusive devices.
d- MEDICORP Henry-Amor-Frid-Rüfenacht
It is similar to Théron and PercuSurge devices because it is a micro-catheter with a near distal attached balloon.
2. Protection Devices Which Allow distal flow (Filters).
Keeping blood flow is the main theory advantage of these
devices. Filters retain small particles depending on the porous size. It is a not well
known amount flow remaining when the filter became filled with trapped particles.
These devices are less advanced than balloon protection system and serial clinical results are not known.
a- Angioguard Emboli Capture System :
It is a distal porouse membrane attached to a Nitinol guidewire by a self containing structure which is folded inside a low profile capture catheter. The distal end of the wire is flexible and when the device is deployed (withdrawing the sheath), it takes the shape of an umbrella allowing particles capture (Figure N°7). This umbrella is possible to be fold again capturing particles when the procedure is finished (Figure N° 8, N° 9 y N° 10).
Flow difficulties because the filter is filled with
particles during the procedure must be checked. In these circumstances the filter has to
be changed following the previous description.
Some limitations are: high profile which can difficult critical obstructions crossing, impossibility to aspirate some particles which could remain attached to the vessel wall and could embolize, different devices wall apposition, etc.
This device has been only unfrequently used by our team in a feasibility study led by Dr. Jay Yadav (Cleveland Clinic. USA) (Figure N°11 y N°12).
We have not enough information about other filters that
had been used by Dr. Gary Roubin for descriptions (Mednova ).
We can only say according with the picture, that it has a bigger wall apposition that can decrease particles cross between the filter and the vessel wall.
Carotid angioplasty with cerebral protection devices
have recently been introduced to the clinical practice and can possibly decrease
embolization related complications rate which may expand indications and technical
Cerebral Protections benefit must be demonstrated in a huge study with a great deal of patients.
E- References:1. North American Symptomatic Carotid Endarterectomy Trial collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. NASCET Collaborators. N Engl. J Med. 1991;325:445-453.
To Dr. Hugo F. Londero for manuscript correction and Mrs. Elena Maria Perez Alonso for English translation collaboration.