1. Carotid Endarterectomy and Stenting Mani K.C Vindhya M.D Asst Prof of Anesthesiology Nova Southeastern University

2. Introduction -- Stroke and Transient Ischemic Attacks (TIA's) Introduction -- Stroke and Transient Ischemic Attacks (TIA's) Stroke statistics (Heart and Stroke Facts: 1997 Statistical Suppl. Dallas, TX: American Heart Association) Stroke statistics (Heart and Stroke Facts: 1997 Statistical Suppl. Dallas, TX: American Heart Association) Stroke = third leading cause of death in U.S. Stroke = third leading cause of death in U.S. (after heart disease and cancer) (after heart disease and cancer) Over 500,000 new cases in U.S. each year (75% in carotid distribution) Over 500,000 new cases in U.S. each year (75% in carotid distribution) Mortality: nearly 1/4 die Mortality: nearly 1/4 die Morbidity: often significant and permanent disability Morbidity: often significant and permanent disability

3. Types and causes of stroke: (Cummings RO (ed). ACLS. American Heart Association, 1997, pp. 10-1--10-20.) Ischemic strokes (75%) – Ischemic strokes (75%) – due to occlusion of a blood vessel to the brain due to occlusion of a blood vessel to the brain Anterior circulation strokes Anterior circulation strokes = carotid territory strokes = carotid territory strokes usually involve the cerebral hemispheres usually involve the cerebral hemispheres Posterior circulation strokes Posterior circulation strokes = vertebrobasilar territory strokes = vertebrobasilar territory strokes usually affect brain stem or cerebellum usually affect brain stem or cerebellum Hemorrhagic strokes (25%) Hemorrhagic strokes (25%) Subarachnoid hemorrhage (SAH) Subarachnoid hemorrhage (SAH) = bleeding onto surface of brain = bleeding onto surface of brain Aneurysm = most common cause Aneurysm = most common cause Intracerebral hemorrhage Intracerebral hemorrhage = bleeding into brain parenchyma = bleeding into brain parenchyma Hypertension = most common cause Hypertension = most common cause

4. Treatment of Stroke – now includes thrombolytic therapy Treatment of Stroke – now includes thrombolytic therapy Thrombolytic agent = rt-PA Thrombolytic agent = rt-PA I.V. thrombolytic therapy is best initiated within 3 hours after onset of stroke symptoms. I.V. thrombolytic therapy is best initiated within 3 hours after onset of stroke symptoms.

5. ACLS Algorithm for Suspected Stroke Patients

6. Detection Detection Hallmark of stroke = sudden onset of focal brain dysfunction Hallmark of stroke = sudden onset of focal brain dysfunction Early recognition of “brain attack” signs and symptoms Early recognition of “brain attack” signs and symptoms Carotid (anterior) circulation Carotid (anterior) circulation ! unilateral paralysis! visual disturbance ! unilateral paralysis! visual disturbance ! numbness! monocular blindness ! numbness! monocular blindness language disturbance language disturbance Vertebrobasilar (posterior) circulation Vertebrobasilar (posterior) circulation ! vertigo! numbness ! vertigo! numbness ! visual disturbance! dysarthria ! visual disturbance! dysarthria ! diplopia! Ataxia ! paralysis ! diplopia! Ataxia ! paralysis

7. Dispatch – early activation of EMS Dispatch – early activation of EMS Delivery – prehospital transport and management Delivery – prehospital transport and management Minimize time in the field Minimize time in the field Door Door Immediate general assessment: <10 min from arrival Immediate general assessment: <10 min from arrival Immediate neurologic assessment: <25 min from arrival (often includes Glasgow Coma Scale and Hunt-Hess classification) Immediate neurologic assessment: <25 min from arrival (often includes Glasgow Coma Scale and Hunt-Hess classification)

9. Data – Does the CT scan show intracerebral or subarachnoid hemorrhage? Data – Does the CT scan show intracerebral or subarachnoid hemorrhage? If yes, consult neurosurgery. If yes, consult neurosurgery. If no, then probable ischemic stroke. If no, then probable ischemic stroke. Review CT exclusions: are any oberved? Review CT exclusions: are any oberved? Repeat neurologic exam: are deficits variable or rapidly improving? Repeat neurologic exam: are deficits variable or rapidly improving? Review thrombolytic exclusions: are any observed? Review thrombolytic exclusions: are any observed? Review patient data: is symptom onset now >3 hours? Review patient data: is symptom onset now >3 hours? Decision – Is the patient a candidate for thrombolytic therapy? Decision – Is the patient a candidate for thrombolytic therapy? Drug – Begin thrombolytic therapy with i.v. rt-PA Drug – Begin thrombolytic therapy with i.v. rt-PA

10. Transient Ischemic Attack (TIA) Transient Ischemic Attack (TIA) TIA = a reversible episode of focal brain dysfunction TIA = a reversible episode of focal brain dysfunction Initial signs and symptoms of stroke Initial signs and symptoms of stroke Lasts only a few minutes to hours before resolving Lasts only a few minutes to hours before resolving TIA = the most important forecaster of brain infarction TIA = the most important forecaster of brain infarction 5% will develop cerebral infarction within 1st month. 5% will develop cerebral infarction within 1st month. Risk = 12% at one year, and an additional 5% for each year after that Risk = 12% at one year, and an additional 5% for each year after that Treatments for TIA: Treatments for TIA: Carotid endarterectomy, angioplasty & stenting – if severe Carotid endarterectomy, angioplasty & stenting – if severe (>70% narrowing) of internal carotid artery (>70% narrowing) of internal carotid artery Aspirin or ticlopamide Aspirin or ticlopamide Oral anticoagulants – to prevent embolism to brain in patients with cardiac causes of stroke, especially atrial fibrillation Oral anticoagulants – to prevent embolism to brain in patients with cardiac causes of stroke, especially atrial fibrillation

11. History of Carotid Endarterectomy (CEA) Surgery History of Carotid Endarterectomy (CEA) Surgery Early history (Koller RL. Postgrad Med 90: 81-86, 1991.) Early history (Koller RL. Postgrad Med 90: 81-86, 1991.) 1950's: CEA first used to treat cerebrovascular disease 1950's: CEA first used to treat cerebrovascular disease 1971: 15,000 operations per year in U.S. 1971: 15,000 operations per year in U.S. Mid-1980's: > 100,000 operations per year Mid-1980's: > 100,000 operations per year 1984: CEA = 3rd most commonly performed operation in U.S. 1984: CEA = 3rd most commonly performed operation in U.S. Late 1980's: The appropriateness of CEA surgery was questioned. Late 1980's: The appropriateness of CEA surgery was questioned. "Only two prospective randomized trials had been carried out, neither of which demonstrated clear benefit." "Only two prospective randomized trials had been carried out, neither of which demonstrated clear benefit." In the patient with TIA's, which is better? In the patient with TIA's, which is better? medical management, surgery, or both? medical management, surgery, or both? CEA: Perioperative mortality and morbidity = 10% in one large study CEA: Perioperative mortality and morbidity = 10% in one large study (Winslow CM et al. N Engl J Med 318: 721-7, 1988). (Winslow CM et al. N Engl J Med 318: 721-7, 1988). C. Early 1990's: C. Early 1990's: Symptomatic carotid stenosis Symptomatic carotid stenosis a. 3 clinical trials showed benefit of CEA (Easton JD, Wilterdink JL. a. 3 clinical trials showed benefit of CEA (Easton JD, Wilterdink JL. Ann Neurol 35: 5-17, 1994). Ann Neurol 35: 5-17, 1994). NASCET (N Engl J Med 325: 445-53, 1991) NASCET (N Engl J Med 325: 445-53, 1991) ECST (Lancet 337: 1235-43, 1991) ECST (Lancet 337: 1235-43, 1991) VA (Mayberg MR et al, JAMA 266: 3289-94, 1991) b. For > 60- 70% stenosis, VA (Mayberg MR et al, JAMA 266: 3289-94, 1991) b. For > 60- 70% stenosis, CEA better than optimal medical care alone CEA better than optimal medical care alone

12. CEA for symptomatic carotid stenosis (70-99%) [Rothwell P et al, Lancet 261: 107-16, 2003; Brown, M. (2008) “Carotid endarterectomy, angioplasty and stenting”, in Hachinski, V. (ed.), The Diagnosis, Treatment, and Prevention of Cerebrovascular Disease: A Prioritized Approach, The Biomedical and Like Sciences Collection, Henry Stewart Talks Ltd, London (online at http://www.hstalks.com/bio)]: CEA for symptomatic carotid stenosis (70-99%) [Rothwell P et al, Lancet 261: 107-16, 2003; Brown, M. (2008) “Carotid endarterectomy, angioplasty and stenting”, in Hachinski, V. (ed.), The Diagnosis, Treatment, and Prevention of Cerebrovascular Disease: A Prioritized Approach, The Biomedical and Like Sciences Collection, Henry Stewart Talks Ltd, London (online at http://www.hstalks.com/bio)]: ! Surgical arm: 6-7% stroke or operative death ! Surgical arm: 6-7% stroke or operative death in first few months, but then M&M levels off. in first few months, but then M&M levels off. Medical arm: 25% had recurrence in 3 years, 33% recurrence in 10 years Medical arm: 25% had recurrence in 3 years, 33% recurrence in 10 years Surgical treatment was better than medical treatment Surgical treatment was better than medical treatment Surgery is highly effective in preventing recurrent events Surgery is highly effective in preventing recurrent events In patients treated medically, the highest risk for recurrence is in the first 3 years. In patients treated medically, the highest risk for recurrence is in the first 3 years. Surgery is only beneficial if performed Surgery is only beneficial if performed soon after symptoms. soon after symptoms.

13. Asymptomatic carotid stenosis Asymptomatic carotid stenosis Asymptomatic Carotid Atherosclerosis Study (ACAS) (JAMA 1421-28, 1995): Asymptomatic Carotid Atherosclerosis Study (ACAS) (JAMA 1421-28, 1995): Surgery also of value for asymptomatic stenosis (>60%). Surgery also of value for asymptomatic stenosis (>60%). 53% reduction in risk of ipsilateral stroke and any perioperative stroke or death. 53% reduction in risk of ipsilateral stroke and any perioperative stroke or death. Asymptomatic carotid bruits are common. Asymptomatic carotid bruits are common. Occur in 5% of population > age 45 Occur in 5% of population > age 45 More common in women More common in women Risk of stroke = 2% per year Risk of stroke = 2% per year ACST: Risk of Stroke or Death after CEA or Medical Treatment for Asymptomatic Carotid Stenosis (60- 99%) (Halliday A et al, Lancet 363: 1491-1502, 2004): ACST: Risk of Stroke or Death after CEA or Medical Treatment for Asymptomatic Carotid Stenosis (60- 99%) (Halliday A et al, Lancet 363: 1491-1502, 2004): Initial risk greater for surgical treatment (CEA) Initial risk greater for surgical treatment (CEA) Risk at 5 years greater for medical treatment Risk at 5 years greater for medical treatment Surgical vs. medical: Risks cross at 2 years. Surgical vs. medical: Risks cross at 2 years.

14. Carotid Angioplasty and Stenting Carotid Angioplasty and Stenting Carotid Angioplasty – Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVITAS): Comparison of Endovascular vs. Surgical Treatment Carotid Angioplasty – Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVITAS): Comparison of Endovascular vs. Surgical Treatment (McCabe DJH et al, Stroke 36: 281-6, 2005) (McCabe DJH et al, Stroke 36: 281-6, 2005) The 5-year risk of stroke or death was the same. The 5-year risk of stroke or death was the same. Cranial nerve palsies or hematomas were more common with surgery. Cranial nerve palsies or hematomas were more common with surgery. The 5-year rate of restenosis was greater with endovascular treatment. The 5-year rate of restenosis was greater with endovascular treatment.

15. . Carotid Stenting – Stenting and Angioplasty with Protection in Patients at High Risk for Endarterectomy (SAPPHIRE) (Yadav JS et al, New Engl J Med 361: 1493-1501, 2004). ! “...Carotid stenting with the use of an emboli-protection device is not inferior to carotid endarterectomy.”

16. Anesthetic Management of Carotid Angioplasty and Stenting (Drummond J. Anesthesia for Carotid Endarterectomy / Stenting. Dannemiller Anesthesiology Review Course, 2008) Anesthetic Management of Carotid Angioplasty and Stenting (Drummond J. Anesthesia for Carotid Endarterectomy / Stenting. Dannemiller Anesthesiology Review Course, 2008) Dual antiplatelet treatment (aspirin and clopidogrel) Dual antiplatelet treatment (aspirin and clopidogrel) Usually transfemoral (sometimes transcarotid) Usually transfemoral (sometimes transcarotid) Usually MAC (neurologic exam) Usually MAC (neurologic exam) Two stages: Dilatation and Stenting Two stages: Dilatation and Stenting Heparin to maintain ACT 250-300 Heparin to maintain ACT 250-300 e.g. 500 units + 1000 units/hr e.g. 500 units + 1000 units/hr Prevent / treat bardycardia Prevent / treat bardycardia independent arterial line independent arterial line glycopyrrolate pre-treatment glycopyrrolate pre-treatment atropine before dilatation (+/-) atropine before dilatation (+/-) external pacer (on and available) external pacer (on and available) Carotid stenting can cause severe bradycardia, hypotension, and Carotid stenting can cause severe bradycardia, hypotension, and cerebral hypoperfusion. cerebral hypoperfusion.

17. Preoperative Evaluation Preoperative Evaluation Typical diagnostic workup for TIA/stroke (Koller RL. Postgrad Med 90: 81-96, 1991) Typical diagnostic workup for TIA/stroke (Koller RL. Postgrad Med 90: 81-96, 1991) CT scan and/or MRI CT scan and/or MRI Lab studies -- CBC, platelet count, PT/PTT Lab studies -- CBC, platelet count, PT/PTT Carotid studies Carotid studies Carotid ultrasound Carotid ultrasound Carotid angiography Carotid angiography Cardiac studies Cardiac studies Electrocardiogram Electrocardiogram Echocardiography Echocardiography

18. Cardiac evaluation of patients with TIA's or stroke (Sirna S et al, Stroke 14-23, 1990) Cardiac evaluation of patients with TIA's or stroke (Sirna S et al, Stroke 14-23, 1990) Strong association between carotid and coronary artery disease Strong association between carotid and coronary artery disease Cardiac events often determine the fate of the TIA patient. Cardiac events often determine the fate of the TIA patient. Abnormal exercise EKG's = 28% in patients with TIA's and no known cardiac symptoms. Abnormal exercise EKG's = 28% in patients with TIA's and no known cardiac symptoms. Abnormal stress or dipyridamole thallium studies = 45% in patients with TIA or mild stroke and no apparent heart disease. Abnormal stress or dipyridamole thallium studies = 45% in patients with TIA or mild stroke and no apparent heart disease.

19. ACC/AHA Gudielines on Peri-operative Cardiovascular Evaluation and Care for Non-Cardiac Surgery (Fleisher LA et al, Circulation 116: e418-99, 2007) ACC/AHA Gudielines on Peri-operative Cardiovascular Evaluation and Care for Non-Cardiac Surgery (Fleisher LA et al, Circulation 116: e418-99, 2007) Active Cardiac Conditions a. Unstable coronary syndromes a. Unstable coronary syndromes (unstable or severe angina, recent MI) (unstable or severe angina, recent MI) Decompensated heart failure Decompensated heart failure Significant arrhythmias Significant arrhythmias Severe valvular disease Severe valvular disease (severe aortic stenosis, symptomatic mitral stenosis) (severe aortic stenosis, symptomatic mitral stenosis) Functional Capacity Functional Capacity a. If there are no “active cardiac conditions” and the functional capacity is > 4 METs without symptoms, proceed with planned surgery. a. If there are no “active cardiac conditions” and the functional capacity is > 4 METs without symptoms, proceed with planned surgery. b. If the functional capacity is < 4 METs or unknown: b. If the functional capacity is < 4 METs or unknown: CEA is considered to be “intermediate risk surgery” (reported cardiac risk = 1-5 %) CEA is considered to be “intermediate risk surgery” (reported cardiac risk = 1-5 %) Clinical Risk Factors include: Clinical Risk Factors include: H/o ischemic heart disease H/o ischemic heart disease H/o compensated or prior heart failure H/o compensated or prior heart failure H/o cerebrovascular disease (i.e., carotid stenosis) H/o cerebrovascular disease (i.e., carotid stenosis) diabetes mellitus diabetes mellitus renal insufficiency renal insufficiency With 1 or more clinical risk factors, “Proceed with planned surgery with HR control or consider non-invasive testing if it will change management.” With 1 or more clinical risk factors, “Proceed with planned surgery with HR control or consider non-invasive testing if it will change management.”

20. Intraoperative management Intraoperative management Three main goals of anesthesia for CEA surgery -- to protect the heart from ischemia, to protect the brain from ischemia, and to have the patient awaken quickly at the end of surgery (Roizen MF, Anesthesia for Vascular Surgery, In: Barash PG et al (eds.), Clinical Anesthesia, 1989, pp. 1015-47). Three main goals of anesthesia for CEA surgery -- to protect the heart from ischemia, to protect the brain from ischemia, and to have the patient awaken quickly at the end of surgery (Roizen MF, Anesthesia for Vascular Surgery, In: Barash PG et al (eds.), Clinical Anesthesia, 1989, pp. 1015-47). Protect the heart from ischemia. Protect the heart from ischemia. Maintain normal hemodynamics, oxygenation, and ventilation. Maintain normal hemodynamics, oxygenation, and ventilation. Myocardial oxygen supply and demand balance (Thys DM, Kaplan JA. Cardiovascular Physiology. In: Miller RD (ed), Anesthesia, 3rd. Ed. NewYork: Churchill-Livingstone, 1990, pp. 551-83.) Myocardial oxygen supply and demand balance (Thys DM, Kaplan JA. Cardiovascular Physiology. In: Miller RD (ed), Anesthesia, 3rd. Ed. NewYork: Churchill-Livingstone, 1990, pp. 551-83.) Avoid factors that decrease myocardial O2 supply Avoid factors that decrease myocardial O2 supply Avoid factors that increase myocardial O2 demand Avoid factors that increase myocardial O2 demand

21. . A high percentage of CEA candidates have coexisting severe or advanced CAD, even with no history or EKG evidence

22. Protect the brain from ischemia. Some guidelines: Protect the brain from ischemia. Some guidelines: (Wendling WW,Carlsson C. Guidelines for anesthesia and cerebral protection in neurovascular surgery. In: Rosenwasser RH et al (eds.), Cerebral Ischemia: Clinical Implications andTherapeutics. Commack, NY: Nova Scientific Publishers, 1994, pp. 77-100) (Wendling WW,Carlsson C. Guidelines for anesthesia and cerebral protection in neurovascular surgery. In: Rosenwasser RH et al (eds.), Cerebral Ischemia: Clinical Implications andTherapeutics. Commack, NY: Nova Scientific Publishers, 1994, pp. 77-100) Maintain a normal or high normal blood pressure. Maintain a normal or high normal blood pressure. Maintain normocarbia or slight hypocarbia. Maintain normocarbia or slight hypocarbia. Avoid extreme hyperglycemia. Avoid extreme hyperglycemia. Monitor for cerebral perfusion. Monitor for cerebral perfusion. Treat cerebral ischemia if it occurs. Treat cerebral ischemia if it occurs. Have the patient awaken quickly after the operation. Have the patient awaken quickly after the operation.

23. Premedication -- "light" premedication is recommended, to permit: Premedication -- "light" premedication is recommended, to permit: Neurologic assessment during regional anesthesia. Neurologic assessment during regional anesthesia. Fast "wakeup" after general anesthesia. Fast "wakeup" after general anesthesia.

24. Monitors: Use routine monitors as reminder for additional monitors.

25. Does regional or general anesthesia for CEA have a better outcome? Results of the GALA (General Anaesthesia vs. Local Anaesthesia) Trial (GALA Trial Collaborative Group. Lancet 372: 2132-42, 2008): Primary outcome (stroke, MI, or death) – no significant difference – –General anesthesia (4.8 %) – –Local anesthesia (4.5 %) 4.4 % of patients under local anesthesia had complications that led to cancellation of surgery or conversion to GA. Stroke was a more common complication than MI after CEA.

26. Advantages and Disadvantages of Regional or General Anesthesia Advantages and Disadvantages of Regional or General Anesthesia Regional anesthesia. Regional anesthesia. a. Advantages a. Advantages Awake patient Awake patient Airway reflexes preserved Airway reflexes preserved Intraoperative neurologic exam is possible. Intraoperative neurologic exam is possible. Less post-op BP problems (?) Less post-op BP problems (?) Shorter ICU stay (?) Shorter ICU stay (?) Shorter hospitalization (not borne out by GALA trial) Shorter hospitalization (not borne out by GALA trial)

27. b. Disadvantages (Roizen MF. Anesthesia goals for operations to relieve or prevent cerebrovascular insufficiency. In: Roizen MF (ed), Anesthesia for Vascular Surgery. New York: Churchill-Livingstone, 1990, pp. 103-22.) b. Disadvantages (Roizen MF. Anesthesia goals for operations to relieve or prevent cerebrovascular insufficiency. In: Roizen MF (ed), Anesthesia for Vascular Surgery. New York: Churchill-Livingstone, 1990, pp. 103-22.) Need for patient cooperation Need for patient cooperation Possible loss of patient cooperation, with onset of new neurologic deficit, because of: Possible loss of patient cooperation, with onset of new neurologic deficit, because of: confusion confusion panic panic seizures seizures Inability to secure airway if panic, seizure, or oversedation occur Inability to secure airway if panic, seizure, or oversedation occur ! An unexpected delayed deficit may occur sometime after the test period. ! An unexpected delayed deficit may occur sometime after the test period. ! Inability to administer drugs such as thiopental that might protect the brain against ischemia ! Inability to administer drugs such as thiopental that might protect the brain against ischemia

28. General anesthesia General anesthesia a. Advantages a. Advantages Anesthetized, motionless patient Anesthetized, motionless patient Control of airway -- endotracheal intubation Control of airway -- endotracheal intubation Able to administer drugs such as thiopental to protect brain against ischemia. Able to administer drugs such as thiopental to protect brain against ischemia. b. Disadvantages b. Disadvantages Intra-op neurologic assessment impossible Intra-op neurologic assessment impossible Need sensitive and reliable monitoring for cerebral perfusion in place of awake neurologic assessment. Need sensitive and reliable monitoring for cerebral perfusion in place of awake neurologic assessment.

29. Regional Anesthesia for CEA Regional Anesthesia for CEA Techniques Techniques Local infiltration by surgeon Local infiltration by surgeon Superficial cervical plexus block Superficial cervical plexus block Deep cervical plexus block Deep cervical plexus block Combined superficial and deep cervical plexus blocks Combined superficial and deep cervical plexus blocks

30. Superficial cervical plexus block (Carron H et al. Regional anesthesia: Techniques and Clinical Applications. Orlando, FL: Grune & Stratton, 1984, pp. 10-15) Superficial cervical plexus block (Carron H et al. Regional anesthesia: Techniques and Clinical Applications. Orlando, FL: Grune & Stratton, 1984, pp. 10-15) Landmarks? Crossing of... Landmarks? Crossing of... External jugular vein and External jugular vein and Posterior border of sternocleidomastoid muscle Posterior border of sternocleidomastoid muscle Possible complications include: Possible complications include: Accidental injection into internal jugular vein. Accidental injection into internal jugular vein. Hematoma formation (tear in wall of vein) Hematoma formation (tear in wall of vein) Venous air embolus Venous air embolus Anatomy Anatomy Superficial cervical space communicates with the deep cervical plexus space. Superficial cervical space communicates with the deep cervical plexus space. Inject below the investing fascia, not just subcutaneously (Pandit et al. Brit J Anaesth 91: 733-5, 2003). Inject below the investing fascia, not just subcutaneously (Pandit et al. Brit J Anaesth 91: 733-5, 2003).

31. Deep Cervical Plexus Block (Carron H et al. Regional anesthesia: Techniques and Clinical Applications. Orlando, FL: Grune & Stratton, 1984, pp. 10-15) Deep Cervical Plexus Block (Carron H et al. Regional anesthesia: Techniques and Clinical Applications. Orlando, FL: Grune & Stratton, 1984, pp. 10-15) Landmarks? Landmarks? Line between mastoid process and suprasternal notch Line between mastoid process and suprasternal notch Aim perpendicularly for transverse processes of C2-C4. Aim perpendicularly for transverse processes of C2-C4. Possible complications? Possible complications? Recurrent laryngeal nerve paralysis = most common Recurrent laryngeal nerve paralysis = most common Stellate ganglion block = next most common Stellate ganglion block = next most common Cervical subarachnoid block with possible phrenic nerve block Cervical subarachnoid block with possible phrenic nerve block Direct injection of local anesthetic into vertebral artery, resulting in seizures or apnea Direct injection of local anesthetic into vertebral artery, resulting in seizures or apnea

32. General Anesthesia for CEA General Anesthesia for CEA A. Induction. Goal = to avoid extreme changes in blood pressure and heart rate. One suggested regimen: A. Induction. Goal = to avoid extreme changes in blood pressure and heart rate. One suggested regimen: Preoxygenate Preoxygenate Defasciculating or priming dose of non-depolarizing muscle relaxant. Defasciculating or priming dose of non-depolarizing muscle relaxant. Titrate anesthetics slowly. One possible regimen: Titrate anesthetics slowly. One possible regimen: Fentanyl Fentanyl Lidocaine Lidocaine Propofol or etomidate Propofol or etomidate Esmolol Esmolol Institute controlled ventilation with 100% O2. Institute controlled ventilation with 100% O2. Muscle relaxant for intubation: Muscle relaxant for intubation: Succinylcholine (unless patient has hemiplegia) Succinylcholine (unless patient has hemiplegia) Vecuronium or rocuronium (alternate choices) Vecuronium or rocuronium (alternate choices) Aim for smooth intubation Aim for smooth intubation

33. Maintenance. "Balanced anesthesia" = a reasonable choice Maintenance. "Balanced anesthesia" = a reasonable choice Volatile inhalational agent (isoflurane, sevoflurane, or desflurane) Volatile inhalational agent (isoflurane, sevoflurane, or desflurane) Nitrous oxide (?) Nitrous oxide (?) Narcotic (fentanyl) Narcotic (fentanyl) Nondepolarizing muscle relaxant (vecuronium or rocuronium) Nondepolarizing muscle relaxant (vecuronium or rocuronium)

34. Two Potential Intraoperative Complications Two Potential Intraoperative Complications Cardiac arrhythmias: Bradycardia -- during neck dissection Cardiac arrhythmias: Bradycardia -- during neck dissection Most likely cause = compression of carotid baroreceptor Most likely cause = compression of carotid baroreceptor Mechanism? Reflex involving: Mechanism? Reflex involving: CN IX (Glossopharyngeal) = afferent CN IX (Glossopharyngeal) = afferent CN X (Vagus) = efferent CN X (Vagus) = efferent Lidocaine injection of carotid baroreceptor by surgeon Lidocaine injection of carotid baroreceptor by surgeon Evidence of decreased cerebral perfusion -- during carotid clamping Evidence of decreased cerebral perfusion -- during carotid clamping Is monitoring for cerebral perfusion even necessary? Is monitoring for cerebral perfusion even necessary? These monitors have not been shown to improve outcome. These monitors have not been shown to improve outcome. Logic dictates that monitoring techniques assuring adequate cerebral function at the lowest myocardial work have a place in CEA surgery (Roizen MF, 1990). Logic dictates that monitoring techniques assuring adequate cerebral function at the lowest myocardial work have a place in CEA surgery (Roizen MF, 1990). Types of cerebral perfusion monitors Types of cerebral perfusion monitors Raw 16-20 lead encephalogram (EEG) Raw 16-20 lead encephalogram (EEG) Considered to be the "gold standard" monitor Considered to be the "gold standard" monitor Disadvantages: Disadvantages: Need specially trained personnel Need specially trained personnel Electrically "noisy" OR environment Electrically "noisy" OR environment Bulky equipment Bulky equipment Significant change = Significant change = > 50% reduction in EEG amplitude > 50% reduction in EEG amplitude flattening of EEG flattening of EEG

35. Processed EEG only monitors 2-4 channels. Processed EEG only monitors 2-4 channels. EEG electrodes placed on "watershed" areas EEG electrodes placed on "watershed" areas Still may miss ischemia during clamping Still may miss ischemia during clamping Somatosensory evoked potentials (Lam AM et al. Anesthesiology 75: 15- 21, 1991) Somatosensory evoked potentials (Lam AM et al. Anesthesiology 75: 15- 21, 1991) a) "Subtracts out" background EEG activity, leaving only the evoked potential from: a) "Subtracts out" background EEG activity, leaving only the evoked potential from: median nerve (wrist) median nerve (wrist) posterior tibial nerve (ankle) posterior tibial nerve (ankle) Significant change = Significant change = > 50% reduction in amplitude > 50% reduction in amplitude flattening of SSEP flattening of SSEP Similar sensitivity and specificity to EEG Similar sensitivity and specificity to EEG Both SSEP's and EEG are associated with a considerable false positive rate. Both SSEP's and EEG are associated with a considerable false positive rate.

36. Stump pressures Stump pressures Surgeon measures pressure in stump of carotid artery above cross-clamp. Surgeon measures pressure in stump of carotid artery above cross-clamp. Significant reduction = stump pressure < 50 mm Hg Significant reduction = stump pressure < 50 mm Hg Problem = poor correlation with EEG findings: Problem = poor correlation with EEG findings: False positives = stump pressure < 50 mm Hg with normal EEG False positives = stump pressure < 50 mm Hg with normal EEG False negatives = stump pressure > 50 mm Hg with "ischemic" EEG False negatives = stump pressure > 50 mm Hg with "ischemic" EEG May not adequately assess cerebral perfusion after stroke or RIND May not adequately assess cerebral perfusion after stroke or RIND Regional cerebral blood flow (Xenon washout) Regional cerebral blood flow (Xenon washout) only available in certain centers only available in certain centers indicates global well-being rather than focal cerebral ischemia indicates global well-being rather than focal cerebral ischemia Jugular venous oxygen saturation Jugular venous oxygen saturation ! global well-being rather than focal ischemia ! global well-being rather than focal ischemia Transcranial Doppler (to detect emboli or ischemia) Transcranial Doppler (to detect emboli or ischemia) Neurologic assessment under regional anesthesia Neurologic assessment under regional anesthesia

37. Responses to evidence of decreased cerebral perfusion. Responses to evidence of decreased cerebral perfusion. Surgeon can unclamp the carotid artery and insert shunt. a) Shunting during carotid endarterectomy -- three schools of practice: Surgeon can unclamp the carotid artery and insert shunt. a) Shunting during carotid endarterectomy -- three schools of practice: Shunt routinely. Shunt routinely. Shunt never, or very rarely. Shunt never, or very rarely. Shunt selectively, based on monitoring to detect cerebral ischemia. Shunt selectively, based on monitoring to detect cerebral ischemia. Advantage -- preserves carotid flow Advantage -- preserves carotid flow Potential risks: Potential risks: Thromboembolism Thromboembolism Intimal dissection Intimal dissection Thrombus formation Thrombus formation Air embolism Air embolism Obstruction of surgical field Obstruction of surgical field

38. CEA

39. CEA

40. CEA Shunt

41. Increase the mean arterial pressure Increase the mean arterial pressure Increases cerebral perfusion pressure Increases cerebral perfusion pressure Increases cardiac afterload and may precipitate myocardial ischemia. Increases cardiac afterload and may precipitate myocardial ischemia. So follow ST segments on EKG So follow ST segments on EKG Pharmacologic cerebral protection with thiopental Pharmacologic cerebral protection with thiopental Used more commonly for clipping of intracerebral aneurysms than for carotid endarterectomy Used more commonly for clipping of intracerebral aneurysms than for carotid endarterectomy Thiopental was cerebroprotective in one prospective randomized study in humans (Nussmeyer NA et al. Anesthesiology 64: 165-70, 1986). Thiopental was cerebroprotective in one prospective randomized study in humans (Nussmeyer NA et al. Anesthesiology 64: 165-70, 1986). Emergence -- Main concerns: Emergence -- Main concerns: Smooth and rapid awakening from general anesthesia, in order to obtain a neurologic assessment. Smooth and rapid awakening from general anesthesia, in order to obtain a neurologic assessment. Control of blood pressure Control of blood pressure

42. Post-operative considerations. Potential postoperative complications occur in 4 locations: Post-operative considerations. Potential postoperative complications occur in 4 locations: “In the arm.” “In the arm.” Hypertension = a very common complication Hypertension = a very common complication Incidence was 19% in one study. Incidence was 19% in one study. More common if patient was hypertensive preoperatively. More common if patient was hypertensive preoperatively. Hypotension – in approximately 5% of patients Hypotension – in approximately 5% of patients In the neck. Problems secondary to surgery on the neck: In the neck. Problems secondary to surgery on the neck: Wound hematoma – occurred in 5.5% of NASCET patients Wound hematoma – occurred in 5.5% of NASCET patients Paralysis of cranial nerves (VII, IX, X, or XII) Paralysis of cranial nerves (VII, IX, X, or XII) Carotid body dysfunction Carotid body dysfunction In the head. Cerebrovascular complications include: In the head. Cerebrovascular complications include: Carotid artery thrombosis Carotid artery thrombosis Emboli Emboli Stroke Stroke Hyperperfusion syndrome Hyperperfusion syndrome Manifests as severe unilateral headache, which is postural Manifests as severe unilateral headache, which is postural Related to preoperative hypoperfusion and loss of autoregulation Related to preoperative hypoperfusion and loss of autoregulation Seizures – relatively uncommon Seizures – relatively uncommon D. In the chest. Myocardial infarction often occurs D. In the chest. Myocardial infarction often occurs