Interventional embolization procedures are increasingly popular among patients because they do not require craniotomy, are less invasive and less painful. So, how is a brain aneurysm interventional procedure done? First, meet the spring coil, a necessary tool for interventional procedures. This is a platinum wire with a soft texture and several specifications of different diameters, lengths and shapes, which is suitable for different shapes and sizes of cerebral aneurysms. The coil is connected to a metal push rod that is more than one meter long. Figure 6 Spring ring During the interventional embolization procedure, this pusher can push the spring ring at its front end into the aneurysm cavity. When the spring ring is stabilized in the aneurysm cavity, the connection between the pusher and the spring ring is released by electricity, water pressure or mechanical pulling, and this process is called spring ring uncoupling. If the shape and size of the coil is found to be incompatible with the aneurysm before the coil is uncoupled, the coil can be retrieved at any time with the pushrod and replaced with another coil that is more suitable. The released coil will remain in the aneurysm cavity and cannot be retrieved, then the pusher is withdrawn and the next coil is fed in until the aneurysm cavity is filled. The process of filling an aneurysm with a spring coil is like the process of packing a box with rocks. By the immediate formation of blood clots in the body. Generally speaking, an aneurysm with a dense embolism will have 20-30% of the total volume of the spring coil and the rest of the volume will be occupied by the thrombus. By dense embolization, we mean that the aneurysm is not visualized at all on postoperative cerebral angiography, which means that blood flow cannot enter the aneurysm, thus preventing bleeding from the aneurysm. Some people may ask, “Isn’t the aneurysm still there after the interventional embolization? In fact, cerebral aneurysm is not a tumor, but a “bulge” in the wall of blood vessel. The purpose of embolization is not to remove this “bulge”, but to fill it so that the blood flow will not enter the “bulge”. The purpose of our embolization procedure is not to remove this “bulge” but to fill it so that blood flow no longer enters the “bulge. Even in the case of craniotomy, the “bulge” is not removed, but is closed with a special clamp. After surgery, the aneurysm is still there, but as long as it is isolated from the bloodstream, it will not rupture and bleed. The procedure of interventional surgery is ultimately a catheterization process, and the conventional route is as follows: a thick catheter is punctured through one femoral artery, a guide catheter is placed, and the guide catheter is sent through the abdominal aorta and thoracic aorta into the cerebral artery (aneurysm-carrying artery) of the long aneurysm. A microcatheter (a thin catheter with a head end not much thicker than a sewing thread) is then fed into the aneurysm-carrying artery through this thick catheter, and the head end of the microcatheter is carefully fed into the aneurysm lumen under the guidance of a microguide wire, and the delivery and filling of the spring coil described earlier is accomplished through this microcatheter. Figure 7 Interventional embolization of cerebral aneurysm is also called “plumber” because the interventional operation is to manipulate various catheters to travel through the winding vessels of human body to reach the lesion. The entire interventional procedure is done under X-ray radiation, and we all understand the danger of X-ray to human body.