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Total Aortic Arch Replacements With a 4 Branched Frozen Elephant Trunk (FET) Graft in Acute Aortic Dissection (DeBakey type I)

  • Author Footnotes
    $ These authors contributed equally.
    Malakh Shrestha
    Correspondence
    Address reprint requests to: Malakh Shrestha, MBBS, PhD, Department of Cardio-thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625, Hannover, Germany.
    Footnotes
    $ These authors contributed equally.
    Affiliations
    Department of Cardio-Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
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  • Author Footnotes
    $ These authors contributed equally.
    Erik Beckmann
    Footnotes
    $ These authors contributed equally.
    Affiliations
    Department of Cardio-Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
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  • Tim Kaufeld
    Affiliations
    Department of Cardio-Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
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  • Axel Haverich
    Affiliations
    Department of Cardio-Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
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  • Andreas Martens
    Affiliations
    Department of Cardio-Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
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  • Author Footnotes
    $ These authors contributed equally.
      The “frozen elephant trunk” (FET) technique was developed by Karck et al., who modified Borst's ET technique by using a stent graft to secure the distal ET section. Working in collaboration with Vascutek Terumo, we in Hannover Medical School introduced the 4-branched hybrid FET graft In 2012 (Thoraflex Hybrid). However, the results after open aortic arch repair mainly depend on perioperative management and patient factors. Over the years, peri-operative management and operative techniques have evolved greatly contributing to better results. We describe our surgical technique of implantation of this hybrid graft in acute aortic dissection Stanford type A, DeBakey type I (AADA DeBakey I) patients.

      Keywords

      Central Message
      The 4-branched Frozen Elephant Trunk Graft facilitates total aortic arch replacement. Continuous myocardial perfusion helps to decreases the myocardial ischemia time during complex aortic arch surgery, thereby allowing arch replacement in elderly and high-risk patients.

      Introduction

      The original Elephant Trunk technique was first described by Borst et al. in 1983, in order to facilitate the second stage operation after initial total aortic arch replacement in patients with complex pathologies of the thoracic aorta.
      • Borst HG
      • Walterbusch G
      • Schaps D.
      Extensive aortic replacement using "elephant trunk" prosthesis.
      Karck et al. modified Borst's ET technique by using a stent graft instead of Dacron graft for the distal ET section.
      • Karck M
      • Chavan A
      • Hagl C
      • et al.
      The frozen elephant trunk technique: A new treatment for thoracic aortic aneurysms.
      Initially, the FET was used to treat patient having complex thoracic aneurysms with a distal so- called “landing zone” so that these patients could be treated in “single stage”. Over time, indications have expanded and the FET procedure has been used to treat acute aortic type A dissection as well. Nevertheless, performing total aortic arch replacement with FET in acute aortic dissection patients is controversial.
      • Shrestha M
      • Fleissner F
      • Ius F
      • et al.
      Total aortic arch replacement with frozen elephant trunk in acute type A aortic dissections: Are we pushing the limits too far?dagger.
      ,
      • Shrestha M
      • Haverich A
      • Martens A.
      Total aortic arch replacement with the frozen elephant trunk procedure in acute DeBakey type I aortic dissections.
      Nevertheless, it may be helpful in the following conditions: (1) In patients with distal malperfusion, FET has the potential to expand the true lumen in the descending aorta, thus restoring visceral/lower body perfusion.
      • Shrestha M
      • Bachet J
      • Bavaria J
      • et al.
      Current status and recommendations for use of the frozen elephant trunk technique: A position paper by the Vascular Domain of EACTS.
      ,
      • Preventza O
      • Cervera R
      • Cooley DA
      • et al.
      Acute type I aortic dissection: Traditional versus hybrid repair with antegrade stent delivery to the descending thoracic aorta.
      (2) In patients with rupture of the distal aortic arch or the proximal descending aorta, FET may be the only way to save the patient. (3) FET implantation in AADA DeBakey I patients reduces the risk of bleeding from the false lumen in the distal aortic arch and proximal descending aorta. (4) FET implantation in AADA DeBakey I reduces the risk of future surgical interventions of the aortic arch and proximal descending aorta and facilitates (as the classical ET) a second stage procedure, either as a endovascular or open procedure. A FET may be a superior landing zone for secondary endovascular procedures.
      • Rustum S
      • Beckmann E
      • Wilhelmi M
      • et al.
      Is the frozen elephant trunk procedure superior to the conventional elephant trunk procedure for completion of the second stage?.
      (5) A branched hybrid graft allows for selective anastomosis of the supra-aortic vessels, which might result in improved hemostasis.
      Working in collaboration with Vascutek Terumo, we in Hannover Medical School introduced the 4-branched hybrid FET graft In 2012 (Thoraflex Hybrid),
      • Shrestha M
      • Kaufeld T
      • Beckmann E
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: Single-center results of the first 100 patients.
      ,
      • Shrestha M
      • Pichlmaier M
      • Martens A
      • et al.
      Total aortic arch replacement with a novel four-branched frozen elephant trunk graft: First-in-man results.
      which was and still is the only commercially available 4-branched FET graft in Europe and the U.S. At our institution, the Thoraflex Hybrid has become the preferred FET graft to treat complex thoracic aneurysms and aortic dissections. Over the years, our results have proven that total aortic arch replacements with 4 branched FET can be performed with excellent results in patients with AADA DeBakey I.
      • Shrestha M
      • Kaufeld T
      • Beckmann E
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: Single-center results of the first 100 patients.
      ,
      • Shrestha M
      • Fleissner F
      • Ius F
      • et al.
      Total aortic arch replacement with frozen elephant trunk in acute type A aortic dissections: Are we pushing the limits too far?dagger.
      ,
      • Shrestha M
      • Haverich A
      • Martens A.
      Total aortic arch replacement with the frozen elephant trunk procedure in acute DeBakey type I aortic dissections.
      In this manuscript, we present our technique of total aortic arch replacement with the FET technique.

      Main Section (Surgical Technique)

      Direct aortic cannulation using the Seldinger technique under transesophageal echocardiography (TEE) guidance is our standard method for arterial access, even in acute dissection cases (Fig. 1B). If the true lumen cannot be cannulated safely via direct needle placement for the Seldinger technique (e.g. in complete circular aortic dissection), “direct open cannulation” after venous drainage and transection of the aorta at the level of the ascending aorta is our preferred option (Fig. 1C).
      • Conzelmann LO
      • Weigang E
      • Mehlhorn U
      • et al.
      How to do it: Direct true lumen cannulation technique of the ascending aorta in acute aortic dissection type A.
      ,
      • Kitamura T
      • Torii S
      • Kobayashi K
      • et al.
      Samurai cannulation (direct true-lumen cannulation) for acute Stanford Type A aortic dissection.
      For additional cerebral protection, temporary retrograde cerebral flush perfusion (flush RCP) via the superior vena cava is an option to reduce the risk for cerebral embolization during cannulation and surgical dissection of the aortic arch (see also below). Axillary or femoral cannulation is only used in selected patients in our institution (eg, for peripheral ischemia or a circular thrombosed false lumen of the ascending aorta). The left heart is vented through the right superior pulmonary vein. The surgical field is flooded with CO2.
      Figure 1
      Figure 1A, B and C. After a median sternotomy, extra-corporeal circulation (ECC) is initiated with direct cannulation of the aorta and the right atrium (2-stage cannula). Color version of figure is available online.
      In AADA DeBakey I cases the patient is cooled down to a core temperature of 20-22°C. Lower temperatures may be used in malperfusion cases.
      If the aortic valve is pathological, we perform Bentall operation. In case of an intact aortic valve and normal-sized aortic root, we prefer glue-repair with insertion of a Dacron strip to stabilize the aortic wall.
      Both the cardiac perfusion pressure and coronary flow are controlled (target pressure: 60-80 mm Hg, target flow: 150-250 mL/min). Flow can vary significantly depending on cardiac size, pathologies and perfusion temperature. Cardiac perfusion is achieved via the cardioplegia pump. Cardiac perfusion temperature is initially kept as low as the core temperature (20-22°C). After circulatory arrest, both cardiac perfusion and core temperature are gradually increased. Typically, cardiac perfusion pressures are not increased over 80 mm Hg. During cardiac perfusion, the left ventricle is thoroughly vented through the right upper pulmonary vein. After initiating the noncardioplegic, continuous cardiac blood perfusion the aortic arch is then replaced on an empty “beating heart.”
      • Martens A
      • Koigeldiyev N
      • Beckmann E
      • et al.
      Do not leave the heart arrested. Non-cardioplegic continuous myocardial perfusion during complex aortic arch repair improves cardiac outcome.
      In this way, the myocardial ischemia time is reduced, as well as the re-perfusion time and consequently, the total operation time. After rewarming the patient can by directly weaned from ECC. The technique results in a reduced cardiac morbidity and mortality.
      • Martens A
      • Koigeldiyev N
      • Beckmann E
      • et al.
      Do not leave the heart arrested. Non-cardioplegic continuous myocardial perfusion during complex aortic arch repair improves cardiac outcome.
      In order to do this, we selectively cannulate the superior vana cava with a 90° steal cannula. The cannula is connected to the arterial line with a Y-connector to allow for rapid transition between retrograde and antegrade perfusion. The aortic arch procedure starts with clamping of the arterial line to the aortic arch. Thereby lower body HCA is initiated and the aorta is opened. With an open aortic arch the SVC is clamped by placing a straight vascular clamp between the retrograde perfusion cannula and the right atrium. Retrograde cerebral flush perfusion with cold blood (20°C) is initiated. The perfusion pressure is monitored via the central venous line and kept at ≤ 40 mm Hg. Target flow is 500-1000 cc/min and retrograde flow from the supraaortic vessels is confirmed. Cold blood cardioplegia (Buckberg) is our preferred method of myocardial protection, and is given every 30 minutes.
      Retrograde cerebral perfusion helps in retrogradely flushing out possible debris from the aortic dissection itself, aortic cannulation or aortic manipulation. During open surgical preparation of the non-clamped supraaortic vessels flush RCP prevents air embolization. The surgical aortic dissection for implantation of the 4 branched FET prosthesis includes isolation of the supraaortic vessels as buttons and establishment of a distal aortic anastomosis site in zone 2 (proximal to the left subclavian artery [LSA]). After isolation of the innominate artery (IA) and the left common carotid artery (LCCA) catheters (Medtronic, USA; DPL retro-cardioplegia catheters with pressure monitoring line) are placed under direct vision into boththe IA and LCCA. After stopping the flush RCP and declamping the SVC, selective bilateral antegrade cerebral perfusion (SACP) is started at a rate of approximately 10 mL/kg/min. SACP perfusion pressure is kept at ≤65 mmHg at 20°C.
      The left subclavian artery (LSA) is clamped or occluded with a Fogarty catheter (Baxter, USA).
      The aorta is transected between the LCCA and the LSA (zone 2).
      This novel hybrid graft has the following novel features:
      • Consists of unstented Dacron & a stented parts(polyester and nitinol stent)
      • Un-stented part has 4 branches (3 for the supra-aortic arteries and one for the arterial cannulation),
      • The length of the stented part: 10 & 15 cms.
      • The proximal unstented & distal stented parts are available in different sizes
      • a sewing collar for the suturing of distal anastomosis.
      • Radio-opaque markers in the stented part.
      • Fully Sealed Device
      We measure the total diameter of the Descending aorta at the site of “Landing Zone” of the distal end of the stent. We use the FET hybrid graft with 10 cm length.
      After the distal anastomosis is completed, the perfusion to the lower part of the body is restarted via the fourth branch of the graft.
      The venous and arterial cannulae are removed and the fourth branch of the arch graft used for ECC is ligated.

      Short Closing Section

      Performing a total aortic arch replacement with FET in acute aortic dissection patients was and remains controversial.
      • Shrestha M
      • Fleissner F
      • Ius F
      • et al.
      Total aortic arch replacement with frozen elephant trunk in acute type A aortic dissections: Are we pushing the limits too far?dagger.
      ,
      • Shrestha M
      • Haverich A
      • Martens A.
      Total aortic arch replacement with the frozen elephant trunk procedure in acute DeBakey type I aortic dissections.
      Nevertheless, the FET procedure may be helpful in the following situations:
      • 1.
        In patients with distal malperfusion, FET can expand the true lumen in the descending aorta, thereby restoring visceral/lower body perfusion. This hypothesis has also been addressed in the position paper of the EACTS published in 2015.
        • Shrestha M
        • Bachet J
        • Bavaria J
        • et al.
        Current status and recommendations for use of the frozen elephant trunk technique: A position paper by the Vascular Domain of EACTS.
        Although true lumen expansion can sometimes be observed after proximal aortic arch replacement or conventional total aortic arch replacement as well, we believe that the FET's stent graft in the descending aorta has higher capacity to stabilize the true lumen of the dissected aorta.
      • 2.
        In patients with rupture of the distal aortic arch or the proximal descending aorta, FET may be the most expeditious way to save the patient. Bilateral anterior clamshell thoracotomy is technically another approach.
        • Kouchoukos NT
        • Masetti P
        • Mauney MC
        • et al.
        One-stage repair of extensive chronic aortic dissection using the arch-first technique and bilateral anterior thoracotomy.
        Rupture of the aortic arch may be treated with conventional total aortic arch replacement, but rupture of the proximal descending aorta cannot be repaired through a median sternotomy. Repositioning the patient to perform a lateral thoracotomy to reach the descending aorta is not an option in this emergent setting, thus, the FET may be the only way save the patient.
      • 3.
        FET implantation in AADA DeBakey I patients reduces the risk of bleeding from the false lumen in the distal aortic arch and proximal descending aorta. The dissected aorta remains fragile and continous oozing from the distal aorta can often be observed. By reexpanding the true lumen and by stabilizing the dissected walls of the aorta, the FET has the potential to reduce the risk of bleeding.
      • 4.
        FET implantation in AADA DeBakey I patients reduces the risk of future surgical interventions of the aortiac arch and proximal descending aorta and facilitates (as the classical ET) a second stage procedure, either as a endovascular or open procedure. A FET may be a superior landing zone for secondary endovascular procedures.
        • Rustum S
        • Beckmann E
        • Wilhelmi M
        • et al.
        Is the frozen elephant trunk procedure superior to the conventional elephant trunk procedure for completion of the second stage?.
        Although endovascular expansion after classical ET is possible, locating the ET endovascularly is technically more challenging than inserting a wire into a FET. Our group has shown that a FET can facilitate distal second stage repair.
      • 5.
        A branched hybrid graft allows for selective anastomosis of the supra-aortic vessels, which might result in improved hemostasis. Selective anastomosis of the supraaortic vessels allows improved localization of bleeding than the island technique, where bleeding from the distal portion can be surgically hard to stop.
      Over the years, our results have proven that total aortic arch replacements with 4 branched FET can be performed with excellent results in patients with AADA DeBakey I.
      • Shrestha M
      • Kaufeld T
      • Beckmann E
      • et al.
      Total aortic arch replacement with a novel 4-branched frozen elephant trunk prosthesis: Single-center results of the first 100 patients.
      ,
      • Shrestha M
      • Fleissner F
      • Ius F
      • et al.
      Total aortic arch replacement with frozen elephant trunk in acute type A aortic dissections: Are we pushing the limits too far?dagger.
      ,
      • Shrestha M
      • Haverich A
      • Martens A.
      Total aortic arch replacement with the frozen elephant trunk procedure in acute DeBakey type I aortic dissections.
      Patients that gain sustainable benefits from FET implantation in AADA DeBakey I should be carefully selected. Meticulous improvement of the surgical management, such as cannulation strategy, zone 2 anastomosis and organ protection methods (eg, flush RCP and cardiac perfusion) have significantly reduced morbidity and mortality of this complex procedure. This increases availability in more desperate situations such as distal malperfusion syndrome (Figs. 2-11).
      Figure 2
      Figure 2During cooling, the aortic root/ascending aortic procedure and other concomitant cardiac procedures are performed. If the root is dissected and dilated but shows an intact aortic leaflets, we prefer aortic-valve-sparing root replacement (David operation). Color version of figure is available online.
      Figure 3
      Figure 3Thereafter, the left ventricle is de-aired and the heart is perfused antegrade via a cannula (Medtronic Inc, USA; 11 Fr DLP cannula with pressure monitoring tip) inserted proximal to the aortic clamp in the ascending aorta/ascending aortic graft. Color version of figure is available online.
      Figure 4
      Figure 4Immediately after the start of the hypothermic circulatory arrest (HCA) and opening of the aorta, we start a short period of retrograde cerebral flush perfusion (flush RCP) via the superior vena cava (SVC). Color version of figure is available online.
      Figure 5
      Figure 5The aortic arch is inspected in Trendelenburg position. Color version of figure is available online.
      Figure 6
      Figure 6For acute aortic type A / DeBakey I dissections, we use a 4 branched hybrid aortic arch graft. Color version of figure is available online.
      Figure 7
      Figure 7(A) Under Selective Antegrade Cerebral Perfusion (SACP), cardiac perfusion and lower body Hypothermic Circulatory Arrest (HCA) the FET is then deployed in the proximal descending aorta. The distal anastomosis is performed between the origins of the left Common Carotid artery and left subclavian artery (Zone2). (B). (7C): If indicated, we use an endoscope to control the position of the FET after its placement in the descending aorta. Color version of figure is available online.
      Figure 8
      Figure 8Thereafter the aortic arch graft is anastomosed to the ascending aortic graft. Color version of figure is available online.
      Figure 9
      Figure 9(A). The first and the second branch of the aortic arch graft are then anastomosed to the IA and the (B) LCCA, respectively. (B). The LSA is then anastomosed to the third branch of the aortic arch graft and re-warming of the patient is initiated. In cases with difficult exposition of the LSA, it may be anastomosed more distally to a separate graft before initiating HCA and starting surgical arch preparation. The separate graft can be easily connected to the third branch of the prosthesis during lower body reperfusion. Color version of figure is available online.
      Figure 10
      Figure 10After the normal body temperature is reached, the ECC is discontinued. Color version of figure is available online.
      Figure 11
      Figure 11(A). Postoperative CT scan. (B). Schematic diagram after de-cannulation. Color version of figure is available online.

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      Linked Article

      • Commentary: Technology and Technique
        Operative Techniques in Thoracic and Cardiovascular SurgeryVol. 27Issue 3
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          In acute type A aortic dissection (aTAAD), total arch replacement (TAR) with frozen elephant trunk (FET) is controversial outside of the indications of tear involvement or significant aneurysm of the arch. While some single-center studies have suggested that TAR imposes no additional mortality to aTAAD repair,1-2 data from clinical registries,3 meta-analyses4,5, and the Society of Thoracic Surgeons (STS) database6 have shown significantly higher mortality rates with TAR than with hemiarch repair.
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