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Guglielmi Detachable Coils: an alternative therapy for high-risk aneurysms.

Introduction

The Guglielmi Detachable Coil (GDC) system offers a new modality of treatment for patients who would otherwise be relegated to medical management. The GDC system was developed by Guido Guglielmi, MD, a professor of radiology at UCLA, in collaboration with Target Therapeutics, Inc. Clinical trials of the GDC system were supervised under the Food and Drug Administration (FDA).

Investigational Device Exemption (IDE) was initiated in January 1991. Since then, more than 1200 patients have been treated in the United States and an additional 4000 patients worldwide. In September 1995, the GDC system received FDA approval for treatment of surgically high-risk aneurysms. Aneurysms are usually classified as being surgically high-risk if the patient is elderly or in poor medical condition. Patients who present with a high Hunt & Hess grade (grade III or higher) and patients who have aneurysms in the posterior circulation (ie, basilar tip) are also considered a high risk for surgical intervention. In this article, the coiling procedure is discussed. Goals of treatment, as well as risks and benefits associated with GDC, are incorporated. Nursing care before, during and after the GDC placement are addressed.

Procedure

The GDC coil is a soft, platinum alloy microcoil mounted on a stainless steel delivery wire (Fig 1). The softness of the platinum allows the coil to conform to the individual shape of a patient's aneurysm. The coils are available in various helical diameters and lengths, which allow the interventionalist to achieve optimal occlusion.

[Figure 1 ILLUSTRATION OMITTED]

In order to detach the coils, the aneurysm must be accessible. Similar to a cerebral arteriogram, using the femoral artery and fluoroscopic imaging, a microcatheter is navigated through the aorta, around the aortic arch and then into the vessel specific to the aneurysm. Once the microcatheter is in position, the GDC system is advanced through the microcatheter and into the aneurysm sac. The coil is then positioned in the aneurysm. If satisfactory placement of the coil is obtained, a low-voltage current is applied to the guidewire on which the coil is mounted. The current causes the coil to detach from the guidewire. The guidewire is then withdrawn. After the GDC coil is successfully in place, it occludes the aneurysm, isolating it from normal circulation. The number of coils required to achieve occlusion is patient-specific. Some aneurysms may require only a single coil, while giant aneurysms may require as many as 20. The average number of coils is five. Once the aneurysm is occluded, the pressure within the aneurysm is reduced, and ultimately, the hemorrhage or rehemorrhage risk is decreased.

Benefit

Because the GDC technique is minimally invasive, as compared to an open craniotomy, the recovery time may be shorter. The average length of stay for patients with an unruptured aneurysm treated with GDCs is 5 days at our institution. For an unruptured aneurysm that is treated with surgical clipping, the average length of stay is 7 days.

Risks

As with any medical treatment there are risks. Because the coils are thrombogenic, one of the major risks is stroke. Stroke can occur because the parent artery feeding the aneurysm may become occluded. A stroke can also occur from introduction of air or particles into the catheter system. In order to decrease the stroke risk, continuous flush systems are utilized during the procedure to minimize blood stagnation within the catheter. The flush solution used is 1000 cc of normal saline solution with 4000 units of heparin sodium added. Other risks include perforation or rupture of the aneurysm, vasospasm, damage to the femoral artery or to the parent artery, infection, contrast reaction and death due to rupture of the aneurysm or cerebral infarct.

At our institution, general anesthesia is used for patients undergoing GDC procedures. General anesthesia limits patient movement during the procedure, reducing the time necessary to catheterize the aneurysm. The more time that elapses while attempting to catheterize the vessel, the greater the chance of occluding flow, creating thrombus and causing a stroke. Thus, additional risks are those associated with general anesthesia.

Contraindications

Patients who are considered poor candidates for the GDC procedure include those who are found to have an intracerebral hematoma because they are not able to be anticoagulated. Patients whose aneurysm is found to have a broad neck are also considered poor candidates for GDC because the coils would be more prone to migration into the parent vessel.

Preoperative Care

Preoperative nursing care is influenced by the circumstances of admission. If the patient has had a subarachnoid hemorrhage (SAH), the situation is going to be emergent and most of the preoperative teaching is geared toward the family. Preoperative teaching for the patient is dependent on his or her cognitive abilities. A teaching tool has been developed and is completed by the neurosurgical intensive care nurses. It is important to provide information about pre-, intra- and postoperative care. Appropriate nursing diagnoses include knowledge deficit, fear and anxiety. Efforts should be made to provide a supportive environment that will facilitate coping mechanisms for the patient and family to deal with this crisis.

Diagnostic procedures performed prior to the coiling procedure include chemistry and hematology profiles, with attention to blood urea nitrogen (BUN) and creatinine as indicators of renal function, and a protime (PT), partial thromboplastin time (PTT) and a platelet count as indicators of coagulation properties. The patient usually has had a computed tomography (CT) scan to diagnose the SAH. The patient will need an electrocardiogram (ECG) if over 50 years of age in preparation for general anesthesia. At our institution, patients are typed and cross-matched for 2 units of packed red blood cells in case the aneurysm hemorrhages or is perforated during the procedure. It is also important to note if the patient has a history of an allergy to iodine because the contrast used for the procedure is an iodine-based solution.

Depending on the stability of the patient, the GDC procedure may or may not be done on the day of the SAH or the same day as the angiogram. All efforts are made to treat the ruptured aneurysm as soon as possible because the risk of a rehemorrhage is present. Patients who present with an unruptured aneurysm are scheduled on an elective basis unless they are symptomatic. On the day of the procedure, the patient is kept NPO, a baseline neuro exam and vital signs are documented, an operating room checklist is completed and the family is allowed to visit.

Intraprocedural Nursing Care

The interventional neuroradiology team at our institution is comprised of the following personnel:

1) neuro-interventionalist/neurosurgeon

2) anesthesiologist and nurse anesthetist

3) interventional neuroradiology nurse

4) interventional neuroradiology technologist

5) neurophysiology technologist

Electroencephalogram (EEG) monitoring is always used, but it may also include brainstem auditory evoked responses (BAERs) and somatosensory evoked potentials (SSEPs) as indicators of brainstem function if the aneurysm is in the posterior circulation. The team meets the patient on arrival to the interventional neuroradiology suite.

Once the patient arrives in the interventional suite, monitoring equipment is secured, including ECG, pulse oximetry and noninvasive blood pressure. The medical record is reviewed for completed consent forms and a completed preoperative checklist. The anesthesiologist assesses adequacy of intravenous (IV) access. When satisfactory IV access is obtained, induction of anesthesia is begun. After the patient is intubated, the interventional team simultaneously prepares the patient for the coiling procedure. A urinary catheter is inserted, if not already present, and an arterial line is placed. Once the arterial line is secured, a baseline activated clotting time (ACT) is then obtained by the interventional nurse. The normal range for an ACT is 91-150 seconds. If the patient presented with SAH, a triple lumen or pulmonary artery catheter is inserted for additional intravenous access and monitoring. The neurophysiology technician applies the necessary electrodes. Once all of the ancillary personnel have their monitoring lines established, the patient is prepped and draped by the radiology technologist. As long as the patient has no history of an allergy to iodine, both groins will be shaved and prepped with a povidoneiodine 10% solution prior to application of the sterile drape. After the patient is draped, the femoral artery is accessed and a sheath is inserted. The neuro-interventionalist begins catheterizing the cerebrovascular circulation. At this point, the interventional nurse is responsible for assuring that the continuous flush system is irrigating the catheter that is being advanced into the cerebral circulation. Once the neuro-interventionalist acquires a digital acquisition of the aneurysm, the aneurysm is measured and appropriate sized coils selected. The first coil is then guided into the aneurysm. When satisfactory placement of the coil is achieved, the coil is detached by the low-voltage current. Coils continue to be placed in the same manner until satisfactory occlusion of the aneurysm is demonstrated. (Fig 2). This is considered a high-risk aneurysm to treat surgically because of its location, regardless of the patient's neurological grade or medical condition. In the post-treatment image, occlusion of the aneurysm is seen, as well as filling of all the normal vasculature.

[Figure 2 ILLUSTRATION OMITTED]

The neuro-interventionalist may request that the patient be anticoagulated once the dome of the aneurysm is protected from rupture. This may minimize the risk of thrombus formation at the coil site or parent vessel. A bolus of heparin 2500-4000 units is administered intravenously by the anesthesiologist. An ACT is checked by the interventional nurse 5 minutes after the administration of heparin; values should be 1.5-2.0 times the patient's baseline.

The neuro-interventionalist again performs digital acquisition of the aneurysm post-coiling. If the aneurysm is satisfactorily occluded, the anesthesiologist begins reversal of anesthesia. While anesthesia is being reversed, the sterile field is maintained in the event that the patient wakes up with an unanticipated neurologic deficit, which requires additional intervention. Because one of the risks is thrombus formation in the parent artery of the aneurysm, urokinase is kept on hand in the event that lytic therapy is indicated. At our institution, an operating room and surgical team is also on standby in the event that the aneurysm ruptures, an artery is damaged or GDC occlusion is not possible. If there are no changes from the patient's baseline status, the patient is transported directly to the neurointensive care unit (NICU) and procedure results are shared with the family.

Postprocedural Nursing Cue

Prior to patient transport to the NICU, the interventional nurse calls a detailed report to the nurse who is receiving the patient. If the patient has not had a subarachnoid hemorrhage, or if the patient came directly to the interventional neuroradiology suite from another institution, the patient may not have originated from the NICU. It may be necessary to include a medical history and preoperative patient assessment. An overview of the procedure is given, including the number of coils placed, percentage of occlusion of the aneurysm, current neurological status, the site and size of the femoral sheath, circulatory assessment of the extremity specific to the sheath site, current medications, location of all invasive lines and whether or not the patient will arrive intubated. These patients bypass the recovery room and recover in the NICU.

Medical management of the patient includes hourly monitoring of neurological assessment and vital signs. Any focal deficits need to be reported to the physician immediately. Prudent blood pressure monitoring is essential. The mean arterial pressure (MAP) in most patients will be kept between 70-80 mm Hg. It may be necessary to use vasopressors or antihypertensives for some patients who are unable to be maintained in this range. At our institution, the patient is anticoagulated for at least the first 24 hours with a heparin infusion. Protime (PT) and partial thromboplastin time (PTI) are obtained every 4 hours while the heparin infusion is maintained. Routinely, these patients receive antiepileptic drugs and steroids. If the patient presented with SAH, he or she will also be on nimodipine; volume expanders, such as albumin, are likely to be used prophylactically for cerebral vasospasm. Transcranial Doppler studies are performed daily for evidence of vasospasm and correlated with the patient's neurologic exam. Diuretics may be given for cerebral edema or fluid overload. Codeine is the most common medication given for headaches as needed. Appropriate nursing diagnoses are in Table 1.
Table 1. Nursing Diagnoses

Nursing Diagnoses Outcome

Potential for hemorrhage Integrity is maintained at
 sheath site.

Potential for Adequate peripheral circulation of
circulatory compromise affected extremity is maintained.

Potential for Adequate renal function post
renal compromise procedure is maintained as
 evidenced by urine output of
 30 ml/hr. (The contrast used
 is nephrotoxic.)

Potential for Patient will be neurologically
neurological compromise stable.

Potential for alteration Patient will maintain cerebral
in cerebral tissue tissue perfusion as evidenced
perfusion by stable ICP and CBF

Potential for altered Airway will be maintained with
respiratory status stable oxygen and carbon dioxide.

Potential for injury Will be free of harm.

Fluid volume deficit or Fluid volume will be maintained
excess due to cerebral and electrolytes will be within
edema, volume expansion normal limits.
and diuretics

Pain Will be comfortable.

Nursing Diagnoses Intervention

Potential for hemorrhage 1. Assess site hourly for bleeding
 or hematoma.
 2. Instruct patient and/or family
 that extremity with sheath must
 be kept straight and bed rest
 maintained.
 3. Avoid hip flexion.
 4. Keep head of bed elevated
 30[degrees].
 5. Maintain a pressure setup with
 a 500 cc normal saline solution,
 with 1000 units of heparin
 to a transducer to the side
 port of the sheath. (The sheath
 is maintained until coagulation
 profile returns to normal and
 the physician feels that no
 further endovascular
 intervention is necessary)

Potential for 1. Perform neurovascular checks
circulatory compromise hourly; assess color,
 temperature and pulses,
 as well as for any pain
 or paresthesia.
 2. Monitor pulse oximetry
 to great toe of affected
 leg.

Potential for 1. Maintain strict intake
renal compromise and output.
 2. Monitor BUN and creatinine.
 3. Maintain intravenous
 fluids as ordered.

Potential for 1. Perform hourly neurologic exams.
neurological compromise 2. Report changes in level of
 consciousness or focal deficits
 to physician.
 3. Maintain and monitor invasive
 lines (arterial line, central
 venous or pulmonary catheter and
 possibly ventriculostomy).

Potential for alteration 1. Maintain ventriculostomy
in cerebral tissue perfusion.
perfusion 2. Notify physician of an
 increase in ICP of 5
 mm Hg or an ICP greater
 than 20 mm Hg.
 3. In patients without ICP
 monitoring, assess for
 complaints of headache and
 decreased level of
 consciousness.

Potential for altered 1. Monitor continuous
respiratory status pulse oximetry.
 2. Assess rate and quality
 of respirations.
 3. Maintain oxygen as ordered.
 4. Maintain endotracheal
 tube if intubated.
 5. Maintain ventilator setting
 if mechanical ventilation
 is necessary.

Potential for injury 1. Perform a fall-risk assessment
 on admission and with any
 change in level of
 consciousness.
 2. Obtain a physician's order for
 restraints when needed.
 3. Maintain bed in low position.
 4. Keep all siderails up.

Fluid volume deficit or 1. Monitor electrolytes and
excess due to cerebral report abrnormal values.
edema, volume expansion 2. Monitor intake and output.
and diuretics 3. Maintain intravenous fluids.

Pain 1. Assess patient for signs/
 symptoms of discomfort such as
 restlessness, elevated blood
 pressure or grimacing.
 2. Medicate with analgesics as
 ordered prn.




Discharge Planning and Follow-up Care

Written discharge instructions are patient-specific and depend on the SAH grade at the time of admission and current status. Patients that are grades 0-II are usually instructed not to lift anything heavier than a knife, fork or newspaper for 3 weeks. The patients receive a telephone call from a nurse within 1 week after discharge to review medications and assess the patients' progress. All of our GDC patients are sent home on phenytoin (Dilantin) 300 mg PO daily prophylactically for seizures. This may be weaned once a normal electroencephalogram is obtained. Oral ranitidine (Zantac) 150 mg twice daily is ordered prophylactically for stomach ulcers, while the patient remains on dexamethasone. A 2-3 week dexamethasone taper is prescribed to avoid abrupt steroid withdrawal and cerebral edema.

A follow-up angiogram is performed 1 month after the coiling procedure to assess patency of the parent artery and evaluate for coil compaction. Coil compaction is usually seen in patients who did not have complete occlusion of their aneurysm. If the 1-month follow-up is satisfactory, the patients are then followed with angiography at 6-month intervals. On the 6month follow-up, 2 patients have had coil compaction that required placement of additional coils. If the aneurysm has not ruptured and was not technically difficult to coil, the patient may be followed by an MRI/MRA at 6 months and then an angiogram at 1 year. The patient is seen in the neurosurgeon's office approximately 3 weeks after their procedure. At that time, decisions are made about increasing the patient's activity, return to work and ability to drive. Most patients are encouraged to return to the lifestyle to which they were accustomed. Patients with neurological deficits are assessed for their need to continue rehabilitation (speech therapy, occupational therapy, physical therapy and skilled

At our institution, our interventionalist is also a neurosurgeon, which permits him to function in a dual role. This optimizes continuity of care.

Summary

The Guglielmi Detachable Coils (GDCs) offer another avenue of treatment to patients who in the past would have received more conservative treatment because of aneurysm location, poor medical condition or neurological grade. At present, the GDC system is in its infancy and is only approved for aneurysms that are considered to be high-risk for an open craniotomy and clipping. As the GDC technology continues to develop and the procedure becomes more refined, our interventionalist feels it could begin to replace surgical clipping as the treatment of choice for some aneurysms. Ongoing issues need to be addressed. Our long-term follow-up is limited because the first patient to undergo a GDC procedure was treated in 1991.

Reimbursement for the coils can be a problem. Many insurance companies only reimburse for 1 coil, even though multiple coils may be used. Nurses may be instrumental in educating third-party payers about the procedure to improve reimbursement. Overall, the GDC system promises to be an influential tool in the treatment of intracranial aneurysms and provides hope for patients not suited for surgical intervention.

Acknowledgment

The author wishes to thank Professor Robert H. Rosenwasser, MD, chief of interventional neuroradiology and cerebrovascular neurosurgery, Thomas Jefferson University and Wills Eye Hospital; Patricia Gannon, RN, clinical coordinator of cerebrovascular neurosurgery, Thomas Jefferson University Hospital; and my husband for their contributions and support for this manuscript.

References

[1.] Coleman R, Sifri-Steele C: Treatment of posterior circulation aneurysms using platinum coils. J Neurosci Nurs 1994; 26:367-370.

[2.] Guglielmi G, Vinuela F, Sepetka I, Macellari V: Electrothrombosis of saccular aneurysms via endovascular approach. Part 1: Electrochemical basis, technique, and experimental results. J Neurosurg 1991; 75:1-7.

[3.] Jallo J, Rosenwasser R: Endovascular neurosurgery. Contemp Neurosurg 1995; 17(2):1-6.

[4.] Rinne J, Heresniemi J, Puranen M et al: Multiple aneurysms in a defined population: Prospective angiographic and clinical study. J Neurosurg 1994; 35(5):803-808.

[5.] Teitelbaum G, Higashida R, Halbach V et al: Flow-directed use of electrolytically detachable platinum embolization coils. J Vasc Interventional Radiol 1994; 5:453-456.

[6.] Zubillage AF, Guglielmi G, Vinuela F, et al: Endovascular occlusion of intracranial aneurysms with electrically detachable coils: Correlation of aneurysm neck size and treatment results. AJNR 1994; 15:815-820.

Questions or comments about this article may be directed to: Suzanne R Morrison, RN, BSN, Interventional Neuroradiology, Wills Eye Hospital, 900 Walnut Street, Philadelphia, Pennsylvania, 19107. She is a clinical coordinator.

Copyright [C] American Association of Neuroscience Nurses 0047-2603/97/2904/0232$1.25
COPYRIGHT 1997 American Association of Neuroscience Nurses
No portion of this article can be reproduced without the express written permission from the copyright holder.
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Author:Morrison, Suzanne R.
Publication:Journal of Neuroscience Nursing
Date:Aug 1, 1997
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