TECHNICAL CONSIDERATIONS FOR CAROTID ARTERY STENTING

							                            PATIENT FORM FOR CAROTID ARTERY STENTING
                             Technical Aspects of Carotid Artery Revascularization

Patient Name______________________ Phone Number: _______________ Date: ___________
Surgeon:__________________________ Referring MD: ________________________________

TECHNIQUE:

       1.   Complete neurological history and examination, including a baseline NIHSS.
       2.   Baseline brain CT or MRI.

       3.   Baseline laboratory values, including hemoglobin and hematocrit levels, serum creatinine,
             BUN, electrolyte levels, PT and PTT times, as well as preprocedural electrocardiograms
             and chest x-rays.
       4.   Fasting from midnight before the procedure. Consider withholding antihypertension agents
             due to the carotid bifurcation-related hypostension during the procedure.
       5.   Discontinue coumadin 3 days before procedure.
       6.   Patients with renal disease are admitted 1 day prior for intravenous hydration. Patients with
             renal compromise are also given a sodium bicarbonate renal failure infusion at the time of
             the procedure. (177 mEq sodium bicarbonate in 1000 mL of d5w. Bolus infusion of 3
             mL/kg per hour for 1 hour before going to the vascular lab. Followed by an infusion of 1
             mL/kg per hour for 6 hours after procedure. For patients weighing more than 110 kg, the
             initial fluid bolus and drip should be limited to those doses administered to a patient
             weighing 110 kg.)
       7.   Patients are treated with aspirin - 325 mg/day; and clopidogrel (Plavix) - 75 mg twice a day
             for at least 5 days before the procedure; or in an emergent situation give 600 mg orally of
             clopidogrel (Plavix) as a loading dose.
       8.   Prior to starting the procedure, give the patient 0.2 mg glycopyrrolate (Robinul). This seems
             to decrease the adverse effects of the carotid bulb angioplasty. You may still use atropine if
             needed.
      9.   One inch of topical 2% nitroglycerin paste (Nitropaste) may be applied to reduce the
             likelihood of mechanically induced arterial vasospasm.
     10.    Procedure is performed under conscious sedation, or without sedation.
     11.    Pedal pulses are examined with Doppler ultrasound if not palpable and marked.

     12.    A Foley catheter is placed in all patients.
     13.    Cardiac pacing leads are placed prior to sterile draping. Make sure the leads are not in any
             of the necessary fluoroscopic fields.
  14.       External cardiac pacemaker should be in the room and readily available with appropriate
             assistance from knowledgeable personnel.
  15.       Neurological status, electrocardiograms, heart rate, and blood pressure are monitored
             throughout the procedure.
  16.       Use a micropuncture system and place a sheath in the common femoral artery. This is a
             good time to obtain a baseline-activated clotting time. This is done to make certain the ACT
             device is operational and trained personnel are available.




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  17. Diagnostic angiography of both carotid arteries in a minimum of two planes, including
            anteroposterior and lateral. Intracranial circulation should be evaluated. An arch aortogram
            provides extremely valuable information necessary to perform a carotid stent procedure.
  18.      After adequate diagnostic exams are performed and the anatomy is amenable to stenting,
            the patient receives an IV loading dose of heparin 70-100 units per kilogram of body
            weight. Alternatively, the patient may be bolused with 5,000 – 6,000 units of heparin and
            then adjusted as per activated clotting times. Activated clotting time should be 2 to 2.5
            baseline, or 250 to 300 seconds. (If the arch anatomy is significantly challenging, one may
            choose to give a pre-angiographic dose of 2,000 units of heparin.
  19.      This is followed by continuous infusion of heparin at 15- to 20-units per kilogram per hour,
            or hourly boluses of 2,000 units of heparin and monitoring of activated clotting time.
  20.      Alternatively, the patient may be anticoagulated with IV bivalirudin bolus (0.75 mg/kg,
            Angiomax, followed by an infusion rate of 2.5 mg/kg/hr.
  21.      The currently approved carotid stents are found in Table 2.

  22. Following the diagnostic angiograms, the ipsilateral external carotid artery is carefully
            catheterized, generally using a 4-F diagnostic catheter, and the catheter is placed safely in
            the external carotid system.
  
  23.      A long exchange guidewire is placed in the ipsilateral external carotid artery (Amplatz
            Super Stiff .035 X 300 cm, Boston Scientific). The guiding sheath is then advanced into the
            distal common carotid using the coaxial system. (6-F Shuttle, Cook Medical) The sheath is
            then connected to pressurized saline and a heparin flush of 1 unit of heparin per mL normal
            saline at 300 mL per hour via a large bore Touhy-Borst is started. Use a mechanical pump.
            Alternatively, guiding catheters may be used rather than the Shuttle sheath.
  24.      Patient selection and aortic arch type are the most important considerations for successful
            carotid stenting. Be wary of the Type II and Type III arches and the bovine arch when
            dealing with the left carotid. The guiding catheter or Shuttle sheath will have a tendency to
            buckle in the arch. This could be disastrous, pulling down the protection device in the
            process. It is essential to keep the arch and the tip of the guiding sheath in the visual field
            for all exchanges.
  25.      Alternatively, if the aortic arch anatomy is suitable, one may use the Slip-Cath technology
            offered by Cook Medical with their Shuttle Select system and Slip-Cath technology. The
            Shuttle Select guiding sheath may be utilized with the following Slip-Cath 6.5 catheter
            configurations: the JB1, the VTK, the H1, and the SIM2. The procedure is performed by
            placing the selected Slip-Cath 6.5 French, 125-cm catheter selectively into the common
            carotid artery. Then, under direct visualization, advance the shuttle introducer sheath until it
            is at the desired position below the carotid bifurcation. This eliminates the need for the long
            stiff-exchange wire and system described above. However, it should be noted that both
            systems work. In suitable anatomy, this system works extremely well.
  26.      With the shuttle in the appropriate position in the common carotid artery, the Slip-Cath
            select catheter is carefully removed. The shuttle guiding sheath is then carefully aspirated
            and connected to a pressurized saline heparin flush via the large bore Touhy-Borst valve
            provided with the shuttle system. This is best handled with a mechanical pump. A rate of
            300 mL per hour has been satisfactory.
  27.      Before starting the heparin flush, completely purge the above system so it is free of any air
            bubbles, including flushing out the catheter port of the Touhy-Borst so it is free of blood, as
            well as air. The guiding catheter is aspirated before turning on the heparin flush.




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  28. The guiding catheter should be positioned just below the carotid bifurcation, allowing
            sufficient room for stent deployment into the common carotid artery. If the lesion is located
            higher in the cervical internal carotid, the tip of the sheath may be near the carotid
            bifurcation.
  29.      The guiding sheath in the carotid artery may be used as a reference for precise measurement
            of the internal and common carotid artery. One may also tape a quarter on the patient’s skin
            near the mandibular condyle and use this as a measurement. A quarter has a 25-mm
            diameter.
  30.      Generally, the internal carotid and area of stenosis is traversed in the lateral or lateral
            oblique under direct visualization. One may use road map or fluoro fade to accomplish this.
            The area of pathology is traversed with the selected embolic protection system. The
            approved systems are listed in Table 2. All of these systems work well. They do have some
            nuances that are peculiar to each device. All of the manufacturers have trained personnel to
            assist you in a number of your early cases.
  31.      The carotid protection device should be sized appropriately so that it makes contact with the
            wall of the internal carotid artery. These protection devices come in a variety of sizes. See
            Table 1.
  32.      The carotid protection device should be positioned in a relatively straight portion of the
            cervical internal carotid artery, at least 1 cm above the superior margin of the stent
            deployment.
  33.      If the minimal diameter of the area of vessel pathology is 2 mm or less, it is dilated with a
            3- to 3.5-mm monorail angioplasty balloon.
  34.      At this point in the procedure you should have a carotid protection device in place in the
            cervical portion of the internal carotid. Occasionally, in extreme tortuosity this will not be
            the ideal location. The system you are now working with is a monorail system and all
            subsequent balloons and stents need to be of the monorail type.
  
  35.      Carotid stenting and use of the appropriate guidewire and catheters requires meticulous
            technique. Always wipe the guidewire clean with moist saline and keep it moist when
            advancing the stent, angioplasty balloon, or retrieval device.
  36.      Before balloon inflation, have available 0.6 to 1 mg of atropine that can be given quickly, if
            needed. Many will give the atropine before balloon angioplasty in virtually all cases.
  
  37.      Frequently accompanying the symptomatic bradycardia that occurs following stenting or
            balloon angioplasty of the carotid bifurcation, patients will experience hypotension. One
            should be prepared to treat with increasing fluids, as well as administration of Dopamine if
            necessary. In our experience, it has been important to have a Dopamine drip available and
            ready to use expeditiously. For adults: 5 to 20 µg/kg per minute as a continuous IV
            infusion. It should be noted that these patients are often very fragile cardiac-wise.
            Dopamine should be used with great caution since the patients are prone to arrhythmias.
  38.      Balloon inflation should not exceed 30 seconds. The balloon should be inflated and deflated
            relatively slowly.
  39.      In addition to road mapping or fluoro fade, bony landmarks should be identified that
            delineate the desired stent position. These landmarks, including the area of the stenting,
            may be marked on the monitor screen.
  40.      When the stent is satisfactorily positioned, deployment of the self-expanding stent is
            accomplished by retracting the outer sleeve. (Note: the peculiar properties of any of the
            approved stents should be clearly understood by the operator before attempting deployment
            in the carotid system.)



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  41. After stent deployment, the delivery catheter is carefully withdrawn under fluoroscopy
            control making certain that the stent is not caught or moved by the delivery device.
  42.      Post-deployment angioplasty is performed by using a high-pressure monorail
            semicompliant balloon. Balloon size is tailored to the smallest diameter of the stent.
            Although it is not mandatory to postdilate all stents, in our experience this has generally
            been necessary.
  43.      We try to keep the inflation of the angioplasty balloon within the confines of the stent. We
            routinely underdilate. Our maximum for the internal carotid artery seldom exceeds 5 mm.
            This has dramatically reduced problems of hypotension and bradycardia.
  44.      There should be sufficient pause between inflations to allow restoration of cerebral
            profusion. One should also make certain the patient is hemodynamically stable before
            additional inflations are performed. (It is rare to perform more than a single inflation.)
  45.      Residual ulceration external to the stent is usually of no clinical importance.

  46. Iatrogenic vasospasm usually resolves shortly after removal of the guidewire from the
            internal carotid.
  47.      You may consider the injection of Nimodipine (200 micrograms diluted in a 10 mL solution
            injected slowly as a 2- to 3-mL bolus), or nitroglycerin 100 to 150 µg into the carotid artery
            to treat mechanically induced vasospasm.
  48.      You are now ready to remove the carotid protection device. Manufacturer’s directions
            should be followed explicitly. The device should be recaptured under direct visualization.
            Special note: It is possible for the capturing catheter to engage the proximal edge of the
            stent. Generally, this problem can be eliminated if the physician puts a very slight bend in
            the distal portion of the retrieval catheter. It is important to make sure that the distal part of
            the stent is in a vertical (nonangled) portion of the common carotid artery. If it is not, you
            may have to add an additional stent to create this vertical position to allow the retrieval
            catheter to pass the edge of the carotid stent. If you have difficulty advancing the retrieval
            catheter through a portion of the stent, turning the patient’s head (generally to the
            contralateral side) will facilitate passage.
  49.      Recalcitrant iatrogenic vasospasm usually responds well to low-pressure balloon
            angioplasty (<3 atmospheres).
  50.      Anteroposterior and lateral cerebral angiograms should be obtained after stent placement in
            all cases to exclude embolic branch occlusion and to document new patterns of flow. It is
            important to compare these postangiograms with the preangiograms while the patient is still
            on the table.
  51.      Sheath removal and closure device placement providing the angiogram is normal and the
            patient is neurologically intact. Alternatively, the femoral sheath may be removed when the
            activated clotting time is <150.
  52.      If there is any question about possibly needing to go back to do a repeat cerebral
            angiography, leave the sheath in the groin and send the patient to the ICU. The sheath may
            be removed the next morning.
  53.      Postprocedure neurological evaluation is carefully performed.
  54. Before stent deployment, the mean arterial blood pressure should be maintained at or above
            baseline. However, following successful revascularization, the mean arterial pressure may
            be lowered 10% to 20% below baseline to prevent cerebral reperfusion injury. In a patient
            with a high-grade carotid artery stenosis, it is desirable that the patient remains somewhat
            hypotensive after restoration of flow. We have found that any systolic >80 is generally
            adequate. Mean pressures should not exceed about 55 to 60.


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  55. The effect of heparin is allowed to taper physiologically, rather than being reversed with
            protamine.
  56.      The patient is monitored in the intensive care unit for 12- to 24-hours after treatment. Some
            patients may need further monitoring until they become hemodynamically stable.
  57.      Plavix 75 mg/day is continued for 3 months, and aspirin 325 mg/day is continued
            indefinitely.
  58.      Patient is advised to avoid neck manipulation or deep massage for at least 6 months.
  
  59. A follow-up ultrasound of the neck is performed at 1, 6, and 12 months to document
            continued patency. Most restenosis occurs within the first six months. Ultrasounds are then
            obtained on a yearly basis. It is essential to follow these patients long term.




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STENT SIZING
  1.       The stent margin should extend 1 cm beyond the proximal and distal margins of the stenotic
            plaque or dissection.

  2.       Prominent carotid artery curves or kinks should be taken into account when determining the
            appropriate stent length.

  3.       Do not position the stent margins within an acute bend or kink in the carotid artery.

  4.       The stent diameter should be 1- to 2-mm larger than the largest vessel diameter the stent
            will need to oppose.

  5.       Stent oversizing leads to greater metallic coverage of the lesion per unit area. Theoretically,
            decreasing distal emboli and decreasing tissue prolapse.

  6.       If more than one stent is used, 20% stent overlap is desirable.

  7.       Stent circumference: the second stent diameter should be greater than the in situ stent
            diameter to which it is to contact.

  8.       Each of the stents has some nuances peculiar to that stent. However, virtually all of them
            deploy without significant foreshortening. Precision in placement is essential. It is generally
            not hard to be very precise in positioning the carotid stents.




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