Fig. 15.1
Cerebral angiography AP (a) and lateral (b) views. Demonstrating occlusion of the distal RICA (thick arrow), just proximal to its bifurcation into ACA and MCA. The cerebral vasculature is not visualized. Irregularity in the lumen of the ICA is also appreciated (thin arrows), which probably was the source of the occlusive embolus. Clinical, CT, and MRI did not demonstrate as large a stroke as one would expect based on these images. LICA angiography (c) demonstrating crossflow across to the ACom to the contralateral ACA and MCA, explaining why the right cerebral infarct was not extensive
Intra-arterial rt-PA may be indicated for patients where angiography may be performed and treatment administered within 3 and 6 h after symptom onset with an NIHSS score of greater than 4, or those with an NIHSS score of greater than 20 and the ability to be treated within 6 h.
Posterior circulation strokes (Fig. 15.2) may be treated endovascularly for up to 24 h (due to a lesser likelihood of hemorrhagic conversion of infarct).
Fig. 15.2
a Left vertebral angiography manifesting occlusion (arrow). Right vertebral angiography (b) demonstrates adequate supply to the posterior circulation including left PICA, in the same patient. Consequently, intervention for the LVA occlusion was not required
Contraindications
Most contraindications are relative and have to be weighed against the risk of not intervening. These contraindications include:
Hemorrhagic infarct.
CT demonstrating hypodensity or mass effect consistent with evolving infarct of more than one-third of middle cerebral artery territory.
Recent major surgery.
Pregnancy.
When considering stenting, contraindication to anticoagulants and/or thrombolytics.
Preoperative Management
This is usually under the supervision of a stroke neurologist. Ensure the following:
Rapid transfer to a stroke center/facility with endovascular capabilities.
ABC’s.
Ensure patient has two intravenous lines, preferably 18G or larger.
Start monitoring BP, pulse oximetry, ECG, O2 saturation, cardiac rate and rhythm, respiratory rate.
Insert a Foley catheter.
Verify laboratory values including Platelet count, BUN, CR, APTT, PT/INR.
ß-HCG for females of reproductive age group.
Maintain MAP ≥90 mm Hg.
CT scan head, CT angiography (CTA) head and neck and where available, CT perfusion (CTP). (The use of CTP is currently not included in the stroke guidelines. One of the authors uses it, the other does not, relying on the therapeutic window.)
MRI head (select cases).
Be cognizant of renal insufficiency, diabetes, congestive heart failure, etc., in which case consider diluted nonionic contrast agent and maintain contrast load to minimum.
If the patient is within 3- to 6-h time window, and there are no contraindications start TPA (See below).
Chemical Recanalization
Abciximab (Reopro®, Eli Lilly and Co., Indianapolis, IN)
To lyse clots which appear to comprise of primarily platelets (L.D. loading dose of 0.25 mg/kg IA or IV over a few minutes, followed by continuous IV infusion of 0.125 µg/kg/min (max. 10 µg/min) for 12 h, then d/c.
Abciximab is usually administered when the arterial occlusion is consequent to a platelet plug. This may be iatrogenic, e.g., during intervention when platelet plugs may form over a wire and subsequently be shorn off when the catheter is advanced over the wire.
TPA
0.9 mg/kg IV (max 90 mg) with 10% of total dose administered as an initial IV bolus over 1 min, and the remainder is infused over an hour. This intravenous dose is administered within the therapeutic (3–4.5 h) window.
The maximum intra-arterial dose is 22 mg. It is independent of any previously administered intravenous dose.
Up to 20 mg of IA TPA can be administered with relative safety into each arterial tree.
In case of cranial sinus thrombosis (CST), usually 2–5 mg are administered IA through the thrombus and then an infusion started at a rate of 1 mg/h, usually for 12 h. If clot burden is still there on angiography, a longer duration of administration until the clot resolves is a consideration.
In CST, the infusion is prepared in a concentration of 1 mg/10 ml (0.1 mg/ml), for a rate of 10 ml/h.
Technique
Abciximab
Advance a microcatheter over microwire using appropriate views and position it just proximal to the iatrogenic clot. Administer 0.25 mg/kg IA over a few minutes. Preform angiography 15–20 min later to assess the results.
Direct the anesthesiologist/nurse to start the infusion at 0.125 µg/kg/min (max. 10 µg/min) for 12 h. This infusion may also be deferred until the arteriotomy site has been closed following completion of intervention.
TPA
Advance a microcatheter over microwire using appropriate views and position it in the affected artery distal to the clot.
Administer 1–2 mg TPA manually distal to the clot.
Then administer an infusion of 0.5 mg/ml at 20 ml/h (10 mg/h).
The infusion is prepared by mixing 10 mg of TPA in 20 ml on normal saline, resulting in a concentration of 1 mg rt-PA per 2 ml saline (or 0.5 mg/ml). Use an infusion pump for more precise administration.
Perform angiography every 15 min (following infusion of 2.5 mg TPA) as the catheter is gradually drawn back through the clot. Re-cross the lesion after each angiogram. If the artery is still occluded, inject 1–2 mg rt-PA manually and resume the TPA infusion.
Discontinue TPA if
adequate recanalization is achieved,
extravasation of contrast material is noted on angiography,
a maximum dose of 90 mg has been administered, or
the administered dose approaches the maximum dose without clinical or angiographic improvement.
It may be noted, since the introduction and success of stentrievers, mechanical thrombectomy is attempted as a first approach in intervention, rather than spending time on IA thrombolysis. TPA administration is more frequently being used as ‘clean-up’ procedure following thrombectomy.
Mechanical Recanalization
Indications and Case Selection
Ischemic stroke when the patient has failed IV-t-PA therapy.
Ischemic stroke when the patient is not a candidate for IV-t-PA therapy, e.g., greater than 3–4.5 h since onset of stroke, or significant risk with TPA or heparin usage, e.g., recent major surgery.
Contraindications
Hemorrhagic stroke, or when thrombectomy may result in significant hemorrhagic conversion of stroke.
CT demonstrating hypodensity or mass effect consistent with evolving infarct of more than one-third of middle cerebral artery territory.
Recent major surgery.
Pregnancy.
In case of stenting, contraindication to anticoagulants and/or thrombolytics.
Equipment
Choice of devices for stroke intervention.
Catheter wires.
Thrombectomy devices.
Stentrievers.
Merci.
Penumbra system.
Pronto device (for CST).
Drugs
0.9% NS + 20 meq KCl @ 75 cc/h (adjust to higher rate if needed to maintain target MAP).
Fentanyl 25–100 µg IV prn.
Versed 0.5–1 mg IV prn.
Devices
18G Single-wall needle.
6-Fr short sheath (10 cm, Pinnacle; Terumo Interventional Systems, Tokyo); Use 8 Fr or 9 Fr from outset, if there is a good chance of endovascular intervention with stentrievers, Merci® or Penumbra® systems.
Use a long sheath if the patient has tortuous vasculature.
Guide catheter: 6-Fr Envoy® MPC guide catheter (90 cm) or,
Merci® balloon guide catheter.
Neuron™ 070 guide catheter.
Diagnostic catheter: front angled catheter 5 Fr (Glidecath®; Terumo Interventional Systems, Tokyo).
Glidewire® (Terumo Interventional Systems, Tokyo).
Microwire (exchange length): Transcend EX 0.014 300 Floppy, or
Transcend EX 0.014 300 ES, or Synchro2 (soft).
For microwire thrombolysis: Excelsior™ SL 10 microcatheter.
Stentriever systems:
Presently, there are two products available in the US market. Both are comparable in usage and results. These are Trevo® (Stryker Neurovascular, Fremont CA) and Solitaire™ (ev3 Neurovascular, Irvine CA). One obvious difference between the two is that Trevo is visible fluoroscopically through its entire extent, while Solitaire has radiopaque markers at its proximal and distal ends with the intervening component being radiolucent.
Here the use of Trevo is described (Solitaire usage is very similar). Trevo has a modified proximal end that enables attachment of the Abbott Vascular DOC® guidewire extension. The guidewire extension makes it possible to remove or exchange a catheter, while maintaining the retriever in position. The extension can be detached, once the catheter exchange is complete.
For Using Trevo Stentriever
Trevo XP Provue retriever 4 × 20 (the most commonly used size).
Trevo Pro 18 microcatheter.
Merci Concentric balloon guide catheter.
Torque device and insertion tool.
For Using Merci® Retrieval System
Merci® balloon guide catheter.
Merci® microcatheter.
Merci® Retriever device (options: L4, L5, L6, X6, and KMini).
See Table 15.1 for appropriate microcatheter and retriever selection.
Table 15.1
Appropriate microcatheter and retriever selection
Merci retriever
L4
L5
L6
X6
KMini
Merci microcatheter
18L
18L or 18X
18L
14X
14X
Helix loop diameter (mm)
2.0
2.5
2.7
1.5–3.0
2.1
Helix length (mm)
2.5
4.5
4.5
7.0
2.5
Filaments
Yes
Yes
Yes
No
No
Resheathable (in vivo)
Yes
Yes
Yes
No
No
For Penumbra System™ (Alternative to Merci® Retrieval System)
Reperfusion catheter
Separator
Aspiration tubing (sterile)
Pump canister tubing (non-sterile)
Pump canister and lid
Pump filter
Use Table 15.2 and Fig. 15.3 for selection of the appropriate size.
Table 15.2
Catheter size
Vessel size
Reperfusion catheter + separator
<2 mm, e.g., M3
026 Reperfusion catheter/separator pair
2–3 mm, e.g., M2, P1
032 Reperfusion catheter/separator pair
>3 mm, e.g., ICA, M1, VA, BA
041 Reperfusion catheter/separator pair
Fig. 15.3
Various sizes of penumbra aspiration catheters and separators. Note that the separators are color coded. Their recommended usage in the arterial tree is also indicated
For angioplasty:
Gateway™ PTA balloon catheter (Size: ≤artery proximal and distal to the lesion).
Inflation device with manometer.
Stent: Wingspan™ Stent system (Size: = {or slightly oversized} the artery proximal and distal to the lesion. Length: should extend at least 2 mm beyond the proximal and distal aspect of lesion).
Rotating hemostatic valve (RHV) and adaptor: 2.
Syringes 60 cc, 10 cc (at least 3), 20 cc (at least 4), 3 cc (for ACT and angioplasty balloon preparation).
Three-way stopcock: 3.
Torque device.
Telfa strip.
Mandrel for shaping microwire tip.
Angioseal™ closure device.
Technique
Time is of the essence in stroke… work fast.
If neuroimaging (CT/MRI) and clinical scenario indicate mechanical thrombectomy with Merci® Retriever system, start out with a large (8 Fr or 9 Fr) sheath to save time.
In an elderly patient where there is a great likelihood of vessel tortuosity (including in the iliac region), consider a longer sheath (30–45 cm) or a shuttle sheath (90 cm; Cook Medical).
Gain access with 18G single-wall needle (instead of micropuncture, to save time) using modified Seldinger technique.
Insert the short sheath over J-wire (see Chap. 2, Specifics for micropuncture Technique section). Or, insert a longer sheath, e.g., shuttle sheath over a Glidewire® (Terumo®) or Bentson® (Cook Medical) wire, if the patients vascular anatomy is known to be tortuous.
Secure sheath in position using 2-0 silk suture.
Diagnostic Angiography
Due to the frequent performance of CTA during stroke management, these days diagnostic angiography is usually unnecessary and one can directly proceed to intervention. However, if needed, the technique is as follows:
- (a)
Rapid
Irrigate a 5-Fr pigtail catheter with heparinized saline and attach it to an RHV, which in turn is attached to a three-way stopcock connected to a continuous heparinized saline flush and a neonatal transducer, enabling a flow rate of 30 ml/h.
Irrigate the glidewire in its containing ring and then insert it into the pigtail catheter.
Introduce the catheter with glidewire into the sheath and once in the sheath advance the glidewire to lead the catheter.
Under fluoroscopic guidance, with the glidewire leading, navigate to the ascending aorta.
Remove the glidewire from the catheter and store it in heparinized saline basin.
Center the image intensifier or detector over the patient’s head, ensuring both right and left sides are in the field.
The magnification should be decreased so that both the cervical and cerebral vasculature are in the field.
Angiography is performed in AP view.
Perform angiography with contrast injection at a rate of 20 ml/s for a total volume of 30 ml.
The above method of angiography will demonstrate the cervical and cranial, as well as, anterior and posterior circulations concurrently for a rapid diagnosis of the site of lesion.
Withdraw and remove the pigtail catheter. Disconnect it from the RHV. The RHV can then be used for the guide catheter.
- (b)
Standard
In case the clinical symptomatology is indicative of the location of lesion, proceed with a 5-Fr front angled catheter (Glidecath; Terumo®, Tokyo, Japan) to perform diagnostic imaging, instead of above-mentioned aortic arch injection.
Perform angiography of the involved side, e.g., if patient has left hemiparesis, study the right carotid vasculature.
Alternatively, diagnostic imaging may be performed with a guide catheter, e.g., Envoy (Cordis Endovascular Systems, Miami Lakes, FL), potentially eliminating the need to switch catheters at the time of intervention.
Use at least a 6- or 7-Fr guide catheter, in anticipation of intervention. This will save the step of exchanging for a larger-sized guide catheter.
After the diagnostic images, maintain the tip of guide catheter in the artery of interest, e.g., CCA or ICA.
In case of ischemic stroke, usually 4-vessel angiography is not required at the outset.
If any difficulty is encountered due to vessel tortuosity, don’t waste time and quickly proceed to using a Simmons 2 or Head hunter H-1 type catheters (Terumo Interventional Systems, Tokyo) to complete the diagnostic imaging.
After diagnostic imaging, if difficulty was encountered in vessel selection with the diagnostic catheter, use exchange length wire (260–300 cm) for replacing the diagnostic catheter with a guide catheter.
If the patient does not have a difficult vasculature, an OTW catheter exchange is unnecessary and simply withdraws the diagnostic catheter. Using glidewire advance the guide catheter into its position in the usual manner.
If OTW exchange is needed, it is performed as follows:
Activate the hydrophilic coating of EL Glidewire (Terumo®, Tokyo, Japan) or Bentson (Cook Medical Inc., Bloomington, IN) wire, by wiping its entire length with a moist Telfa.
In case an EL Bentson (200 cm) wire is used, be sure to shape its tip into an angle (e.g., 45°). Otherwise, considerable difficulty may be encountered in vessel navigation.
Loosen the knob of the RHV and introduce the wire into its hub and then advance it through the catheter.
Under fluoroscopic guidance, advance the tip of the wire into the target vessel, e.g., ICA (preferable, to save the steps involved in gaining ICA access later) with enough wire distal to catheter tip to maintain purchase.
Under fluoroscopic guidance, withdraw the diagnostic catheter while maintaining the wire tip in position. Take care that the wire is not inadvertently advanced into the intracranial ICA, or retracted resulting in loss of purchase.
Discontinue fluoroscopy once the diagnostic catheter is outside the patient.
Continue to ensure the wire does not move.
Preparation of Guide catheter
Detach the diagnostic catheter from the RHV and replace it with a 6-Fr Envoy® or Concentric balloon guide catheter.
Ensure that the guide catheter and the attached RHV with its saline flush system are free of any air bubbles.
Ascertain all connections are secure and will not fall apart during procedure.
Leave the third port of the stopcock (which is perpendicular to RHV sidearm) for contrast administration, etc.
Insertion of Guide catheter
Introduce the tip of the guide catheter over the proximal tip of wire and insert it into the sheath.
Using fluoroscopy, ensure that the distal tip of the wire remains in its position and is not inadvertently advanced, or retracted.
Advance the guide catheter into the ICA and position it in the vertical cervical ICA segment, or if needed, even intracranially in the cavernous segment, if safely possible. Sometimes due to vascular tortuosity or stenosis of the ICA, the guide catheter can only be positioned in the CCA.
Once the guide catheter is in place, remove the wire while wiping it with wet Telfa and store it in a basin with heparinized saline.
Note: sometimes the vessels are so tortuous that it may be best to leave the Simmons 2 catheter in as the guide catheter.
If the initial decision is to perform thrombolysis, using the microwire proceed as follows.
Preparation of Microcatheter and Microwire
Take the sterile packaging containing the Excelsior SL 10™ (Stryker Neurovascular, Fremont, CA) microcatheter out of its packet and place on preparation table using sterile precautions. Conversely, may use Rapidtransit (Codman) or a similar catheter as well.
Flush the protective hoop bearing the catheter with normal saline.
Take the catheter out of its protective hoop.
Remove the shape maintaining stylet out of its distal tip.
Flush the catheter with normal saline by attaching a syringe to the proximal hub of the catheter.
Attach the microcatheter to an RHV that in turn is attached to a continuous heparinized saline flush.
Take the sterile packaging containing the 0.014″ Transcend™ wire out of its packet and place it on preparation table using sterile precautions.
Irrigate the wire in its protective hoop, using the portal provided.
Then gently introduce the distal tip of the microwire through the RHV into the catheter without distorting the shape of the tip. Advance the wire through the catheter until about 5 cm of it protrudes beyond the catheter tip (alternatively, the wire may be backloaded into the microcatheter by introducing the stiffer end into the catheter tip and pushing it, until the stiff end emerges from the loosened knob of the RHV at the other end.
Grab the emergent end and pull, until only about 5 cm of wire protrudes beyond the catheter tip.
Using the provided mandrel, shape the distal tip of the wire to enable easier navigation through the patient’s cerebral vasculature.
Ensure that there are no air bubbles in the microcatheter system.
Insertion of Microcatheter
Loosen the knob of the RHV connected to the guide catheter.
Introduce the distal tip of the catheter into the RHV of the guide catheter.
Once the microcatheter is within the guide catheter, advance the microwire such that it leads the microcatheter.
Tighten the knob of the guide catheter RHV just enough so that back bleeding is prevented, while the microcatheter and wire can be manipulated easily.
Keep the entire system straight.
Advance the microcatheter until the tip of the wire is just proximal to the tip of the guide catheter.
Thrombolysis
Select working views by performing cerebral angiography through the guide catheter.
Attach torque device to the proximal (outside) end of guidewire.
Using roadmap guidance advance the guidewire, using the torque device to rotate the wire as needed while it is advanced.
Then advance the microcatheter over the wire, ensuring that the wire is leading the catheter at all times.
Continue to alternatively advance guidewire and microcatheter, until the target vessel is reached.
Attempt to cross the clot with the guidewire and then slowly withdraw the wire while rotating it, to disrupt the clot.
Once wire is proximal to the clot, perform angiography to assess results.
If needed, perform additional passes with the wire to achieve clot lysis.
Consider supplementing mechanical thrombolysis with TPA or abciximab (see ‘Chemical Thrombolysis’ above).
Perform angiography alternatively with thrombolysis to assess re-establishment of blood flow.
Consider giving the tip of the microwire a ‘J’ shape. This will diminish the likelihood of the tip perforating through the vessel wall (consequent to the inability to visualize the occluded vessel segment). The J tip will also diminish the likelihood of inadvertent selection of branches such as ophthalmic, or posterior communicating artery.
Note: Given the availability of effective devices such as stentrievers over the past few years, in case of stroke we recommend immediately proceeding to the same in the IR Lab. Mechanical thrombolysis (supplemented with chemical thrombolysis and aspiration through microcatheter) is a consideration when thrombectomy with stentrievers is not an option.
Thrombectomy
- I.
To Perform Thrombectomy Using the Trevo System
The Trevo Kit has the following components:
Trevo XP Provue retriever 4 × 20 (the most commonly used size)
Trevo Pro 18 microcatheter
Torque device and insertion tool
Merci Concentric balloon guide catheter.
Indications and Case Selection
Patients within 8 h of experiencing ischemic symptoms
Patients who are ineligible for IV TPA
Patients who fail IV TPA therapy
One can use CT perfusion study demonstrating a viable penumbra as an indication for intervention. Or, go with the above-mentioned time window.
Contraindications
Radiologically demonstrable large ischemic infarct.
More than 8 h since onset of stroke in anterior circulation and 12 h for posterior circulation (relative contraindication), unless CTP shows viable penumbra and the completed infarct to be less than one-third of the hemisphere (Fig. 15.4a–h).
Fig. 15.4
A 66-year-old who presented with left hemiparesis and dysarthria. At presentation, the onset of symptoms had been for more than 6 h. a A CT scan demonstrates the hyperdense clot (arrow) in right middle cerebral artery (MCA). The CTA b demonstrates the abrupt cutoff of MCA at same site (arrow). A clot can be appreciated ahead of the cutoff. c A coronal reconstruction better demonstrates the MCA cutoff (arrow). Also noticeable is the paucity of MCA branches when compared to the contralateral side. The CTP performed d demonstrates significantly attenuated cerebral blood flow of right hemisphere compared to left. The arrow indicates an area where there is no flow (refer to the color code bar on the right side of the image). However, the cerebral blood volume (CBV) is not significantly impacted other than in the previously indicated area with no flow (e). The mean transit time (MTT) in the right cerebral hemisphere is increased (f) when compared to the unaffected left MCA territory. There is clearly a large mismatch between CBV and MTT. These images confirm an area of large penumbra that is potentially salvageable. Angiography performed (g) confirms the MCA occlusion (arrow). Due to contrast reflux, external carotid branches are visible (asterisk). A Trevo stentriever was used for thrombectomy, resulting in successful clot removal on first pass (h)
Preparation of Balloon Guide catheter
Take the Merci® balloon guide catheter out of its packet and place on preparation table using sterile precautions.
If diagnostic angiography was done first, simply detach the diagnostic catheter from the RHV-saline flush system and use the flush system for the balloon guide catheter. Ensure the entire system is free of air bubbles.
Otherwise, prepare the system as follows:Related posts:
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