It is generally accepted that emergency repair is the

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1 Role of Biologic Glue Repair of Proximal Aortic Dissection in the Development of Early and Midterm Redissection of the Aortic Root Teruhisa Kazui, MD, Naoki Washiyama, MD, Abul Hasan Muhammad Bashar, MBBS, Hitoshi Terada, MD, Kazuchika Suzuki, MD, Katsushi Yamashita, MD, and Makoto Takinami, MD First Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan Background. Redissection of the aortic root after supracommissural aortic graft replacement with reapproximation of the layers of the dissected aortic root is relatively rare. Causes and surgical treatment of this lesion remain controversial. Methods. From January 1983 to September 2000, 130 patients had emergency operation for acute type A aortic dissection. Of them, 57 patients underwent root reconstruction using biologic glues and 4 patients (7.0%) developed redissection of the aortic root associated with moderate to severe aortic regurgitation 5 to 27 months after the initial operation. In all patients, the proximal false lumen was obliterated with infusion of gelatinresorcinol-formaldehyde (GRF) glue or BioGlue and the aorta was reinforced with Teflon felt strip or Surgicel placed on its outside wall. Results. During reoperation, the noncoronary aortic sinus was found to be redissected in all patients with the dissection extending retrogradely to the aortic annulus. This resulted in aortic regurgitation with prolapse of the noncoronary cusp because the proximal suture line dehisced. Histopathology showed disappearance of the nuclei of the medial smooth muscle cells, suggesting tissue necrosis at the site of GRF glue application. The lesions were treated successfully with full root replacement using a freestyle heterograft bioprosthesis or a composite graft prosthesis. Conclusions. The use of biologic glues for reapproximating the layers of the dissected aortic root is associated with a certain amount of risk of aortic wall necrosis. Therefore, care should be taken to ensure proper use of these glues. Full root replacement could be a preferable technique for treating redissection of the aortic root. (Ann Thorac Surg 2001;72:509 14) 2001 by The Society of Thoracic Surgeons It is generally accepted that emergency repair is the treatment of choice for acute type A aortic dissection to prevent fatal intrapericardial rupture during the acute stage. The dissection process may originate from a primary intimal tear located in the ascending aorta often extending retrogradely into the aortic root. This pathologic process destroys the integrity of the aortic root resulting in its rupture, aortic regurgitation (AR), or compromise of the coronary circulation. Therefore, it is necessary to reconstruct the aortic root in most cases of acute type A aortic dissection. Conventionally, the aortic root is reconstructed by reapproximation of the dissected aortic layers with polytetrafluoroethylene (Teflon, Du- Pont, Parkersburg, WV) felt reinforcement and aortic valve resuspension if necessary [1 5]. Biologic glues such as gelatin-resorcinol-formaldehyde (GRF) glue (Cardial, Technopole, Sainte-Etienne, France) [6 9], Fibrin-glue (Aventis Behring GmbH, Marburg, Germany), and more recently, BioGlue (Cryolife International, Inc, Kennesaw, GA) have been used to secure graft anastomoses in an Accepted for publication April 17, Address reprint requests to Dr Kazui, First Department of Surgery, Hamamatsu University School of Medicine, Handayama, Hamamatsu, Japan, ; tkazui@hama-med.ac.jp. aorta that has become fragile as a result of the dissection process. The incidence of redissection of the aortic root after supracommissural aortic graft replacement with obliteration of the proximal false lumen with or without biologic glue has varied among institutes [2 14]. The causes and surgical treatment of this lesion remain controversial. The purpose of this study was to present our clinical experience with redissection of the aortic root, particularly that related to biologic glue. Material and Methods From January 1983 to September 2000, 130 consecutive patients underwent emergency surgical treatment for acute type A aortic dissection. Surgical techniques used in this series principally consisted of resection of the aorta containing the primary intimal tear whenever feasible, obliteration of the false lumen, and interposition of an artificial graft to restore blood flow into the true lumen. From January 1983 to June 1994, the false lumen was routinely obliterated by Teflon felt strip reinforcements of both the inside and outside walls of the aorta. Since August 1994, GRF glue has been used in 53 patients to obliterate the false lumen and reinforce the aortic 2001 by The Society of Thoracic Surgeons /01/$20.00 Published by Elsevier Science Inc PII S (01)

2 510 KAZUI ET AL Ann Thorac Surg REDISSECTION OF THE AORTIC ROOT 2001;72: layers. More recently, Bioglue, formulated from 45% bovine serum albumin and 10% glutaraldehyde, has been used with a similar purpose in another 4 patients. The present study involved a review of these 57 patients who had aortic root reconstruction using the biologic glues. There were 38 men and 19 women with a mean age of years. Two patients (3.5%) had typical Marfan syndrome. Two patients had undergone previous cardiac operation: 1 had coronary artery bypass grafting (CABG) and aortic valve replacement and the other had CABG only. Three patients had undergone previous aortic operation: 2 had abdominal aortic replacement and the other had axillofemoral bypass grafting. Preoperative risk factors included hypoperfusion (shock) in 15 patients (26.3%), cardiac tamponade in 16 (28.1%), myocardial ischemia in 6 (10.5%), renal/ mesenteric ischemia in 1 (1.8%), leg ischemia in 3 (5.3%), cerebral ischemia in 6 (10.5%), and renal dysfunction in 2 (3.5%) with 1 requiring hemodialysis. Operative Technique All operations were performed within 14 days from the onset of acute aortic dissection. The techniques of reinforcing the dissected aortic layers using biologic glues were as follows. For proximal aortic reconstruction, the ascending aorta was transected immediately above the aortic commissure. Aortic regurgitation caused by commissural detachment during the dissection process was mostly repaired with resuspension of the aortic commissures using mainly 4-0 polypropylene sutures with Teflon pledgets placed on both the inner and outer side of the aorta. Then GRF glue was infused into the proximal false lumen after drying the lumen by removing blood and clots. The layers of the aortic wall were then compressed with a special clamp [15] for 5 minutes to allow polymerization of the glue. Teflon felt strips were placed on the outer surface of the aorta for reinforcement using 4-0 polypropylene running sutures. BioGlue was used in an essentially similar fashion except that the dissected aortic wall was not clamped for compression, and the external aortic wall was reinforced with Surgicel (Ethicon Inc, Somerville, NJ) instead of Teflon felt strip. Having completed the proximal aortic reconstruction, systemic circulatory arrest was induced and distal aortic reconstruction was performed. For the latter, an essentially similar technique was used to reapproximate the dissected aortic layers in the case of ascending aorta replacement or hemiarch replacement, whereas a different technique was used in the case of concomitant total arch replacement (TAR). The detail of our TAR techniques has been described previously [16]. Briefly, the technique used in concomitant TAR cases was as follows: The descending aorta distal to the origin of the left subclavian artery was completely transected. Running 5-0 polypropylene suture was placed circumferentially on the descending aorta 1 cm below the aortic stump to prevent dislodgment of biologic glue. Then biologic glue was infused into the false lumen. After reinforcing the outer side of the aorta with a Teflon felt strip, the false lumen was obliterated in a sandwich-like fashion. After the distal aortic reconstruction was completed, a Hemashield graft (Boston Scientific, Natick, MA) was anastomosed to the distal aortic stump, antegrade systemic perfusion from the side arm of the main graft was started, and then the proximal side of the graft was anastomosed to the proximal aortic stump in the same way as the distal anastomosis. GRF glue was used to reinforce the dissected aortic layers of both proximal and distal anastomotic sites in 47 patients, and only the distal anastomotic site in 6 patients. BioGlue was used to reinforce the dissected aortic layers of both the proximal and distal anastomotic sites in the most recent 4 patients. Aortic valve resuspension was performed in 22 patients (38.6%) with AR caused by commissural detachment, and composite graft replacement in 6 patients (10.5%) with annuloaortic ectasia. The extent of distal aortic replacement was ascending only in 4 patients (7%), ascending and proximal portion of the aortic arch in 10 (17.5%), and the whole aortic arch in 43 (75.4%). Indications for TAR in this series were intimal tear in the aortic arch, intimal tear in the descending aorta, rupture or massive false lumen of the aortic arch, compromised arch vessels, coexistent arch aneurysm, and young age, particularly in patients who had Marfan syndrome without serious preoperative complications. Total arch replacement was performed using antegrade selective cerebral perfusion as the cerebral protection technique, the details of which were described previously [16]. Concomitant procedures included CABG in 2 patients (3.5%), mitral annuloplasty in 1 (1.8%), and Doty s extended aortoplasty for supravalvular aortic stenosis in 1 (1.8%). Follow-up The patients were followed up until December 2000 at the outpatient clinic or were contacted by telephone or letter. The follow-up was 100% complete. The mean follow-up duration was months. Statistical Analysis Continuous data are expressed as mean standard deviation. Fisher s exact test was used to compare inhospital mortality between patients receiving aortic root reconstruction with glue and those without glue. Actuarial patient survival and freedom from reoperation were estimated by Kaplan Meier method. Results Survival The overall in-hospital mortality was 10.5% (6 of 57 patients). There was no significant difference in the in-hospital mortality between the ascending and hemiarch replacement group (2 of 14, 14.3%) and the TAR group (4 of 43, 9.3%). Causes of in-hospital mortality were myocardial infarction as a result of dissection in 2 patients, hemorrhage in 1, low cardiac output in 1, suture line rupture due to infection in 1, and late cardiac tamponade in 1. No patient died in the late postoperative

3 Ann Thorac Surg KAZUI ET AL 2001;72: REDISSECTION OF THE AORTIC ROOT 511 period. Survival for all patients at 1, 3, and 5 years after the operation including the in-hospital mortality were 89.4% 4.1%, 89.4% 4.1%, and 89.4% 4.1%, respectively. Reoperations A total of 12 reoperative procedures were performed in 10 patients for proximal and distal aortic lesions. In 5 of these patients, reoperation was done for proximal aortic lesions, 4 (GRF glue in 3 patients and BioGlue in 1) for redissection of the aortic root associated with moderate to severe AR, and 1 (BioGlue) for pseudoaneurysm formation in the proximal graft anastomotic site. None of these patients had Marfan syndrome. Table 1 shows the profile of patients who developed redissection of the aortic root. In these patients, AR caused by commissural detachment was either absent or only occasionally present in a mild form and there was no dilated aortic root at the initial operation. All these patients underwent reconstruction of the aortic root using biologic glues and supracommissural ascending aortic replacement with TAR or partial arch replacement at the initial operation and had an uneventful postoperative course. Digital subtraction angiography and computed tomography scan taken 1 month postoperatively confirmed satisfactory reconstruction of aortic root, ascending aorta, and aortic arch in all patients. However, they developed redissection of the aortic root with AR and required reoperation 5 to 27 months after the initial operation (Fig 1). At reoperation, intraoperative findings in all patients indicated that the aortic root was redissected at the site where biologic glues had been used previously. The noncoronary aortic sinus was redissected with the dissection extending retrogradely to the aortic annulus, resulting in AR with prolapse of the noncoronary cusp because of the dehiscence of the proximal suture line. Macroscopically, the redissected intima appeared brownish or necrotic in 3 patients. Histopathology of the inner wall of the redissected aortic root at the site of the GRF glue application showed almost a complete disappearance of the nuclei of the medial smooth muscle cells and hemosiderin deposition on the false lumenal side of the media on hematoxylin and eosin staining (Fig 2). The medial elastic lamellae at the false lumenal side appeared disrupted on Elastica van Gieson staining. Focal disruption of the elastic lamellae was also observed on the inner side of the wall. However, neither cystic degeneration nor inflammatory change was found there. At reoperation, because of extensive dissection, aortic root replacement using the Carrel button technique was performed using the Freestyle aortic root bioprosthesis (Medtronic, Inc, Minneapolis, MN) in 2 patients (Fig 3) and a composite graft prosthesis made of 24- or 26-mm Hemashield graft (Boston Scientific, Natick, MA) and 23-mm SJM valve prostheses (St. Jude Medical Inc, St. Paul, MN) in 2 patients. One patient who had partial arch replacement underwent concomitant TAR because of an Table 1. Profile of Patients Who Developed Redissection of the Aortic Root After Reconstruction of the Aortic Root Using Biologic Glues Indications for Reoperation Reoperation Results Time Interval (months) Biologic Glues Primary Intimal Tear Initial Operation Classification Stanford/DeBakey AR Age/ Sex Case No. GRF 17 Redissection AR IV ARR with freestyle Bioprosthesis 1 76/F Type A/I I Arch A/V suspension, TAR elephant trunk 2 57/M Type A/I 0 Ascending PAR GRF 27 Redissection AR III ARR with composite graft (24 mm Hemashield 23 mm SJM), TAR TAAGR GRF 9 Redissection AR IV ARR with freestyle Bioprosthesis 3 62/F Type A/I II Unknown A/V suspension, TAR elephant trunk DAGR ARR with composite graft (26 mm Hemashield 23mm SJM) BioGlue 5 Pseudoaneurysm Redissection, AR III 4 47/M Type A/I II Arch A/V suspension, TAR elephant trunk AR aortic regurgitation; ARR aortic root replacement; A/V aortic valve; DAGR descending aortic graft replacement; F female; GRF gelatin-resorcinol-formaldehyde; M male; PAR partial arch replacement; SJM St. Jude Medical; TAAGR total thoracoabdominal aortic graft replacement; TAR total arch replacement.

4 512 KAZUI ET AL Ann Thorac Surg REDISSECTION OF THE AORTIC ROOT 2001;72: Fig 1. Preoperative cineangiogram of a patient (case 1) showing aortic root redissection with severe aortic regurgitation. accidental injury to a branch of the previous arch graft that could not be repaired more conservatively. Figure 4 shows freedom from reoperation estimated by the Kaplan Meier method. Freedom from reoperation for proximal aortic lesions in all patients who were discharged from the hospital were 97.9% 2.1%, 89.7% 5.0%, and 89.7% 5.0% at 1, 3, and 5 years after operation, respectively. Two patients who required aortic root replacement for redissection underwent a third operation for aneurysmal dilation of the distal descending aorta: one had total thoracoabdominal aortic replacement and the other descending thoracic aortic replacement. In both, the distal Fig 3. Postoperative digital subtraction angiogram of a patient (case 1) shows satisfactory reconstruction of the aortic root with a Freestyle Aortic Root Bioprosthesis (Medtronic, Inc, Minneapolis, MN). aortic anastomosis of the second operation was found intact. Another 5 patients underwent reoperation for aneurysm formation of the false lumen in the descending aorta. In these patients and in 3 others who had previous elephant trunk procedure, unusual macroscopic and microscopic findings like those at the proximal anastomotic site were not found at the distal anastomotic site. Comment Although it is generally recognized that the disintegration of the aortic root as a result of aortic dissection Fig 2. Photomicrograph showing inner wall of the redissected aortic root at the site of the gelatin-resorcinol-formaldehyde glue application. Nuclei of the medial smooth muscle cells have mostly disappeared (black arrows) and the false luminal side of the media shows considerable hemosiderin deposition (white arrows). (Hematoxylin and eosin stain, original magnification 13.2.) Fig 4. Actuarial reoperation event-free curve for proximal aortic lesions in patients who were discharged from the hospital.

5 Ann Thorac Surg KAZUI ET AL 2001;72: REDISSECTION OF THE AORTIC ROOT 513 should be corrected in most patients with acute type A aortic dissection, the surgical technique to be used for aortic root reconstruction remains controversial. According to the pathologic condition of the aortic root and surgeon s preference, various techniques such as aortic root repair with either Teflon felt or biologic glue, aortic valve replacement and supracommissural aortic replacement, composite graft replacement of the aortic valve and the aortic root, and more recently valve-sparing aortic root replacement [17, 18] either by David s reimplantation technique or Yacoub s remodeling technique, have been used. Conventionally, the aortic root is reconstructed by aortic valve resuspension in 70% to 80% cases of AR in acute dissection [2, 3, 7, 10], and obliteration of the proximal false lumen mostly reinforced with Teflon felt if the aortic root is not dilated and the aortic valve is normal. However, about 20% of the patients who received this aortic root repair required aortic valve replacement 10 years postoperatively [1, 2, 10]. In 1977, Guilmet and colleagues [19] first applied GRF glue in aortic root reconstruction to reinforce the aorta rendered fragile by the acute dissection and to strengthen the aortic anastomosis. Since then, GRF glue, sometimes referred to as the French glue, has been widely used in the treatment of acute aortic dissection, and its usefulness has been validated [4, 6 9]. In 1994, we started using GRF glue to reconstruct the aortic stump in cases of acute aortic dissection. Despite some practical difficulties in comparing the surgical outcome of different patient cohorts reported in the literature, we noticed an improvement in the survival rate of these patients when compared with that of those who had Teflon repair. In-hospital mortality in patients who received aortic root reconstruction without biologic glue was 23% compared with only 10.5% in those who had glue reconstruction. However, no significant difference was noted in terms of reoperation event-free rate for proximal and distal aortic lesions in the late postoperative period between these two groups. It has been reported that 10% to 40% of patients who were treated with aortic root reconstruction using GRF glue developed recurrence of AR and required reoperation in the late postoperative period [3, 7, 10 12]. Recently, Fukunaga and colleagues [12] reported that 9 of 148 patients treated with GRF glue required reoperation and 7 patients had aortic root redissection related to GRF glue. Macroscopically, the tissue treated with GRF glue appeared necrotic; microscopically, medial degeneration was found in 2 patients. They speculated that complications associated with the GRF glue are likely to be caused by the toxic effect of its formalin component. In our series, macroscopic findings were similar and microscopically, nuclei of the medial smooth muscle cells had mostly disappeared, suggesting necrosis of these cells. It is necessary to use appropriate surgical and glue application techniques to obtain the desired effect of the glue. Measures such as warming (45 C) the gelatinresorcin mixture, drying the tissue surface, applying pressure, allowing time for polymerization, and avoiding formalin overdose [8] have been recommended [20]. While using the GRF glue, we have paid special attention to these points. There are multiple causes for reoperation after aortic root reconstruction. Casselman and coworkers [14] reported that risk factors for reoperation were the use of fibrinous glue and the presence of a dilated aortic annulus (larger than 27 mm), whereas Pessotto and coworkers [13] found preoperative moderate to severe AR to be a factor of increased risk for recurrent AR. Judging from the clinical and pathologic findings, we speculate that the aortic root redissection in the present series was due to formalin overdose or inadequate mixing of the glue components. A similar redissection in the downstream aorta was not seen in this series. Reasons might have been a lesser hemodynamic stress on the distal aorta or obliteration and reinforcement of the distal false lumen with our modified elephant trunk technique. More recently, BioGlue made from bovine serum albumin and less toxic glutaraldehyde has been used in clinical trials in Japan. Earlier, it was reported that Bioglue was useful in repairing acute aortic dissection in a sheep model [21]. We have used BioGlue as an alternative to GRF glue to strengthen the aortic stump. As with GRF glue application, care should be taken to ensure the tissue surface is dry and bloodless. Moreover, pressure should not be applied using surgical forceps because it may cause this less sticky substance to spill out from the false lumen and produce a less effective adhesion. Although glutaraldehyde is less toxic to human tissue than formalin, its overdose may still cause tissue necrosis. Aortic root replacement using composite graft prosthesis has been described as a radical treatment for acute type A dissection associated with annuloaortic ectasia [22]. However, this technique is not suitable when the aortic annulus is of an average size. More recently, favorable midterm results of valve-sparing aortic root replacement for acute type A aortic dissection have been reported [17, 18]. Although these procedures seem to be offering a more radical treatment, they are more technically demanding than the conventional aortic root reconstruction, particularly in critically ill patients. Moreover, further follow-up will be necessary to assess the recurrence of AR. If the dissection process mainly involves the noncoronary sinus, our current approach is to obliterate the false lumen on either side of the noncoronary sinus with glue and then resect the sinus, leaving a rim of about 5 mm above the valve leaflet, and transect the ascending aorta horizontally above the right and left coronary sinuses. A woven Dacron (Boston Scientific, Natick, MA) graft tailored in a scallop-shaped configuration to match the noncoronary sinus is then anastomosed to the proximal aortic stump [23]. This partial remodeling technique is much easier than usual remodeling or reimplantation of the aortic root because coronary reimplantation is not necessary. Indications of reoperation for aortic root redissection in our series included marked dilation of aortic root and

6 514 KAZUI ET AL Ann Thorac Surg REDISSECTION OF THE AORTIC ROOT 2001;72: relatively prompt progression from moderate to severe AR. The operative technique used for aortic root redissection was aortic root replacement with coronary reimplantation. Freestyle aortic root bioprosthesis, which has recently become available as a conduit for aortic root replacement [24], was used in patients older than 70 years of age or in elderly patients who will require total thoracoabdominal aortic replacement because no anticoagulation is necessary and its hemodynamic function is superior. In conclusion, aortic root reconstruction using biologic glue for treating acute type A aortic dissection is associated with a certain amount of risk of aortic wall necrosis and subsequent redissection of the aortic root. Although these complications can usually be treated by available surgical means, further improvements in the quality of glues and their application technique will be necessary to prevent problems in the first place. References 1. Svensson LG, Crawford ES, Hess KR, Coselli JS, Safi HG. Dissection of the aorta and dissecting aortic aneurysms. Improving early and long-term surgical results. Circulation 1990;82(Suppl IV):IV Fann JI, Glower DD, Miller DC, et al. Preservation of aortic valve in type A aortic dissection complicated by aortic regurgitation. J Thorac Cardiovasc Surg 1991;102: Von Segesser LK, Lorenzetti E, Lachat M, et al. Aortic valve preservation in type A aortic dissection: is it sound? J Thorac Cardiovasc Surg 1996;111: Niederhäuser U, Kunzli A, Seifert B, et al. Conservative treatment of the aortic root in acute type A dissection. Eur J Cardiothorac Surg 1999; 15: Sabik J, Lytle W, Bladcstone EM, McCarthy M, Loop FD, Cosgrove D. Long-term effectiveness of operations for ascending aortic dissections. J Thorac Cardiovasc Surg 2000; 119: Lass J, Jurmann MJ, Heinemann M, Borst HG. Advance in aortic arch surgery. Ann Thorac Surg 1992;53: Weinschelbaum EE, Schamun C, Caramutti V, Tacchi H, Cors J, Favaloro RG. Surgical treatment of acute type A dissecting aneurysm with preservation of the native aortic valve and use of biologic glue. Follow-up to 6 years. J Thorac Cardiovasc Surg 1992;103: Bachet J, Goudot B, Dreyfus G, et al. The proper use of Glue. A 20-year experience with the GRF glue in acute aortic dissection. J Card Surg 1997;12: Westaby S, Katsumata T, Freitas E. Aortic valve conservation in acute type A dissection. Ann Thorac Surg 1997;64: Mazzucotelli JR, Deleuze PH, Baufrenton C, et al. Preservation of the aortic valve in acute aortic dissection: long-term echocardiographic assessment and clinical outcome. Ann Thorac Surg 1993;55: Bingley JA, Gardner MAH, Srafford EG, et al. Late complications of tissue glues in aortic surgery. Ann Thorac Surg 2000;69: Fukunaga S, Karck M, Harringer W, Cremer J, Rhein C, Haverich A. The use of gelatin-resorcine-formalin glue in acute aortic dissection type A. Eur J Cardiothorac Surg 1999; 15: Pessotto R, Santini F, Pugliese P, et al. Prevention of the aortic valve in type A dissection complicated by aortic regurgitation. Ann Thorac Surg 1999;67: Casselman FP, Tan ESH, Vermeulen EE, Kelder JC, Morshuis WJ, Schepens MAAM. Durability of aortic valve preservation and root reconstruction in acute type A aortic dissection. Ann Thorac Surg 2000;70: Borst HG, Laas L, Buehner B. Efficient tissue gluing in aortic dissection. Eur J Cardiothorac Surg 1994;8: Kazui T, Washiyama N, Muhammad BAH, et al. Extended total arch replacement for acute type A aortic dissection: experience with 70 patients. J Thorac Cardiovasc Surg 2000; 119: Leyh RG, Schmidtte C, Bartels C, Sievers HH. Valve-sparing aortic root replacement (remodeling/reimplantation) in acute type A dissection. Ann Thorac Surg 2000;70: Graeter TP, Langer F, Nikoloudakis N, Aicher D, Schafers HJ. Valve-preserving operation in acute aortic dissection type A. Ann Thorac Surg 2000;70: Guilmet D, Bachet J, Goudot B, et al. Use of biological glue in acute aortic dissection. Preliminary clinical results with a new surgical technique. J Thorac Cardiovasc Surg 1979;77: Albes JM, Krettek C, Hausen B, Rohde R, Haverich A, Borst HG. Biological properties of the gelatin-resorcinformaldehyde/glutaraldehyde adhesive. Ann Thorac Surg 1993;56: Eddy CA, Lenz S. A three month study to determine the effect of Bioglue surgical adhesive in the surgical repair of aortic dissection in sheep. Cryolife study No Cryolife Inc, Kennesaw, GA: Ergin MA, McCullough J, Galla JD, Lansman SL, Griepp RB. Radical replacement of the aortic root in acute type A dissection: indications and outcome. Eur J Cardiothorac Surg 1996;10: David TE, Feindel CM, Bos J. Repair of the aortic valve in patients with aortic insufficiency and aortic root aneurysm. J Thorac Cardiovasc Surg 1995;109: Kon ND, Cordel AR, Adair SM, Dobbins JE, Kitzman DW. Aortic root replacement with free style stentless porcine aortic root bioprosthesis. Ann Thorac Surg 1999;67: