Purpose 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. Methods 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. Results 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). Conclusion 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.
|Number of pages||9|
|Journal||Magnetic Resonance in Medicine|
|Publication status||Published - 2014|
- magnetic resonance
- pulse wave velocity
- real time phase contrast
- respiratory maneuver