Enhancement of angioplasty balloon performance through annealing

Angioplasty balloons are used to implement stenting of atherosclerosed blood vessels and put in place heart valve systems. The balloons are required to have thin walls and high burst pressure while having a given compliance (e.g., given balloon diameter at a nominal pressure). In this study 3 by 15 mm and an 8 by 30 mm balloons are formed through a micro-blow moulding process. The balloon forming machine process (BFMP) starts by stretching an extruded tubing of thermoplastic elastomer into a `parison¿ by means of a specially instrumented balloon forming machine. The BFMP is identified as a three step stretch micro blow moulding process, where the `parison¿ is stretched under pressure and at controlled temperatures to form a `balloon¿: Forming of the cylinders, forming of the balloon¿s cones and annealing of the balloon. In this article we show how the elastic and mechanical properties of the balloon can be fine tuned to the specifications of the medical suppliers. A balloon design method and suggestion for an in-line control method for the balloon forming process are also presented.