# Platinum in Medical Technology

## Platinum in the Minimal-Invasive Treatment of Aneurysms

Fig.1
Aneurysm treatment

Left: Aneurysm filled with Pt coil. Below right: Pt coil with primary and secondary forming.

Approximately 2-5 % of the European population have a so-called cerebral aneurysm. This aneurism is a localized ballooning of the wall of a blood vessel in the brain. In rare cases it can burst, leading to cerebral hemorrhage. If the ruptured aneurysm is in the arteries at the base of the brain, the hemorrhage has a high probability of being fatal. Even if the hemorrhage is not fatal, neurological disabilities generally remain, e.g. paralysis or problems with speech.

Since the middle 1990s, aneurisms have been treated minimal-invasively by the so-called "coiling" therapy. In this technique, extremely small coils of platinum alloys are positioned in the aneurysm through a catheter (Abb. 1) . These coils fill the aneurysm so that the blood flow in the aneurysm stops. As a consequence, the blood clots in the aneurysm. However, the thrombus created in this way stabilizes the wall of the blood vessel, thus preventing the danger of the aneurysm rupturing.

Materials used are platinum-tungsten (8 wt.-% tungsten) and platinum-iridium (10 wt.-% iridium). The wire diameter is typically between 30 and 70 $µm$. Initially, a primary coil is produced from the wire. This is then subjected to a secondary forming process and an annealing treatment to give it its secondary form.

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