An ultrasound velocity assessment technique was validated, which allows the estimation of velocity components perpendicular to the ultrasound beam, using a commercially available ultrasound scanner equipped with a linear array probe. This enables the simultaneous measurement of axial blood velocity and vessel wall position, rendering a viable and accurate flow assessment. The validation was performed by comparing axial velocity profiles as measured in an experimental setup to analytical and computational fluid dynamics calculations. Physiologically relevant pulsating flows were considered, employing a blood analog fluid, which mimics both the acoustic and rheological properties of blood. In the core region (|r|/a \ 0.9), an accuracy of 3 cm s -1 was reached. For an accurate estimation of flow, no averaging in time was required, making a beat to beat analysis of pulsating flows possible.
) and clopidogrel (600 mg, 12 h before PCI): 15 with coronary angiography (CA group), 40 with PCI (PCI group), and 10 with rotational atherectomy plus PCI (RA group). PR was assessed by ADP, high-sensitivity ADP and thrombin receptor activator peptide 6 tests prior to, immediately after and 24 h after the procedure. E-selectin and ICAM-1 were assessed prior to and immediately after the procedure. In vitro, PR was measured during pulsatile blood flow at baseline, after balloon inflation and after stent implantation in six porcine carotid arteries and five plastic tubes. PR declined in the CA group, but significantly increased in the PCI and RA groups immediately postprocedure, and decreased to baseline at 24 h. DPR increased across the three groups (P < 0.0001). In the PCI group, DPR was directly related to total inflation time (r = 0.435, P = 0.005) and total stent length (r = 0.586, P < 0.001). The change in Eselectin significantly and inversely correlated with DPR (P < 0.001). No correlation was found with sICAM-1. PR increased significantly more in patients with PMI than in patients without PMI (P = 0.013). In vitro, platelet activation was observed in the presence of carotid arteries but not in the presence of plastic tubes. Conclusions: Despite dual antiplatelet therapy, PCI affected platelet function proportionally to procedural complexity and the extent of vascular damage.
A novel axial velocity profile integration method, obtained from ultrasonic perpendicular velocimetry, for flow estimation in curved tubes was validated. In an experimental set-up, physiologically relevant curved geometries and flows were considered. Axial velocity profile measurements were taken by applying particle imaging velocimetry-based methods to ultrasound data acquired by means of a linear array transducer positioned perpendicular to the axial velocity component. Comparison of the assessed asymmetric velocity profiles to computational fluid dynamics calculations showed excellent agreement. Subsequently, the recently introduced cos hintegration method for flow estimation was compared to the presently applied Poiseuille and Womersley models. The average deviation between the cos h-integration-based unsteady flow estimate and the reference flow was about 5%, compared to an average deviation of 20% for both the Poiseuille and Womersley approximation. Additionally, the effect of off-centre measurement was analysed for the three models. It was found that only for the cos h-integration method, an accurate flow estimation is feasible, even when it is measured off centre.
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