The application of large amplitude oscillatory stress in a study of fully formed fibrin clots

Abstract

The suitability of controlled stress large amplitude oscillatory shear (LAOStress) for the characterisation of the nonlinear viscoelastic properties of fully formed fibrin clots is investigated. Capturing the rich nonlinear viscoelastic behaviour of the fibrin network is important for understanding the structural behaviour of clots formed in blood vessels which are exposed to a wide range of shear stresses. We report, for the first time, that artefacts due to ringing exist in both the sample stress and strain waveforms of a LAOStress measurement which will lead to errors in the calculation of nonlinear viscoelastic properties. The process of smoothing the waveforms eliminates these artefacts whilst retaining essential rheological information. Furthermore, we demonstrate the potential of LAOStress for characterising the nonlinear viscoelastic properties of fibrin clots in response to incremental increases of applied stress up to the point of fracture. Alternating LAOStress and small amplitude oscillatory shear measurements provide detailed information of reversible and irreversible structural changes of the fibrin clot as a consequence of elevated levels of stress. We relate these findings to previous studies involving large scale deformations of fibrin clots. The LAOStress technique may provide useful information to help understand why some blood clots formed in vessels are stable (such as in deep vein thrombosis) and others break off (leading to a life threatening pulmonary embolism).

Recycling and rheology of poly(lactic acid) (PLA) to make foams using supercritical fluid

“…113 If cone-plate geometry was used, the results could be different. It should also be noted that the upturn could lead to large amplitude oscillatory shear (LAOS) flow 114,115 and orientation of order in the flow. 116 Since LAOS and the comparison between parallel-plate and cone-plate geometries are out of the scope of this study, this was not explored any further.…”

Blood Clot Phenotyping by Rheometry: Platelets and Fibrinogen Chemistry Affect Stress-Softening and -Stiffening at Large Oscillation Amplitude

“…However, only a single deformation amplitude is applied, and the full behavior of fibrin networks is not captured. Measuring clot firmness at a broad range of deformation would add important information on the network behavior because fibrin networks follow different stretching regimes that alternate with the applied strain [ 26 , 27 , 30 , 31 , 32 ]. Including the non-linear behavior into a test protocol also makes sense insofar as blood flow is dynamic in the body, which requires a dynamic mechanical response from the clots.…”

“…By applying a more stable control mechanism in the non-linear regime, LAOS testing is performed in most instances by controlling the strain as the sinusoidal input function and measuring the resulting stress function (LAOStrain). For shear stiffening materials like biological fiber networks, controlling the stress as sinusoidal input function (large amplitude sweep test, LAOStress) [ 41 , 42 ], and measuring the resulting strain function is not a challenge, as pointed out by Lamer and co-authors [ 31 ]. LAOStress is superior to LAOStrain because the applied stresses can be related to the hemodynamic forces that act on blood clots.…”

Preface to Special Topic: Papers from the Institute of Non-Newtonian Fluid Mechanics Meeting, Lake Vyrnwy, 2017

“…The papers presented here include the development of passive non-linear microrheology for measuring the non-equilibrium properties of complex fluids 1 and a method for correcting inertial artefacts in a gel point measurement using combined motor-transducer rheometers. 2 The paper by Lamer et al, 3 describing the use of controlled stress large amplitude oscillatory shear (LAOS) to reveal detailed information of reversible and irreversible structural changes in fibrin clots, received the British Society of Rheology-TA Instruments Award at the meeting for the best student poster as judged by the current president of the Society of Rheology, Professor Gareth McKinley and the immediate past president of the European Society of Rheology, Professor Mats Stading. On the subject of LAOS, Saengow and Giacomin 4 describe exact and unique analytical solutions for both normal stress differences in a LAOS measurement for the Oldroyd 8-constant framework.…”