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Chapter 22
Carotid Subclavian Bypass
TimothyJ.Nypaver
Carotid subclavian bypass historically was a procedure primarily performed in the
management of subclavian stenosis or occlusion. The main indication for carotid
subclavian bypass was most commonly for vertebral basilar insufciency (posterior
cerebral circulation) related to reduced perfusion to or retrograde ow (subclavian
steal syndrome) in the ipsilateral vertebral artery. Alternately, the procedure could
be performed for direct arm perfusion problems with ipsilateral arm exercise fatigue.
The common carotid artery (CCA) serves at the donor artery with pulsatile perfusion reestablished to the distal subclavian artery and thereby the vertebral artery.
Alternately, in instances of proximal carotid disease, the bypass can be used to
restore pulsatile perfusion to the CCA, improving perfusion to the anterior cerebral
circulation. In this instance, the subclavian artery serves as the donor artery. One
additional indication for the carotid subclavian bypass is the anatomic situation in
which the left internal mammary artery (LIMA) has been used (or is going to be
used) for the graft for coronary artery bypass in the presence of a proximal subclavian stenosis or occlusion. The bypass functions to maintain perfusion to the left
internal mammary which then supplies the coronary circulation.
While carotid subclavian bypass is still used in the setting of subclavian and
carotid occlusive disease, the most common indication in the endovascular era has
been with debranching procedures in which the subclavian orice, due to the need
to secure a proximal landing zone, is covered by the proximal extent of the thoracic
endovascular aneurysm repair (TEVAR) graft. Carotid subclavian bypass is typically performed a few days prior to the TEVAR but can be accomplished concomitantly if necessary. In instances in which upper extremity ischemic symptoms
develop post-urgent or emergent TEVAR, bypass is also warranted. Due to concern
over the potential of reducing spinal cord perfusion, in the elective situation, an
T. J. Nypaver (*)
Division of Vascular Surgery, Henry Ford Hospital, Detroit, MI, USA
e-mail: TNYPAVE1@hfhs.org
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2023
S. S. Hans et al. (eds.), Primary and Repeat Arterial Reconstructions,
https://doi.org/10.1007/978-3-031-13897-3_22
227
228
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Fig. 22.1 Completed
carotid-subclavian bypass
with graft placed behind
the left Internal
Jugular vein
T. J. Nypaver
aggressive approach to carotid subclavian bypass prior to TEVAR has been adopted.
Absolute indications for this bypass when TEVAR coverage of the left subclavian is
anticipated are (1) absent right vertebral artery; (2) small or diseased right vertebral
artery; (3) left vertebral artery which terminates in the posterior inferior cerebellar
artery (PICA); and (4) history of prior LIMA coronary graft. Carotid subclavian
bypass is notable for its excellent patency results and as a procedure which is generally well tolerated by the patient. Except for rare or extenuating circumstances, the
bypass is constructed with a prosthetic graft, either Dacron or expanded polytetrauorethylene (ePTFE) (the author’s preference). Finally, the graft, if properly positioned, tends to be very short, usually ≤3cm in length.
Surgical anatomy: The operation is performed through a single supraclavicular
incision and consists of exposure of the common carotid artery in the medial aspect,
exposure of the subclavian artery deep to the anterior scalene in the mid-aspect of
the wound, and a tunnel created posterior to the internal jugular vein (Fig.22.1).
Important structures which need to be identied and preserved from injury include
the vagus nerve (during exposure of the CCA), the phrenic nerve (during the subclavian exposure), and the thoracic duct (empties into the subclavian vein near the
conuence of the left internal jugular and the left subclavian vein).
Technical Aspects oftheOperation
The patient is positioned supine in a semi-Fowler position, and general anesthesia is
used. The arterial line, if utilized, should be placed in the opposite extremity. The
patient has a roll placed longitudinally between the shoulder blades with head
extension allowing for exposure and access to the supraclavicular area. The neck is
rotated to the contralateral side. The incision is made approximately 2cm lateral to
the sternal notch, at the medial border of the sternal head of the sternocleidomastoid
muscle (SCM), 1–2 cm above the clavicle proper, and extends approximately
6–8cm laterally (Fig.22.2). The platysma is divided linearly, and minimal skin ap
is made extending for approximately 2 cm laterally each direction under the
22 Carotid Subclavian Bypass
Fig. 22.2 Scalenus anticus is divided a few mm at a time near its insertion into the rst rib, carefully protecting the phrenic nerve
229
Fig. 22.3 Division of clavicular head of the Sternomastoid with exposure of scalne fat pad
platysma. The external jugular vein and the omohyoid muscle are identied and
divided in the mid-wound. The clavicular head of the SCM is identied and divided
with cautery to expose the underlying scalene fat pad (Fig.22.3). Dissection with
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T. J. Nypaver
careful mobilization of the scalene fat pad then ensues with mobilization of the fat
pad laterally initiated at the lateral border of the internal jugular. The scalene fat pad
is mobilized on its medial, superior, and inferior borders out to the lateral edge of
the anterior scalene (Fig.22.4). The phrenic nerve coursing on the anterior aspect of
the anterior scalene (within the investing fascia of the muscle) is identied, notable
for its lateral to medial course (Fig.22.4). The phrenic nerve is gently dissected for
a short distance (2–3cm) to allow for its minimal retraction and protection during
the division of the anterior scalene. The phrenic nerve should not be forcibly
retracted due to the risk of temporary or permanent diaphragmatic palsy. The thoracic duct is also encountered in this region coursing in the inferomedial corner of
the scalene fat pad and, if identied, is simply ligated with polyglactin sutures or
monolament proline (Fig.22.4). With careful protection of the phrenic nerve, the
anterior scalene muscle is dissected on its medial and lateral aspects as close as possible to its insertion on the rst rib. The muscle is divided a few millimeters at a time
protecting the phrenic nerve throughout this exercise (Fig.22.5). The author prefers
low power cautery; however, sharp division is also utilized, recognizing that the
subclavian vein lies just anterior to the anterior scalene muscle in the inferior wound
and should be protected. The anterior surface of the subclavian artery should now be
visible, and the artery is now dissected out for 3–4cm and encircled with vessel
loops to allow application of distal and proximal vascular clamps. All branches of
the subclavian artery are carefully preserved including the thyrocervical trunk; for
the purposes of the carotid subclavian bypass, the internal mammary or the vertebral
Fig. 22.4 Identication of the phrenic nerve coursing lateral to medially in the investing fascia
22 Carotid Subclavian Bypass
Fig. 22.5 Scalenus anticus
is divided a few mm at a
time near its insertion into
the rst rib, carefully
protecting the phrenic
nerve
Fig. 22.6 Exposure of the
CCA and subclavian artery
231
artery is infrequently encountered. It is important to keep the dissection close to the
artery as the pleurae are frequently just deep to the posterior aspect of the subclavian artery.
Next, the CCA is dissected out with the medial head of the SCM retracted medially—the artery is immediately medial to the jugular vein (Fig.22.6). The CCA is
dissected for 4–5cm circumferentially. There are no branches in this area, but one
needs to be careful to avoid the vagus nerve which lies posterior and in-between the
CCA and the internal jugular vein. With the CCA dissected out, the jugular vein is
mobilized on its posterior aspect to facilitate the tunnel for the prosthetic graft.
Typically, the author has used 6- or 8-mm ePTFE as the graft material, although a
similar sized Dacron graft can also be utilized.
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Fig. 22.7 End to side
anastomosis to the left
subclavian artery following
a longitudinal arteriotomy
in the subclavian artery
T. J. Nypaver
The author prefers to complete the subclavian anastomosis rst—the patient
receives 70 units/kg of intravenous heparin with an activated clotting time of
200–250s desirable. The mid and most apical segment of the subclavian artery is
used for the site of the anastomosis. The subclavian artery tends to be much more
friable than other arteries; superiorly oriented tension on the artery with either forceps, sutures, or vascular clamps is not well tolerated and is to be avoided. Atraumatic
vascular clamps are applied typically with an angled Debakey clamp or small
Debakey Derra vascular clamp (for the proximal subclavian artery), and the arteriotomy is performed with an 11 blade on the anterior surface (Fig.22.7). The end of
the graft is cut in a beveled Cobra-hood type fashion, and the anastomosis performed with either 5-0 or 6-0 proline, starting on the medial aspect rst. The author
prefers to do the initial sutures in a parachute fashion, placing a total of ve sutures
prior to gently pulling and tightening down the sutures. Again, excessive pulling or
traction can occur with resultant troublesome tears to the subclavian artery, especially if one is too aggressive. Once the anastomosis is completed, the proximal
artery and distal artery are vented through the graft, and the anastomosis is checked
for hemostasis. The graft will now be tunneled over to the CCA, and this is performed in a retro-jugular fashion; the graft is positioned superior to the phrenic nerve.
The graft is brought up to the CCA, and a site is selected on the artery that allows
the straightest and most direct course of the graft. The CCA is then clamped proximally and distally keeping the planned arteriotomy on the lateral aspect of the common carotid artery—this is facilitated by gentle rotation of the artery when applying
the vascular clamps. The bypass graft is anastomosed to the common carotid artery
in an end-to-side fashion using a continuous 5-0 or 6-0 monolament suture
(Fig.22.8). The anastomosis is begun on the center of the back wall, and the suturing continues along the back wall from the inside. Prior to completing the anastomosis, the common carotid artery is vented both proximally and distally. The
22 Carotid Subclavian Bypass
Fig. 22.8 End to side
anastomosis of the graft to
the CCA
233
anastomosis is completed, and ow is opened through the graft and through the
subclavian anastomosis, prior to restoring ow into the distal CCA.The CCA clamp
is well-tolerated, and electroencephalogram monitoring is not routinely used.
Heparin is reversed with protamine, and the wound is carefully observed for any
bleeding or any chyle leak. The scalene fat pad is returned to its original position,
and the platysma is closed with interrupted 3-0 braided polyglactin suture. The use
of a drain in this area is controversial; the author has used a drain frequently especially if any amount of lymph uid was encountered during the operation.
Carotid Subclavian Transposition
An additional attractive option for proximal subclavian artery occlusive disease is
the performance of a carotid subclavian transposition. When extending the landing
zone for TEVAR with anticipated coverage of the subclavian origin, carotid subclavian bypass is preferred and has been generally adopted. Carotid subclavian transposition has the advantage of avoiding a prosthetic graft, is performed with a single
anastomosis, and has reported superb patency rates. The procedure is slightly more
technically challenging due to the need for extensive mobilization of the proximal
portion of the subclavian artery with isolation of the internal mammary and vertebral arteries. With carotid subclavian transposition, there is the potential for ligation
of the inferior internal memory artery, and thus, this operation is contraindicated in
patients who have a left internal mammary artery coronary bypass graft. An adequate length of the subclavian artery proximal to the origin of the vertebral artery is
required to allow for mobilization of the subclavian artery (to the common carotid)
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T. J. Nypaver
as well as the requirement for oversewing of the proximal subclavian stump. The
mobilized subclavian artery will need to reach the common carotid artery without
tension.
Operative details: The operation is initiated in the same fashion as the carotid
subclavian bypass as detailed above. The subclavian artery will need to be dissected
and mobilized for an additional 3–5cm proximally, extending down proximal to
takeoff of the vertebral artery. If there is inadequate length of the subclavian artery,
the procedure can be abandoned in favor of a carotid subclavian bypass. Once the
mobilization is completed, the patient is systemically anticoagulated (70units/kg).
The proximal portion of the subclavian artery is clamped with an atraumatic vascular clamp. Once the clamps are secure, the subclavian artery is divided leaving a cuff
or 8–10mm to be oversewn. The proximal stump of this subclavian artery is carefully oversewn expeditiously with 5-0 proline; the author leaves the end sutures
long and brought out and attached to rubber shads prior to releasing the clamp to
conrm hemostasis and allow for control of the subclavian stump. Once hemostasis
has been achieved, the clamp is removed and sutures are cut. This is performed due
to the concern that the subclavian stump, once released, can retract into the thoracic
cavity and render control problematic. The distal subclavian is brought over to the
common carotid artery, again in a retro-jugular position. The anastomosis to the
common carotid artery is performed in the same fashion and technique as the carotid
anastomosis of the carotid subclavain bypass.
Complications
Complications of carotid subclavian bypass are relatively rare but would include
nerve injury (vagus nerve/phrenic nerve), kinking or incorrect positioning of the
graft, injury or tearing of the subclavian artery due to its fragility, operative violation of the pleurae, and lymphatic or chyle leak secondary to thoracic duct injury.
Injury or excessive traction on the vagus nerve could result in transient vocal cord
paralysis/paresis, while injury to the phrenic nerve can result in temporary diaphragmatic palsy. The graft is typically short and with proper positioning of the
anastomoses, and appropriate graft length should not have a kink or excessive
redundancy. If detected intraoperatively, this nding will mandate operation correction. Injury or tearing of the subclavian artery typically noted with pulling up on
sutures or with the inappropriate use of forceps will require patch (bovine pericardium) repair of the artery, maintaining the lumen of the subclavian artery. The subsequent subclavian anastomosis is performed in the middle of the patch. Injury to
the thoracic duct can result in troublesome chyle and/or lymphatic drainage; if identied during the operation, duct should be identied and ligated. If chylous drainage
is encountered postoperatively, the author has found that early reoperation with
ligation or clipping of the chyle leak or the thoracic duct is the most efcient and
expeditious manner of handling this complication.
22 Carotid Subclavian Bypass
235
Take-Home Points
1. Carotid subclavian bypass is a durable well-tolerated procedure utilized in the
management of symptomatic subclavian or carotid artery occlusive disease.
When one is able to cross the subclavian artery stenosis or occlusion successfully, endovascular revascularization is the preferred initial management. Carotid
subclavian bypass is reserved for recurrent disease, subclavian artery occlusion
(unsuccessful in crossing), or special circumstances related to the vertebral or
internal mammary ow. The bypass now is commonly employed in debranching
procedures in which the TEVAR graft is expected or anticipated to cover the
subclavian orice.
2. The operation is well tolerated through a single relatively small incision—how-
ever, the proximity of important structures including the vagus nerve, phrenic
nerve, brachial plexus, venous structures, and the thoracic duct renders this an
operation in which one has to be vigilant to avoid excessive traction or injury
that can result in nerve palsies or chyle leaks.
3. Prosthetic grafts, either Dacron or ePTFE, are the graft of choice.
Chapter 23
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De-branching Operations onSupra-aortic
Trunk
TimothyJ.Nypaver
1. Carotid-carotid bypass and carotid-carotid-subclavian bypass
2. Ascending aorto-arch vessel debranching
Indications forCarotid-Carotid Bypass
andCarotid-Carotid- Subclavian Debranching Procedures
andAscending Aorto- Arch Vessel Debranching Procedures
Carotid-Carotid Bypass andCarotid-Carotid-Subclavian Bypass
The carotid-to-carotid bypass is an infrequent operation which has gained some
level of popularity in the setting of debranching procedures to extend the landing
zone of thoracic endovascular aneurysm repair (TEVAR) grafts to a level proximal
to the origin of the left carotid off of the aortic arch. The complete list of indications
for carotid-carotid bypass are as follows: 1. occlusive lesions of the common carotid
artery (CCA) or brachiocephalic trunk (innominate artery) not amenable to direct
reconstruction or endovascular therapy; and 2. as a procedure to extend the landing
zone of TEVARs to a more proximal arch aorta with coverage of the left carotid,
often performed concomitantly with a left carotid to left subclavian bypass. In
patients with ostial left common carotid lesions, carotid-carotid bypass is typically
reserved for those in whom the left subclavian is not suitable as a donor vessel. The
indication for the bypass is symptomatic left proximal common carotid artery disease with manifestations of stroke or transient ischemic attack or global reduction
T. J. Nypaver (*)
Division of Vascular Surgery, Henry Ford Hospital, Detroit, MI, USA
e-mail: TNYPAVE1@hfhs.org
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2023
S. S. Hans et al. (eds.), Primary and Repeat Arterial Reconstructions,
https://doi.org/10.1007/978-3-031-13897-3_23
237
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