Keywords
common carotid artery occlusion - vascular reconstruction - saphenous vein graft
Introduction
Common carotid artery (CCA) occlusion is relatively rare, being reported in 2 to 4%
of patients with symptomatic cerebrovascular disease.[1] As rich collateral blood flow often forms during the occlusion process, cerebral
ischemia is considered to be relatively rare. However, CCA occlusion can induce dynamic
changes in angio-architectural conditions. Once CCA occlusion becomes symptomatic
due to hemodynamic cerebral ischemia or distal embolization from the occlusion site,
it may be refractory to medical therapy.[2]
[3]
[4] Surgical treatment of symptomatic CCA occlusion should be considered and planned
according to the cerebral hemodynamic conditions.
We herein report the successful treatment of symptomatic CCA occlusion that was revascularized
by bridging bypass using a saphenous vein graft (SVG) between the distal CCA and proximal
cervical internal carotid artery (ICA).
Case Illustration
An 86-year-old woman experienced transient faintness. Screening magnetic resonance
angiography (MRA) revealed severe stenosis of the right distal CCA, while magnetic
resonance imaging (MRI) demonstrated no cerebral ischemic lesions. Three-dimensional
computed tomography angiography (3D-CTA) demonstrated severe right distal CCA stenosis
with circumferential calcification and a corkscrew-like irregular lumen. Observation
and conservative therapy with antiplatelet drugs were initially conducted.
Two years after the initial consultation, the patient developed frequent transient
left hemiparesis. MRA revealed short-segment occlusion of the right distal CCA to
the proximal cervical ICA ([Fig. 1A]), while diffusion-weighted imaging (DWI)-MRI demonstrated no ischemic lesions. 3D-CTA
demonstrated short-segment occlusion of the right distal CCA to the proximal cervical
ICA 3 cm in length with circumferential bulky calcification ([Fig. 1B, C]). There was no significant collateral blood flow via the anterior communicating
artery or posterior communicating artery. I123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (IMP-SPECT)
demonstrated a decreased resting cerebral blood flow (CBF) in the territory of the
right ICA to 90% of the contralateral ICA territory, and the CBF with Diamox challenge
showed a remarkable decreased cerebrovascular reserve capacity to −25% ([Fig. 1D]). We planned bridging bypass from the CCA to cervical ICA using a short SVG without
manipulating the occlusion site with circumferential bulky calcification. A 5-cm transverse
right cervical skin incision 2 cm below the mandibular angle was made, and the skin
incision was then elongated 3 cm to the rostral side along the anterior border of
the sternocleidomastoid muscle ([Fig. 2A]). The carotid bifurcation was exposed between the proximal cervical ICA 3 cm distal
to the bifurcation and the distal CCA 3 cm proximal to the bifurcation. A 6 cm SVG
was then harvested from the medial condyle of the right lower leg ([Fig. 2B]). A total of 3,000 units of heparin was administered intravenously. A 2.8-mm-diameter
hole was made with a vascular punch at the distal CCA 3 cm below the bifurcation after
clamping the CCA. End-to-side anastomosis between the SVG and distal CCA was made
using 6–0 Goatex sutures (clamping time: 20 minutes; [Fig. 2C]). Another 2.8-mm-diameter hole was then made with a vascular punch at the proximal
cervical ICA 2 cm distal to the bifurcation after clamping the ICA. End-to-side anastomosis
between the SVG and the proximal cervical ICA was made using 6–0 Goatex sutures (clamping
time: 24 minutes) ([Fig. 2D]). Indocyanine-green video angiography confirmed the patency of the graft.
Fig. 1 (A) A screening magnetic resonance angiography (MRA) 2 years before the onset of transient
ischemic attacks (TIAs) demonstrating a severe stenosis of the right distal common
carotid artery (CCA; arrow). (B) MRA obtained after the onset of TIAs demonstrating an occlusion of right distal
CCA to carotid bifurcation (arrowhead) without significant collateral flows. (C) Three-dimensional computed tomography angiography demonstrating the occlusion of
right distal CCA to carotid bifurcation (arrow) with patent proximal cervical internal
carotid artery (ICA) and external carotid artery. (D) A circumferential bulky calcification on the occlusion site. (E) I123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography demonstrating
a decreased resting cerebral blood flow (CBF) in the territory of the right ICA to
90% of the contralateral ICA territory. (F) CBF with Diamox challenge showing a remarkable decreased cerebrovascular reserve
capacity to −25%.
Fig. 2 (A) A 5 cm of transverse right cervical skin incision 3cm below the mandibular angle
was made, then elongated 3cm to the rostral side along the anterior border of the
sternocleidomastoid muscle. (B) A 6 cm of saphenous vein graft (SVG) was harvested in the medial condyle of the
right lower leg. (C) Intraoperative photograph demonstrating the SVG (arrow) anastomosed with the distal
common carotid artery (CCA) and arteriotomy in the proximal cervical internal carotid
artery (ICA; arrowhead). (D) A bridging bypass between the distal CCA and the proximal cervical ICA was completed
using short SVG.
The patient tolerated the operation well. She had no neurological symptoms. Postoperative
DWI-MRI demonstrated no ischemic lesions, and MRA ([Fig. 3A]) and 3D-CTA demonstrated an excellent bypass flow ([Fig. 3B]). Postoperative IMP-SPECT demonstrated a normal perfusion in the right ICA territory.
The patient experienced no transient ischemic attacks following the operation for
more than 1 year.
Fig. 3 Postoperative magnetic resonance angiography (A) and three-dimensional computed tomography angiography (B) demonstrating the good patency of the bridging bypass.
Discussion
Symptomatic CCA occlusion is relatively rare because of the rich collateral vessels
that develop during the occlusion process.[2] Once it becomes symptomatic, however, it is often refractory to medical therapy.
Riles et al first classified CCA occlusion based on its angioarchitecture and noted
differences in the surgical revascularization for each type of angioarchitecture.[5] Surgical revascularization should be determined based on a comprehensive understanding
of the hemodynamics, including the occlusion site, length of occlusion, and calcification
of the vascular wall.[6] The present case had distal CCA to carotid bifurcation occlusion with a patent proximal
cervical ICA and external carotid artery. The length of occlusion was relatively short
(3 cm) with severe circumscribed calcification. Carotid artery stenting through the
occluded segment was thought to have difficulty obtaining satisfactory dilatation
because of the severe circumscribed calcification.[7] Carotid endarterectomy was also thought to carry a significant risk.[8] We, therefore, decided to perform bridging bypass from the distal CCA to the proximal
cervical ICA using a SVG without manipulating the occlusion site with circumferential
bulky calcification. The bridging bypass was accomplished safely using a relatively
short SVG, and a sufficient bypass flow was confirmed on MRA and 3D-CTA. The short
SVG is easy to handle with proximal and distal anastomotic sites in a single operative
field. The radius of the vessel and the length of the graft influence blood flow,
and the length of the vessel influences the blood flow inversely, that is, a shorter
graft length provides more blood flow. A short SVG is also expected to prolong patency.
Bridging bypass using a short SVG might be useful for cases of short-segment CCA occlusion.
As the cervical carotid bifurcation was already totally occluded in this case, we
might not have to care about the occlusion time for making the bridging bypass. We
should rather focus on good quality of bypass.
Conclusion
Precise evaluations of the extent of the occlusion and collateral flow are important
for the treatment of symptomatic CCA occlusion, and the surgical strategy should be
determined based on the angioarchitecture and nature of the vascular wall. Bridging
bypass using the short SVG might be useful for short-segment CCA occlusion.
