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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3748_Библиотеки_им_академика_М_И_Перельмана
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186
id
Ster
S. S. Hans
XI Nerve
Post belly digastric
nocleidomastoid
branch of occipital
artery
IX Nerve
XII Nerve
Occipital
artery
X Nerve
Omohyo
Ansa
cervicalis
Fig. 17.1 Surgical anatomy of the neck showing carotid bifurcation and surrounding structures
(internal jugular vein and nerves)
arterial blood pressure reexly. The carotid body, which lies behind the point of
division of the CCA, is a small brownish red structure which acts as a
chemoreceptor.
In most patients, the ICA is posterior or posterolateral to the external carotid
artery (ECA).
17 Carotid Endarterectomy
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The External Carotid Artery
The ECA begins opposite to the upper border of the thyroid cartilage between the
third and fourth cervical vertebral body and continues cephalad and anteriorly
behind the angle of the mandible between the tip of the mastoid process and the
angle of the jaw and divides into supercial temporal artery and maxillary arteries.
The ECA branches in order are superior thyroid (which may arise from distal CCA),
ascending pharyngeal (which may arise from ICA), lingual, facial, occipital, posterior auricular, supercial temporal, and maxillary artery (Fig.17.1).
The Internal Carotid Artery
The ICA is the primary source of oxygenated blood to anterior portion of the brain
and the orbits. The ICA is divided into the following seven segments: cervical (c1),
petrous (c2), lacerum (c3), cavernous (c4), clinoid (c5), ophthalmic (c6), and communicating (c7). Internal carotid artery ascends into the skull base and becomes
intracranial through the carotid canal of temporal bone. It continues anteriorly
through the cavernous sinus and divides into anterior and middle cerebral
artery (MCA).
Relationship ofNerves intheNeck toCarotid Arteries
The vagus nerve runs vertically down within the carotid sheath lying between the
internal jugular vein (IJV) and the ICA and inferiorly between the same vein and the
CCA.On the right side, it descends posterior to IJV and crosses the rst part of the
subclavian artery. On the left side, vagus nerve enters the thorax between the common carotid and subclavian arteries and posterior to the left brachiocephalic vein.
During the performance of carotid endarterectomy (CEA), the vagus nerve in the
lower portion of the neck may become more anterior than its usual posterior course
and thus may be subject to injury.
At the level of second cervical vertebral body, the vagus nerve gives its superior
laryngeal nerve branch which descends along the side of the pharynx rst posterior
and then medial to the ICA and divides into the internal and external laryngeal nerve.
The Glossopharyngeal Nerve
After its exit from the skull, it courses forward between the IJV and the ICA and
descends anterior to the ICA deep to the styloid process and may get injured during
the cephalad mobilization of the ICA during CEA for high plaque as it courses deep
188
to the styloid process. Injury to the glossopharyngeal nerve results in loss of sensation to the posterior one-third of the tongue and difculty swallowing, often requiring PEG tube placement.
S. S. Hans
The Accessory Spinal Nerve
After its exit from the jugular foramina, it runs posterolaterally behind the IJV in
majority of instances but in front of the IJV in some cases and very rarely passes
through the vein. It can be damaged in cases where IJV is more anterior in relation
to ICA in the upper portion of the neck.
Ramus Mandibularis
Ramus mandibularis or the marginal mandibular branch of the facial nerve runs
anteriorly below the angle of the mandible under cover of the platysma and can be
injured during CEA if incision is more anteriorly placed. It can also be injured
because of overzealous retraction of the tissues (stretch injury).
External Laryngeal Nerve
External laryngeal nerve is smaller than the internal laryngeal nerve and crosses the
origin of superior thyroid artery and supplies the cricothyroid muscle. Injury to the
external laryngeal nerve results in decreased pitch of the voice.
Hypoglossal Nerve
The hypoglossal nerve is usually posterior or posterosuperior to the common facial
vein and is often crossed superiorly by another vein which drains into the IJV.The
hypoglossal nerve curves around the sternocleidomastoid branch of the occipital
artery, and its division and ligation aid in mobilization of the ICA during CEA.In a
few instances, the hypoglossal nerve may be inferior in its course, close to the
carotid bifurcation, and, if not carefully dissected, may result in an inadvertent injury.
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Ansa Cervicalis
Ansa cervicalis is formed as a loop from the descending branch of the hypoglossal
nerve which contains bers of the C1. The descending branch is joined by the lower
root of ansa cervicalis from the second and third cervical nerves, thus forming a
loop. One may encounter anatomic variations in the ansa cervicalis with its superior
root arising from the vagus, and its division during CEA may result in hoarseness.
Indications
1. Patients with minor to moderate stroke (NIH stroke scale <15) in the distri-
bution of MCA (rarely anterior cerebral artery) in whom the neurological decit has plateaued. Carotid endarterectomy is rarely performed as
an emergency in patients with recent stroke, as medical optimization, and
edema around the area of the infarction should improve before undertaking
the operation. The risk of perioperative stroke in this group of patients is not
increased if CEA is undertaken within 2 weeks of the stroke. Previous published trials reported greatest benet of CEA within 2 weeks of the neurological event, and after 12weeks, the benet of CEA is considerably reduced.
MRI brain is essential unless patient has a pacemaker/debrillator
2. Transient contralateral motor or sensory decit or speech involvement with
spontaneous recovery. Transient loss of vision (amaurosis fugax) which may be
complete or partial. Typically, the symptoms last for a few minutes and at the
most, 1h. There is no evidence of infarction on MRI of the brain.
3. Asymptomatic high-grade ICA stenosis (>70%) in selected patients who are oth-
erwise good risk for the procedure and have at least 5years of life expectancy.
Following clinical evaluation, the patient should undergo carotid duplex imaging
and non-contrast CT scan of the head, followed by CT angiography of the neck
and head. MRI/MRA brain is often necessary for further evaluation in patients
who exhibit focal neurological symptoms and/or positive neurological ndings.
Anesthesia
The preference of cervical block anesthesia (CBA) over general anesthesia (GA)
during performance of CEA has been debated vigorously during the past few
decades. Recent results from GALA trial have not shown any superiority in the
outcome following CEA for either CBA or GA.We prefer CBA except in patients
with a high plaque (cephalad end of the plaque) at the level of second cervical vertebrae, those with anxiety disorder, patients with hearing loss, or patients with poor
command of English language for whom general anesthesia is preferred.
190
S. S. Hans
Positioning andIncision
A roll is placed between the scapulae to hyperextend the neck with occipital support. The neck is turned laterally to the contralateral side. In patients with “short
neck,” the shoulder is slightly pulled downward with a wide tape attached to the
shoulder with Mastisol adhesive (Eloquest, Ferndale, MI), and tape is then stretched
and temporarily attached to the railing on the side of the table near its distal end.
Incision
Three incisions are commonly used:
1. Vertical with slight angulation anteriorly at the lower end.
2. Oblique (starting 2cm behind the sternocleidomastoid at the upper end and end-
ing 2cm in front of the muscle). This incision is preferable (Fig.17.2).
3. Transverse incision.
Vertical incisions leave an unsightly scar, and transverse incisions may limit the
exposure in the event the plaque extends for a considerable distance superiorly or
inferiorly. The length of incision is determined by the level of carotid bifurcation in
relation to the cervical vertebrae, and the extent of the plaque in the ICA and the
CCA are determined by preoperative CT angiography. After dividing the platysma,
the external jugular vein is ligated and divided. In the upper portion of the incision,
the greater auricular nerve is preserved and mobilized posteriorly and superiorly.
Division of the greater auricular nerve will result in temporary sensory loss in the
corresponding lobule of the ear and angle of the jaw. Dissection plan is continued
along the anteromedial border of the sternocleidomastoid muscle. A self-retaining
Wheitlaner retractor is applied superiorly and one inferiorly. The dissection plane is
developed among the medial border of the IJV and is continued cephalad. Common
facial vein is encountered, and ligated and divided, and upper deep cervical lymph
nodes are mobilized posteriorly. As the carotid sheath is opened, vagus nerve is
visualized posterolaterally between the artery and the vein. Vagus nerve may
descend anteriorly as it courses inferiorly. External carotid artery is looped with a
silastic loop which is then pulled caudally and held with a hemostat on the drapes at
the chest wall. Ansa cervicalis is seen in the upper part of the dissection and is mobilized anteriorly. In the exposed area above the conuence of the common facial vein
to the IJV, small unnamed veins joining the IJV are ligated and divided followed by
division of the sternocleidomastoid branch of the occipital artery, and this helps to
mobilize the hypoglossal nerve cephalad. Local anesthetic (1% lidocaine) is inltrated around the carotid body to prevent bradycardia. Intravenous heparin
(100units/kgm) is administered by the anesthesia team monitoring of ACT.
17 Carotid Endarterectomy
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Fig. 17.2 Oblique incision
for carotid endarterectomy.
The superior part of the
incision is 2–3cm behind
the medial border of
sternocleidomastoid and
inferior part of the incision
is 2–3cm in front of the
medial border of
sternocleidomastoid
191
Shunt Placement
There are three approaches regarding the use of shunt to maintain cerebral perfusion
during carotid cross clamping:
1. Routine use of shunt
2. Selective use of shunt
3. Carotid endarterectomy without shunt
Surgeons using routine indwelling shunt generally perform the procedure under
GA and do not need measurement of stump pressure and EEG monitoring to assess
cerebral perfusion, but the ow through the shunt should be documented by the arterial Doppler. The disadvantage of routine use of the shunt is that it may interfere
192
21 Gauge
Fig. 17.3 Measurement of
stump (back) pressure with
proximal clamping of the
CCA and occlusion of the
ECA with a silastic tape
doubled on itself
S. S. Hans
needle
with visualization of the distal end of the plaque at the termination of the endarterectomy. In addition, shunt may cause intimal injury, dissection and atheroembolization from the proximal CCA to the brain.
For surgeons using selective shunt under GA, the stump pressure monitoring can
be performed by inserting a 21-gauge needle and clamping the common and external carotid arteries. Measurement of back pressure (stump pressure) is then performed with a help of a monitor (Fig.17.3). In general, patients with shunt stump
pressure of 40mmHg or above do not need placement of indwelling shunt during
CEA, unless they become hypotensive during the procedure. EEG monitoring with
measurement of median nerve provoked potentials is preferable in determining the
need for shunt in patients undergoing CEA under GA.
Under CBA, continuous neurological assessment can be performed by having
the patient squeeze with his contralateral hand with a toy that makes a “squeaky
noise.” If patient develops contralateral weakness or becomes unresponsive on
clamping of the CCA, a shunt is immediately placed. Carotid endarterectomy without shunt has been proposed by a minority of authors and has shown satisfactory
results in small series.
Types ofShunts
One of the original shunts used in carotid artery surgery is Javid™ shunt (Bard,
Tempe, AZ). The author prefers Sundt™ shunt (Integra, Plainsboro, NJ) because of
its exibility and ease of insertion. Some surgeons prefer small caliber
scissors
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193
Pruitt- Inahara® (LeMaitre Vascular, Burlington, MA) shunt with balloon occlusion
proximally and distally. Argyl carotid shunt (Cardinal Health Dublin, OH) is also
used by some surgeons.
Shunt Placement
Following placement of an angled vascular clamp to CCA and a Kitzmiller clamp
distally into the ICA, an arteriotomy incision is made into the distal CCA which
extends into the proximal ICA by angled Potts scissors (Fig.17.4). The smaller end
of the shunt is inserted into the ICA, and a small Javid clamp is applied, and retrograde bleeding occurs through the larger end of the shunt. This end of the shunt is
then inserted proximally into the CCA, and large Javid clamp is applied. It is to be
noted; silastic vessel loop has already been applied to the CCA and that can be
tightened around the CCA along with the larger Javid clamp (Figs.17.5, 17.6, and
17.7). Unless there are technical difculties, the cerebral ischemia time during
insertion of the shunt should be less than 2–3min. In patients in whom mid CCA is
found to have signicant plaque with possibility of ulceration, it is better to insert
the larger end of the shunt rst into the CCA and to extrude any plaque or debris and
then clamp the shunt with a Fogarty softjaw clamp before inserting the distal end
into the ICA to prevent plaque embolization.
Fig. 17.4 Arteriotomy in
the distal CCA and
proximal ICA with angled
POTTs scissors. Kitzmiller
or Yasargil clamp is
applied to the ICA
Incision
Potts
194
Fig. 17.5 Insertion of
shunt with smaller end of
the shunt into the ICA
upon release of the
Kitzmiller or Yasargil
clamp
S. S. Hans
Fig. 17.6 Application of
small Javid clamp around
the ICA below the bulbous
portion of the shunt. Blood
from the ICA is lling the
shunt and is coming out
the larger end of the shunt
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Fig. 17.7 Larger end of
the shunt inserted into the
CCA after release of the
proximal vascular clamp
and occlusion with silastic
vessel loop. Large Javid
clamp is applied around
the shunt, proximal to its
bulbous portion
195
Plaque is dissected with a Peneld dissector at the thickest portion of the plaque
and continued cephalad until the plaque thins out at its feathery end (Fig.17.8).
Plaque is sharply divided proximally in the CCA.In patients whom the distal end of
the plaque is not rmly attached to the arterial wall, a tacking suture is applied in a
U-shaped manner (Fig.17.9). Patch closure is performed by suturing patch to the
ICA with a 7-0 cardiovascular polypropylene suture with two needles, and a 6-0
cardiovascular polypropylene for closure of CCA with the patch till shunt prevents
further closure. The shunt is removed from CCA rst and then from ICA (Figs.17.10
and 17.11).
Unless the diameter of the distal ICA is greater than 5mm, arteriotomy should
preferably be closed with a patch graft (bovine pericardium patch, PTFE, or Dacron
patch). After patch closure is near completed, back bleeding for ICA should occur,
and after completion of suture line, CCA clamp is released to ECA rst before ow
is reestablished into the ICA.Heparin should be reversed with protamine sulfate
depending upon the results of the ACT.
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