Keywords
aortic dissection - TEVAR - aortic pain - acute aortic syndrome - candy plug - spinal
cord protection - visceral perfusion
Introduction
Aortic dissection is a painful and dangerous condition leading to urgent medical and
surgical treatment. False lumen perfusion remains one of the unmet needs after thoracic
endovascular aortic repair (TEVAR) and further procedures aim to complete the result.
Candy plug technique has been recently introduced as an ancillary operation during
TEVAR for Type B aortic dissection.[1]
[2]
Complications are described as the possibility of vessel wall injury caused by continuous
shear stress from the plug.[3] Despite the presence of adverse events related to possible mechanical lesions, the
review of the literature lacks chronic pain after “candy plug.”[4]
[5]
Case Presentation
Our experience reports the case of a 41-year-old male patient who presented to our
outpatient department for severe back pain. The patient had been emergently treated
with a zone-2 TEVAR with distal PETTICOAT (provisional extension to induce complete
attachment) limited to the thoracic region for complicated Type-IIIB aortic dissection
performed due to a worsening of pleural effusion and to a not responding arterial
hypertensive state. The left subclavian artery was neither revascularized nor occluded
at the origin. The intervention was complicated by left cerebral ischemia; the stroke
resulted in a right hemisyndrome with mild walking impairment. Patient followed a
neurological rehabilitation program both in hospital and after discharge. A 2-month
computed tomography (CT) scan observed a Type-IC endoleak and complete reperfusion
of the false lumen from distal reentry tear with enlargement of the false lumen associated
with intermittent pain. The subsequent treatment entailed a stent–graft extension
from the previous TEVAR to just above the celiac trunk origin followed, 2 weeks after,
by embolization of the origin of the left subclavian artery and occlusion of the distal
false lumen with a candy plug version II.[2]
[3] The immediate postoperative course was characterized by a postimplant syndrome treated
with steroids. Nonetheless, a few months after these procedures, the patient returned
with worsening back pain that was hardly responding to any common pain killers. Repeated
hospitalizations and complete vascular and neurological evaluations did not show any
technical and anatomical issues to justify the recurrent pain. Follow-up CT scans,
performed to rule out an aortic etiology of the pain, revealed a progressive complete
thrombosis of the false lumen with progressive shrinkage of its portion in the thoracic
region and stable transaortic diameter in the abdominal region with the residual dissection
(46 mm; [Fig. 1]). The patient was referred for algological therapy with a mild regression of the
visual analogue scale (VAS) from 8 to 6. After 18 months, since the first procedure,
the patient was under transdermal oxycodone treatment. A Short Form 12 Health Survey
Scale (SF-12) was administered underlying severe physical and social impairment because
of back pain and drug therapy. During a new hospitalization, in our hospital, new
angio-magnetic resonance imaging (MRI), electroencephalogram, electroneuromyography,
and somatosensorial-evoked response tests excluded any neurologic defects. Lung and
pleural evaluations showed normal results. In the end, despite the technical success,
the aortic nature of the pain was suspected and zooming the bulk of endovascular material
inside the thoracic aorta as a trigger for complex regional pain syndrome (CRPS).[4]
[5] Therefore, the candy plug removal was considered to reduce the radial force working
inside the aorta. The patient was approached in two stages. First, a left carotid
subclavian artery bypass was performed to increase the collateral network inflow considering
that preoperative MRI and CT scan failed to detect patent intercostal arteries arising
from the stent–grafted region. Ten days after cervical bypass, a semiconservative
open conversion was performed through a left thoracoabdominal incision in the eighth
intercostal space; the progressive shrinkage of the thoracic false lumen allowed treating
the patient as a Type-IV thoracoabdominal aortic aneurysm (TAAA). Cerebrospinal fluid
drainage and permissive hypothermia (lower rectal temperature of 33°C) combined with
the previous left subclavian artery revascularization were employed as adjuncts for
spinal cord protection. The thoracoabdominal aorta was prepared from approximately
10 cm above the aortic hiatus down to the aortoiliac bifurcation. Before opening the
aorta, the region where “candy plug” imprinting the aortic adventitia was evident
([Video 1]; available in the online version). “Candy plug” bulged out from the aortic false
lumen through a 10-cm long longitudinal incision ([Video 1]; available in the online version). After aortic cross-clamping, the false lumen
was longitudinally opened, the candy plug was removed ([Fig. 2]), and the true lumen endograft was partially resected to both perform the proximal
anastomosis in a dissection-healed thoracic region and resect the residual and aneurysmal
abdominal aorta. Visceral and renal protection was obtained with local hypothermic
perfusion with 4°C Mannitol and Ringer Lactate solution.[2]
[3] Proximal aortic graft was sutured end to end with the endograft and distally a beveled
anastomosis, including visceral and renal vessels, was performed.[3] Recovery was uneventful, and patient was discharged on postoperative day 15. After
4 months, the patient reported VAS 2 with no need of opiates as painkiller.
Fig. 1 Computed tomography (CT) post- thoracic endovascular aortic repair and “candy plug”
CT scan showing effective resolution of Type B aortic dissection.
Video 1 Reporting the surgical approach, candy plug removal, cold renal and visceral perfusion,
and result.
Fig. 2 Candy plug after removal. To note, the whole device caliber and the forceps.
Discussion
Chronic pain is an abnormal process due to pain response to the activation of fibers
for innocuous stimuli. It is characterized by three processes in the spinal cord accounting
for alteration in the somatosensory system, that is, increased excitability, decreased
inhibition, and structural reorganization. Their concurrent contribution could lead
to CRPS.[4]
[5] Except for acute aortic syndrome, thoracic aorta is not usually considered as a
pain-producing organ. The occurrence of pain during balloon inflation for aortic coarctation
or TEVAR, which disappears immediately after deflation, is related to the activation
of the orthosympathetic nervous system. When the nervous fibers are triggered, patients
experience tachycardia, profuse sweating, and VAS > 8. As soon as the triggering event
fades away, the relief for the patient is immediate. Aortic pain is usually associated
with dissection and high pressure in the false lumen. Successful exclusion of the
false lumen in chronic dissection remains a challenge. Survival is associated with
aortic remodeling which is related to the persistence of flow in the false lumen.
In literature, a few articles concern candy plug and its application in modern endovascular
therapy.[6] The most important search engines related to scientific publications have no more
than 30 articles about this topic. We did not find case reports of conversion into
open surgery and any complications that arise with the procedure can be treated by
conservative therapy or adjunctive endovascular treatment. No pain induced or postimplantation
syndromes are related to candy plug. Meanwhile, systemic effects, as a noninfectious
fever, elevated C-reactive protein, leukocytosis, and coagulation disturbances are
discussed, and ascribed to proinflammatory mediators, description of local effects
is missing.[1] One of the considerations about vascular pain is the postoperative modification
of sympathetic nervous system with changes in vascular reactivity and morphology leading
to CRPS.
Literature has a lack of models of pain after candy-plug insertion, and assumptions
are made on basic physiology. Angioplasty procedures could account for pain during
the balloon inflation disappearing after deflation. We supposed the delivery of the
candy plug associated with the space occupied by the previous endoprosthesis stretched
the vessel wall in a chronic pattern. Decision-making was challenging. Patient compliance
with pain was very low and functional impairment was practically complete. The aortic
stress on the vessel wall was the only option left for neuropathic pain leading us
to open treatment. The patient, whom we decided to treat, developed an invalidating
CRPS. Open surgery showed how the adventitia layer was under additional stress because
of the bulk of the candy plug. As we expected, the pain diminished after the surgery
steadily and now the patient is free from painkillers. Complementary lyses of nerve
endings during vessel isolation could have shut down the pain loop as it proved in
sympathectomy procedures.[7]
[8]
