1. Optimal Graft Diameter and Location Reduces Postoperative Complications Following Total Arch Replacement with a Long Elephant Trunk K. Taniguchi K.Toda T. Funatsu H. Hondoh K. Sakakibara Cardiovascular Surgery, Osaka Rosai Hospital, Sakai, Japan

2. ・ The fate of the descending aorta around the distal end of the ET remains unclear. Background (Kuki S, et.al., Circulation 2002;106:I253-258) (Taniguchi K, et.al., Ann Thorac Surg 2007;84:1729-34) (Toda K, et.al., J Thorac Cardiovasc Surg 2007;134:47-52) (Svensson LG, et.al. Ann Thorac Surg 2001;71:1050-2) (Svensson LG, et.al. Ann Thorac Surg 2002;74:S1803-5) ・ Serious complications, such as paraplegia and peripheral embolic complications caused by flapping action of the elephant trunk, remain concerns after total arch replacement with an ET. ・ Total arch replacement using an elephant trunk (ET) is a less invasive and easy-to-perform technique for arch aneurysm repair with satisfactory early and midterm results. ・ Moreover, when retrograde flow from the distal end of the ET into the peri-graft space around the ET remains, further dilation of the descending aorta or the rupture of the aneurysmal aorta may occur. (Crawford ES, et.al. Ann Surg 1990;211:521-37)

3. Hypothesis We hypothesized that an optimal location and graft diameter would allow for tight positioning in the descending aorta to prevent retrograde flow perfusion and flapping action by the graft, leading to reduced peripheral embolic complications, to achieve complete thrombosis and minimal dilation of the descending aorta around the elephant trunk after total arch replacement. Objectives We addressed the following specific questions: 1) Is the location of the end of the graft associated with increased risk of spinal cord injury or endleak? 2) Would a graft undersized by 10-20% of the descending aortic diameter used for the ET reduce postoperative peripheral embolic events and paraplegia? 3) Would a graft undersized by 10-20% of the descending aortic diameter used for the ET prevent retrograde flow and dilation of the descending aorta around the ET?

4. From July 1999, 65 consecutive patients with an arch aneurysm underwent total arch replacement with a long elephant trunk (ET) anastomosed at the base of the innominate artery. Des.AoD Patients: ΔL 1)ΔL: Length from the origin of the descending aorta at the lesser curvature of aortic arch to the distal end of the ET. 2)Des.AoD: Diameter of the descending aorta at, 2 cm above, and 2 cm below the distal end of the ET. 3) ΔD: Distance between the diameter of the descending aorta and the ET at and 1, 2 and 3 cm above the distal end of the ET. Evaluations were performed postoperatively with CT at 1 week, 1 month, 1 year, and every year thereafter. Measurements: Methods (1)

5. Methods (2) 1)Operative outcome 2)Location of the distal end of the ET (thoracic vertebral level and ΔL), and spinal cord injury or endleak 3)Fate of the descending aorta around the distal end of the ET ・ Endleak in the late phase ・ Further dilation of Des.AoD ・ Further dilation of ΔD Graft diameter and length of the elephant trunk: Graft diameter was undersized by 10-20% (range 18-28 mm) of the distal aortic diameter. Length of the elephant trunk was determined preoperatively by measuring the aorta from the base of the innominate artery to the end of the aneurysm using CT, to locate the distal end at the 6th to 8th thoracic vertebral level. Evaluations:

6. Operative technique (1) CPB is established via bicaval and right axillary artery cannulae, and the ascending aorta is incised. While cooling the patient, a proximal anastomosis is performed. A long elephant trunk is inserted into the descending aorta aided by a catching catheter under an open distal condition. 2-0 Tevdek suture

7. Operative technique (2) A distal anastomosis is then performed at the base of the innominate artery between the proximal graft and the distal aorta, incorporating the ET tube graft. The arch vessels are individually reconstructed while re-warming the patient.

8. Results (1): Mortality and morbidity ・ Operative deaths: None ・ Hospital mortalities: 3 (5%) 1 mediastinitis, 1 pneumoniae, 1 graft infection ・ New stroke: None ・ Recurrent nerve palsy, phrenic nerve palsy: None ・ Paraplegia: 1 (2%), Paraparesis: 1 (2%), Transient paraplegia: 1 (2%) ・ Retrograde flow into the peri-graft space (endleak): 7 (11%) 6: underwent second stage operation 1: being followed ・ Endleak in the late phase: None ・ Aneurysmal rupture: None ・ Peripheral embolic events: None

9. Result (2) : Location of distal end of graft 10 9 8 7 6 5 4 ΔL (cm) 2 4 6 8 10 12 14 16 18 paraplegia paraparesis transient paraplegia Th level endleak 21 1 1 1 1 1 11 Endleak (+) ( n = 7 ) Endleak (-) ( n = 58 ) Th6.9 ± 1.67.5 ± 1.2P=0.1852 ΔL (cm)4.8 ± 2.18.4 ± 3.5P=0.0183 Extensive deployment of the graft was associated with an increased risk of spinal cord injury and short deployment of the graft was associated with endleak. ΔL varied, even when the distal end of the graft was positioned at the same thoracic vertebral level. (Th : thoracic vertebral level of distal end of graft. )

10. Result (3) : Des.AoD 1W 1M 1Y 2Y 3Y 4Y 34 32 30 28 26 24 22 (mm) 34 32 30 28 26 24 22 (mm) 34 32 30 28 26 24 22 (mm) 2 cm below distal end of graft At distal end of graft 2 cm above distal end of graft [W: week(s), M: month(s), Y: year(s)] The diameter of the descending aorta at each segment did not show dilatation for at least 4 years after total arch replacement.

11. Result (4): ΔD 12 10 8 6 4 2 0 (mm) 12 10 8 6 4 2 0 (mm) 12 10 8 6 4 2 0 (mm) 12 10 8 6 4 2 0 (mm) 1W 1M 1Y 2Y 3Y 4Y ΔD 3 cm above distal end of graft ΔD 2 cm above distal end of graft ΔD 1 cm above distal end of graft ΔD at distal end of graft [W: week(s), M: month(s), Y: year(s)] ΔD at each segment was not significantly different, though it gradually and progressively decreased in size. This phenomenon suggests that an undersized graft would continue to effectively prevent retrograde flow into the aneurysm for a long period.

12. Summary ・ The descending aorta around the ET showed complete thrombosis between the graft and descending aorta without peripheral embolic events or paraplegia in most patients after total arch replacement. ・ Although endleak remained in the early phase in 7 patients (11%), it was successfully prevented without dilation of the descending aorta around the graft for at least 4 years in the remaining 58 patients (89%). ・ Use of a graft undersized by 10-20% of the descending aortic diameter for the ET resulted in the following: ・ Extensive deployment of the graft was associated with increased risk of spinal cord injury, while short deployment of the graft was associated with endleak.

13. Optimal graft diameter and location minimized postoperative complications, with complete thrombosis and without dilation of the descending aorta around the long elephant trunk after total arch replacement in most of the patients. Conclusion