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Magn Reson Med. 2014 Jul;72(1):202-10. doi: 10.1002/mrm.24890. Epub 2013 Jul 30.

Beat-to-beat variation in pulse wave velocity during breathing maneuvers.

Author information

1
Division of Imaging Sciences and Biomedical Engineering, King's College London, St. Thomas' Hospital, London, UK.

Abstract

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.

KEYWORDS:

Mueller; Valsalva; magnetic resonance; pulse wave velocity; real time phase contrast; respiratory maneuver

PMID:
23922308
DOI:
10.1002/mrm.24890
[Indexed for MEDLINE]
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