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Outcomes of Endovascular Repair ofAscending Aortic Dissection in PatientsUnsuitable for Direct Surgical Repair

Zhenjiang Li, MD, Qingsheng Lu, MD, Rui Feng, MD, Jian Zhou, MD, Zhiqing Zhao, MD, Junmin Bao, MD,Xiang Feng, MD, Jiaxuan Feng, MD, Yifei Pei, MD, Chao Song, MD, Zaiping Jing, MD, PHD

ABSTRACT

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BACKGROUND Stent grafting is a therapeutic option for patients who are unable to undergo urgent surgical repair of

ascending aortic dissections. However, follow-up regarding outcomes is limited.

OBJECTIVES This study reports mid-term outcomes with endovascular repair for ascending aortic dissections in

patients deemed high risk for open repair.

METHODS Between May 1, 2009 and January 31, 2011, 15 ascending aortic dissection patients (ages 45 to 78 years)

ineligible for direct surgical repair underwent endovascular repair (1 acute dissection, 7 subacute dissections, and

7 chronic dissections) and were closely followed up for a median of 72 months (range 61 to 81 months).

RESULTS The mean interval between aortic dissection onset and treatment was 25.5 (range 6 to 353) days. Technical

success was achieved in all patients. No major morbidity or deaths occurred perioperatively. During the follow-up period,

there were no deaths, 8 complications occurred, and there were 4 reinterventions. A new dissection in the aortic arch was

treated with a branched endograft. One patient developed retrograde aortic dissection and a left ventricular pseudoa-

neurysm was successfully treated with open surgery. One cardiovascular ischemia was treated with stenting and

1 supraventricular tachycardia was treated with radiofrequency ablation. Other morbidities included perigraft endoleak,

a bird-beak sign, a temporary pericardial effusion, and a left kidney atrophy. Significant enlargements of true lumens

and shrinkage of false lumens and overall thoracic aorta were observed at 12 months. No significant changes were

detected subsequently. Minimal impact on aortic valve function was recorded over time.

CONCLUSIONS Our results with the novel endovascular procedure appear acceptable. Additional evidence and

studies with larger sample size and longer follow-up are needed to support the durability of this new technique.

(J Am Coll Cardiol 2016;68:1944–54) © 2016 by the American College of Cardiology Foundation.

S urgical replacement of the ascending aorta hasbeen the gold standard treatment for patientswith ascending aortic dissection (AAD). Despite

increased understanding of the pathophysiology,improved surgical techniques and devices, andadvances in anesthetic management, improvementin overall surgical outcomes remains modest, with amortality of 10% to 35% (1–3). Furthermore, approxi-mately 10% to 30% of patients with AAD are deemedinoperable due to advanced age, severe comorbidity,

m the Department of Vascular Surgery, Changhai Hospital, Second Militar

National Natural Science Foundations of China (grants 81330034, 8127

ining Plan (grants XYQ2013087). The authors have reported that they ha

per to disclose. Drs. Li, Lu, and Feng contributed equally to this work.

nuscript received March 5, 2016; revised manuscript received June 21, 20

or hemodynamic instability (4,5). These patients weredeemed high-risk candidates for conventional openrepair and only received medical treatment with ahigh in-hospital mortality of 58% (6).

Minimally invasive endovascular techniques havebeen explored in an attempt to improve the prognosisof patients at high surgical risk. Initial findings fromsporadic reports showed acceptable early results,indicating the feasibility and preliminary efficacy ofendovascular repair despite complications associated

y Medical University, Shanghai, China. Supported by

0386, 81273522), and the Shanghai Medical Talents

ve no relationships relevant to the contents of this

16, accepted July 22, 2016.

SEE PAGE 1955

AB BR E V I A T I O N S

AND ACRONYM S

AAD = ascending aortic

dissection

CTA = computed tomography

angiography

LV = left ventricle

RTAD = retrograde type A

dissection

J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6 Li et al.N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4 Endovascular Repair of Ascending Aortic Dissection

1945

with procedural cerebral ischemia, progressive aorticvalvular insufficiency, and cardiac insufficiency (7–9).One computed tomography-based study (10) indi-cated that about 30% of patients with type A dissec-tion could be appropriate candidates for endovascularrepair. A larger number of patients might benefit fromthis less invasive approach if the safety, efficacy, anddurability are established.

However, limited outcomes prompted betterevaluation of this emerging therapeutic modality (9).We offered endovascular treatment to 15 AAD pa-tients unsuitable for surgery in our center betweenMay 1, 2009 and January 31, 2011 and demonstratedacceptable early outcomes (11). To gain better insightinto the safety and durability of the endovascularprocedure, we followed the initial patient cohortcontinuously and analyzed the clinical outcomes andimpact on aortic remodeling and aortic valve func-tion over a mean follow-up period of 72 (range 61 to81) months.

METHODS

PATIENTS. Between May 1, 2009 and January 31,2011, 183 patients with type A aortic dissection wereadmitted to our hospital. An established clinicaltreatment process was implemented, and open sur-gery was considered first. One hundred forty-twopatients entered the cardiothoracic center for directsurgical repair. For patients with multiple high sur-gical risk factors, a multidisciplinary consultationboard consisting of cardiac surgeons, cardiologists,vascular surgeons, and anesthetists reviewed all thecases to evaluate the operating risk. A set of criteriawas proposed as an integrated strategy to identifypoor candidates for open surgery, including advancedage (>70 years), an American Society of Anesthesiol-ogists Classification of IV or more, New York HeartAssociation functional class III or worse, previoussternotomy, or dysfunction of other important organsystems (i.e., severe chronic obstructive pulmonarydisease, renal or hepatic insufficiency, stroke). Ofnote, a patient was not judged high risk and dis-qualified from a surgical procedure on the sole basisof advanced age or other single risk factor. Weconsidered all the items comprehensively and iden-tified high-risk patients on an individual basisknowing details of the risk features and specificconditions for each patient. Patients deemed inoper-able (n ¼ 41) were transferred to our vascular centerfor further assessment and possible endovasculartreatment. Inclusion criteria were entry tear locatedin the mid-third of ascending aorta and length ofproximal and distal aortic landing zone >20 mm.

Exclusion criteria were involvement of coro-nary artery orifice, acute myocardial infarc-tion, signs of cardiac tamponade, or severeaortic regurgitation (grade 3 or 4) docu-mented by echocardiography, history ofpotentially life-threatening ventriculararrhythmia, and connective tissue disorders(Marfan or Ehlers Danlos syndrome). Patientswho refused or were excluded for surgical orendovascular repair were treated medically.

Fifteen patients were treated using endovasculartechniques. The incidence of endovascular proced-ures was 8.2% (15 of 183) for all type A patientsreferred to our hospital and 36.6% (15 of 41) for allpatients unfit for open surgery. All endovascularprocedures were approved by our internal reviewboard, and all patients provided informed consent.

ENDOVASCULAR PROCEUDRE. The endovascularprocedures have been described previously (11).Cook Zenith TX2 Pro-Form extension stent grafts(Cook, Bloomington, Indiana), commercially avail-able thoracic endografts, were used. They are madeof full-thickness woven polyester fabric sewn to self-expanding stainless steel Cook-Z stents with braidedpolyester and monofilament polypropylene suture.This graft has the available dimensions matchedwith that of the ascending aorta (diameter varyingfrom 28 mm to 42 mm and length ranging from77 to 81 mm), which is the key factor. The ZenithTX2 Pro-Form is a modified version of TX2, withimproved device and delivery system. The stentgraft retained the key features of the original TX2and provides adequate radial strength and force withappropriate oversize, although it does not manifestbest compliance. Furthermore, the design of thestent graft without proximal bare springs was rec-ommended at our center for cases for which therewas concern of compromising the aortic valve. Themodified deployment system of this new versionholding the proximal end closed in a trifold fashionwith trigger wires maintains the proximal stentparallel to the aortic inner curvature duringdeployment and allows micro-readjustments whenthe stent graft is deployed partially. This designfacilitates accurate deployment, alignment, andapposition of the graft in the ascending aorta. Thisgraft conforms adequately in curved aorta (12). Sizeselection of endograft was based on the ascendingaortic diameter proximal to the tear, with about 20%enlargement in the true lumen in case of chronicpathologies to decrease the risk of late migration,

TABLE 1 Patient Characteristics

%

Male 80.0 (12/15)

Age, yrs 65.0 � 12.1

Risk of open surgery

Advanced age 38.9 (7/18)

Severe COPD 16.7 (3/18)

Cardiac dysfunction 11.1 (2/18)

Renal insufficiency 11.1 (2/18)

Others* 22.2 (4/18)

Classification

DeBakey type I 93.3 (14/15)

DeBakey type II 6.7 (1/15)

Dissection range

Involving aortic root 20.0 (3/15)

Involving coronary artery 0.0

Confined to ascending aorta 6.7 (1/15)

Involving descending aorta 6.7 (1/15)

Involving abdominal aorta 86.7 (13/15)

Location of entry tear

Length from STJ to IA, mm 92.9 � 12.5

Length from STJ to tear, mm 50.4 � 22.7

Length from tear to IA, mm 42.5 � 17.6

Longitudinal length of tear, mm 8.7 � 7.5

Aortic regurgitation

Mild, grade 1 86.7 (13/15)

Moderate, grade 2 13.3 (2/15)

Severe, grade 3 or 4 0.0

Values are % (n/N) or mean � SD. *Others: 1 case with hepatic inadequacy (post-hepatitic cirrhosis, Child-Pugh classification grade B) and airway obstruction, 1with previous thoracotomy, and 1 stroke.

COPD ¼ chronic obstructive pulmonary disease; IA ¼ innominate artery; STJ ¼sinotubular junction.

Li et al. J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6

Endovascular Repair of Ascending Aortic Dissection N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4

1946

and about 10% for acute lesions with fragile aorticwalls. Diameters of major axis in the cross sectionperpendicular to centerline of flow on 3-dimensionalreconstructed image (13,14) were selected as theestimated value of aortic diameter.

General anesthesia was used in all cases. Endog-rafts were advanced into the ascending aorta over theextra stiff guidewire through femoral access. In allcases, the endograft was placed in the very proximalascending aorta just distal to the orifices of thecoronary arteries for exclusion of the entry tearand ensuring patency of the coronary and brachio-cephalic arteries. Complete details of the procedureincluding position and deployment of endograft,removal of the delivery system, have been describedpreviously (11).

FOLLOW-UP. Follow-up consisted of physical exam-ination, echocardiography, computed tomographyangiography (CTA) scans and documentation of mor-tality and morbidity at 6 months post-procedure andannually thereafter. Three-dimensional TeraReconreconstructions based on follow-up CTA were usedfor measurements. Overall aortic, true lumen, andfalse lumen diameters were measured at the level ofsinotubular junction, the ostium of the innominateartery, the point of maximum ascending aorticdiameter, and the ostium of the left subclavian artery.Status of patency or thrombosis of the false lumenwas assessed using delayed phase imaging. Echocar-diography was used to evaluate cardiac and valvularfunction. Additional CTA examinations were con-ducted if patients manifested any new symptoms orsigns of adverse events.

STATISTICAL ANALYSIS. Continuous variables werereported as mean � SD. Skewed variables were sum-marized as median and range. The diameters werecompared using 2-sided paired sample Student t tests.A p value <0.05 was considered significant. SPSSsoftware version 19.0 (SPSS, Inc., Chicago, Illinois)was used for all analyses.

RESULTS

The baseline demographics, clinical characteristics,and risks for open surgery in the 15 patients under-going endovascular repair are summarized in Table 1.The mean age of the patients was 65.0 � 12.1 years(range 45 to 78 years). Eight patients presented withmultiple severe comorbidities or previous sternot-omy, although they were younger than 70 years andwere considered at high surgical risk and treatedwith endovascular procedures. Men constituted 80%of all the patients. The median time interval frominitial dissection to treatment was 25.5 days (range

6 to 353 days). Based on temporal IRAD (Interna-tional Registry of Acute Aortic Dissection) classifi-cation, 1 patient was found in acute phase (2 to 7days), 7 patients in subacute stage (8 to 30 days),and 7 patients in chronic condition (>30 days),whereas no patient was in hyperacute phase (0 to 24h) (15). It is important to note that these 15 patientswere treated medically for a variety of reasons spe-cific to the hospital where they initially soughttreatment and survived the initial phase of acuteaortic dissection. They came because of persistentsymptoms or anatomic findings that warrantedtherapeutic intervention.

All the entry tears were located in the middleportion of the ascending aorta according to pre-operative CT scans and intraoperative measure-ment. Among these 15 patients, 14 patients wereDeBakey type I dissections and one was a type IIdissection. Three patients were diagnosed withaortic dissection that proximally extended partiallyinto the aortic root but without coronary artery

TABLE 2 Intraoperative Details and In-Hospital, Follow-Up Outcomes

Intraoperative details

Operation time, min 128.6 � 26.2

Stent graft diameter/proximallanding zone diameter, %

118.7 � 6.3

Stent graft diameter/distallanding zone diameter, %

107.9 � 8.2

Stent graft length, mm 78.9 � 2.0

Stent graft length/ascendingaorta length, greatercurvature, %

84.1 � 9.3

In-hospital outcomes

ICU stay, days 3.3 � 1.0

Hospitalization time, days 9.4 � 2.5

In-hospital complication 2 (arrhythmia)

In-hospital mortality 0

Follow-up outcomes

Follow-up time, months 62 (52–71)

Follow-up complications 8 (new dissection, cardiovascular ischemia,supraventricular tachycardia, RTAD andleft ventricular pseudoaneurysm,temporary pericardial effusion, left kidneyatrophy perigraft endoleak bird-beak sign)

Reintervention 4 (branched stent graft deployment, coronarystenting, radiofrequency ablation,open surgery)

Follow-up mortality 0

Values are mean � SD, median (range), or n.

ICU ¼ intensive care unit; RTAD ¼ retrograde type A aortic dissection.

J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6 Li et al.N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4 Endovascular Repair of Ascending Aortic Dissection

1947

involvement. Despite that stent grafting should beinitiated at the level of “normal” aorta, endograftrepair was still attempted in these 3 patients toavoid the progress of the vital pathologies, whichwill not heal without mechanical exclusion.Although satisfactory outcomes may not be ex-pected, endovascular therapy at least serves as abridge to definitive open repair, if needed, in laterstages. The dissection lesion was confined to theascending aorta in 1 patient. Antegrade extensionto descending aorta was found in 1 patient andpropagation to abdominal aorta occurred in 13patients (Table 1).

The intraoperative details are listed in Table 2. Themean endovascular procedure time was 128.6 � 26.2min. Themean ratio of the diameter of the stent graft tothat of the aorta (proximal to the tear) was 118.7�6.3%.Average stent graft coverage of the ascending aortawas 84.1 � 9.3%.

CLINICAL OUTCOMES. Table 2 summarizes the peri-operative and follow-up outcomes. Patients werefollowed for a median of 72 months (range 61 to 81months). No deaths occurred during the follow-up,but 8 major morbidities were recorded. A single newdissection occurred in the aortic arch distal to theascending aortic endograft at 3 months and was suc-cessfully treated using a customized branched stentgraft (Figure 1). The other patient developedretrograde type A aortic dissection (RTAD) andpotentially procedure-related left ventricular (LV)pseudoaneurysm at 29 months post-operatively. Hewas converted to surgical repair and successfullyrecovered following replacement of ascending aortaand proximal arch and linear closure of the LVpseudoaneurysm.

One patient manifested severe stenosis of leftanterior descending artery with myocardial ischemiasymptoms and was relieved after coronary stenting.One patient experienced supraventricular tachy-cardia at 37 months and was treated with percuta-neous radiofrequency ablation. Another patientwith temporary pericardial effusion recoveredspontaneously with conservative treatment. The CTscan showed the stent graft in the right place. Leftkidney atrophy was detected in 1 patient at 59months with slightly elevated serum creatinine of143 mmol/l. The patient had undergone left renalartery stenting to restore the blood flow compro-mised by dissection.

One patient developed perigraft endoleak withoutdilation of aortic segment at 71 months. The limitedperigraft flow was traced to the gap between thedistal portion of the endograft and lesser curvature of

proximal aortic arch leading to unsatisfactory sealing.In the absence of any contrast material in the falselumen and absence of symptoms, medical treatmentand vigilant monitor was prescribed. Another patientdeveloped a bird-beak configuration at the distallanding site at 36 months (Figure 2) without anysymptoms. The retrograde flow into the wedge-shaped space was limited without any adverseevents. The configuration was stable until the lastfollow-up (Figure 2).

During follow-up, no migration of the stent graftsor compromised coronary arteries and supra-archvessels were detected. No patient suffered fromneurological complication such as transient ischemicattack, spinal cord ischemia, or stroke.

AORTIC REMODELING. Complete thrombosis of thefalse lumen of the ascending aorta was noted in allthe 14 DeBakey type I patients and remained stableduring the follow-up. Complete thrombosis of thefalse lumen of the descending aorta was noted in 11patients (11 of 14, 78.6%), and partial thrombosis wasnoted in 3 patients (3 of 14, 21.4%). The patient withDeBakey type II dissection was converted to opensurgery repair with ascending aorta replacement forRTAD and LV pseudoaneurysm, representing anaortic remodeling failure.

FIGURE 1 New Dissection in the Arch After Primary Endovascular Procedure

(A) Computed tomography angiography image showing new dissection in the aortic arch with compression of stented true lumen at 3 months. (B) The new entry tear

located in the proximal arch (arrow). (C) Aortography before endovascular reintervention showing patent false lumen. (D) Last follow-up computed tomography

angiography 3-dimensional construction image confirming thrombosis of the false lumen along the ascending aorta and patency of the stent in left common carotid

artery. (E) Computed tomography angiography image after reintervention revealing expansion of stented true lumen in ascending and descending aorta. (F) Completion

aortography showing complete exclusion of the entry tear using a branched stent graft with single fenestration.

Li et al. J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6

Endovascular Repair of Ascending Aortic Dissection N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4

1948

Changes in the mean diameter of the total aorta,true lumen, and false lumen were measured on thebasis of follow-up imaging, as shown in Table 3 andFigure 3. Notably, the DeBakey type II patient wasexcluded when analyzing the changes of ascendingaortic dimension due to replacement of dissectedascending aorta and was excluded when analyzingthe changes of descending aortic dimension with thelesions confined to ascending aorta. The total aorticdiameter significantly decreased at the levels ofmaximal ascending aorta and distal ascending aortawithin 12 months post-procedure. Trends indecreased diameter were also seen at the level ofproximal ascending aorta and proximal descendingaorta, although insignificant. During the subsequentfollow-up, the average diameters of total aorta

remained constant. Significant changes in size wereobserved in both true lumen and false lumen beforeendografting and at 12 months, indicating clearexpansion of the true lumen and shrinkage of thefalse lumen as a result of tear exclusion. Duringsubsequent follow-up, the diameters of true lumenand false lumen at all the levels measured did notchange significantly.

ECHOCARDIOGRAPHIC FINDINGS. The pre-operativeLV end-systolic diameter was 38.9 � 10.6 mm. Atthe current follow-up, the LV end-systolic diameterwas 42.1 � 5.4 mm (p ¼ 0.324). The LV ejection frac-tion was 53.6 � 2.5% pre-operatively and 52.5 � 2.1%(p ¼ 0.219) at the end of follow-up. The diameter ofthe sinotubular junction was 26.8 � 3.5 mm before

FIGURE 2 Bird-Beak Configuration During Follow-Up

(A) Computed tomography angiography revealing the entry tear in the middle of the ascending aorta and patent false lumen. (B) Completion

aortography showing exclusion of the tear in the ascending aorta with patent branch arteries after endovascular repair. (C) The 24-month

computed tomography angiography showing thrombosed false lumen and correctly positioned stent graft. (D) The 36-month computed to-

mography angiography showing bird-beak configuration. (E) The 62-month aortography showing stable configuration (black arrow) and patent

coronary arteries (white arrows).

J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6 Li et al.N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4 Endovascular Repair of Ascending Aortic Dissection

1949

procedure and the diameter was 27.6 � 3.7 mm(p ¼ 0.562) at the end of follow-up, indicating sta-bility of the diameters. As shown in Table 1, 13patients suffered from mild aortic regurgitation pre-operatively, whereas moderate aortic insufficiencywas detected in 2 patients with dissection extendingdown the root. Improvement in aortic insufficiencyfrom moderate to mild degree was seen in the 2patients before discharge. During follow-up, all the

patients manifested mild aortic insufficiency, despitethe slight reflux during diastolic period of echocar-diography, revealing the relatively normal function ofthe aortic valve. In 1 patient with pre-existing LVenlargement and moderate mitral valve regurgitationbefore procedure, the cardiac function remained sta-ble without continuous dilation of the LV and thereflux volume of mitral regurgitation remained at amild level of 7 ml.

TABLE 3 Changes of Diameters of the TL, FL, and TA at Different Measuring Levels

Diameter (mm)

Pre-Procedure 12 Months p Value* 36 Months p Value† End of Follow-Up p Value‡

TL

MAA 21.3 � 6.7 35.6 � 5.8 <0.001 37.0 � 5.5 0.518 37.7 � 5.3 0.734

PAA 24.5 � 7.5 32.6 � 5.7 0.004 34.5 � 4.8 0.349 35.7 � 4.3 0.492

DAA 32.7 � 4.8 36.2 � 3.8 0.042 36.8 � 3.5 0.668 37.7 � 3.2 0.484

PDA 28.3 � 2.9 30.0 � 3.6 0.011 31.3 � 3.72 0.356 31.6 � 3.3 0.823

FL

MAA 35.1 � 8.5 9.8 � 6.2 <0.001 8.95 � 5.7 0.709 8.13 � 5.9 0.711

PAA 25.8 � 7.9 13.1 � 6.1 <0.001 9.95 � 6.9 0.212 9.13 � 7.4 0.764

DAA 14.2 � 6.5 5.0 � 3.1 <0.001 3.25 � 2.1 0.092 3.17 � 2.2 0.922

PDA 11.8 � 4.2 5.1 � 3.2 <0.001 4.90 � 2.9 0.864 4.80 � 2.5 0.923

TA

MAA 56.4 � 6.7 45.8 � 5.3 <0.001 45.3 � 4.6 0.792 44.6 � 5.0 0.703

PAA 50.4 � 6.5 46.2 � 5.7 0.081 44.5 � 4.9 0.405 43.8 � 5.6 0.728

DAA 48.7 � 10.2 40.8 � 9.4 0.043 40.1 � 10.4 0.689 40.0 � 10.6 0.901

PDA 39.2 � 3.0 36.5 � 4.4 0.069 36.0 � 4.1 0.758 34.8 � 4.6 0.473

Values are mean � SD. *The p value refers to the change of diameters between pre-procedure and 12 months.†The p value refers to the change of diameters between 12 months and 36 months. ‡The p value refers to thechange of diameters between 36 months and the end of follow-up.

DAA ¼ distal ascending aorta; FL ¼ false lumen; MAA ¼ maximal ascending aorta; PAA ¼ proximal ascendingaorta; PDA ¼ proximal descending aorta; TA ¼ total aorta; TL ¼ true lumen.

Li et al. J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6

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1950

DISCUSSION

Dorros et al. (16) first treated AAD with endovasculartechnique via transseptal access in 2000. Endovas-cular repair of AAD was reported first in 2003 throughfemoral access (17). Since then, a number of isolatedstudies described stent grafting in the ascendingaorta in an emergency setting as a bridge or in anelective setting as an alternative for patients who hadbeen deemed inoperable. Current studies showedencouraging early outcomes and confirmed thefeasibility in selected patient cohorts despite majoradverse events (7–9,18). However, long-term out-comes of this novel therapeutic paradigm have notbeen reported adequately, and most available studiesreported results of follow-up <12 months (19,20).

Early mortality associated with endovascular repairfor AAD was acceptable ranging from 0% to 14%, asmost cases were treated in their acute phase(8,9,18,21), underlining the minimal physiologicimpact of endovascular procedure and indicating thepotential value of reducing the mortality in this high-risk patient cohort. In our study, the mortality ofperioperative and follow-up period was 0%. Thisalternative therapeuticmethod appears to increase thesurvival rate in selected patients and maintain themortality benefit for a long-term follow-up. The less-invasive nature of endovascular repair and rapidmobilization and recovery may contribute to this

survival benefit, which is associated with relativelylow rates of major procedural complications. In addi-tion, the thrombosed false lumen in type A aorticdissection was reported to be an indicator for survival(22). Therefore, early closure of the dissection entrytears using this approach and induced false lumenthrombosis may also help improve the long-term sur-vival, as compared with medical therapy (CentralIllustration). However, several biases may contributeto these good outcomes. All these patients were thosewho survived the initial phase with medicine alone,indicating the selection bias in the study. Meanwhile,the rate of acute AAD was rather low, with 7 chronicdissections in 15 patients, which showed an inherentsurvival bias.

Endoleaks are considered the Achilles heel ofendovascular procedures. In the endovascular treat-ment for type B aortic dissection, the mid-termendoleak rate was reported as high as 8.1% (22). Onthis basis, endografting in the ascending aorticsegment can be more likely to cause endoleaks, pre-dominantly type I (proximally or distally), which maypotentially lead to false lumen dilation and rupture.During operation, good seals were achieved withascending aortic stent graft in all patients, whereas asingle limited endoleak appeared during follow-up,resulting in a late endoleak rate of 6.7% (1 of 15).Endoleak formation was associated with a smallradius of curvature of arch and shortage of landingzone for stent graft (23). Therefore, the low rate ofearly endoleak in our study may benefit from strictpatient selection with proximal or distal landing zone>20 mm and entry tear in the middle part of ascendingaorta. However, the discrepancies of configurationbetween straight endograft and curved proximalaortic arch, the pulsatory motion of aorta and strike ofpulsatory blood flow may deteriorate the early benefitand result in perigraft endoleak and even endograftmigration in late phase. A bird-beak sign occurred atthe distal end of stent-graft in another patient at 36months, which may be attributed to dilation of distalascending aorta and significant proximal arch angletransformation as a result of aortic remodeling (24),underscoring the risk of incomplete endograft appo-sition to the aortic wall in late phase. To achievesustainable endograft conformance, assessment ofthe proximal arch angle was encouraged when con-firming the candidacy for endovascular treatment. Anew generation endograft matching the inner curva-ture of the distal ascending aorta and proximal archwas needed.

In the ascending aortic segment, close to theaortic valve, high aortic impulses cause significant

FIGURE 3 Changes in Mean Diameters of Aorta Through Follow-Up

70

60

50

40

30

20

10

0

60

50

40

30

20

10

0

70

60

50

40

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0

35

4550

40

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2025

1015

05

Preprocedure 12 months 36 months the end of FU Preprocedure 12 months 36 months the end of FU

Preprocedure 12 months 36 months the end of FUPreprocedure 12 months 36 months the end of FU

Maximal Ascending Aorta Proximal Ascending Aorta

Distal Ascending Aorta Proximal Descending Aorta

Total aorta

True lumen

False lumen

Total aortaTrue lumen

False lumen

Diam

eter

(mm

)Di

amet

er (m

m)

A B

C D

Line graphs showing the mean diameters of the total aorta, true lumen, and false lumen at the level of maximal ascending aorta (A), proximal ascending aorta (B), distal

ascending aorta (C), and proximal descending aorta (D) compared among pre-operative, 12-month, 36-month follow-up (FU), and the end of the follow-up

measurements.

J A C C V O L . 6 8 , N O . 1 8 , 2 0 1 6 Li et al.N O V E M B E R 1 , 2 0 1 6 : 1 9 4 4 – 5 4 Endovascular Repair of Ascending Aortic Dissection

1951

pulsating motions of the aortic wall and inadvertentdisplacement of the stent graft. Compared with thedescending aorta, stable fixing of stent graft in thisaortic segment is a challenge. To achieve adequatefixation, a larger oversize rate was needed. However,the risk of stent graft–induced injury increased,which can result in new dissection. The appropriateoversize of stent graft is crucial to balance stablefixation to the aortic wall and less intimal injury.Furthermore, 1 RTAD observed in this series high-lights the fragility of the ascending aorta in dissec-tion and the need for selection of appropriate stentsize and specific device design. To address theseissues, further biomechanical and hemodynamicinvestigation focusing on ascending aorta, stentgraft configuration, and their interaction may beinevitable. And in the future, an endostapling sys-tem should facilitate more favorable fixation, withminimal injury and better long-term performance(25). In addition, this RTAD patient underwent

surgical replacement of dissected ascending aortaand recovered uneventfully, indicating that theendovascular approach can also be used as a bridgein emergent setting for high-risk patients and laterconverted to definitive open repair under improvedpatient conditions.

Manipulation of tracking wire or tapered cone ofthe delivery system in the LV may lead to injury of theintima of the ventricle, which results in adversecardiac events, such as the LV aneurysm seen inour study. This complication was reported to occur inup to 1.9% of patients undergoing transfemoraltranscatheter aortic valve implantation, in whichintraventricular manipulation was also needed(26,27). The J-ended guidewires that are widelyrecommended lower the incidence of LV trauma.Our experience suggests that the grafts with shor-ter and soft tip or nose cone minimize the injurywhen operating the device in the ascending aorta andthe ventricle.

CENTRAL ILLUSTRATION Outcomes of Endovascular Repair for AAD

Li, Z. et al. J Am Coll Cardiol. 2016;68(18):1944–54.

Acceptable mid-term follow-up outcomes of endovascular repair for ascending aortic dissection (AAD) patients at high surgical risk is shown.

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As reported in previous studies on endovascularrepair of descending aortic dissection (28), in mostpatients, the aortic remodeling was completed within1 year after procedure, whereas false lumen throm-bosis rates at the diaphragm level increased over3 years. In our study, significant changes in thediameter of aorta were observed in the first year post-operatively. The diameters of total aorta, true lumen,and false lumen remained stable or changed slightlywithout significant difference at 3 years and duringsubsequent follow-up in the absence of any newdissection or endoleak. It can be explained as acommon process during the aortic remodeling, whichis consistent with long-term results of endovasculartreatment for Stanford type B dissection. In terms ofmorphological changes associated with the ascendingdissection, the therapeutic effect of endovascularexclusion can be sustained.

After graft implantation, the aorta may enlarge andstiffen, and subsequently vascular compliance maydecrease, which could increase systolic pressure,decrease diastolic pressure, and consequently affectcardiovascular health and function resulting in aorticregurgitation and LV hypertrophy (29). We hypothe-size that endografts with greater compliance wouldhave better performance, with mechanical propertiessimilar to those of human ascending aorta, simulatingits contraction and expansion functions. Meanwhile,compliant and flexible devices may interact with theaortic wall with less invasion. Notably, although theCook Zenith TX2 used in this series was not the option

with best compliance (30), our study showed rela-tively low rates of device-related complication andcardiovascular events over time. As no severe aorticregurgitation occurred and the LV ejection fractionremained within normal range despite a slightdecrease, it seems that endografting of the ascendingaorta does not adversely affect long-term cardiacfunction or aortic valve competence. However, thisbenefit should be verified in further studies withlarger sample size and longer follow-up. In the future,studies measuring the circumferential aortic strainand aortic deformation may provide insight into themechanism.

Improvement in stent graft design is needed toachieve better outcomes. Devices with larger diam-eter in shorter length, conformability to the curvatureof aorta and flexibility to decrease device-relatedinjury should be designed. Advanced delivery sys-tems should allow for stepwise deployment andrepositioning for accurate deployment. A short andsoft tip may decrease ventricular and valve trauma. Inthe future, a composite stent graft with a valvecomponent may extend the proximal landing zone tothe aortic valve annulus, and a specially designedbranched stent graft may extend the distal landingzone to aortic arch.

STUDY LIMITATIONS. The sample size of this studywas small (n ¼ 15) and the patients were those whosurvived the initial phase with medicine alone, indi-cating a highly selected cohort with inherent survival

PERSPECTIVES

COMPETENCY IN PATIENT CARE AND PROCEDURAL

SKILLS: In patients with ascending aortic dissection at high

surgical risk, endovascular repair can be performed with minimal

adverse effect on aortic valve function and sustained survival.

TRANSLATIONAL OUTLOOK: Larger studies are needed to

confirm the durability of endovascular therapy compared with

medical treatment and surgical repair and to more clearly iden-

tify those most likely to benefit from this approach.

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bias. Additional studies with patient stratification(e.g., subgroups of acute, subacute, and chronicdissection) based on larger numbers of patients andlonger follow-up are needed to arrive at definitiveconclusions. To verify the long-term effectiveness ofendovascular procedure, comparison with similarpatient cohorts treated with medications is clearlyneeded.

CONCLUSIONS

Currently, open surgery remains the standard therapyfor ascending aorta dissection. The mid-term resultsof our novel endovascular intervention in high-riskpatients suggest acceptable morbidity and mortalitywith positive aortic remodeling and minimal impacton aortic valve function. Longer-term follow-up andlarger studies are required to confirm the effective-ness and durability of this new technique.

ACKNOWLEDGMENT The authors thank SumingZhang, BS, for his contribution to the data collection.

REPRINT REQUESTS AND CORRESPONDENCE: Dr.Zaiping Jing, Department of Vascular Surgery, Chan-ghai Hospital, 168 Changhai Road, Shanghai 200433,China. E-mail: xueguankyj@163.com. OR Dr. JianZhou, Department of Vascular Surgery, ChanghaiHospital, 168 Changhai Road, Shanghai 200433,China. E-mail: zhoujian1-2@163.com.

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KEY WORDS aorta, dissection, grafting,stents