Endovascular Treatment

C O N T E N T S

8.1Techniques of

Transvenous Catheterization 189

8.1.1 Inferior Petrosal Sinus Approach 191

8.1.2Alternative Approaches

8.1.3Other Techniques 197

8.2Embolic Agents 197

8.2.1Polyvinyl Alcohol (PVA)

8.2.2.1Platinum (Non-detachable) Pushable Microcoils 198

8.2.3Liquid Embolic Agents:

Cyanoacrylates (N-butyl-cyanoacrylate, Acrylic Glue, HistoacrylTM,

TrufillTM n-BCA, GlubranTM) 204

8.2.4Onyx™ (Ethylene-Vinyl Alcohol Copolymer) 205

8.2.5Stents 206

8.3Results of

Transvenous Embolizations 208

8.3.3Cases Reports 209

8.3.3.3 Case Report III: Approach via the Thrombosed Cavernous Sinus 215

8.3.3.4Case Report IV:

Transfemoral Cross-Over Approach

via the Facial Vein and SOV 215

8.3.3.5Case Report V: Transophthalmic Approach

(Cannulation) via the SOV 220 8.3.3.6 Case Report VI: Direct Puncture

of the SOV 220

8.3.3.7 Case Report VII: Direct Puncture of the Sylvian Vein After Craniotomy 225

8.3.4Case Illustrations 225

8.4.1Approaches 228

Ophthalmic Vein Approach 232

8.4.1.4 Approaches via the Middle Temporal Vein or the Frontal Vein 233

8.4.1.5Transfemoral Superior Petrosal Sinus Approach 234

8.4.1.6Transfemoral Pterygoid Plexus Approach (PP Approach) 234

8.4.1.12 Sylvian Vein Approach: Combined Surgical/

Endovascular Treatment 251

8.4.2Embolic Materials 252

8.4.2.1Particles 252

8.4.2.2Coils 252

8.4.2.3NBCA (HistoacrylTM, GlubranTM, TrufillTM) 256

8.4.2.4Ethylene-Vinyl Alcohol Copolymer (OnyxTM) 257

8.4.2.5 Stents and Covered Stents 259

8.4.3Anatomic Results, Clinical Outcome and Complications of Transvenous Occlusions

and Transarterial Embolizations 260

8.5Conclusion 267

References 267

8.1

Techniques of Transvenous Catheterization

(Figs. 8.1–8.4)

Manual techniques of catheterization and embolization may differ from center to center and vary significantly between operators. The following descriptions are based on the author’s personal experiences

gained over more than a decade performing EVT in cerebrovascular lesions. Although mainly based on subjective manual handlings and personal preferences, these accounts may be beneficial, especially for younger colleagues. As for most endovascular procedures in the treatment of cerebrovascular lesions, the embolization of DCSFs is performed under general anesthesia, preferably under supervision of an experienced neuroanesthesiologist. Transvenous

catheterizations and embolizations are often lengthy procedures (2–4 h), during which the typically elderly patients would have difficulties remaining still on an angiographic table. General anesthesia with endotracheal intubation is therefore widely used in most centers in the world, as it also allows for safer monitoring and easier management in cases of intraprocedural complications such as rupture and hemorrhage.

8.1.1

Inferior Petrosal Sinus Approach

(Case Reports I–III, Fig. 8.3)

After arterial and venous femoral punctures and placement of 6-F introducer sheaths, an intravenous bolus of 50 IU/kg of body weight heparin is administered. Monitoring is routinely performed in most centers to keep the activated clotting time (ACT) at a level of approximately 250–300 s or 2× above the normal level.

A 4-F Headhunter 1 catheter (H1, Cordis, Miami, FL) is advanced into the ECA or ICA on the side of the dominant fistula supply to allow for road mapping and control injections throughout the procedure. A 5-F or 6-F angled guiding catheter (e.g. Envoy, Cordis Endovascular, Miami Lakes, FL) is placed in the IJV on the side that shows dominant drainage, or that looks most promising on the diagnostic angiograms. The catheters are flushed with heparinized saline (1500 IU per liter). Arterial and venous femoral punctures may be performed unior bilaterally (Fig. 8.13).

Alternatively, a direct stick of the jugular vein may be used, especially in cases with a thrombosed jugular vein on the fistula side. Because the entire catheterization system becomes shorter and provides better support for a supple microcatheter, a direct jugular stick makes microcatheter navigation through the IPS easier. A microcatheter may even be navigated directly through a 4-F or 5-F sheath when the IPS is widely open. The less access tools and devices are used, the easier the technical part of the procedure is, including deployment of coils, glue or a catheter exchange. The guiding catheter should be advanced close to the jugular bulb for performing phlebograms using either manual injections (20-cc syringe), or a power injector. If the anatomy looks abnormal, or the IPS appears thrombosed or is absent, contrast injections should be repeated from different positions and combined with a 3D phlebogram. Changing the position of the guide may be helpful, because in some cases the IPS may terminate at a lower level or even outside the skull base, and thus will be missed on standard 2D angiograms as seen in Fig. 7.37 (Benndorf and

Campi 2001b; Calzolari 2002).

If the IPS is not identifiable on either side, even after repeated phlebograms, careful image analysis is crucial in order to identify the small “notch” or a stump that is often the only residual filling of a thrombosed sinus (Figs. 8.3, 8.4, 8.14). This should include diagnostic arterial injections, particularly in

cases in which there is no posterior drainage, or the IPS is thrombosed. In those cases, the sinus may be wide open, utilized as an efferent vein by the normal cerebral venous drainage, and in fact representing a feasible transvenous approach (Case report III). If the IPS can be identified, retrograde catheterization is readily performed using a small hydrophiliccoated microcatheter, such as a 2.6-F FasTracker 10, (Boston Scientific, Fremont, CA).

Braided, reinforced microcatheters such as the 2.4-F Tracker Excel-14, 1.7-F Excelsior SL 10 (Boston Scientific, Fremont, CA) or the 3.0-F Rapid Transit 18 (Cordis, Endovascular, Miami Lakes), advanced over a 0.012s, 0.014sor 0.016s guidewire, usually allow easier navigation through the IPS and the CS, especially in cases, where the contralateral CS (cross-over) needs to be reached. Reinforced microcatheters are more stable throughout the procedure, an important factor in achieving a dense coil packing in the fistulous compartment. They also show fewer tendencies to kink, which is advantageous when using larger coils. An experimental study showed that even some reinforced catheters, such as the Rapid Transit 18 (Cordis Endovascular, Miami Lakes, FL) may develop luminal irregularities in a curved model that may create high resistance for embolic agents (Kiyosue et al. 2005). Significant friction may result when pushing fibered coils (Case Report IV).

In cases where the IPS cannot be identified with certainty, the residual “notch”, if visible, should be catheterized very gently with a small, hydrophilic guidewire. For this purpose, the 0.012shydrophiliccoated wire (Headliner, Terumo Corporation, Tokyo, Japan) is considered the most suitable guidewire to be use. It is a highly flexible, kink-resistant wire with a super-elastic nitinol core providing a 1:1 torque ratio, and has a 20-mm gold coil at the tip for enhanced radiopacity (Fig. 8.2). The Headliner has a superior lubricity and is available in 200 cm length in various pre-shaped tip configurations such as 45º, 90º, 1.5-mm J-Tip angle and double angle.

Some operators may prefer the Synchro2 wire (BSC, Natick, MA) that is available as 0.014s hydrophilic guidewire (external diameter 0.36 mm), or 0.010s guidewire (external diameter 0.3 mm) with pre-shaped platinum-tungsten alloy tips. The proximal portion is coated with a polymer (Polytetrafluoroethylene, PTFE) to enhance tracking and manipulation. An alternate choice is the Mirage, a 0.008s hydrophilic coated guidewire (0.20 mm) manufactured by MTI (Microtherapeutics, Irvine,

CA; Fig. 8.11). Another new development is the steerable guidewire Watusi (Micrus Endovascular Corporation, San Jose, CA) available in 0.014s(0.36 mm), made of stainless steel with a hydrophilic coating of the distal 40 cm. The smallest guidewire currently available is the 0.007s Sorcerer, (Balt Extrusion, Montmorency, France), a hydrophilic nitinol wire. The choice of microguidewires and microcatheters depends, to a large degree, on personal preferences, as well as on the type and level of acquired manual skills.

Using the microcatheter, the Headliner should be advanced only a few mm into the thrombosed IPS and then exchanged for a more stable hydrophilic coated guidewire such as the Transend 0.014s (Boston Scientific, Fremont, CA). This guidewire provides more stability to advance the microcatheter, while its tip is less flexible than that of the Headliner. The technique, utilized by the author to pass a thrombosed IPS, is to alternately and slowly advance both guidewires with the help of the microcatheter towards the posterior CS. It requires patience and full concentration and should be performed by an experienced operator. Aggressive or forceful manipulations may cause rupture of the IPS. For advancing a catheter through an irregular, stenosed, or even occluded sinus, the following technique proved particularly useful:

The guidewire is advanced not with a straight end, but instead with a loop that is formed within the narrowed lumen by bending the tip. Such a distal shape can be navigated much more easily than one would expect as it adapts better to an irregular lumen than a straight guidewire. It gets less entangled in small septi or stenotic segments of the trabeculated cavernous sinus structure.

This method, also called the “Loop Technique” (Figs. 8.3, 8.15, 8.20, 8.17), published earlier, has been used since with great success (Benndorf et al. 2000a), and has been adapted by others (Cheng

et al. 2003). A Terumo guidewire such as the Head- liner-12 with a pre-shaped 90º angle or double angle is particularly easy to form.

In order to avoid unintentional catheterization of bridging or pontine veins and to prevent perforation with subsequent intracranial hemorrhage, as reported by some authors (Halbach et al. 1988; Oishi et al. 1999), the simultaneous use of bi-plane “blank road mapping” and fluoroscopy of the native background are helpful.

When the posterior CS is approached through the IPS, it is usually possible to navigate the microcatheter into the anterior compartment and its connection with the SOV without difficulties. It is advisable to bring the microcatheter as close as possible to the SOV, preferably in its first segment. Coil deployment should begin within the SOV approximately 2–3 mm before its entry into the CS. This initial coil positioning is crucial to avoid increased drainage of the AV shunting into the SOV and ophthalmological deterioration. On the other hand, coils deployed in the anterior SOV (2nd or 3rd segment) may cause thrombosis and occlusion of the entire vein with blockage of the central retinal venous drainage leading to serious clinical consequences. To achieve dense packing from the beginning, it is wise to start with a coil size that can be easily stabilized in an enlarged SOV (e.g. 5 mm/15 cm). Three-dimensional or complex coils may also be used to create a basket that, similar to aneurysms, is subsequently filled with smaller and softer coils (Fig. 8.5). The more stable this initial packing within the proximal SOV or at the CS-SOV junction is, the better it may be used as a scaffold for subsequent coils. It will allow a dense packing of the CS, without the risk of dislodging coils into the draining vein. Commonly, the coil placement is performed from anterior to posterior to keep the access through the IPS free until the end of the procedure. This is a useful strategy because there is always the chance that coils get inadvertently placed early dur-

ing the procedure in the posterior CS, or even in the IPS. If this happens, before the actual AV shunt is occluded, complete packing of anteriorly located fistulas may become difficult, or the entire procedure may be jeopardized. Losing access to the CS or to a fistulous compartment in cases of an incomplete occlusion creates the risk of rerouting the drainage

towards cortical veins, causing cortical venous hypertension and possibly hemorrhages.

In cases with drainage towards the contralateral side of the fistula, the microcatheter should always be advanced there first. Such a “cross-over” approach via the intercavernous sinus allows blocking the drainage before withdrawing the catheter and pack-

ing coils at the fistula’s side (Fig. 8.15, 8.17, 8.22). This helps the operator to avoid leaving fistulous compartments behind that usually require more challenging catheterizations later on. Moreover, this is crucial in cases with bilateral fistulas, especially when the CS approach is possible from only one side (Fig. 8.22). Failing to occlude the contralateral fistula side first

may result compartmentalization, and second may complicate the management of the patient.

If cortical drainage is present, the most crucial part of the procedure is to block the connection between the CS and the cortical vein at the beginning of the occlusion, even before placing coils into the SOV (Fig. 8.4). Only such blocking will prevent per-