There are two key steps in GDC embolization of intracranial aneurysms, the first is the accurate placement of the microcatheter and its ability to be fixed in the aneurysm cavity, and the second is the selection of the appropriate type and size of the micro-spring coil. For the first step, the following 3 aspects need to be accomplished: (1) Since the microcatheter is soft and must rely on the effective support of the guide catheter, the guide catheter should be inserted to the base of the skull in order to prevent the microcatheter from being excessively twisted within the vessel. (2) The head end of the microcatheter is molded into different shapes according to the angle made by the aneurysm and the aneurysm-carrying artery and the distance from the center of the aneurysm lumen to the side wall of the aneurysm-carrying artery. (3) With the cooperation of the microguide wire, the microcatheter is fed into the aneurysm cavity through the aneurysm opening, and the end of the microcatheter is kept at 1/3 to 1/2 of the aneurysm neck. Smaller aneurysms can be placed at the aneurysm neck, which has less resistance and facilitates the winding of the spring coil. In order to make the embolization process go smoothly, it is crucial to choose the right micro-spring coil. GDC embolization system has a variety of micro-spring coils to choose from, and there are two commonly used models, GDC-10 and GDC-18, each of which is divided into three specifications, i.e., single-diameter, double-diameter (2-D), and three-dimensional (3-D), with the single-diameter and double-diameter models being divided into the standard and the soft models.
Wide-necked aneurysm has always been the difficulty of endovascular embolization, how to prevent the micro-spring coil from protruding into the aneurysm-carrying artery is the key to occlude wide-necked aneurysm in a satisfactory stuffing, the following embolization techniques are used at present: (1) basketettechnique, firstly, one or more three-dimensional micro-spring coils are delivered into the aneurysm lumen, and then, after the release of the three-dimensional micro-spring coils, the spatial extensibility of the coils is used, so that the aneurysm can be closed in the aneurysm lumen. This technique is simple and easy to implement, the disadvantage of this technique is that sometimes the spring coils are still convex outward at the end of embolization. (2) Balloon-assisted reconstruction technique, in order to prevent the micro-spring coil from protruding into the aneurysm-carrying artery, after the microcatheter is inserted into the aneurysm cavity and then a non-detachable balloon catheter is inserted through the guiding catheter into the aneurysm opening, and the balloon is filled to block the aneurysm opening, and then the aneurysm is occluded by the first method, which is a better shaping technique, with the disadvantage of the need to block the blood flow. (3) Stent-assisted reconstruction technique, an arterial stent is released to cover the opening of the aneurysm, then a microcatheter is inserted into the aneurysm cavity through the mesh of the arterial stent, and a micro-spring coil is delivered to occlude the aneurysm. This technique solves the first two drawbacks, but the support of the dedicated stent is insufficient at present. In our group, two cases of wide carotid aneurysms were embolized by the first method, and the results were satisfactory embolization without the micro-spring coil protruding into the aneurysm-carrying artery.
Prevention and treatment of embolization complications: (1) Intraoperative aneurysm rupture: it is mostly caused by improper operation of microcatheter and microguidewire or puncture of the aneurysm wall when GDC is placed, which can lead to fatal consequences if not handled in time. Once it occurs, neutralize heparin and reduce blood pressure immediately, and if the tip of the microcatheter is in place, continue to fill the aneurysm with GDC until the aneurysm is solidly filled. In this group, one case of intraoperative aneurysm rupture occurred, after the above treatment, the condition was rapidly controlled, and a small amount of intracranial hemorrhage was confirmed by cranial CT scan, and the patient was given lumbar puncture, vasodilator and other treatments after the operation, and the patient was cured and discharged from the hospital within a short period of time without any neurological dysfunction. (2) Intraoperative vasospasm: subarachnoid hemorrhage and endovascular operation can induce vasospasm. Preoperative use of Nimotropin, good analgesic anesthesia during operation, application of high-resolution fluoroscopy and tracer technique (roadmapping), gentle operation and intraoperative use of poppycock can effectively prevent and relieve vasospasm. (3) Displacement of GDC: Before each time of GDC release, it is necessary to confirm the position of the microcatheter tip and the position of the GDC by guided catheterization to make sure that both of them are located in the aneurysm. In one case in our group, the tail end of GDC protruded into the aneurysm-carrying artery when the last GDC was dislodged, and the displaced GDC was removed and repositioned with a Lasso catheter without any adverse effects. (4) Aneurysm recanalization: it is mostly caused by incomplete embolization, which is mainly seen in huge or wide carotid aneurysms. Therefore, dense filling is emphasized during embolization, and long-term follow-up should be carried out, so that those who have recanalized the aneurysm can be re-embolized again, and the cure can be achieved.