International Centre for Circulatory Health, Imperial College, St Mary's Hospital Campus, 59-61 North Wharf Rd, Paddington, London W2 1LA, United Kingdom.
Hypertension. 2012 Sep;60(3):778-85. doi: 10.1161/HYPERTENSIONAHA.111.180604. Epub 2012 Jul 16.
Wave reflection is thought to be important in the augmentation of blood pressure. However, identification of distal reflections sites remains unclear. One possible explanation for this is that wave reflection is predominately determined by an amalgamation of multiple proximal small reflections rather than large discrete reflections originating from the distal peripheries. In 19 subjects (age, 35-73 years), sensor-tipped intra-arterial wires were used to measure pressure and Doppler velocity at 10-cm intervals along the aorta, starting at the aortic root. Incident and reflected waves were identified and timings and magnitudes quantified using wave intensity analysis. Mean wave speed increased along the length of the aorta (proximal, 6.8±0.9 m/s; distal, 10.7±1.5 m/s). The incident wave was tracked moving along the aorta, taking 55±4 ms to travel from the aortic root to the distal aorta. However, the timing to the refection site distance did not differ between proximal and distal aortic measurement sites (proximal aorta, 48±5 ms versus distal aorta, 42±4 ms; P=0.3). We performed a second analysis using aortic waveforms in a nonlinear model of pulse-wave propagation. This demonstrated very similar results to those observed in vivo and also an exponential attenuation in reflection magnitude. There is no single dominant refection site in or near the distal aorta. Rather, there are multiple reflection sites along the aorta, for which the contributions are attenuated with distance. We hypothesize that rereflection of reflected waves leads to wave entrapment, preventing distal waves being seen in the proximal aorta.
波反射被认为对血压的增加很重要。然而，远端反射部位的识别仍然不清楚。造成这种情况的一个可能解释是，波反射主要由多个近端小反射的融合决定，而不是源自远端外周的大离散反射。在 19 名受试者（年龄 35-73 岁）中，使用带有传感器的动脉内电线在主动脉上以 10cm 的间隔测量压力和多普勒速度，从主动脉根部开始。使用波强分析识别入射波和反射波，并对时间和幅度进行量化。平均波速沿主动脉长度增加（近端，6.8±0.9m/s；远端，10.7±1.5m/s）。入射波沿着主动脉移动，从主动脉根部到远端主动脉需要 55±4ms 的时间。然而，近端和远端主动脉测量部位之间的反射部位时间差异无统计学意义（近端主动脉，48±5ms 与远端主动脉，42±4ms；P=0.3）。我们在脉搏波传播的非线性模型中使用主动脉波进行了第二次分析。这与体内观察到的结果非常相似，也表明反射幅度呈指数衰减。在远端主动脉中或附近没有单一的主导反射部位。相反，主动脉上有多个反射部位，随着距离的增加，其贡献逐渐减弱。我们假设反射波的再反射导致波捕获，从而阻止近端主动脉中出现远端波。
