New embolization technique for intracranial vascular disease with the assistance of an Apollo microcatheter

Abstract

It is difficult to access small and remote intracranial vascular lesions when using routine coil-delivery microcatheters. A thin Apollo microcatheter can access these vascular lesions. The Apollo microcatheter is intended to reduce the risk of catheter entrapment during the deployment of Onyx due to the detachable tip; furthermore, the Apollo microcatheter with a 3 cm detachable tip has 2 markers. X-ray imaging revealed that the marker on the push lever of the coil matched the proximal marker on the Apollo microcatheter. Therefore, it can replace routine coil-delivery microcatheters to deliver certain coils and then cast Onyx following coiling. The technique has rarely been reported. Patient 1 was a 59-year-old male with a ruptured aneurysm at the branch of posterior cerebral artery. The aneurysm was coiled with a Jasper ®SS-10 coil via an Apollo microcatheter with a 3 cm detachable tip. Then, Onyx-18 was used to obliterate the aneurysm. The patient recovered well after the procedure. Patient 2 was a 51-year-old male with a brain arteriovenous malformation (BAVM). There was a fistulous structure in the nidus. The Apollo microcatheter with a 3 cm detachable tip was used to reach and coil the fistulous structure with a Jasper ®SS-10 coil. Then, Onyx-18 was used to partially embolize the BAVM. The patient recovered well after the procedure. Therefore, the use of an Apollo microcatheter with a 3 cm detachable tip to deliver both coils and Onyx represents a new approach for treating intracranial vascular diseases when routine coil-delivery microcatheters cannot reach the lesions.

Introduction

Intracranial peripheral aneurysms beyond the circle of Willis and intranidal fistulous structures in brain arteriovenous malformations (BAVMs) are often in very remote locations [1,2]. Routine coil-delivery microcatheters with 2 markers of 3 cm distance, such as Echelon-10 (Medtronic, Irvine, CA, USA) and SL-10 (Stryker Neurovascular, Fremont, CA, USA), may be too short to access these structures because they are 150 cm in length. In addition, these coil-delivery microcatheters were too thick to catheterize the thin parent artery of the aneurysm or the feeding artery of the BAVM because of the 1.7F or 1.8F distal tips.

In this study, long and small Marathon and Apollo microcatheters (Medtronic, Minneapolis, MI, USA) were used to overcome the drawbacks of routine coil-delivery microcatheters. The microcatheters were 165 cm long with a thin 1.5F distal tip to enable access to remote lesions (Fig. 1) [3]. Certain types of coils can be delivered via Marathon and Apollo microcatheters, and after coiling, the Onyx liquid embolic system (Medtronic, Irvine, California, USA) can be delivered to finish embolization.

Fig. 1.

Microcatheter parameters. In this image, the parameters of the SL-10, Echelon-10, Marathon and Apollo microcatheters are shown.

Fig. 3.

Images from Patient 1. (A) Three-dimensional (left panel) and 2-dimensional (right panel) DSA images of the right VA with the best degree of projection showing that a dissecting aneurysm (arrows) arose from a small branch of the PCA; (B) Panel 1: Roadmap image showing the Apollo microcatheter with a 3 cm detachable tip (arrow) into the aneurysm; Panel 2: Roadmap image showing coiling via an Apollo microcatheter; Panel 3: X-ray image showing that the marker of the coil push lever matched the proximal marker of the detachable point of the Apollo microcatheter well; Panel 4: X-ray image showing that the aneurysm was occluded by the coil and Onyx; Panels 5 and 6: After the Apollo microcatheter was withdrawn, unsubtracted (Panel 5) and subtracted (Panel 6) DSA images revealed that the aneurysm was obliterated. (C) Lateral (left panel) and anterior posterior (right panel) views of the DSA images of the right VA showing that collateral circulation from the posterior circulation to the anterior circulation was not impaired and that the posterior circulation could still provide sufficient blood flow to the anterior circulation. (D) Postoperative Xper-CT image showing no abnormalities.

Abbreviations: CT, computed tomography, DSA, digital subtraction angiography, PCA, posterior cerebral artery, R, right, VA, vertebral artery.

However, the Marathon microcatheter has only 1 distal marker, making coiling inconvenient. The Apollo microcatheter has all the properties of the Marathon microcatheter [4]. The Apollo microcatheter also importantly may have a 3 cm detachable tip with 2 markers. Under X-ray, the detachable point of the coil on the push lever can match the proximal marker on the Apollo microcatheter with a 3 cm detachable tip well. Therefore, the Apollo microcatheter with a 3 cm detachable tip has angiographic characteristics similar to those of routine coil-delivery microcatheters, which makes the Apollo microcatheter with a 3 cm detachable tip convenient for delivering and detaching coils. Because the new technique is useful and has rarely been reported, we reported 2 typical cases involving the use of this technique.

Presentation of cases

Case 1

A 59-year-old male experienced sudden-onset severe headache, which lasted for 1 hour. He had a 2-year history of brain infarction; no neurologic deficit remained. He had no history of hypertension or diabetes mellitus. During the neurological examination, the patient was awake and able to answer questions correctly. He had a stiff neck. He had grade V muscle strength in his upper and lower limbs, and no abnormal reflexes or hypoesthesia was detected. The Hunt–Hess grade was II. Computed tomography (CT) revealed a subarachnoid hemorrhage (SAH) focused on the right ambient cistern and an old infarction of the left frontal lobe (Fig. 2A). CT angiography revealed a right occluded common carotid artery and an aneurysm that arose from the right posterior cerebral artery (PCA) (Fig. 2B). By identifying the relationship between the aneurysm and the SAH, the aneurysm was found to be in the SAH center. The SAH should arise from aneurysm rupture of the right PCA. Endovascular treatment (EVT) was planned and performed due to the deep location and availability of the technique.

Fig. 2.

Images from Patient 1. (A) Left panel: CT image showing subarachnoid hemorrhage focusing on the right ambient cistern; Right panel: CT image showing old left frontal infarction (ellipse). (B) Left panel: CT angiography image showing that the right common carotid artery was occluded; Right panel: Maximum-intensity projection of CT angiography showing an aneurysm (arrow) that arose from the right PCA. (C) Left panel: DSA image showing moyamoya-like changes in the left MCA; Right panel: DSA image showing a normal left VA. (D) Panel 1: DSA image showing the occluded right common carotid artery (asterisk); Panels 2 and 3: DSA images showing the right ECA (arrows) anastomosed with the right VA and anterior circulation with blood flow from posterior circulation via collateral circulation (asterisks).

Abbreviations: CT, computed tomography, DSA, digital subtraction angiography, ECA, external carotid artery, L, left, MCA, middle cerebral artery, PCA, posterior cerebral artery, R, right, VA, vertebral artery.

Under general anesthesia, digital subtraction angiography (DSA) was performed and revealed a moyamoya-like change in the region of the left middle cerebral artery; the right common carotid artery was occluded, and the posterior circulation provided blood flow to the right internal carotid artery region (Fig. 2, Fig. 2). A dissecting aneurysm on the branch of the right PCA was confirmed (Fig. 3A). After the 5F distal access catheter reached the vertebrobasilar junction, an Apollo microcatheter with a 3 cm detachable tip was guided by a Synchro 10 microguidewire (Stryker Neurovascular, Fremont, CA, USA) into the aneurysm. The aneurysm was coiled with a 3 mm-8 cm Jasper ®SS-10 coil (Achieva Medical Co., Ltd., Shanghai, China). Then, 0.5 mL of Onyx-18 was delivered via the Apollo microcatheter. The aneurysm was obliterated, and the Apollo microcatheter was subsequently withdrawn (Fig. 3B). The collateral circulation from the posterior circulation to the anterior circulation was not impaired (Fig. 3C). Immediate postoperative Xper-CT did not reveal hemorrhage (Fig. 3D). The patient recovered well after the procedure and had no complications from EVT. At the 3-month telephone follow-up after EVT, the patient was deemed to have fully recovered and had returned to work.

Case 2

A 51-year-old male experienced intermittent mild headache for 1 month. He had no family history of intracranial vascular disease. On neurological examination, he was able to answer questions correctly. He had grade V muscle strength in his upper and lower limbs, and no abnormal signs were detected. Head magnetic resonance imaging revealed a BAVM at the base of the frontal lobe (Fig. 4A). Magnetic resonance venography revealed venous aneurysmal dilations in the draining vein (Fig. 4B). The BAVM was Spetzler–Martin grade II. Venous aneurysmal dilations indicate high venous pressure and resistance of the BAVM. There was a risk of rupture, and EVT was planned.

Fig. 4.

Images from Patient 2. (A) T2 sequence of magnetic resonance imaging showing flow voids (ellipse) at the base of the left frontal lobe, indicating a BAVM. (B) Magnetic resonance venography image showing 2 aneurysmal dilatations (arrowheads) on the draining vein. (C) Anterior posterior (left panel) and lateral (right panel) views of the DSA image of the left ICA confirming the BAVM. Multiple feeding arteries arose from the polar frontal and orbitofrontal arteries, and 2 draining veins, including major and minor superficial frontal cortical veins (numbers 1 and 2 in the right panel) into the superior sagittal sinus, were dilated and tortuous, accompanied by 2 aneurysmal dilatations (blue arrowheads). (D-F) Three-dimensional (Panel D) DSA of the left ICA, early arterial phase DSA of the left ICA (Panel E) and selective angiography of the Apollo microcatheter in the ACA (Panel F) revealed a fistulous structure (red arrows) in the nidus; In Panel F, the arrowheads indicate the major draining vein.

Abbreviations: ACA, anterior cerebral artery; BAVM, brain arteriovenous malformation; DSA, digital subtraction angiography; ICA, internal carotid artery; L, left.

Under general anesthesia, after the distal access catheter reached the cavernous segment of the internal carotid artery, DSA confirmed a medium-sized BAVM located at the base of the left frontal lobe. The feeding arteries arose from the polar frontal and orbitofrontal arteries, 2 draining veins flowed into the superior sagittal sinus, and the major vein was dilated and tortuous (Fig. 4C). In the nidus, there was a fistulous structure (Figs. 4D-F). EVT was performed according to the following. First, an Apollo microcatheter with a 3 cm detachable tip was guided by a Synchro 10 microguidewire and reached the fistulous structure. The fistulous structure was coiled with a 2-6 cm Jasper® SS-10 coil via the Apollo microcatheter (Fig. 5A). Then, 2 mL of Onyx-18 was delivered to partially embolize the BAVM. After EVT, the Apollo microcatheter was withdrawn (Fig. 5B). Immediate postoperative Xper-CT did not reveal hemorrhage (Fig. 5C) and the patient did not experience any notable postoperative events. He was discharged without any complications from EVT. At 3 months after EVT, he was normal. A follow-up CT revealed no abnormity (Fig. 5D). Radiotherapy for the residual BAVM was suggested.

Fig. 5.

Images from Patient 2. (A) Panel 1: Roadmap image showing the Apollo microcatheter positioned in the main feeding artery of the BAVM and accessing the fistulous structure (asterisk) in the nidus; Panels 2, 3, and 4: X-ray images showing coil delivery and detachment via the Apollo microcatheter. The arrows indicate the proximal marker of the detachable point of the Apollo microcatheter, the arrowheads indicate the distal marker, and the distance between the 2 markers is 3 cm. The marker of the coil push lever matched the proximal marker of the detachable point of the Apollo microcatheter. (B) Panel 1: DSA image of the left ICA showing that the fistulous structure (arrow) was coiled; Panel 2: Roadmap image showing that the Apollo microcatheter was withdrawn after casting Onyx. The arrow indicates the proximal marker, the arrowhead indicates the distal marker; Panel 3: X-ray image showing Onyx casting in the nidus; Panel 4: DSA image of the left ICA showing that the nidus of the BAVM was partially embolized. (C) Postoperative Xper-CT image showing no abnormalities. (D) Left panel: Three-month follow-up CT image showing no abnormality; Right panel: Reconstructed skull CT image showing the location of the Onyx casing (ellipse).

Abbreviations: CT, computed tomography, DSA, digital subtraction angiography, ICA, internal carotid artery.

Discussion

Intracranial peripheral aneurysms are remotely located distal to the major branch points of the circle of Willis and the vertebrobasilar system [5]. These lesions often rupture spontaneously, so treatment is commonly needed [6]. Surgical treatment is challenging for these peripheral aneurysms because of their distal and deep location. Currently, as an alternative to open surgery, parent artery occlusion of EVT by coiling with/without the combination of liquid embolic agents can play an important role. However, accessing these aneurysms with routine coil-delivery microcatheters to perform coiling is difficult because of the thin parent artery of the aneurysm (Fig. 6).

Fig. 6.

Coiling by Echelon and Marathon microcatheters. (A) Coiling by an Echelon microcatheter: Panel 1: Three-dimensional DSA image of the VA showing an aneurysm (asterisk) in the distal PICA; Panel 2: Roadmap image showing that the Echelon-10 microcatheter (arrow) cannot catheterize the thin parent artery (red lines) of the aneurysm (asterisk); Panel 3: Unsubtracted DSA image showing the branch that gave off the parent artery of the aneurysm had to be coiled; Panel 4: DSA image of the VA showing that the aneurysm (asterisk) cannot be seen. (B) Coiling by a Marathon microcatheter: Panel 1: Three-dimensional DSA image of the ICA showing 2 tandem aneurysms (arrows) on the distal PCA; Panel 2: Roadmap images showing that the Marathon microcatheter (arrows) catheterized the thin parent artery to perform coiling; Panel 3: Six-month follow-up DSA image of the ICA showing that the 2 aneurysms could not be detected.

Abbreviations: DSA, digital subtraction angiography, ICA, internal carotid artery, PCA, posterior cerebral artery, PICA, posterior inferior cerebellar artery, VA, vertebral artery.

For BAVMs, EVT can embolize flow-related aneurysms or reduce the size of the nidus to facilitate surgical resection or radiosurgery [7]. BAVMs can be associated with intranidal fistulous structures, and these fistulas pose a challenge for EVT, surgical treatment, and stereotactic radiosurgery [8]. When EVT is performed, the fistulous structure should be coiled first to prevent the migration of liquid embolic agents into the cerebral venous system or draining veins too early. In addition, coiling fistulous structures can increase the penetration of liquid embolic agents into the nidus [9]. Due to the tortuosity of the feeding artery and the remote location of the fistulous structure in the BAVM, accessing the fistulous structure in the nidus with routine coil-delivery microcatheters to perform coiling is difficult because these microcatheters are too thick, stiff and short to reach the fistulous structure.

For intracranial peripheral aneurysms and fistulous structures in the BAVM, the thin and soft flow-directed Marathon and Apollo microcatheters, with a distal inner diameter of 0.013 and 165 cm long, enable access to these lesions [3]. Since the approval of the Apollo detachable-tip microcatheter by the U.S. Food and Drug Administration in 2014, it has been available in China. The Apollo microcatheter has 2 radiopaque marker bands to visualize the position of the microcatheter and the detachment zone. The Apollo detachable tip microcatheter has 1.5 and 3 cm detachment tip lengths. After the structures are accessed, certain types of coils can be delivered via the Marathon and Apollo microcatheters to perform coiling, such as the Kaneka ED extrasoft coil (Kaneka, Kanagawa, Japan) and the Barricade coil (Blockade Medical, Irvine, CA, USA) [[10], [11], [12]]. However, these coils are unavailable in China. A Jasper ®SS-10 coil is available and matches with the Marathon and Apollo microcatheters well.

During coiling, the use of microcatheters with 2 radiopaque markers 3 cm apart was important for determining whether the coil was completely inside the aneurysm or a fistulous structure. However, the Marathon microcatheter has only 1 tip marker; thus, more care and patience are needed to determine the position of the coils. The Apollo microcatheter with a 3 cm detachable tip has 2 radiopaque markers, and the detachable point of the coil on the push lever can match the proximal marker on the Apollo microcatheter well. Therefore, on X-ray image, the Apollo microcatheter with a 3 cm detachable tip had angiographic characteristics similar to those of routine coil delivery microcatheters, which increased the convenience of EVT. In addition, after coiling, Onyx can be delivered. A break point in the distal aspect allows separation of the device tip if it becomes entrapped in the Onyx cast secondary to reflux of the Onyx, which makes microcatheter retrieval more controlled and less traumatic during device extraction [13].

The use of Apollo microcatheters to deliver coils, followed by delivery of Onyx, provides new ideas for treating intracranial vascular diseases, such as embolizing high-grade dural arteriovenous fistulas [11] and veins of Galen malformations [10] and performing parent artery occlusion by coiling and casting Onyx [14]. However, the application of this new technique has limitations. Firs, not all types of coils and liquid embolic agents are compatible with the Apollo microcatheter. Second, although the Apollo microcatheter has a stainless-steel proximal coil for structural support and nitinol distal braiding that provides high kink resistance, the tip of the Apollo microcatheter is still soft and not designed for coiling. If it is kicked out of the aneurysm or fistula during coiling, then coiling may fail; therefore, short soft coils are recommended. In the future, if the manufacturer can produce a type of Apollo microcatheter with a stiff distal tip with stronger support, the technique could be more promising.

Conclusion

When routine coil-delivery microcatheters cannot reach lesions in remote areas, Apollo microcatheters with a 3 cm detachable tip can be used to deliver coils, followed by casting Onyx. These findings can be used as a reference for treatment protocols for complex intracranial vascular diseases necessitating the use of both coiling and casting Onyx during surgery.

Ethics approval

Ethics approval was not needed in our institution, as the manuscript was a case report.

Patient consent

A written and informed consent was obtained from the patient for publication of this case report.