C HAPTER External Carotid Endarterectomy: 53 Indications, Techniques, and Results

E, JOHN HARRIS, JR, and CHRISTOPHER K, ZARINS

Naturally occurring collatera l pathways con necting the external carotid artery branches and the intracran ial cerebral circulation are well recognized and have been demonstrated anatomically, angiographically, and physiologically by vari­ous flow detection devices. Under normal c ircumstances, all internal carotid artery blood flow is direc ted intracranially, and flow through the co ll ateral pathways is from intracranial vessels to the external carotid artery branches , Similarly, ocular blood supply is derived predominantly from the inter­nal carotid artery via the ophthalmic artery, Thus, normally the external carotid arteries do not contribute significantly to intracranial or ocular blood flow. In the case of internal carotid artery occlusion, the direction of flow in the collateral pathways reverses , and flow courses from the external ca­rotid branches to the intracranial branches of the internal carotid artery, Thus, with occlusion of the internal carotid artery, the ex ternal carotid artery may become an important source of blood flow to the brain.

Occlusive or atheromatous changes in the ex ternal carotid artery can lead to transient ischemic episodes or amaurosis fugax w hen they are ips ilateral to an occluded internal ca­rotid artery. These sym ptoms arise by the same physiologic mechanisms observed with the internal carotid artery , that is, embolization or hypoperfusion. A number of investigators have demonstrated the potential for increas ing cerebral blood fl ow in patients with ipsilateral internal carotid artery occlu­sion and external carotid artery stenosis by external carotid endarterec tomy .'-' Emboli zation to the external caro tid artery from the blind cul-de-sac of an occluded inte rnal carotid artery can al so be re lieved by external carotid artery endar­terectomy.

Thi s chapter focu ses on the indications, techniques, and results for external carotid endarterectomy pelformed alone for symptoms of cerebral or ocular ischemia with ipsi lateral internal carotid artery occlusion,

INDICATIONS

The indications for external carotid end arterectomy in­clude (1) ipsilateral transient ischemic attacks (hemispheric or ocular) or stroke in patients with occlusion of the ipsilat­eral internal carotid artery and severe external carotid artery stenosis;4--(' (2) ipsil atera l transient ischemic attacks (hemi­spheric or ocular) or stroke and occlusion of the ipsilate ral internal carotid artery and moderate stenosis of the external carotid artery with ulceration ;1 (3) ipsilateral transie nt ische­mic attacks (hemispheric or oc ul ar) or stroke, with a nonste­notic ipsilateral external carotid artery and thrombus within the cul-de-sac of the occluded ipsil ateral internal carotid artery (Table 53-1 ).4. 8 The most clear-cut indication fo r ex te rnal carotid artery endarterectomy is monocular amau ro­s is fugax in patients with ipsilateral internal carotid artery occlusion and a microem bol ic source in the ori gi n of the external carotid artery or the occluded carotid sinus, Other. less clear indications for external carotid artery end arrerec­

tomy include nonlaterali z ing hemispheric transient i sche m:~

attacks, global ischemia, adjunctive procedure to extra ~;-.:c­

nial-intracranial (EC-IC) bypass , and asymptomatic str . ~ prophylaxis." ~, 10 Reports in the literature have not ah\ _. clearly defined the indications fo r ex ternal carotid , endarterectomy .

PATIENT SELECTION

Selection for ex ternal carotid artery endarterec tl among patients with clear indications has relied on di a", r: ti c arteriography and duplex sonography for confirmari appropriate lesions of the ipsilateral internal and e.\t ­carotid arteries. In patients with less clear indicatioll ~

external carotid artery endarterectomy, adjunctive Stu _

such as rad iolabeled xenon (, " Xe) cerebral perfusion ~(" have been utili zed to aid the selection process. Patients a severe reducti on in total cerebral blood fl ow, as evide - . _ by the mXe scan, and with bi lateral internal carotid ;!­

occlusion and external carotid artery stenosis can occ _

TABLE 53-1, Indica tions for External Carotid Artery

Endarterectomy

Symptoms Anatomy

Ipsil ate ra l trans ient ischemic attack Hemi spheric Ocul ar

I psi lateral stroke He mi spheric Ocu lar

Ipsil atera l transient ischemic at tack Hemi spheri c Ocular

Ipsi late ral stroke He mispheric Ocul ar

Ips il a teral tran sient ische mi c attacks Hemispheric Ocular

Ipsi laternl s troke He mispheric Ocul ar

G lobal ischem ia

Ipsilateral ICA Occlusion

Ips il ateral ECA High-grade stenosis

Ips il ateral rCA Occ lusio n

Ipsilateral ECA High·grade stenos is

Ips il ate ral ICA Occl usion

Ips il atera l ECA Moderate stenosis with uL

Ipsilate ral ICA Occlusion

Ipsilatera l ECA Modera te stenosis with u • .

Ips il atera l ICA Occlusion with thromou, ­de-sac

Ips il ate ra l ECA No stenosis or lesion

Ipsilalera l ICA Occlusion wit h th rom t: ­

de-sac Ipsilate ra l ECA

No stenos is or lesion

Ips il atera l and contralatc r" Occlus io n

Either ECA High-grade s tenosis

ECA. ex terna l carotid artery ~ ICA, imernD i carotid artery.

418

419 External Carotid Endarterectomy: Indi cations, Techniques, and Results

~e nefit from external carotid artery endarterectomy to -~,:.'C total cerebral blood flow, Successful ex ternal carotid :""'\ fcvascularization can return blood flow, as measured

,\e scan , to normal in 80 percent of these patients, II In 'f: 0 these findin gs, the role of ex ternal carotid artery

_ ". lfltction in relieving nonlatera lizing symptoms, pre­-:...::'1 : secondary to hypoperfusion, is unclear and not an

-::1\ proven indication, Nonetheless, blood flow measure­. b: " "Xe scan may be helpful.

: ,CHNIQUES

E. :e rn al carotid endarterectomy, as with intern al carotid , endarterectomy, can be performed under general o r

. . J

.,nesthesia, depending on surgeon preference, Continu­n\'Qs ive blood pressure monitoring is preferred, The

artery bi furcation is exposed throLlgh one of two .:!.lld approaches: a transverse midcervical incision or a

= .udi nal inci sion a long the anterior border of th e sterno­18stoid muscle, Systemic anticoagulation with intra­

~ heparin is recommended prior to initiation of arterial __,i n, Technical considerations of importance in ex ter­~.!Iotid endarterectomy include mobilizati on and control -e branches of the external carotid artery, sufficient to -:j the arteriotomy up the ex ternal carotid artery beyond ,J,hta l edge of th e plaque, Placement of the arteriotomy ~ \aried, with the understanding that the goals of the

, ~cure are to exclude the cul-de-sac of the occluded ~al carotid artery as an embolic source, to perform a ,-J d thromboendarterectomy of the ex ternal carotid ar­

_ and to close the arteriotomy without narrowing the _'""i1al carotid artery, Since the ex ternal carot id arte ry be­~~ an important source of collateral cerebral blood flow

- inr crnal carotid artery occlusion, some surgeons have -nmended selecti ve use of an intraluminal shunt during

~--na l carotid arte ry revascularization,l>· 10 . 12 Such shunting _. 'l t1 ically di ffi cult because of the many side branches,

'113 11 s ize , and the distal tapering of the ex ternal carotid _ , . \Ve have not found intraluminal shunting to be neces­

-: based on continuolls electroencephalographic (EEG) -'I~ ring data, - -fee general techniques of external carotid artery endar­::-.:tomy meet these goal s, Our preferred technique begins - ...l il y with amputation of the occluded internal carotid ~" whose di stal end is ligated or oversewn, The arte­

:11: is ex tended from the origin of the internal carotid -::;::;, along both the common carotid and ex ternal carotid

" Thromboendarterectomy is performed as previousl y ~ . ri bcd, with eithe r primary closure or patch angioplasty - ; . 53-I), Patch angioplasties with the use of prosthetic

- ~ ri a l s (Dacron and pol ytetrafl uoroethylene), vein, and - .....ne rectomized internal carotid artery have been de­

- L C J 5 This techniq ue of external carotid artery endarterec­, el iminates the internal carotid artery cul-de-sac , allows

_ - . ':1 \'i sualization of the endpoint of the endarterectomy, - _ all ows the incision to be closed primarily or with patch - !1oplasty,

... second technique begins with a standard arteriotomy in . ,? -o mmon carotid artery, which is then extended along the

. .:-rna l carotid artery, Thromboendarterectomy is performed :. ndard fashion, The o rigin of the internal carotid artery

is then occluded intraluminally with inten'upted sutures at its starting point. The arteriotomy is then closed primarily, or if necessary, with patch angiopl as ty with any of the materials described (Fig, 53-2)6

A third technique includes internal carot id artery angio­plasty as an adjunct to closure of the endarterectomized external carotid artery, The internal carotid artery is mobi­li zed beyond the bifurcat ion and ligated at the distal limit of the dissec tion, A Y ·shaped arte riotomy is performed, with its base on the common carotid artery and the arms ex­tending along both the internal and external carotid arteries, Standard thromboendarterectomy is performed to inc lude all surfaces, The spatulated, transected internal carotid stump is then tapered to close the external carotid arteriotomy, fac ilitati ng a tapered transition from the common to the external carotid artery (Fig , 53-3),5 11

RESULTS

The first report of external carotid endarterectomy ipsilat­eral to an internal carotid artery occlusion is credited to BB Jackson,12 This article is inte resting for its prose and its desc ription of ex temal carotid angioplasty using the stump of the internal carot id artery, but it describes a procedure performed for thrombosis of the common and external ca­rotid arte ries in the face of long-standing internal caro tid artery occlusion, with excellent resu lts, rather than dis­cllssing external carotid endarte rectomy in regards to current indications, During this same period, the Baylor group was performing extemal carotid endarterectomy for hemispheric ischemic symptoms, both transient and fi xed , in patients with ipsilateral internal carotid occlusion and stenos is of the origin of the external carotid anery, 2 Ten patients were reported, nine of whom had external carotid endarterectomy and Dacron patch angioplasty, and one of whom had throm­boendarterectomy of both the common and ex ternal carotid arteries, Five of these patients had adjunctive vascular recon­struction of the contralateral carotid system, All patients were relieved of symptoms throu gh 5 years of follow-up, although a to percent 30-day mortality was reported,

Subsequent experience with external carotid endarterec­tomy for symptomatic occlusion of the interna l carotid ar­tery, while uncommon compared with the experience with inte rnal carotid endarterectomy, was notable for conflictin g results provided by combining multiple small seri es of mixed patien t populations,3 The problem with these results is that they included multiple adjunctive surgical procedures with external carotid endarterectomy, performed on patients with variabl e preoperative neurol ogic deficits that increased the perioperative stroke and mortality rates , More acceptable results have been obtained when ex te rnal carotid endarterec­tomy alone was performed to relieve speci fic hemispheric or retinal symptoms (Table 53-2),7

Connolly and Stemmer '• reported an operative series of 45 patients with internal carotid artery occlusio n, ipsilateral external carotid artery stenosis , and sy mptoms of ipsil ateral hemispheric ischemia, All patients underwent ex ternal ca­rotid endarterectomy, and half of the patients underwent attempts at ipsilateral internal carotid artery thromboendar­terectomy , Unfortunately, the morbidity and mortality rates for the majority of these proced ures were not reported, The

420 Extemal Carotid Endarte rec tomy: Indications, Techniques, and Results

FIGURE 53-1 , External carotid artery endarterectomy as performed through the origin of the amputated internal carotid artery, which is oversewn , T­arteriotomy can be ex tended along the ex ternal carotid art ery to enable visualization of the endpoint of the endarterectomy, The arteriotomy can be cI ,,",,,"_ primaril y o r with a patch,

authors did observe improved symptoms and durability of the external carotid endarterectomy in nine of these patients, with a 2- to 5-year follow-up,

The remnant internal carotid artery "stump" observed following occlusion of this vessel was recogni zed as a poten­tial source of embolic phenomena in 1978, Nine cases of ipsilateral hemispheric transient ischemia or ipsilateral amau­rosis fugax or both were recognized in patients with remotely occluded internal carotid arteries and a remnant "stump" greater than 5 mm in length B Seven of these patients under­went carotid bifurcation endarterectomy and either remova l or obliteration of the internal carotid artery stump, Among those seven patients, there were no perioperative strokes, all

symptoms were improved or resolved, and one patient h....J a fatal myocardial infarction 2 weeks after the operal i The remaining two patients were observed; one under\':_ chronic anticoagulation and died from myocardial infarct 18 months later.

COIl'elation of successful external carotid artery reva~_­

larization ips ilateral to an internal carotid artery occlu_: ­with improved regional cerebral blood flow was establi ~ h,:, _

in 1981, II Eight patients with internal carotid artery oc:-_­sion, ipsilateral ex ternal carotid artery stenosis, and ips". "­eral hemi spheric ischemic symptoms underwent external c_­rotid endarterectomy with no postoperative strokes mortality, all with improved or resolved symptoms,

421 Exte rnal Carotid Endarterectomy: Indica tions, Techniques, and Result s

- :-_ ~ : 53-2. Exte rnal carotid artery endarte rectom y as performed th rough an arteri otomy on the common carotid artery, and extended onto the ex tern al - .me r)' . After removal o f the plaq ue, the internal carotid artery orifice is obliterated with suture, as illustrated. The arteriotomy ca n be closed primaril y

, .•1 parch.

[ion cerebrography was obtained preoperatively and_.

:.:; ' -:operatively in five of these patients, with improvement

postoperative mean regional cerebral blood flow rate I patients and normalization of the mean regional cere­

--_ blood flow rate in 80 percent of these patients. c "uhusiasm for external carotid endarterectomy was tem­

by the cautionary report of Halstuk and coworkers.}

-

:.>ri

[he sUiface, they reported a 13.8 percent perioperative , . to' ra te and a 2.7 percent peri operative mortality rate in

s of 49 external carotid artery revasculariza[ions. The

.. -.:" KE 53-3. Externa l carotid artery endar­

_ . ~

..

..

_": 'c)my is accompli shed throu gh a V-shaped -. 10111 )" extending fro m the common ca­.. .inc ry onto the origins of both the exter­..nd interna l carotid arteries. After removal

plaque, the inte rnal carotid arte ry is tated and oversewn, and a segme nt of

~nd3 rterectomized inte rn a l carotid artery J fo r patch an giopiasty.

authors concluded that although external carotid artery end­arterectomy was technically easy, its use should be recom­mended with caution. Further review of these data identified several potential modifiers of the results. Only 29 patients had unilateral external carotid artery endarterectomy alone . The remaining 20 patients had additional procedures, includ­ing EC-IC artery bypass, inflow bypass from the supra-aortic trunks, and bilateral external carotid artery endarterectomies at the same operation. The majority of perioperative strokes and the only peri operative death occurred among these 20

422 External Caro tid Endarterectomy: Indica ti ons, Techniques, and Results

TABLE 53-2. Summary of Operative Results for External Caro tid Artery Endarterectomy Performed Without Adjunctive Surgical Procedures

study' Patients, n Mortality, n (%)t Stroke, n (%)t

Fi sher e t all.' Floriani et a l" Sali ani et a l II, Slerpeui et aJS Street et al" Rush et al9

Boontje et ai lK

Lamberth e t ai' Halsluk et al' Mclntyre et a i' O ' Hara et aiiO Barnett e t a i' Za rins e t al ii Dielhrich et ai' Totals

II 6

12 22 15 19 II 7

29 22 30 7 R 9

208

0 0 0 0 0 0 0 I (4 5) 0 0 0 0 0 0 0 0 0 2 (6.8) 0 0 0 0

I (14.3) 0 0 0

I ( III ) 0 2 (09) 3 ( 14)

':' For full bibliographic information. see reference list at end of chapler 730-day perioperali ve rnte.

patients. Among the 29 patients undergo ing external carotid artery endarterectomy alone, there were no perioperative dea ths, and 2 perioperative strokes (6.8%). One of these strokes occurred 3 days postoperatively in a patient who was maintained perioperatively and postoperatively on an intra­aortic ba lloon pump.

Similar information was provided by the Cleveland Clinic with their report of 42 external carotid artery revasculariza­tions performed in 36 symptomatic and 6 asy mptomatic patients. lo Among the 30 patients who had external carotid endarterectomy alone, the 30-day combined stroke and mor­tality rate was 0 percent. Among the 12 extended procedures requirin g adjunctive EC-IC bypass, supra-aortic trunk inflow bypass, or external carotid artery reoperation, there were five perioperative neurolog ic events and one perioperative death, for a 30-day combined stroke and mortality rate of 50 per­cent.

A collective review publi shed in 1987 attempted to further define the role of external carotid artery endarterectomy in patients with ips ilateral internal carotid artery occlusion and ips ilateral hemispheric or retinal ischemic symptoms.? Twenty-three series of external carotid artery revasculariza­tions were reviewed, and all cases with procedures other than external carotid artery endarterectomy or bypass were excluded from further review. Analysis of 195 external ca­rotid artery endarterectomies and 23 external carotid artery bypasses identified postoperative resolution of ischemic symptoms in 83 percent and marked symptomatic improve­ment in 7 percent of patients. The 30-day combined perioper­ative stroke and mortality rate was 7 percent, although sev­eral of these cases were from the Halstuk series,' and could be discounted for reasons cited earlier, lowering the com­bined stroke and morta lity rate to 5 percent. The best results were identified in patients undergoing external carotid artery revascularization for indications of retinal ischemia or spe­cific ipsilateral hemispheric ischemia. A separate retros pec­tive review of 24 published series of external carotid artery reconstructions identified 192 operations in which external carotid endarterectomy was not associated with other proce­dures; the 30-day combined stroke and mortality rate was 1.6 percent. 5

More recently, small series of patients have been re [ rL~

spectively revi ewed for outcome following external car l i~

artery endarterectomy for ipsilateral internal carotid arter occlusion and symptoms of ipsilateral hemispheric or re( i n~ ischemia. In three compiled series , 28 patients unden'. e­ex ternal carotid endarterectomy, all experienced reso lUl i ­of preoperative symptoms, and the 30-day combined S(ro'

and mortality rate was 0 percent. IJ . 15. 16 Another serie s r~­viewed 16 patients with visual ischemic di sturbances , i p'i l . ­eral internal carotid arte ry occlusion, and external car0: _ stenosis. I? One patient underwent external carotid arter \ b ­pass and 15 patients underwent external carotid artery e~ld~­terectomy, with no perioperative deaths, strokes, or rel' r: ischemic episodes. All patients were relieved of ocular is '\. _­mia postoperative ly , and two patients suffered recurrent ­aurosis fugax when their repairs thrombosed, one at 2-1 ­one at 53 months postoperatively.

External carotid artery endarterectomy performed in ­tients with ipsilateral internal carotid occlusion and nonl ....~-­alizing symptoms of hemispheric ischemi a has been in:-.­quent with poor results identified to date . Combini n!:! ;,.-_ series and review of Sterpetti and associ ates,S 18 ~f 3­patients (50%) undergoing external carotid artery endarte,~.­tomy for noniateralizing symptoms were fo und to have re _ from symptoms postoperatively .

Most recently, a series of 21 external carotid artery 10' 0----=­

terectomies in patients with ipsilateral internal carotid aJ.-= occlusion and symptoms of either ips ilateral amaurosi~ I'll.:_ ( 14) or ipsilateral hemispheric ischemia (7) was repor.~ The operations were performed sa fely, with no death, new strokes within 30 days of operation. Interestingl ) in :.­series, 14 percent of patients with amaurosis fuga\ 71 percent of patients with hemispheric ische mia we re ­improved after external carotid endarterectomy. The pate­and durability of external carotid endarterectomy were b~ ~ when patch angioplasty was used than when primary clo, was used .

CONCLUSION

Patients with internal carotid artery occlusion can de\ c ­ipsilateral amaurosis fuga x and ipsilateral transient ische

•

External Carotid Endarterectomy: Indica tions. Techniques, and Results 423

_: Idcks. In thi s setting, the external carotid artery becomes .ill important source of collateral blood flow to the ipsilateral =.e and cerebral hemisphere. Atherosclerotic occlusive dis­::-.J. ,e of the external carotid artery can lead to the develop­-;cnt of flow-limiting stenoses as well as ulcerating plaques. K 'len these occlusive disease changes are associated with -si lateral internal carotid artery occlusion, they can serve as

_ ~o urce of emboli to the ipsil ateral eye and cerebral hemi­'phere . The occluded internal carotid artery stump can also -o'f\ c as a source of emboli.

In patients with an occluded internal carotid artery, ipsilat­~ .:I a ternaJ carotid artery endarterectomy can improve cere­-- .11 and retinal perfusion or eliminate an embolic source. -:1:, successful endarterectomy should exclude the stump of ~~ occ luded internal carotid artery . Patch angioplasty of the

~";dJrterectomized external carotid artery is recommended. External carotid artery endarterectomy is indicated for the

--cJ!ment of ipsilateral amaurosis fugax or ipsilateral tran­:"n! ischemic attacks in the presence of an ipsilateral inter­

- _' carotid artery occlusion and either an ipsilateral signifi­. '1 ex ternal carotid artery stenosis or ulcerated plaque or - ' he presence of an internal carotid artery s tump with - -ombus. Morbidity and mortality rates for external carotid

: try e ndarterectomy are acceptable and are improved by ~_ u nctive bypass procedures and contralateral cerebral re­_ -: ularization procedures performed in association with the

~·I.l ...' rna l carotid artery endarterectomy. The rol e of external _J otid artery endarterectomy in relieving nonlateralizing . mproms of cerebral ischemia is incompletely defi ned, and -7 :Jrocedure likely is of little benefit.

REFERENCES

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2. Diethrich EB, Liddicoat JE, McCutchen JJ , et al: Surgica l significance of the ex ternal carotid artery in the treatment or cc:rebrovascular insu fficiency. J Cordia­,'osc Surg. 1968: 15 :2 13.

3. Halstuk KS , Ilaker WHo Littaoy FN: External carotid endanerec tomy. J Vase SlIrg. 1984; I :398.

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5. Sterpetti AV . Schultz RD , Feldhaus RJ : Ex ternal carotid endarterectomy: fndica· tions, lechnique. and late result s. J Vase SlIr!!. 1988;7:31.

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Surg. 1987;6: 158. 8. Barnett HJM. Peerless SJ , Kaufmann JCE: " Stump" of the internal carotid artery .

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of eXlerna l carotid endarterect omy . J Vase Stl rg. 1992:1 6:407. 10. O' Hara PJ. Hertzer NR , Be ven EG: Ex terna l carotid revasc ularization: Rev iew of

a len- year experience. J Vase Surg. 1985;2:709. II. Zarins C K, DelBeccarro EJ, John s L. et al: Increased cereb ral blnod fio ll' after

ex ternal carOl id artery revascularizati on. Surf:cry. 1981;89:730 . 12. Jackson BB : The external carotid as a brai n collateral. Am J SlIrg. 1967;1 13:375. 13. Fisher DF. Valentinc J, Patterson CB , et al: 1s external carotid endarterectomy a

durable procedure' l Alii J Suri!. t 986; 152:700. 14. Connolly JE, Stemmer EA: Enda rterectomy of the external carotid anery. Arch

SUl K 197 3: 106:799. 15. Floriani M. Giulini SM. Banardelli S. et al: Surgical treat ment of lesions obstruct·

ing the ex ternal carotid artery. J Ca rdiovasc SlIrg. 1989:30:4 14 . 16. Satiani B, Dos BM. Vasko JS: Reco nstruction of the external carotid artery. SlIrg

Cyneco/Obslel. 1987;164: lOS. 17. Street DL. Ri cotta JJ. Green RM: The role of externa l carot id revascul arization in

the treatment of ocular ischemi a. J Vuse Surg. 1987:6:280 . 18. Boo ntje AH: External ca rotid artery rev(lscularizalion in the treatment of ocular

ischemia. J ClIrdiol'osc Surg. 1992;33: 3 J5.