The Neuroradiology Journal 20: 327-330, 2007
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Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience PENG YA, XUAN JING-GANG, YANG YI-LIN, WANG SUI-NUAN Department of Neurosurgery, The First Hospital; Chang Zhou City, Jiang Su Province, China
Key words: hydrocoil, aneurysms, embolization
SUMMARY – The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA, USA) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The HES may reduce recurrences of aneurysms by allowing for increased packing density compared with platinum coils. We report our initial experience with the HES in the treatment of 31 patients with acute ruptured cerebral aneurysms. The HES is another safe and effective material for aneurysms embolization, which provided substantially improved volumetric packing of the aneurysm lumen.
Introduction Despite rapid advances in endovascular devices and technology, a principal disadvantage of endovascular therapy of cerebral aneurysms with coils compared with surgical clipping is aneurysm recurrence 1,2. Some cases with a recanalized aneurysm are at risk of delayed aneurysm rupture and may require further treatment. This recurrence following endovascular therapy is likely related to the density of packing of coils into the lumen 3-5. The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA, USA) is designed with an expansile hydrogel that should theoretically fill more of the aneurysm lumen than standard platinum coils 6. We report our experience with the HES in 31 cases of acute ruptured cerebral aneurysms. Material and Methods From May 2005 to July 2006, 31 aneurysms in 31 patients were treated using the HES. Of the 31 patients, 15 were men and 16 were women. The mean age of the patients was 56+11.2 years (range, 31-74 years). All patients presented with SAH, Hunt and Hess grades were I in five cases, II in 12, III in ten and IV
in four. There were 14 anterior communicating aneurysms, nine posterior communicating aneurysms, five middle cerebral artery bifurcation aneurysms, one basilar tip aneurysm and two cavernous internal carotid artery (ICA) aneurysms. The mean width of the aneurysm dome was 4.5+2.1 mm (range, 2.8-10.2 mm), its mean height was 6.5+2.6 mm (range, 3.6-12.8 mm), five aneurysms had a neck of more than 4 mm. The aneurysms were treated in the standard manner as we used standard coils. First a standard platinum framing coil (MicroVention, Aliso Viejo, CA, USA) was deposited in the aneurysm. HES coils were then deposited to fill most of the aneurysm volume. Finally, the remainder of the aneurysm was then filled with small, soft platinum coils (figure 1). Four cases of wide-necked ICA aneurysms required Neuroform stent placement, two microcatheter techniques were used for one case of wide-necked basilar tip aneurysm. The coil packing density was expressed using the following formula: packing density = (coil volume/ aneurysm volume) ×100%. The HES provided packing of the aneurysm lumen 56-76%, mean parking density was 68%. After embolization there were three cases with cerebral ventricular hemorrhage who received external ventricular drainage. 327
Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience
A
Peng Ya
B C
Figure 1 A-C Case 1, a 36-year-old woman with SAH. A) Left internal carotid angiogram shows an anterior communicating artery aneurysm with vasospasm. B) Angiogram obtained immediately after embolization shows compact occlusion of the aneurysmal sac. C) Angiogram obtained six months after embolization shows no recanalization.
Results All aneurysms were successfully embolized. Immediate postembolization angiography showed no residual contrast filling in 27 patients and some residual contrast filling in four patents. No clinical complications occurred in this group. The duration of the clinical follow-up ranged six to 12 months after the treatment. No new bleeding occurred during the following period. 328
Follow-up angiography was performed in six patients after six months. No coil compaction or partial recanalization were found. Discussion HydroCoils are new devices that consist of carrier platinum coils coupled to an expandable hydrogel material that results in delayed progressive expansion of the coil once it comes into
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contact with a substance, such as blood, with a pH of 7.4. The expansion is expected to begin five minutes after exposure and is completed by 20 minutes. Hence the system is not similar to bare coils alone. In our experience, there are some technical notes. The first coil we select is always a bare platinum framing coil. It is important to frame a satisfactory basket in the lumen of the aneurysm. Then we can easily follow by packing HydroCoils. When the interim angiography shows there is almost no residual filling in the sac, we should wait for 20 minutes until the HES coils expand completely. Repetitive angiography will determine if another coil is needed. We advocate using a small, soft standard platinum coil as the “finishing” coil because the HydroCoil is stiffer than a bare coil and therefore it is more difficult to adjust as a final coil. As we know, the HydroCoil expands as much as nine times its prehydrated volume. Does this expansion lead to the dangerous changes in the intra-aneurysmal fluid pressure which may make the aneurysm rupture? A study demonstrated that even packing the aneurysm with HydroCoils at a density up to 93% did not increase the intra-aneurysmal fluid pressure 7. The HydroCoil for Embolic Aneurysm Occlusion (HEAL) trial reported that periprocedural thromboembolic events occurred in 8.1% and neurologic deficits related to thromboemboli occurred in 2.1% of aneurysms treated, intraprocedural aneurysm perforations occurred in 2.8% of previously ruptured aneurysms, and in 0% of previously unruptured aneurysms. So the initial occlusion success and complication rate when HES is used to treat cerebral aneurysms is not significantly different from that of platinum coils 8. Many studies have shown a significant correlation between packing density and the stability of embolized aneurysms 3-5. Aneurysms
The Neuroradiology Journal 20: 327-330, 2007
treated with coil packing are only partially filled with coils, with most of the intraluminal volume being filled initially with thrombus 9. Indeed, low aneurysm coil packing density is reasonably associated with an increased risk of aneurysm recurrence. The expansile hydrogel on the HES displaces thrombus from the aneurysm lumen, resulting in a better packing density. An animal trial demonstrated volumetric occlusion for HydroCoil (76%) was significantly greater than both platinum coils (31%) and Matrix (23%). Angiographic durability was significantly increased in the HydroCoil group compared with Matrix. In the rabbit model, the use of HydroCoils resulted in improved long-term occlusion rates compared with Matrix and platinum coils 12. Cloft also reported the HydroCoil provided improved packing of the aneurysm lumen relative to standard platinum coils (72% vs. 32%) 13. An additional apparent advantage of HydroCoils is that they may cause advanced healing and endothelialization at the aneurysm neck, the evidence was that on angiographic six months follow-up after treatment, a clearly defined radiolucent separation of the coils from the parent artery was noted in many of the aneurysms 10,11 . This is a limited study of initial experience at a single center. Although the aneurysm packing density with HES is improved, the effectiveness of hydrogel in preventing aneurysm recurrence remains to be proved by longer follow-up. Our initial experience demonstrates that the HES allows substantially improved volumetric packing of the aneurysm lumen. Short-term follow-up in some cases demonstrates that no coil compaction or partial recanalization are found. Further study is required to determine whether the HES can effectively prevent aneurysm recurrence.
References 1 International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002; 360:1267-1274. 2 Cognard C, Weill A, Spelle L et Al: Long-term angiographic follow-up of 169 intracranial berry aneurysms occluded with detachable coils. Radiology 212: 348-356, 1999. 3 Kawanabe Y, Sadato A, Taki W et Al: Endovascular occlusion of intracranial aneurysms with Guglielmi detach-
able coils: correlation between coil packing density and coil compaction. Acta Neurochir 143: 451-455, 2001. 4 Tamatani S, Ito Y, Abe H et Al: Evaluation of the stability of aneurysms after embolization using detachable coils: correlation between stability of aneurysms and embolized volume of aneurysms. Am J Neuroradiol 23: 762-767, 2002. 5 Uchiyama N, Kida S, Nomura M et Al: Significance of volume embolization ratio as a predictor of recanalization on endovascular treatment of cerebral aneurysms treated with Guglielmi Detachable Coils. Interventional Neuroradiology 6: 59-63, 2000.
329
Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience
6 Kallmes DF, Fujiwara NH: New expandable hydrogelplatinum coil hybrid device for aneurysm embolization. AJNR Am J Neuroradiol 23: 1580-1588, 2002. 7 Canton G, Levy DI, Lasheras JC: Changes in the intraaneurysmal pressure due to HydroCoil embolization. Am J Neuroradiol 26: 904-907, 2005. 8 Cloft HJ: HydroCoil for Endovascular Aneurysm Occlusion (HEAL) study: periprocedural results. Am J Neuroradiol 27: 289-292, 2006. 9 Gruber A, Killer M, Bavinzski G et Al: Clinical and angiographic results of endosaccular coiling treatment of giant and very large intracranial aneurysms: a 7-year, single-center experience. Neurosurgery 45: 793-803, 1999. 10 Yoshino Y, Niimi Y, Song JK et Al: Endovascular treatment of intracranial aneurysms: comparative evaluation in a terminal bifurcation canine aneurysm model. J Neurosurg 101: 996-1003, 2004. 11 Arthur AS, Wilson SA, Dixit S et Al: Hydrogel-coated coils for the treatment of cerebral aneurysms: preliminary results. Neurosurg Focus 15: E1, 2005. 12 Ding YH, Dai D, Lewis DA et Al: Angiographic and histologic analysis of experimental aneurysms embol-
330
Peng Ya
ized with platinum coils, Matrix, and HydroCoil. Am J Neuroradiol 26: 1757-63, 2005. 13 Cloft HJ, Kallmes DF: Aneurysm packing with HydroCoil Embolic System versus platinum coils: initial clinical experience. Am J Neuroradiol 25: 60-2, 2004.
Peng Ya, MD Department of Neurosurgery The First Hospital 185 Juqian Street Chang Zhou City JiangSu Province 213003 CHINA Tel.: 0865196180037 E-mail: [email protected]
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Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience PENG YA, XUAN JING-GANG, YANG YI-LIN, WANG SUI-NUAN Department of Neurosurgery, The First Hospital; Chang Zhou City, Jiang Su Province, China
Key words: hydrocoil, aneurysms, embolization
SUMMARY – The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA, USA) was developed to improve the efficacy of endovascular treatment of cerebral aneurysms. The HES may reduce recurrences of aneurysms by allowing for increased packing density compared with platinum coils. We report our initial experience with the HES in the treatment of 31 patients with acute ruptured cerebral aneurysms. The HES is another safe and effective material for aneurysms embolization, which provided substantially improved volumetric packing of the aneurysm lumen.
Introduction Despite rapid advances in endovascular devices and technology, a principal disadvantage of endovascular therapy of cerebral aneurysms with coils compared with surgical clipping is aneurysm recurrence 1,2. Some cases with a recanalized aneurysm are at risk of delayed aneurysm rupture and may require further treatment. This recurrence following endovascular therapy is likely related to the density of packing of coils into the lumen 3-5. The HydroCoil Embolic System (HES; MicroVention, Aliso Viejo, CA, USA) is designed with an expansile hydrogel that should theoretically fill more of the aneurysm lumen than standard platinum coils 6. We report our experience with the HES in 31 cases of acute ruptured cerebral aneurysms. Material and Methods From May 2005 to July 2006, 31 aneurysms in 31 patients were treated using the HES. Of the 31 patients, 15 were men and 16 were women. The mean age of the patients was 56+11.2 years (range, 31-74 years). All patients presented with SAH, Hunt and Hess grades were I in five cases, II in 12, III in ten and IV
in four. There were 14 anterior communicating aneurysms, nine posterior communicating aneurysms, five middle cerebral artery bifurcation aneurysms, one basilar tip aneurysm and two cavernous internal carotid artery (ICA) aneurysms. The mean width of the aneurysm dome was 4.5+2.1 mm (range, 2.8-10.2 mm), its mean height was 6.5+2.6 mm (range, 3.6-12.8 mm), five aneurysms had a neck of more than 4 mm. The aneurysms were treated in the standard manner as we used standard coils. First a standard platinum framing coil (MicroVention, Aliso Viejo, CA, USA) was deposited in the aneurysm. HES coils were then deposited to fill most of the aneurysm volume. Finally, the remainder of the aneurysm was then filled with small, soft platinum coils (figure 1). Four cases of wide-necked ICA aneurysms required Neuroform stent placement, two microcatheter techniques were used for one case of wide-necked basilar tip aneurysm. The coil packing density was expressed using the following formula: packing density = (coil volume/ aneurysm volume) ×100%. The HES provided packing of the aneurysm lumen 56-76%, mean parking density was 68%. After embolization there were three cases with cerebral ventricular hemorrhage who received external ventricular drainage. 327
Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience
A
Peng Ya
B C
Figure 1 A-C Case 1, a 36-year-old woman with SAH. A) Left internal carotid angiogram shows an anterior communicating artery aneurysm with vasospasm. B) Angiogram obtained immediately after embolization shows compact occlusion of the aneurysmal sac. C) Angiogram obtained six months after embolization shows no recanalization.
Results All aneurysms were successfully embolized. Immediate postembolization angiography showed no residual contrast filling in 27 patients and some residual contrast filling in four patents. No clinical complications occurred in this group. The duration of the clinical follow-up ranged six to 12 months after the treatment. No new bleeding occurred during the following period. 328
Follow-up angiography was performed in six patients after six months. No coil compaction or partial recanalization were found. Discussion HydroCoils are new devices that consist of carrier platinum coils coupled to an expandable hydrogel material that results in delayed progressive expansion of the coil once it comes into
www. centauro. it
contact with a substance, such as blood, with a pH of 7.4. The expansion is expected to begin five minutes after exposure and is completed by 20 minutes. Hence the system is not similar to bare coils alone. In our experience, there are some technical notes. The first coil we select is always a bare platinum framing coil. It is important to frame a satisfactory basket in the lumen of the aneurysm. Then we can easily follow by packing HydroCoils. When the interim angiography shows there is almost no residual filling in the sac, we should wait for 20 minutes until the HES coils expand completely. Repetitive angiography will determine if another coil is needed. We advocate using a small, soft standard platinum coil as the “finishing” coil because the HydroCoil is stiffer than a bare coil and therefore it is more difficult to adjust as a final coil. As we know, the HydroCoil expands as much as nine times its prehydrated volume. Does this expansion lead to the dangerous changes in the intra-aneurysmal fluid pressure which may make the aneurysm rupture? A study demonstrated that even packing the aneurysm with HydroCoils at a density up to 93% did not increase the intra-aneurysmal fluid pressure 7. The HydroCoil for Embolic Aneurysm Occlusion (HEAL) trial reported that periprocedural thromboembolic events occurred in 8.1% and neurologic deficits related to thromboemboli occurred in 2.1% of aneurysms treated, intraprocedural aneurysm perforations occurred in 2.8% of previously ruptured aneurysms, and in 0% of previously unruptured aneurysms. So the initial occlusion success and complication rate when HES is used to treat cerebral aneurysms is not significantly different from that of platinum coils 8. Many studies have shown a significant correlation between packing density and the stability of embolized aneurysms 3-5. Aneurysms
The Neuroradiology Journal 20: 327-330, 2007
treated with coil packing are only partially filled with coils, with most of the intraluminal volume being filled initially with thrombus 9. Indeed, low aneurysm coil packing density is reasonably associated with an increased risk of aneurysm recurrence. The expansile hydrogel on the HES displaces thrombus from the aneurysm lumen, resulting in a better packing density. An animal trial demonstrated volumetric occlusion for HydroCoil (76%) was significantly greater than both platinum coils (31%) and Matrix (23%). Angiographic durability was significantly increased in the HydroCoil group compared with Matrix. In the rabbit model, the use of HydroCoils resulted in improved long-term occlusion rates compared with Matrix and platinum coils 12. Cloft also reported the HydroCoil provided improved packing of the aneurysm lumen relative to standard platinum coils (72% vs. 32%) 13. An additional apparent advantage of HydroCoils is that they may cause advanced healing and endothelialization at the aneurysm neck, the evidence was that on angiographic six months follow-up after treatment, a clearly defined radiolucent separation of the coils from the parent artery was noted in many of the aneurysms 10,11 . This is a limited study of initial experience at a single center. Although the aneurysm packing density with HES is improved, the effectiveness of hydrogel in preventing aneurysm recurrence remains to be proved by longer follow-up. Our initial experience demonstrates that the HES allows substantially improved volumetric packing of the aneurysm lumen. Short-term follow-up in some cases demonstrates that no coil compaction or partial recanalization are found. Further study is required to determine whether the HES can effectively prevent aneurysm recurrence.
References 1 International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 2002; 360:1267-1274. 2 Cognard C, Weill A, Spelle L et Al: Long-term angiographic follow-up of 169 intracranial berry aneurysms occluded with detachable coils. Radiology 212: 348-356, 1999. 3 Kawanabe Y, Sadato A, Taki W et Al: Endovascular occlusion of intracranial aneurysms with Guglielmi detach-
able coils: correlation between coil packing density and coil compaction. Acta Neurochir 143: 451-455, 2001. 4 Tamatani S, Ito Y, Abe H et Al: Evaluation of the stability of aneurysms after embolization using detachable coils: correlation between stability of aneurysms and embolized volume of aneurysms. Am J Neuroradiol 23: 762-767, 2002. 5 Uchiyama N, Kida S, Nomura M et Al: Significance of volume embolization ratio as a predictor of recanalization on endovascular treatment of cerebral aneurysms treated with Guglielmi Detachable Coils. Interventional Neuroradiology 6: 59-63, 2000.
329
Acute Ruptured Intracranial Aneurysm Packing with HydroCoil Embolic System: Initial Clinical Experience
6 Kallmes DF, Fujiwara NH: New expandable hydrogelplatinum coil hybrid device for aneurysm embolization. AJNR Am J Neuroradiol 23: 1580-1588, 2002. 7 Canton G, Levy DI, Lasheras JC: Changes in the intraaneurysmal pressure due to HydroCoil embolization. Am J Neuroradiol 26: 904-907, 2005. 8 Cloft HJ: HydroCoil for Endovascular Aneurysm Occlusion (HEAL) study: periprocedural results. Am J Neuroradiol 27: 289-292, 2006. 9 Gruber A, Killer M, Bavinzski G et Al: Clinical and angiographic results of endosaccular coiling treatment of giant and very large intracranial aneurysms: a 7-year, single-center experience. Neurosurgery 45: 793-803, 1999. 10 Yoshino Y, Niimi Y, Song JK et Al: Endovascular treatment of intracranial aneurysms: comparative evaluation in a terminal bifurcation canine aneurysm model. J Neurosurg 101: 996-1003, 2004. 11 Arthur AS, Wilson SA, Dixit S et Al: Hydrogel-coated coils for the treatment of cerebral aneurysms: preliminary results. Neurosurg Focus 15: E1, 2005. 12 Ding YH, Dai D, Lewis DA et Al: Angiographic and histologic analysis of experimental aneurysms embol-
330
Peng Ya
ized with platinum coils, Matrix, and HydroCoil. Am J Neuroradiol 26: 1757-63, 2005. 13 Cloft HJ, Kallmes DF: Aneurysm packing with HydroCoil Embolic System versus platinum coils: initial clinical experience. Am J Neuroradiol 25: 60-2, 2004.
Peng Ya, MD Department of Neurosurgery The First Hospital 185 Juqian Street Chang Zhou City JiangSu Province 213003 CHINA Tel.: 0865196180037 E-mail: [email protected]
