title: Arterial wave intensity and ventricular-arterial coupling by vascular ultrasound: rationale and methods for the automated analysis of forwards and backwards running waves.
abstract: Wave intensity (WI) in the circulation is estimated noninvasively as the product of instantaneous changes in pressure and velocity. We recorded diameter as a surrogate for pressure, and velocity in the right common carotid artery using an Aloka SSD-5500 ultrasound scanner. We developed automated software, applying the water hammer equation to obtain local wave speed from the slope of a pressure/velocity loop during early systole to separate net WI into individual forwards and backwards-running waves. A quality index was developed to test for noisy data. The timing, duration, peak amplitude and net energy of separated WI components were measured in healthy subjects with a wide age range. Age and arterial stiffness were independent predictors of local wave speed, whereas backwards-travelling waves correlated more strongly with ventricular systolic function than with age-related changes in arterial stiffness. Separated WI offers detailed insight into ventricular-arterial interactions that may be useful for assessing the relative contributions of ventricular and vascular function to wave travel.
authors.affiliation: Wales Heart Research Institute, Cardiff University, Cardiff, UK.
authors.forename: F
authors.initials: F
authors.lastname: Rakebrandt
authors.forename: C
authors.initials: C
authors.lastname: Palombo
authors.forename: J
authors.initials: J
authors.lastname: Swampillai
authors.forename: F
authors.initials: F
authors.lastname: Schön
authors.forename: A
authors.initials: A
authors.lastname: Donald
authors.forename: M
authors.initials: M
authors.lastname: Kozàkovà
authors.forename: K
authors.initials: K
authors.lastname: Kato
authors.forename: A G
authors.initials: AG
authors.lastname: Fraser
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002339:Carotid Arteries / Q000502:physiology; D004548:Elasticity; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012044:Regression Analysis; D012737:Sex Factors; D018084:Ultrasonography, Interventional / Q000379:methods*