Transit Sensors Prove Viability of Heart Valves
Disposable, tamperproof temperature indicators record critical temperatures of delicate devices throughout shipping.
St. Jude Medical (St. Paul, MN) takes great care when shipping its Toronto SPV, an excised porcine aortic valve cross-linked using glutaraldehyde, to cardiovascular surgeons throughout the world. The valve, designed to replace a diseased, damaged, or malfunctioning human heart valve, is placed into a jar that is then put into an expanded polystyrene clamshell. The clamshell is then placed into an outer carton, and finally the entire package is put into a shipping container filled with polystyrene and cold packs.
But the company needed assurance that the packaging, insulation, and cold packs actually protected the valves from extreme temperatures. "With medical devices like ours, we feel we have to protect every shipment," says Corrine Hawkinson, senior project manager for St. Jude. "Freezing or prolonged exposure to heat above 45°C could irreversibly damage the biological tissue."
St. Jude decided to use temperature indicators to ensure that the valves did not encounter any extreme temperatures during shipping and handling. The firm chose ColdSnap transit thermometers, manufactured by Telatemp Corp. (Fullerton, CA), which consist of bimetallic sensing elements that snap at a predetermined temperature, turning indicator windows bright red. St. Jude used Telatemp's standard model that indicates whether the package was colder than 0°C and custom ordered another with the critical ascending temperature of 45°C. Both indicators are placed directly into the valve's clamshell packaging, which St. Jude designed with recesses to hold the self-adhesive indicators. To allow handlers to check the temperature of the valves during transit, St. Jude designed the outer carton that holds the clamshell with a cellophane window.
Hawkinson says that her firm ships anywhere from one valve to more than two dozen valves at a time. Even though they are rarely in transit for more than two days, she says she "has no illusions about any kid-glove treatment" for her packages. Because the packages may often be exposed to harsh conditions, Hawkinson prefers to use the ColdSnap mechanical indicators rather than more fragile chemical or glass indicators.
The ColdSnap standard transit thermometers are factory configured to provide a permanent, tamperproof record of a critical temperature. Units can also be custom configured, as Telatemp did for St. Jude Medical.