Results of an Observational Study in Carotid Surgery UsingAbsorbable Suture Material

Marko Aleksic Æ Jan Uedelhoven Æ Vladimir Matoussevitch ÆThomas Luebke Æ Salvatore Tomagra Æ Barbara Krug ÆJan Brunkwall

Published online: 13 November 2008

� Societe Internationale de Chirurgie 2008

Abstract

Background Absorbable sutures are not well accepted for

reconstruction in high-pressure arterial segments because

the suture line might break and aneurysmal changes could

develop. This hypothesis was checked in the clinical setting

of carotid surgery.

Methods The morphology of the carotid artery was

evaluated by color-coded ultrasound in four groups of

patients: group A, 25 patients who underwent standard

carotid endarterectomy and patchplasty, including a trans-

verse plication for which absorbable sutures had been used;

group B, 10 patients who underwent eversion endarterec-

tomy and reinsertion using absorbable sutures; group C, 15

patients who underwent standard carotid endarterectomy

and patchplasty without a transverse placation; group D, 20

patients who suffered from atherosclerotic disease but did

not have previous carotid surgery or other carotid pathol-

ogy. All operations had been performed at least 3 years

earlier than the actual examination.

Results Along the internal carotid artery, where an

aneurysmal change would have been expected to occur, no

differences in absolute size or calculated elliptical cross-

sectional vessel area were found. Patients after eversion

endarterectomy did not show signs of aneurysmal changes

in the area of reinsertion at the carotid bifurcation.

Conclusions Even in the long-term, for this group of

patients, no significant aneurysmal changes of arterial

reconstructions in carotid surgery performed with absorb-

able sutures were observed.

Introduction

In cardiac and vascular surgery, mainly nonabsorbable

monofilament suture material, such as polypropylene or

ePTFE, is used to ensure a durable anastomosis. In only a

few circumstances, absorbable sutures are principally pre-

ferred, such as for growing individuals who require arterial

reconstruction [1, 2] or with complications at contaminated

anastomotic sites where after degradation of the suture the

infection is no longer supported [3]. The fear of suture line

breakage, which would lead to aneurysmal formation,

limits the use of absorbable sutures in adults, even when

autologous bypass material is used. However, the tensile

strength of modern absorbable sutures, such as polydiox-

ane, lasts for several months, when vessel healing should

be completed [4, 5].

Experimental studies have been performed in animals,

which verify that the rate and kind of complications do not

differ depending on the type of suture material [6], mainly

because the foreign body reaction caused by absorbable

sutures is less severe [7]. However, previously published

observational studies in humans that have examined dif-

ferent suture materials and their consequences for the

anastomosed vessel wall comprise mostly a maximal period

of less than 12 months [8, 9]. Therefore, this study was

designed to investigate the potential development of aneu-

rysmal changes in high-pressure and flow arterial segments

in the long-term when absorbable sutures had been used.

M. Aleksic (&) � V. Matoussevitch � T. Luebke � S. Tomagra �J. Brunkwall

Department of Vascular Surgery, University Clinic of Cologne,

Kerpener Str. 62, 50924 Cologne, Germany

e-mail: marko.aleksic@uk-koeln.de

J. Uedelhoven � B. Krug

Department of Radiology, University Clinic of Cologne, 50924

Cologne, Germany

123

World J Surg (2009) 33:145–149

DOI 10.1007/s00268-008-9794-3

For that purpose, the clinical models of 1) transverse

plication of the dorsal wall of the internal carotid artery

(ICA) during carotid endarterectomy (CEA) and patchplasty

and 2) eversion endarterectomy (EEA) and reinsertion were

chosen.

Materials and methods

There is no detailed information available about when to

expect an aneurysm to develop under the circumstances of

this study, which are not quite comparable to other inci-

dences where pseudoaneurysms are observed, such as

aortic surgery or arterial dissection. Considering the time of

approximately 3 months, during which absorbable sutures

remain detectable, any first sign of aneurysm development

would probably occur within the first year after surgery.

However, not a single case of early (within 1 year) post-

operative development of an ICA aneurysm has been

noticed in our practice. Therefore, we decided to focus on a

longer observation time and selected patients for a follow-

up examination, from the operation records of the Division

of Vascular Surgery, who were operated on at least 3 years

earlier.

Generally, CEA was performed only for high-grade

([70%) ICA stenosis. Patients with primary aneurysmal

disease of the carotid arteries were excluded from the

study.

The operations regularly took place under local anes-

thesia with selective shunt insertion only when patients

showed neurological changes during carotid cross-

clamping. When the carotid artery stenosis was combined

with elongation or kinking of the ICA, standard CEA was

followed by a transverse plication of the dorsal arterial

wall of the ICA to correct a lengthening of the vessel and

to fixate a remaining intimal flap. Practically, a running

suture adapted the ICA transversely between a distance of

approximately 5–10 mm, depending on the extent of

lengthening, where the spare and flexible part of the

vessel wall was flipped to the back. Because a transverse

plication was not part of the standard operative protocol,

it was left to the surgeon’s preference to perform it solely

based on the intraoperative estimation of the anatomical

situation for which a monofilament, absorbable suture

material prepared from a copolymer of glycolic acid and

trimethylene carbonate (MAXON�) size 7-0 was used

uniformly. Finally, the longitudinal arterotomy was closed

by a synthetic patch (DACRON�) using a monofilament,

nonabsorbable suture (PROLENE�, size 6-0) in all

patients who had undergone CEA.

Eversion endarterectomy (EEA), shortening and rein-

sertion of the ICA at the carotid bifurcation using

exclusively the same absorbable sutures, was performed

whenever the lengthening of the ICA was much more

pronounced than in the above-mentioned cases.

The morphology of the carotid artery was evaluated in

four different groups of patients as follows:

Group A: patients who had had CEA and patchplasty,

including a transverse plication.

Group B: patients who had had EEA.

Group C: patients who had had CEA and patchplasty

without a transverse plication. This group was used to

rule out a principle weakening of the arterial wall after

endarterectomy with aneurysm formation.

Group D: control patients from a cohort of patients who

were scheduled for reconstruction for peripheral occlu-

sive arterial disease, but who did not have previous

carotid surgery or known carotid stenosis.

The findings in this group of patients should reflect the

particular vessel anatomy in older, ‘‘normal’’ individuals

with atherosclerosis because no standard measures have

been defined. Examinations were performed by using

color-coded Doppler sonography where the visible parts of

the common, external, and internal carotid artery were

carefully investigated. The vessel diameter was measured

in three planes at six locations along the carotid artery

(Table 1; Fig. 1); the largest diameter measured at each

location (in mm) was used for further analysis and group

comparison.

Measurements at location 2 were considered appropriate

to assess the presence of aneurysmal changes due to the

performed transverse plication. Even if the transverse pli-

cation of the ICA had not been performed precisely 1 cm

distal to the carotid bifurcation, a relevant aneurysm, which

had developed because of this suture line, should have

reached that segment and, therefore, would be recorded.

Accordingly, the most distal part of the ICA was assessed

not to overlook an aneurysm.

An elliptical area F1 representing the approximated

vessel profile at the distal end of the patchplasty was cal-

culated at location 2 from the largest and smallest

diameters, x and y, according to the following equation:

F = pab, in which a = x/2 and b = y/2.

Table 1 Location of diameter measurement

Location Definition

Loc 1 Most distal accessible segment of ICA

Loc 2 ICA 1 cm distal to the carotid bifurcation

Loc 3 ICA at the carotid bifurcation

Loc 4 CCA at the carotid bifurcation

Loc 5 CCA 1 cm proximal from the carotid bifurcation

Loc 6 Most proximal accessible segment of CCA

CCA common carotid artery, ICA internal carotid artery

146 World J Surg (2009) 33:145–149

123

Aneurysms caused by the insertion of the ICA after EEA

would have developed most likely at the carotid bifurca-

tion, therefore, the maximal diameter and corresponding

cross-section area (F2) at location 4 were particularly

assessed.

Statistical analysis was performed by using SPSS�

(version 15.0; SPSS, Inc., Chicago, IL). Descriptive data

are presented as median and range. Differences between

groups were assessed by using the v2 test or Kruskal-Wallis

test for nonparametric parameters when appropriate.

P \ 0.05 was considered statistically significant.

Results

According to the predefined minimal duration of 3 years

between carotid surgery and the follow-up examination, a

total number of 427 patients with an uneventful course of

carotid surgery were evaluated. Based on the operative

notes, 32 patients had an additional transverse plication of

which 25 were examined (group A). Some patients who

fulfilled the inclusion criteria were reluctant to follow the

invitation despite numerous approaches. Having consulted

their family practitioner, no particular carotid pathology

was known at the present time. For the same reasons, only

10 of 14 patients in whom an EEA had been performed

constitute group B.

From the major group of patients who had CEA with

patchplasty, but without a transverse placation, 15 compa-

rable patients were selected as a sample survey to form

group C. Group D consisted of 20 other patients who had not

undergone carotid surgery who served as control subjects.

All patients had remained asymptomatic neurologically

after carotid surgery during the observation period and did

not develop a recurrent ICA stenosis.

The median duration between surgery and the follow-up

examination was 55 (range, 36–73) months and did not differ

between patient groups (group A: 55 (range, 36–72) months;

group B: 51 (range, 36–73) months; group C: 58 (range, 36–

61) months; P = 0.94; not applicable for group D).

Considering all four groups, 21 women and 49 men with

a median age of 74 (range, 50–84) years were examined.

The sex distribution (female/male) was not different

between groups (group A: 7/18; group B: 6/4; group C: 4/

11; group D: 4/16; P = 0.147). Patient age also did not

differ (group A: 77 (range, 52–84) years; group B: 70

(range, 64–84) years; group C: 75 (range, 50–81) years;

group D: 69 (range, 51–84) years; P = 0.08).

The anesthesiologists preoperatively assessed the

severity of comorbidities according to the ASA classifica-

tion. ASA II score was attributed to 16 patients (23%),

whereas 54 patients (77%) were classified as ASA III.

There were no differences between the groups regarding

the relation of ASA II/III score (group A: 5/20; group B: 0/

10; group C: 3/12; group D: 8/12; P = 0.09).

The largest of the three diameters, which were measured

at each carotid location, is presented in Table 2. This

maximal diameter was significantly different between the

patient groups only at two sites: 1) at the most distal seg-

ment of the ICA (location 1), which was not affected

surgically in any patient; patients in group D showed the

largest diameter (P = 0.02); and 2) at location 5; patients

in group A had the largest diameter representing the

1

2

3

4

5

6

10 mm10 mm

Common carotid artery

External carotid artery Internal carotid artery

Fig. 1 Scheme of measurements

Table 2 Comparison of largest diameter between different patient groups with regard to various locations along the carotid artery

Location Group A Group B Group C Group D P value

Loc 1 (mm) 5 (3.5–7.3) 5.2 (4.4–5.6) 4.1 (3–6) 5.3 (4.2–7.5) 0.02

Loc 2 (mm) 5.5 (3.5–7.4) 5.6 (4.7–6.7) 5 (3.2–7.2) 6 (4,5–8.7) 0.2

Loc 3 (mm) 7.3 (3.7–16) 6.8 (4.9–11.9) 7.4 (3,7–9.2) 6.6 (4.1–9) 0.49

Loc 4 (mm) 10.9 (6.2–20.3) 12.1 (6.5–18.7) 9.3 (4–15) 10.2 (7.9–15.8) 0.25

Loc 5 (mm) 9.2 (7–16.5) 8.6 (7.3–16.8) 9 (0.5–13.5) 7.9 (5.9–14.2) 0.02

Loc 6 (mm) 8.2 (6–12) 8.6 (6.7–9.9) 9 (5–14) 7.8 (5.9–12.9) 0.12

Data are medians with ranges in parentheses unless otherwise indicated

World J Surg (2009) 33:145–149 147

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proximal end of the patch (P = 0.02). However, no sig-

nificant differences had been noticed at locations 2 or 4,

where an aneurysmal change was most likely to occur.

Furthermore, the elliptical cross-sectional vessel area cal-

culated at these locations did not differ when patient groups

were compared (Table 3).

Discussion

The specific features of absorbable sutures were examined

in vascular surgery more than 25 years ago [10, 11].

However, long-term observational studies evaluating clin-

ical consequences had not been published, suggesting that

these sutures are not applied frequently or not investigated.

In the present descriptive study, the results of carotid

surgery were assessed when a transverse plication of

the dorsal wall or reinsertion of the ICA had been

performed with absorbable suture material. In case of

suture line breakage in this high-pressure and flow zone,

the development of local aneurysmal changes could be

anticipated. However, we did not observe such changes in

the region of interest, when the carotid morphology of

patients who were subjected to this kind of suture was

compared with those in whom a simple patchplasty or no

carotid surgery at all had been performed. With the

synthetic patch ventrally fixated with nonabsorbable

sutures, one could have expected a particularly asymmetric

development of aneurysms of the backside. Likewise,

reinsertion of the ICA with absorbable sutures after EEA

would lead to a localized aneurysm formation. However,

neither the absolute vessel diameter nor the elliptical

transection area differed between the groups. The only

differences were recorded at the proximal end of the patch

(as expected) and at the surgically untouched, most distal

segment of the internal carotid artery, which remains

unexplained.

In an early animal study in piglets, dilatation of an aortic

anastomotic site was seen when absorbable sutures were

used, and the tensile strength of those sutures was lost

within 4 weeks [12]. The modern suture material that was

used in the present study maintains its integrity for

approximately 3 months, which ensures adequate healing

of an anastomosis between two biological vessels [13–15].

This process goes along with less foreign body reaction and

less necrosis than with nonabsorbable sutures as studied in

animal experiments [8, 16]. Moreover, it has been sug-

gested that absorbable suture material provides a more

physiological anastomosis because the compliance at the

anastomosis is better and the development of intimal

hyperplasia is less pronounced, leading to fewer stenotic

complications [8, 9, 16].

At present, absorbable sutures cannot be recommended

for connecting synthetic bypasses, but there is support for

its use in arterial or venous autologous anastomosis based

on the results of this long-term study. Moreover, in pedi-

atric vascular and cardiovascular surgery, absorbable

suture material is preferred to allow the arteries to grow

[17–19]. Absorbable sutures also should be considered for

repairs at infected anastomotic sites [20], after complete

removal of previously implanted synthetic bypass material.

Because of the retrospective design and small patient

groups, and because some patients could not be reached for

a follow-up examination, a selection bias cannot be

excluded for this study. However, adequate time had

elapsed between surgery and the follow-up examinations

for aneurysms to have developed. Because this did not

occur, we can assume that such changes do not appear and

were not underdiagnosed. Therefore, the use of absorbable

sutures in carotid surgery does not seem to be associated

with a significant increased risk of aneurysmal formation at

anastomotic sites.

Because of the department’s regime in carotid surgery,

no comparable group of patients was available in which the

transverse plication was accomplished completely with

nonabsorbable suture material. Clearly, this would have

been the most accurate way to perform such a study.

However, this factor would have been more important if

some aneurysmal development had been observed with the

use of absorbable sutures, which was not the case. Then,

one would have liked to know whether reconstructions with

nonabsorbable sutures also had shown such changes to

better assess the relationship between aneurysmal devel-

opment and the type of suture material.

This work was conducted as an observational study with

the purpose to draw attention to a particular problem in

vascular surgery with relevance in everyday practice. The

findings of this study could start a new discussion or be the

Table 3 Comparison of cross-sectional elliptical area between different patient groups at locations along the carotid artery representing the

transverse plication (loc 2) and reinsertion (loc 4)

Location Group A Group B Group C Group D P value

Loc 2 (mm2) 19 (8–36) 20.4 (14–31) 14.5 (6–39) 21.9 (11–36) 0.42

Loc 4 (mm2) 67.2 (27–196) 83.6 (31–117) 67 (10–150) 57.5 (37–159) 0.48

Data are medians with ranges in parentheses unless otherwise indicated

148 World J Surg (2009) 33:145–149

123

basis for future research regarding the use of absorbable

suture material in vascular surgery when autologous

material is being anastomosed.

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