Dynatek’s Firsts

by | Jul 29, 2010 | Uncategorized

Dynatek’s Firsts

The M6 Heart Valve Durability Tester:
After more than 20 years, the M6 is still considered the international gold standard in heart valve testers. It’s hard to beat the fact that the M6 has at one time or other been used to test nearly every heart valve available for implant in the world today. Pioneer Professor Milton Swanson (our founder), considered by many to be the world’s first true cardiovascular flow dynamicist, introduced this instrument using a combination of a bellows volume drive with tuned fluid oscillation. This allows the heart valves to be opened and closed fully while attaining targeted closing pressures without the need to completely stop a column of liquid. Another important characteristic is that the systemic pressure of the M6 can be raised to reduce the occurrence of cavitation during high speed testing, a particular problem with mechanical heart valves. In addition to evaluating the durability of heart valves, the M6 can be used to evaluate a variety of films, candidate leaflet materials, septal repair products and LVAD bladders.

First Commercially Available Vascular Graft Durability Tester:
Twenty years ago Dynatek introduced the SVP (Small Vascular Prosthesis Tester), which quickly became the instrument of choice in most vascular graft development laboratories. By combining electroplated bellows and robust mechanical engineering designs, the SVP paved the way for vascular durability testing.

First To Consider Biologically Relevant Test Conditions:
Dynatek was the first to introduce the concept of biologically relevant testing conditions during accelerated durability evaluations. Previously, vascular grafts and especially heart valves were tested at a variety of speeds and pressures to accelerate the failure modes as is commonly done in standard mechanical testing. The lack of predictable failure of the tested products indicated a need to change the approach. Dynatek was responsible for new thinking and protocols that looked at the specific conditions that the products would be exposed to, followed by the design of instruments to replicate those conditions.

First To Use Inserts in Porous Vascular Grafts:
Dynatek was the first to realize that the use of a thin-walled insert in a porous vascular graft could be used to replicate biological processes that normally reduce or eliminate seepage in porous grafts after implantation. Dynatek built these inserts, and after this the first durability experiments that properly evaluated the durability of Dacron and other porous grafts was possible.

First To Introduce Dynamic Internal Compliance:
In the evaluation of vascular grafts and/or products that go into the vasculature, Dynatek was the first to realize that one of the most important mechanical characteristics is the dynamic internal compliance. Previously, only external measurements were taken and often were acquired in a static mode. After a thorough literature search and years of research, Dynatek not only demonstrated the errors inherent in external measurements, particularly of a static nature, but designed instruments and protocols to evaluate this critically important characteristic.

First To Offer Electromagnetic Actuator:
Dynatek and its colleagues were the first to introduce a commercially available electromagnetically actuated mechanical tester. This device allowed for accurate high speed testing down in the sub milligram and micron ranges. This type of device is particularly useful in evaluating nano structures.

First To Develop Precise High Speed Photographic Verification Protocols and Procedures:
High speed photographic verification was first commercially used by Dynatek to fulfill customer needs to monitor the motion of implantable products such as stents during high speed testing. The secret to this evaluation is the recently published set of protocols that Dynatek generated to utilize this technology.

First To Use 5% to 7% Compliance:
5% to 7% dynamic internal compliance is a number that is widely used internationally to produce vascular replicates into which implantable cardiovascular products can be deployed for testing. Fifteen years ago, Dynatek presented research to the NHLBI and undertook a major review of all found publications involved with the compliance of natural vessels either in vivo or in vitro. Dynatek suggested an average number of 5% to 7% change in diameter per 100 mm Hg internal pressure at 72 BPM to reasonably represent those conditions found in vivo . Although somewhat still controversial, most laboratories internationally now use this target. Data generated in laboratories all over the world can now be compared to each other because of the utilization of this common compliance for the testing.

First Use of Precise Mock Arteries:
Dynatek was responsible for the first introduction of vascular mechanical models to test the performance and durability of products and devices that would be implanted into or used within the human vasculature. Dynatek now supplies models in both clear silicone as well as latex. The mechanical properties of the starting materials and the resultant mock arteries or models can be tuned along with their dimensions. Dynatek uses a variety of technologies including CT scans, MRIs, and SolidWorks stl files to generate dipping mandrels that are produced using a patented process that yields enormous versatility in producing silicone models.

First Velocity Flow Standard:
Dynatek introduced the first and still the only portable pulsatile velocity flow standard in the world. Most other devices can only produce an accurate flow rate, or volume per minute. The EchoCal produces a highly reproducible pulsatile sine wave accurate to within 2 1/2% of the set velocities. Far more important than simple flow studies, velocity is a number that determines such characteristics as cavitation, Doppler measurements and velocity versus time characteristics of pumping systems. This instrument can be used to calibrate or check the accuracy of any flow measuring systems that utilize velocity as their fundamental measurement, such as laser Doppler anemometers, medical ultrasound machines or any other measuring device.

First Commercially Available Pulsatile Artificial Heart Tester:
A commercially available pulsatile ventricular assist device (LVAD) durability and performance tester was first introduced by Dynatek. To our knowledge, this is still the only commercially available pulsatile circulatory support device tester in the world. Outfitted with silicone arteries and peripheral vessels as well as a computer controlled ventricular actuator, the PVAD line of tunable testers already has over 175,000 hours worth of testing to prove its reliability. With modular vascular resistance and compliance elements along with the tunable ventricle, the PVAD can attain virtually any pulsatile cardiovascular condition that might be needed to evaluate a circulatory assist device, such as an artificial heart (TAH).