Elephant Trunk after Borst

Editor's Notes

• #3: complications related to the densely adherent tissue surrounding the transverse aortic arch prosthesis and the vicinity of vital vascular and nervous anatomical structures, such as the pulmonary artery, the left recurrent laryngeal or vagus nerves, and the esophagus the aortic arch was replaced first, followed by the remaining affected aorta during a second operation some 4—12 weeks later the one-stage operation due to the long duration of the procedure and hypothermic circulatory arrest, two-stage operation due to the need for a second operation, which sometimes required another period of hypothermic circulatory arrest to perform the proximal anastomosis to the distal aortic arch. Furthermore, the approach to the distal aortic arch, usually via a left thoracotomy, was associated with surgical complication
• #4: Aortic aneurysms represent the 17th leading cause of mortality in United States, with an incidence of 10/100 000 patient-years This is especially true for patients with Marfan syndrome or aortic dissection, who, in time, often require extensive aortic replacement, which presents high complications and mortality rates, due mainly to long or recurrent operative and hypothermic circulatory arrest times However, as each approach has shown technical advantages but also complications at follow-up, the ideal technique for treating complex aortic pathology has yet to be determined.
• #7: As a consequence, in 1983, Borst introduced a significant modification to the two-stage technique. In two patients, affected by aneurysms involving the ascending aorta, arch, and descending aorta, during the first stage, a prosthesis was sutured to the proximal transected descending aorta just downstream from the left subclavian artery. This was left reaching antegradely into the descending aorta over 7—8 cm, giving the appearance of an ‘elephant trunk’. A second prosthesis was then sutured proximally to the first graft and descending aorta and employed to reconstruct the aortic arch. During the second stage, performed some weeks later, the remaining dilated descending aorta was replaced using the ET prosthesis for clamping and suturing another graft to [3]. Soon thereafter, to avoid the risk of tearing the aorta along the fragile distal suture line during the first stage, and to reduce the circulatory arrest time required to suture the additional graft to reconstruct the aortic arch, Svensson modified the original Borst’s technique. He inverted a tubular graft, placed it in the descending aorta, and sutured the double layer head onto the descending aortic wall. The inner segment could then be retrieved and be used for arch reconstruction as usual, leaving an ET in the descending aorta. This modification allowed tightening of the distal suture line, greater surface area between the graft and the aortic wall, and reduction of circulatory arrest times, by making one anastomosis redundant [8]. Several other technical modifications have since appeared, such as performing the distal ET suture between the left subclavian and left common carotid arteries [9] or just in front of the brachiocephalic trunk, leaving, in this last case, a long ET graft segment reaching into the aortic arch and descending aorta and redirecting flow to the supra-aortic vessels through a four-branched prosthesis [10]. Conversely, other authors reported their experience with short or ‘mini’ ET, with the aim to reinforce and protect the distal aortic anastomosis during aortic arch replacement or surgery for aortic dissection [11]. In addition, as the ET can be applied also to other aortic segments, such as the descending or thoraco- abdominal aorta, some authors have employed it in a reversed or bidirectional way, especially in patients needing emergent treatment of those segments, using the invagi- nated limb of the ET prosthesis later to treat the remaining proximal or distal aortic aneurysmal segments [12,13
• #8:   When the descending thoracic aorta is also substantially enlarged, an elephant trunk procedure is used to facilitate the subsequent staged repair of the aorta beyond the left subclavian artery.17 The best exposure is obtained by lowering the head of the operating table. After opening the entire arch, an invaginated graft (A) is placed into the descending thoracic aorta (B), and the graft is attached distal to the left subclavian artery using 3-0 SH or 4-0 RB polypropylene suture (C). As much aortic tissue as possible is incorporated in the anastomosis. Any significant gaps between sutures or other obvious weak spots are reinforced with additional interrupted sutures. The graft is then pulled out in preparation for the brachiocephalic anastomosis. A modification based on this elephant trunk technique can be used to perform total arch repair in patients without descending thoracic aortic aneurysms (as in 3). In this setting, if there is enough space within the aorta, the entire noninvaginated graft can be inserted into the descending thoracic aorta. After the end of the graft is sutured to the aorta just beyond the left subclavian artery, the graft is pulled back out and used to complete the arch repair. (B) After completing the distal anastomosis—either with or without the elephant trunk technique—the graft is placed under tension and an opening is made immediately adjacent to the origins of the brachiocephalic arteries. Because it is unnecessary to divide the aorta completely around the brachiocephalic arteries, we routinely leave the posterior wall intact. The first stitch of a 3-0 SH or 4-0 RB polypropylene suture is placed at the distal posterior portion of the anastomosis. The opening here is very close to the distal anastomosis, and there is usually not enough aortic tissue to allow completely separate anastomoses. Therefore, the distal portion of the brachiocephalic anastomosis often overlaps the superior aspect of the distal anastomosis. This overlapping layer helps prevent an anastomotic leak at this soon-to-be inaccessible area. In order to exclude as much aorta as possible, the sutures are placed very close to the edge of each ostium. After completing the distal and posterior portions of the anastomosis, the other end of the suture is used to complete the anterior and proximal portions of the anastomosis. Several interrupted pledgeted sutures are usually placed to reinforce the anastomosis.
• #10: Regarding the distal anastomosis, we use two techniques. One of them is shown in this figure: that is, a modified elephant trunk technique.5 After ceasing lower systemic perfusion, the folded graft is inserted into the descending aorta. Then, over-and-over sutures are made and the graft is pulled out. To reinforce the anastomosis, we routinely perform double running sutures. As this anastomosis is being completed, perfusion through the femoral arterial line is reestablished to remove air and debris If the descending aorta is too small to put the folded graft in, a straight unfolded graft is inserted into the descending aorta.6 After double running suture technique is performed, the graft is reversed and pulled out. Occasionally, a modified elephant technique for a small descending aorta causes stenosis at the anastomosis.
• #11: The stented end of the ‘hybrid prosthesis’ is deployed in the descending aorta distal of the aneurysmatic segment. Selective antegrade cerebral perfusion is performed during hypothermic circulatory arrest. (b) After suturing the ‘hybrid prosthesis’ circumferentially into the descending aorta directly distal to the origin of the left subclavian artery, the supraaortic branches are reimplanted into the graft as a single tissue patch. (c) The reconstruction may then be completed at any desired level of the ascending aorta while cardiopulmonary bypass is re-established. Benefit FET Distal anast … good hemostatis Lower : Rsidual type IIIb Malperfusion Chronic Ao dilatation Indication FET Promary entry.. Distal arch or unknown True lumen collapse Arch branch involved Arch diameter> 40mm <7o yo
• #12: The ‘hybrid prosthesis’ (‘Chavan-Haverich’ endograft, Curative GmbH, Dresden, Germany – MMCTSLink 142) made of a woven vascular prosthesis with stainless steel stents affixed to the inner aspects at the distal end. The proximal portion of the ‘hybrid prosthesis’ is unstented and consists of a Dacron sleeve ready for conventional surgical handling. A gap of 5 mm between the stents provides flexibility of the graft. The diameter of the stents within the ‘hybrid prosthesis’ ranges from 30 to 46 mm and the stents have a length of 22 mm each. Two longitudinally oriented stainless steel wires maintain the distance between the stents. Depending on individual patient's anatomy, the number of stents may vary between three and four.
• #14: Endovascular stent graft landing zones and hybrid arch repair classification scheme for arch aneurysms. The approach to hybrid arch repair is facilitated when the anatomy of the aortic arch aneurysm is analyzed with regard to 2 main concepts: (1) distal and proximal stent graft landing zone evaluation, and (2) optimization of circulatory management for great vessel revascularization scheme. Both these anatomical concepts are closely related and therefore must be approached in conjunction. Proximal landing zone classification for TEVAR. Typically, thoracic endovascular stent grafts are proximally landed in zones (Z) 2 or 3. Z3 landing is distal to the left subclavian artery (LSCA), but in aneurysms approaching the LSCA, it can be difficult for stent graft landing to achieve a satisfactory seal with no evidence of endoleak. In these patients, Z2 landing zone is required and this occurs between the left common carotid artery (LCCA) and LSCA, thus obligating occlusion of the LSCA. Therefore, typically LCCA-to-LSCA bypass is performed at our institution a few days before the TEVAR procedure. Of note, abandoning the bypass carries a risk for postoperative left upper extremity ischemia and posterior circulatory stroke (ie, dominant vertebral artery). In patients with left internal mammary to coronary artery bypass graft, the LCCA-to-LSCA bypass is a requirement to preserve mammary artery flow. In TEVAR, Z0 and Z1 landing is prohibitive, as it would necessitate occlusion of the head vessels. The hybrid arch concept is an extension of the TEVAR proximal landing zone scheme. Hybrid arch procedures are typically performed with the proximal landing zone in Z0. Therefore, the arch hybrid concept necessitates a brachiocephalic revascularization procedure to preserve flow through the great vessels. (B) The hybrid arch repair classification is based on aortic arch aneurysm anatomy and proximal and distal landing zone feasibility. The scheme divides aortic arch aneurysms into 3 types. Type I arch hybrid is performed typically with a classic arch aneurysm, where the ascending and descending thoracic aorta are not aneurysmal or dissected–isolated arch aneurysm. This anatomy has favorable proximal Z0 and distal Z3/Z4 landing zones, respectively. A type I arch hybrid repair only requires great vessel revascularization with either concomitant antegrade TEVAR stenting or delayed retrograde TEVAR from the iliofemoral vasculature. A type II arch hybrid is an ideal approach in an arch aneurysm without a good Z0 proximal landing zone, but has a good distal landing zone in the descending thoracic aorta. Therefore, a type II repair necessitates an open surgical Z0 landing zone reconstruction for proper deployment and seal of the proximal stent graft. Type III arch hybrid repair can be used for even more complex aortopathies, such as the mega-aorta syndrome. In this case, the native aorta does not have a good proximal or distal landing zone for stent graft deployment. Therefore, a type III repair necessitates an open surgical reconstruction of proximal aorta and arch as a total arch replacement with elephant trunk for stent graft landing in the descending thoracic aorta. It is important to note that in the progression from a type I to type III arch hybrid repair, the circulatory management options become increasingly complex, and therefore, must be tailored to patient status and anatomy.
• #15: Type I arch hybrid repair—isolated arch aneurysm (classic debranching procedure). In the setting of an isolated aortic arch aneurysm, from an endovascular standpoint, proximal Z0 and distal Z3/4 landing zones are already suitable for stent graft deployment. The required open surgical technique is revascularization of the great vessels. (A) The operation is performed as a single-stage procedure. A standard median sternotomy is made and the aorta is exposed in a standard fashion. If the patient has good hemodynamic stability and will tolerate a partial aortic clamp, the great vessel debranching can be performed without cardiopulmonary bypass. If there is sufficient ascending aorta without calcific disease, a side-biting clamp is placed on it and a 4-branched graft is sewn in right above the sinotubular junction. This is to maximize and optimize the proximal Z0 landing zone area. On completion of the anastomosis, the side-biting clamp is removed with individual isolation of each limb of the branch graft. The great vessels are dissected free, and each vessel is then anastomosed individually on proximal ligation. Typically, the LSCA anastomosis is performed first, followed by the LCCA, and then the innominate artery anastomosis is completed last, thus ensuring systemic and cerebral perfusion at all times. (B) If the ascending aorta is inadequate or calcified, or there is concern about the hemodynamic stability of the patient, the type I repair can be performed on cardiopulmonary bypass with a short aortic cross-clamp time. In this situation, the distal ascending aorta and the right atrium are cannulated. The cross-clamp is placed high on the ascending aorta; the heart is arrested, and the 4-limb branch graft is anastomosed to the proximal ascending aorta just superior to the sinotubular junction. The cross-clamp is then removed. The 3 limbs of the branched graft are anastomosed individually to the great vessels; the patient is weaned off bypass, and the aortic cannula is removed. (C) The TEVAR stent graft is then deployed in an antegrade fashion via the 4th limb of the branched graft. The proximal extent of the stent graft is typically just up to the superior portion of the 4-limb branched graft anastomosis. Of note, overextension of the distal landing zone coverage is not necessary, and one should be wary of the risk of spinal cord ischemia with increasing coverage of the descending thoracic aorta. Typically, lumbar drain placement is not required for this procedure, as the aneurysm is strictly an isolated arch aneurysm. At least 2 cm of “good” aorta is required for proper seal proximally and distally, although ideally, the debranching is performed such that there is 3 to 4 cm of proximal landing zone, and at least 2 cm of distal landing zone. (D) During preoperative evaluation of the patient, if there is concern that exposure of the LSCA will be difficult via a median sternotomy incision because of lateral displacement from the arch aneurysm, a preemptive elective carotid to subclavian bypass (LCCA to LSCA) is a good option. This procedure is performed a few days before the type I arch hybrid repair. In this case, the proximal LSCA is covered with the deployed stent graft in the aortic arch. Subsequent coiling of the proximal LSCA via the LCCA-to-LSCA bypass may be necessary to prevent a type II endoleak. Alternatively, the LSCA can just be sacrificed without a carotid subclavian bypass, and the stent graft may provide adequate seal without a type II endoleak. In this situation, the patient should be followed carefully for left arm ischemia, and a carotid-to-subclavian bypass can be then performed as needed.
• #16: The distal aortic arch and proximal descending thoracic aorta are aneurysmal. Establishing a 2-cm proximal landing zone will require covering the origins of the arch vessels with the stent-graft; a debranching procedure will allow for device deployment in the arch while preserving blood flow to these vessels. The distal landing zone exceeds the 2 cm requirement and does not involve the celiac trunk. Despite the availability of a long length of aorta distally, one should not cover more aorta than is necessary to effectively seal the device, because this may cover important intercostal arteries supplying the anterior spinal artery, thereby causing spinal cord ischemia that may result in paraplegia or paraparesis. This illustration demonstrates the surgical approach used for left carotid-to-subclavian artery bypass. A 6- to 7-cm incision is made beginning just lateral to midline, 3 to 4 cm superior and parallel to the clavicle. The platysma muscle is divided, and the clavicular head of the sternocleidomastoid is retracted medially or divided to facilitate exposure. The common carotid artery is dissected free from the adjacent jugular vein and vagus nerve. After the omohyoid muscle and scalene fat pad are divided, the phrenic nerve is identified and protected. The anterior scalene muscle is then divided to expose the subclavian artery. The vertebral and internal thoracic arteries are identified and spared. After heparin is administered, the carotid artery is temporarily clamped while an 8-mm graft is anastomosed to the vessel in an end-to-side manner with 6-0 polypropylene suture. The graft is de-aired and clamped; the carotid clamp is removed, and the conduit is cut to appropriate length. The subclavian artery is then clamped, and an end-to-side anastomosis between the graft and artery is fashioned. The clamps are released, restoring subclavian artery circulation, and, finally, the subclavian artery proximal to the anastomosis is ligated with a heavy silk ligature. Atthispointintheoperation,onehastheoptionofarrangingforanantegradedeploymentoftheendovascular stent-graft or using the more common, retrograde approach. Here, the antegrade approach is illustrated. A 10-mm graft is anastomosed to the proximal ascending aorta on the lateral side; a side-biting clamp is used to exclude a portion of the aorta where the graft is attached. After the anastomosis is completed and the clamp is removed, the side of the 10-mm graft is prepared for insertion of the stent delivery system sheath; using this approach instead of advancing the sheath into the free end of the graft results in better hemostatic control. A clamp is placed on the free end of the 10-mm graft, and a guidewire is introduced into the side of the graft through a needle. Throughout the procedure, fluoroscopic guidance is used to directly visualize each intravascular manipulation of a guidewire, catheter, sheath, and device. The guidewire is advanced through the ascending aorta and arch until it reaches the distal descending thoracic aorta. The introducer needle is removed, and a Bern catheter is used to exchange the flexible guidewire for a stiff one that sits in the descending thoracic aorta. This stiff guidewire is needed to advance the stent-graft delivery system. A needle is used to create a second opening in the 10-mm graft, and a guidewire is advanced for a short distance. Over this guidewire, a 5-French sheath is introduced into the ascending aorta. A marked pigtail catheter is advanced over the guidewire, and the wire is removed. This catheter is used to inject dye for fluoroscopic imaging of the aneurysm and then to determine the length of stent that will be required. (The distance between marks represents 1 centimeter.) Although one should have an idea of the necessary treatment length from the results of appropriate preoperative imaging, it is during this stage of the operation that the final decision is made. An appropriately sized stent-graft can now be advanced over the stiff guidewire in the delivery system sheath until the device lies in position at the distal landing zone; this landing zone must be at least 2 cm in length. The marked pigtail catheter is retracted so as to sit proximal to the proximal portion of the stent-graft, and the device is deployed under direct fluoroscopic imaging while the anesthesiologist suspends ventilation. Should the treatment length require it, additional stent-grafts can be deployed to completely exclude the aneurysm. Obviously, the proximal portion of the stent-graft must not cover the origin of the graft to the great vessels, and the delivery system sheath must also be pulled back far enough so as not to hinder opening of the stent-graft. If a second graft needs to be deployed, it is recommended that there be at least 5 cm of overlap between same-diameter grafts and 3 cm overlap between grafts with different diameters. The general rule is that the larger graft should be deployed within the smaller graft to ensure an appropriate seal. The stent delivery system is then withdrawn through its sheath, and a balloon dilator is advanced through the sheath over the stiff guidewire. An endoluminal balloon is used to expand the proximal landing zone first, then the overlap region(s), if any, and finally the distal landing zone. A final pigtail catheter injection during fluoroscopy is used to confirm proper seating of the stent-graft and complete exclusion of the aneurysm
• #17: The endovascular stent-graft can be introduced retrograde through the femoral artery, external iliac artery, common iliac artery, or distal aorta. This figure shows deployment through the left common femoral artery. The right common femoral artery is used to introduce the marked pigtail catheter for measuring treatment lengths and landing zones. Again, fluoroscopic guidance is used whenever intravascular instruments are manipulated. After the arch vessels have been transferred to the graft off the proximal aorta, a small incision is made over the femoral artery. A soft guidewire is advanced through a needle in the femoral artery until it lies in the ascending aorta. A Bern catheter is used to exchange the soft wire for a stiff one. The sheath for the device is then advanced into the artery over the stiff guidewire. An appropriately sized endovascular stent-graft is then introduced through the sheath until it lies within the proximal portion of the arch. Through the contralateral femoral artery, a marked pigtail catheter is advanced over a guidewire into the ascending aorta. This can be done percutaneously or through a small cut-down. Fluoroscopy with contrast is used to position the device for deployment. The proximal portion is positioned to create a landing zone of at least 2 cm in an area of minimal angulation or tapering. It is important to note that, when deployed, the stent will abut the greater curvature of the aorta, and this must be accounted for during positioning. Otherwise, the proximal portion of the stent-graft may land well short of the intended proximal landing zone as it moves to occupy the curvature of the aorta. A good way to avoid this problem is to make certain that the stiff wire follows the aortic wall along its greater curvature so that the stent-graft, when introduced over this wire, will do likewise. Once the guidewire is properly positioned, the stent is deployed, the landing zones are balloon-dilated, and completion angiograms are obtained. If the aneurysm is of sufficient length to require more than one stent-graft, the general rule is to deploy the smaller graft first. Whenever feasible, the distal-most stent-graft is deployed before proximal grafts are placed. Adequate overlap of grafts is necessary to minimize the risk of endoleak. The deployed and properly seated endovascular stent-graft and debranched aortic arch are pictured in this figure. Here and in the previous figures, the left subclavian artery has been left intact but covered by the stent-graft. In the majority of instances, this can be done without causing postoperative complications. However, this technique has the potential to result in ischemia of the left arm, subclavian steal syndrome, stroke, stent-graft failure due to type II endoleak, and even myocardial ischemia if the patient has a patent left internal thoracic arterial graft supplying a coronary artery. Usually the deployed graft will conform to the greater curvature of the arch and occlude the orifice of the left subclavian artery, thereby preventing back-bleeding and a type II endoleak. If the completion angiogram shows an endoleak in this area despite proper graft deployment and balloon dilation, the left subclavian artery can be ligated and divided (inset) through the sternotomy incision. Covering the left subclavian artery carries a small risk of cerebral ischemia; this risk is increased in patients who are dependent on the left vertebral artery for posterior cerebral perfusion (either because it is the dominant or the sole vertebral artery or because there is concurrent high-grade left common carotid stenosis). The next figures illustrate our approach to maintaining perfusion to the left subclavian artery despite its coverage by the stent-graft
• #18: Type II hybrid arch repair. Type II hybrid arch repair is designed for aortic arch aneurysm that extends proximally into the ascending aorta, and thus an inadequate proximal LZ, or zone 0. Therefore, the open surgical component of the type II repair entails great vessel revascularization with ascending aorta reconstruction. Based on proximal ascending aorta and root anatomy, this may mandate a root replacement ± aortic valve replacement or repair. At our institution, if the ascending aorta is >37 mm, we approach the arch aneurysm as a type II arch hybrid repair. The rationale here is the avoidance of the placement of a large diameter stent graft device in the proximal ascending aorta, which has been shown to be associated with the risk of the development of retrograde type A aortic dissection. Proximal aortic reconstruction will require hypothermic circulatory arrest, with adjunct cerebral perfusion strategies. Options include deep hypothermic circulatory arrest with retrograde cerebral perfusion and moderate hypothermic circulatory arrest with antegrade cerebral perfusion. Both techniques are viable options. (A) Retrograde cerebral perfusion (RCP) approach: The heart is exposed in the pericardial well. The right atrial appendage is cannulated along with a right-angled cannula into the superior vena cava (SVC). A snare is passed around the SVC for later control during RCP. The ascending aorta is cannulated distally and the patient is cooled for deep hypothermic circulatory arrest. During the cooling period, the proximal ascending aortic reconstruction is performed and the great vessels are dissected free. The aorta is cross-clamped distally; the heart is arrested, and the proximal aortic anastomosis is performed just above the sinotubular junction using a 4-limb branched graft with a main body graft for ascending aortic replacement. When fashioning the main body graft for ascending aortic replacement, it is important that the branched graft portion sits right above the sinotubular junction anteriorly. This optimizes the proximal landing zone. If required, any proximal aortic root work necessary can also be performed during this period. Once the patient is cooled to electroencephalogram silence, deep hypothermic circulatory arrest is initiated; the SVC is snared down, and RCP is initiated via the SVC cannula that is connected to the cardioplegia line. Typically the cerebral perfusion is performed with central venous pressure maintained <30 mm Hg. The distal anastomosis is now performed as a transverse hemiarch anastomosis. It is not critical that this be an aggressive hemiarch, as it will be covered by the endograft. (B) On completion of the distal aortic anastomosis, the 4th limb of the branched graft can be used for aortic cannulation and the patient is resumed on cardiopulmonary bypass. RCP is stopped; the SVC snare is removed, and the SVC cannula is used for venous drainage again. Rewarming is begun, and each great vessel is anastomosed individually, with proximal ligation of the vessel. The LSCA is performed first, followed by the LCCA, and then the innominate artery anastomosis. On completion of the great vessel debranching, the patient is weaned off cardiopulmonary bypass once the rewarming is completed. (C) The 4th limb of the branched graft that was used for arterial cannulation for cardiopulmonary bypass is now used for placement of a TEVAR sheath for antegrade deployment. Therefore, this 4th limb should be a 10-mm graft, and it would facilitate placement of the sheath and the stent graft with greater ease. Similar to the type I repair concept, the proximal landing zone of the endoprosthesis is optimized so the proximal seal occurs just above the branched graft site. (D) A pigtail catheter can be guided up into the ascending aorta graft via the 4th limb and an arch angiogram is obtained to ensure there is proper seal proximally and distally. If not, the stent graft can be ballooned again. If the distal landing zone has a type IB endoleak, this may require an additional stent graft to be deployed in an antegrade fashion. Once completed, the 4th limb of the branched graft is ligated. (E and F) Antegrade cerebral perfusion approach. The right axillary artery is exposed first, and then a median sternotomy is performed and the heart and great vessels are exposed. Next, the patient is given 5000 U heparin (70 U/kg) and an 8- or 10-mm straight graft is anastomosed to the axillary artery. The patient is then fully heparinized and the arterial cannulation is completed via the axillary artery graft. The arterial line is prepared with a Y-connector with 2 tubing lines—one to the axillary artery and the other for later cannulation into the branched aortic graft. The right atrium is cannulated for venous drainage. The patient is cooled to 26-28 C, based on surgeon preference, during which time the proximal aortic work is performed. The aorta is cross-clamped; the heart is arrested, and the aorta is transected just above the sinotubular junction. The 4-limb branched graft is used and the proximal aortic anastomosis is completed. The great vessels are dissected free with snares around them for proximal control. On cooling to the desired temperature, the patient is placed on antegrade cerebral perfusion via the axillary artery, with the snare tightened on the innominate artery. Circulatory arrest is initiated and the distal aortic anastomosis is completed as a transverse hemiarch. After completion of the distal transverse hemiarch anastomosis, cardiopulmonary bypass can be reinitiated by increasing the arterial flow in the axillary cannula on loosening the innominate artery snare. The LSCA and LCCA revascularization is performed while on bypass via the axillary artery. Next, to complete the innominate artery anastomosis, the 2nd tubing line of the arterial system is used for cannulation via the 4th limb of the debranching graft to restore systemic perfusion; proximal innominate artery is clamped for the anastomosis, and cerebral flow is maintained via the axillary artery cannula. On completion of the revascularization, if the patient is warm, cardiopulmonary bypass may be terminated and the 4th limb of the graft is used for antegrade stent graft deployment. Alternatively, if the rewarming is not complete, or the heart requires longer perfusion time to improve function, the patient may be switched to the axillary artery cannulation for cardiopulmonary bypass, and while on bypass, the endoprosthesis can be deployed via the 4th limb in an antegrade manner.
• #19: Type III arch hybrid repair. This repair is classically chosen for the treatment of mega-aortic syndrome. In this scenario, the surgeon needs to reconstruct the proximal and distal landing zones for stent graft deployment, along with great vessel revascularization, as the entire ascending aortic arch, and descending thoracic aorta is aneurysmal. This requires a total aortic arch replacement along with an ascending aorta replacement. Given that the total arch replacement likely requires longer circulatory arrest time (>30 min), ACP strategy is our preferred technique for cerebral perfusion. Right axillary artery cannulation is used for arterial cannulation for cardiopulmonary bypass and for antegrade cerebral perfusion during circulatory arrest. If the aneurysmal component displaces the LSCA too laterally, it is preferred that a carotid-to-subclavian artery bypass be performed 2 to 3 days before the total arch repair. Type III arch hybrid is performed in 2 stages, where the ascending aorta + total arch replacement is completed first as an elephant trunk operation, and the patient is brought back 2 to 6 weeks later for deployment of stent graft into the elephant trunk in a retrograde fashion via the femoral artery, as performed in classic TEVAR. (A) Stage I: ascending aorta + total arch replacement (elephant trunk technique). Right axillary artery is cannulated, along with right atrial venous cannulation for initiation of cardiopulmonary bypass. During the cooling period, the ascending aorta is cross-clamped, and the heart is arrested. If necessary proximal work is required, this can be performed during the cooling period. Once the patient is cooled to 26-28 C, circulatory arrest is initiated; the innominate artery is snared down, and antegrade cerebral perfusion is initiated via the axillary artery. An aortic reconstructive graft with 4-limb branches is used and the standard total arch reconstruction using the elephant trunk technique is performed. The distal anastomosis (elephant trunk) is performed in the standard fashion. On completion of the distal anastomosis, distal body perfusion is re-established via CPB and the great vessels are anastomosed individually, from LSCA to innominate artery. The procedure is then completed with proximal anastomosis to the STJ. (B) Stage II: The patient is brought back to the hybrid operating room 2 to 6 weeks after the total arch replacement, and a TEVAR stent is deployed in a retrograde fashion via the femoral artery. Concomitant antegrade TEVAR during the elephant trunk procedure can be technically challenging because of the distal nature of the TEVAR deployment. Placement of a lumbar drain is critical in this situation as the risk of spinal cord ischemia increases with more extensive coverage of the descending thoracic aorta. The proximal landing zone of the stent graft should be just distal to the LSCA anastomosis to optimize the proximal landing zone. Typically, to treat the descending thoracic aortic pathology, multiple stents are required. The distal landing zone of the TEVAR stent needs to have at least 2 cm of nonaneurysmal aorta. (C) Frozen elephant trunk operation (FET). The classic type III arch hybrid is performed as a 2-stage operation, and it carries a small but definite mortality in the interval period between the 2 stages. An alternative approach to consider is the frozen elephant trunk technique, which enables the repair of complex ascending, aortic arch, and descending thoracic aortic disease in a single stage. This technique is appealing in the repair of complex arch + type B chronic dissections with an aneurysmal component. The technique involves using a hybrid prosthesis with a proximal straight Dacron tube graft, and a distal self-expandable nitinol stent graft. The E-vita graft (Jotec, Hechingen, Germany) comes in diameters of 24 to 40 mm, with a standard Dacron tube length of 70 mm and 2 different stent graft lengths of 150 mm or 160 mm. This graft is not available in the USA, but its utility has been described in the literature. At our institution (because of the unavailability of the E-Vita graft), we perform the frozen elephant trunk technique using TEVAR devices available in the USA. The stent graft is deployed into the distal arch/descending thoracic aorta during circulatory arrest, and a 4-branched graft is sewn to the distal arch, with incorporation of the stent graft device in the distal anastomosis. Because this is a single-stage repair, lumbar drain is placed in these patients. Similar to the 2-stage approach, axillary cannulation and right atrial cannulation are performed for cardiopulmonary bypass. The patient is cooled to 26-28 C, during which time proximal aortic work can be performed. This may involve ascending aorta replacement, and, in addition, possibly addressing aortic root/valvular pathology. At 26-28 C, antegrade cerebral perfusion is initiated via the axillary cannula; the innominate artery is snared down, and circulatory arrest is begun. The FET graft is then deployed into the descending thoracic aorta in an antegrade fashion over a stiff guidewire, with the stent graft portion being distal. Care must be taken to ensure that the system is deployed into the true lumen of the aorta if the underlying pathology is a complex aneurysmal dissection. The proximal end of the stent graft portion of the FET graft should be placed 2 to 4 cm from the LSCA takeoff. Next, the proximal Dacron portion of the graft is pulled out into the aortic arch enough that its distal end can be sewn to the distal arch/proximal descending thoracic aorta with a running 3-0 or 4-0 Prolene suture. Next, the proximal portion of the FET graft Dacron portion is tailored for the great vessels to be anastomosed individually or as an island, based on surgeon preference. Once completed, the patient is resumed on cardiopulmonary bypass and the innominate artery snare is taken down. During the rewarming period, the proximal aortic work can be completed if not already done. Finally, the graft-to-graft anastomosis is completed, and the aortic cross-clamp is removed to resume perfusion to the heart. It is recommended that a pigtail catheter be introduced into the descending thoracic aorta via the femoral artery under transesophageal echo guidance to ensure that the distal end of the FET graft is deployed properly with a good seal by obtaining a completion angiogram
• #20: 1) entrapment of the trunk in the smaller dissected aortic lumen downstream without an adequate distal reentry, 2) paraplegia, most likely caused by thrombosis of the Adamkiewicz artery, 3) thromboembolic complications resulting from old clot in the blind aortic pocket surrounding the trunk, 4) splitting of the anastomosis due to enlargement of the false lumen.
• #21: Complex aortic pathology, especially in patients present- ing with an aneurysm involving the aortic arch and proximal descending aorta, has until the 1990s been approached in one or two stages [6,7]. In the latter case, the aortic arch was replaced first, followed by the remaining affected aorta during a second operation some 4—12 weeks later [6]. Both approaches presented technical challenges, the one-stage operation due to the long duration of the procedure and hypothermic circulatory arrest, and the two-stage operation due to the need for a second operation, which sometimes required another period of hypothermic circulatory arrest to perform the proximal anastomosis to the distal aortic arch. Furthermore, the approach to the distal aortic arch, usually via a left thoracotomy, was associated with surgical complications related to the densely adherent tissue surrounding the transverse aortic arch prosthesis and the vicinity of vital vascular and nervous anatomical structures, such as the pulmonary artery, the left recurrent laryngeal or vagus nerves, and the esophagus [2]. ]. Table 1 shows the most up-to-date conventional ET case series reports. Even if the cumulative in-hospital mortality and neurological complications including first and second stages are reported, the results are excellent [8,10,12—25]. As confidence grew and technical adjuncts, such as cerebral protection with retrograde and eventually selective ante- grade cerebral perfusion during arrest [26] and various supra- aortic vessels reconstruction techniques, were introduced, ET indications were further extended. For example, in patients scheduled for descending or thoraco-abdominal aortic surgery, who presented at the same time with a severe coronary artery or valvular disease requiring operation, an ET was placed in the descending aorta to facilitate subsequent aortic repair and similarly, so to speak prophylactically, in selected patients undergoing aortic arch replacement with a downstream aneurysm not requiring immediate surgery at the time, but whose diameter and growth pattern, along with patient risk factors and characteristics (e.g., Marfan syndrome and connective tissue disorders, blood hyperten- sion, and young patients) would suggest an unfavorable development toward further dilation and earlier need for operation [13,14,20—22,25]. Evidence for false-lumen oblit- eration and healing following the use of the ET technique in patients with acute aortic dissection further encouraged its use [10,14—21,24]. Even in aneurysmal disease, some authors have described stabilization or total thromboexclusion using only a long ET. However, in comparison to FET, this protective effect of a simple Dacron vascular trunk is highly dependent on aneurysm extent and diameter and not fully reliable [10]. On the other hand, several complications have been reported, such as kinking or occlusion of the graft in the descending aorta [2], recurrent laryngeal nerve damage [20,22], and SCI, related both to an ET graft longer than 8— 10 cm in the descending aorta and to clotting around the graft with a risk of peripheral thrombo-embolism [2,8,10,13— 15,18,21—23,25]. In patients undergoing operation for chronic aortic dissection, aortic rupture due to ET graft entrapment in the false lumen and malperfusion of visceral arteries supplied by the false lumen due to selective perfusion of the true lumen have been reported [14,22,27]. To avoid these complications, in all patients operated for a chronic aortic dissection, it was then felt imperative to fenestrate the intimal membrane for a length corresponding at least to the ET prosthesis to leave both the true and false lumen perfused [13,14,16,18,20—22]. The presence of a significant interval mortality between the two stages ranging from 3% to 13%, the fact that only 45% of patients, who underwent first-stage ET, returned for second-stage completion, and the complications related to the second stage have convinced some surgeons to perform, whenever possible, a one-stage repair, through a clamshell [28—30], transmediastinal [31] or left posterolateral thor- acotomy approach [32]. As Table 2 shows, lower mortality rates, especially in patients undergoing redo surgery for chronic aortic dissection involving the distal aortic arch and the proximal descending aorta, have thus been reported [28— 34]. However, the long operating times associated with extensive one stage or total replacements of the entire aorta [33,34]; the higher pulmonary complication rates, ranging from 15% to 50%; the need to sacrifice both internal mammary arteries; the postoperative pain; and the inability to extend resection to segments downstream from the diaphragm, have limited their applicability and acceptance considerably. Today, one-stage repair is only performed at a small number of centers. Other surgeons, to shorten the time interval between stages, have propagated hybrid approaches with an endovascular completion of the first-stage ET by implanting covered stent grafts both antegradely [35] or retrogradely [18,21,25,36—39]. This option has been considered particu- larly appealing, as the ET thus functions as a landing zone for such stent grafts. However, the inability to revascularize the intercostal arteries with the risk of spinal cord ischemia, the presence of a long, kinked, or tortuous ET, mobilization of thrombotic material around the prosthesis during catheter manipulation, and the development of endoleaks at follow- up requiring the need of repetitive endovascular procedures have raised some concerns about this approach [37—39].
• #22: most patients, who underwent a conventional two-stage ET procedure, were operated on during the mid- 1980s to 1990s, and relatively few case series of patients affected by acute aortic dissection were reported (Table 1). On the contrary, the FET technique has been developed during the mid-1990s and widely applied only recently, especially in patients presenting with acute or chronic aortic dissection (Table 3). During the time elapsed from the most recent review on this topic [60], 10 new case series with FET have been reported [45—50,52—55], but only three with conventional ET [10,24,25]. As a consequence, newer technical adjuncts, such as antegrade cerebral perfusion, were more commonly and uniformly employed in patients undergoing FET. Furthermore, among FET case series, different stent-graft prostheses have been employed, both homemade and commercially available, making any conclusion even more questionable. During the past 27 years, new techniques have repeatedly been considered to be an ideal solution to treat complex aortic pathology, but enthusiasm partially waned as mid- and long-term follow-up results became available until now, no randomized controlled trial has been performed and, as such, no scientific and statistic-based conclusion could be drawn as to which technique can be considered the most successful in treating complex aortic pathology. Comparisons between techniques by analyzing the retro- spective and prospective case series reported in this article may even be considered futile, due to the different observation periods, patient surgical-risk profiles, surgical indications, and events and morbidity reporting.
• #23: Indeed, some interesting conclusions can be drawn by comparing the case series reported in Tables 1 and 3. FET technique should not strictly be considered a one- stage procedure, as several authors have reported the need for a second operation A consequence, results in Table 3 should be compared more appropriately to the first-stage results of the conventional ET and not to the cumulative ones given in Table 1. At least three reasons justify this statement. First, endoleaks, as previously reported, cannot be completely avoided, Second, complex aortic pathology involves different segments simultaneously but the FET stent graft can cover only a given part of the descending. Third, the initial conception of preventing distal enlargement beyond the stented segment of the descending aorta has not been confirmed and, even if false-lumen thromboexclusion around the stent graft is achieved, this could not prevent distal re-operations during follow-up First, endoleaks, as previously reported, cannot be completely avoided, independent of the generation of graft. Second, complex aortic pathology involves different segments simultaneously but the FET stent graft can cover only a given part of the descending aorta related to its length, requiring subsequent surgical or endovascular procedures to complete aortic repair. Third, the initial conception of preventing distal enlargement beyond the stented segment of the descending aorta has not been confirmed and, even if false-lumen thromboexclusion around the stent graft is achieved, this could not prevent distal re-operations during follow-up, as for example, residual distal patent false lumen favors aortic enlargement [56—59]. Moreover, the extensive use of more aggressive surgical procedures, such as total arch replacement with or without an ET or FET extension to the descending aorta in acute aortic dissection, has been recently questioned by some authors [97,98], who perform a more conservative surgery, by replacing the ascending aorta with or without the hemiarch, as in some patients, especially the older ones, aortic growth rates related to false-lumen patency seem to be slower, probably due to the presence of a stiffer and less elastic aortic adventitia
• #24: However, shortening the stent graft obviously would reduce the number of patients, who could effectively undergo one-stage repair, as aneurysms can involve longer segments of the descending aorta preoperative selection, identifying those patients at higher risk of SCI, employing technical adjuncts, such as perioperative cerebrospinal fluid drainage and perfusion of the left subclavian artery, reducing clamp and hypothermic circulatory arrest times, and limiting the length of the descending aorta covered by the stent graft to the vertebral T7 level.
• #25: At the end of the 1990s and as soon as the first midterm results of TEVAR became available [65,66], different authors began to extend this new technology, first to distal and, subsequently, to more proximal aortic arch pathology [5,67]. By avoiding the use of cardiopulmonary bypass, aortic clamping, and hypothermic circulatory arrest, the aim was to extend aortic arch repair to patients not previously deemed candidates for conventional surgery, due to concomitant co-morbid conditions, such as old age, previous cardiac operations, chronic obstructive pulmonary disease, and previous cerebrovascular accidents. The extension of endovascular treatment to the aortic arch added new challenges to those already experienced with the treatment of the descending aorta. Thus, a proximal landing zone at least 2 cm long at the aortic arch level must take into account the presence of supra-aortic vessels and of anatomic and hemodynamic properties peculiar to the aortic arch, such as its curvature, the high blood-flow velocity usually present in this area, and the substantial movement of this portion of the aorta with each heartbeat in comparison to other aortic segments [68]. To create a suitable landing zone for endovascular repair, authors rerouted blood flow to the supra-aortic vessels prior to stent-graft deployment, by introducing different ‘deb- ranching’ techniques, such as surgical extra-anatomic bypasses or transpositions [69—84] and branched or fene- strated stent grafts [85—93]. Stent-graft completion can then be performed immediately or deferred to arch debranching. According to the Criado and Ishimaru classi- fication of aortic arch landing zones [68], patients requiring stent-graft placement at zone 0 usually undergo pre- emptive total arch rerouting, often through a median sternotomy. Instead, patients requiring stent grafting in zone 1 or 2 undergo double- and single-vessel transposition. This may be achieved by transposing or bypassing the left carotid from the brachiocephalic artery and the left subclavian from the left carotid artery, and by simply bypassing or transposing the subclavian from left common carotid artery, respectively. Although, in the majority of series, the cardiopulmonary bypass is thus avoided alto- gether, there are a few authors, who report brief periods of cardiopulmonary bypass to extend hybrid aortic arch repair to as many high-risk patients as possible, such as those with a compromised cardiac function, who would not tolerate the side clamping of the ascending aorta, those who should undergo concomitant cardiac procedures, and those who present a relatively short ascending aorta and where side clamping of the ascending aorta would involve also the sinotubular junction [75]. Other surgical approaches have been proposed by rerouting blood to the supra-aortic vessels from the femoral arteries or the descending aorta [82], but have been rarely employed. Recently, a new sutureless telescoping anastomosis technique has been introduced, called VORTEC (Viabahn Open Rebranching TEChnique, W.L. Gore & Associates, Flagstaff, AZ, USA), which allows for shorter anastomosing times between the Dacron prosthesis and the supra-aortic vessels, reducing at the same time vessel dissection, manipulation, and ischemia [84]. In contrast to the above surgical debranching, experience with branched and fenestrated stents has been limited by the complex stent-graft deployment and by the risk of stent migration and fracture [85—93]. However, branched stent grafts could potentially allow for total endovascular aortic repair. Inoue treated 14 patients with a single branched stent graft and one patient with a trifurcated stent graft, with primary and secondary success of 60% and 73%, respectively. The need for extensive catheter manipulation with the associated risk of peripheral embolization and the complex stent-graft deployment procedure limited the application of this procedure [89]. Particularly the so-called chimney graft method has the potential to solve a number of the technical problems in endovascular treatment of the arch, but remains to be validated [94]. Furthermore, the presence of aneurysms with a diameter >44 mm, which represents the maximal diameter of avail- able stent grafts, often extending distally to the descending or proximally to the ascending aorta, would preclude endovascular treatment in those patients presenting with complex aortic pathology. Encouraging results have here been obtained by banding the ascending aorta with a Dacron strip during the debranching procedure, which could, in addition, impede further aortic dilation and, if properly marked with clips, guides the surgeon during the subsequent stent deployment. However, extreme banding has been reported to lead to aortic wall necrosis [95]. Other authors have proposed a more aggressive and invasive approach by replacing the ascending aorta with or without the hemiarch using a trifurcated graft and subsequently deploying the stent antegradely through the third branch of the ascending aorta graft or retrogradely through the femoral artery [75,80,83]. Recently, concerns have been raised about the suitability of a woven Dacron graft to serve as a landing zone, as Dacron grafts usually dilate over time to some degree. It has even been proposed that radial forces exerted by the stent may aggravate this process, leading to subsequent type I proximal endoleaks and migration [80]. The lack of a stent graft designed specifically for the aortic arch has been another major concern for surgeons performing endovascular aortic arch repair [68]. All series in Table 4 have employed commercially available stents designed and used for the descending aorta, where anatomy and hemodynamic forces are quite different to the aortic arch. These stents and especially the first-generation ones are rigid and, as a consequence, unable to conform to the aortic arch. This lack of conformity, especially at the proximal stent-graft end, can provoke a progressive collapse of the stent during systole and re-expansion during diastole, leading to fracture or collapse [96]. In addition, the risk of type III endoleaks increases with the number of stents employed, especially in those patients, who present with extensive aortic pathology. Concerns have also been raised about the available delivery systems that can be too short to reach the aortic arch, too rigid to adapt to its curvature and the three-dimensional angulation between the aortic arch and the descending thoracic aorta not allowing precise deployment in this area at high blood flow. Damage to the aortic valve has been another concern [68]. As a consequence, different safeguards have been employed to offset these problems, such as bending the distal end of the introducer, lowering blood flow by using hypotension or rapid pacing, and modifying available or using more flexible stent grafts, such as the Matsui—Kitamura stent (Kitamura Inc., Kanazawa, Japan) [69], which presents a more flexible skeleton than the Z-shape stents. These continuous improvements in surgical procedures and stent design for endovascular aortic arch repair have led to ever-improving postoperative and short-term results with this technique, even in a high-risk surgical population, with in-hospital mortality, stroke, and SCI rates comparable to conventional ET and FET case series, as reported in Table 4. However, long-term results are lacking.
• #26: The favorable early morbidity and mortality rates, reported in Table 4, especially in patients unsuitable for conventional surgery and presenting high American Society of Anesthesiology (ASA) scores, along with a satisfactory technical success [70,73,74], have led some authors to propose this technique as an alternative to open surgery. . For instance, no patient presenting with acute aortic dissection has been treated with this new technique, and this indication alone increases operative risks and postoperative morbidity rates in open surgery case series. Furthermore, authors sustaining the validity and feasibility of this new technique compare its postoperative morbidity and mortality rates to quite old open surgical repair case series results
• #27: . First, as the presence of an endoleak of any type often requires endovascular repair, this new procedure cannot be considered strictly speaking a one-stage technique. In addition, given the notorious tendency of the aorta to dilate and the presence of different concomitant aneurysmal segments, additional endovascular procedures will be required during follow-up. As a consequence, as reported for the FET technique, cumulative complication and success rates must be reported, if a comparison to the two-stage conventional ET technique is made. Second, the need of repetitive endovascular repairs raises a concern about durability and long-lasting benefits for patients compared with open surgical repair Even if feasibility of this technique has been demonstrated, long-term durability and survival results are lacking. Data from TEVAR case series could be extrapolated to endovascular aortic arch repair. In their case series of patients treated between 1992 and 1997 with a homemade, first-generation stent graft, Demers reported an 8 years’ freedom from aortic re-intervention and treatment failure of 70% 􏰀 6% and 39% 􏰀 8%, respectively [100]; but long-term TEVAR durability results could certainly be improved by the introduction of newer stent grafts. By contrast, the long-term survival benefits of stent-graft technology over medical [101] and surgical [102] alternatives are still debated. In the INSTEAD (Investigation of Stent Grafts in Patients With Type B Aortic Dissection) trial, for example, which enrolled patients with uncomplicated chronic Type B dissection, no survival benefit of endovascular over medical therapy was found at 2-year follow-up [101]. Similarly, in a recent meta-analysis of endovascular aortic repair versus open surgical repair for descending thoracic aortic disease, TEVAR failed to show a survival benefit over surgery at follow-up, although all-cause mortality at 30 days was significantly reduced [102]. Recently, the role of stent grafts in treating aortic aneurysms has even been questioned by some authors, who maintain that placement of a stent into the aorta could not impede its natural tendency toward dilation, as the aorta seems to dilate at a mean rate of 0.1 cm year􏰁1 and 0.3 cm year􏰁1 at the ascending and descending aorta levels, respectively, and that this could be particularly aggravated by the stent graft’s radial force, which tends to displace the aortic wall outward, and by the presence of patent intercostals or lumbar arteries, which could keep on perfusing the aneurysmal sac
• #28: As a consequence, endovascular treatment of complex aortic and, especially, aortic arch pathology requires strict imaging follow-up and, until its long-term durability is confirmed, extension of its employment to good surgical candidates may even seem hazardous. In addition, patient psychological stress associated with repetitive controls and procedures must be taken into account, as well as cumulative procedural costs.
• #29: since 1983, different surgical and endovascular techniques have been introduced to treat such a challenging pathology as complex thoracic aortic aneurysms. Every technique showed advantages and drawbacks and, unfortunately, none can be considered the ideal solution for every patient. In addition, the continuous development and introduction of new procedures and the heterogeneity of the pathology treated make randomization near-impossible and comparison difficult. However, an overall conclusion can be drawn from the data gathered here.
• #30: Endoleaks occurs when an aneurymal sac continues to be presurised despite endoluminal stent placement. There are are number of types: type 1 : leak at graft ends (inadequate seal). type 2 : sac filling via branch vessel (eg lumbar or inferior mesenteric artery) most common (80%) sometimes referred to as a "retroleak" enthusiastic examiners sometimes ask for the eponymous name of the large collateral artery between the IMA and SMA = Riolan's arch. most spontaneously resolve and require no treatment. type 3 : leak through a defect in graft fabric (mechanical failure of graft) type 4 : a generally porous graft (intentional design of graft) type 5 : endotension
• #35: Most common types of endoleak: type I (A) from proximal or distal neck; type II (B) from a tributary artery; type III (C) due to stent rupture or malposition; and type IV (D) by graft macroporosity.
• #37: Prf Park ET.. Yg plg ptg… menyiapkan Prox anastomosis Reverse ET.. Menyiapkan distal anastomosis U 2nd stage ptg u identifikasi distal dr ET, krn if tl pendek ga bisa di clamp (buka Ao desc, sementara ET ga di clamp), if panjang cukup… clam ao.. Buka. Identifikasi ET.. Pre op bs pk ETT ato eicard Stage 1 … st 2.. 45%,.. Krn 50% meninggal 25% to sick..25%.. Ga tau kemana, trauma dsb Penting u stage 2 secepatnya… 2-3mg (even same admission) If desending kecil (ex diseksi).. Sulit folding.. Jd masukin tubular (unfold).. Trus anastmsis dg graft… ( if pake 4 brached..jg ga mkn di fold). Lama tp save n bisa u mperkuat diaseksi Klasifikasi debranch.. By bavaria..antegrade stent is only theory krn tant dibikin u retrograde.. Diameter prox n distal ga sama (prox lbh besar) Type 2 yg paling mengutungkan, even ga pake stent krn daerah yg di suture aman n luas..