Revised standard goes to the heart of manufacturing differences

Standards must apply across a number of different situations. That is in their very nature. Manufacturing provides real challenges, particularly in niche applications involving highly-specialized manufacturing processes.

The question is often how to continue to adjust a standard to make sure that it continues to work effectively, whilst minimizing disruption to those processes.

Preferably without requiring unnecessary new work to make sure that the manufacturer remains compliant.

This third edition of the standard for sterilizing medical devices like biological heart valves (BS EN 14160 Liquid chemical sterilization of Health Care Products) is a good example of fine-tuning a standard to do exactly that.

Valves, clots and sterilization

The story of this standard goes back to the early 1990s when it began to be used for the very small range of medical devices that include a small part of animal origin, of which an example is biological heart valves.

Today, if a heart valve needs to be replaced, surgeons will choose between one of the latest versions of biological valves, which incorporate animal materials, or a mechanical heart valve made from man-made materials. The former behaves more like a natural human valve normally would, but they may not last as long as a mechanical valve made of metal and pyrolytic carbon.

Another important characteristic of mechanical heart valves, in particular, is that blood clots can form on them. If these are released into the bloodstream, they could have an adverse effect on the patient.

Before implantation, heart valves need to be sterile. Medical devices are most commonly sterilized with processes using ethylene oxide, radiation or moist heat during manufacturing. However, these treatments affected the performance characteristics of the animal tissue used in a biological valve.

A different sterilization procedure was required.

This alternative process – outlined in the current standard, BS EN 14160, now in its third edition – involves immersing the product into a liquid that contains chemical agents which ensure the microorganisms living on it are inactivated. This process turns non-sterile single-use products into sterile ones.

Accommodating all the little differences

There are only approximately ten manufacturers worldwide who make these products, often in small batch sizes of between ten and 50. Niche manufacturing indeed.

For each of them, it entails a small, manual process, as opposed to the kinds of big industrial operations that might be used for manufacturing syringes, for instance, where billions of units are sterilized every year.

Usually, there is clear guidance regarding the required conditions to use during a sterilization process.

For biological heart valves, however, the manufacturer chooses the agent or combination of agents that it needs, based on its own products. Each manufacturer uses a slightly different sterilization process for these single-use devices, such as employing a different combination of chemicals, for example.

Different processes, shared solution

Clearly, the issue is that the process used by one manufacturer may not be universally applicable to a different manufacturer’s products.

This standard was established to ensure that a universal, common method could be followed to show that the sterilization process is effective, by pioneering the common features of the action for killing microorganisms.

It considers the combined scientific knowledge of how microorganisms are killed, and then shortcuts that process for all manufacturers.

Now, no matter which bespoke, single-use medical device sterilisation method is used – or which combination of chemical agents is employed – during this niche manufacturing process, the outcome across the industry is the same. With BS EN 14160, one standard really does fit all. 

Buy this standard.