论文部分内容阅读
Background/aim: In patients with acute central retinal vein occlusion (CRVO), dynamic angiographymay reveal the presence of pulsatile flow (termed here pulsat ile venular outflow, PVO)-within first order veins (that is, the large veins). The main goal of this study was to investigate the mechanism underlying PVO. Met hods: 10 patients with CRVO and PVO were included. Quantitative and qualitative analysis of venous flow on dynamic angiograms allowed the correlation, temporall y, of second and first order vein flow on the one hand, and venous flow and syst olic cycle on the other. Results: Analysis of the time-velocity curve showed th at (1) the onset of arterial systole preceded the onset of PVO by less than 0.08 seconds (n=5); (2) PVO onsetwas simultaneous to the time of onset of minimal fl ow (Vmin) in first order veins (n=10); (3) the time of onset of maximal flow (Vm ax) in first order veins occurred 0.20-0.44 seconds after the onset of PVO (n=6 ). Conclusions: During CRVO with severe reduction in blood flow, the presence of PVO is the result of the existence of a distinct haemodynamic regimen in first and second order veins. These data support the hypothesis that second order vein s flow is synchronous with the arterial flow, while the delayed peak flow in fir st order veins may reflect the consequences of the delayed IOP curve and/or of i ntermittent venous compression.
Background / aim: In patients with acute central retinal vein occlusion (CRVO), dynamic angiography show the presence of pulsatile flow (termed here pulsat ile venular outflow, PVO) -within first order veins (that is, the large veins). The main goal of this study was to investigate the mechanism underlying PVO. Met hods: 10 patients with CRVO and PVO were included. Quantitative and qualitative analysis of venous flow on dynamic angiograms allowed the correlation, temporall y, of second and first order vein flow on the one hand, and venous flow and syst olic cycle on the other. Results: Analysis of the time-velocity curve showed th at (1) the onset of arterial systole preceded the onset of PVO by less than 0.08 seconds (n = 5); (2) PVO onsetwas simultaneous to the time of onset of minimal fl ow (Vmin) in first order veins (n = 10); (3) the time of onset of maximal flow (Vm ax) seconds after the onset of PVO (n = 6). Conclusions: During CRVO with seve re reduction in blood flow, the presence of PVO is the result of the existence of a distinct haemodynamic regimen in first and second order veins. These data support the hypothesis that second order vein s flow is synchronous with the arterial flow, while the delayed peak flow in fir st order veins may reflect the consequences of the delayed IOP curve and / or of i ntermittent venous compression.