FROZENIX FACTS

Aortic remodeling withfrozen elephant trunk technique for Stanford type
A aortic dissection using FROZENIX* This article was published in Heart and Vessels on 06 September 2018 (http://doi.org/10.1007/s00380-018-1246-x) [Open access]and Presented at The 70th Annual Scientific Meeting of The Japanese Association for Thoracic Surgery.

Department of Cardiovascular Surgery, Fujita Medical University (former Fujita Health University)

Masato Tochii, M.D., Ph.D.

INTRODUCTION

PATIENTS AND METHODS

Stanford type A aortic dissection (AAD) is associated with

Study patients

extremely poor prognosis and requires immediate surgical

Between January 2005 and March 2017, 187 patients

1, 2). An emergency operation by a simple

underwent surgical treatment for AAD at the Department ofascending aortic replacement may be acceptable, particularly

Cardiovascular Surgery, Fujita Health University, Toyoake,intervention

3)

in elderly patients . Aggressive total arch replacement

Japan. Of these, 51 patients (27.3%) underwent TAR. Since(TAR) is required to avoid a residual dissected aorta with2015, we applied the FET technique with FROZENIX. We

a false lumen patent, particularly in younger patients.

compared 22 and 28 patients who underwent TAR with FET

Although a previous report demonstrated similar outcomesusing the FROZENIX (FET group) and without FET (non-FET

of conservative and aggressive AAD management, the extent

group), respectively. One patient who underwent FET using aof aortic replacement and prolonged surgical procedure time

hand-made open stent graft in 2013 was excluded.

are considered as significant risk factors of early and late inhospital death4–6). The frozen elephant trunk (FET) technique

Device and its selection

is a promising surgical approach to promote false lumen

FROZENIX comprises a distal stented part, made of a polyester

7–12). It is antube, with oval-shaped nitinol stents and a proximal, non-stented

important option in the treatment that allows for single-stage

graft13). It has a unique, interconnected, double-layered, oval-

repair of complex aortic conditions, such as malperfusion, andshaped nitinol stents that conform to the aorta curvature. The

provides a landing zone for possible stent graft procedures10, 13).

surgeon selects the graft diameter in increments of 2 mm (21–39

The FROZENIX (Japan Lifeline Co., Ltd., Tokyo, Japan),mm); the stented part length can be 60, 90, or 120 mm. The total

has been available since 2014 in Japan13). We started the use

length of the FROZENIX is 200 mm.

of FROZENIX for only the AAD patients undergoing TAR

We diagnosed AAD using enhanced computed tomography

at our department since 2015 and not for the atherosclerotic(CT). To decide the FROZENIX size and length, we identified

thoracic aortic aneurysm patients, owing to the associatedthe location of the dissection entry and measured the diameters

obliteration without increasing operative risk

8, 9)

. The FET technique has shown promotionof the descending aorta in the preoperative CT scans, and weof aortic remodeling by maintaining the true lumen flow

recognized the locations of dissection entry in the scans. The

and facilitating its expansion and by promoting false lumen

stented part length was decided by measuring the line of thethrombosis7–10, 12, 14, 15). However, few studies have compared

greater curvature from the origin of the left common carotid

the effectiveness of TAR with and without the FET technique,artery to the descending aorta, without extending to the distalin terms of the downstream aortic remodeling. We comparedsite at the aortic valve level to decrease paraplegia risk. Next, wedownstream aortic remodeling in the AAD patients who

determined the FROZENIX diameter to be approximately 90%

had undergone TAR with/without FET technique usingof the outer aortic diameter or 110% of the true lumen diameter

FROZENIX.

of the descending aorta to use as the distal landing position.

paraplegia risk

1

FROZENIX FACTS

Surgical strategy and TAR with/without FET

common carotid, and brachiocephalic arteries were anastomosed

The surgical strategy and technique are mentioned in ato the respective graft branches.

3)

previous article . The chest was opened through a medianIn the FET group, distal anastomosis was constructed

sternotomy under general anesthesia. In most cases, the rightbetween the left subclavian and left common carotid arteries.

axillary artery and right or left femoral artery were exposed

The origin of the left subclavian artery was dissected tofor arterial cannulation, with which the cardiopulmonary

close the proximal stump. We performed transesophageal

bypass was performed. The patient temperature was cooled

echocardiography proximal to the aortic valve before inducing

down to 25ºC, followed by lower body circulatory arrest withcirculatory arrest using the long-axis view of 3 cm. The

deep hypothermia. Antegrade selective cerebral perfusion

FROZENIX was then inserted and deployed in the true lumen.

was performed by axillary perfusion with a clamped

We adjusted the insertion length based on the non-stented part

brachiocephalic artery and direct cannulation of the leftof the FROZENIX less than 2 cm, and this part was included

common carotid and left subclavian arteries. The operationin the aortic stump. The subsequent procedures were the same

aimed at excluding the dissection entry. When this entry was

as in the non-FET group.

located in the ascending aorta, we performed an ascending aortic
or hemi-arch replacement, or otherwise, we opted for TAR.

Evaluation of distal aortic remodeling after TAR

We aggressively opted for FET technique only when the entry

We performed contrast-enhanced CT prior to hospital

was confirmed in the aortic arch during the operation, owing

discharge to evaluate the false lumen complete thrombosis

to concerns pertaining to inadvertent insertion of the device tip

and true lumen expansion rates by measuring the ratio ofof the FROZENIX through the non-identified entry into thetrue lumen area. When the false lumen was not enhanced

16)

false lumen . Therefore, in the non-FET group, we opted forin the early and delayed phases, it was defined as complete

traditional TAR without FET using step-wise technique.

thrombosis. The finding of so-called partial thrombosis of the

In this group, distal anastomosis was constructed just distal to thedescending aorta, which manifests as enhancement of false

left subclavian artery. The aortic arch was transversely resected,

lumen only in the delayed phase, was defined as incomplete

and dissecting lumen was reinforced with insertion of BioGlue

thrombosis and patent false lumen. The ratio of true lumen

inside the dissecting lumen. The aortic stump was covered witharea was calculated at three levels as follows (Fig. 1);

a paired Teflon felt strip inside and outside the aorta, and thestump was reinforced with continuous 4-0 polypropylene sutures.

Ratio of true lumen area (%)=

A synthetic graft with 4 branches was anastomosed end-to-end

Traced area of the true lumen
Traced area of the whole aorta

X 100

at the distal aortic arch stump, and antegrade systemic perfusion
was initiated. After the proximal anastomosis, the coronary arterywhere the area of whole aorta was traced on the adventitia of

was reperfused by aortic declamping. Then left subclavian, left

the descending aorta.

Fig. 1abcFig. 1-a: The evaluated false lumen complete thrombosis rate and the ratio of true lumen area at three levels of bronchial carina (1), aortic valve(2), and diaphragm (3). Fig. 1-b: The false lumen was not enhanced, and therefore defined as “complete thrombosis.” The ratio of true lumen
was 55.8%, which was calculated by dividing the traced area of true lumen (red line circle, 750 mm2) by the traced area of the whole aorta (dottedline circle, 1350 mm2 ). Fig. 1-c: The false lumen was enhanced, and therefore defined as patent false lumen. The ratio of true lumen was 17.2%(240/1395 mm2 ).

2

FROZENIX FACTS

Data collection and follow-up= 0.7017). The proportion of female patients was comparable

We reviewed the clinical records and data of the study

in the two groups (18.2% vs. 35.7%, for FET and non-FET

patients, including demographics, imaging study results,

group, p = 0.2150). Patients with Marfan syndrome andsurgical treatment details, and surgical outcomes. The in-those with a history of previous cardiac surgery were also

hospital mortality was defined as death caused by any cause

comparable in the two groups. No significant between-groupduring the hospital stay. The follow-up data were obtained,

differences were observed in terms of occurrence of coma or

and the institutional review board approved with a waiver ofloss of consciousness and frequency of organ malperfusion;acquiring informed consent.

preoperative cardiac shock was more frequently recognized in
the FET group (13.6% vs. 0%, for FET and non-FET group, p

Statistical analysis= 0.0786).

Continuous variables are expressed as median and interquartile
range or mean ± standard deviations. Between-group

Surgical procedures (Table 2)

differences in terms of continuous and categorical variables

The rate of concomitant procedures, including aortic root

were assessed with non-parametric (Mann-Whitney) test.

replacement and coronary artery bypass grafting, wasFisher’s χ2 test was used if the expected frequency was <5.

comparable in the two groups. The operation and procedure

P < 0.05 was considered to be statistically significant. Data

times, including cardiopulmonary bypass, cross-clamp,

were analyzed using StatView 5.0 for Windows (SASselective cerebral perfusion, and lower body circulatory arrest

Institute, Inc., Cary, NC, USA).

time tended to be shorter in the FET group; however, thebetween-group difference in this respect was not statistically

Patient demographics and clinical characteristics (Table 1)

significant. The overall average outer diameter of the

In the FET group, all 22 patients underwent TAR withFROZENIX used in this study was 29.0 ± 3.9 mm (range:

FET technique using FROZENIX. After introduction of

23–35 mm). The length of the stented part of the FROZENIXFROZENIX in 2015, 6 patients were included in the non-FET

was 60 mm in 15 patients (68.2%), 90 mm in 6 (27.3%), andgroup treated with traditional TAR.

120 mm in 1 (4.5%), with an average length of 70.9 ± 17.4

The median age in the two groups was 57 (39–84) years andmm.

55 (34–79) years, for FET and non-FET group, respectively (pTable 1 Demographic and clinical characteristics of patients
Age, years
Gender; Male/Female
Marfan syndrome
Shock
Redo/History of cardiac surgery
Coma/Loss of consciousness
Organ malperfusion

FET* (n = 22)
57 (39–84)
18/4
2 (9.1)3 (13.6)
02 (9.1)3 (13.6)

non-FET (n = 28)
55 (34–79)
18/10
3 (10.7)
01 (3.6)0
5 (17.9)

Table 2

P-value
0.70170.21500.64280.0786>.99990.1886>.9999Surgical procedures

Concomitant procedures
Root replacement
Coronary artery bypass grafting
Operation time, min
Cardiopulmonary bypass time, min
Cross-clamp time, min

Data presented as n (%) or as median (interquartile range).
* Frozen elephant trunk

Selective cerebral perfusion, min
Lower body circulatory arrest, min
Stent graft
External diameter of stent graft
23 mm
25 mm
27 mm
29 mm
31 mm
33 mm
35 mm
Mean diameter, mm
Length of stent graft
60 mm
90 mm
120 mmMean length, mm

FET* (n = 22)

non-FET (n = 28)

P-value

4 (18.2%)
1 (4.5)592 ± 171(323–1070)
296 ± 80
(179–517)
183 ± 49
(99–288)
206 ± 57
(76–331)88 ± 24(46–143)

5 (17.9%)2 (7.1)605 ± 144
(434–1005)
294 ± 67
(197–474)
200 ± 61
(121–359)
215 ± 55
(119–340)
94 ± 35(28–226)>.9999>.9999

2
5
2
4
3
3
3
29.0 ± 3.9
15 (68.2%)
6 (27.3%)
1 (4.5%)70.9 ± 17.4

Data presented as n (%) or as mean ± standard deviation (range).
* Frozen elephant trunk

3

0.78320.95000.29760.5742
0.5286

FROZENIX FACTS(39–2515) days for non-FET group. Additional surgery

RESULTS

included a total of 10 surgical procedures in 8 patients [graft

Early and late outcomes (Table 3)

replacement of the descending aortic through left thoracotomy

There was no in-hospital deaths in the FET and 3 deaths in the(n = 5), endovascular stent grafting for the descending aorta

non-FET groups (0% vs. 10.7%, for FET and non-FET group,(n = 3), and thoracoabdominal aortic replacement (n = 2)).

p = 0.2457), respectively. The length of mechanical ventilation

Five of these patients (62.5%) underwent additional surgicalafter surgery was comparable in the two groups (152 ± 223

procedures within one year after the initial emergent TAR,

hours vs. 171 ± 280 hours, for FET and non-FET group,

whereas no additional surgical treatment was performed forrespectively; p = 0.8319). The stay duration of the surviving

residual dissecting aorta in the FET group during the follow-

patients in the intensive care unit (10.5 ± 11.9 days vs. 12.8

up period of 273 ± 236 days (p = 0.0064). (Fig. 2)± 10.4 days, for FET and non-FET group, respectively; p =0.5062) and in the hospital (32.2 ± 20.7 days vs. 49.5 ± 48.2
days, for FET and non-FET group, respectively; p = 0.1053)
and the major morbidity rates, including re-exploration
for bleeding, renal insufficiency requiring hemodialysis,
mediastinitis, respiratory failure requiring a tracheotomy,
or post-surgical stroke, were comparable in the two groups.
Remarkably, none of the patients developed paraplegia.
There was also no late death in both groups, although there
was significant difference in the average follow-up periods[1502 ± 1302 days (range, 69–4088) vs. 273 ± 236 days
(ranged 53–700), for non-FET and FET group, p < 0.0001). At
follow-up, 8 patients in the non-FET group required additional
surgical treatment for residual distal aorta, including stentgrafting and surgical graft replacement. The average durationfrom initial TAR to the additional treatment was 659 ± 858

Table 3 Mortality and morbidity
In-hospital mortality
Extubation, hours
ICU stay among survivors, days
Hospital stay among survivors, days
Morbidity
Re-exploration for bleeding
Renal insufficiency requiring hemodialysis
Mediastinitis
Respiratory failure requiring tracheotomy
StrokeParaplegia
Additional treatment
Late deathFig. 2
FET* (n = 22) non-FET (n = 28)
0
3 (10.7)152 ± 223
171 ± 280
(18–800)(20–1344)
10.5 ± 11.9
12.8±10.4(2–44)(4–49)
32.2 ± 20.7
49.5±48.2(13–94)(12–274)
1 (4.5)2 (9.1)1 (4.5)
3 (13.6)
4 (18.2)0002 (7.1)4 (14.3)
1 (3.6)
3 (10.7)
4 (14.3)
08 (28.5%)
0P-value
0.24570.83190.50620.1053>.99990.6779>.9999>.99990.7155>.99990.0064>.9999

Data presented as n (%) or as mean ± standard deviation (range).
ICU, intensive care unit
* Frozen elephant trunk

The Kaplan-Meier time-related comparison was used for the
freedom from additional surgical treatment after initial TAR in thetwo groups. The p value was not given because of the differenceof follow up duration and short follow up of FET group, although
Log-rank t-test was made.

4

FROZENIX FACTS

False lumen complete thrombosis and ratio of true lumen

The ratio of true lumen area at the level of bronchial carina

area (Table 4)

was significantly higher in the FET group compared with

In comparison, the false lumen complete thrombosis rate atthat in the non-FET group (68.9 ± 18.3% vs. 45.9 ± 23.2%,

the bronchial carina (100% vs. 25%, respectively; for FET and

for FET and non-FET group, respectively; p = 0.0008). The

non-FET group, p< 0.0001) and aortic valve (72.7% vs. 25%,

true lumen area ratio in the FET group was greater at thefor FET and non-FET group, respectively; p = 0.0329) levels

aortic valve (50.7 ± 25.7% vs. 42.0 ± 25.7%, for FET andin the FET group was significantly higher. The false lumen

non-FET group, respectively; p = 0.2355) and diaphragm

thrombosis rate at the diaphragm level showed a higher trend(49.8 ± 26.3%vs. 41.8 ± 28.9%, for FET and non-FET group,in the FET group (50% vs. 25%, for FET and non-FET group,

respectively; p = 0.3522) levels; however, the difference was

p = 0.3580); however, the difference was not statisticallynot statistically significant (Fig. 3 and 4).

significant.
Table 4 False Lumen Complete Thrombosis and Ratio of True Lumen Area
FET* (n = 22)
False lumen complete thrombosis at the level ofBronchial carina
22 (100)
Aortic valve
16 (72.7)
Diaphragm
11 (50.0)
Ratio of true lumen area at the level ofBronchial carina, %68.9 ± 18.3
Aortic valve, %50.7 ± 25.7
Diaphragm, %49.8 ± 26.3

non-FET (n = 28)

P-value

7 (25)
7 (25)
7 (25)<0.0001
0.03290.358045.9 ± 23.2
42.0 ± 25.7
41.8 ± 28.9

0.00080.23550.3522

Data presented as n (%) or as mean ± standard deviation (range).
* Frozen elephant trunk

preoperative

a

b

c

postoperative

d

e

f

3 months after the operation

g

h

i

Fig. 3bronchial carina

aortic valve

diaphragm

CT scan of a patient treated with TAR with FET. Preoperative CT image (Fig. 3 a–c), postoperative image before discharge from the hospital (Fig.
3 d–f), and at 3 months after the operation (Fig. 3 g–i) at the level of bronchial carina (Fig. 2 a, d, g), aortic valve (Fig. 2 b, e, h), and diaphragm (Fig.
3 c, f, i), respectively. Note excellent aortic remodeling of downstream aorta after TAR with FET with the complete thrombosis of false lumen andexpanded true lumen at each level. The false lumen of the descending aorta was complefely disappeared on CT scan taken 3 months after theoperation (Fig. 3 g–i).

5

FROZENIX FACTS

The main fnding of our study is that TAR with FET technique

DISCUSSION

using FROZENIX was associated with more favorable

Life expectancy and the number of patients who undergo

postoperative distal aortic remodeling compared withsurgery for life-threatening acute AAD has increased over timethat without FET in AAD patients. The favorable aortic

in Japan. In 2014, in-hospital mortality after approximately

remodeling resulted from more expanded true lumen, which

5000 operations for acute AAD was reported to be 10.6%

eliminates antegrade false-lumen fow and promotes complete1)in the Japanese Association for Thoracic Surgery registry .

thrombosis of the false lumen in the descending aorta7, 10, 14,

The standard strategy for acute AAD has been ascending

21)

aortic replacement, when the primary intimal tear is in thedissecting aorta was required in the FET group over a follow-

ascending aorta. When the intimal tear is in the distal arch

up period of 273 ± 236 days; however, five patients in theor the descending aorta, TAR is sometimes required as “tear-non-FET group underwent additional surgical proceduresoriented surgery.” However, extensive graft replacement withwithin one year of the initial emergent TAR. Therefore,

TAR is a highly invasive procedure that is associated with an

TAR with FET technique using FROZENIX possibly helps

increased mortality and morbidity risk

3–6)

. Moreover, no additional surgical treatment for residual. In addition, TAR

to reduce vascular complications associated with dilatation

is associated with a high incidence of false lumen patency ofof the residual dissected aorta. In addition, TAR with FET

11, 17, 18). When thetechnique using FROZENIX may save surgical time; in ourfalse lumen is patent after the initial surgery, the additional

study, the procedure-related times, including for operation,

surgical procedure rate, which often requires left thoracotomy

cardiopulmonary bypass, cardiac ischemia, selective cerebral

or re-sternotomy or thoracic endovascular aneurysm repair,

perfusion, and lower body circulatory arrest, tended to beranges from 16% to 26% at 10 years due to descending aortic

relatively shorter in the FET group.

expansion11, 18-22). Some reports demonstrated the feasibility of

To achieve better aortic remodeling, with complete thrombosis

the FET technique for acute AAD to minimize the incidenceof false lumen and true lumen expansion, and to minimize thethe downstream aorta (range, 45.6%–69.7%)

7, 9–12, 15). However, few studies compared TAR

complication with FET technique, adequate size FROZENIX

with/without the FET technique in terms of downstream aortic

should be selected. We decided the size of the FROZENIX

remodeling.

according to the measurement of the true lumen or the wholeof such patency

Fig. 4preoperative

a

b

c

postoperative

d

e

f

bronchial carina

aortic valve

diaphragm

CT scan of a patient treated with TAR without FET before 2015. Preoperative image (Fig. 4 a–c), and postoperative image before discharge fromthe hospital (Fig. 4 d–f) at the level of bronchial carina (Fig. 4 a, d), aortic valve (Fig. 4 b, e), and diaphragm (Fig. 4 c, f), respectively. Note that,
although the elephant trunk was inserted in the descending aorta, the false lumen is patent and the true lumen expansion is not observed ateach level of downstream aorta.

6

FROZENIX FACTS

aorta based on preoperative CT findings. We determineddeveloped stent graft-induced new entry in our study patients. The

the FROZENIX diameter to be about 90% of the outer

very early result of FET is favorable to that of non-FET; however

aortic diameter or 110% of the true lumen diameter of thethe long-term result of FET may be favorable or may not be.

descending aorta, which we would use as the distal landing

There were no significant differences in terms of the false

position. When the true lumen of the descending aorta waslumen thrombosis rate and the ratio of true lumen area atcompressed by the false lumen, we selected the stent graft

the level of diaphragm, although beneficial effects werediameter of 90% of the whole aorta, since a previous reportobserved at the level of aortic valve and bronchial carina. We

demonstrated an 8% increase in the outer diameter due tobelieve that the aortic diameter at the diaphragmatic levelaortic dissection . The stent part of FROZENIX comprised

was affected by two forces: the radial force of blood througha woven structure of Nitinol wire with favorable tractability

the true lumen maintained by the FROZENIX and the false-to the curved aortic arch. However, oversized FROZENIX

lumen pressure from more distal re-entry blood flow. The

may induce intimal damage of descending aorta. Conversely,

existence of re-entries in the mid-descending aorta distal

undersized FROZENIX may also increase the risk of typeto the end of FET, those around the celiac trunk or superior

1b endoleak after FET technique, resulting in incomplete

mesenteric artery might influence the patency of the false

thrombosis of the false lumen and inadequate aortic

lumen in the descending aorta. And whether FET excluded the8)23, 24)

remodelingre-entry in the proximal descending aorta may also influence.

The most fatal complication is spinal cord injury (SCI),

the proximal false lumen patency. Long-term follow-up iswhose mechanism is believed to be multifactorial, including

required to observe the potential adverse effects of abdominal

intraoperative and postoperative blood pressure, distal

re-entry and residual dissection, since residual dissection withposition of the stent graft, atheromatous emboli of the spinala patent false lumen was shown to decrease survival rate andcord artery, duration of circulatory arrest time and pathology

increase aortic events of the downstream aorta19).

of the aorta7, 8, 10, 25). Previous reports demonstrated a higher

The Kaplan-Meier time-related comparison was used

trend of SCI in atherosclerotic aorta rather than in acute aortic

for the freedom from additional surgical treatment after

dissection after the FET technique8, 9). Therefore, we employ

initial TAR in the two groups. The p value was not given

FET technique only for acute aortic dissection.

because of the difference of follow up duration and short

The length of the FROZENIX is also an important point forfollow up of FET group, although Log-rank t-test was

AAD repair; importantly it excludes the dissection entry inmade. However, no patient underwent additional surgicalthe aortic arch or proximal descending aorta8–10). None of thetreatment for downstream aorta in FET group, although 8 ofpatients developed paraplegia. To decrease paraplegia risk, we

28 patients (28.5%) underwent additional surgical treatment

avoid excessive insertion of FROZENIX into the descendingfor downstream aorta in non-FET group during follow up

aorta as it is unnecessary to insert a long FROZENIX toperiod. Of those, 5 of 8 patients (62.5%) underwent additional

achieve aortic remodeling in FET technique that prevents

surgical treatment within one year after initial TAR in non-

SCI. The most important thing is not to insert the too much

FET group, although no patient required those procedures

long FROZENIX in the descending aorta. According to ourin FET group within one year after the initial TAR. It was

results, 60-mm-length FROZENIX was effective to achievesuggested that the FET procedure can reduce the additional

the aortic remodeling with low complication rate; however, insurgical treatment for residual aorta.

some patients, the distal part of the FROZENIX was placed

In conclusion, TAR with FET technique using FROZENIXin the aortic arch. Fortunately, there was no new intimal tearresulted in more favorable postoperative aortic remodelingafter FET in our series; it is better to place the distal part ofpromotes compared with that without FET in AAD patients.

FROZENIX in the descending aorta not in the curved aortic

This favorable aortic remodeling resulted from morearch. As mentioned, the FROZENIX length was decided

expanded true lumen, which eliminates antegrade false-lumen

according to the measurement of the greater curvature fromflow and promotes complete thrombosis of the false lumen

the left subclavian artery orifice to the aortic valve levelin the descending aorta. These favorable effects are expected

to decrease the paraplegia risk. Paraplegia after the FET

to contribute to freedom from long-term complications

technique may be prevented by avoiding deep insertion of

associated with dilatation of the residual dissected aorta.

the stent graft in the descending aorta. Although some reports
reported the possibility of new intimal tear caused by the

Limitations

open stent graft 10, 16, 24) placed in the aortic arch, no patient

The retrospective study design, single-center scope, and

7

FROZENIX FACTS

relatively small sample size are key limitations of the study.
The patient categorization was not random (FET and nonFET
groups) and the treatment strategy was based on the patient’s
condition and surgeon’s preference. Lastly, the follow-up
duration was shorter in the FET group. Although no additional
surgical treatment for downstream aorta was performed in thisgroup, longer observation is required to confrm the benefts ofaortic remodeling associated with this technique.
Funding
There is no outside support for this manuscript, including
funding, equipment, and drugs.
Compliance with ethical standards
Conflicts of interest
All the authors have declared no competing interest.

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