New open stent-graft delivery system: the CLATE flexible metal graft holder
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《交互式心脏血管和胸部手术》
Department of Cardiovascular Surgery, Kyorin University, 6-20-2, Shinkawa, Mitaka-shi, 181-8611, Tokyo, Japan
Abstract
The surgical approach to the treatment of distal aortic arch aneurysms is still a matter of controversy. Median sternotomy is usually selected when the patient has the pulmonary emphysema, and the atherosclerotic change involves the ascending aorta or the aortic arch as well as the distal aortic arch. However, when the end of the aneurysm is deep and distant, distal anastomosis becomes more difficult. Left thoracotomy is another approach, but in the patients with impaired respiratory function or when dense lung adhesions to the chest wall are anticipated because of a history of inflammation, the risk of intraoperative bleeding and postoperative respiratory complications becomes a major concern. Total arch replacement by an open stent graft insertion method through a median sternotomy has been devised as a procedure that overcomes these problems. However, since no ideal device for delivering long stent grafts beyond the aneurysm is available, we developed a new delivery system, and we successfully applied it clinically in a patient with an enlarged distal aortic arch.
Key Words: Aortic aneurysm; Stent graft; Thoracic aorta
1. Introduction
The open stent graft insertion technique is now being widely used to treat distal aortic arch aneurysms. When the stent graft is short, insertion with a commercially available straight sheath is easy, but a pre-curved sheath is preferable to prevent intimal injury when landing a long stent-graft beyond the aneurysm. A new open stent-graft delivery system called the CLATE (Senko Medical Instrument Mfg, Co, Ltd, Tokyo, Japan; patent pending) has been developed for long stent-graft insertion and clinically applied.
2. Device
The CLATE delivery system consists of two parts: a metal plate and a cover. The metal plate is widely used to expose the operative field in general surgery and is referred to as a ‘spatula’. There are several small holes at regular intervals in the plate, and thread can be passed through them. Several metallic rings have been welded to the dorsal side of the plate so that the thread can be passed through the holes and guided to the caudal end-plates without twining. The end-plates also have been welded to the dorsal side of the plate. The end-plates contain small holes that allow the threads to be passed through and fixed with forceps. The ventral side of the plate has a smooth surface. The plate can be bent manually to fit the curvature of the distal arch. The curvature of the plate is maintained even when the threads are pulled caudally with great force. The cover is made of silicone. It shields the welded projections on the dorsal side of the plate to prevent injuring the intima and scratching the atheroma when pulling the plate out. The stent graft is placed on the plate and held in position by several threads passed through holes on the plate and guided to the end-plates. When the threads are drawn taut, the stent graft collapses, and becomes tightly fixed to the metal plate. When the threads are released and pulled out, the stent graft expands automatically.
Finally, the delivery system is withdrawn through the space between the expanded stent graft and aortic wall.
3. Case
A 62-year-old male was diagnosed with aortic dissection (DeBakey IIIb) in 1998 and followed up by means of computed tomography examinations twice a year. The diameter of the distal arch gradually increased, and when the maximum diameter was found to have reached 63 mm in 2004, he was admitted to our hospital for surgery. The ascending aorta had also enlarged, and the aortic arch exhibited heavy calcification and dense atheromatous change. The aneurysm extended to the mid-portion of the descending aorta (Fig. 1A–D), and even at the level of the tracheal bifurcation, the diameter of the descending aorta was 52 mm. There were multiple bullae in the lungs, and the lungs were emphysematous bilaterally. The patient's 1-s forced expiratory volume rate (FEV 1.0%) had decreased to 58.7%. For all of these reasons, it was considered better to avoid a left thoracotomy, and total arch replacement through a median sternotomy with open stent-graft insertion using the CLATE system was performed on June 15, 2004. Before making a skin incision, the CLATE system was prepared by weaving a 35-mm UBE woven graft (UBE-JUNKEN, Tokyo, Japan) onto a Z-stent (GZV 40–50; William Cook Europe, Bjaeverskov, Denmark). Under deep hypothermic circulatory arrest and retrograde cerebral perfusion, the aorta was transected just distal to the left subclavian artery. Before inserting the stent graft, another metal plate of the same size as the CLATE was bent and inserted into the distal aortic arch to verify the angle of curvature of the distal arch (Fig. 2A,B). The CLATE was then bent to the same curvature as the metal plate and inserted into the aorta, and the threads were then released and pulled out. After confirming that the stent graft was properly positioned and had expanded promptly by transesophageal echography, the CLATE was pulled out. The silicone cover is effective in preventing scraping of the aortic intima, and the smooth surface of both the cover and metal plate enabled the pull-out procedure to be performed quite smoothly. The graft was cut and fixed to the transected edge of the aorta. The length of the inserted stent graft was 16 cm. Arch replacement was then performed by the standard procedure. The duration of the operation was 6 h 50 min, and blood loss was 163 ml. Circulatory arrest time was 84 min, and aortic cross clamp time was 138 min. The postoperative course was uneventful. The patient was extubated on postoperative day 3, and he was discharged three weeks after the operation. Postoperative computed tomography showed no intimal injury, a thrombosed aneurysm, and a well landed stent graft at the level of the 8th9th thoracic vertebrae (Fig. 3). Computed tomography taken one year after the operation showed that the maximum diameter of the aneurysm had decreased to 50 mm (Fig. 4).
Fig. 1A–D. The diameter of the distal aortic arch was 63 mm. Even at the level of the tracheal bifurcation, the diameter of the descending aorta was 52 mm. The ‘landing site’ located in the mid-portion of the descending aorta, where the diameter of the aorta was 30 mm.
Fig. 2A–C. The CLATE delivery system consists of two parts: a plate and a cover. The metal plate is made from a ‘spatula’ that is widely used to expose a wide operative field for abdominal surgery. The plate has several holes and rings to thread and fix it. Several monofilament threads have been passed around the stent graft, and the threads have been passed through the holes and rings in the metal plate. Each thread is held with a Pean forceps. when the threads are pulled, the stent graft is compressed and fixed tightly to the metal plate. The backside of the plate has been covered with a silicone cover. The plate has been bent to have the same curvature as the distal aortic arch and inserted far caudally into the descending aorta.
4. Discussion
There are several ways of inserting and deploying a stent graft. The most common way is to insert a compressed stent graft in a catheter sheath into the descending aorta and then deploy the graft by holding the pushing rod and withdrawing the sheath [1,2]. However, it is sometimes difficult to insert the stent grafts into the descending aorta, because they scrape against the vessel wall. To reduce the risk of this, Miyamoto et al. devised a ‘chain-stitch bonding method’ in which a nephrostomy catheter with a balloon is used to protect the aortic wall from the graft tip [3]. This method is unique, and the results have been good, but it takes time to prepare, and when applied to patients with aortic dissection or dense atheromatous change, the flexible and unstable shape of the catheter is still capable of injuring the aortic intima. The CLATE system was developed to overcome these problems. It can be prepared in a short time. It takes no more than five minutes to set up the entire system. The metal plate can be bent manually to fit the aortic curve, and the plate is covered with silicone and has a dull edge and smooth surface to protect against peripheral embolism and intimal injury that may cause aortic dissection. Thus, it enables safe, deep insertion of the stent graft. If the stent graft is improperly positioned, it can be moved to a better site by pulling up the threads again and moving the plate.
In the case presented, the distal landing zone was a sick portion of the aorta. However, because the dissection was chronic and the false lumen was small and fully thrombosed, it was considered safe to land the stent graft there. Although the stent graft could have been inserted more deeply into the aorta, we avoided doing so to prevent increasing the risk of paraplegia.
As of March 2006, our new system has been used for total arch replacement with open stent graft insertion to treat extensive thoracic aortic aneurysms in four cases, including our own case, and there have been no intra- or postoperative device-related complications. Extensive deployment of the stent graft may be associated with an increased risk of paraplegia. Further careful investigation is required.
5. Conclusion
Our new open-stent delivery system has features that may improve the safety of open stent graft insertion to treat distal aortic arch aneurysms that extend to the mid-portion of the descending aorta. Careful prospective evaluation is needed to confirm its relative safety and efficacy.
References
Kato M, Kaneko M, Kuratani T, Horiguchi K, Ikushima H, Ohnishi K. New operative method for distal aortic arch aneurysm: combined cervical branch bypass and endovascular stent-graft implantation. J Thorac Cardiovasc Surg 1999; 117:832–834.
Sueda T, Watari M, Orihashi K, Shikata H, Matsuura Y. Endovascular stent-grafting via the aortic arch for chronic aortic dissection combined with coronary artery bypass grafting. J Thorac Cardiovasc Surg 1999; 117:825–827.
Miyamoto S, Hadama T, Anai H, Sako H, Iwata E, Hamamoto H. An easy, safe, and sure way of open stent grafting: Chain-Stitch bonding with a balloon catheter. Surg Today 2002; 32:568–570.(Hiroshi Kubota, Hidehito )
Abstract
The surgical approach to the treatment of distal aortic arch aneurysms is still a matter of controversy. Median sternotomy is usually selected when the patient has the pulmonary emphysema, and the atherosclerotic change involves the ascending aorta or the aortic arch as well as the distal aortic arch. However, when the end of the aneurysm is deep and distant, distal anastomosis becomes more difficult. Left thoracotomy is another approach, but in the patients with impaired respiratory function or when dense lung adhesions to the chest wall are anticipated because of a history of inflammation, the risk of intraoperative bleeding and postoperative respiratory complications becomes a major concern. Total arch replacement by an open stent graft insertion method through a median sternotomy has been devised as a procedure that overcomes these problems. However, since no ideal device for delivering long stent grafts beyond the aneurysm is available, we developed a new delivery system, and we successfully applied it clinically in a patient with an enlarged distal aortic arch.
Key Words: Aortic aneurysm; Stent graft; Thoracic aorta
1. Introduction
The open stent graft insertion technique is now being widely used to treat distal aortic arch aneurysms. When the stent graft is short, insertion with a commercially available straight sheath is easy, but a pre-curved sheath is preferable to prevent intimal injury when landing a long stent-graft beyond the aneurysm. A new open stent-graft delivery system called the CLATE (Senko Medical Instrument Mfg, Co, Ltd, Tokyo, Japan; patent pending) has been developed for long stent-graft insertion and clinically applied.
2. Device
The CLATE delivery system consists of two parts: a metal plate and a cover. The metal plate is widely used to expose the operative field in general surgery and is referred to as a ‘spatula’. There are several small holes at regular intervals in the plate, and thread can be passed through them. Several metallic rings have been welded to the dorsal side of the plate so that the thread can be passed through the holes and guided to the caudal end-plates without twining. The end-plates also have been welded to the dorsal side of the plate. The end-plates contain small holes that allow the threads to be passed through and fixed with forceps. The ventral side of the plate has a smooth surface. The plate can be bent manually to fit the curvature of the distal arch. The curvature of the plate is maintained even when the threads are pulled caudally with great force. The cover is made of silicone. It shields the welded projections on the dorsal side of the plate to prevent injuring the intima and scratching the atheroma when pulling the plate out. The stent graft is placed on the plate and held in position by several threads passed through holes on the plate and guided to the end-plates. When the threads are drawn taut, the stent graft collapses, and becomes tightly fixed to the metal plate. When the threads are released and pulled out, the stent graft expands automatically.
Finally, the delivery system is withdrawn through the space between the expanded stent graft and aortic wall.
3. Case
A 62-year-old male was diagnosed with aortic dissection (DeBakey IIIb) in 1998 and followed up by means of computed tomography examinations twice a year. The diameter of the distal arch gradually increased, and when the maximum diameter was found to have reached 63 mm in 2004, he was admitted to our hospital for surgery. The ascending aorta had also enlarged, and the aortic arch exhibited heavy calcification and dense atheromatous change. The aneurysm extended to the mid-portion of the descending aorta (Fig. 1A–D), and even at the level of the tracheal bifurcation, the diameter of the descending aorta was 52 mm. There were multiple bullae in the lungs, and the lungs were emphysematous bilaterally. The patient's 1-s forced expiratory volume rate (FEV 1.0%) had decreased to 58.7%. For all of these reasons, it was considered better to avoid a left thoracotomy, and total arch replacement through a median sternotomy with open stent-graft insertion using the CLATE system was performed on June 15, 2004. Before making a skin incision, the CLATE system was prepared by weaving a 35-mm UBE woven graft (UBE-JUNKEN, Tokyo, Japan) onto a Z-stent (GZV 40–50; William Cook Europe, Bjaeverskov, Denmark). Under deep hypothermic circulatory arrest and retrograde cerebral perfusion, the aorta was transected just distal to the left subclavian artery. Before inserting the stent graft, another metal plate of the same size as the CLATE was bent and inserted into the distal aortic arch to verify the angle of curvature of the distal arch (Fig. 2A,B). The CLATE was then bent to the same curvature as the metal plate and inserted into the aorta, and the threads were then released and pulled out. After confirming that the stent graft was properly positioned and had expanded promptly by transesophageal echography, the CLATE was pulled out. The silicone cover is effective in preventing scraping of the aortic intima, and the smooth surface of both the cover and metal plate enabled the pull-out procedure to be performed quite smoothly. The graft was cut and fixed to the transected edge of the aorta. The length of the inserted stent graft was 16 cm. Arch replacement was then performed by the standard procedure. The duration of the operation was 6 h 50 min, and blood loss was 163 ml. Circulatory arrest time was 84 min, and aortic cross clamp time was 138 min. The postoperative course was uneventful. The patient was extubated on postoperative day 3, and he was discharged three weeks after the operation. Postoperative computed tomography showed no intimal injury, a thrombosed aneurysm, and a well landed stent graft at the level of the 8th9th thoracic vertebrae (Fig. 3). Computed tomography taken one year after the operation showed that the maximum diameter of the aneurysm had decreased to 50 mm (Fig. 4).
Fig. 1A–D. The diameter of the distal aortic arch was 63 mm. Even at the level of the tracheal bifurcation, the diameter of the descending aorta was 52 mm. The ‘landing site’ located in the mid-portion of the descending aorta, where the diameter of the aorta was 30 mm.
Fig. 2A–C. The CLATE delivery system consists of two parts: a plate and a cover. The metal plate is made from a ‘spatula’ that is widely used to expose a wide operative field for abdominal surgery. The plate has several holes and rings to thread and fix it. Several monofilament threads have been passed around the stent graft, and the threads have been passed through the holes and rings in the metal plate. Each thread is held with a Pean forceps. when the threads are pulled, the stent graft is compressed and fixed tightly to the metal plate. The backside of the plate has been covered with a silicone cover. The plate has been bent to have the same curvature as the distal aortic arch and inserted far caudally into the descending aorta.
4. Discussion
There are several ways of inserting and deploying a stent graft. The most common way is to insert a compressed stent graft in a catheter sheath into the descending aorta and then deploy the graft by holding the pushing rod and withdrawing the sheath [1,2]. However, it is sometimes difficult to insert the stent grafts into the descending aorta, because they scrape against the vessel wall. To reduce the risk of this, Miyamoto et al. devised a ‘chain-stitch bonding method’ in which a nephrostomy catheter with a balloon is used to protect the aortic wall from the graft tip [3]. This method is unique, and the results have been good, but it takes time to prepare, and when applied to patients with aortic dissection or dense atheromatous change, the flexible and unstable shape of the catheter is still capable of injuring the aortic intima. The CLATE system was developed to overcome these problems. It can be prepared in a short time. It takes no more than five minutes to set up the entire system. The metal plate can be bent manually to fit the aortic curve, and the plate is covered with silicone and has a dull edge and smooth surface to protect against peripheral embolism and intimal injury that may cause aortic dissection. Thus, it enables safe, deep insertion of the stent graft. If the stent graft is improperly positioned, it can be moved to a better site by pulling up the threads again and moving the plate.
In the case presented, the distal landing zone was a sick portion of the aorta. However, because the dissection was chronic and the false lumen was small and fully thrombosed, it was considered safe to land the stent graft there. Although the stent graft could have been inserted more deeply into the aorta, we avoided doing so to prevent increasing the risk of paraplegia.
As of March 2006, our new system has been used for total arch replacement with open stent graft insertion to treat extensive thoracic aortic aneurysms in four cases, including our own case, and there have been no intra- or postoperative device-related complications. Extensive deployment of the stent graft may be associated with an increased risk of paraplegia. Further careful investigation is required.
5. Conclusion
Our new open-stent delivery system has features that may improve the safety of open stent graft insertion to treat distal aortic arch aneurysms that extend to the mid-portion of the descending aorta. Careful prospective evaluation is needed to confirm its relative safety and efficacy.
References
Kato M, Kaneko M, Kuratani T, Horiguchi K, Ikushima H, Ohnishi K. New operative method for distal aortic arch aneurysm: combined cervical branch bypass and endovascular stent-graft implantation. J Thorac Cardiovasc Surg 1999; 117:832–834.
Sueda T, Watari M, Orihashi K, Shikata H, Matsuura Y. Endovascular stent-grafting via the aortic arch for chronic aortic dissection combined with coronary artery bypass grafting. J Thorac Cardiovasc Surg 1999; 117:825–827.
Miyamoto S, Hadama T, Anai H, Sako H, Iwata E, Hamamoto H. An easy, safe, and sure way of open stent grafting: Chain-Stitch bonding with a balloon catheter. Surg Today 2002; 32:568–570.(Hiroshi Kubota, Hidehito )