Endovascular coiling

Endovascular coiling, or endovascular embolization, is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician inserting one or more into the aneurysm until it is determined that blood flow is no longer occurring within the space. It is one of two main treatments for cerebral aneurysms, the other being surgical clipping. Clipping is an alternative to stenting for bleeding.

Endovascular coiling was a developed through the synthesis of a number of innovations that took place between 1970 and 1990 in the field of electronics, neurosurgery, and interventional radiology. While the procedure itself has been and continues to be compared to surgical clipping, the development of the concept and procedure has resulted in it becoming the gold standard at many centers.

The first documented technique of using metal coils to induce thrombosis was accomplished by Mullan in 1974. Copper coils were inserted into a giant aneurysm through externally puncturing the aneurysm wall via craniotomy. Five patients died, with ten having satisfactory process. It did not gain popularity due to the specialized equipment required, in addition to the technique being unsuitable for many types of aneurysms. Later, in 1980, similar techniques were developed by Alksne and Smith using iron suspended in methyl methcrylate in a limited set of patients. There was no deaths in 22 consecutive cases with low morbidity. This technique also did not gain traction due to advances in clipping.

As a means of avoiding invasive methods, early endovascular interventions involved the usage of detachable and nondetachable balloon catheters to occlude the aneurysm while preserving the parent artery. Despite the innovative approach, the aneurysms were often found to adapt to the shape of the balloon itself resulting in higher incidents of aneurysm rupture. This procedure was deemed "uncontrollable" due to its high morbidity and mortality rate, but it demonstrated that the endovascular approach was feasible for many aneurysms. Endovascular coils would later be used in 1989 by Hilal et al., but these were short, stiff coils that offered no control, preventing dense packing of the aneurysm. Controllable microguidewire systems were later used.

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