Department of Anesthesiology, Erasmus University Medical Centre, Rotterdam, the Netherlands.
PLoS One. 2018 Oct 10;13(10):e0204105. doi: 10.1371/journal.pone.0204105. eCollection 2018.
Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT.
PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus.
Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0-5.9 ms, 2) 2.8-5.1 ms, and 3) 1.6-12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236).
In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.
血管渡越时间（VTT）是脉搏波在动脉中的传播时间；它是动脉僵硬的衡量标准。由于可靠的非侵入性 VTT 测量较为困难，因此我们采用测量脉搏渡越时间（PTT）作为替代方法。PTT 定义为心电图 R 波与光电体积描记法（PPG）测量的远端位置的脉搏波到达之间的时间。心室电激活与主动脉瓣打开后产生的脉搏波之间的时间称为射前间期（PEP），是 PTT 的一个组成部分。本研究的目的是评估静息时 PEP 的变异性，以及 PTT 作为 VTT 近似值的准确性。
在三组 20 名志愿者中测量 PTT 并使用超声心动图评估 PEP：1）无心血管疾病且年龄<50 岁的对照组，2）年龄>50 岁的对照组，和 3）心血管危险因素组，定义为动脉高血压、血脂异常、肾功能衰竭和糖尿病。
每组的平均 PEP 为：1）58.5±13.0ms，2）52.4±11.9ms，和 3）57.6±11.6ms。然而，个体内的标准差要小得多，即 1）2.0-5.9ms，2）2.8-5.1ms，和 3）1.6-12.0ms。三组间的平均 PEP 无显著差异（p=0.236）。
总之，PEP 的个体内变异性较小。静息状态下 PTT 的变化很可能是 VTT 变化的结果，而不是 PEP 的变化。因此，静息时的 PTT 是监测动脉僵硬的一种简单、非侵入性和准确的 VTT 近似值。
