Medical device testing
Application of biomaterials in direct blood contact results in activation of the blood coagulation system and in an inflammatory reaction. These responses of blood are due to the natural response of the host defence mechanism against foreign surfaces. Inadequate control by natural inhibitors results in pathological processes, such as microthrombi generation or thrombosis, bleeding complications, haemodynamic instability, fever, edema, and organ damage. These adverse events become manifest during prolonged and intensive foreign material contact with vascular implants and extracorporeal blood circulation.
HaemoScan is specialized in assessing blood compatibility. Blood compatibility or haemocompatibility relates to specific interactions between (bio)materials and circulating blood. HaemoScan performs in vitro tests with whole human blood to determine the compatibility of materials, devices, or material structures using our unique blood circulating model.
To get your blood contacting product or (bio)material CE or FDA certified, it has to be tested according to ISO 10993 standard part 4: “Selections of test for interaction with blood.” The revised ISO version refers to five test categories, indicating which categories are most relevant for each device. We can help you determine which assays to perform and achieve the ISO standards for blood compatibility.
Figure 1. Schematic of a Hemobile adapter for testing artificial heart valves.
Blood activation circulation model
The increased use of medical devices for temporary use or as implant in the blood circulation has resulted in increased demand for evaluation of complications brought about by these devices. This resulted also in new ISO requirements for testing, which were recently mandated. One important and extremely relevant aspect of testing of medical devices is the condition of blood exposure to the device. Anticoagulation and flow conditions must be as similar as possible as the clinical application to achieve relevant test results. For some devices, such as stents and catheters this implies high flow through or around the devices to obtain relevant shear stress conditions. Often, blood with other anticoagulants and under static conditions was incubated with the test device. Flow models for testing may consist of animal models or in vitro test systems. Animal models have the disadvantage of being expensive, time consuming and insensitive due to overwhelming short term effects of tissue damage.
In contrast to existing in vitro models we use the Hemobile, a simple mechanical device without air and without a pump to reduce blood damage and activation by the device. Moreover, the new device provides pulsatile flow in a frequency similar to the arterial circulation. This model enables us to measure haemocompatibility with fresh human blood. Because of its small volume multiple test circuits including tests and controls can be used at the same time.