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The “bare branch” for safe spinal cord ischemia prevention after total endovascular repair of thoracoabdominal aneurysms
From the Society for Vascular Surgery
The “bare branch” for safe spinal cord ischemia prevention after total endovascular repair of thoracoabdominal aneurysms Matteo Orrico, MD,a Sonia Ronchey, MD, PhD,a Carlo Setacci, MD,b Alessio Vona, MD,a Mario Marino, MD,a Fabrizio Nesi, MD,a Alessia Giaquinta, MD,a and Nicola Mangialardi, MD,a Rome and Siena, Italy
ABSTRACT Objective: Staged endovascular treatment of thoracoabdominal aortic aneurysms (TAAAs) with temporary perfusion of the sac through a branch left unstented or a dedicated branch is a strategy intended to reduce the risk of postoperative spinal cord ischemia (SCI). However, potential complications of this approach are aneurysm sac progression between stages, visceral embolism, and occlusion or displacement of components. We here present the “bare branch” technique, a safe adjunct to TAAA repair in terms of interstage complications. Methods: In the first step, one branch, preferentially the one for the celiac trunk, is stented by a bare stent; in the second step, the bare branch is relined with a covered stent. There were 32 TAAAs (5 type I, 6 type II, 16 type III, 5 type IV) treated by this approach at our center from January 2015 to December 2017 (median follow-up, 13 months [range, 2-24 months]). Data were prospectively collected and retrospectively analyzed. Primary end points were aneurysm sac exclusion and freedom from major adverse events, which included SCI. Secondary end points were freedom from aneurysm growth between the stages and freedom from minor adverse events. Results: Preoperative mean maximum diameter was 68.4 mm; 32 endografts (8 off-the-shelf and 24 custom-made devices) were used. The mean aortic coverage was 364 mm. The mean interval time between the two stages was 10.5 weeks (range, 7-20 weeks). In-hospital mortality was 0%. Type I or type III endoleak rate was 3.2%, whereas one type II endoleak was registered (3.2%). Two patients showed paraparesis, one after the first stage and one after the second stage, both noted at 4/5 on the Tarlov scale, and fully recovered so that the SCI rate was 6.4% with 0% permanent neurologic deficit. Interstage mean maximum diameter was 68.6 mm (P > .05). After the second step, there was an average of 4.7 spinal arteries (standard deviation, 1.4; P < .05) per patient with an increase in visibility and of diameter by 0.7 mm (standard deviation, 0.4 mm). Conclusions: This is a reproducible adjunct to staged TAAA endovascular repair. The use of a bare branch instead of a branch left completely open has the clear advantage of an easy catheterization in the second step. Furthermore, by having the target vessel stented with a bare stent, the risk of embolism is avoided. In this experience, there was no significant aneurysm sac growth in between the steps. Further comparative studies may determine whether there are different hemodynamic forces with this technique with respect to those already described in the literature. (J Vasc Surg 2018;-:1-9.) Keywords: Thoracoabdominal aortic aneurysm; BEVAR; FEVAR; Paraplegia; Spinal cord ischemia
Open repair is still considered the “gold standard” of thoracoabdominal aortic aneurysm (TAAA) treatment, with good results in high-volume centers, especially in
From the Department of Vascular Surgery, San Camillo Forlanini Hospital, Romea; and the Department of Vascular Surgery, University Hospital of Siena, Siena.b Author conflict of interest: none. Presented in the International Forum at the 2018 Vascular Annual Meeting of the Society for Vascular Surgery, Boston, Mass, June 20-23, 2018. Correspondence: Matteo Orrico, MD, Vascular Surgery Department, San Camillo Forlanini Hospital, Circonvallazione Gianicolense 87, 00152 Rome, Italy (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2018 by the Society for Vascular Surgery. Published by Elsevier Inc. https://doi.org/10.1016/j.jvs.2018.09.027
young patients.1 Nevertheless, fenestrated and branched endovascular aneurysm repair by custom-made or off-the-shelf devices (t-Branch; Cook Medical, Bloomington, Ind) has promising results in terms of mortality and morbidity, now confirmed by long-term follow-up.2,3 However, spinal cord ischemia (SCI) due to an extensive aortic coverage, with a frequency ranging from 0% to 31%,4,5 is a potentially disastrous complication that dramatically affects both the physical and psychological aspects of the postoperative life of the patient. Several approaches have been proposed to minimize the risk of paraplegia, such as motor evoked potential monitoring, controlled mean arterial pressure, cerebrospinal fluid drainage (CFD), and staged repair.6,7 Staged repair in particular has the aim of enhancing the collateral network supplying the spinal cord by a gradual exclusion of the aneurysm and by the following gradual and relative spinal cord hypoxia, which 1
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stimulates neoangiogenesis.7,8 The technical adjunct of an aneurysm sac “perfusion branch” was initially described in a case report and subsequently in case series. In a first step, the aortic component is deployed and the aneurysm sac is kept perfused by one or more visceral branches left open or, rarely, by a branch dedicated to temporary aneurysm sac perfusion (TASP). Eventually, in the second step, the visceral arteries are stented by the bridging stents, and the repair is completed.6,7,9 Despite the good results in terms of decreased SCI, some concerns about this approach arise from the substantial aneurysm growth rate after long interstage time, probably because of a high-flow input to the sac through the branch left completely open without an outflow. Another issue that has been highlighted with such an approach is the theoretical risk of open branch occlusion in particular conditions (ie, compression).7 Furthermore, the ongoing thrombosis of the aneurysmal aorta is theoretically accompanied by a certain risk of embolic complications, which can involve the unstented visceral vessels. The objective of the study was to investigate the results of the “bare branch” repair as a valid staged alternative to the classic perfusion branch.
METHODS This study conforms to the Declaration of Helsinki. Informed consent was collected from every patient. Eligibility and selection of patients From January 2015, the bare branch technique was used at our center for every TAAA that we intended to treat by an aortic endograft having at least one branch. Exclusion criteria were emergency/urgency setting because of the risk of keeping an unstable sac (either ruptured or symptomatic) temporarily perfused and thoracic aortic aneurysm treated with endografts having only fenestrations. Until December 2017, there were 32 patients with a TAAA (5 type I, 6 type II, 16 type III, and 5 type IV Crawford extent aneurysms) treated by this approach. Data were prospectively collected in an institutional database and retrospectively reviewed. Primary end points were aneurysm sac exclusion and freedom from major adverse events, which included SCI. Secondary end points were freedom from aneurysm growth between the stages and freedom from minor adverse events. Imaging preoperative study and follow-up Contrast-enhanced computed tomography angiography (CTA; slice thickness #0.5 mm) was always performed preoperatively. The mean period between preoperative CTA acquisition and the first stage was 3.5 months (mean, 2.8 months; range, 1.5-3.5 months). A second CTA scan was always scheduled and acquired 1 to 2 weeks before the second stage and
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ARTICLE HIGHLIGHTS d
d
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Type of Research: Retrospective single-center cohort study of prospectively collected data Take Home Message: Staged branched endovascular repair of 32 thoracoabdominal aortic aneurysms using a bare stent for temporary aneurysm sac perfusion prevented permanent spinal cord ischemia in all patients, with no mortality. Recommendation: The use of a bare branch in patients who undergo branched endovascular aneurysm repair appears to decrease paraplegia and mortality. It has the advantage of easy catheterization in the second step and no risk of embolization.
never <6 weeks after the preceding step. All patients underwent a postoperative CTA control scan 30 days after the second step and yearly thereafter. A contrastenhanced ultrasound examination was performed 6 months after the second step and then yearly (Fig 1). All the CTA examinations were independently reviewed and analyzed by two investigators (M.O. and S.R.) using the same postprocessing software (Aquarius; TeraRecon, San Mateo, Calif). A priori “acceptable” differences for the interobserver variability were set for each measurement as follows: 3.0 mm for aortic diameter measurements; 0.5 mm for diameter of lumbar and intercostal arteries; and 15% for number of lumbar and intercostal arteries. These values were chosen on the basis of clinical expert opinion of the vascular surgeons involved in the study supported by literature reports of aortic CTA measurements.10-13 For these parameters, an interobserver Lin concordance correlation coefficient (LCCC) was used to determine interobserver agreement based on these differences with the a value being set to .05 (95% confidence interval). An LCCC <0.90 signified poor agreement, 0.90 to 0.95 was moderate, 0.95 to 0.99 was substantial, and >0.99 indicated almost perfect agreement. All statistical analyses were performed using SPSS statistical software (version 22.0; IBM Corp, Armonk, NY). SCI preventive measures Further preventive measures were always taken in both stages. Mean arterial pressure was always kept $80 mm Hg intraoperatively and for the subsequent 72 hours after both the first and second stages. Routine prophylactic CFD was used for every patient in both steps, except for the five type IV TAAAs, in which CFD was used only for the second step. CFD was always retained for 48 hours postoperatively in the absence of complications with a target cerebrospinal fluid pressure of 10 mm Hg. Neurologic evaluation was invariably performed by the same neurologist and expressed on the Tarlov scale whenever an impairment was evident or suspected and then repeated every day for the first 3 days and every 3 days until discharge.14
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Fig 1. Computed tomography angiography (CTA) volume rendering through the stages. A, Preoperative CTA of a type II thoracoabdominal aortic aneurysm (TAAA). B, CTA before the second step. The aneurysm sac is perfused through the bare branch positioned in the celiac trunk; two new segmental arteries are visible (arrow). C, CTA at 30 days after the bare branch relining.
Technique First step. In the first step, under general anesthesia, the main graft is deployed. From a femoral access, all fenestrations and respective target vessels are catheterized and connected by bridging covered stents. From a brachial access, all branches but one, preferentially the celiac trunk branch, are also catheterized and connected to the respective visceral vessels by bridging covered stents. Finally, the last branch is catheterized and connected to the last target vessel with a bare stent. Angiography confirms the presence of the intentional endoleak (Fig 2). Second step. The second step is performed a minimum of 6 weeks after the first step. Under local anesthesia and systemic heparinization, through a percutaneous brachial access (maximum 8F), the bare branch is catheterized. A noncompliant balloon is inflated for the whole length of the bare branch to simulate exclusion of the aneurysm sac, which is assessed by angiography; the balloon is then kept to nominal pressure for 20 minutes while the patient is monitored. In cases in which the patient would show any neurologic lower limb impairment, the bare stent relining is postponed. If there is no leg strength or sensibility impairment, the bare branch is relined with a covered stent. Final angiography confirms the aneurysm sac exclusion (Fig 3).
RESULTS There were 32 patients with a mean age of 69.9 years (standard deviation [SD], 19.9 years; range, 50-82 years) treated by the bare branch technique; demographics are summarized in Table I. The majority were type III TAAA patients. The preoperative mean aneurysm sac diameter was 68.4 mm (SD, 8.4 mm; range, 60-78 mm); 21 patients were treated with custom Cook endografts, 8 patients were treated with t-Branch (Cook), and 3 patients were treated with custom TAAA devices
Fig 2. Completion angiogram of the first step in a postdissection thoracoabdominal aortic aneurysm (TAAA) in a patient with Marfan syndrome. The sac is perfused through a bare stent in the celiac trunk. This is the only case in which a proximal covered stent (Bentley BeGraft) was deployed as a bridging stent for the bare branch and the main module. This choice was taken because initially the branch dedicated to the celiac trunk was slightly compressed by the lamella, so a stent with high radial force was chosen.
(JOTEC, Hechingen, Germany), accounting for a total of 123 target vessels with an average number of 3.84 visceral vessels per patient. First-step features. The mean duration of the first step was 3.2 hours (SD, 0.7 hours; range, 2.5-5.0 hours), and it was always performed under general anesthesia. The perioperative patency rate was 99.2%. In one case, we were not able to catheterize the celiac trunk from an upper access, so the dedicated inner branch was closed with a plug; and in the same session and from a femoral
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Fig 3. Second-step angiograms in a renal bare branch patient. A, The initial angiogram confirms perfusion of the aneurysm sac through the bare stent struts. B, An angiogram obtained once a balloon is inflated to confirm the effective reversible 20-minute sac exclusion and for neurologic testing. C, Second-step completion angiogram. The bare branch is relined with a covered stent, and the sac is finally excluded.
Table I. Demographics of bare branch population Demographics
% (No.)
Male
75 (24)
Hypertension
87 (28)
Smoke
66 (21)
Ischemic cardiomyopathy
53 (17)
Dyslipidemia
78 (25)
Chronic obstructive pulmonary disease
44 (14)
Diabetes
25 (8)
Renal failure Mild Severe, dialysis Connective tissue disease, Marfan syndrome ASA class 3-4 Prior vascular interventions
Monolateral chronic hypogastric occlusion
22 (7) 3 (1) 3 (1) 75 (24) 9 (3; 1 Bentall procedure, 1 frozen elephant trunk, 1 EVAR) 6 (2)
Crawford aneurysm extent I
16 (5)
II
18 (6)
III IV
50 (16, 1 postdissection aneurysm) 16 (5)
ASA, American Society of Anesthesiologists; EVAR, endovascular aneurysm repair.
access, the celiac trunk was coil embolized. In this patient as well as in another one treated by a Cook custom graft with only two branches (one for a common celiac-mesenteric trunk and one for a right renal artery; the left renal artery was aneurysmatic and chronically thrombosed), the bare branch target vessel was a renal
artery, so that the target bare branch was the celiac trunk in 93.7% of cases and a renal artery in 6.3% of cases. In these patients, serum creatinine levels were normal enough to allow a safe 20-minute warm ischemia under systemic heparinization, and they showed no postoperative serum creatinine level increase. The mean aortic coverage was 364 mm (SD, 110 mm; range, 250-490 mm), and the mean supraceliac coverage was 230 mm (SD, 95 mm; range, 135-270 mm). For the bare branch, the Protégé (Medtronic, Santa Rosa, Calif) was used in all the patients; the overall number of stents used in the first procedure was 159 (22 Fluency Plus [Bard Peripheral Vascular, Tempe, Ariz]; 74 BeGraft Peripheral [Bentley Innomed, Hechingen, Germany]; and 62 Advanta V12 [Atrium Europe B.V., Mijdrecht, The Netherlands]). The median hospital stay after the first intervention was 12.9 days (range, 7-23 days). No major in-hospital complications occurred after the first procedure with the exception of a paraparesis, noted at 4/5 according to the Tarlov scale; this occurred in a 78-year-old woman with a history of endovascular aneurysm repair (with a suprarenal fixation endograft) 5 years before. Her history was also positive for a Bentall procedure for an ascending aortic aneurysm 1 year before as well as for ischemic cardiomyopathy and hypertension. She came to our attention with a type III TAAA and patent hypogastric arteries; a repair was planned with a custom Cook graft with one fenestration for her sole renal artery and two branches for the superior mesenteric artery and celiac trunk. The procedure was uneventful, but right after the patient was readmitted to the service from the intensive care unit on the first postoperative day, with spinal drainage still installed, she experienced lack of leg strength bilaterally and needed crutches to walk; sphincters were unharmed. A highdose methylprednisone protocol, with a bolus of 30 mg/kg and 5.4 mg/kg/h for the subsequent 48 hours, was administered; the drainage was kept in place for
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Table II. Relevant computed tomography angiography (CTA) findings preoperatively, between the two steps, and 1 month after the second step Preoperative CTA
Interstage CTA (mean interval after CTA 1 month after the first step, 20.2 weeks) the second step
P value, ANOVA test for repeated measures
Aneurysm maximum diameter, mm
68.4
68.6
68.6
.363
Segmental arteries along the aorta
19.3
14.4
12.5
.002
Average diameter of segmental artery visible in the first and second CTA scans (thrombosed after the second CTA scan), mm
2.1
2.3
e
.004
Average diameter of segmental arteries visible in all three CTA scans, mm
1.7
1.9
1.9
.004
ANOVA, Analysis of variance. Of note, the aneurysm diameter did not show a significant increase despite the long waiting time between the two steps. The counted spinal arteries along the aorta showed a significant increase in diameter.
48 hours, with a target pressure of 10 mm Hg (a slight hypertension of 17 mm Hg was noted initially but was transient and easily manageable with drainage). On the third postoperative day, her symptoms regressed completely. The minor complication rate was 6.4%. We registered one brachial hematoma, which required a revision, and one mild alteration of renal function (serum creatinine level increase by 40%). Second-step features. The second step was performed at an average time of 10.5 weeks (SD, 3.5 weeks; range, 7-20 weeks) after the first step. In the time between the two stages, no vessel or bare branch occlusions were registered, and there were no unplanned hospital admissions. This step was always performed under local anesthesia and in 97% of the cases from a brachial access. The access was femoral in only one case (3.1%) for the patient described before, treated with a JOTEC custom-made device, in which the bare branch to be relined was in an upward inner branch for the left renal artery. The mean access size was 7.25F (SD, 1.25F; range, 6F-9F). As the noncompliant balloon for simulation of aneurysm sac exclusion and neurologic clinical intraoperative testing, we always used a Mustang balloon (Boston Scientific, Marlborough, Mass), and it was always of the same nominal diameter as the bare branch. Suspension of the procedure was never necessary as no neurologic lower limb impairments were noted at the 20-minute evaluation. In 87.1% of cases, the covered stent used was the Fluency Plus; in the remaining 12.9% of cases, it was a BeGraft. Closure was always obtained by manual compression. The mean duration of the second step was 39.1 minutes (SD, 8 minutes; range, 31-72 minutes). No major complications were registered after this step, and like after the first step, one paraparesis at 4/5 on the Tarlov scale was registered, in this case on the second postoperative day. This occurred in a 75-year-old male
diabetic with ischemic cardiomyopathy who presented with a type II TAAA and patent hypogastric arteries. He was treated in a first stage with a t-Branch overlapped with two proximal thoracic modules. Following removal of the CFD after bare branch relining, he experienced a mild walking impairment with reduced leg strength bilaterally. The CFD was replaced and kept for 48 hours with a target pressure of 10 mm Hg, and the high-dose methylprednisone protocol was started (see before, first-step features). The symptoms fully regressed after 3 days. No complications relative to the second puncture of the CFD were registered. Patients were discharged after an average hospitalization time of 3.3 days (SD, 1.3 days; range, 2-5 days) following the procedure. Postoperative follow-up. The median postoperative follow-up was 13 months (range, 2-24 months). No aneurysm-related mortality was registered during this period; two deaths were registered at 15 and 20 months, one for a lung adenocarcinoma and one for an acute myocardial infarction. No neurologic events were noted after the discharge. No target vessel or branch occlusions were registered at median follow-up. One (3.2%) type II endoleak was evident after the 30-day CTA examination and is currently under surveillance; it has not shown evidence of growth so far. Another endoleak (3.2%) appeared on the 1-year CTA control scan and was due to a first-generation BeGraft fracture on the celiac trunk branch. It was promptly relined with a BeGraft Plus, so that the reintervention rate was 3.2%. CTA analysis. CTA relevant findings are summarized in Table II. The mean maximum aortic preoperative diameter was 68.4 mm (SD, 8.6 mm; LCCC, 0.97); the mean diameter at interstage CTA was 68.6 mm (SD, 7.6, mm; LCCC, 0.97). They were not significantly different at the analysis of variance (ANOVA) test for repeated measures (P ¼ .363; Fig 4). The second CTA study was
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DISCUSSION
Fig 4. Box plot graphically showing the results of the analysis of variance (ANOVA) test for preoperative and postoperative aneurysm sac maximum diameter. Despite a long interstage time, no significant aneurysm growth was evident. CTA, Computed tomography angiography.
performed at an average time of 20.2 weeks (SD, 11 weeks; range, 9-28 weeks) from the first one and at 1.2 weeks (SD, 0.8 weeks; range, 1-2 weeks) before the bare branch closure. The 1-month postoperative diameter (68.6 mm; SD, 31 mm; LCCC, 0.97) was not significantly different (P > .05). Twenty-one (66%) patients completed the 1-year follow-up, and in this subgroup there was a significant shrinkage of the aneurysm sac (70.2 mm vs 63.6 mm; P < .05). The segmental arteries along the aorta were 19.3 preoperatively and 14.4 between stages; 12.5 remained visible after the second step (P < .05; LCCC, 0.97, 0.97, 0.96, respectively). On analyzing the uncovered segmental artery group between the first and second steps, an average of 4.7 of them (SD, 1.3; range, 3-5; P < .05; LCCC, 0.96) showed an increase in visibility and by 0.7 mm in diameter (SD, 0.4 mm; Figs 5 and 6). The mean diameter of the subgroup of spinal arteries that were visible until the second step was 2.1 mm (SD, 0.4 mm; range, 1.0-2.5 mm) on preoperative CTA and 2.3 mm (SD, 0.4 mm; range, 1.0-2.7 mm) on the interstage CTA (ANOVA test for repeated measures, P < .02). The mean diameter of the subgroup of spinal arteries that remained visible after the second stage also increased significantly on comparing the preoperative diameter with the final result. At any rate, there was no significant difference between their average diameter on interstage CTA vs 1-month CTA (1.7 mm [SD, 0.5 mm]; 1.9 mm [SD, 0.4 mm]; 1.9 mm [SD, 0.4 mm]; Fig 7; ANOVA test for repeated measures, P < .05 for the three CTAs; ANOVA test for repeated measures, P ¼ .168 for the interstage vs 1-month CTA).
SCI, which can lead to paraplegia, is a potentially devastating complication that still negatively affects the outcomes of both open and endovascular treatment of TAAAs. With regard to fenestrated and branched endovascular repair of TAAA, several SCI preventive measures have been described; but despite those, the incidence of such complication is still high, ranging from 5% to 30% in the latest reports.5,15-17 In a review of preventive strategies used for thoracic and thoracoabdominal repair, Dijkstra et al18 recently reported improved results for both transient and permanent SCI in the last years. However, they also highlighted a lack of evidence on this topic that makes it impossible to create definitive recommendations as to which type of preventive measures to adopt. Perioperative hypotension avoidance or controlled hypertension and permissive temporary endoleak have been reported as valid strategies to lower SCI. For other measures, such as prophylactic CFD and neuromonitoring, the findings are more conflicting. Furthermore, there is no clear association between preventive strategies, alone or in association, and the persistence of SCI, which is however more frequently temporary.18-20 Staged procedures and permissive endoleak have their rationale in the spinal cord preconditioning mechanism. It has been demonstrated that a relative and sustained spinal cord hypoperfusion causes several morphologic changes in its blood supply (enlargement, redistribution, reorientation of the segmental arteries), which are the target of the “minimally invasive segmental artery coil embolization” technique as well as of TASP.7-9,21 TASP, in particular, described by Kasprzak et al in 2014, is accompanied by an SCI rate of 5% and consists of the temporary perfusion of the sac by a branch left completely open, dedicated to either a renovisceral vessel or the TASP itself.7-9 In the TASP experience, even with good results in terms of SCI, some drawbacks are evident. Primarily, aneurysm sac progression is relevant, being as high as 26% for interstage periods >4 weeks and 12.5% on the 48-day mean interstage time of the overall experience. This is probably due to a high-flow input to the aneurysm sac through the branch left completely open, without an outflow. The mortality rate between the two steps is also not negligible; the aneurysm-related mortality is 12.5% (one case of aneurysm rupture). Another concern with this technique is the potential risk of component disconnection and misalignment and even occlusion that may arise from the lack of support with not having all the target vessels stented; for the technique, one failure of recatheterization is reported. Finally, the progressive aneurysm sac thrombosis, which is intended to enhance the spinal cord supply, may, on the other hand, involve unstented vessel ostia with a consequent risk of occlusion. The
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Fig 5. Favorable changes of a segmental artery are evident at computed tomography angiography (CTA) through the stages. A, Preoperative CTA. B, On CTA before the second step, the segmental artery shows a 0.5-mm increase in diameter. C, On final CTA, the diameter of the segmental artery has a slight new increase.
Fig 6. Favorable changes of median sacral artery (indicated by the red arrow) on computed tomography angiography (CTA) through the stages. A, Preoperative CTA. B, On CTA before the second step, the median sacral artery is more evident. C, On final CTA, the median sacral artery gains further visibility.
authors sustain the hypothesis that the TASP approach may have better results once there will be a way to control the blood flow through the branch. We already described our “open branch” method in a three-case experience in 2015. We reported a successful two-step exclusion of three TAAAs, with two of them leaving the sac perfused by a bridging bare stent in the celiac trunk and with one through a bare stent placed instead of an iliac limb.22 In this current experience, which does not include those three cases previously reported, we describe our results of a larger cohort treated homogeneously as we standardized our approach after those three cases. With the bare branch, we aim to offer a safe alternative to the already described TASP. There are three main reasons that we preferentially use the celiac trunk as a target for the bare branch. First, it is the most proximal of the vessels to stent in TAAA repair
and so the closest to the “critical” zone in speaking about spinal cord vascularization. Furthermore, access to the celiac trunk is usually more straightforward than to other branches, and it is less frequently involved in abdominal tortuosity and therefore easier to catheterize in the second step. Finally, the parenchyma vascularized by the celiac trunk is more resistant to the endoclamping that will be done in the second step in comparison to the kidneys, for example. After our observations in the experience with the first three patients,22 in which no sac growth was evident, we considered 6 weeks the minimum interval at which to schedule the second procedure. We wanted a safe waiting time, long enough to develop a collateral spinal cord vascularization. The long time between the steps is principally due to the availability of patients to be hospitalized for a second step; this is a pitfall to consider as patients generally think of this second intervention as
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step; on the contrary, we found the second step very easy, primarily because of the previously implanted bare stent. The long interval time in the absence of significant major adverse events with an SCI rate in line with reported rates shows that this method is a safe and reproducible adjunct to the staged repair of TAAAs.
CONCLUSIONS
Fig 7. Box plot graphically showing the results of the analysis of variance (ANOVA) test for the mean diameter of the segmental arteries that are evident on preoperative, interstage, and 30-day computed tomography angiography (CTA). An increase in diameter is evident through the stages.
a minor procedure and need to be urged more than once before they call themselves ready to undergo this second step. CTA performed just before the second step always showed a partial sac thrombosis. Our SCI rate is 6.4% and 9% if only type I and type II TAAAs are considered, which is comparable with the current literature reports, with 0% of permanent deficit. As for reinterventions, we report one case of stent fracture. Initially, we hypothesized that this may have resulted from an unfavorable materials interaction between the BeGraft deployed in the second step and the surrounding bare stent deployed in the first step. However, we subsequently noticed that the fractured stent was part of a BeGraft generation for which a high rate of fractures was noted, mostly when they were used for branch configurations. Noteworthy, however, is the fact that despite a time between the two procedures that was longer than the average time reported in the literature, we did not register any relevant aneurysm sac progression. However, in line with the previous literature findings, we did notice some relevant morphologic CTA changes in the spinal cord vascularization, such as the increase in diameter of the uncovered segmental arteries.6,7 An advantage of the bare branch derives from the fact that using a bare stent instead of a branch left completely open may give one more fixation zone to the complex with a consequent increase in stability, and having all the target vessels and branches stented protects the patients from occlusion. In fact, we did not observe cases of branch or target vessel occlusion and never failed to catheterize the branch in the second
The bare branch appears to be a reproducible and safe adjunct to staged TAAA endovascular repair. It is effective in terms of SCI prevention and has the advantage of an easy completion in the second step and an enhanced protection to the target vessels and ostia between the steps. Unlike what is reported in the literature for other SCI preventive methods, our experience was not accompanied by relevant aneurysm sac growth. Further studies with control groups may highlight whether different hemodynamic forces play a role in this finding. The authors acknowledge Michael Tarullo, Adjunct Professor, School of Science, Monmouth University, Long Branch, NJ, for language revision.
AUTHOR CONTRIBUTIONS Conception and design: MO, SR, CS, NM Analysis and interpretation: MO Data collection: MO, SR, AV, MM, FN, AG Writing the article: MO, NM Critical revision of the article: MO, SR, CS, AV, MM, FN, AG, NM Final approval of the article: MO, SR, CS, AV, MM, FN, AG, NM Statistical analysis: MO Obtained funding: Not applicable Overall responsibility: NM
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conduits to minimize risk of spinal cord injury during complex endovascular aortic repair. J Endovasc Ther 2016;23: 139-49. Kasprzak PM, Gallis K, Cucuruz B, Pfister K, Janotta M, Kopp R. Temporary aneurysm sac perfusion as an adjunct for prevention of spinal cord ischemia after branched endovascular repair of thoracoabdominal aneurysms. Eur J Vasc Endovasc Surg 2014;48:258-65. Etz CD, Kari FA, Mueller CS, Brenner RM, Lin HM, Griepp RB. The collateral network concept: remodeling of the arterial collateral network after experimental segmental artery sacrifice. J Thorac Cardiovasc Surg 2011;141:1029-36. Reilly LM, Chuter TA. Reversal of fortune: induced endoleak to resolve neurological deficit after endovascular repair of thoracoabdominal aortic aneurysm. J Endovasc Ther 2010;17:21-9. Lin LI. A concordance correlation coefficient to evaluate reproducibility. Biometrics 1989;45:255-68. Lin LI. A note on the concordance correlation coefficient. Biometrics 2000;56:324-5. Singh K, Jacobsen BK, Solberg S, Bønaa KH, Kumar S, Bajic R, et al. Intra- and interobserver variability in the measurements of abdominal aortic and common iliac artery diameter with computed tomography. The Tromsø study. Eur J Vasc Endovasc Surg 2003;25:399-407. Long A, Rouet L, Lindholt JS, Allaire E. Measuring the maximum diameter of native abdominal aortic aneurysms: review and critical analysis. Eur J Vasc Endovasc Surg 2012;43:515-24. Tarlov IM. Acute spinal compression paralysis. J Neurosurg 1972;36:10-20. Ferrer C, Cao P, De Rango P, Tshomba Y, Verzini F, Melissano G, et al. A propensity-matched comparison for endovascular and open repair of thoracoabdominal aortic aneurysms. J Vasc Surg 2016;63:1201-7.
16. Hu Z, Li Y, Peng R, Liu J, Jia X, Liu X, et al. Multibranched stent-grafts for the treatment of thoracoabdominal aortic aneurysms: a systematic review and meta-analysis. J Endovasc Ther 2016;23:626-33. 17. Spanos K, Kölbel T, Theodorakopoulou M, Heidemann F, Rohlffs F, Debus ES, et al. Early outcomes of the t-Branch off-the-shelf multibranched stent-graft in urgent thoracoabdominal aortic aneurysm repair. J Endovasc Ther 2018;25:31-9. 18. Dijkstra ML, Vainas T, Zeebregts CJ, Hooft L, van der Laan MJ. Editor’s choicedspinal cord ischaemia in endovascular thoracic and thoraco-abdominal aortic repair: review of preventive strategies. Eur J Vasc Endovasc Surg 2018;55:829-41. 19. Maier S, Shcherbakova M, Beyersdorf F, Benk C, Kari FA, Siepe M, et al. Benefits and risks of prophylactic cerebrospinal fluid catheter and evoked potential monitoring in symptomatic spinal cord ischemia low-risk thoracic endovascular aortic repair. Thorac Cardiovasc Surg 2018 May 1. [Epub ahead of print]. 20. Epstein NE. Cerebrospinal fluid drains reduce risk of spinal cord injury for thoracic/thoracoabdominal aneurysm surgery: a review. Surg Neurol Int 2018;9:48. 21. Luehr M, Salameh A, Haunschild J, Hoyer A, Girrbach FF, von Aspern K, et al. Minimally invasive segmental artery coil embolization for preconditioning of the spinal cord collateral network before one-stage descending and thoracoabdominal aneurysm repair. Innovations (Phila) 2014;9:60-5. 22. Mangialardi N, Lachat M, Esposito A, Puippe G, Orrico M, Alberti V, et al. The “open branch” technique: a new way to prevent paraplegia after total endovascular repair of thoracoabdominal aneurysm. Catheter Cardiovasc Interv 2016;87:773-80.
Submitted Jun 26, 2018; accepted Sep 1, 2018.
The “bare branch” for safe spinal cord ischemia prevention after total endovascular repair of thoracoabdominal aneurysms Matteo Orrico, MD,a Sonia Ronchey, MD, PhD,a Carlo Setacci, MD,b Alessio Vona, MD,a Mario Marino, MD,a Fabrizio Nesi, MD,a Alessia Giaquinta, MD,a and Nicola Mangialardi, MD,a Rome and Siena, Italy
ABSTRACT Objective: Staged endovascular treatment of thoracoabdominal aortic aneurysms (TAAAs) with temporary perfusion of the sac through a branch left unstented or a dedicated branch is a strategy intended to reduce the risk of postoperative spinal cord ischemia (SCI). However, potential complications of this approach are aneurysm sac progression between stages, visceral embolism, and occlusion or displacement of components. We here present the “bare branch” technique, a safe adjunct to TAAA repair in terms of interstage complications. Methods: In the first step, one branch, preferentially the one for the celiac trunk, is stented by a bare stent; in the second step, the bare branch is relined with a covered stent. There were 32 TAAAs (5 type I, 6 type II, 16 type III, 5 type IV) treated by this approach at our center from January 2015 to December 2017 (median follow-up, 13 months [range, 2-24 months]). Data were prospectively collected and retrospectively analyzed. Primary end points were aneurysm sac exclusion and freedom from major adverse events, which included SCI. Secondary end points were freedom from aneurysm growth between the stages and freedom from minor adverse events. Results: Preoperative mean maximum diameter was 68.4 mm; 32 endografts (8 off-the-shelf and 24 custom-made devices) were used. The mean aortic coverage was 364 mm. The mean interval time between the two stages was 10.5 weeks (range, 7-20 weeks). In-hospital mortality was 0%. Type I or type III endoleak rate was 3.2%, whereas one type II endoleak was registered (3.2%). Two patients showed paraparesis, one after the first stage and one after the second stage, both noted at 4/5 on the Tarlov scale, and fully recovered so that the SCI rate was 6.4% with 0% permanent neurologic deficit. Interstage mean maximum diameter was 68.6 mm (P > .05). After the second step, there was an average of 4.7 spinal arteries (standard deviation, 1.4; P < .05) per patient with an increase in visibility and of diameter by 0.7 mm (standard deviation, 0.4 mm). Conclusions: This is a reproducible adjunct to staged TAAA endovascular repair. The use of a bare branch instead of a branch left completely open has the clear advantage of an easy catheterization in the second step. Furthermore, by having the target vessel stented with a bare stent, the risk of embolism is avoided. In this experience, there was no significant aneurysm sac growth in between the steps. Further comparative studies may determine whether there are different hemodynamic forces with this technique with respect to those already described in the literature. (J Vasc Surg 2018;-:1-9.) Keywords: Thoracoabdominal aortic aneurysm; BEVAR; FEVAR; Paraplegia; Spinal cord ischemia
Open repair is still considered the “gold standard” of thoracoabdominal aortic aneurysm (TAAA) treatment, with good results in high-volume centers, especially in
From the Department of Vascular Surgery, San Camillo Forlanini Hospital, Romea; and the Department of Vascular Surgery, University Hospital of Siena, Siena.b Author conflict of interest: none. Presented in the International Forum at the 2018 Vascular Annual Meeting of the Society for Vascular Surgery, Boston, Mass, June 20-23, 2018. Correspondence: Matteo Orrico, MD, Vascular Surgery Department, San Camillo Forlanini Hospital, Circonvallazione Gianicolense 87, 00152 Rome, Italy (e-mail: [email protected]). The editors and reviewers of this article have no relevant financial relationships to disclose per the JVS policy that requires reviewers to decline review of any manuscript for which they may have a conflict of interest. 0741-5214 Copyright Ó 2018 by the Society for Vascular Surgery. Published by Elsevier Inc. https://doi.org/10.1016/j.jvs.2018.09.027
young patients.1 Nevertheless, fenestrated and branched endovascular aneurysm repair by custom-made or off-the-shelf devices (t-Branch; Cook Medical, Bloomington, Ind) has promising results in terms of mortality and morbidity, now confirmed by long-term follow-up.2,3 However, spinal cord ischemia (SCI) due to an extensive aortic coverage, with a frequency ranging from 0% to 31%,4,5 is a potentially disastrous complication that dramatically affects both the physical and psychological aspects of the postoperative life of the patient. Several approaches have been proposed to minimize the risk of paraplegia, such as motor evoked potential monitoring, controlled mean arterial pressure, cerebrospinal fluid drainage (CFD), and staged repair.6,7 Staged repair in particular has the aim of enhancing the collateral network supplying the spinal cord by a gradual exclusion of the aneurysm and by the following gradual and relative spinal cord hypoxia, which 1
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stimulates neoangiogenesis.7,8 The technical adjunct of an aneurysm sac “perfusion branch” was initially described in a case report and subsequently in case series. In a first step, the aortic component is deployed and the aneurysm sac is kept perfused by one or more visceral branches left open or, rarely, by a branch dedicated to temporary aneurysm sac perfusion (TASP). Eventually, in the second step, the visceral arteries are stented by the bridging stents, and the repair is completed.6,7,9 Despite the good results in terms of decreased SCI, some concerns about this approach arise from the substantial aneurysm growth rate after long interstage time, probably because of a high-flow input to the sac through the branch left completely open without an outflow. Another issue that has been highlighted with such an approach is the theoretical risk of open branch occlusion in particular conditions (ie, compression).7 Furthermore, the ongoing thrombosis of the aneurysmal aorta is theoretically accompanied by a certain risk of embolic complications, which can involve the unstented visceral vessels. The objective of the study was to investigate the results of the “bare branch” repair as a valid staged alternative to the classic perfusion branch.
METHODS This study conforms to the Declaration of Helsinki. Informed consent was collected from every patient. Eligibility and selection of patients From January 2015, the bare branch technique was used at our center for every TAAA that we intended to treat by an aortic endograft having at least one branch. Exclusion criteria were emergency/urgency setting because of the risk of keeping an unstable sac (either ruptured or symptomatic) temporarily perfused and thoracic aortic aneurysm treated with endografts having only fenestrations. Until December 2017, there were 32 patients with a TAAA (5 type I, 6 type II, 16 type III, and 5 type IV Crawford extent aneurysms) treated by this approach. Data were prospectively collected in an institutional database and retrospectively reviewed. Primary end points were aneurysm sac exclusion and freedom from major adverse events, which included SCI. Secondary end points were freedom from aneurysm growth between the stages and freedom from minor adverse events. Imaging preoperative study and follow-up Contrast-enhanced computed tomography angiography (CTA; slice thickness #0.5 mm) was always performed preoperatively. The mean period between preoperative CTA acquisition and the first stage was 3.5 months (mean, 2.8 months; range, 1.5-3.5 months). A second CTA scan was always scheduled and acquired 1 to 2 weeks before the second stage and
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ARTICLE HIGHLIGHTS d
d
d
Type of Research: Retrospective single-center cohort study of prospectively collected data Take Home Message: Staged branched endovascular repair of 32 thoracoabdominal aortic aneurysms using a bare stent for temporary aneurysm sac perfusion prevented permanent spinal cord ischemia in all patients, with no mortality. Recommendation: The use of a bare branch in patients who undergo branched endovascular aneurysm repair appears to decrease paraplegia and mortality. It has the advantage of easy catheterization in the second step and no risk of embolization.
never <6 weeks after the preceding step. All patients underwent a postoperative CTA control scan 30 days after the second step and yearly thereafter. A contrastenhanced ultrasound examination was performed 6 months after the second step and then yearly (Fig 1). All the CTA examinations were independently reviewed and analyzed by two investigators (M.O. and S.R.) using the same postprocessing software (Aquarius; TeraRecon, San Mateo, Calif). A priori “acceptable” differences for the interobserver variability were set for each measurement as follows: 3.0 mm for aortic diameter measurements; 0.5 mm for diameter of lumbar and intercostal arteries; and 15% for number of lumbar and intercostal arteries. These values were chosen on the basis of clinical expert opinion of the vascular surgeons involved in the study supported by literature reports of aortic CTA measurements.10-13 For these parameters, an interobserver Lin concordance correlation coefficient (LCCC) was used to determine interobserver agreement based on these differences with the a value being set to .05 (95% confidence interval). An LCCC <0.90 signified poor agreement, 0.90 to 0.95 was moderate, 0.95 to 0.99 was substantial, and >0.99 indicated almost perfect agreement. All statistical analyses were performed using SPSS statistical software (version 22.0; IBM Corp, Armonk, NY). SCI preventive measures Further preventive measures were always taken in both stages. Mean arterial pressure was always kept $80 mm Hg intraoperatively and for the subsequent 72 hours after both the first and second stages. Routine prophylactic CFD was used for every patient in both steps, except for the five type IV TAAAs, in which CFD was used only for the second step. CFD was always retained for 48 hours postoperatively in the absence of complications with a target cerebrospinal fluid pressure of 10 mm Hg. Neurologic evaluation was invariably performed by the same neurologist and expressed on the Tarlov scale whenever an impairment was evident or suspected and then repeated every day for the first 3 days and every 3 days until discharge.14
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Fig 1. Computed tomography angiography (CTA) volume rendering through the stages. A, Preoperative CTA of a type II thoracoabdominal aortic aneurysm (TAAA). B, CTA before the second step. The aneurysm sac is perfused through the bare branch positioned in the celiac trunk; two new segmental arteries are visible (arrow). C, CTA at 30 days after the bare branch relining.
Technique First step. In the first step, under general anesthesia, the main graft is deployed. From a femoral access, all fenestrations and respective target vessels are catheterized and connected by bridging covered stents. From a brachial access, all branches but one, preferentially the celiac trunk branch, are also catheterized and connected to the respective visceral vessels by bridging covered stents. Finally, the last branch is catheterized and connected to the last target vessel with a bare stent. Angiography confirms the presence of the intentional endoleak (Fig 2). Second step. The second step is performed a minimum of 6 weeks after the first step. Under local anesthesia and systemic heparinization, through a percutaneous brachial access (maximum 8F), the bare branch is catheterized. A noncompliant balloon is inflated for the whole length of the bare branch to simulate exclusion of the aneurysm sac, which is assessed by angiography; the balloon is then kept to nominal pressure for 20 minutes while the patient is monitored. In cases in which the patient would show any neurologic lower limb impairment, the bare stent relining is postponed. If there is no leg strength or sensibility impairment, the bare branch is relined with a covered stent. Final angiography confirms the aneurysm sac exclusion (Fig 3).
RESULTS There were 32 patients with a mean age of 69.9 years (standard deviation [SD], 19.9 years; range, 50-82 years) treated by the bare branch technique; demographics are summarized in Table I. The majority were type III TAAA patients. The preoperative mean aneurysm sac diameter was 68.4 mm (SD, 8.4 mm; range, 60-78 mm); 21 patients were treated with custom Cook endografts, 8 patients were treated with t-Branch (Cook), and 3 patients were treated with custom TAAA devices
Fig 2. Completion angiogram of the first step in a postdissection thoracoabdominal aortic aneurysm (TAAA) in a patient with Marfan syndrome. The sac is perfused through a bare stent in the celiac trunk. This is the only case in which a proximal covered stent (Bentley BeGraft) was deployed as a bridging stent for the bare branch and the main module. This choice was taken because initially the branch dedicated to the celiac trunk was slightly compressed by the lamella, so a stent with high radial force was chosen.
(JOTEC, Hechingen, Germany), accounting for a total of 123 target vessels with an average number of 3.84 visceral vessels per patient. First-step features. The mean duration of the first step was 3.2 hours (SD, 0.7 hours; range, 2.5-5.0 hours), and it was always performed under general anesthesia. The perioperative patency rate was 99.2%. In one case, we were not able to catheterize the celiac trunk from an upper access, so the dedicated inner branch was closed with a plug; and in the same session and from a femoral
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Fig 3. Second-step angiograms in a renal bare branch patient. A, The initial angiogram confirms perfusion of the aneurysm sac through the bare stent struts. B, An angiogram obtained once a balloon is inflated to confirm the effective reversible 20-minute sac exclusion and for neurologic testing. C, Second-step completion angiogram. The bare branch is relined with a covered stent, and the sac is finally excluded.
Table I. Demographics of bare branch population Demographics
% (No.)
Male
75 (24)
Hypertension
87 (28)
Smoke
66 (21)
Ischemic cardiomyopathy
53 (17)
Dyslipidemia
78 (25)
Chronic obstructive pulmonary disease
44 (14)
Diabetes
25 (8)
Renal failure Mild Severe, dialysis Connective tissue disease, Marfan syndrome ASA class 3-4 Prior vascular interventions
Monolateral chronic hypogastric occlusion
22 (7) 3 (1) 3 (1) 75 (24) 9 (3; 1 Bentall procedure, 1 frozen elephant trunk, 1 EVAR) 6 (2)
Crawford aneurysm extent I
16 (5)
II
18 (6)
III IV
50 (16, 1 postdissection aneurysm) 16 (5)
ASA, American Society of Anesthesiologists; EVAR, endovascular aneurysm repair.
access, the celiac trunk was coil embolized. In this patient as well as in another one treated by a Cook custom graft with only two branches (one for a common celiac-mesenteric trunk and one for a right renal artery; the left renal artery was aneurysmatic and chronically thrombosed), the bare branch target vessel was a renal
artery, so that the target bare branch was the celiac trunk in 93.7% of cases and a renal artery in 6.3% of cases. In these patients, serum creatinine levels were normal enough to allow a safe 20-minute warm ischemia under systemic heparinization, and they showed no postoperative serum creatinine level increase. The mean aortic coverage was 364 mm (SD, 110 mm; range, 250-490 mm), and the mean supraceliac coverage was 230 mm (SD, 95 mm; range, 135-270 mm). For the bare branch, the Protégé (Medtronic, Santa Rosa, Calif) was used in all the patients; the overall number of stents used in the first procedure was 159 (22 Fluency Plus [Bard Peripheral Vascular, Tempe, Ariz]; 74 BeGraft Peripheral [Bentley Innomed, Hechingen, Germany]; and 62 Advanta V12 [Atrium Europe B.V., Mijdrecht, The Netherlands]). The median hospital stay after the first intervention was 12.9 days (range, 7-23 days). No major in-hospital complications occurred after the first procedure with the exception of a paraparesis, noted at 4/5 according to the Tarlov scale; this occurred in a 78-year-old woman with a history of endovascular aneurysm repair (with a suprarenal fixation endograft) 5 years before. Her history was also positive for a Bentall procedure for an ascending aortic aneurysm 1 year before as well as for ischemic cardiomyopathy and hypertension. She came to our attention with a type III TAAA and patent hypogastric arteries; a repair was planned with a custom Cook graft with one fenestration for her sole renal artery and two branches for the superior mesenteric artery and celiac trunk. The procedure was uneventful, but right after the patient was readmitted to the service from the intensive care unit on the first postoperative day, with spinal drainage still installed, she experienced lack of leg strength bilaterally and needed crutches to walk; sphincters were unharmed. A highdose methylprednisone protocol, with a bolus of 30 mg/kg and 5.4 mg/kg/h for the subsequent 48 hours, was administered; the drainage was kept in place for
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Table II. Relevant computed tomography angiography (CTA) findings preoperatively, between the two steps, and 1 month after the second step Preoperative CTA
Interstage CTA (mean interval after CTA 1 month after the first step, 20.2 weeks) the second step
P value, ANOVA test for repeated measures
Aneurysm maximum diameter, mm
68.4
68.6
68.6
.363
Segmental arteries along the aorta
19.3
14.4
12.5
.002
Average diameter of segmental artery visible in the first and second CTA scans (thrombosed after the second CTA scan), mm
2.1
2.3
e
.004
Average diameter of segmental arteries visible in all three CTA scans, mm
1.7
1.9
1.9
.004
ANOVA, Analysis of variance. Of note, the aneurysm diameter did not show a significant increase despite the long waiting time between the two steps. The counted spinal arteries along the aorta showed a significant increase in diameter.
48 hours, with a target pressure of 10 mm Hg (a slight hypertension of 17 mm Hg was noted initially but was transient and easily manageable with drainage). On the third postoperative day, her symptoms regressed completely. The minor complication rate was 6.4%. We registered one brachial hematoma, which required a revision, and one mild alteration of renal function (serum creatinine level increase by 40%). Second-step features. The second step was performed at an average time of 10.5 weeks (SD, 3.5 weeks; range, 7-20 weeks) after the first step. In the time between the two stages, no vessel or bare branch occlusions were registered, and there were no unplanned hospital admissions. This step was always performed under local anesthesia and in 97% of the cases from a brachial access. The access was femoral in only one case (3.1%) for the patient described before, treated with a JOTEC custom-made device, in which the bare branch to be relined was in an upward inner branch for the left renal artery. The mean access size was 7.25F (SD, 1.25F; range, 6F-9F). As the noncompliant balloon for simulation of aneurysm sac exclusion and neurologic clinical intraoperative testing, we always used a Mustang balloon (Boston Scientific, Marlborough, Mass), and it was always of the same nominal diameter as the bare branch. Suspension of the procedure was never necessary as no neurologic lower limb impairments were noted at the 20-minute evaluation. In 87.1% of cases, the covered stent used was the Fluency Plus; in the remaining 12.9% of cases, it was a BeGraft. Closure was always obtained by manual compression. The mean duration of the second step was 39.1 minutes (SD, 8 minutes; range, 31-72 minutes). No major complications were registered after this step, and like after the first step, one paraparesis at 4/5 on the Tarlov scale was registered, in this case on the second postoperative day. This occurred in a 75-year-old male
diabetic with ischemic cardiomyopathy who presented with a type II TAAA and patent hypogastric arteries. He was treated in a first stage with a t-Branch overlapped with two proximal thoracic modules. Following removal of the CFD after bare branch relining, he experienced a mild walking impairment with reduced leg strength bilaterally. The CFD was replaced and kept for 48 hours with a target pressure of 10 mm Hg, and the high-dose methylprednisone protocol was started (see before, first-step features). The symptoms fully regressed after 3 days. No complications relative to the second puncture of the CFD were registered. Patients were discharged after an average hospitalization time of 3.3 days (SD, 1.3 days; range, 2-5 days) following the procedure. Postoperative follow-up. The median postoperative follow-up was 13 months (range, 2-24 months). No aneurysm-related mortality was registered during this period; two deaths were registered at 15 and 20 months, one for a lung adenocarcinoma and one for an acute myocardial infarction. No neurologic events were noted after the discharge. No target vessel or branch occlusions were registered at median follow-up. One (3.2%) type II endoleak was evident after the 30-day CTA examination and is currently under surveillance; it has not shown evidence of growth so far. Another endoleak (3.2%) appeared on the 1-year CTA control scan and was due to a first-generation BeGraft fracture on the celiac trunk branch. It was promptly relined with a BeGraft Plus, so that the reintervention rate was 3.2%. CTA analysis. CTA relevant findings are summarized in Table II. The mean maximum aortic preoperative diameter was 68.4 mm (SD, 8.6 mm; LCCC, 0.97); the mean diameter at interstage CTA was 68.6 mm (SD, 7.6, mm; LCCC, 0.97). They were not significantly different at the analysis of variance (ANOVA) test for repeated measures (P ¼ .363; Fig 4). The second CTA study was
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DISCUSSION
Fig 4. Box plot graphically showing the results of the analysis of variance (ANOVA) test for preoperative and postoperative aneurysm sac maximum diameter. Despite a long interstage time, no significant aneurysm growth was evident. CTA, Computed tomography angiography.
performed at an average time of 20.2 weeks (SD, 11 weeks; range, 9-28 weeks) from the first one and at 1.2 weeks (SD, 0.8 weeks; range, 1-2 weeks) before the bare branch closure. The 1-month postoperative diameter (68.6 mm; SD, 31 mm; LCCC, 0.97) was not significantly different (P > .05). Twenty-one (66%) patients completed the 1-year follow-up, and in this subgroup there was a significant shrinkage of the aneurysm sac (70.2 mm vs 63.6 mm; P < .05). The segmental arteries along the aorta were 19.3 preoperatively and 14.4 between stages; 12.5 remained visible after the second step (P < .05; LCCC, 0.97, 0.97, 0.96, respectively). On analyzing the uncovered segmental artery group between the first and second steps, an average of 4.7 of them (SD, 1.3; range, 3-5; P < .05; LCCC, 0.96) showed an increase in visibility and by 0.7 mm in diameter (SD, 0.4 mm; Figs 5 and 6). The mean diameter of the subgroup of spinal arteries that were visible until the second step was 2.1 mm (SD, 0.4 mm; range, 1.0-2.5 mm) on preoperative CTA and 2.3 mm (SD, 0.4 mm; range, 1.0-2.7 mm) on the interstage CTA (ANOVA test for repeated measures, P < .02). The mean diameter of the subgroup of spinal arteries that remained visible after the second stage also increased significantly on comparing the preoperative diameter with the final result. At any rate, there was no significant difference between their average diameter on interstage CTA vs 1-month CTA (1.7 mm [SD, 0.5 mm]; 1.9 mm [SD, 0.4 mm]; 1.9 mm [SD, 0.4 mm]; Fig 7; ANOVA test for repeated measures, P < .05 for the three CTAs; ANOVA test for repeated measures, P ¼ .168 for the interstage vs 1-month CTA).
SCI, which can lead to paraplegia, is a potentially devastating complication that still negatively affects the outcomes of both open and endovascular treatment of TAAAs. With regard to fenestrated and branched endovascular repair of TAAA, several SCI preventive measures have been described; but despite those, the incidence of such complication is still high, ranging from 5% to 30% in the latest reports.5,15-17 In a review of preventive strategies used for thoracic and thoracoabdominal repair, Dijkstra et al18 recently reported improved results for both transient and permanent SCI in the last years. However, they also highlighted a lack of evidence on this topic that makes it impossible to create definitive recommendations as to which type of preventive measures to adopt. Perioperative hypotension avoidance or controlled hypertension and permissive temporary endoleak have been reported as valid strategies to lower SCI. For other measures, such as prophylactic CFD and neuromonitoring, the findings are more conflicting. Furthermore, there is no clear association between preventive strategies, alone or in association, and the persistence of SCI, which is however more frequently temporary.18-20 Staged procedures and permissive endoleak have their rationale in the spinal cord preconditioning mechanism. It has been demonstrated that a relative and sustained spinal cord hypoperfusion causes several morphologic changes in its blood supply (enlargement, redistribution, reorientation of the segmental arteries), which are the target of the “minimally invasive segmental artery coil embolization” technique as well as of TASP.7-9,21 TASP, in particular, described by Kasprzak et al in 2014, is accompanied by an SCI rate of 5% and consists of the temporary perfusion of the sac by a branch left completely open, dedicated to either a renovisceral vessel or the TASP itself.7-9 In the TASP experience, even with good results in terms of SCI, some drawbacks are evident. Primarily, aneurysm sac progression is relevant, being as high as 26% for interstage periods >4 weeks and 12.5% on the 48-day mean interstage time of the overall experience. This is probably due to a high-flow input to the aneurysm sac through the branch left completely open, without an outflow. The mortality rate between the two steps is also not negligible; the aneurysm-related mortality is 12.5% (one case of aneurysm rupture). Another concern with this technique is the potential risk of component disconnection and misalignment and even occlusion that may arise from the lack of support with not having all the target vessels stented; for the technique, one failure of recatheterization is reported. Finally, the progressive aneurysm sac thrombosis, which is intended to enhance the spinal cord supply, may, on the other hand, involve unstented vessel ostia with a consequent risk of occlusion. The
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Fig 5. Favorable changes of a segmental artery are evident at computed tomography angiography (CTA) through the stages. A, Preoperative CTA. B, On CTA before the second step, the segmental artery shows a 0.5-mm increase in diameter. C, On final CTA, the diameter of the segmental artery has a slight new increase.
Fig 6. Favorable changes of median sacral artery (indicated by the red arrow) on computed tomography angiography (CTA) through the stages. A, Preoperative CTA. B, On CTA before the second step, the median sacral artery is more evident. C, On final CTA, the median sacral artery gains further visibility.
authors sustain the hypothesis that the TASP approach may have better results once there will be a way to control the blood flow through the branch. We already described our “open branch” method in a three-case experience in 2015. We reported a successful two-step exclusion of three TAAAs, with two of them leaving the sac perfused by a bridging bare stent in the celiac trunk and with one through a bare stent placed instead of an iliac limb.22 In this current experience, which does not include those three cases previously reported, we describe our results of a larger cohort treated homogeneously as we standardized our approach after those three cases. With the bare branch, we aim to offer a safe alternative to the already described TASP. There are three main reasons that we preferentially use the celiac trunk as a target for the bare branch. First, it is the most proximal of the vessels to stent in TAAA repair
and so the closest to the “critical” zone in speaking about spinal cord vascularization. Furthermore, access to the celiac trunk is usually more straightforward than to other branches, and it is less frequently involved in abdominal tortuosity and therefore easier to catheterize in the second step. Finally, the parenchyma vascularized by the celiac trunk is more resistant to the endoclamping that will be done in the second step in comparison to the kidneys, for example. After our observations in the experience with the first three patients,22 in which no sac growth was evident, we considered 6 weeks the minimum interval at which to schedule the second procedure. We wanted a safe waiting time, long enough to develop a collateral spinal cord vascularization. The long time between the steps is principally due to the availability of patients to be hospitalized for a second step; this is a pitfall to consider as patients generally think of this second intervention as
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step; on the contrary, we found the second step very easy, primarily because of the previously implanted bare stent. The long interval time in the absence of significant major adverse events with an SCI rate in line with reported rates shows that this method is a safe and reproducible adjunct to the staged repair of TAAAs.
CONCLUSIONS
Fig 7. Box plot graphically showing the results of the analysis of variance (ANOVA) test for the mean diameter of the segmental arteries that are evident on preoperative, interstage, and 30-day computed tomography angiography (CTA). An increase in diameter is evident through the stages.
a minor procedure and need to be urged more than once before they call themselves ready to undergo this second step. CTA performed just before the second step always showed a partial sac thrombosis. Our SCI rate is 6.4% and 9% if only type I and type II TAAAs are considered, which is comparable with the current literature reports, with 0% of permanent deficit. As for reinterventions, we report one case of stent fracture. Initially, we hypothesized that this may have resulted from an unfavorable materials interaction between the BeGraft deployed in the second step and the surrounding bare stent deployed in the first step. However, we subsequently noticed that the fractured stent was part of a BeGraft generation for which a high rate of fractures was noted, mostly when they were used for branch configurations. Noteworthy, however, is the fact that despite a time between the two procedures that was longer than the average time reported in the literature, we did not register any relevant aneurysm sac progression. However, in line with the previous literature findings, we did notice some relevant morphologic CTA changes in the spinal cord vascularization, such as the increase in diameter of the uncovered segmental arteries.6,7 An advantage of the bare branch derives from the fact that using a bare stent instead of a branch left completely open may give one more fixation zone to the complex with a consequent increase in stability, and having all the target vessels and branches stented protects the patients from occlusion. In fact, we did not observe cases of branch or target vessel occlusion and never failed to catheterize the branch in the second
The bare branch appears to be a reproducible and safe adjunct to staged TAAA endovascular repair. It is effective in terms of SCI prevention and has the advantage of an easy completion in the second step and an enhanced protection to the target vessels and ostia between the steps. Unlike what is reported in the literature for other SCI preventive methods, our experience was not accompanied by relevant aneurysm sac growth. Further studies with control groups may highlight whether different hemodynamic forces play a role in this finding. The authors acknowledge Michael Tarullo, Adjunct Professor, School of Science, Monmouth University, Long Branch, NJ, for language revision.
AUTHOR CONTRIBUTIONS Conception and design: MO, SR, CS, NM Analysis and interpretation: MO Data collection: MO, SR, AV, MM, FN, AG Writing the article: MO, NM Critical revision of the article: MO, SR, CS, AV, MM, FN, AG, NM Final approval of the article: MO, SR, CS, AV, MM, FN, AG, NM Statistical analysis: MO Obtained funding: Not applicable Overall responsibility: NM
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Submitted Jun 26, 2018; accepted Sep 1, 2018.