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Promoting False-Lumen Thrombosis after Thoracic Endovascular Aneurysm Repair in Type B Aortic Dissection by Selectively Excluding False-Lumen Distal Entry Tears
CLINICAL STUDY
Promoting False-Lumen Thrombosis after Thoracic Endovascular Aneurysm Repair in Type B Aortic Dissection by Selectively Excluding False-Lumen Distal Entry Tears Mikolaj Wojtaszek, MD, PhD, Emilia Wnuk, MD, Rafal Maciag, MD, Krzysztof Lamparski, MD, Krzysztof Korzeniowski, MD, and Olgierd Rowinski, MD
ABSTRACT Purpose: To evaluate the efficacy and clinical outcomes of ancillary endovascular procedures in promoting false-lumen (FL) thrombosis (FLT) and preventing aortic expansion in patients after thoracic endografting for type B dissections. Materials and Methods: This retrospective review included 15 patients (12 men and 3 women; mean age, 59.6 y). Mean aortic diameter at the time of ancillary treatment was 47.4 mm. Different techniques were used as single procedures or sequentially: covered stent occlusion of detached visceral artery entry tears, occlusion of single entry tears with vascular plugs, or aortic endograft occlusion of multiple FL entry tears. FL embolization with ethylene vinyl alcohol copolymer was performed when selective occlusion was considered insufficient to close distal entry tears. Apart from endovascular aneurysm repair, all procedures were performed percutaneously under local anesthesia. If FL diameter increase persisted after 6-month follow-up computed tomographic (CT) angiography, another intervention was planned; otherwise, yearly follow-up was performed. Results: Mean clinical follow-up duration was 43.8 months (range, 8 d to 86.8 mo), with no in-hospital mortality. Estimated overall survival rates were 93.3%, 86.6%, and 77% at 12, 24, and 48 months, respectively. Three late deaths occurred, one of which was dissection-related at 40 months. Eight surviving patients (53%) had total FLT and 3 had partial FLT with stable aortic diameter on follow-up CT angiography. FL diameter increased in one patient, requiring further intervention. Conclusions: Selective exclusion of new distal entry tears remaining after thoracic endovascular aneurysm repair can stabilize abdominal aortic expansion and promote FLT.
ABBREVIATIONS FL = false lumen, FLT = false-lumen thrombosis, TEVAR = thoracic endovascular aneurysm repair
In acute and early chronic type B aortic dissections, thoracic endovascular aneurysm repair (TEVAR) is now the dominant treatment approach and has replaced open surgical repair, which is associated with high mor-
From the Second Department of Clinical Radiology, Medical University of Warsaw, Banacha 1A, Warsaw 02-097, Poland. Received July 15, 2015; final revision received June 29, 2016; accepted July 8, 2016. Address correspondence to M.W.; E-mail: [email protected] M.W. is a paid speaker and trainer for Covidien (Dublin, Ireland). R.M. is a paid proctor and trainer for Covidien. O.R. is a paid proctor for Medtronic (Dublin, Ireland). Neither of the other authors has identified a conflict of interest. & SIR, 2016 J Vasc Interv Radiol 2016; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2016.07.007
tality rates (1). When combined with optimal medical treatment, most patients will benefit from this treatment in cases of aortic remodeling, false-lumen (FL) thrombosis (FLT), and stable aortic diameters (2,3). Although TEVAR has proven beneficial in aortic remodeling in the thoracic region adjacent to the endograft, further concern remains regarding the suprarenal and infrarenal aorta. Recent studies (4) have shown that excluding only the primary entry tear in the thoracic aorta may fail to induce thrombosis of the abdominal aortic FL because of persisting distal entry tears at this level. Partial FLT, on the contrary, is directly related to FL aneurysmal dilation and an increased risk of rupture (5,6). FLT is the ideal endpoint of therapy, as it is associated with better long-term prognosis; however, it is rarely achieved with medical treatment alone, and intervention is most
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often required to repair the dissection and promote aortic remodeling (7,8). The aim of the present study is to evaluate the efficacy and clinical outcomes of ancillary endovascular procedures in promoting FLT and preventing aortic dilation in patients after TEVAR for type B dissections.
MATERIALS AND METHODS Patient Population This retrospective single-center study was approved by the institutional review board, which waived the need for individual patient consent. Between June 2006 and December 2014, 78 patients underwent TEVAR for acute or chronic type B aortic dissection with delayed thoracic aortic dilation. Among these, during their postTEVAR follow-up, 15 patients (19%; 12 men and three women; mean age, 59.6 y) had progressive increase in FL diameter in the aorta below the implanted endograft, requiring ancillary endovascular procedures to prevent further aneurysmal expansion and attempt to achieve FLT. Five patients (33.3%) had TEVAR in an acute setting, and 10 (66.6%) had been previously treated for chronic type B dissection. Patient comorbidities are presented in Table 1.
Imaging Protocol The standard imaging protocol after TEVAR was computed tomographic (CT) angiography performed 6 months after all ancillary interventions. In cases that did not require further intervention, a 12-month follow-up interval was established. In patients in whom an increase of the aortic diameter greater than 3 mm (considered to represent FL expansion) was observed, another examination was scheduled after 6 months. CT angiography of the entire aorta, from the proximal supraaortic vessels to the common femoral arteries, was performed on a 16-row and later on a 64-row multidetector scanner (LightSpeed or Optima 660; GE Medical Systems, FairTable 1 . Patient Comorbidities and Indications for TEVAR (N ¼ 15) Comorbidity Risk Factor
Incidence
Hypertension
14 (93)
CAD Diabetes mellitus
11 (73) 6 (40)
Smoking (current or past)
11 (73)
Hypercholesterolemia Previous stroke
7 (47) 3 (20)
Cocaine abuse
1 (7)
Connective tissue disease (Marfan, Ehlers–Danlos) Renal insufficiency
0 2 (13)
Chronic obstructive pulmonary disease
3 (20)
Note–Values in parentheses are percentages. CAD ¼ coronary artery disease; TEVAR ¼ thoracic endovascular aneurysm repair.
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field, Connecticut) with a reconstruction increment of 1.25 mm. Arterial- and delayed-phase images were obtained to determine the status of the FL (ie, patent or thrombosed).
Image Analysis CT angiographic imaging was used to assess new distal entry tears between the true lumens and FLs. Changes in aortic diameter and FL status were compared at the following seven levels: left subclavian artery, carina, level of the mitral valve, celiac trunk, uppermost renal artery, and largest diameters of the infrarenal aorta and common iliac arteries. The status of the FL was classified as total thrombosis if no flow was present, as partial thrombosis if flow and thrombus were present, and as patent if only flow was present. Changes in aortic diameters between the initiation of ancillary therapies and the achievement of total FLT or stabilization of aortic diameter were calculated using base measurements obtained from axial CTA image analysis on a Syngo MMWP workstation (Siemens Medical Solutions, Erlangen, Germany).
Endovascular Procedures The intent to treat was based on observed dilation of the FL by more than 5 mm per year with persistent turbulent flow and hyperperfusion of the FL on follow-up. Excluded from the study were patients with a ruptured FL and patients with organ malperfusion as a result of dissection. Mean maximum aortic diameter at the time of initial ancillary treatment was 47.4 mm (range, 34–63 mm). Collected imaging data were used to determine remaining dominant entry tears after TEVAR. Ancillary techniques to close these tears were used in a single stage or sequentially, but always relied on initial selective occlusion of detached arterial ostia with covered peripheral stents (mainly the renal or superior mesenteric artery ostium). This technique was applied in all patients to occlude significant entry tears at the paravisceral level while retaining patency of the dissected visceral vessels. Remaining ancillary techniques included the following: (i) implantation of a vascular plug into a major proximal entry tear in the dissection flap was applied when there was direct communication between lumens, no important vessel was present, and direct occlusion could be performed; (ii) implantation of a straight or bifurcated endograft in the abdominal aorta or iliac arteries was used when proximal visceral entry tears were already eliminated to occlude the remaining distal reentry tears tears from detached lumbar arteries and to induce remodeling of the infrarenal aorta; and (iii) embolization of an FL proximal or distal endoleak with ethylene vinyl alcohol copolymer (Onyx 34; Covidien, Dublin, Ireland) was performed as a last resort in cases in which an entry tear remained but could not be treated with the other described methods. To avoid nontarget embolization,
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detachable coils (Concerto; Covidien) were used as a scaffold for the liquid embolic agent. All ancillary procedures were performed percutaneously through the common femoral arteries or left axillary artery under local anesthesia in the interventional radiology suite. Stent grafts and iliac limb extensions were implanted with a surgical cutdown through the common femoral arteries under epidural anesthesia in the surgical operating theater. When occluding entry tears in the renal or superior mesenteric artery, cannulation of the detached ostium in the FL and then the true lumen of the artery was performed. Next, a peripheral stent graft (Advanta V12 [Atrium, Hudson, New Hampshire] or VIABAHN [W.L. Gore & Associates, Flagstaff, Arizona]) was deployed across both orifices, creating a connection between the artery and the true lumen while excluding a major distal entry tear at this level (Fig 1). In the later cases, the balloon-expandable peripheral stent graft (Advanta V12; Atrium) was reinforced with a selfexpanding nitinol stent (EverFlexþ; Covidien) to prevent kinking. In two cases, the FL in the thoracic aorta was cannulated through an intimal defect in the true lumen arising from a detached ostia of an intercostal artery, and a self-expanding stent (EverFlexþ; Covidien) was expanded in the dissection flap orifice, between the two lumens. Inside this stent, an AMPLATZER Vascular Plug type 2 (St. Jude Medical, St. Paul, Minnesota) was deployed to exclude the distal entry tear (Fig 2). The stent was used for positioning and as a scaffold to accommodate a large 10-mm AMPLATZER Vascular Plug type 2 because a smaller plug would not occlude the tear. The technique of occlusion of distal reentry tears in the abdominal aorta with a bifurcated endograft, endograft limb, and covered balloon-expandable stent or selfexpanding aortic stent did not differ significantly from standard everyday techniques of endovascular aortic
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repair. In patients in whom the previously mentioned techniques did not stabilize FL expansion, the perfused portion of the FL was embolized with ethylene vinyl alcohol copolymer (Onyx 34; Covidien). This technique was performed only when it was assumed that a single untreated entry tear remained that was causing local hyperperfusion and progressive growth of the FL. After angiographically ensuring that the blood supply to the spinal cord would not be affected, a dimethyl sulfoxide– compatible microcatheter (Rebar-18; Covidien) was introduced into the FL, and ethylene vinyl alcohol copolymer (Onyx 34; Covidien) was applied over a detachable coil scaffold (Concerto; Covidien) in a continuous manner until occlusion of the entire FL was perceived under angiographic control (Fig 3). Ethylene vinyl alcohol copolymer (Onyx 34; Covidien) was chosen in these lastresort situations as a controllable liquid embolic agent with a documented history of efficacy in the treatment of endoleaks after endovascular aortic repair. Postprocedural antiplatelet therapy in all patients consisted of 75 mg of acetylsalicylic acid. Patients were followed up with CT angiography 6 months after each ancillary intervention. If the FL diameter increase was persistent, further ancillary interventions were planned. Statistical analysis was performed by using SPSS software (version 20.0; SPSS, Chicago, Illinois). Estimated survival curves were calculated on the basis of the Kaplan–Meier estimate and are presented as life tables.
RESULTS The mean follow-up time between the first ancillary intervention after TEVAR and the last imaging study was 43.8 months (range, 8 d to 86.8 mo), with a 0% inhospital mortality rate. Estimated overall survival rates were 93.3%, 86.6%, and 77% at 12, 24, and 48 months,
Figure 1. Implantation of a covered peripheral stent at the level of the detached renal artery ostium. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrowhead) in the detached renal artery. (b) A covered stent (VIABAHN; W.L. Gore & Associates; arrowhead) was implanted connecting the true aortic lumen with the renal artery, and (c) control angiography shows perfusion of the right kidney from the true lumen via the implanted covered stent (arrowhead), with no leakage to the FL.
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Figure 2. Implantation of a vascular plug into a major proximal entry tear in the dissection flap. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrowhead) in the dissection flap at the level of the thoracic aorta. (b) A self-expanding stent (EverFlexþ; Covidien; arrowhead) was implanted through the distal entry tear, and (c) an AMPLATZER Vascular Plug type 2 (St. Jude Medical; arrow) was implanted into the stent (arrowhead) to eliminate flow into the FL. (d) Control angiography showing full perfusion of the true lumen with no leakage into the FL.
respectively (Fig 4). Three deaths occurred (20%), of which one was dissection-related at 40 months. One patient was lost to follow-up. All patients presented with a single FL. Mean number of entry tears per patient was 2.6 (range, 1–4). Among 15 consecutive patients undergoing ancillary procedures after TEVAR, 11 (73%) had more than one procedure performed before a stable aortic diameter could be achieved on follow-up. Patient data showing treated entry tears and FL patency/ thrombosis are presented in Table 2. The intended technical success was achieved in all cases except one in which it was impossible to introduce a covered stent into the celiac trunk. Completion angiography revealed patent main branch vessels with
minimal persistent flow into the FL at the level of attempted sealing. The first death, considered to be dissection-related, occurred 40 months after the last ancillary procedure. A review of CT angiographic images revealed misinterpreted hyperperfusion of the FL from the remaining proximal entry tear with minimal but present increases in FL between consecutive studies leading to rupture. The last recorded follow-up data for the second patient who died is from 8 months after implantation of a covered stent into the superior mesenteric artery. On follow-up CT angiography, a slight increase (13%) in the partially thrombosed FL at the level of the celiac axis was observed, whereas the remainder of the FL was thrombosed. A telephone
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Figure 3. Embolization of an FL proximal or distal endoleak with ethylene vinyl alcohol copolymer. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrow) in the dissection flap at the level of the visceral arteries. (b) Control angiography shows a single pair of lumbar arteries draining the perfused pouch (arrowheads) in the FL. (c) Control angiogram shows ethylene alcohol copolymer (Onyx 34; Covidien) over a detachable coil scaffolding (Concerto; Covidien) filling the pouch completely (arrowheads) without nontarget embolization.
level of the celiac trunk using the femoral access, and another attempt will still have to be made from another access route.
DISCUSSION
Figure 4. Life table plotting cumulative survival against time (in months) between the first intervention and the last imaging study in patients who have undergone ancillary intervention after TEVAR.
inquiry revealed that the patient died suddenly at 14 months after treatment for this study, after a reported myocardial infarction. Finally, the third patient who died was initially lost to follow-up (3 mo after repeat intervention) and did not respond to our telephone and mail inquiries. We assume that his date of death was between 3 and 12 months and include this in survival estimate calculations. No postprocedural spinal cord ischemia was observed. Among the surviving 12 patients in the series, eight (67%) had total FLT during the follow-up period. Within this group, seven patients had total FLT in a relatively short period of time after the final procedure, between 6 days and 5 months. In a single patient, total FLT occurred 73 months after the last procedure. Three patients had partial FLT at two and three levels of the abdominal aorta with stable aortic diameters at 7, 11, and 27 months of follow-up. The remaining patient had an increase in aortic diameter at the suprarenal level of the dissected aorta on 21-month follow-up. A failed attempt was made to seal a remaining entry tear at the
Aortic remodeling after TEVAR in type B dissections is predominantly seen in the thoracic aorta, and mostly at the level of the previously implanted endograft (3). The same does not always occur in the abdominal aorta, especially in complicated dissections. Several authors have already reported this concern. Bockler et al, in their series of 50 patients undergoing TEVAR, observed total or partial FLT in 60% of patients and severe abdominal aortic expansion (4 50 mm) in five patients (10%) (9). Similar observations on the expansion of the abdominal aorta have been made by Resch et al (10) with data from a Swedish multicenter study in which 16% of patients exhibited expansion in the uncovered portion of the descending aorta, and by Gaxotte et al (11), who noted that complete FLT resulted in decreased aortic diameters, but chronic expansion of the dissected uncovered aorta continued (11,12). Although the incidence of expansion of the uncovered aorta on follow-up was reported not to exceed 20% after TEVAR, the lack of FLT, often considered as an endpoint for therapeutic success, is still an ongoing weak point of TEVAR in the treatment of type B dissections (13). Aortic segments with partial FLT have a significantly higher annual aortic growth rate, which may lead to rupture, whereas patients with total FLT and aortic remodeling have a better long-term prognosis, making it a necessity to establish proven ancillary therapies that will halt thoracoabdominal degeneration and promote complete thrombosis of the FL (14,15). Several minimally invasive techniques have already been proposed to
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Aorta
TEVAR
No. of
Extent Follow-up Duration
Pt. No Size (mm) Setting
TA
CA
SMA
RRA
LRA
RIA
LIA
1
38
Acute
TL
TL
TL
Covered stent
TL
Covered stent
Covered Stent
3
Total
2
41
Chronic
TL
TL
TL
TL
Covered stent
TL
TL
1
Patent
0.07 (Dead)
3 4
36 55
Acute Aortic SEMS Chronic TL
FL TL
TL Covered stent
TL TL
Covered stent TL
TL –
TL –
2 1
Partial Total
26.70 (Alive) 8.73 (Dead)
5 6
43 58
Chronic Chronic
TL TL
TL TL
3 3
Patent Total
40.97 (Dead) 86.83 (Alive)
7
52
Chronic
TL
TL
TL
TL
Covered stent
8 9
52 49
Acute Chronic
AVP TL
TL TL
TL TL
Covered stent Covered stent
TL TL
10
48
Chronic
AVP
TL
FL Onyx
Covered stent
TL
11 12
37 56
Acute Chronic
TL TL
TL TL
TL TL
TL TL
13
34
Acute
TL
Covered stent
14 15
63 49
Chronic Chronic
TL –
FL Onyx FL Onyx
TL
Covered stent Covered stent Covered stent TL
FL Covered stent EVAR (straight) TL
TL
TL
(mo)*/Outcome 41.33 (Alive)
Aortic SEMS
2
Total
52.96 (Alive)
Covered stent Aortic SEMS
2 2
Total Total
35.06 (Alive) 52.50 (Alive)
EVAR (bifurcated)
4
Partial
61.10 (Alive)
2 1
Partial Total
59.13 (Alive) 73.50 (Alive)
–
1
Total
27.33 (Alive)
EVAR (bifurcated) EVAR (bifurcated)
4 3
Total Patent
18.50 (Alive) 58.40 (Alive)
TL Covered stent Aortic SEMS, LIA covered stent Covered stent TL – TL
Covered stent Covered stent TL – TL Covered stent
Interventions of FLT
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Table 2 . Procedure-Related Data and Status of FL
AVP ¼ AMPLATZER Vascular Plug; CA ¼ celiac axis; EVAR ¼ endovascular abdominal aortic repair; FL ¼ false lumen; LIA ¼ left iliac artery; LRA ¼ left renal artery; RIA ¼ right iliac artery; RRA ¼ right renal artery; SMA ¼ superior mesenteric artery; TL ¼ true lumen; SEMS ¼ self-expanding metal stent (Zenith Dissection Endovascular System [Cook, Bloomington, Indiana] or Sinus-XL stent [OptiMed, Ettlingen, Germany]); TA ¼ thoracic aorta; TEVAR ¼ thoracic endovascular aneurysm repair. *Follow-up time between the first ancillary intervention after TEVAR and the last imaging study.
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address this problem, the most successful being the proposals by Oikonomou et al (16) to use fenestrated/ branched TEVAR to reestablish the true lumen and exclude the FL. Employing this technique made it possible to achieve an FLT rate of 88.2% at 12 months in a group of 31 patients. Another technique is the technique proposed by Hofferberth et al (17) consisting of coil and glue embolization of the false channel in an attempt to repair small intimal defects. In a mean follow-up of 63 months, this technique allowed for total FLT in two of 10 patients, with the remaining patients having partial FLT at the level of the abdominal aorta. Eriksson et al (18) reported the use of peripheral covered stents in the treatment of expanding FL in a subgroup of four patients presenting with complicated type B dissections and achieved a 50% total FLT rate (18). On the contrary, a different approach, the use of the “PETTICOAT (provisional extension to induce complete attachment) technique” employing a bare stent as an extension from the thoracic endograft throughout the entire abdominal aorta, failed to limit FL expansion in the abdominal segment, as reported by Melissano et al (19). The ancillary techniques presented in the present study, mainly based on occluding entry tears with covered peripheral stents, seem simpler than the previously described techniques while still stabilizing aortic expansion in 92% of surviving patients on long-term follow-up. With an in-hospital mortality rate of 0%, compared with the fairly high 9.6% mortality rate reported by Oikonomou et al (16), albeit with a lower rate of total FLT (88% vs 67%), these sequentially performed minimally invasive techniques could be useful in patients with comorbidities who would otherwise be poor candidates for fenestrated/ branched TEVAR. The application of these minimally invasive techniques involves an astute observation of the dissection flap with its entry tears, especially in cases of high flow, arising from the detached ostia of major abdominal vessels. After TEVAR and closing of the primary entry tear, the FL is predominantly perfused by a normotensive inflow through the detached abdominal arterial ostia and the outflow through the iliac/hypogastric artery, leading to pressure equilibrium and stable FL in the majority of patients (80%–90%) receiving hypotensive therapy after TEVAR (20). The remaining 10%–20% patients in whom such a pressure equilibrium cannot be naturally established as a result of impaired outflow from the FL, total FLT—or at least stability of the aortic expansion— can be achieved by excluding the remaining major entry tears. In the present study, effective depressurization of the FL was achieved in 92% of 12 surviving patients (73% overall), with total FLT in eight (67%) and partial FLT with stable aortic diameter in three (25%). On the contrary, in a retrospective analysis of the present study, in the patient who died at 40 months of follow-up, we inadvertently hyperpressurized the FL at the aortic
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bifurcation by excluding the predominant distal outflow tract through the iliac artery. This was a significant technical planning error and a reminder that these patients should be under special scrutiny during follow-up. The one remaining patient had an increase in the diameter of the FL at the level of the thoracic and suprarenal aorta at 21 months’ follow-up. All diameter increases were associated with partial FLT, a known predictor of increased annual aortic growth rate as well as an independent predictor of postdischarge mortality in these patients (21). These are problems that will have to be addressed in the near future by employing further ancillary methods such as polymer embolization (Onyx 34; Covidien) to ensure full thrombosis of the FL. In cases in which we could limit the expansion of the FL in the abdominal aorta, attempts were made to fill the remaining FL entirely with ethylene vinyl alcohol copolymer. In two cases in which relatively small quantities were needed to fill the FL, this approach was successful. In one patient in whom we attempted to fill the majority of the FL, this method proved unsuccessful, with ethylene vinyl alcohol copolymer layering at the dorsal part of the FL aorta and leaving the ventral part perfused from the still-patent reentry tears. The FL slowed down in expansion on 6-month follow-up CT angiography, but the lack of FLT may still pose a problem in the future. The observations made in the present study are limited by its retrospective nature, the small sample size, lack of randomization, inhomogeneity of dissections among the type B subtype, use of varied endovascular techniques, and patients lost without appropriate follow-up. In conclusion, properly thought out and planned selective exclusion of the remaining post-TEVAR distal entry tears at the level of the abdominal aorta appear to represent a feasible approach to promote FLT. In the majority of patients, it can effectively stabilize thoracoabdominal aortic expansion and potentially reduce mortality in these patients. Accurate follow-up of these patients is essential, as they will rarely directly benefit from a single-stage procedure. In these cases, additional measures may have to be undertaken to prevent further FL dilation, with polymer embolization considered a last-resort endovascular treatment.
REFERENCES 1. Scott AJ, Bicknell CD. Contemporary management of acute type B dissection. Eur J Vasc Endovasc Surg 2016; 51:452–459. 2. Brunkwall J, Lammer J, Verhoeven E, Taylor P. ADSORB: a study on the efficacy of endovascular grafting in uncomplicated acute dissection of the descending aorta. Eur J Vasc Endovasc Surg 2012; 44:31–36. 3. Nienaber CA, Kische S, Rousseau H, et al; INSTEAD-XL trial. Endovascular repair of type B aortic dissection: long-term results of the randomized investigation of stent grafts in aortic dissection trial. Circ Cardiovasc Interv 2013; 6:407–416. 4. Huptas S, Mehta RH, Kühl H, et al. Aortic remodeling in type B aortic dissection: effects of endovascular stent-graft repair and medical treatment on true and false lumen volumes. J Endovasc Ther 2009; 16:28–38.
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5. Sayer D, Bratby M, Brooks M, Loftus I, Morgan R, Thompson M. Aortic morphology following endovascular repair of acute and chronic type B aortic dissection: implications for management. Eur J Vasc Endovasc Surg 2008; 36:522–529. 6. Khoynezhad A, Donayre CE, Omari BO, Kopchok GE, Walot I, White RA. Midterm results of endovascular treatment of complicated acute type B aortic dissection. J Thorac Cardiovasc Surg 2009; 138:625–631. 7. Bernard Y, Zimmermann H, Chocron S, et al. False lumen patency as a predictor of late outcome in aortic dissection. Am J Cardiol 2001; 87: 1378–1382. 8. Onitsuka S, Akashi H, Tayama K, et al. Long-term outcome and prognostic predictors of medically treated acute type B aortic dissections. Ann Thorac Surg 2004; 78:1268–1273. 9. Böckler D, Hyhlik-Dürr A, Hakimi M, Weber TF, Geisbüsch P. Type B aortic dissections: treating the many to benefit the few? J Endovasc Ther 2009; 16 Suppl 1:I80–190. 10. Resch TA, Delle M, Falkenberg M, et al. Remodeling of the thoracic aorta after stent grafting of type B dissection: a Swedish multicenter study. J Cardiovasc Surg (Torino) 2006; 47:503–508. 11. Gaxotte V, Thony F, Rousseau H, et al. Midterm results of aortic diameter outcomes after thoracic stent-graft implantation for aortic dissection: a multicenter study. J Endovasc Ther 2006; 13:127–138. 12. Trimarchi S, Tolenaar JL, Jonker FH, et al. Importance of false lumen thrombosis in type B aortic dissection prognosis. J Thorac Cardiovasc Surg 2013; 145(3 Suppl):S208–S212. 13. Andacheh ID, Donayre C, Othman F, Walot I, Kopchok G, White R. Patient outcomes and thoracic aortic volume and morphologic changes following
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Promoting False-Lumen Thrombosis after Thoracic Endovascular Aneurysm Repair in Type B Aortic Dissection by Selectively Excluding False-Lumen Distal Entry Tears Mikolaj Wojtaszek, MD, PhD, Emilia Wnuk, MD, Rafal Maciag, MD, Krzysztof Lamparski, MD, Krzysztof Korzeniowski, MD, and Olgierd Rowinski, MD
ABSTRACT Purpose: To evaluate the efficacy and clinical outcomes of ancillary endovascular procedures in promoting false-lumen (FL) thrombosis (FLT) and preventing aortic expansion in patients after thoracic endografting for type B dissections. Materials and Methods: This retrospective review included 15 patients (12 men and 3 women; mean age, 59.6 y). Mean aortic diameter at the time of ancillary treatment was 47.4 mm. Different techniques were used as single procedures or sequentially: covered stent occlusion of detached visceral artery entry tears, occlusion of single entry tears with vascular plugs, or aortic endograft occlusion of multiple FL entry tears. FL embolization with ethylene vinyl alcohol copolymer was performed when selective occlusion was considered insufficient to close distal entry tears. Apart from endovascular aneurysm repair, all procedures were performed percutaneously under local anesthesia. If FL diameter increase persisted after 6-month follow-up computed tomographic (CT) angiography, another intervention was planned; otherwise, yearly follow-up was performed. Results: Mean clinical follow-up duration was 43.8 months (range, 8 d to 86.8 mo), with no in-hospital mortality. Estimated overall survival rates were 93.3%, 86.6%, and 77% at 12, 24, and 48 months, respectively. Three late deaths occurred, one of which was dissection-related at 40 months. Eight surviving patients (53%) had total FLT and 3 had partial FLT with stable aortic diameter on follow-up CT angiography. FL diameter increased in one patient, requiring further intervention. Conclusions: Selective exclusion of new distal entry tears remaining after thoracic endovascular aneurysm repair can stabilize abdominal aortic expansion and promote FLT.
ABBREVIATIONS FL = false lumen, FLT = false-lumen thrombosis, TEVAR = thoracic endovascular aneurysm repair
In acute and early chronic type B aortic dissections, thoracic endovascular aneurysm repair (TEVAR) is now the dominant treatment approach and has replaced open surgical repair, which is associated with high mor-
From the Second Department of Clinical Radiology, Medical University of Warsaw, Banacha 1A, Warsaw 02-097, Poland. Received July 15, 2015; final revision received June 29, 2016; accepted July 8, 2016. Address correspondence to M.W.; E-mail: [email protected] M.W. is a paid speaker and trainer for Covidien (Dublin, Ireland). R.M. is a paid proctor and trainer for Covidien. O.R. is a paid proctor for Medtronic (Dublin, Ireland). Neither of the other authors has identified a conflict of interest. & SIR, 2016 J Vasc Interv Radiol 2016; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2016.07.007
tality rates (1). When combined with optimal medical treatment, most patients will benefit from this treatment in cases of aortic remodeling, false-lumen (FL) thrombosis (FLT), and stable aortic diameters (2,3). Although TEVAR has proven beneficial in aortic remodeling in the thoracic region adjacent to the endograft, further concern remains regarding the suprarenal and infrarenal aorta. Recent studies (4) have shown that excluding only the primary entry tear in the thoracic aorta may fail to induce thrombosis of the abdominal aortic FL because of persisting distal entry tears at this level. Partial FLT, on the contrary, is directly related to FL aneurysmal dilation and an increased risk of rupture (5,6). FLT is the ideal endpoint of therapy, as it is associated with better long-term prognosis; however, it is rarely achieved with medical treatment alone, and intervention is most
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often required to repair the dissection and promote aortic remodeling (7,8). The aim of the present study is to evaluate the efficacy and clinical outcomes of ancillary endovascular procedures in promoting FLT and preventing aortic dilation in patients after TEVAR for type B dissections.
MATERIALS AND METHODS Patient Population This retrospective single-center study was approved by the institutional review board, which waived the need for individual patient consent. Between June 2006 and December 2014, 78 patients underwent TEVAR for acute or chronic type B aortic dissection with delayed thoracic aortic dilation. Among these, during their postTEVAR follow-up, 15 patients (19%; 12 men and three women; mean age, 59.6 y) had progressive increase in FL diameter in the aorta below the implanted endograft, requiring ancillary endovascular procedures to prevent further aneurysmal expansion and attempt to achieve FLT. Five patients (33.3%) had TEVAR in an acute setting, and 10 (66.6%) had been previously treated for chronic type B dissection. Patient comorbidities are presented in Table 1.
Imaging Protocol The standard imaging protocol after TEVAR was computed tomographic (CT) angiography performed 6 months after all ancillary interventions. In cases that did not require further intervention, a 12-month follow-up interval was established. In patients in whom an increase of the aortic diameter greater than 3 mm (considered to represent FL expansion) was observed, another examination was scheduled after 6 months. CT angiography of the entire aorta, from the proximal supraaortic vessels to the common femoral arteries, was performed on a 16-row and later on a 64-row multidetector scanner (LightSpeed or Optima 660; GE Medical Systems, FairTable 1 . Patient Comorbidities and Indications for TEVAR (N ¼ 15) Comorbidity Risk Factor
Incidence
Hypertension
14 (93)
CAD Diabetes mellitus
11 (73) 6 (40)
Smoking (current or past)
11 (73)
Hypercholesterolemia Previous stroke
7 (47) 3 (20)
Cocaine abuse
1 (7)
Connective tissue disease (Marfan, Ehlers–Danlos) Renal insufficiency
0 2 (13)
Chronic obstructive pulmonary disease
3 (20)
Note–Values in parentheses are percentages. CAD ¼ coronary artery disease; TEVAR ¼ thoracic endovascular aneurysm repair.
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field, Connecticut) with a reconstruction increment of 1.25 mm. Arterial- and delayed-phase images were obtained to determine the status of the FL (ie, patent or thrombosed).
Image Analysis CT angiographic imaging was used to assess new distal entry tears between the true lumens and FLs. Changes in aortic diameter and FL status were compared at the following seven levels: left subclavian artery, carina, level of the mitral valve, celiac trunk, uppermost renal artery, and largest diameters of the infrarenal aorta and common iliac arteries. The status of the FL was classified as total thrombosis if no flow was present, as partial thrombosis if flow and thrombus were present, and as patent if only flow was present. Changes in aortic diameters between the initiation of ancillary therapies and the achievement of total FLT or stabilization of aortic diameter were calculated using base measurements obtained from axial CTA image analysis on a Syngo MMWP workstation (Siemens Medical Solutions, Erlangen, Germany).
Endovascular Procedures The intent to treat was based on observed dilation of the FL by more than 5 mm per year with persistent turbulent flow and hyperperfusion of the FL on follow-up. Excluded from the study were patients with a ruptured FL and patients with organ malperfusion as a result of dissection. Mean maximum aortic diameter at the time of initial ancillary treatment was 47.4 mm (range, 34–63 mm). Collected imaging data were used to determine remaining dominant entry tears after TEVAR. Ancillary techniques to close these tears were used in a single stage or sequentially, but always relied on initial selective occlusion of detached arterial ostia with covered peripheral stents (mainly the renal or superior mesenteric artery ostium). This technique was applied in all patients to occlude significant entry tears at the paravisceral level while retaining patency of the dissected visceral vessels. Remaining ancillary techniques included the following: (i) implantation of a vascular plug into a major proximal entry tear in the dissection flap was applied when there was direct communication between lumens, no important vessel was present, and direct occlusion could be performed; (ii) implantation of a straight or bifurcated endograft in the abdominal aorta or iliac arteries was used when proximal visceral entry tears were already eliminated to occlude the remaining distal reentry tears tears from detached lumbar arteries and to induce remodeling of the infrarenal aorta; and (iii) embolization of an FL proximal or distal endoleak with ethylene vinyl alcohol copolymer (Onyx 34; Covidien, Dublin, Ireland) was performed as a last resort in cases in which an entry tear remained but could not be treated with the other described methods. To avoid nontarget embolization,
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detachable coils (Concerto; Covidien) were used as a scaffold for the liquid embolic agent. All ancillary procedures were performed percutaneously through the common femoral arteries or left axillary artery under local anesthesia in the interventional radiology suite. Stent grafts and iliac limb extensions were implanted with a surgical cutdown through the common femoral arteries under epidural anesthesia in the surgical operating theater. When occluding entry tears in the renal or superior mesenteric artery, cannulation of the detached ostium in the FL and then the true lumen of the artery was performed. Next, a peripheral stent graft (Advanta V12 [Atrium, Hudson, New Hampshire] or VIABAHN [W.L. Gore & Associates, Flagstaff, Arizona]) was deployed across both orifices, creating a connection between the artery and the true lumen while excluding a major distal entry tear at this level (Fig 1). In the later cases, the balloon-expandable peripheral stent graft (Advanta V12; Atrium) was reinforced with a selfexpanding nitinol stent (EverFlexþ; Covidien) to prevent kinking. In two cases, the FL in the thoracic aorta was cannulated through an intimal defect in the true lumen arising from a detached ostia of an intercostal artery, and a self-expanding stent (EverFlexþ; Covidien) was expanded in the dissection flap orifice, between the two lumens. Inside this stent, an AMPLATZER Vascular Plug type 2 (St. Jude Medical, St. Paul, Minnesota) was deployed to exclude the distal entry tear (Fig 2). The stent was used for positioning and as a scaffold to accommodate a large 10-mm AMPLATZER Vascular Plug type 2 because a smaller plug would not occlude the tear. The technique of occlusion of distal reentry tears in the abdominal aorta with a bifurcated endograft, endograft limb, and covered balloon-expandable stent or selfexpanding aortic stent did not differ significantly from standard everyday techniques of endovascular aortic
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repair. In patients in whom the previously mentioned techniques did not stabilize FL expansion, the perfused portion of the FL was embolized with ethylene vinyl alcohol copolymer (Onyx 34; Covidien). This technique was performed only when it was assumed that a single untreated entry tear remained that was causing local hyperperfusion and progressive growth of the FL. After angiographically ensuring that the blood supply to the spinal cord would not be affected, a dimethyl sulfoxide– compatible microcatheter (Rebar-18; Covidien) was introduced into the FL, and ethylene vinyl alcohol copolymer (Onyx 34; Covidien) was applied over a detachable coil scaffold (Concerto; Covidien) in a continuous manner until occlusion of the entire FL was perceived under angiographic control (Fig 3). Ethylene vinyl alcohol copolymer (Onyx 34; Covidien) was chosen in these lastresort situations as a controllable liquid embolic agent with a documented history of efficacy in the treatment of endoleaks after endovascular aortic repair. Postprocedural antiplatelet therapy in all patients consisted of 75 mg of acetylsalicylic acid. Patients were followed up with CT angiography 6 months after each ancillary intervention. If the FL diameter increase was persistent, further ancillary interventions were planned. Statistical analysis was performed by using SPSS software (version 20.0; SPSS, Chicago, Illinois). Estimated survival curves were calculated on the basis of the Kaplan–Meier estimate and are presented as life tables.
RESULTS The mean follow-up time between the first ancillary intervention after TEVAR and the last imaging study was 43.8 months (range, 8 d to 86.8 mo), with a 0% inhospital mortality rate. Estimated overall survival rates were 93.3%, 86.6%, and 77% at 12, 24, and 48 months,
Figure 1. Implantation of a covered peripheral stent at the level of the detached renal artery ostium. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrowhead) in the detached renal artery. (b) A covered stent (VIABAHN; W.L. Gore & Associates; arrowhead) was implanted connecting the true aortic lumen with the renal artery, and (c) control angiography shows perfusion of the right kidney from the true lumen via the implanted covered stent (arrowhead), with no leakage to the FL.
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Figure 2. Implantation of a vascular plug into a major proximal entry tear in the dissection flap. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrowhead) in the dissection flap at the level of the thoracic aorta. (b) A self-expanding stent (EverFlexþ; Covidien; arrowhead) was implanted through the distal entry tear, and (c) an AMPLATZER Vascular Plug type 2 (St. Jude Medical; arrow) was implanted into the stent (arrowhead) to eliminate flow into the FL. (d) Control angiography showing full perfusion of the true lumen with no leakage into the FL.
respectively (Fig 4). Three deaths occurred (20%), of which one was dissection-related at 40 months. One patient was lost to follow-up. All patients presented with a single FL. Mean number of entry tears per patient was 2.6 (range, 1–4). Among 15 consecutive patients undergoing ancillary procedures after TEVAR, 11 (73%) had more than one procedure performed before a stable aortic diameter could be achieved on follow-up. Patient data showing treated entry tears and FL patency/ thrombosis are presented in Table 2. The intended technical success was achieved in all cases except one in which it was impossible to introduce a covered stent into the celiac trunk. Completion angiography revealed patent main branch vessels with
minimal persistent flow into the FL at the level of attempted sealing. The first death, considered to be dissection-related, occurred 40 months after the last ancillary procedure. A review of CT angiographic images revealed misinterpreted hyperperfusion of the FL from the remaining proximal entry tear with minimal but present increases in FL between consecutive studies leading to rupture. The last recorded follow-up data for the second patient who died is from 8 months after implantation of a covered stent into the superior mesenteric artery. On follow-up CT angiography, a slight increase (13%) in the partially thrombosed FL at the level of the celiac axis was observed, whereas the remainder of the FL was thrombosed. A telephone
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Figure 3. Embolization of an FL proximal or distal endoleak with ethylene vinyl alcohol copolymer. (a) CT angiogram shows perfusion into the FL from a distal entry tear (arrow) in the dissection flap at the level of the visceral arteries. (b) Control angiography shows a single pair of lumbar arteries draining the perfused pouch (arrowheads) in the FL. (c) Control angiogram shows ethylene alcohol copolymer (Onyx 34; Covidien) over a detachable coil scaffolding (Concerto; Covidien) filling the pouch completely (arrowheads) without nontarget embolization.
level of the celiac trunk using the femoral access, and another attempt will still have to be made from another access route.
DISCUSSION
Figure 4. Life table plotting cumulative survival against time (in months) between the first intervention and the last imaging study in patients who have undergone ancillary intervention after TEVAR.
inquiry revealed that the patient died suddenly at 14 months after treatment for this study, after a reported myocardial infarction. Finally, the third patient who died was initially lost to follow-up (3 mo after repeat intervention) and did not respond to our telephone and mail inquiries. We assume that his date of death was between 3 and 12 months and include this in survival estimate calculations. No postprocedural spinal cord ischemia was observed. Among the surviving 12 patients in the series, eight (67%) had total FLT during the follow-up period. Within this group, seven patients had total FLT in a relatively short period of time after the final procedure, between 6 days and 5 months. In a single patient, total FLT occurred 73 months after the last procedure. Three patients had partial FLT at two and three levels of the abdominal aorta with stable aortic diameters at 7, 11, and 27 months of follow-up. The remaining patient had an increase in aortic diameter at the suprarenal level of the dissected aorta on 21-month follow-up. A failed attempt was made to seal a remaining entry tear at the
Aortic remodeling after TEVAR in type B dissections is predominantly seen in the thoracic aorta, and mostly at the level of the previously implanted endograft (3). The same does not always occur in the abdominal aorta, especially in complicated dissections. Several authors have already reported this concern. Bockler et al, in their series of 50 patients undergoing TEVAR, observed total or partial FLT in 60% of patients and severe abdominal aortic expansion (4 50 mm) in five patients (10%) (9). Similar observations on the expansion of the abdominal aorta have been made by Resch et al (10) with data from a Swedish multicenter study in which 16% of patients exhibited expansion in the uncovered portion of the descending aorta, and by Gaxotte et al (11), who noted that complete FLT resulted in decreased aortic diameters, but chronic expansion of the dissected uncovered aorta continued (11,12). Although the incidence of expansion of the uncovered aorta on follow-up was reported not to exceed 20% after TEVAR, the lack of FLT, often considered as an endpoint for therapeutic success, is still an ongoing weak point of TEVAR in the treatment of type B dissections (13). Aortic segments with partial FLT have a significantly higher annual aortic growth rate, which may lead to rupture, whereas patients with total FLT and aortic remodeling have a better long-term prognosis, making it a necessity to establish proven ancillary therapies that will halt thoracoabdominal degeneration and promote complete thrombosis of the FL (14,15). Several minimally invasive techniques have already been proposed to
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Aorta
TEVAR
No. of
Extent Follow-up Duration
Pt. No Size (mm) Setting
TA
CA
SMA
RRA
LRA
RIA
LIA
1
38
Acute
TL
TL
TL
Covered stent
TL
Covered stent
Covered Stent
3
Total
2
41
Chronic
TL
TL
TL
TL
Covered stent
TL
TL
1
Patent
0.07 (Dead)
3 4
36 55
Acute Aortic SEMS Chronic TL
FL TL
TL Covered stent
TL TL
Covered stent TL
TL –
TL –
2 1
Partial Total
26.70 (Alive) 8.73 (Dead)
5 6
43 58
Chronic Chronic
TL TL
TL TL
3 3
Patent Total
40.97 (Dead) 86.83 (Alive)
7
52
Chronic
TL
TL
TL
TL
Covered stent
8 9
52 49
Acute Chronic
AVP TL
TL TL
TL TL
Covered stent Covered stent
TL TL
10
48
Chronic
AVP
TL
FL Onyx
Covered stent
TL
11 12
37 56
Acute Chronic
TL TL
TL TL
TL TL
TL TL
13
34
Acute
TL
Covered stent
14 15
63 49
Chronic Chronic
TL –
FL Onyx FL Onyx
TL
Covered stent Covered stent Covered stent TL
FL Covered stent EVAR (straight) TL
TL
TL
(mo)*/Outcome 41.33 (Alive)
Aortic SEMS
2
Total
52.96 (Alive)
Covered stent Aortic SEMS
2 2
Total Total
35.06 (Alive) 52.50 (Alive)
EVAR (bifurcated)
4
Partial
61.10 (Alive)
2 1
Partial Total
59.13 (Alive) 73.50 (Alive)
–
1
Total
27.33 (Alive)
EVAR (bifurcated) EVAR (bifurcated)
4 3
Total Patent
18.50 (Alive) 58.40 (Alive)
TL Covered stent Aortic SEMS, LIA covered stent Covered stent TL – TL
Covered stent Covered stent TL – TL Covered stent
Interventions of FLT
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Table 2 . Procedure-Related Data and Status of FL
AVP ¼ AMPLATZER Vascular Plug; CA ¼ celiac axis; EVAR ¼ endovascular abdominal aortic repair; FL ¼ false lumen; LIA ¼ left iliac artery; LRA ¼ left renal artery; RIA ¼ right iliac artery; RRA ¼ right renal artery; SMA ¼ superior mesenteric artery; TL ¼ true lumen; SEMS ¼ self-expanding metal stent (Zenith Dissection Endovascular System [Cook, Bloomington, Indiana] or Sinus-XL stent [OptiMed, Ettlingen, Germany]); TA ¼ thoracic aorta; TEVAR ¼ thoracic endovascular aneurysm repair. *Follow-up time between the first ancillary intervention after TEVAR and the last imaging study.
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address this problem, the most successful being the proposals by Oikonomou et al (16) to use fenestrated/ branched TEVAR to reestablish the true lumen and exclude the FL. Employing this technique made it possible to achieve an FLT rate of 88.2% at 12 months in a group of 31 patients. Another technique is the technique proposed by Hofferberth et al (17) consisting of coil and glue embolization of the false channel in an attempt to repair small intimal defects. In a mean follow-up of 63 months, this technique allowed for total FLT in two of 10 patients, with the remaining patients having partial FLT at the level of the abdominal aorta. Eriksson et al (18) reported the use of peripheral covered stents in the treatment of expanding FL in a subgroup of four patients presenting with complicated type B dissections and achieved a 50% total FLT rate (18). On the contrary, a different approach, the use of the “PETTICOAT (provisional extension to induce complete attachment) technique” employing a bare stent as an extension from the thoracic endograft throughout the entire abdominal aorta, failed to limit FL expansion in the abdominal segment, as reported by Melissano et al (19). The ancillary techniques presented in the present study, mainly based on occluding entry tears with covered peripheral stents, seem simpler than the previously described techniques while still stabilizing aortic expansion in 92% of surviving patients on long-term follow-up. With an in-hospital mortality rate of 0%, compared with the fairly high 9.6% mortality rate reported by Oikonomou et al (16), albeit with a lower rate of total FLT (88% vs 67%), these sequentially performed minimally invasive techniques could be useful in patients with comorbidities who would otherwise be poor candidates for fenestrated/ branched TEVAR. The application of these minimally invasive techniques involves an astute observation of the dissection flap with its entry tears, especially in cases of high flow, arising from the detached ostia of major abdominal vessels. After TEVAR and closing of the primary entry tear, the FL is predominantly perfused by a normotensive inflow through the detached abdominal arterial ostia and the outflow through the iliac/hypogastric artery, leading to pressure equilibrium and stable FL in the majority of patients (80%–90%) receiving hypotensive therapy after TEVAR (20). The remaining 10%–20% patients in whom such a pressure equilibrium cannot be naturally established as a result of impaired outflow from the FL, total FLT—or at least stability of the aortic expansion— can be achieved by excluding the remaining major entry tears. In the present study, effective depressurization of the FL was achieved in 92% of 12 surviving patients (73% overall), with total FLT in eight (67%) and partial FLT with stable aortic diameter in three (25%). On the contrary, in a retrospective analysis of the present study, in the patient who died at 40 months of follow-up, we inadvertently hyperpressurized the FL at the aortic
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bifurcation by excluding the predominant distal outflow tract through the iliac artery. This was a significant technical planning error and a reminder that these patients should be under special scrutiny during follow-up. The one remaining patient had an increase in the diameter of the FL at the level of the thoracic and suprarenal aorta at 21 months’ follow-up. All diameter increases were associated with partial FLT, a known predictor of increased annual aortic growth rate as well as an independent predictor of postdischarge mortality in these patients (21). These are problems that will have to be addressed in the near future by employing further ancillary methods such as polymer embolization (Onyx 34; Covidien) to ensure full thrombosis of the FL. In cases in which we could limit the expansion of the FL in the abdominal aorta, attempts were made to fill the remaining FL entirely with ethylene vinyl alcohol copolymer. In two cases in which relatively small quantities were needed to fill the FL, this approach was successful. In one patient in whom we attempted to fill the majority of the FL, this method proved unsuccessful, with ethylene vinyl alcohol copolymer layering at the dorsal part of the FL aorta and leaving the ventral part perfused from the still-patent reentry tears. The FL slowed down in expansion on 6-month follow-up CT angiography, but the lack of FLT may still pose a problem in the future. The observations made in the present study are limited by its retrospective nature, the small sample size, lack of randomization, inhomogeneity of dissections among the type B subtype, use of varied endovascular techniques, and patients lost without appropriate follow-up. In conclusion, properly thought out and planned selective exclusion of the remaining post-TEVAR distal entry tears at the level of the abdominal aorta appear to represent a feasible approach to promote FLT. In the majority of patients, it can effectively stabilize thoracoabdominal aortic expansion and potentially reduce mortality in these patients. Accurate follow-up of these patients is essential, as they will rarely directly benefit from a single-stage procedure. In these cases, additional measures may have to be undertaken to prevent further FL dilation, with polymer embolization considered a last-resort endovascular treatment.
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