Short-term external counterpulsation augments cerebral blood flow and tissue oxygenation in chronic cerebrovascular occlusive disease

Fabricating a multi-component microfluidic system for exercise-induced endothelial cell mechanobiology guided by hemodynamic similarity

Generating precise in vivo arterial endothelial hemodynamic microenvironments using microfluidics is essential for exploring endothelial mechanobiology. However, a hemodynamic principle guiding the fabrication of microfluidic systems is still lacking. We propose a hemodynamic similarity principle for quickly obtaining the input impedance of the microfluidic system in vitro derived from that of the arterial system in vivo to precisely generate the desired endothelial hemodynamic microenvironments. First, based on the equivalent of blood pressure (BP) and wall shear stress (WSS) waveforms, we establish a hemodynamic similarity principle to efficiently map the input impedance in vivo to that in vitro, after which the multi-component microfluidic system is designed and fabricated using a lumped parameter hemodynamic model. Second, numerical simulation and experimental studies are carried out to validate the performance of the designed microfluidic system. Finally, the intracellular Ca²⁺ responses after exposure to different intensities of exercise-induced BP and WSS waveforms are measured to improve the reliability of EC mechanobiological studies using the designed microfluidic system. Overall, the proposed hemodynamic similarity principle can guide the fabrication of a multi-component microfluidic system for endothelial cell mechanobiology.

Cerebral venous steal equation for intracranial segmental perfusion pressure predicts and quantifies reversible intracranial to extracranial flow diversion

Cerebral perfusion is determined by segmental perfusion pressure for the intracranial compartment (SPP), which is lower than cerebral perfusion pressure (CPP) because of extracranial stenosis. We used the Thevenin model of Starling resistors to represent the intra-extra-cranial compartments, with outflow pressures ICP and Pe, to express SPP = Pd–ICP = FFR*CPP–Ge(1 − FFR)(ICP–Pe). Here Pd is intracranial inflow pressure in the circle of Willis, ICP—intracranial pressure; FFR = Pd/Pa is fractional flow reserve (Pd scaled to the systemic pressure Pa), Ge—relative extracranial conductance. The second term (cerebral venous steal) decreases SPP when FFR < 1 and ICP > Pe. We verified the SPP equation in a bench of fluid flow through the collapsible tubes. We estimated Pd, measuring pressure in the intra-extracranial collateral (supraorbital artery) in a volunteer. To manipulate extracranial outflow pressure Pe, we inflated the infraorbital cuff, which led to the Pd increase and directional Doppler flow signal reversal in the supraorbital artery. SPP equation accounts for the hemodynamic effect of inflow stenosis and intra-extracranial flow diversion, and is a more precise perfusion pressure target than CPP for the intracranial compartment. Manipulation of intra-extracranial pressure gradient ICP–Pe can augment intracranial inflow pressure (Pd) and reverse intra-extracranial steal.

Assessment of the value of 3D-DSA combined with neurointerventional thrombolysis in the treatment of senile cerebrovascular occlusion

Assessment of the value of three-dimensional digital subtraction angiography (3D-DSA) combined with neurointerventional thrombolysis in the treatment of senile cerebrovascular occlusion was investigated. A total of 129 patients with senile cerebrovascular occlusion admitted to the Affiliated Hospital of Zunyi Medical University from August 2015 to September 2017 were collected. Among them, 69 patients who underwent neurointerventional catheter thrombolysis under 3D-DSA were included in the study group, and 60 patients treated with neurointerventional thrombolysis were the control group. The levels of inflammatory cytokines IL-6, IL-1β and IL-8 in the two groups were measured by enzyme linked immunosorbent assay (ELISA) before treatment (T0), 7 days (7d) after treatment (T1) and 14 days (14d) after treatment (T2). The score of the National Institute of Health Stroke Scale and the clinical efficacy of patients in the two groups were compared before and after treatment, and Barthel index (BI) was used for investigation before and after treatment. The recurrence rate of disease in the two groups within 1 year was recorded. At T1, IL-6, IL-1β and IL-8 in the study group were significantly lower than those in the control group (P<0.05). The NIHSS score in the study group was lower than that in the control group after treatment (P<0.05). The BI score in the study group was significantly higher than that in the control group after treatment (P<0.05). After the prognostic follow-up, the disease recurrence rate of the study group was significantly lower than that of the control group (P<0.05). In conclusion, 3D-DSA combined with neurointerventional thrombolysis can significantly reduce the expression of inflammatory cytokines and improve the quality of life in patients with cerebrovascular occlusion, which has a high clinical value.