Cas cliniques

DOI of or1Service de

Louvain, Belgi2Service d

Louvain, Louv

CorrespondSurgery, UnivBelgium, E-m

Ann Vasc SurDOI: 10.1016/� Annals of V�Edit�e par ELS

Parapar�esie apr�es r�ealignement d’uneendoproth�ese thoracique pour uneendofuite de type III non reconnue

David Volders,1 Inge Fourneau,1 Kim Daenens,1 Sabrina Houthoofd,1 Geert Maleux,2

Andr�e Nevelsteen,1 Louvain, Belgique

Objectifs : Nous avons examin�e les raisons pour ne pas avoir retrouv�e une endofuite de type IIIsur l’imagerie conventionnelle et la pathophysiologie d’une parapar�esie apr�es le r�ealignementd’une endoproth�ese.M�ethodes et r�esultats : Un homme de 46 ans a �et�e trait�e par une endoproth�ese thoraciquepour la rupture thoracique d’une dissection chronique thoraco-abdominale de type B avecd�eg�en�erescence an�evrysmale. Au cours d’une deuxi�eme intervention, la revascularisationr�etrograde des art�eres visc�erales et r�enales a �et�e r�ealis�ee en association avec l’insertion d’uneendoproth�ese abdominale. Apr�es un r�etr�ecissement initial du sac an�evrismal, le diam�etre del’aorte thoracique a commenc�e �a croitre de nouveau. Les angioscanners cons�ecutifs ne mon-traient aucune endofuite. En raison d’une douleur dorsale insupportable, une exploration chi-rurgicale ouverte a �et�e effectu�ee. Celle-ci montrait une endofuite de type III. Le r�ealignement del’endoproth�ese thoracique a �et�e fait, mais une parapar�esie s’est d�evelopp�ee.Conclusion : Chez les patients pr�esentant une augmentation non expliqu�ee du sac an�evrys-mal, l’angio-IRM avec injection de produit de contraste paut permettre de documenter uneendofuite. Le concept de r�eseau de collat�erales peut expliquer les l�esions de la moelle �epini�erepar des modifications h�emodynamiques meme mineures.

CASE REPORT

A 46-year-old man was transferred to our university hos-

pital because of exacerbating acute thoracic back pain. At

arrival the patient was in a stable hemodynamic condi-

tion. Contrast-enhanced computed tomographic (CT)

scanning showed a thoracoabdominal aneurysm type II,

based on a chronic type B thoracoabdominal dissection.

The maximum diameter in the descending aorta was

iginal article: 10.1016/j.avsg.2009.08.016.

chirurgie vasculaire, hopital universitaire de Louvain,que.

e radiologie interventionnelle, hopital universitaire deain, Belgique.

ence : Inge Fourneau, MD, PhD, Department of Vascularersity Hospital Leuven, Herestraat 49, B-3000 Leuven,ail: Inge.Fourneau@uzleuven.be

g 2010; 24: 550.e5-550.e9j.acvfr.2010.11.005ascular Surgery Inc.EVIER MASSON SAS

80 mm. The maximum diameter in the supraceliac tho-

racic segment was 40 mm and that in the infrarenal

abdominal segment was 86 mm. There was a contained

rupture at the level of the sixth thoracic vertebra. There

were no signs of malperfusion of the viscera. He had a

history ofmorbid obesity in spite of a gastric bypass 2 years

before and bad tolerance of effort.

To avoid extracorporeal circulation and deep hypo-

thermia in this unfit patient, a hybrid therapy was plan-

ned in two stages, giving priority to the rupture. In a

first stage an 8mm silver-coated Dacron carotidecarotidesubclavian bypass (InterGard Silver�; Intervascular, La

Ciotat, France) was performed as an emergency pro-

cedure, immediately followed by deployment of three

thoracic stent grafts (Valiant� straight graft; Medtronic,

Minneapolis, MN) from just distal to the brachiocephalic

trunk to the level of the twelfth thoracic vertebra, proxi-

mal to the celiac trunk.

Two weeks later, a control CT scan showed a further

increase of the maximal thoracic diameter to 100 mm as

a result of the persistent distal dissection and a stable

maximum abdominal diameter. The residual abdominal

600.e5

Fig. 1. CT reconstruction of the renal and visceral

revascularization and thoracoabdominal stent graft.Fig. 2. Transverse CT section through the eighth verte-

bra (arterial phase) showing mural intraluminal throm-

bus (arrow) at the right.

600.e6 Cas cliniques Annales de chirurgie vasculaire

aneurysm was treated as an elective procedure. First,

through a median laparotomy, an iliorenalehepaticbypass was performed to the right using an 8 mm Dacron

graft (Gelsoft�; Vascutek, Inchinnin, UK). Second, an

iliorenalesuperior mesenteric bypass was performed to

the left using an 8 mm Dacron graft (Gelsoft). The pro-

cedure was finished with extension of the previously

deployed thoracic stent graft to the common iliac arteries

by an abdominal bifurcation stent graft (Valiant straight

and Talent� bifurcated graft, Medtronic) (Fig. 1). The

patient was discharged 1 month after this second inter-

vention in good condition. Recovery was uneventful.

Follow-up was planned with three-phase helical CT

scan and plain X-ray.

Three months after the first procedure, a control CT

scan showed good function of the stent grafts with

complete thrombosis of the false lumen, a slight reduction

of themaximal diameter of both the descending and abdo-

minal aorta (89 and 81 mm, respectively), no signs of

endoleak, and good opacification of the visceral bypasses.

A control CT scan at 7 months confirmed further shrin-

kage of the false lumen in both the thoracic and the abdo-

minal aorta (86 and 68 mm, respectively).

Fourteen months after the first procedure, a new

control CT scan showed an increased maximal diameter

of the descending aorta to 93 mm with appearance of

mural thrombus in the true lumen on the right (Fig. 2).

No endoleaks were observed. The maximal diameter of

the abdominal aorta was decreased to 60mm.At this point

no intervention was planned.

A new control CT scan 4months later showed a further

increase of the maximal diameter of the thoracic aorta to

98 mm without endoleaks and further enlargement of

the mural thrombus. Another control CT scan 1 month

later showed no further increase of the maximal diameter

but enlargement of the mural thrombus. Since the patient

was asymptomatic and there were no signs of endoleak,

this was considered as endotension and we decided to fol-

low the patient carefully with 3-monthly CT scans.

Another control CT scan 21months after the first inter-

vention showed a further increase of the maximal diame-

ter of the descending aorta to 110 mm, still without

detectable endoleak. Erosive damage of the anterior side

of the ninth and tenth thoracic vertebrae was detected

(Fig. 3). At none of these time points did plain X-ray

show any sign of stent fracture or migration.

Twenty-two months after the first admission, our

patient presented with unbearable paravertebral pain. A

new three-phase helical CT showed enlargement of the

known mural thrombus on the right of the true lumen of

the descending aorta as the only change compared to the

same investigation 1 month earlier. The tentative diag-

nosis was endotension with erosion of the vertebra.

At this time we decided to intervene and to drain the

aneurysm in order to relieve the pressure on the vertebral

column. We had no evidence at all for a structural graft

defect. A left thoracotomy was performed. Due to exten-

sive stickiness of the lung, a resection of the lower left

lobe was needed. After incision of the thoracic aneurysm,

the thrombotic content was removed and major arterial

bleeding occurred, which could be stopped only by clamp-

ing the endoprosthesis. Inspection showed amajor (>2mm)

fabric disruption in the graft material (endoleak type III).

The hole was located in the middle portion of the second

thoracic stent graft at the transition zone with the proxi-

mal bare stent of the third stent graft. This endoleak was

sutured with polypropylene 3/0 reinforced with Teflon

Fig. 3. Transverse CT section through the ninth thoracic

vertebra (venous phase) at 7 months (A) and 21 months

(B) showing increase of the diameter of the descending

aorta and development of erosion of the vertebra.

Vol. 24, No. 4, 2010 Cas cliniques 600.e7

patches and spouted with a fibrin glue (Tissucol�; Baxter,

Vienna, Austria). It was felt safer to try to reline the ori-

ginal stent graft with a new stent graft. However, it was

impossible to introduce a new stent graft, either by a left or

a right femoral approach, due to severe tortuosity and loss

of flexibility at the transition zone with the abdominal

stent graft.

Two days later, the patient developed acute thoracic

hemorrhage with hemodynamic shock. The patient was

intubated, resuscitated, and immediately brought to the

operating theater, where we made another attempt to

reline the thoracic stent graft. Through a sternotomy, a

10 mm Dacron graft (Gelsoft) was sutured on the ascend-

ing aorta as a conduit for two Talent stent grafts that reli-

ned the previously inserted thoracic stent graft precisely.

After extubation on the sixth postoperative day, para-

paresis with sensibility disturbances extending to the

back and the abdomen was obvious. Magnetic resonance

imaging (MRI) of the spine at 1 month showed no defects

in the spinal cord.MRI of the skull did not reveal an expla-

nation for the neurological defects.

Over the next months, the patient improved through

multidisciplinary revalidation. The sensibility and

strength in both legs improved. At themoment the patient

is able to walk with walkers. The paravertebral pain disap-

peared. Every 6 months a follow-up three-phase helical

CT scan is performed. The last CT showed good position of

the stent grafts without endoleaks and with good vascu-

larization of the viscera. The aneurysmal dilatation of the

descending aorta remained stable at a maximum diameter

of 98 mm.

DISCUSSION

This case drew our attention for three reasons. First,

endoleak type III is a rare type of endoleak, espe-

cially if caused by a fabric tear. Second, how could

that the diagnosis of a type III endoleak be missed

in spite of close follow-up with conventional imag-

ing? Third, why did paraparesis develop after

relining of the thoracic stent graft, although no

additional side branches were sacrificed?

Type III endoleaks occur when there is a structu-

ral failure of the stent graft. This includes stent-graft

fractures, fabric tears, and junctional separations

seen with modular devices. However, due to conti-

nuous improvement of the stent grafts, type III

endoleaks are currently quite unusual. Type III

endoleaks are responsible for 20% of all endoleaks.1

We hypothesize that the fabric tear was caused by

repetitive friction between the fabric of the second

stent graft and the bare stent of the third stent graft.

To our knowledge this is the first case of a type III

endoleak due to a fabric tear in a Valiant stent graft.

For our patient, follow-up was organized with

three-phase helical CT scan and plain X-ray. Helical

CT angiography is a standard method for the post-

procedural assessment of aortic stent grafts.2

However, there is evidence that MRI is superior to

CT angiography at detecting endoleaks, at least for

nitinol stent grafts. The Valiant stent graft we used

consists of a nitinol wire scaffolding attached to a

low-profile polyester monofilament weave and is

suitable for MRI-based surveillance.3 According to

Pitton et al.,4 the sensitivity of endoleak detection in

nitinol stent grafts is 92.9%, 44.0%, 34.8%, and

38.3% for contrast-enhanced MRI, biphasic CT,

600.e8 Cas cliniques Annales de chirurgie vasculaire

uniphasic arterial CT, and uniphasic late CT, res-

pectively. The corresponding negative predictive

values are 91.7%, 58.4%, 54.7%, and 56.1%. A

review by Stavropoulos and Charagundla in 20075

on imaging techniques for the detection and

management of endoleaks after endovascular aortic

aneurysm repair concluded that although CT

angiography is currently the standard imaging

modality for endoleak detection, contrast-enhanced

MRI and ultrasound will continue to have an

expanding role in the future. As in our patient CT

angiography showed an unexplained increase of the

aneurysm diameter, contrast-enhanced MRI could

have been a good supplement to the diagnostic

work-up and could have helped to illuminate the

phenomenon of ‘‘endotension’’ in our patient.

Endotension is defined as a persistent or recur-

rent pressurization of the aneurysm sac following

endovascular repair. Gilling-Smith et al.6 reco-

gnized three types of endotension: grade I (high

flow), grade II (low flow), and grade III (no flow).

They hypothesized that one of the possible expla-

nations for grade III endotension was transmission

of pressure through the thrombus that seals an

endoleak. During surgery in our patient we found

thrombus sealing the type III endoleak as an

explanation for why the endoleak was not visuali-

zed on consecutive CT scans. However, as pressure

was transmitted through this thrombus, the aneu-

rysm diameter started increasing after an initial

tendency to shrink.

Spinal cord injury is the most dreaded complica-

tion of repair of descending thoracic and thoracoab-

dominal aneurysms and is often explained by

sacrifice of critical intercostal and lumbar arteries.

The incidence of paraplegia/paraparesis after thora-

cic stent-graft procedures as reported in the litera-

ture varies between 1.5% and 8.7%, the most

important risk factor being the length of the covered

aorta.7-9 However, our patient did not develop

paraplegia after the first intervention, although all

intercostal and lumbar arteries had been covered at

that moment, but 2 years later during relining of an

existing stent graft without sacrifice of additional

arteries. According to the literature, delayed-onset

paraplegia hours or even weeks postoperatively

accounts for up to one-third of cases of post-

operative permanent spinal cord injury.10

To study potential explanations for this phenome-

non, Etz et al.11 retrospectively looked at 10 cases of

paraplegia that developed within 48 hr after surgical

intervention despite intact somatosensory evoked

potentials throughout the operation and compared

them with 10 matched control patients who reco-

veredwithout spinal cord injury. They hypothesized

that differences in postoperative management dis-

tinguished those patients who subsequently had

paraplegia from those who recovered seemingly

normal function and that paraplegia can be caused

byminor differences in postoperative hemodynamic

andfluidmanagement. Notice that the indication for

semiurgent relining of the thoracic stent graft was

hemodynamic and respiratory instability.

That even quite subtle changes in blood pressure

can affect the development of spinal cord injury fits

in the collateral circulation concept as synthesized

by Griepp and Griepp12 and based on many labo-

ratory studies as well as clinical experience.9,13,14

After surgical sacrifice of segmental arteries, perfu-

sion of the spinal cord depends on the stabilization

of a collateral network fed from below by the

hypogastric arteries and from above by the internal

thoracic artery and other branches from the sub-

clavian arteries. This explains why routine sacrifice

of segmental aortic branches can be justified in

surgical and endovascular therapy, without risking

postoperative neurological damage. On the other

hand, the inflow of such a collateral network is very

precarious and depends principally on arterial

pressure, which is largely determined by cardiac

output, blood volume, and the competing demands

of viscera and muscle tissue connected to the same

collateral network. This concept is also supported

by the findings of Buth et al.9 that perioperative

paraplegia or paraparesis is significantly associated

with blockage of the left subclavian artery without

revascularization.

In our patient the first stent graft started distal of

the truncus brachiocephalicus and ended on the

level of the capping of thoracic vertebra 12. The

second one relined precisely the first one without

sacrificing extra vessels. We hypothesize that with

the placement of the first stent graft, the sacrifice

of segmental arteries was compensated for by the

collateral network and no neurological disturbances

occurred. However, hemodynamic instability pre-

ceding the relining procedure disturbed this preca-

rious balance in blood supply to the spinal cord.

The absence of neurological disturbances after a tho-

racic stent-graft procedure therefore does not abso-

lutely exclude the possibility of spinal cord ischemia

during relining of the same stent graft.

Perfusion-weighted MRI has been used increa-

singly in the investigation of acute cerebral

infarcts.15 Unfortunately, there are few reports of

the spinal cord. However, Yanaka et al.16 demons-

trated vasogenic edema of the spinal cord using

perfusion-weighted MRI. We suggest that transient

hypoperfusion of the spinal cord can create vaso-

genic edema, which can resolve once the circulation

Vol. 24, No. 4, 2010 Cas cliniques 600.e9

has restored itself. This would explain why the

paraparesis was transient.

There are several studies suggesting techniques to

reduce the chances of spinal cord ischemia. Jacobs

and Mess17 described in 2003 that the combination

of monitoring motor-evoked potentials, cere-

brospinal fluid drainage, distal aortic perfusion, and

epidural cooling could prevent neurological deficit

in 98% of patients with open thoracoabdominal

aortic aneurysm repair. They confirmed this in an

extensive study in 2006.18 Rigorous perioperative

hemodynamic and fluid management could help to

overcome delayed-onset paraplegia.11 Aware of

these findings, we always use prophylactic cere-

brospinal fluid drainage when covering the distal

third of the descending aorta. However, in this

patient we did not as we wrongly felt that a simple

relining of the graft would have no consequences on

the medullar circulation.

In conclusion, a fabric tear resulting in a type III

endoleak can happen. In patients with unexplained

increase of the aneurysmal sac, contrast-enhanced

MRI could help to illuminate the underlying endo-

leak. The collateral network concept can explain

spinal cord injury by even minor hemodynamic

changes.

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