Carotid Surgery

Objectives Pathophysiology of carotid dz Pathophysiology of carotid dz Strategy for anesthetic evaluation Strategy for anesthetic evaluation Perioperative management Perioperative management Complications Complications New therapies in the field New therapies in the field

Epidemiology 1.2m strokes or tia’s each yr in the US 1.2m strokes or tia’s each yr in the US >150,000 deaths each yr >150,000 deaths each yr 3 rd leading cause of death 3 rd leading cause of death CEA introduced in 1954 as a preventive measure for occlusive dz. CEA introduced in 1954 as a preventive measure for occlusive dz.

Indications >70% in symptomatic patients >70% in symptomatic patients % in symptomatic patients with low risk % in symptomatic patients with low risk >60% in asymptomatic patients with favourable surgical risks >60% in asymptomatic patients with favourable surgical risks

Physiologic considerations Carotid dz is due to atheroslerosis Carotid dz is due to atheroslerosis Most common site is the bifurcation of vessels Most common site is the bifurcation of vessels Ischemia is often due embolic phenomenon Ischemia is often due embolic phenomenon During ischemia collateral flow critical During ischemia collateral flow critical Principal pathways : Circle of Willis,extracranial anastomotic channels,leptomeningeal communications Principal pathways : Circle of Willis,extracranial anastomotic channels,leptomeningeal communications

Preoperative evaluation CEA has an inherent risk of perioperative stroke and cvs events CEA has an inherent risk of perioperative stroke and cvs events 25% strokes associated with CEA occur intra-op 25% strokes associated with CEA occur intra-op 33% mostly embolic; some hemodynamic in origin 33% mostly embolic; some hemodynamic in origin Recent data from the NASCET reports a 6.5% rate of stroke and death Recent data from the NASCET reports a 6.5% rate of stroke and death 1.1% rate of death, 0.9% disabling stroke,4.5% disabling stroke 1.1% rate of death, 0.9% disabling stroke,4.5% disabling stroke Increased risk for stroke is most strongly associated with an active neurologic process prior to surgical intervention Increased risk for stroke is most strongly associated with an active neurologic process prior to surgical intervention

Preoperative evaluation Other risk factors for poor neurologic outcome Other risk factors for poor neurologic outcome Hemispheric vrs retinal tia’s Hemispheric vrs retinal tia’s Left sided procedure Left sided procedure Ipsilateral ischemic lesion on ct Ipsilateral ischemic lesion on ct Contralateral carotid occlusion Contralateral carotid occlusion Impaired consciousness Impaired consciousness Poor collaterals Poor collaterals An irregular or ulcerated plaque An irregular or ulcerated plaque Cea with CABG Cea with CABG

Pre-op Medical complications occur 10% of time Medical complications occur 10% of time Hypertension: incidence of neurologic deficit related pre-op uncontrolled HTN Hypertension: incidence of neurologic deficit related pre-op uncontrolled HTN Multicenter study, diastolic>110 predictor of adverse events Multicenter study, diastolic>110 predictor of adverse events Reasonable recc is delay elective surgery for diastolics>110 Reasonable recc is delay elective surgery for diastolics>110 A less firm recc is to delay elective sx for sys >180 A less firm recc is to delay elective sx for sys >180 Carotid dz is a manifestaton of systemic dz: Good cardiac hx, previuos mi,angina,exs tolerance,chf,arrhythmias,ekg,cxr routine.Echo and stress test may be indicated as well. Carotid dz is a manifestaton of systemic dz: Good cardiac hx, previuos mi,angina,exs tolerance,chf,arrhythmias,ekg,cxr routine.Echo and stress test may be indicated as well. Diabetes, may have increased cardiac related death but data seems to indicate that CEA can be performed safely in these patients Diabetes, may have increased cardiac related death but data seems to indicate that CEA can be performed safely in these patients Renal Insufficiency, have a overall increased risk for stroke, death and cardiac morbidity Renal Insufficiency, have a overall increased risk for stroke, death and cardiac morbidity

Monitoring Awake patient Likely the gold standard for neurologic monitoring.However, there is absence of prospective data that will compel one to choose this method of neurologic monitoring EEG Neurologic changes may correlate with EEG. However, there is a fairly high rate of false positives for discriminating ischemia with the EEG SSEP Probably not any better than the EEG, but more complex. May be a better indicator of subcortical ischemia Stump Press Poor sensitivity/specificity TCD TCD may be beneficial for assessing hemodynamic ischemia,shunt function,embolic phenomenon,hyperperfusion syndrome Oximetry High false positive rate JvO2 Sensitivity,specificity and intervention thresholds not determined

Monitoring Std ASA monitors Std ASA monitors Continuous lead II, V5 Continuous lead II, V5 Arterial line routine Arterial line routine PA cath and TEE may be considered in patients with symptomatic dz or recent mi PA cath and TEE may be considered in patients with symptomatic dz or recent mi

Anesthetic Management No compelling advantage has been demonstrated with either regional or general anesthesia No compelling advantage has been demonstrated with either regional or general anesthesia Technique should optimize perfusion to the brain,minimize myocardial stress and allow rapid recovery Technique should optimize perfusion to the brain,minimize myocardial stress and allow rapid recovery Choice is often strongly influenced by the surgeon’s preference and the anesthesiologist familiarity with a specific technique Choice is often strongly influenced by the surgeon’s preference and the anesthesiologist familiarity with a specific technique Recent study, sevo and des provided quicker extubation times and recovery profiles after CEA c/w iso with no significant peri-op differnces in CI and ST segment analysis Recent study, sevo and des provided quicker extubation times and recovery profiles after CEA c/w iso with no significant peri-op differnces in CI and ST segment analysis Propofol and narcotics may be associated with hypotension Propofol and narcotics may be associated with hypotension

Regional technique A regional technique for CEA necessitates the correct combination of patient, surgeon and anesthesiologist A regional technique for CEA necessitates the correct combination of patient, surgeon and anesthesiologist CEA requires block of C2- C4. CEA requires block of C2- C4. Superficial cervical block, deep cervical, epidural and straight local or a combination of these have been utilized successfully Superficial cervical block, deep cervical, epidural and straight local or a combination of these have been utilized successfully

Regional technique Tangkanakul et al performed a meta – analysis of studies evaluating the efficacy and safety of regional anesthesia Tangkanakul et al performed a meta – analysis of studies evaluating the efficacy and safety of regional anesthesia The non-randomized study suggested that the use of regional was associated with approx 50% reductions in the odds of stroke, death, mi, pulmonary complications and length of hosp stay. The non-randomized study suggested that the use of regional was associated with approx 50% reductions in the odds of stroke, death, mi, pulmonary complications and length of hosp stay. There was far too little data to either confirm or refute the study. There was far too little data to either confirm or refute the study.

Modalities of Cerebral Protection Surgical- placement of a shunt during x-clamp Physiologic: Mild hypothermia 33-34C Rx hyperglycemia Rx hyperglycemia Hypertension Hypertension Hemodilution Hemodilution Maintenance of normocarbia Maintenance of normocarbia Anesthetic: Barbiturates, no evidence for permanent focal deficits volatile anesthetics, iso and sevo associated with lower critical bf volatile anesthetics, iso and sevo associated with lower critical bf c/w halothane and enflurane c/w halothane and enflurane Etomidate shown to worsen outcome in animal models,thio Etomidate shown to worsen outcome in animal models,thio shown to improve ischemic injury shown to improve ischemic injury Propofol, animal studies have produced mixed results Propofol, animal studies have produced mixed results

Post- op The objective is a smooth and prompt emergence with optimal systemic and cerebral hemodynamics, additional problems as follows: The objective is a smooth and prompt emergence with optimal systemic and cerebral hemodynamics, additional problems as follows: Hypertension Hypertension Hypotension Hypotension Myocardial Infarction Myocardial Infarction Stroke, usually embolic Stroke, usually embolic Bleeding Bleeding Cranial Nerve injury, occurs in 10% of patients Cranial Nerve injury, occurs in 10% of patients The most commonly injured nerves are,hypoglossal nerve,vagus, recurrent laryngeal,accessory nerve. The most commonly injured nerves are,hypoglossal nerve,vagus, recurrent laryngeal,accessory nerve. Unilateral damage usually no immediate sx or intervention Unilateral damage usually no immediate sx or intervention Bilateral damage could result in upper airway obstruction Bilateral damage could result in upper airway obstruction Beware of patients with pre- existing neck surgery Beware of patients with pre- existing neck surgery

CEA and CABG One of the more difficult decision matrices regards the patient who presents with simultaneous dz of the carotid and the coronary vessels regards the patient who presents with simultaneous dz of the carotid and the coronary vessels Best available evidence – doubling of risk of death or stroke if performed as a single anesthetic as opposed to a staged procedure anesthetic as opposed to a staged procedure In a staged procedure risk is related to which procedure is performed first: If CEA is performed first the risk of mi increases; if CABG is performed first the risk of stroke increases

Timing of CEA after Stroke Presently there is insufficient data to establish any guidelines Presently there is insufficient data to establish any guidelines In the 1980’s CEA patients typically stayed in the ICU for1-2days then floor 3-5days In the 1980’s CEA patients typically stayed in the ICU for1-2days then floor 3-5days Recent data has shown that 24hr ICU IS sufficient since most perioperative strokes following CEA occurred within 24hrs after the surgery Recent data has shown that 24hr ICU IS sufficient since most perioperative strokes following CEA occurred within 24hrs after the surgery

Summary Indications, symptomatic patients if stenosis>70% and for selected patients if the lesion is % Indications, symptomatic patients if stenosis>70% and for selected patients if the lesion is % Pre-op concerns, uncotrolled htn Pre-op concerns, uncotrolled htn Anesthetic technique no demonstrated advantage of regional vrs general Anesthetic technique no demonstrated advantage of regional vrs general Cerebral Monitoring, neurologic status in the awake patient, and the EEG may be considered close to the gold standard Cerebral Monitoring, neurologic status in the awake patient, and the EEG may be considered close to the gold standard Post op concerns, usually due to htn Post op concerns, usually due to htn Whichever anesthetic method is chosen, it is imperative that CBF be optimized, with min cardiac stress especially during x-clamping. Whichever anesthetic method is chosen, it is imperative that CBF be optimized, with min cardiac stress especially during x-clamping. The risk of ischemia may be decreased by maintaining normal to high perfusion pressure The risk of ischemia may be decreased by maintaining normal to high perfusion pressure

New Therapies Carotid stenting and Angioplasty, the procedure involves the placement of a saline filled balloon,pre-loaded with a stent under angiographic guidance and applying 15atm for 3mins, anesthetic technique is sedation Carotid stenting and Angioplasty, the procedure involves the placement of a saline filled balloon,pre-loaded with a stent under angiographic guidance and applying 15atm for 3mins, anesthetic technique is sedation Drawbacks, profound bradycardia, high incidence of strokes from the angiography alone. Drawbacks, profound bradycardia, high incidence of strokes from the angiography alone. SAPPHIRE (Stenting and Angioplasty with Protection at High-Risk for Endarterectomy) SAPPHIRE (Stenting and Angioplasty with Protection at High-Risk for Endarterectomy) First randomized trial to evaluate the safety and efficacy of carotid artery stenting with emboli prevention in high surgical risk patients. First randomized trial to evaluate the safety and efficacy of carotid artery stenting with emboli prevention in high surgical risk patients. High risk criteria included, prior cea, neck surgery, radiation to the neck, occlusion of the contralateral carotids, chf and other confounding medical problems High risk criteria included, prior cea, neck surgery, radiation to the neck, occlusion of the contralateral carotids, chf and other confounding medical problems

conclusion Study actually a randomized trial which compared cea with stenting and angioplasty Study actually a randomized trial which compared cea with stenting and angioplasty Enrollment terminated after 723 patients were enrolled, 416 registry and 307 randomized, as interim analysis showed a marked benefit in favour of stenting. Success defined as <30% residual stenosis Enrollment terminated after 723 patients were enrolled, 416 registry and 307 randomized, as interim analysis showed a marked benefit in favour of stenting. Success defined as <30% residual stenosis 30 day periprocedural combined stroke/mi/death rate which was the study endpoint was 5.8% in the stent group but 12.6% in the surgical group 30 day periprocedural combined stroke/mi/death rate which was the study endpoint was 5.8% in the stent group but 12.6% in the surgical group SAPPHIRE study SAPPHIRE study Showed that in high risk patients CAS was a superior to CEA and that emboli prevention was also improved in the CAS group of patients. Showed that in high risk patients CAS was a superior to CEA and that emboli prevention was also improved in the CAS group of patients.