Carotid hemodynamic response to external pressure and comparison with induced-stenosis progression: a fluid-structure interaction study.

Non-invasive stenosis detection has always been difficult. A new concept of applying external pressure over the artery was compared with stenosis growth in this computational study. When stenosis develops, the artery constricts, obstructing blood flow in that area. Under external pressure, the constricted artery behaves similarly. The current fluid-structure interaction study compares the hemodynamic parameters of a stenosed artery and an artery subjected to external pressure. Significant similarities were discovered when the velocity profile and arterial displacement for both scenarios were compared. This study can be used to characterise stenosis experimentally while remaining non-invasive.

Modeling, Simulation and Validation of Alteration in Blood Flow and Regional Oxygenation Under Arterial Occlusion.

The paper presents the mathematical modeling along with an experimental approach for the identification of arterial occlusion condition. Arterial occlusion occurs due to development of constriction and/or thrombus in the lumen of the artery. A geometry of the thrombus has been modeled for the analysis of the arterial occlusion condition in modeling part. The proposed model of the thrombus has been simulated using Comsol® multiphysics considering different hemodynamic parameters. Variation in regional oxygen saturation (rSO2) of the arterial occlusion condition has been validated with experimental process, where occlusion of the artery has been done by applying external pressure. The experimental study has been conducted to monitor alteration in rSO2 level profile for occlusion using near infrared spectroscopy (NIRS) methodology. NIRS signal data has been collected from twenty-three subjects with no reported musculoskeletal, psychiatric, or any other neurological deficits using Mespere NeurOs® oxymeter. Experimental data reveal that the oxygenation level decreases considerably due to arterial occlusion as compared to the healthy condition at 95% of confidence interval (p < .05). Dynamic time warping algorithm reveals that variation in rSO2 due to proposed thrombus geometry has more similarity with experimental study.

Measurement of Near infrared Spectroscopy based Biomarkers under in-vitro Ischemic stroke condition.

Near infrared spectroscopy (NIRS) is an optical method which has been used widely to measure the change in the blood chromophores. Abrupt change in blood chromophore viz, oxyhemoglobin [hbo2] and deoxyhemoglobin [hb] happens in ischemia stroke condition, which occurs due to impairment of the oxygenated compounds viz, oxygen and glucose. The current study presents measurement and analysis of near infrared spectroscopy (NIRS) based regional oxygenation level biomarkers Viz., change in regional blood volume index [Formula: see text] and change in regional oxygen saturation [Formula: see text]. To measure these NIRS biomarkers dynamic phantom has been designed in such a way that, it mimics the ischemic stroke condition in-vitro by continuously changing (decrease, increase) the oxygenation level of human blood sample in the closed loop arterial system of dynamic phantom. Continuous decline of the [Formula: see text] % and [Formula: see text] 5% has been observed of the average reading of the samples in an ischemic stroke condition, while 15% and 2% increment has been recorded in reversal of ischemic stroke condition, by increasing the oxygenation level of the arterial system. Correlation between biomarkers in ischemic stroke condition has been found strongly positive (r=56%) and regular residual percentage error in measurement has been measured which has found under 10%. Clinical Relevance- This help in understanding and characterizing the ischemic stroke. Biomarker's trend can be use for classification of stroke types.