In Vitro Evaluation
- Dylan Lightbody
Background
In vitro evaluation of MCS devices are tested using mock circulation loops (MCLs) which represent the human circulatory system. The MCL can be set to a specified condition such as a left heart failure or suction event to test a device's response. There are many types of MCL's including; one sided, complete, total artificial heart, ECMO and hybrid [1].
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Mock Circulation Loops
In vitro testing of devices is completed using a mock circulation loop (MCL). This is where the circulatory system is modelled and certain heart conditions can be simulated.
One Sided Loop
A one sided mock circulation loop is one that simulates either the pulmonary or systemic circuit. Some one sided loops are designed with the ability to be configured to simulate either circuit [1].
Complete Loop
A complete mock circulation loop represents both the pulmonary and systemic circuits.
Hybrid Loop
A hybrid mock circulation loop uses both hydraulic and computational modelling.
Working Fluid
The fluid used in a mock circulation loop needs to represent the density, viscosity and non-Newtonian properties of blood. A common solution is to use a combination of glycerol and water. The ratio of glycerol to water varies between research laboratories. Gossman, M.S et al. used a ratio of 2:1 of water to glycerol when testing the Heartware MVAD ventricular assist device [2].
References
[1] Gregory, S. et al. (2018). Mechanical Circulatory and Respiratory Support. London. United Kingdom. Elsevier Inc.
[2] Gossman, M. S. et al. (2016). In Vitro PET Imaging of a Miniature Ventricular Assist Device. Journal of Nuclear Medicine Technology. 44(3). 190-194.