Gaddum Nicholas R, Schaeffter Tobias, Bührer Martin, Rutten Marcel, Smith Lorna, Chowienczyk Philip J, Beerbaum Philipp B J
Division of Imaging Sciences and Biomedical Engineering, King's College London, St. Thomas' Hospital, London, UK.
Magn Reson Med. 2014 Jul;72(1):202-10. doi: 10.1002/mrm.24890. Epub 2013 Jul 30.
Thoracic pulse wave velocity (PWV) variation due to modulated trans-mural pressure (TMP) may indicate mechanical properties of the aorta. Our aim was to measure beat-to-beat thoracic PWV and TMP to observe its normal variation during respiratory maneuvers.
We validated PWV measurements from a real-time velocity projection MRI scan in a pulsatile phantom. A volunteer study showed inter-scan repeatability of steady-state PWV, and observed PWV variation when performing Mueller and Valsalva maneuvers. Synchronized to the real-time projection velocity data, TMP was measured using a mouth piece and pressure sensor arrangement monitoring the intra-thoracic pressure and a single arterial pressure measurement.
In the phantom, beat-to-beat PWV derived from real-time projection (5.33 ± 0.32 m s(-1) ) agreed well with experimentally derived PWV using ultrasound probes (5.72 ± 0.50 m s(-1) ). The within-subject PWV variation between scans was 0.28 m s(-1) . Volunteers' PWVs increased during Mueller maneuver (TMP increase of 14.67 ± 10.69 mmHg) by 32% (P < 0.001), and during Valsalva maneuver (TMP decrease of TMP = 17.01 ± 12.91 mmHg), PWV response were inconsistent with an average increase of 14% (P < 0.05).
Gating TMP to beat-to-beat PWV allows insight into how aortic stiffness varies with strain. However, quantifying nonlinear arterial stiffness requires real-time arterial pressure measurement.
由于跨壁压力（TMP）调制引起的胸段脉搏波速度（PWV）变化可能表明主动脉的力学特性。我们的目的是测量逐搏胸段PWV和TMP，以观察其在呼吸动作期间的正常变化。
我们在搏动模型中验证了来自实时速度投影MRI扫描的PWV测量。一项志愿者研究显示了稳态PWV的扫描间重复性，并观察了在进行米勒动作和瓦尔萨尔瓦动作时PWV的变化。与实时投影速度数据同步，使用口件和压力传感器装置测量TMP，该装置监测胸内压力和单次动脉压测量。
在模型中，来自实时投影的逐搏PWV（5.33±0.32 m s⁻¹）与使用超声探头实验得出的PWV（5.72±0.50 m s⁻¹）非常吻合。扫描间受试者内PWV变化为0.28 m s⁻¹。志愿者的PWV在米勒动作期间（TMP增加14.67±10.69 mmHg）增加了32%（P<0.001），而在瓦尔萨尔瓦动作期间（TMP降低TMP = 17.01±12.91 mmHg），PWV反应不一致，平均增加14%（P<0.05）。
将TMP与逐搏PWV进行门控可深入了解主动脉僵硬度如何随应变变化。然而，量化非线性动脉僵硬度需要实时动脉压测量。
