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In vitro testing in the age of transcatheter therapies

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By Rob Fraser

Advances in medical imaging modalities have allowed health care providers to offer a wide range of minimally invasive interventions which are implanted via catheters. Patients benefit tremendously from the minimally invasive nature of these options, which have caused an explosion of new devices to come under development. Patients are now demanding transcatheter approaches (albeit in the authors opinion perhaps too prematurely) which is putting pressure on traditional treatments. Like most disruptive technologies many peripheral industries are impacted when a new way of doing things becomes the norm. At ViVitro we specialize in conducting in vitro testing for a wide range of cardiovascular devices, and these advances in medical imaging have had a profound impact on our industry as well.

20 years ago if you wanted information on how a new cardiovascular device would perform, your main source of data would be in vitro testing, however now medical device companies are able to gain insights about their device from animal models that were not possible only a few decades ago. As a result, there is a new generation of device developers who have done much of their development purely in animal models. Ethical concerns aside, there are benefits to an animal focused approach since many devices require native anatomy that is challenging to re-create in a bench top setting. There are numerous reasons why there will always be a place for in vitro testing, but ones I find often overlooked are:

Durability Testing

Cardiovascular devices are typically placed around a beating heart or in a pulsatile flow environment. As a result cyclic loading is always applied to these devices creating the risk of a potential failure mechanism. Computational models can be useful in designing for fatigue but before a device is ever implanted in a patient, it must go through physical life cycle testing. The fastest way to get these results is to accelerate them in a laboratory setting, something impossible to do with animals. At ViVitro we are able to put a device through millions of cycles in a single day, something that would take almost a month in an animal.

Many clients have durability testing on their long list of things to accomplish before they call their design “finished” but my observation is that this is often left until too late in the design process. Clients will come with what they feel is a finalized design and are simply looking to check the durability box on their device submission only to find too late that they have a serious design flaw. At ViVitro we understand the motives behind this, durability tests can be lengthy and are perceived as expensive undertakings. For that reason we offer a range of service options to make it possible for companies to put prototypes through their paces early in the design process, preventing costly surprises when the finish line looks to be in sight.

Controlled Environment

As mentioned earlier animal testing has huge benefits including being able to test numerous different aspects of a device with a single animal. In addition to device hydrodynamic performance, data on biocompatibility, hemolysis, migration, etc can be examined at one time. While this is extremely useful, and cost effective for start-ups, it can also be very frustrating when things go wrong. If a problem is identified, the root cause ascertained, a solution implemented often the most conclusive way of determining if a device iteration will be a success is to conduct a controlled in vitro test. With the exception of mandatory testing requirements to validate a design for regulatory approval, many clients come to us looking to test a specific change in their device design.

In doing so many people familiar with animal models will approach a single test in the same multifaceted way their approach an animal study. The beauty of bench top testing is to simplify the problem down to a set of variables which can be controlled or altered in an exacting manner. At ViVitro our equipment makes this task a breeze, and we often create customization for clients interested in testing a unique aspect of their design. We also have a history of creating test protocols used in numerous different cardiac devices

In summary, advances in medical imaging have created a new generation of transcatheter medical devices. These devices revolutionize treatment for patients and are causing disruptions in many industries including ours. The imaging advances allow designers gain huge insights from animal models, which were previously the sole domain of bench top testing. For those clients new to in vitro testing I would recommend:

1) Test early – Contact an in vitro service or equipment vendor early in the design process to understand how they can help at all stages of your design. This will accelerate your design process and prevent costly late stage design stages

2) Simplify – Bench top testing allows designers to simplify a complex system down a bare minim of components to understand individual aspects of a device design. At ViVitro we are experts at justifying the simplifications necessary to test different aspects of a device design.

Rob Fraser, Msc., is a Standards Council of Canada (SCC) Member to ISO/TC 150/SC 2 – Cardiovascular implants and extracorporeal systems (ISO 5840) committee. ViVitro’s Lab Manager, Rob is one of only two Canadian members on the committee.