Frozen elephant trunk usage in acute aortic dissection

Abstract

This review discusses the clinical applications of the frozen elephant trunk procedure for patients with acute aortic dissection. Sub-analysis of the multicenter Japanese Frozenix study, J-ORCHESTRA, are presented, and recent reports of frozen elephant trunk usage for acute aortic dissection are discussed.

Keywords

Aortic aneurysm thoracic aneurysm dissecting blood vessel prosthesis implantation cerebrovascular circulation treatment outcome

Introduction

Clinical outcomes after surgery for acute aortic dissection (AAD) have been improved in recent decades. However, early outcomes in patients who undergo total arch replacement or those with preoperative dissection-related complications or comorbidities remain suboptimal. The frozen elephant trunk (FET) procedure has emerged as a means of facilitating not only distal lumen thrombosis but also easier distal aortic anastomosis during total arch replacement. Several commercially made FET grafts are currently available. In 1996, Kato and colleagues¹ first reported 10 patients who had undergone home-made stent-graft insertion in an aneurysmal descending aorta, and the true lumen in a case of dissected descending aorta. The stent-graft was constructed with a self-expanding stent anchored into the woven Dacron graft. In 2003, Karck and colleagues² reported 4 patients who had custom-made stent-grafts. Since then, the frozen elephant trunk procedure has become widespread, mainly in Europe, and many clinical investigations using commercially made products have been reported.^3–6 In China, Sun’s group developed their own FET which is mainly used in patients with acute type A aortic dissection.⁷

Current status of treatment for acute aortic dissection in databases and registries

According to a survey by the Japanese Association for Thoracic Surgery, which covers 97% of cardiac, thoracic, and esophageal procedures, the annual number of operations for acute type A aortic dissection has steadily increased.⁸ Since 1984, the number of operations for AAD increased to 1022 in 1996, and to 4794 in 2017. The 30-day mortality was 26.7% in 1996, and it improved to 8.9%, and hospital mortality was 11.2% (Figure 1).⁸ The yearly number of the FET prosthesis used in surgical treatment for AAD has dramatically increased since 2015 and exceeded 1000 in 2017 (Figure 2). Abe and colleagues⁹ reported clinical outcomes of patients with surgically treated AAD, using the Japan Cardiovascular Surgical Database. They also reported that the number of surgically treated cases increased from 2436 in 2008–2009 to 3533 in 2014–2015, a 45% increase. Significant changes have been found in patient characteristics over time, including increasing age and rate of preoperative renal failure. Despite worsening risk factors, the unadjusted operative mortality rate for arch replacement showed a significant downward trend. The risk-adjusted mortality rate showed a downward trend both in ascending aorta or hemiarch and arch replacement. On the other hand, the Japanese Registry of All Cardiac and Vascular Diseases database has the data of patients who had medical or surgical treatment for acute type A aortic dissection.¹⁰ Patients who had non-surgical treatment comprised 33% of 10,131 patients from April 2012 to March 2015. The early mortality of patients with medical treatment was reported to be much higher (49.7%) compared to surgical cases (11.8%). The International Registry of Acute Aortic Dissections demonstrated a similar decreasing trend in early adverse outcomes in patients who had surgery for AAD. Their 20-year experience data showed decreased surgical mortality from 25% in 1996 to 18% in 2016.¹¹ On the other hand, in the Society for Thoracic Surgeons data from 2004 to 2016, the early mortality after surgery for AAD has been constant at 18.9%.¹² The German Registry for Acute Aortic Dissection Type A showed early mortality of 16.9% in 2137 patients from 2006 to 2010,¹³ and the Nordic Consortium for Acute Type A Aortic Dissection registry showed early mortality of 18%.¹⁴

Surgery with the frozen elephant trunk procedure in patients with acute aortic dissection

In the technique of total arch replacement,¹⁵ the arterial return is provided by direct cannulation of the ascending aorta or right axillary artery, with return provided by an anastomosed 8-mm Dacron graft (Figure 3a). Cerebral protection is achieved using moderate hypothermic circulatory arrest combined with antegrade cerebral perfusion. The skin incision is extended to the left supraclavicular fossa, and the left subclavian artery is taped medial to the left common carotid artery. Core cooling is performed until both tympanic temperatures go down to 23°C and rectal temperature to 30°C. Total circulatory arrest is obtained with central venous pressure rising to 5 mm Hg. The heart is arrested by infusion of retrograde cardioplegia solution. The aortic cannula is removed, and the aortic arch is opened longitudinally (Figure 3b). A 12F balloon-tipped cannula is inserted into the left subclavian artery (LSCA) and the left common carotid artery (LCCA), and a 15F cannula is placed in the brachiocephalic artery from inside the arch. Antegrade cerebral perfusion is started using a single roller pump with a flow rate of 10 to 12 mL·kg⁻¹·min⁻¹ (Figure 3c). The perfusate temperature is kept at 23°C. The left and right radial pressures, as well as the line pressure of the balloon catheters, are monitored to keep the pressure between 30 and 50 mm Hg. Cerebral oxygen saturation is monitored bilaterally from the forehead using near-infrared spectroscopy. The arch is transected at zone II (between the LCCA and LSCA; Figure 3b). The size of the true lumen of the descending aorta is measured using a ball calliper. The LSCA is transected at its origin, and a 12F cannula is reinserted into the distal lumen. The proximal stump of the LSCA is oversewn using a buttressed 3/0 polypropylene suture (Figure 3h).

The diameter of FET is determined as 90%–100% of the diameter of the descending aorta in cases of acute dissection. The length of the FET is determined by measuring the distance between the anastomosis site and the level of the aortic valve in the descending aorta, or less. A 21 mm × 12 cm Frozenix frozen elephant trunk graft (J-graft; Japan LifeLine, Tokyo, Japan) is prepared. A gentle curve is made at the stent-graft portion of the FET, to conform to the shape of the aortic arch and descending aorta. The descending aorta is filled with blood, and the FET is introduced into the true lumen of the descending aorta. The FET is deployed by pulling the sheath proximally while monitoring with transesophageal echocardiography. A non-stented portion of the FET is resected, and the FET is fixed at the descending aorta with Teflon felt reinforcement using three mattress 4/0 polypropylene sutures (Figure 3d). A 24-mm 4-branched Dacron graft is anastomosed to the stump of the descending aorta, incorporating the FET and Teflon felt, using a long 3/0 monofluorvinylydene suture. Antegrade perfusion of the lower body is slowly started through the 4th side-branch of the graft. Rewarming is then started (Figure 3f). The ascending aorta is transected 1 cm above the sinotubular junction. A 5-mm wide graft strip is placed inside the proximal lumen and fixed with 3 mattress sutures with an outer Teflon strip. A small amount of BioGlue is placed in the proximal false lumen. A continuous horizontal mattress suture is used to close the false lumen (Figure 3e). The four-branch graft is anastomosed to the ascending aorta using monofluorvinylydene suture (Figure 3f). After a de-airing procedure, the graft clamp is released, and the heart is reperfused. After making three buttons of each arch vessel, the LSCA is clamped and reconstructed to a graft branch using a 17-mm needle with 5/0 polypropylene suture (Figure 3g). The button of the LCCA is also anastomosed to a graft branch in the same manner. The balloon cannula is removed near the end of each anastomosis, and liberal backflow is used for flushing out debris. Finally, the brachiocephalic artery is clamped and anastomosed. After defibrillation and de-airing procedures, the patient is weaned off cardiopulmonary bypass (Figure 3h).

J-ORCHESTRA study

The Japan-made FET prosthesis (Frozenix) was first launched in 2014.⁵ The prosthesis consists of a Dacron polyester fabric vascular prosthesis with nitinol stents affixed on the inner aspect. The main advantages of the Frozenix are easier handling and implantability, and better conformation to the curvature of the aortic arch. Since 2014, more than 12,000 prostheses have been implanted. The etiologies of the treated aortic lesions were degenerative aneurysms in 43% of patients, acute type A aortic dissection in 42%, chronic type A dissection in 3%, acute type B dissection in 2%, and chronic type B dissection in 8%.

We conducted a multicenter (41 institutions) prospective study (J-ORCHESTRA; J-Open caRdiac aortic arCH disEase replacement Surgical TheRApy Study) comparing clinical outcomes between patients who had total arch replacement with FET and patients who had total arch replacement with or without the classic free elephant trunk (TAR group).¹⁶ The primary endpoint of this study was patient death. Secondary endpoints were cerebral complications such as stroke and temporary neurological dysfunction, spinal cord complications such as paraplegia, paraparesis, or incontinence, and aortic size in computed tomography scans during follow-up. Forty-one institutions joined in this study that included 372 patients in the FET group and 321 in the TAR group from January 2016 to March 2019. The patients were followed up for three years (Figure 4). Aneurysm lesions in patients in the FET group consisted of a degenerative aneurysm in 55%, acute or subacute (surgery from 2 weeks to 2 months from the onset) aortic dissection in 28%, chronic aortic dissecting aneurysm in 12%, and ruptured aneurysm in 5%. Clinical data of 143 patients with acute aortic dissection who had FET were analyzed. Our other study using the Japanese database from 2013 to 2018 disclosed that 12.2% of 29,486 patients who had surgery for acute aortic dissection had FET procedures.

The results showed that the mean age at operation was 61 years, and male sex was predominant at 69%. Emergency (immediate, 86.7%) or urgent (within 24 h after admission, 4.2%) surgery was performed in 90% of the patients. The majority of patients had moderate hypothermia between 20°C and 30°C, and 80% of patients had antegrade cerebral perfusion. Details of the surgery are listed in Table 1. Hospital death occurred in 3 patients (2.1%) Postoperative new permanent neurological deficit occurred in 11 (7.7%) patients and temporary deficit in 8 patients (5.6%). New paraplegia occurred in 3 patients (2.1%) and paraparesis in 2 patients (1.4%). The other complications are listed in Table 2. The size of the false lumen in the descending aorta after surgery decreased significantly during follow-up (Figure 5).

Table 1.

Details of surgery.

Variable	Value
Median operative time (min) [95%CI]	448 [378–522]
Mean cardiopulmonary bypass time (min)	242.72 ± 72.56
Circulatory arrest, lower body (min)	50.80 ± 22.73
Antegrade cerebral perfusion time (min)	141.50 ± 60.57
Retrograde cerebral perfusion (n)	29/143 (20.3%)
Cardiac ischemic time (min)	135.89 ± 56.11

CI: confidence interval.

Table 2.

Early outcomes.

Outcome	No. of patients
Hospital death	3 (2.1%)
Intensive care unit stay (days)	8.09 ± 11.06
Length of hospital stay (days)	34.65 ± 23.53
Brain complication
Permanent	8 (5.6%)
Temporary	11 (7.7%)
Spinal cord complication
Paraplegia	3 (2.1%)
Paraparesis	2 (1.4%)
Cardiac complication	5 (3.5%)
Pulmonary complication	32 (22.4%)
Renal complication	13 (9.1%)
Bleeding	11 (7.7%)
Infection	2 (1.4%)

Reported studies

Table 3 shows a recent clinical summary of FET experiences in the surgical treatment of AAD.^5–7,^17–23 The aortic lesions associated with AAD included chronic aortic dissection and degenerative aneurysms. Excluding the meta-analysis, early mortality ranging from 1.4% to 17% is acceptable. The incidence of permanent stroke ranged from 2.6 to 14%, and newly developed spinal cord ischemia was noted in 1.2% to 5.1%. The occurrence of postoperative acute kidney injury ranged from 2% to 19%.

Table 3.

Summary of recent reports of frozen elephant trunk usage.

Author	Institute	Year	Study	Study period	n	Prosthesis	Brain protection	CA time (min)	Acute AD (A)	Chronic AD (A)	AD (B)	Non-AD	ED	Stroke	Cord Cx	AKI
Tian	Sydney	2013	Meta-analysis	-2013	1675			48	869	353	85	319	8.3%	4.9%	5.1%	10.9%
Katayama	Hiroshima	2015	OS	1997–2011	224		ACP		103	11	30	80	2.6%	2.6%	3.6%
Shrestha	Hannover	2017	OS	2001–2015	251	Chavan, Evita, Thoraflex	ACP	56	96	52	4	52	11%	14%	2%	2%
Tsagakis	Essen	2018	OS	2005–2017	286				157	66		63	11.0%
Roselli	Cleveland	2018	OS	2009–2016	72				72	0	0	0	4.2%	4.2%	4.2%	2.8%
Poon	ARCH study	2019	Multi-C	2000–2015	471		ACP 294, HCA 210	55	471	0	0	0	11.3%	5.7%	3.9%
Chen	Beijing	2019	Marfan	2003–2015	172	Cronus	ACP		94	78			8.1%	2.9%	1.2%	3.5%
Leone	Bologna	2019	OS	2007–2018	282	Evita, Thoraflex	ACP	49	45	164		72	17%	9%	6%	19%
Okita	J-ORCHESTRA study	2019	Multi-C		372	Frozenix	ACP 80%	51	143	45		223	1.9%	4.8%	2.7%	4.3%
Yoshitake	Saitama	2020	OS	2007–2018	139	Custom made, Frozenix	ACP	67	139	0	0	0	1.4%	3.6%	0.7%	7.2%

ACP: antegrade cerebral perfusion; AD: aortic dissection; AKI: acute kidney injury; CA: circulatory arrest; Cx: complication; ED: early death; HCA: hypothermic circulatory arrest; multi-C: multicenter study; OS: observational study; RCP: retrograde cerebral perfusion.

Discussion

The clinical advantage of FET is thought to be ease of handling the distal anastomosis in total arch replacement. This technique enables anastomosis in zone II, between the LCCA and LSCA, and can reduce the occurrence of left recurrent nerve palsy. In addition, bleeding from the distal anastomosis is seldom seen, and there is a lower incidence of leakage into the distal false lumen, resulting in positive remodelling of the distal aorta.

The Frozenix is structurally simple and very easy to handle. However, some disadvantages do exist. The line-up of the Frozenix consists of a stent length of 6 to 15 cm, with a stent diameter of 21 cm to 39 mm. The main concern in using this method is the relatively higher incidence of development of spinal cord ischemia.¹⁸ A recent survey showed an incidence of spinal cord ischemia of 1.7% in 4600 patients.²⁴ The J-ORCHESTRA study on the Frozenix disclosed a 3.8% incidence of postoperative spinal cord complications. Deliberate deployment of the distal stent-graft in the descending aorta above the level of the aortic valve should be considered to prevent spinal cord complications.¹⁸ There have been some reports regarding the occurrence of stent-graft-induced new entry,²⁵ but we found that its incidence using the Frozenix was quite low because the Frozenix has an internal stent skeleton. The occurrence of stent-graft-induced new entry can be alleviated by inserting the FET in a vertical position. Because the Frozenx has a central lumen to allow a guidewire to lead the stent-graft insertion, liberal usage of a guidewire from the femoral artery is recommended.

Current indications for FET usage are patients with acute type A aortic dissection who require total arch replacement. Degenerative arch aneurysm or chronic aortic dissection with suitable anatomy are relative indications for FET. A shaggy descending aorta or the presence of mega-aorta syndrome are contraindications for FET usage. It was concluded that early outcomes after total arch replacement with/without FET usage are satisfactory. The reported incidence of early death and postoperative neurological complications are acceptably low.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Yutaka Okita

References

Kato

Ohnishi

Kaneko

, et al. New graft-implanting method for thoracic aortic aneurysm or dissection with a stented graft. Circulation 1996; 94(Suppl II): II188–II193.

Karck

Chavan

Hagl

Friedrich

Galanski

Haverich

The frozen elephant trunk technique: a new treatment for thoracic aortic aneurysms.

J Thorac Cardiovasc Surg 2003; 125: 1550–1553.

Jakob

Dohle

Benedik

, et al. Long-term experience with the E-vita Open hybrid graft in complex thoracic aortic disease. Eur J Cardiothorac Surg 2017; 51: 329–338.

Di Bartolomeo

Murana

Di Marco

Pantaleo

Alfonsi

Leone

Pacini

Frozen versus conventional elephant trunk technique: application in clinical practice.

Eur J Cardiothorac Surg 2017; 51(Suppl 1): i20–i28.

Katayama

Uchida

Katayama

, et al. Multiple factors predict the risk of spinal cord injury after the frozen elephant trunk technique for extended thoracic aortic disease. Eur J Cardiothorac Surg 2015; 47: 616–620.

Tian

Wan

Di Eusanio

Black

Yan

TD.

A systematic review and meta-analysis on the safety and efficacy of the frozen elephant trunk technique in aortic arch surgery. Ann Cardiothorac Surg 2013; 2: 581–591.

Zhu

Zheng

, et al. Sun’s procedure for complex aortic arch repair: total arch replacement using a tetrafurcate graft with stented elephant trunk implantation. Ann Cardiothorac Surg 2013; 2: 642–648.

Committee for Scientific Affairs, The Japanese Association for Thoracic Surgery; Shimizu

Okada

Tangoku

, et al. Thoracic and cardiovascular surgeries in Japan during 2017: annual report by the Japanese Association for Thoracic Surgery. Gen Thorac Cardiovasc Surg 2020; 68: 414–449.

Abe

Yamamoto

Miyata

, et al. Patient trends and outcomes of surgery for type A acute aortic dissection in Japan: an analysis of more than 10,000 patients from the Japan Cardiovascular Surgery Database. Eur J Cardiothorac Surg 2020; 57: 660–667.

10.

Yamaguchi

Nakai

Sumita

, et al. Current status of the management and outcomes of acute aortic dissection in Japan: analyses of nationwide Japanese Registry of All Cardiac and Vascular Diseases-Diagnostic Procedure Combination data. Eur Heart J Acute Cardiovascular Care 2019 Aug 28: 2048872619872847.

11.

Evangelista

Isselbacher

Bossone

, et al. Insights from the International Registry of Acute Aortic Dissection: a 20-year experience of collaborative clinical research. Circulation 2018; 137: 1846–1860.

12.

Helder

Schaff

Day

, et al. Regional and temporal trends in the outcomes of repairs for acute type A aortic dissections. Ann Thorac Surg 2020; 109: 26–33.

13.

Conzelmann

Weigang

Mehlhorn

, et al. Mortality in patients with acute aortic dissection type A: analysis of pre- and intraoperative risk factors from the German Registry for Acute Aortic Dissection Type A (GERAADA) Eur J Cardiothorac Surg 2016; 49: e44–5211.

14.

Olssona

Ahlsson

Fuglsang

, et al. Medium-term survival after surgery for acute type A aortic dissection is improving. Eur J Cardiothorac Surg 2017; 52: 852–857.

15.

Okita

The frozen elephant trunk technique for treatment of thoracic aortic aneurysm with Japanese-made open stent graft: FROZENIX. J Visualized Surg 2018; 4: 188. Available at: http://jovs.amegroups.com/article/view/21154/20692

16.

Okita

Frozen elephant trunk with Frozenix prosthesis.

Ann Cardiothorac Surg 2020; 9: 152–163.

17.

Roselli

Rafael

Soltesz

Canale

Lytle

BW.

Simplified frozen elephant trunk repair for acute DeBakey type I dissection.

J Thorac Cardiovasc Surg 2013; 145: S197–S201.

18.

Poon

Tian

Yan

, et al. Frozen elephant trunk does not increase incidence of paraplegia in patients with acute type A aortic dissection. J Thorac Cardiovasc Surg 2020; 159: 1189–96.e1.

19.

Tsagakis

Wendt

Dimitriou

, et al. The frozen elephant trunk treatment is the operation of choice for all kinds of arch disease. J Cardiovasc Surg (Torino) 2018; 59: 540–546.

20.

Shrestha

Martens

Kaufeld

, et al. Single-centre experience with the frozen elephant trunk technique in 251 patients over 15 years. Eur J Cardiothorac Surg 2017; 52: 858–866.

21.

Leone

Beckmann

Martens

, et al. Total aortic arch replacement with frozen elephant trunk technique: Results from two European institutes. J Thorac Cardiovasc Surg 2019.

22.

Chen

Zhi

, et al. Fate of distal aorta after frozen elephant trunk and total arch replacement for type A aortic dissection in Marfan syndrome. J Thorac Cardiovasc Surg 2020; 159: 1201–1211.

23.

Yoshitake

Tochii

Tokunaga

, et al. Early and long-term results of total arch replacement with the frozen elephant trunk technique for acute type A aortic dissection. Eur J Cardiothorac Surg 2020; 1: ezaa099.

24.

Preventza

Liao

Olive

, et al. Neurologic complications after the frozen elephant trunk procedure: a meta-analysis of more than 3000 patients. J Thorac Cardiovasc Surg 2019: S0022-5223(19)32242-1.

25.

Czerny

Eggebrecht

Rousseau

, et al. Distal stent-graft induced new entry after TEVAR or FET - insights into a new disease from EuREC. Ann Thorac Surg 2020; 10: S0003-4975(20)30529-4.