Key-words: Carotid endarterectomy - carotid shunting - conventional carotid endarterectomy -
eversion carotid endarterectomy
Introduction
Carotid endarterectomy (CEA) is a surgical procedure done to prevent future embolic
stroke in patients with internal carotid artery (ICA) stenosis.[[1 ]] Conventional CEA (c-CEA) and eversion CEA (e-CEA)[[2 ]] are two surgical techniques used for the above. Most of the centers are performing
c-CEA routinely because it is performed under the protection of a carotid shunt and
is technically easier. Whenever the operative time gets prolonged in c-CEA, the brain
gets antegrade blood flow through the shunt. In c-CEA, the arteriotomy is always patch
closed, whereas in e-CEA, ICA is transected from the carotid bulb, endarterectomy
is performed, and ICA is primarily anastomosed to the carotid bulb in end-to-side
manner. As carotid shunt is rarely used in e-CEA, a certain amount of cerebral ischemia
occurs in patients who were already having carotid stenosis. In this study, we have
evaluated the outcome of two surgical techniques in severe carotid stenosis.
Materials and Methods
A total of 62 patients who underwent CEA (c-CEA, n = 31; e-CEA, n = 31) in division
of vascular surgery between January 2018 and December 2019 for symptomatic ipsilateral
ICA stenosis ≥50% on computed tomography angiogram with or without contralateral ICA
stenosis/occlusion were included in this prospective nonrandomized study. All symptomatic
patients <50% ICA stenosis and all asymptomatic patients were excluded from the study.
The choice of e-CEA or c-CEA was decided based on the discretion of surgeons who performed
the procedure, and the preoperative evaluation was the same for both. Follow-up details
of all patients till the third month were included. A duplex scan was done at the
third month if any restenosis detected further treatment was initiated. Minor stroke
was defined as any new neurologic event that persists for <24 h but completely resolves
or returns to baseline within 30 days with National Institutes of Health Stroke Scale
(NIHSS) score of ≤4. Major stroke was defined as any new neurologic event that persists
for >24 h with NIHSS score >4.
Operative procedure details of conventional carotid endarterectomy
All c-CEAs were performed under general anesthesia. A longitudinal incision along
the anterior border of sternocleidomastoid muscles was made, carotid sheath was opened,
and common carotid artery (CCA) ICA and external carotid artery (ECA) were looped.
Neuroprotective medications such as methylprednisolone (30 mg/kg) and thiopentone
(1 mg/Kg) were administered and systemic heparinization was done. First ICA and then
CCA, followed by ECA, were clamped. Longitudinal arteriotomy was made from ICA extending
to the CCA [[Figure 1 ]]a. Pruitt Inahara shunt (Le Maitre® vascular, USA) was inserted [[Figure 1 ]]b and [[Figure 1 ]]c. The plaque was removed ensuring proper distal feathering. The arteriotomy was
closed using a supramalleolar great saphenous vein (GSV) patch [[Figure 1 ]]d. If the vein was not available, then bovine pericardial patch was used using a
continuous 6-0 Prolene suture. After proper de-airing, the clamps are released sequentially
ECA and CCA first, followed by ICA.
Figure 1: (a) Intraoperative picture showing ulcerated plaque and a free-floating thrombus
(blue, white, and yellow arrow indicate common carotid artery, internal carotid artery,
and external carotid artery end, respectively); (b) Pruitt Inahara shunt blue balloon
for common carotid artery and white balloon for internal carotid artery (Le Maitre®
vascular, USA); (c) Pruitt Inahara carotid shunt in situ in conventional carotid endarterectomy;
(d) Patch closure using saphenous vein patch in conventional carotid endarterectomy
Operative procedure details eversion carotid endarterectomy
All e-CEAs were also performed under general anesthesia. A transverse skin crease
incision is made centered over the carotid bifurcation. Dissection and order of clamping
were the same as in c-CEA. Here, ICA is then disconnected from the carotid bulb cutting
obliquely [[Figure 2 ]]a. Then, the assistant everts the ICA and endarterectomy is completed. This is followed
by distal CCA and ECA endarterectomy. ICA was then re-anastomosed to the side of the
CCA bulb in an end-to-side fashion using continuous 6-0 Prolene suture [[Figure 2 ]]b.
Figure 2: (a) Intraoperative picture showing atherosclerotic plaque in the internal carotid
artery during eversion carotid endarterectomy (blue, white, and yellow arrow indicates
common carotid artery, internal carotid artery, and external carotid artery end, respectively);
(b) Primary end-to-side anastomosis of the internal carotid artery to the carotid
bulb in eversion carotid endarterectomy (white arrow)
Statistical analysis
Student's t-test was used to compare the group's baseline characteristics and continuous
measures. Chi-square statistical analysis was used to compare the groups with discontinuous
variables. All statistical tests were two-tailed, and P < 0.05 was considered to represent
statistical significance. All data analyses were done using the Windows Excel 2010
and IBM SPSS Statistics, Version 26.0. Armonk, NY.
Results
Demographic profile
The study population was divided into eversion (n = 31) and conventional (n = 31)
groups and both the groups were statistically similar in comparison. A total of 58%
in e-CEA group and 58% within c-CEA group had a stroke prior to CEA (P = 1). The percentage
of patients with transient ischemic attack (TIA) was 41.9% in e-CEA and 43.3% in c-CEA
group (P = 0.912). Hence, the number of patients with stroke and TIA were similar
in both the groups (P = 1.00). Demographics data are listed in [[Table 1 ]].
Table 1: Demographic profile
Carotid endarterectomyin bilateral carotid disease
The patients with asymptomatic contralateral carotid stenosis were 19.35% in e-CEA
and 29.03% in c-CEA. There were two patients in c-CEA and one patient in e-CEA with
Contralateral (C/L) ICA occlusion. There was no statistically significant difference
in the number of patients with bilateral carotid stenosis in both eversion and c-CEA
(P = 0.263). The right- and left-sided CEAs were matched in both eversion and conventional
groups (P = 0.793); [[Table 2 ]].
Table 2: Carotid endarterectomy in bilateral carotid disease
Primary endpoint of the study
There was no major stroke or stroke-related death in both the study groups. One patient
in e-CEA had carotid occlusion and presented with minor stroke [[Table 3 ]].
Table 3: Primary endpoint of the study
Secondary endpoints of the study
There was no statistically significant difference in the secondary endpoints like
minor stroke (e-CEA n = 1 [3.2%], c-CEA n = 1 [3.2%], P = 1), TIA (e-CEA n = 1 [3.2%],
c-CEA n = 0, P = 0.3), postoperative Myocardial Infarction (MI) (e-CEA n = 1 [3.2%],
c-CEA n = 1 [3.2%], P = 1), hematoma (e-CEA n = 1 [3.2%], c-CEA n = 0, P = 0.313),
re-exploration (e-CEA n = 1 [3.2%], c-CEA n = 0, P = 0.313), and reperfusion syndrome
(e-CEA n = 1 [3.2%], c-CEA n = 1 [3.2%], P = 1). The incidence of cranial nerve dysfunction
was significantly higher in eversion group as compared to c-CEA (e-CEA n = 6 [19.4%],
c-CEA n = 1, [3.2%] P = 0.045) [[Table 4 ]].
Table 4: Secondary endpoints of the study
Difference in clamp time between eversion versus conventional carotid endarterectomy
The clamping time in e-CEA was significantly higher around (20.77 ± 8.504 min) as
compared to c-CEA (13.81 ± 6.332 min) and this difference was statistically significant
(P = 0.001); [[Table 5 ]].
Table 5: Clamp time in eversion-carotid endarterectomy and conventional-carotid endarterectomy
Discussion
All c-CEAs were performed with cerebral protection using intracerebral shunt and arteriotomy
closed with supramalleolar GSV patch. All e-CEAs were performed without shunt and
ICA is anastomosed primarily to CCA. The study showed that there were no statistically
significant differences in major stroke/carotid occlusion (3.2% [n = 1] in e-CEA and
3.2% [n = 1] in c-CEA) between two surgical techniques (P = 0.3) even though clamp
time in e-CEA was significantly higher (e-CEA = 20.77 ± 8.504 min vs. c-CEA = 13.81
± 6.332 min; P = 0.001). There was no difference in minor stroke, TIA, postoperative
MI, hematoma, re-exploration, and reperfusion syndrome between eversion and c-CEA.
Overall, there was no stroke-related death (n = 0) in both the study groups.
Our study results were similar to EVEREST trial which showed no differences in the
rate of perioperative stroke, TIA, MI, and death between e-CEA and c-CEA (1.3% for
each study group).[[3 ]] In the EVEREST trial, the clamp time in e-CEA was shorter (31.7 ± 15.9 vs. 34.5
± 14.4 min, P = 0.02) which is a contradiction to our study, in which clamp time in
e-CEA is longer. This is because all our c-CEAs are performed under shunt, the clamp
time is calculated by adding the time from carotid clamping to shunt insertion and
from shunt removal to completion of anastomosis. During the rest of the procedure,
the brain is getting antegrade cerebral blood through the shunt. The ischemia time
in e-CEA was calculated from the time of carotid clamping till the completion of procedure
as all e-CEA is done without shunt. In the EVEREST trial, the shunt was used only
in 16% of patients in c-CEA and 11% of patients in e-CEA.
In our study, even though the operative technique was different between the two groups,
in c-CEA group, all patients had shunts used and the same was not used in e-CEA. There
was no statistical difference in perioperative neurological outcomes between the study
population. Previous studies showed that intraoperative cerebral ischemia is a relatively
rare cause of intraoperative stroke during CEA when compared to embolic stroke.[[4 ]] A cerebral shunt can prevent only the ischemic stroke, but it will increase the
risk for embolic stroke if not inserted properly.[[5 ]] However, we are not denying the fact that when severe cerebral ischemia occurs,
it can lead to perioperative stroke, but cerebral embolism is the most common cause
of stroke during CEA shown in various studies.
A warning note is that we found significantly higher rate of cranial nerve injury
(CNI) in e-CEA group (eversion n = 6 [19.4%], conventional n = 1, [3.2%] P = 0.045).
In EVERST[[3 ]] trial, e-CEA neither resulted in a high rate of CNI nor caused more frequent neck
hematomas compared with c-CEA. The most common CNI in our study is a marginal mandibular
nerve (n = 4/6 in e-CEA and n = 1/1 in c CEA), followed by hypoglossal (n = 1; e CEA)
and recurrent laryngeal branch of vagus (n = 1; c CEA), but in majority of studies,
the most common CNI reported was vagus followed by hypoglossal nerve.[[6 ]] The major mechanism of CNI proposed was excessive use of electrocautery, excessive
retraction, injuries by forceps, or the application of arterial clamps. The vagus
nerve lies posteriorly in the carotid sheath, inadvertently may get entrapped in a
vascular clamp. Hypoglossal nerve injury occurs during the dissection of the distal
ICA in case of a high ending plaque, as the nerve crosses the upper part of the ICA.
In our study, the high incidence of marginal mandibular nerve dysfunction may be due
to the excessive upward traction for opening the transverse incision in e-CEA toward
the mandible where the nerve normally runs through. We recommend that longitudinal
incision is better so that it can be extended with ease in case of high ending plaque,
whatever the technique used for CEA.
The limitations of our study are that this is a nonrandomized study, and the sample
number was small. Furthermore, long-term follow is still required in these patients
to look for delayed complications of the two surgical techniques.
Conclusion
Our study showed that e-CEA is a safe technique even if the clamp time is higher when
compared to c-CEA. Furthermore, routine insertion of carotid shunt even though decreases
the cerebral ischemic time, it does not offer any additional advantage of decreasing
perioperative stroke when compared to nonshunting. The choice of the incision sometimes
had detrimental effects on cranial nerve function. Hence, the choice of the CEA technique
depends on the experience and familiarity of the individual surgeon as both the techniques
have their own advantages and disadvantages.
