Session Ⅰ-1

Technical Pitfalls and Tricks in Aortic Valve-Sparing Operations

Tirone E. DavidToronto General Hospital, Toronto, ON, Canada

There are basically two types of aortic valve sparing operations: 1. Reimplantation of the aortic valve (David operation) 12. Remodeling of the aortic root (Yacoub operation) 2　Both types of operations provide excellent long-term results as long as they are correctly matched to the pathology and perfectly executed. Aortic root aneurysm associated with genetic syndromes such as Marfan syndrome, Loeys-Dietz syndrome, familial aneurysm, etc. and bicuspid aortic valve syndrome with dilated aortic annulus seem to do better in the long-term with reimplantation of the aortic valve than with remodeling of the aortic root. These patients are usually on their 2nd and 3rd decades of life when they need surgery for aortic root aneurysm or aortic insufficiency with bicuspid aortic valve. Older patients with primarily ascending aortic aneurysm and secondarily dilated aortic sinuses and normal aortic annulus do very well with the remodeling procedure.　Selection of size of the graft is crucial with both types of aortic valve-sparing operations. The original formula described by David and Feindel1 remains very useful when a cylindrical graft is used for the reimplanation procedure. Others surgeons use the height of the commissure between the left and non-coronary cusps to determine the diameter of the graft.3 If neo-aortic sinuses are to be created during the reimplantation proce-dure (something that I no longer do), a graft 2 or 4 mm larger is selected and then reduced back to the original measurement by plicating in the areas corresponding to the nadir of the aortic annulus and in between com-missure after the valve is implanted inside of the graft. Sizing the graft for remodeling is simpler and can be estimated by pulling the 3 commissure upward and approximating them until the 3 cusps coapt centrally. The diameter of the imaginary circle involving all 3 commissures is the diameter of the sinotubular junction and the size of the graft.　Reimplantation of the aortic valve requires dissection of the aortic root at least to level immediately below the nadir of the aorto-ventricular junction.4 Placement of the sutures in the left ventricular outflow tract and Dacron graft ought to be geometrically spaced to correct the dilatation of the aorto-ventricular junction and to recreate its normal crescent shape. Plication in this are must be beneath the sub-commissural triangles of the non-coronary cusp. This suture line corrects the heights of the sub-commissural triangles. Next, the resuspen-sion of the commissures has to be spatially correct to align the cusps within the neo-aortic root. The second suture line should maintain the scallop shape of the aortic annulus and the suturing needle should enter the junction between annulus and sinus to secure this area against the Dacron graft. 　Tailoring of a tubular Dacron graft for the remodeling should take into account that the inter-commissural distances may vary and the width of the neo-aortic sinus should reflect this asymmetry. The height of each neo-aortic sinus should be approximately equal to the diameter of the graft. The graft should be sutured in the inside of the remnants of aortic sinus.　The central portion of the free margins of the cusps should lie within the reconstructed aortic root and well above the level of their nadirs if the size of the graft was correct. However, if the free margin of one or more cusps is elongated, it has to be shortened to bring its central portion to the same level of coaptation as the other cusps. Shortening of the free margin is best done along the nodule of Arantius. If the shortening of the free margin is of 5 or 6 mm in length and the cusp is thin, simple plication is adequate. If larger lengths of shorten-ing are needed or if the cusp is thick, a triangular resection should be performed. This principle is applicable to both reimplantation and remodeling procedures.　I continue to believe that fenestrations along the commissural areas are “stress fenestrations” in patients with dilated sinotubular junction and if left uncorrected can be cause of late failure. Thus, if large fenestrations are present or if the upper rim is very thin, I believe that the free margin of the cusp should be reinforced with a double layer of a fine Gore-Tex suture from commissure to commissure.5　After reimplanting the coronary arteries, valve competence can be assessed by occluding the Dacron graft distally and injecting cardioplegia under pressure. Mild aortic insufficiency causes left ventricular distension; trace does not.　The final assessment of the valve function can only be done by TEE after discontinuation of cardiopulmo-nary bypass. In addition to valve competence the level of coaptation of the cusps within the graft and the coaptation length are important predictors of long-term stability of the repair.6

Session Ⅰ-2

An Individualized Approach to the Ascending Aorta in Bicuspid Aortic Valve

Hans-Hinrich SieversUniversity of Luebeck, Luebeck, Germany

Since everybody is genetically different and living in a different environment the bicuspid aortic valve (BAV) disease (aortic valve and aorta) is heterogeneous. The question is: what is the best treatment for an individual patient with BAV aortopathy to prevent aortic dissection weighing risks and benefits of treatment? No randomized trials (gold standard for evidence care) are available. But we have to decide how to deal with the BAV aortopathy and thus rely on experi-ence. There are several accepted risk factors for dissection including the diameter, family history and progressive growth, thin aortic wall but there are also less well studied aspects based on genes and exposome. The diameter of the ascending aorta increases with age, which includes already some kind of a degenerative process. Diameter and diameter are not the same. For instance a diameter of 40mm in a 30 year old patient has a different meaning compared to a diameter of 40mm in a 60 year old patient. Our results on the association of BAV phenotype on the treatment modalities in 1362 patients needing aortic valve surgery (7977 patient/years with a mean follow up of 5.8 ± 3.6 years range 0-14 years) are presented. Hospital mortality was not different between the groups: no-intervention, aortoplasty and replacement of the ascending aorta, as was the late mortality. There were n=4 re-operations on the ascending aorta in the no-intervention group, n=2 in the aortoplasty group and no in the replacement group. There were more replacements of the ascending aorta in BAV-Type 2 and in BAV-Type 1 LR with insufficiency. Our decision chart is demonstrated, based on diameter, age, body surface area, fragile and thin aortic wall, family history, growth rate, tubular shape (Fazel Type) and BAV-Type. Diameter in relation to body surface area, age and gender (z-value, pathology index) had the largest influence on decision making. The cut-off value is smaller in younger patients (more liberal approach) modulated by the above mentioned parameters. In the future in our center ascending aorta replacement will be performed more liberally in young patients and preferably used compared to aortoplasty. The z-score could get more influence on decision making. In the meantime more potential risk factors of dissection emerged and are discussed. For evaluation of this risk factors, myriad of data are necessary (global data managing) to approach by iterative experience the best treatment for an individual patient (precision medicine).

Session Ⅰ-3

Reoperations on the Aortic Root

Thoralf M. Sundt, IIIMassachusetts General Hospital, Boston, MA, USA

With an increasing number of aortic root operations being performed, one can imagine that reoperation on the aortic root will soon also be on the rise. Whereas in the past the most common indication was either degeneration of a homograft or infection of the mechanical prosthesis, increasingly we can anticipate failure of biological root prostheses. Regardless, these can be challenging operations. The options available depend on the original procedure per-formed. In the setting of an infected or otherwise dysfunctional mechanical valve conduit, a complete redo root is most often required although intentional fracture of a mechanical prosthe-sis within the composite root permitting implantation of a biological prosthesis has been reported for the patient unable to tolerate anticoagulation. A dysfunctional homograft root may, in some instances, be addressed by insertion of a conventional valve within the homograft provided calcification is not extreme. Although reported by a number of authors, I have more often felt uncomfortable that paravalvular leak may develop; a sewing cuff will not must be paid to preserving the coronary buttons. If the wall is quite calcified, one can perform a root endar-terectomy leaving the buttons behind almost intact by working within the root. This is possible because the calcification is limited to the homograft wall and is not invasive. A degenerative stentless xenograft can be managed in a similar manner although the intensity of the inflamma-tion seems to be worse. Of late, transcatheter valve implantation within the homograft root has been suggested and performed a handful of instances with success, however in young patients in his my personal view the proper operation continues to be preferable. Finally, if a stented valve has been implanted within the Dacron graft as a root, the Dacron graft can be opened and the stented valve dismantled leaving behind much of the sewing ring which has been incorpo-rated into the proximal anastomosis. A new stented valve can then be implanted within the Dacron graft itself. This is a remarkably straightforward procedure. For this reason I have come to favor such a valve construct over a homograft or stentless xenograft but the primary operation anticipating that it may be my responsibility to do the reoperation.

Session Ⅰ-4

Acute Aortic Syndrome: Aortic Dissection, Intramural Hematoma, Penetrating Atherosclerotic Ulcer

Yoshikatsu SaikiTohoku University, Sendai, Japan

Acute aortic syndrome (AAS) encompass the acute presentation of patients with one of several life threatening thoracic aortic pathologies including acute aortic dissection (AD), intramural hematoma (IMH), symptomatic penetrating atherosclerotic ulcers (PAU) and traumatic aortic dissection. Advances in diagnostic modalities such as transesophageal echocardiography, con-trast-enhanced CT and MRI have enabled us to differentiate classical AD from other variant forms of acute aortic syndrome. There have been significant controversies regarding the pathogenesis and optimal treatment options for IMH. Accordingly, cardiovascular centers have reported conflicting results on its natural prognosis and treatment outcomes. Recent advances in CT technology yielding higher resolution of aortic images have allowed the detection of an aortic intimal defect in patients with previously deemed as typical IMH. An intimal tear could reportedly be localized during surgery in nearly half of patients with typical CT images conformed to IMH. The prevalence of an intimal tear is significantly lower in patients with IMH than in classical AD patients, yet defi-nitely is increasingly recognized. The mean size of intimal tear is obviously smaller in the IMH than in AD. Hence, IMH in considered to develop largely from an intimal tear and with either no or possibly negligible re-entry, results in a thrombosed false lumen. With these in mind, IMH are referred to as thrombosed dissection. Clinical behavior of hematoma varies from patient to patient. Time-dependent resorption of hematoma is commonly observed. Therefore, alternative treatment strategy can be applied for patients with IMH in contrast with those with AD. For instance, type A IMH can even be conservatively managed at least during acute phase in selected patients. Having documented that, close monitoring with serial follow-up CT scans is mandatory before the patient is allowed to ambulate. PAU typically occurs in patients with extensive atherosclerotic disease most commonly at the descending thoracic aortic area. Subsequent complications of PAU are associated with develop-ment of localized IMH, progression to overt aortic dissection, or rupture. Therefore, PAU is considered to be categorized within a spectrum of variant forms of AD. Although there are conflicting data on behaviors of PAU, established applicability of TEVAR and its reliability in long term durability as a treatment option for the descending thoracic aortic lesions has made the threshold toward the intervention for PAU significantly lower.

Session Ⅰ-5

Management of Malperfusion in Acute Dissection

Yutaka OkitaKobe University, Kobe, Japan

【Objective】 Presenting our experience of surgical strategies for patients who had organ malp-erfusion syndrome associated with acute aortic dissection. 【Patients】 Among 309 patients who underwent aortic repair because of acute type A aortic dissection from October 1999 to June 2015, 97 patients (31.5%) had preoperative organ malperfusion syndrome. Age was 63.6±12.2 years old and 42patients were male. Malperfusion syndrome consisted of brain in 41 patient, coronary arteries in 14, lower limbs in 42, GI tract in 7, and kidneys in 8. Three patients had preoperative ongoing brain ischemia had a temporary external shunt from the femoral artery to the right common carotid artery. Prior to the aortic repair, 3 patients with coronary malper-fusion had coronary intervention or percutaneous cardiopulmonary support. Two patients with superior mesenteric artery obstruction had endovascular intervention or vein bypass to the artery. One patient with lower limb ischemia had external shunt. Other 49 patients underwent aortic repair first. Arterial cannulation in 2 different sites was done in 17 (17.5%) patient. Additional arterial cannulation was performed in the axillary artery in 2 patients, in the ascend-ing aorta in 2, in the femoral artery in 1, and in the left ventricular apex in 1, when arterial perfusion pressure or rSO2 dropped. 【Results】 The 30-day mortality of patients with malperfu-sion syndrome was 13.4% (13 patients) and it was 9.42％ with whole patients. The 30–day mortality of each subset of malperfusion syndrome was 14.6 % in brain, 28.5 % in coronary arteries, 42.8 % in mesenteric arteries, 0 in the kidney and 4.2 % in lower limb group. Three patients who had preceding brain perfusion showed no deterioration of the brain lesions. In contrast, 2 patients who had mesenteric reperfusion first died of GI necrosis and respiratory distress. 【Conclusion】 Worse outcomes of surgery for patients with brain, coronary, or mesen-teric malperfusion secondary to acute aortic dissection was demonstrated. Aggressive reperfusion of the target organs before the aortic repair may be recommended.

Session Ⅰ-6

The Risk of Aortic Dissection in the Moderately Dilated Ascending Aorta: Evaluation of 4654 Individuals

J. Kim 1, M. Spotnitz 2, M. E. Lindsay 3, T. E. MacGillivray 2, E. M. Isselbacher 4, T. M. Sundt 2

1 Dept. of Thoracic and Cardiovascular Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea

2 Division of Cardiac Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA3 Division of Pediatric Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA4 Cardiology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA

Objectives: Recent studies have demonstrated that many patients (~50%) with acute type A aortic dissection (AD) have aortic diameters of less than 55mm at presentation, prompting discussion of lowering the prophylactic surgical guidelines. However, the risk of AD at these smaller diameters is poorly defined. We sought to understand the risk of AD in the moderately dilated ascending aorta using a large echocardiographic dataset.Methods: Using an institutional echocardiography database, we identified 4,654 non-syndromic adults (age, 68.6±13.1 yrs; 1,003 female) with maximal ascending aortic diameter of 40-55mm. In follow-up, timely elective repair of the ascending aorta according to current practice guidelines was prevalent. Primary endpoints were AD or rupture in the ascending aorta, and secondary endpoint was elective repair of the ascending aorta. Stepwise Cox-proportional hazard models were used to determine independent risk factors of endpoints. Median follow-up time was 40.1 months (quartile 1-3, 16.3-60.0 months).Results: Maximal aortic diameters were 40-44mm, 45-49mm and 50-55mm in 4016 (86.3%), 510 (11.0%) and 128 (2.8%) individuals, respectively. 586 individuals (12.6%) had bicuspid aortic valves (BAV). During follow-up, AD and rupture occurred in 13 and 1 patients, respectively, demonstrating linearized incidence of AD/rupture of 0.1% per patient-year. Elective ascending aortic repair was performed for 176 patients (3.8%), 99 cases (2.1%) of which as a concomitant procedure during aortic valve (AV) replacement. On multivariable analyses, independent predictors of AD/rupture were age (HR, 1.06; 95% CI, 1.01-1.12; P=0.024) and baseline aortic diameters (HR 1.20; 95% CI, 1.05-1.36; P=0.006), while baseline aortic diameters (HR, 1.60; 95% CI, 1.27-2.00; P<0.001) and moderate-to-severe AV dysfunction (HR, 8.46; 95% CI, 1.19-60.07; P=0.033) were independent predictors of elective aortic repair. After adjustment, the presence of BAV was not significantly associated with any of primary (HR, 0.94; 95% CI, 0.10-8.40; P=0.95) or secondary (HR, 2.11; 95% CI, 0.35-12.94; P=0.42) endpoints. Risks of AD/rupture within 5 years estimated by logistic regression models were 0.4%, 1.1% and 2.9% at the baseline aortic diameters of 45mm, 50mm and 55mm, respectively. Estimated probability of elective aortic repair within 5 years were 6.4%, 21.2% and 51.4% at the aortic diameters of 45mm, 50mm and 55mm, respectively. (Figure)Conclusions: The risks of AD/rupture were significantly correlated with the aortic diameter in individuals with moderately dilated ascending aorta. The risks, however, were very low when timely elective aortic repair was performed based on current practice guidelines (>55mm). Furthermore, the presence of a BAV had no significant impact on the risk of AD. These findings suggest that prophylactic aortic repair in non-syndromic individuals with moderately dilated ascending aorta may not be needed regardless of the morphology of the AV.

Session Ⅰ-7

Location of Residual Entry after Aortic Repair for Acute Type A Aortic Dissection is Associated with Enlargement of the Downstream Aorta

H. Okamura 1, N. Kimura 1, K. Tanno 2, K. Yuri 1, H. Matsumoto 1, K. Adachi 1, A. Yamaguchi 1, H. Adachi 1

1 Department of Cardiovascular Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan

2 Department of Radiology, Saitama Medical Center, Jichi Medical University, Saitama, Japan

Objective: Risk factors for aortic enlargement after surgery for acute type A dissection have been reported. However, the relationship between residual entry in the downstream aorta and aortic growth is still unclear. The aim of this study is to clarify the influence of location and number of residual entry after aortic repair for acute type A aortic dissection on enlargement of the down-stream aorta.Methods: Between September 2009 and April 2014, 199 patients underwent aortic repair for acute type A dissection at our institution. This study included 75 patients with both a contrast-enhanced computed tomography (CT) obtained at discharge and a subsequent non-contrast CT obtained at least 4 months after the baseline CT. In-hospital mortality cases, DeBakey type II aortic dissection, and patients without CT data were excluded. Mean age was 60.8 ± 12.1 years old. Total arch replacement was performed in 10 patients (13%). Primary entry was resected in 50 patients (67%). Mean period between CTs at discharge and follow-up was 22 ± 16 months (range, 4 to 56 months). The CTs were investigated by a radiologist for the location and number of identifiable entry tears in the downstream aorta as well as the size of the dissected aorta at four different levels: aortic arch, tracheal bifurcation, diaphragm, and celiac artery. Annual aortic growth rates were calculated.Results: Postoperative residual entry was identified in aortic arch in 34 patients (45%), in descending aorta above tracheal bifurcation in 9 patients (12%), in descending aorta below tracheal bifurcation in 21 patients (28%), and in abdominal aorta in 53 patients (71%). Mean aortic growth rates were signifi-cantly higher at three levels of the aorta in patients with residual entry in aortic arch than in those without entry in aortic arch (aortic arch 0.9 ± 4.3 vs. -1.0 ± 6.6 mm/year P = 0.007, tracheal bifurca-tion 1.7 ± 4.8 vs. -0.9 ± 6.4 mm/year P = 0.008, diaphragm 0.8 ± 2.4 vs. -1.0 ± 4.6 mm/year P = 0.027). Residual entry in aortic arch was related to higher patency of false lumen (P = 0.027). Patent false lumen was associated with higher aortic growth rates at tracheal bifurcation and diaphragm (P = 0.029, P = 0.007, respectively). Neither total arch replacement nor resection of primary entry has a significant impact on patency of false lumen. Number of entry tears did not influ-ence aortic growth rates.Conclusions: Patients with residual entry in aortic arch had significantly higher aortic growth rates in the thoracic aorta and higher patency of false lumen. Patients with residual entry in aortic arch need strict sur-veillance during follow-up.

Session Ⅰ-8

15 Years of Surgery for Acute Type A Aortic Dissection in Moderate Systemic Hypothermia

A. Zierer 1, A. El-Sayed Ahmad 1, N. Papadopoulos 1, P. Risteski 1, L. Rings 1, A. Moritz 1, A. Diegeler 2, P. Urbanski 2

1 Johann Wolfgang Goethe University, Frankfurt am Main, Germany2 Cardiovascular Clinic Bad Neustadt, Bad Neustadt, Germany

Objectives: Surgery for acute type A aortic dissection (AAD) remains a surgical challenge because of prolonged operative times, bleeding complications, and a considerable risk of neuro-logic morbidity and mortality. The following study investigates the clinical results after surgical treatment for AAD in selective antegrade cerebral perfusion (ACP) and moderate systemic hypothermia (≥ 28 °C).Methods: Between January 2000 and January 2015, 453 consecutive patients underwent surgi-cal treatment for AAD at 2 referral centers in Germany. Patients mean age was 67 ± 13 years, 298 patients (66%) were men. Selective unilateral or bilateral cerebral perfusion under moderate systemic hypothermia was used in all patients. Ascending aortic replacement, hemiarch replace-ment, and total arch replacement, was performed in 9 patients (2%), 342 patients (75%) and 102 patients (23%), respectively. Clinical data were prospectively entered into our institutional database. Mean late follow up was 7±3 years and was 98 % complete.Results: Cardiopulmonary bypass time accounted for 181 ± 68 minutes and the myocardial ischemic time 107 ± 43 minutes. Mean duration of cerebral perfusion was 46 ± 23 minutes. Mean core temperature amounted to 28,8°C ± 0,6 °C. Unilateral cerebral perfusion was performed in 298 patients (66%), bilateral in 155 patients (34%). Mean intensive care unit stay was 5 ± 7 days. We observed new postoperative permanent neurologic deficits in 27 patients (6%) and transient neurologic deficits in 31 patients (7%). Thirty day mortality was 7 % (n=32). Late survival at 5 years was 77 ± 6%.Conclusions: Our data suggest that antegrade cerebral perfusion in combination with moderate systemic hypothermia (≥ 28°C) can safely be applied to surgery for acute type A dissection and offers sufficient neurologic and visceral organ protection.

Session Ⅱ-1

Deep Hypothermia is the Gold Standard for Cerebral Protection

Thoralf M. Sundt, IIIMassachusetts General Hospital, Boston, MA, USA

Hypothermia is the only demonstrably effective intervention for neuroprotection is clinically employed. In fact its use is expanding in the current era of systemic cooling following out of hospital cardiac arrest. In contrast, other agents such as magnesium and steroids are falling into disuse as no benefit has been shown and in fact some data suggests maybe harmful. The use of cooling to protect the central nervous system including the spinal cord has been explored since the 1950s by Bigelow and DeBakey among others. Accordingly it surely must be considered the Gold standard.From a clinical standpoint, however, the issue is not protection as much as preservation. The objective is preservation of neurologic function throughout the operative episode. In the case either of myocardial or neurologic preservation, the options are maintenance of perfusion or reduction of metabloic demand. Myocardial preservation depends principally upon electrome-chanical arrest as this is the primary driver of metabolic demand. Hypothermia is arguably an adjunct. For the central nervous system, however, even hypothermia to 20° can only reduce the metabolic demand by approximately 75%. The earliest attempts at aortic arch replacement relied upon complex shunting strategies to prevent arresting the circulation to the brain. When Griepp and colleagues introduced the concept that profound hypothermia could sufficiently reduce metabolic demand to permit arresting the circulation to the central nervous system for sufficient period of time to accomplish direct surgical intervention on the arch, it was hailed as a welcome simplification of the opera-tive strategy. It obviated the need for complex shunting and cleaned up the operative field. The trade off was prolonged but not indefinite preservation of neurologic function. Subsequent to this innovation have been improvements in the technical aspects of the operation as well as perioperative care the result of which has been a dramatic reduction in operative mortality. Of late the pendulum has swung back with the readdition of antegrade cerebral perfusion to permit more cokplex procedures at profound hypthermia or to reduce the need for hypothermia. Either way the optimal strategy for any given procedure must depend on the anticipated duration of circulatory arrest and the risks associated with alternative strategies including dislodging atheroembolic material from diseased extracranial vessels. Finally it is worth noting that hypothermia protects not only the central nervous system, but also the viscera. Close attention must be paid to other organs such as the kidneys when using more moderate perfusion strategies are employed.

Session Ⅱ-2

Techniques for Cerebral Protection with Moderate Hypothermia

Kenji MinatoyaNational Cerebral and Cardiovascular Center, Osaka, Japan

Modern aortic arch repair usually involves the use of temporary hypothermic circulatory arrest (HCA). Decrease in the metabolic activity of the brain during hypothermia leads to a reduction in cerebral oxygen demand. Deep hypothermia, therefore, has been the gold standard for aortic arch replacement. However, utilization of antegrade selective cerebral perfusion (ASCP) has recently made it possible to use warmer temperatures. The advantages of warmer tempera-tures are the shorter cardiopulmonary time and reduced risk of severe coagulopathies. The potential disadvantage is a higher risk of neurological complications such as cerebral ischemia or spinal cord ischemia. The location of body temperature measurement is important. Although a variety of sites have been used for temperature monitoring, we should be aware that each site does not always reflect the real cerebral and spinal temperature. The bladder temperature can often be lower than the esophageal temperature when the femoral artery has been used for aortic return. The flow rate of the ASCP is also an important concern. A flow rate of approximately 10 mL · kg−1 · min−1 is required to maintain a perfusion pressure of approximately 60 mmHg, and a higher flow rate can be dangerous with the loss of cerebral blood flow autoregulation during deep hypothermia. However, the flow rate should be increased to 15–20 mL · kg−1 · min−1 to maintain the perfusion pressure at the same level. The use of ASCP appears to have a sound physiologic basis at predetermined target perfusion pressures rather than fixed flow rates during cerebral blood flow autoregulation.Another concern is spinal cord ischemia when circulatory arrest and moderate hypothermia is employed. Despite the research on the circulation in the vertebral spine, there is no current method that completely prevents spinal ischemia. The safe duration of circulatory arrest during moderate hypothermia has not been determined for the prevention of spinal ischemia. However, the high flow rate of SCP may allow sufficient perfusion of the spinal cord and prevent spinal ischemia during circulatory arrest at this temperature. The vertebral artery, which connects to the subclavian artery, is an important source of flow to the anterior cerebral artery. Therefore, perfusion of the subclavian artery should be recommended during moderate hypothermia. The temperature during HCA has been safely increased to 28–30°C in recent reports. This change was derived empirically but safely has been employed in many institutes. The safe margin for appropriate temperatures during HCA has been extended. However, a randomized trial should be conducted to determine the real benefits of moderate hypothermia.

Session Ⅱ-3

Contemporary Technique for Open Aortic Arch Repair

Hitoshi OginoTokyo Medical University, Tokyo, Japan

　Well-established open aortic arch repair is still the gold standard surgical procedure for a variety of aortic arch pathologies including acute or chronic aortic dissection, even in the recent era with total endovascular and hybrid procedures using stent grafts. Its essential surgical techniques consist of adequate establishment of cardiopulmonary bypass (CPB), protection of the brain, spinal cord, and abdominal organs, temperature management, monitoring modalities, and graft anastomosis techniques, particularly of the distal anastomosis to the arch/descending aorta and of the arch-vessel reconstruction. 　Currently, for brain protection, antegrade selective cerebral perfusion (SCP) with deep or moderate hypothermia is the main stream, whereas retrograde cerebral perfusion (RCP) with deep hypothermia is still the alternative. In conjunction with SCP, the arterial perfusion for CPB through the axillary artery is useful, which might be more effective in cases with aortic dissec-tion associated with malperfusion of the innominate artery. On the other hand, in cases requiring limited aortic repair for acute aortic dissection, RCP is simple and safe enough to avoid trouble-some cannulation into the dissecting arch-vessels. 　Another topic on open aortic arch repair is the key distal anastomosis, which has challenging aspects with technical difficulty, time limitation, after-bleeding, and so on. For secure anastomo-sis, various knacks have been attempted, including the step-wise distal anastomosis using another short-length tube graft. In addition, fresh or frozen elephant trunk (open stent tech-nique) procedure is used to secure the anastomosis with inside reinforcement and/or to repair further distal aortic pathologies simultaneously. In acute type A aortic dissection, the latter open stent procedure with entire arch replacement is one of the current major concerns. 　Most of the prostheses are multi-branched gelatin- or collagen-pretreated grafts for individual arch-vessel reconstruction, which has favorably reduced postsurgical bleeding. In addition, vari-ous kinds of surgical glues are effective for less-hemorrhage aortic surgeries in conjunction with meticulous anastomoses. 　With the above refinements, the outcome of open aortic arch repair has improved with lower mortality and neurological morbidity rates less than 5%, particularly, in elective basis. On the other hand, risk factors for mortality are reportedly emergency, advanced age, respiratory failure, coronary disease, and renal failure. Alternatively, less-invasive endovascular or hybrid arch procedures should be indicated for such high-risk patients.　Surgical knacks and pitfalls in the contemporary open aortic arch repair will be discussed.

Session Ⅱ-4

Hybrid Aortic Arch Repair - Present and Future -

Toru KurataniOsaka University Graduate School of Medicine, Osaka, Japan

[OBJECTIVE] Thoracic aortic arch pathologies are extremely burdensome to treat, due to their surgical invasiveness and complexity of anatomy. Unfortunately, conventional surgical treat-ment for aortic arch pathologies is highly invasive, and the results are unfavorable. Less invasive surgical techniques are necessary, and we believe hybrid aortic arch repair serves fascinating outcomes. In this study we elucidate the efficacy of hybrid arch repair including TEVAR with new generation device by use of early and long-term results in our single center.[Methods] We performed 3037 aortic surgeries with stent grafts throughout the past 20 years, and these are 78.2% of all the aortic surgeries. 2122 cases were TEVAR including hybrid opera-tion (aortic arch: 978 cases, thoracic descending: 961 cases, thoraco-abdominal: 183 cases). Regarding 978 arch TEVAR, we have performed open stent graft technique in 384 cases and debranching TEVAR in 594 cases (zone 2 in 226 cases, zone 1 in 247 cases, zone 0 in 121 cases). In terms of zone 0 landing TEVAR, we have performed three challenging total debranching arch repair (simple total debraching TEVAR, banding of ascending aorta and total debranching TEVAR, and graft replacement of ascending aorta and total deb ranching TEVAR). In addition, we have performed TEVAR using the double side branch device by Bolton Medical (Figure) in 17 cases since 2012. Recently we placed filter devices into cervical arteries to protect stroke by debris for shaggy arch aorta cases.[RESULTS] Regarding early results of zone 1 and 2 deb ranching TEVAR, hospital mortally was 3.2%, stroke was 3.2%, and there was no evidence of paraplegia. Survival rate and freedom rate from aortic events were 80.2% and 89.1 % in two years, 71.1% and 87.5% in 5 years, and 71.1% and 79.2% in 10 years. In 121 zone 0 landing cases, survival rate and freedom rate from aortic events were 72.2% and 88.8 % in two and five years. Regarding TEVAR with branch devices, we achieved no hospital death, no stroke, no endoleak, and no other major complication as early results. And there was no death, migration and collapse during the two years follow-up in all cases.[CONCLUSIONS] We achieved the fascinating early and long-term results of zone 1 and 2 debranching TEVAR and zone 0 total deb-ranching TEVAR. In addition, The early and mid-term results of TEVAR with the branch device were excellent. So when the double side branch device will be approved, opera-tive procedure for arch aneurysms will be shifted to TEVAR using the branch device.

Session Ⅱ-5

The Place for the Elephant Trunk

Roberto Di BartolomeoUniversita di Bologna, Bologna, Italy

Surgery for extensive disease of the thoracic aorta remains a great challenge for cardiac sur-geon so different surgical procedures, in single or double stage approach, have been proposed. The Elephant Trunk (ET) technique, first described in 1983 by Hans Borst, involves two open operations. The first-one with median sternotomy and the second performed via left-thoracot-omy. Several usefull modifications of the ET technique have been reported. With the advent of thoracic endovascular aortic repair (TEVAR) for the treatment of the descending aortic aneu-rysms, it is now possible to place a stent graft in a previously placed ET graft. The ET graft is used as a landing zone for TEVAR. This procedure was first described in 1995. With the introduction of the frozen ET technique by Kato in 1996, the role of the classic ET has been downsized as well as the need of subsequent endovascular completion. Actually, the exact role of the classic ET technique in the surgery of the complex lesions of the thoracic aorta remains debated and controversial.We discuss about what is today the main indications and the correct use of this technique.

Session Ⅱ-6

The Directional Dependency of Ascending Aorta Biomechanics Disappears with Severe Medial Degeneration

J. Chung 1, K. Lachapelle 1, R. Cartier 2, R. Mongrain 3, R. Leask 31 Cardiac Surgery, McGill University, Montreal, QC, Canada2 Cardiac Surgery, Montreal Heart Institute, Montreal, QC, Canada3 Mechanical Engineering, McGill University, Montreal, QC, Canada

Objective: The study of biomechanics can potentially provide insight into the pathogenesis of aortic complications and improve risk assessment. Aortas are described to have anisotropy, the directional dependency of mechanical properties. We hypothesize that disease-related remodelling of the aortic wall microstructure found in ascending aortic aneurysms results in changes in anisotropy.Methods: Excised aneurysmal ascending aortic tissue was obtained at the time of surgery and control tissue was obtained at organ donation or autopsy. The tissue was subjected to biaxial tensile testing. Stress-strain relationships were collected in both the circumferential and axial directions; from this data, both the apparent modulus of elasticity and energy loss were derived. Energy loss describes normalized hysteresis between aortic loading and unloading curves. Movat pentachrome histological staining was performed on each sample and aortic wall composition was quantified colorimetrically.Results: Energy loss was greater in the circumferential direction than in the axial direction for both aneurysmal and control aortas (p<0.0001), while the modulus of elasticity was the same in both directions. This directional dependency in energy loss became diminished in larger aortas (r2=0.15, p=0.01), especially when indexed to body surface area (r2=0.29, p=0.002), aortas with greater energy loss (r2=0.44, p<0.0001), and aortas associated with tricuspid valves (p=0.004). An inflection point was noted in disease severity separating two populations: aortas without any directional dependency in energy loss (isotropic), and those with varying degrees of anisotropy. Aortas with indexed aortic size greater than 3.5 cm/m2 or energy loss greater than 35% were uniformly isotropic. Evaluating the microstructure, aortas with elevated collagen- to-elastin ratios (greater than 2) reflecting severe medial degeneration, were also uni-formly isotropic. Aneurysmal aortas with higher collagen-to-elastin ratios tended towards isotropy (r2=0.29, p=0.001).Conclusions: Energy loss detects the aniso-tropic nature of aortic tissue unlike the apparent modulus of elasticity; this is further evidence that it may be a more sensitive and physiologically relevant metric in the evaluation of aneurysmal disease. Isotropy is associated with severe medial degeneration indicating that destruction of microstructure can be captured by global biomechanics, thereby identifying energy loss isotropy as a marker of disease severity.

Session Ⅱ-7

Clinical Impact of Chronic Kidney Disease for Open Aortic Arch Surgery with Hypothermia

H. Furukawa, T. Tamura, T. Honda, H. Takiuchi, T. Yamasawa, M. Kuinose, K. Tanemoto

Department of Cardiovascular Surgery, Kawasaki Medical School, Kurashiki, Japan

Objective: Chronic kidney disease (CKD) is common among patients with thoracic aortic aneu-rysms (TAAs) and sometimes affects clinical outcomes. In this retrospective analysis, we evaluated the initial clinical impact of CKD on TAA surgery with hypothermia.Methods: One hundred and seventy-seven consecutive patients who underwent aortic arch surgery by graft replacement (GR) for true, dissecting, and mycotic TAAs in our institute between 2000 and 2014 participated in this study. Thoracic endovascular aortic repair (TEVAR) or dialysis-dependent patients were excluded. TAAs were true aneurysms in 58 patients, dis-secting in 117, and mycotic in 2. CKD was defined by a preoperative estimated Glomerular Filtration Rate (eGFR) on admission of less than 60 ml/min/1.73m2, with 80 patients being included in Group CKD (GC) and 97 patients in Group normal kidney function (GN). The mean age of GC (73+10 years) was significantly higher than that of GN (63+16 years) (p<0.01). The rate of emergent surgical interventions was similar in GC, 40 (50%) patients, and GN, 42 patients (43%) (p=0.37). Brain and systemic organ protection was established during surgery with selec-tive cerebral perfusion (SCP) and systemic hypothermia under circulatory arrest (CA) at a minimum core body temperature of between 25 and 27 degrees. GR for TAAs was performed by total arch replacement (TAR) in 84 patients, proximal hemi-arch replacement (HAR) in 86, and distal HAR in 7.Results: Operative mortality within 30 days was higher in GC than in GN (10.0% vs 4.1%, p=0.12), and in-hospital mortality was significantly higher in GC (17.5% vs 4.1%, p=0.003) includ-ing emergent cases. However, the incidence of overall major postoperative complications such as early reoperation due to any cause, low output syndrome, lethal arrhythmia, major cerebro-vascular events, mediastinitis, and sepsis was similar between GC and GN (32.5% vs 29.9%, p=0.71). The prevalence of acute renal injury of more than class “injury” in the RIFLE criteria (perioperative serum creatinine increase >2-fold) was similar in both groups (GC:9.1% vs GN:17.2%, p=0.15). However, in a mean follow-up period of 43+44 months among survival patients, a Kaplan-Meier analysis revealed that 1-year and 5-year survival rates were signifi-cantly lower in GC than in GN (76.1% vs 91.8%, 63.2% vs 83.9%) (p=0.003).Conclusions: Although these results demonstrated that CKD may affect clinical outcomes fol-lowing open TAA surgery with hypothermia under CA and play a pivotal role in predicting early and midterm survival, our surgical strategies for TAAs with hypothermia may be accept-able in the era of TEVAR, even for CKD patients. A strict medical follow-up such as optimal medical therapy will be mandatory in order to improve long-term clinical outcomes following surgical interventions. Future evaluations are needed to obtain more precise clinical evidence.

Session Ⅱ-8

Optimal Treatment Strategy for Aortic Arch Aneurysm: Open Repair vs. TEVAR with Branched Stent Graft

M. Kawatou 1, K. Minakata 1, K. Sakamoto 1, J. Tazaki 2, H. Higami 2, T. Nakatsu 1, D. Heima 1, H. Nishio 1, K. Uehara 1, H. Sakaguchi 1, K. Yamazaki 1, T. Ikeda 1, K. Inoue 3, T. Kimura 2, R. Sakata 1

1 Cardiovascular Surgery, Kyoto University, Kyoto, Japan2 Cardiovascular Medicine, Kyoto University, Kyoto, Japan3 PTMC Institute, Kyoto, Japan

OBJECTIVEAlthough open repair is our preference for patients with aortic arch aneurysm, we have often chosen TEVAR with a branched Inoue stent graft (ISG) in high-risk patients. The aim of this study was to evaluate the midterm clinical outcomes of open repair and TEVAR with branched ISG approaches.METHODSBetween 2007 and 2014, we treated 141 patients with aortic arch aneurysm by means of either open repair (n=65, OPEN group) or TEVAR with a branched ISG (n=76, bTEVAR group). Of note, patients undergoing hybrid TEVAR (n=11) were excluded from this study.RESULTSThe mean ages were 70.7±12.4 years in the OPEN group and 73.4±12.1 years in the bTEVAR group (p=0.20). The etiologies included true aneurysm in 110 patients (78.0%), chronic dissection in 28 (19.9%), and pseudoaneurysm in 3 (2.1%).There was 1 in-hospital death in the OPEN group (1.5%) and 3 in the bTEVAR group (4.0%) (p=0.39). In the OPEN group, the early complications included cerebral infarction in 6 (9.2%) patients, graft infection in 3 (4.6%), and aortic dissection in 1 (1.5%). While in the bTEVAR group, the early complica-tions included a type I endoleak in 12 (15.8%) patients, cerebral infarction in 6 (7.9%), delivery failure in 1 (1.3%), and paraplegia in 1 (1.3%). The mean follow-up duration was 3.0±2.0 years with 92% completeness. In the OPEN group, there was only 1 (1.6%) late death related to graft infection, while in the bTEVAR group, there were 4 late deaths, including 3 sudden deaths (4.2%) with unknown causes and 1 (1.4%) due to new aortic dissection. The OPEN group had rela-tively lower 3-year aneurysm-related mortality comparing to that in the bTEVAR group (3.1% vs. 5.4%, p=0.28). In terms of late secondary procedures, there was 1 (1.6%) redo graft replacement and 1 (1.6%) omentum flap for graft infection in the OPEN group. However, there were 9 (12.5%) additional endovascular repairs and 4 (5.3%) open repairs in the bTEVAR group. The OPEN group had a relatively lower 3-year secondary procedure rate comparing to that of the bTEVAR group (6.8% vs. 16.3%, p=0.20).CONCLUSION: Although the open repair provided better early and midterm outcomes, bTEVAR can be performed with low early mortality and acceptable midterm results in high-risk patients.

Session Ⅲ-1

Management of Chronic Type B Dissection

Joseph E. BavariaUniversity of Pennsylvania, Philadelphia, PA, USA

ObjectiveThoracic endovascular aortic repair (TEVAR) has been shown to have survival benefit in patients with complicated type B dissection compared with open surgery or medical therapy. We analyze the impact of timing of intervention from the onset of symptoms to TEVAR, and its relation to complications.MethodsBetween 2005 and 2012, we performed 132 TEVARs for acute and subacute (<6 weeks) type B dissection; 186 other patients were managed with medical therapy only. Patients were followed in a clinical registry. Standard univariate and survival methods were used.ResultsOf the 132 TEVARs for type B dissection, 70 were performed within 48 hours of presentation (Acute-Early); 44 between 48 hours and 14 days from presentation (Acute-Delayed); and 18 between 14 days and 6 weeks of presentation (Subacute). Demographic characteristics were similar among groups. Severe complications were more common in the Early-Acute and Delayed-Acute patients than in the Subacute patients (P = .04) Retrograde type A dissection tended to be more common in the Acute-Early group. Overall survival was similar among groups.ConclusionsDelayed intervention appears to lower the risk of complications of TEVAR for aortic dissection in patients who are stable enough to wait. Among patients initially managed medically, new TEVAR indications were not uncommon, and such patients must be followed closely.

Session Ⅲ-2

Open Thoracoabdominal Aortic Aneurysm Repair: My Approach

Norihiko ShiiyaHamamatsu University School of Medicine, Hamamatsu, Japan

【Objective】 To report my approach of open thoracoabdominal aortic aneurysm repair.【Methods】 Outcomes of 185 patients were retrospectively reviewed, and the impact of indi-vidual components of multidisciplinary approach was analyzed. (Operative technique) A closed-loop femoro-femoral bypass circuit with a soft reservoir bag was used for distal aortic perfusion with heparin reduction. Deep hypothermia was preserved for open aortic anastomosis. Visceral and renal arteries were selectively perfused through a circuit side-arm. (Spinal cord protection) Transcranial motor evoked potentials monitoring, cerebrospinal fluid drainage and continuous naloxone infusion were used. To maximize collateral blood flow during reconstruc-tion, cross-clamping sites and sequence and location of intercostal reconstruction was preoperatively determined according to the information of feeding arteries identified by com-puted tomography. During reconstruction of a solitary hairpin shaped feeding artery, maintaining blood flow to the neighboring intercostal arteries was considered mandatory. This was achieved by preceding reconstruction of a proximal intercostal artery by segmental cross-clamping while the critical artery was perfused through distal aortic perfusion. Separate tube grafts were used for intercostal reconstruction. To improve their patency, a larger (12-mm) graft was recently preferred and was sutured to the aortic wall first, then connected to the main graft to make its length shortest. I recently prefer staged repair, where type II repair was converted to the descending thoracic replacement followed by type III/IV repair, expecting the extra-thoracic collateral pathway development.

【Results】 Hospital mortality was 3.8% and spinal cord injury was 5.4%. Introduction of preop-erative feeding artery identification resulted in reduced number of intercostal reconstruction (2.5 to 1.7) and improved patency (54% to 76%), so that the number of patent arteries was not different. Patency was 91% for the feeding arteries and 70% for non-feeders. Introduction of segmental sequential intercostal reconstruction with a separate graft resulted in decreased incidence of intraoperatively detected spinal cord ischemia (85% to 46%). In the presence of a supplemental distal feeding artery, blocking back-bleeding was sufficient to reverse ischemia. During reconstruction of a solitary hairpin shaped feeding artery, however, it was not effective in 50%. Results of the downstream thoracoabdominal operations after previous descending thoracic replacement was not different (no mortality and spinal cord injury) from the de novo operation.

【Conclusions】 My approach to maximize the spinal cord collateral blood flow seems justified.

Session Ⅲ-3

Thoracoabdominal Aortic Aneurysm: Open or Stent Graft

Edward P. ChenEmory University, Atlana, GA, USA

Thoracoabdominal aortic aneurysms (TAAA) carry a dismal prognosis without surgical inter-vention. The mainstay of management has traditionally been open surgical repair. Improvements in operative technique, circulation management and contemporary techniques for end-organ protection have all resulted in improved outcomes. However, even in high volume centers of excellence where operative mortality can be accomplished with a 2% to 8% risk of death, these procedures are highly morbid and carry significant risks of adverse renal, respiratory and neurologic complications.Thoracic endovascular aortic repair (TEVAR) has been shown to be a safe procedure for distal aortic pathology with a reported operative mortality of less than 5%. From its initial indication for treating atherosclerotic descending thoracic aortic aneurysms, the role of TEVAR has been expanded to include distal aortic dissection and thoracoabdominal aortic replacement. TEVAR has also been associated with significant reductions in renal and neurologic complications associ-ated with open surgical repair and elimination of pulmonary complications by avoidance of an open thoracotomy incision. The reduction in perioperative morbidity and mortality, however, has been offset by a higher reintervention rate when compared with traditional open repair. In addition, the role of TEVAR in the treatment of thoracoabdominal aneurysms in the setting of chronic distal aortic dissection remains unclear.The purpose of this discussion is to review contemporary results of open TAAA repair and to compare those results to the use of TEVAR. Limitations of TEVAR will be discussed, particu-larly in the setting of complex chronic dissection anatomy. Lastly, the important clinical variables for deciding optimal therapy between open repair and TEVAR for TAAA will be reviewed.

Session Ⅲ-4

Mid- and Long-term Results Following Xenopericardial Aortic Tube Grafts to Treat Infections of the Aorta and of Vascular Grafts and Endografts

Thierry P. CarrelUniversity Hospital of Berne, Berne, Switzerland

Objective. Mycotic aneurysm and infection of aortic prosthesis or stent-graft are serious condi-tions that may dramatically affects the patient’s outcome. Mid-term results of xenopericardial aortic tube grafts implanted to treat infected aneurysms, graft or stent-graft infections are presented.Methods. 38 patients with infected aortic aneurysm (n=7), vascular graft (n=24) or endovascular stent-graft (n=7) infection (7 with aorto-esophageal, aorto-bronchial or aorto-duodenal fistula) were treated by complete removal of the infected material, extensive debridement of the sur-rounding tissues as well as orthotopic vascular reconstruction (ascending aorta ± aortic arch n=11 , descending n=14, abdominal n=13) using self-made aortic grafts constructed from a xenopericardial patch. A 14 x 8 cm bovine pericardial patch is sewn to form a tubular neoaorta with a diameter of 2.5 cm and a length of 14 cm. If needed, 2 or more segments were used depending on the individual situation.Results. Perioperative mortality was 15% (6/38). All deaths were due to multiorgan failure and/or uncontrolled septicemia. Average observational follow-up was 48 months (maximal 9 years). Postoperative CT-scans showed regular findings at the surgical sites in all surviving patients. Antibiotic treatment was continued for a mean of 6 months. Freedom from reinfection and redosurgery on the same aortic segment was 96.3% and 92.6%, respectively.Conclusions. Orthotopic reconstruction of the aorta using bovine pericardium tube graft pro-vides excellent hemostasis and durable results in terms of freedom from re-infection and re-operation. This concept represents an interesting and very efficient alternative to homografts and coated grafts in infected aortic diseases.

Session Ⅲ-5

Endovascular Treatment for Thoracoabdominal Aneurysm or Dissection

Masaaki KatoMorinomiya Hospital, Osaka, Japan

OBJECTIVESThere still remains considerable number of mortality and morbidity of surgical repair for tho-racoabdominal aortic aneurysm or dissection (TAAD). As an alternative technique, endovascular thoracoabdominal aneurysm repair (EVTAR) with visceral artery reconstruction has been accepted as a treatment option for severe comorbid patients of TAAD, because there are lim-ited mortality and permissible frequency of major adverse events in this less invasive treatment. We report the results of EVTAR at our hospital with a focus on mortality and morbidity in early phase.METHODSWe analyzed data from 50 consecutive patients with TAAD (mean age, 73±11.2 years; 40 men) who underwent EVTAR with fenestrated and/or branched stent graft at our hospital between June 2010 and March 2015. In all patients, mean systemic blood pressure was maintained at ≥ 80 mmHg. Opioid use was avoided in the perioperative period.RESULTSAccording to the Crawford classification, the graft coverage extent was 4% (2/50) in type I, 42% (21/50) in type II, 26% (13/50) in type III, 20%(10/50) in type IV and 8% (4/50) in type V. In most patients (72%, 36/50), cerebrospinal fluid drainage was done intraoperatively and 1 day postop-eratively. Hospital mortality was 6% (3/50). No patient developed spinal cord injury in the perioperative period. Stroke observed in 1 patient (2 %), respiratory complications occurred in 2 patients (4%). Ischemic colitis observed in 4 patients (8 %) and acute renal failure in 1 patient (2 %).CONCLUSIONSEVTAR may be associated with only a low incidence of morbidity in the perioperative period. Therefore EVTAR is expected to become a promising treatment option for appropriately selected patients with TAAD.

Session Ⅲ-6

Surgical Strategy for Entire Shaggy Aorta

A. Usui, H. Oshima, T. Abe, Y. Araki, Y. Narita, M. MutsugaCardiac Surgery, Nagoya University, Nagoya, Japan

Objective:Severe diffuse arteriosclerosis disease of the entire aorta ranging from the arch to abdominal aorta is defined as entire shaggy aorta. Such a kind of disease is easy to associated with thrombo-embolic complications. Our surgical principle is that aneurysms larger than 6cm are surgical indication and graft replacement is performed only on larger segments over 4 cm principally without aortic cross clamping under deep hypothermic circulatory arrest. We review our clinical experiences to evaluate the feasibility of our surgical strategy.Methods:Twenty-seven surgeries were performed for entire shaggy aorta since 1997 to 2014. It is 3.8% of total 712 cases of thoracic aortic surgeries. There were 22 male and 5 female with average age of 68 +/- 5 years old.Total arch replacement via median sternotomy were performed in 12 cases and frozen elephant trunk (FET) was concomitant in 7 and elephant trunk (ET) was convined in other 5. Extended aortic arch replacement was done via both median sternotomy and left thoracotomy in 7. Thoraco-abdominal aortic repair was done via spiral incision in 5. Debranching of arch vessels with TEVAR (debranching TEVAR) in 3. Except of 3 debranching TEVAR, deep hypothermic circulatory arrest was applied without aortic cross clamping.Results:Major complications were stroke in 7 (26%), paraplegia in 3 (11%), bowel necrosis in 2 (7%), renal failure in 5 (18%). Any major complications occurred in 15 (55%). There were 4 hospital deaths (15%, 2 bowel necrosis, 1 stroke and 1 rupture). All paraplegia were complicated after FET (43%). Stroke was frequently complicated after debranching TEVAR (2 of 3). There were 4 late deaths (15%, 1 stroke, 1 GI bleeding, 1 cancer, 1 rupture) and 4 aortic events (15%, 3 redo, 1 rupture) during follow-up period (4.3 +/- 3.2, 0.1 - 12.6 years). Survival rate and freedom from aortic events at 5 years after surgery were 77 +/- 8% and 94 +/- 6% by the Kaplan-Meier analy-sis, respectively.Conclusions:Any procedure for entire shaggy aorta associated frequently with embolic complications, especially in hybrid procedure with stent graft (FET, debranching TEVAR). Surgical indication should be determined in consideration of high mortality and morbidity balanced with expected natural history. Otherwise aortic non-clamping technique is the only way to rescue patients with entire shaggy aorta.

Session Ⅲ-7

In-hospital and Follow-up Outcomes of Re-operative Repair of Descending Thoracic and Thoracoabdominal Aneurysms

C. Lau, M. Gaudino, M. Munjal, M. Elsayed, L. GirardiDepartment of Cardiothoracic Surgery, Weill Cornell Medical College, New York, NY, USA

Objective. To evaluate the results of re-operation on descending thoracic and thoracoabdominal aneurysms.Methods. From 1997 to 2015, 72 consecutive patients underwent re-operative repair of thoracoab-dominal aneurysms (22 descending thoracic and 50 thoracoabdominal). These patients were compared to 593 contemporary patients who underwent primary repair of corresponding aneu-rysms. Propensity matching was used to neutralize differences in preoperative profile between patients groups. Postoperative survival was assessed using the Kaplan Meier method.Results. Patients undergoing re-operations had a lower mean age (60.3 vs. 65.8 years, p=.002) and higher prevalence of males (70.8% vs. 56.5%, p=.02). The re-operation group had a lower incidence of extent I or II aneurysms (30% vs. 5.3%, p<.001). In the re-operation group 83.3% were repaired using a clamp and sew technique, 13.9% circulatory arrest and 2.8% partial left heart bypass vs. the control group consisting of 62.2% clamp and sew, 8.6% circulatory arrest and 29.2% partial left heart bypass (p<.001). Cerebrospinal fluid drainage was used in 75% of re-operations and 84% in the control group (p=.05). Intercostal reimplantation was performed in 11.1% of re-operations vs. 43.2% of controls (p<.001). Concomitant procedures were performed in 56.9% of re-operations and 28.5% of primary procedures (p<.001). Cold renal perfusion was used in 36.1% of re-operations vs. 19.7% of controls (p=.001). In-hospital mortality was compa-rable between the two series (8.3% in the re-operation group and 5.6% in the pri-mary group, p=.345). The incidence of major postoperative complications was comparable between groups (stroke 0 vs 0.8%, need for tracheostomy 5.6% vs. 8.1%, new dialysis dependent renal failure 6.9% vs 5.1%, spinal cord injury 4.2% vs. 2.9% in the reoperation and primary series respectively, p>.05 for all vari-ables), with the exception of postoperative myocardial infarction (2.8% reoperation vs 5.6% primary, p=.003). Five-year sur-vival was 57.8% in the re-operation group and 55% in the primary surgery group (p=.74). No differences in the in-hospital and follow-up outcomes were found in the propensity matched groups (see Table).Conclusion. Re-operative repair of descending thoracic and thoracoabdomi-nal aneurysms can be safely performed with similar in-hospital and follow-up outcomes compared to primary repair of these aneurysms.

Variable Reoperative Group

Primary Group P value

Number of patients 67 67 naAge (mean, std. dev.) 61.6 ± 15.0 60.5 ± 14.6 .67Male 46 (68.7) 44 (65.7) .71Smoking 48 (71.6) 48 (71.6) NSPrevious coronary revascularization 16 (23.9) 10 (14.9) .19Hypertension 63 (94.0) 65 (97.0) .40Chronic pulmonary disease 25 (37.3) 31 (46.3) .29Previous stroke 6 (9.0) 4 (6.0) .51Peripheral vascular disease 16 (23.9) 15 (22.4) .83Diabetes 7 (10.4) 2 (3.0) .08Family history of aneurysm 4 (6.0) 2 (3.0) .40Renal dysfunction 26 (38.8) 18 (26.9) .14Preoperative spinal cord injury 1 (1.5) 1 (1.5) NSThoracoabdominal aneurysm 49 (73.1) 47 (70.1) .70Extent 1 and 2 15 (30.6) 37 (78.8) <.001Aneurysm size (mm) (mean, std. dev.) 7.3 ± 1.6 6.9 ± 1.4 .09Shock 1 (1.5) 4 (6.0) .17Emergent operation 20 (29.9) 19 (28.4) .84Intraoperative dataClamp and sew 58 (86.6) 34 (50.7) <.001Circulatory arrest 7 (10.4) 7 (10.4)Partial bypass 2 (3.0) 26 (38.8)Spinal drainage 52 (77.6) 54 (80.6) .67Intercostal reimplantation 7 (10.4) 27 (40.3) <.001Concomitant procedures 36 (53.7) 20 (29.9) .005Cold renal perfusion 25 (37.3) 19 (28.4) .27Postoperative dataIn-hospital death 6 (9.0) 3 (4.5) .30Myocardial infarction 2 (3.0) 0 (0.0) .15Stroke 0 (0.0) 1 (1.5) .31Tracheostomy 4 (6.0) 5 (7.5) .73New dialysis 5 (7.5) 6 (9.0) .75Spinal cord injury 2 (3.0) 4 (6.0) .40Revision for bleeding 1 (1.5) 2 (3.0) .55Percentage alive at 5-year follow-up 56.3 62 .38In-hospital and follow-up outcomes in the propensity-matched series (data presented as n (%), unless otherwise noted).

Session Ⅲ-8

Analysis of Aneurysm Diameter in Ruptured Descending or Thoracic-abdominal Aortic Aneurysm

T. Oda, K. Minatoya, H. Sasaki, H. Tanaka, T. Itonaga, Y. Seike, Y. Inoue, J. Kobayashi

National Cerebral and Cardiovascular Center Japan, Osaka, Japan

OBJECTIVES: Surgical indication of the descending or thoracic-abdominal aortic aneurysm in Japan is equal to or more than 55 mm in diameter. In order to verify whether the surgical indication is also appropriate in clinical practice, we retrospectively analyzed the aneurysm diameter of the descending or thoracic-abdominal aortic aneurysm in rupture cases morphologically.METHODS: Between 2007 and 2014, a retrospective review of 45 cases of ruptured descending or thoracic-abdominal aortic aneurysm (mean age, 77.0 ± 9.8, 30 males) were done. There were 31 patients in degenerative aortic aneurysms (fusiform type 20, saccular type 11) and 14 patients in dissecting aortic aneurysms. Patients with acute dissection, mycotic aortic aneurysm and connective tissue disorder were excluded. Co-existing diseases included hypertension in 30 patients, diabetics in 7, hyperlipidemia in 9, and chronic renal failure in 8.RESULTS: All patients underwent emergent operations (graft replacement in 24 patients, stent grafting in 21). Overall hospital mortality rate was 35.6 % (16/45, ruptured degenerative aortic aneurysm: 41.9%, ruptured dissecting aortic aneurysm: 24.4%). Mean ruptured aortic aneurysm diameter was 61.1 ± 10.6 mm. Mean ruptured aortic aneurysm diameter in fusiform type was 67.1 ± 8.1 mm (54 - 85 mm, median 68 mm), in saccular type 59.8 ± 10.1 mm (47-70 mm, median 56 mm) and in dissecting aneurysm 53.5 ± 9.5 mm (36-65 mm, median 65 mm). In 11 patients (24.4%) the aneurysms had ruptured at 55 mm in diameter or smaller (fusiform type in 1/20 patient, saccular type in 3/11, dissecting aortic aneurysm in 7/14). Univariate analysis demon-strated that risk factors for aneurysm rupture was patients with dissecting aortic aneurysms (p = 0.021, odds ratio: 12.667).CONCLUSIONS: Current surgical indication for fusiform type descending or thoracic-abdominal aortic aneurysm was supposed to be appropriate. However, in dissecting aortic aneurysm, 50 % of aneurysms had ruptured at 55mm in diameter or smaller. In the view of recent improvement of aortic surgery, earlier indication of the surgery for dissecting aortic aneurysm should be considered in clinical practice.

Session Ⅳ-1

KEYNOTE SPEAKER: The History of Aortic Surgery

Joseph S. CoselliBaylor College of Medicine, Houston, TX, USA

As late as the early 1950s, replacing sections of aorta to repair aortic aneurysms was not yet a treatment option; instead, the well-accepted treatments were largely palliative, such as cellophane wrapping and endoluminal wiring. In 1952, Cooley and DeBakey published a small series of aortic repairs that included a novel successful repair of a saccular aneurysm by using lateral suture to restore aortic continuity after resection. Interest in replacing fusiform aneurysmal sections of the aorta was piqued by the successful use of homograft replacement in aortic coarctation in the mid-1940s. In 1951, Dubost fully resected and replaced an abdominal aneurysm with a homograft by a retroperitoneal approach. Soon, other surgeons duplicated this achievement; DeBakey did so by using a transperitoneal approach in 1952. In 1953, DeBakey and Cooley successfully resected a DTAA and used a “clamp-and-sew” approach to replace it with a homograft. These early approaches favored full resection of the aneurysm, and tolerance to isch-emia seemed unpredictable and multifactorial. Attempts to repair and replace fusiform aneurysms of the aortic arch began in 1951 but were not successful until DeBakey’s 1957 attempt. Barriers to success included left ventricular strain, atrial fibrillation, and catastrophic cerebral ischemia. Early repair of tho-racoabdominal aortic aneurysms (TAAAs) was likewise complicated by branching vessels and the threat of spinal cord ischemia. Reports of successful repairs emerged in 1955, and in 1956 DeBakey reported 4 such repairs; DeBakey’s early mortality rate was 50%. 　The use of homografts as an arterial substitute was fraught with difficulties, including degeneration, poor availability, and the complexity of preservation techniques. Synthetic arterial substitutes were developed by Voorhees, who had noticed the endothelialization of suture material. Several arterial substi-tutes were used, but Dacron (first used by DeBakey) was deemed most suitable, although graft porosity remained a problem. 　As aortic repair expanded with the greater availability of arterial substitutes, the limits of aortic clamping were tested and sequelae of distal aortic ischemia became a concern. Canine experiments were performed to better understand the role of intercostal and lumbar arteries, which were often disrupted as part of distal aortic repair. In 1960, a novel approach to reduce spinal cord ischemia by using cerebro-spinal fluid (CSF) draining during aortic clamping was introduced by Miyamoto and colleagues from the Tokyo University School of Medicine, who reported their experience in an experimental canine model and in 2 clinical cases. Since this time, CSF drainage has become the most widely used surgical adjunct to prevent paraplegia following aortic repair.　In the next decade, aneurysm resection and replacement often used an extra-anatomic approach. In the 1970s, Crawford popularized in situ techniques, particularly in the repair of TAAAs, drawing on the work of Carrel and Guthrie ,Javid, and Spencer. Crawford used an anatomic endovascular graft inclusion technique, reimplanted patches of intercostal arteries to better perfuse the spinal cord, reattached the visceral arteries as an island to a oval opening made in the graft, and avoided fully resecting the aneu-rysm, instead wrapping the remaining wall around the replacement graft. Thus, Crawford improved early survival to 92%.　In the late 1970s and into the 1980s, repair of the aortic arch expanded as new techniques were added. In 1975, Griepp repurposed the technique of profound hypothermia that he and others used in early cardiac transplantation and applied it to the aortic arch. In 1981, Cooley and Livesay reported the open distal anastomosis technique to reduce trauma to the arch from clamping as well as to aid in visual inspection in cases of aortic dissection. In the late 1980s, Ueda reported on the use of retrograde cerebral perfusion to aid cerebral perfusion during aortic arch repair and remove emboli. Soon, this was followed by efforts from Kazui as he introduced modern antegrade cerebral perfusion that was greatly facilitated by the introduction of flexible catheters in Japan.　Endovascular aortic repair, first used in Russia by Volodos in the late 1980s and envisioned experimen-tally by Dotter a decade previously, was popularized by Parodi and Dake in the early 1990s. In Japan, both Kato and Inoue made substantial contributions by introducing the hybrid frozen elephant trunk approach and fully endovascular repair of the aortic arch. Today, numerous endovascular approaches are being developed to treat all aspects of aortic disease. Likewise, attempts to standardize and rigorously evaluate surgical approaches will no doubt improve care for many patients. Innovation on both endovas-cular and surgical front-lines will ensure superior care for tomorrow’s patients.

Session Ⅳ-2

Early and Late Complications after Aortic Arch Hybrid Repair

T. Shibata 1, K. Morishita 1, T. Baba 1, T. Saga 1, K. Narayama 1, T. Mawatari 21 Department of Cardiovascular Surgery, Hakodate Municipal Hospital, Hakodate, Japan2 Department of General Thoracic Surgery, Hakodate Municipal Hospital, Hakodate, Japan

Objective:Despite the evolution of technology, aortic arch aneurysm repairs remain challenging in high-surgical-risk patients. Recently, hybrid arch repair (debranching + TEVAR) has emerged as a potentially less invasive treatment. However, some reports showed that it was still associated with a considerable morbidity and mortality. The aim of this study was to analyze our results of hybrid aortic arch repair focusing on early and late complications.Methods:From May 2008 to April 2015, 113 patients underwent hybrid arch repairs. The mean age was 74 years (range, 36-89 years), and 89 patients (79%) were men. Indications included degenerative aneurysm (92 patients), dissection (11), and congenital aneurysm (2). Nine patients underwent emergency repair due to rupture. The mean aneurysm size was 57±13 mm. The rerouting procedures consisted of isolated left subclavian revascularization (64 patients), complete deb-ranching (28), two debranching (19), and extrathoracic debranching (2). Recently, surgeon-modified fenestrated technique was used in 6 patients to extend proximal neck length (Figure). Thirteen patients had mini-J shaped sternotomy. Debranching and staged TEVAR has been performed in 42 patients (37%). JapanScore (cardiac operative risk evaluation from the Japanese database) was 16%±17%. Follow-up averaged 23±17 months.Results:The 30-day mortality was 2.7% (3/113 patients). Four patients had access site injury. Three of the patients required interventions. Persistent neurologic deficits occurred in 4 patients and spinal cord injury in 2. Respiratory complications included prolonged ventilation longer than 3 days in 3 patients and tracheal reintubation in 1. Aortic dissection was observed in 1 patient, which led to lethal occlusion of the celiac trunk and super mesenteric artery. Two patients experienced bypass graft occlusion without neurologic complications. Persistent endoleaks at 1 year was noted in 11% (9/80) of patients. Five patients required re-TEVAR because of progres-sive dilatation (3 patients), stent fracture (1), and rupture (1). There were no open surgical conversions. Four aneurysm-related deaths occurred during follow-up period. Cases of these deaths included stent graft infection, undiagnosed aortopulmonary fistula, and complicated type B aortic dis-section. One patient refused a further operation. Kaplan Meier 1-year, 3-year, and 5-year survival rates were 85%±4%, 69%±6%, and 50%±11%, respectively.Conclusions:Hybrid arch repairs can successfully reduce postoperative mortality in high-surgical-risk patients. However, these procedures are associated with significant complication rates. Therefore, we recommend performing hybrid arch repairs in highly experienced centers.

Session Ⅳ-3

Patient-specific Fluid Dynamics - A New Diagnostic Tool for Assessment of the Thoracic Aorta?

P. Youssefi 1, A. Gomez 2, R. Sharma 3, A. Figueroa 4, M. Jahangiri 11 Department of Cardiothoracic Surgery, St. George’s Hospital, London, United Kingdom2 Department of Biomedical Engineering, King’s College London, London, United Kingdom3 Department of Cardiology, St. George’s Hospital, London, United Kingdom4 Computational Vascular Biomechanics Lab, University of Michigan, Ann Arbor, MI, USA

OBJECTIVE(S)Current intervention criteria for the thoracic aorta concentrate on size. However the complexity of aortic disease is not fully exposed by aortic dimensions alone, and morbidity or mortality can occur before intervention thresholds are met. Computational fluid dynamics (CFD) is a non-invasive approach to quantify haemodynamics in assessment of aneurysms and rupture risk.Wall shear stress (WSS) measuring viscous shearing forces on the endothelium, and oscillatory shear index (OSI) measuring disturbed flow, are a pathophysiological stimulus to gene expression, extracellular-matrix remodelling, and aortic wall thinning.To date, CFD has been performed using assumptions of inflow and outflow conditions. The key to implementing this tool in clinical practice is to carry out CFD in a completely patient-specific manner.We aimed to evaluate the efficacy of a new patient-specific approach to CFD of the thoracic aorta, and its functional and haemodynamic indices in assessment of aortic pathology.METHODS45 patients underwent magnetic resonance angiography (MRA) of the thoracic aorta, and phase-contrast-MRI (PC-MRI) above the aortic valve. Three-dimensional aorta models were constructed from MRA data and discretized to form a finite element mesh. The 3D velocity profile from PC-MRI was mapped onto the inflow mesh, allowing prescription of patient-specific inflow boundary conditions. Blood pressure, cardiac output, and cross-sectional area of each vessel were processed to assign outflow boundary conditions to arch vessels and descending aorta.RESULTSCFD enabled measurement of WSS throughout the thoracic aorta. WSS was significantly elevated in aortic stenosis, highest in bicuspid morphology with right-non cusp fusion (mean WSS=37.1±4.0dyn/cm2, compared to 19.9±1.9dyn/cm2 for bicuspid right-left fusion, 25.7±1.2dyn/cm2 in tricuspid aortic stenosis, 12.3±3.4dyn/cm2 in aortic insufficiency, and 9.9±5.4dyn/cm2 in healthy volunteers, p<0.05). Aortic stenosis patients displayed asymmetrical WSS distributions, the greater curvature experiencing the highest WSS. OSI was lower in bicuspid right-non fusion (p<0.05).Eccentricity of flow was higher in bicuspid patients (Flowasymmetry= 84.1±5.4%, compared to 28.1±21.5 for tricuspids, p<0.05). Helicity of flow was assessed by the Helical Flow Index (HFI), which was higher in bicuspid right-left fusion (HFIsystole= 0.39±0.04, compared to 0.28±0.03 for all others, p<0.05).CONCLUSIONSThis new approach to CFD allows for prescription of patient-specific inflow profiles, 3D aortic geometry, and outflow conditions based on patient haemodynamics. This permits detailed functional assessment of the thoracic aorta in a non-invasive manner. Patients with bicuspid aortic valves displayed eccentric flow patterns with high helic-ity. Aortic stenosis (tricuspid or bicuspid) led to higher wall shear stress in the greater curve of the ascending aorta. Further work in this field may enable implementation of these haemodynamic indices in diagnostic assessment of the thoracic aorta, and may form part of intervention criteria.

Session Ⅳ-4

Impact of Synchrotron Radiation Based Phase-contrast X-ray CT Findings on Understanding Onset of Acute Aortic Dissection

T. Tsukube 1, N. Yagi 2, M. Hoshino 2, Y. Nakashima 3, K. Nakagawa 4, Y. Okada 1, T. Haraguchi 1, M. Yoshida 5, N. Mukohara 5, S. Kozawa 1, K. Ogawa 1, Y. Okita 6

1 Cardiovascular Surgery, Japanese Red Cross Kobe Hospital, Kobe, Japan2 Research & Utilization Division, Japan Synchrotron Radiation Research Institute / SPring-8, Sayo, Japan

3 Clinical Pathology, Japanese Red Cross Fukuoka Hospital, Fukuoka, Japan4 Pathophysiological and Experimental Pathology, Kyushu University, Graduate School of Medicine, Fukuoka, Japan

5 Cardiovascular Surgery, Hyogo Brain and Heart Center, Himeji, Japan6 Cardiovascular Surgery, Kobe University, Graduate School of Medicine, Kobe, Japan

OBJECTIVES: To investigate pathogenesis of aortic dissection, we have applied phase-contrast X-ray micro-tomography imaging (PCXI) at Japan Synchrotron Radiation Research Institute (SPring-8) for providing detailed visualization of aortic wall structures of the excised aorta. PCXI at SPring-8 is approximately 1000 times more sensitive than absorption-contrast X-ray imaging, which typically produces a poor image contrast for soft tissues. Moreover, dynamic PCXI has been developed to visualize CT image of aortic wall under various tensile force, and this method could simulate physi-ological condition, in which aortic wall is stretched by blood pressure.METHODS: Formalin-fixed human aortic walls, including aortic dissection (group-A: n=10), Marfan syndrome (group-M: n=3), and normal aorta (group-N: n=3) were obtained and ex-vivo PCXI and histological analysis were performed. Then, fresh human aortic walls of aortic dissection (group-F: n=5) were obtained, and dynamic PCXI and histological analysis were performed subsequently.RESULTS: In group-N, PCXI demonstrated tissue densities of the media were homogeneous; tissue densities were not significantly different between intimal side and adventitial side. On contrast, in group-M, PCXI demonstrated statistically significant differences in tissue densities within tunica media. Tissue densities of intimal side were significantly higher than tissue densities of adventitial side, and between intimal side and adventitial side, PCXI demonstrated low density zone in the middle of the tunica media, which correlated with distribution of elastic fibers and existence of cystic medial necrosis in pathological examinations (Image-1). Image-1 demonstrated formalin-fixed surgical sample (A), Elastica van Gieson (EVG) stain (B), high magnitude of EVG stain (C), 3D imaging of PCXI (D), 2D imaging of PCXI (E), and higher magnification of figure E (F). In group-A, PCXI revealed differences in tissue densities in the media; tissue densities were significantly different between intimal side and adventitial side, which well correlated with irregularity of the elastic layers and line of dissection. These findings were also observed in fresh samples of aortic dissection (group-F). With dynamic PCXI, tissue density of fresh aortic wall were significantly increased with elevation of tensile force of the aortic wall, and differences in tissue densities in the media were clearly observed then.CONCLUSIONS: These findings demonstrated that synchrotron radiation based phase-contrast X-ray micro-tomography imag-ing could be a strong modality to understand aortic structures and pathogenesis of the aortic dissection.