Use of simultaneous pressure and velocity measurements to estimate arterial wave speed at a single site in humans

Davies, Justin E.; Whinnett, Zachary I.; Francis, Dárrel P.; Willson, Keith; Foale, Rodney A.; Malik, Iqbal; Hughes, Alun D.; Parker, Kim H.; Mayet, Jamil

doi:10.1152/ajpheart.00751.2005

Cited by 133 publications

(132 citation statements)

References 31 publications

(40 reference statements)

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“…While the AO-PWV1 is the regional PWV of the ascending aorta, the AO-PWV2 reflects the mean PWV of 2 points between the ascending and thoracic aorta, so their values are naturally expected to differ. According to previous studies, the normal AO-PWV2 in middle-aged people is about 5-8 m/s, [19][20][21][22] being close to the mean AO-PWV1 and AO-PWV2 values observed in this study. Comparison of the regional PWV values in the human aorta showed that the values increase at more peripheral sites.…”

Section: Discussionsupporting

confidence: 89%

Validity of the Water Hammer Formula for Determining Regional Aortic Pulse Wave Velocity: Comparison of One-Point and Two-Point (Foot-to-Foot) Measurements Using a Multisensor Catheter in Human

Hanya

2013

Annals of Vascular Diseases

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Background: Lack of high-fidelity simultaneous measurements of pressure and flow velocity in the aorta has impeded the direct validation of the water-hammer formula for estimating regional aortic pulse wave velocity (AO-PWV1) and has restricted the study of the change of beat-to-beat AO-PWV1 under varying physiological conditions in man. Methods: Aortic pulse wave velocity was derived using two methods in 15 normotensive subjects: 1) the conventional two-point (foot-to-foot) method (AO-PWV2) and 2) a one-point method (AO-PWV1) in which the pressure velocity-loop (PV-loop) was analyzed based on the water hammer formula using simultaneous measurements of flow velocity (Vm) and pressure (Pm) at the same site in the proximal aorta using a multisensor catheter. AO-PWV1 was calculated from the slope of the linear regression line between Pm and Vm where wave reflection (Pb) was at a minimum in early systole in the PV-loop using the water hammer formula, PWV1 = (Pm/Vm)/r, where r is the blood density. AO-PWV2 was calculated using the conventional two-point measurement method as the distance/traveling time of the wave between 2 sites for measuring P in the proximal aorta. Beat-to-beat alterations of AO-PWV1 in relationship to aortic pressure and linearity of the initial part of the PV-loop during a Valsalva maneuver were also assessed in one subject. Keywords: multisensor catheter, water-hammer formula, regional pulse wave velocity of the proximal aorta, aortic elasticity, aortic wave reflection

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Section: Discussionsupporting

confidence: 89%

Validity of the Water Hammer Formula for Determining Regional Aortic Pulse Wave Velocity: Comparison of One-Point and Two-Point (Foot-to-Foot) Measurements Using a Multisensor Catheter in Human

Hanya

2013

Annals of Vascular Diseases

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“…Pulse wave velocity was estimated using the single point method described by Davies et al 17 This produces the same waveform separation as an analysis in the frequency domain.…”

Section: Waveform Post Processingmentioning

confidence: 99%

“…Pulse wave velocity was estimated using the single point method described by Davies et al 17 This produces the same waveform separation as an analysis in the frequency domain. 18 Aortic flow velocity waveforms were integrated over time and multiplied by aortic cross-sectional area …”

Section: Waveform Post Processingmentioning

confidence: 99%

Augmentation Pressure Is Influenced by Ventricular Contractility/Relaxation Dynamics

Fok

Guilcher

et al. 2014

Hypertension

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A ortic or central pulse pressure (cPP) determines the pulsatile load on the left ventricle, coronary, and carotid arteries and is a major risk factor for adverse cardiovascular events, with at least as strong a relation to such events as peripheral pulse pressure.1-3 cPP is widely assumed to be determined by the interaction of an outgoing forward pressure wave (FPW) generated by ventricular contraction and a backward going pressure wave (BPW) generated by reflections from the periphery of the circulation. 4,5 These components of cPP are separated by the first systolic shoulder of the aortic pulse ( Figure 1). The height of this above diastolic blood pressure (P1) is attributed to the FPW and the height above P1, the augmentation pressure (AP), to the BPW. 6 Augmentation index (AIx), the ratio of AP to cPP, is widely used as a measure of pressure wave reflection. This interpretation has, however, been criticized because of the poor relationship between the magnitude and timing of reflected waves with respect to AP. 7,8 Nitroglycerin (NTG) has a particularly marked action to reduce AP and hence cPP attributed to a change in timing or amplitude of pressure wave reflections. [9][10][11] However, an alternative explanation relates to an influence of nitrovasodilators on contraction-relaxation dynamics of the myocardium, effects observed in isolated myocytes and in vivo. 12,13The aim of the present study was to determine the mechanism by which AP is selectively reduced by NTG. We made simultaneous measurements of aortic pressure and flow and used wave intensity analysis to separate pressure waves into FPW and BPW components.14 Pressure waves were further categorized as compression or expansion (suction). A primary forward compression wave (FCW) arises from the push of the ventricle against the arterial tree and a systolic backward compression wave (BCW) from the push of the arterial tree against the ventricle. A late systolic forward expansion wave (FEW) arises from the braking effect of the ventricle in late systole. 15 These measurements together with cardiac output and the impedance of the arterial tree were obtained at baseline and after systemic administration of NTG. To further distinguish between effects of NTG related to an action on the myocardium and arterial tree, we examined effects of intracoronary infusion of NTG at a dose below the threshold required to produce systemic effects.Abstract-Augmentation pressure (AP), the increment in aortic pressure above its first systolic shoulder, is thought to be determined mainly by pressure wave reflection but could be influenced by ventricular ejection characteristics. We sought to determine the mechanism by which AP is selectively reduced by nitroglycerin (NTG). Simultaneous measurements of aortic pressure and flow were made at the time of cardiac catheterization in 30 subjects (11 women; age, 61±13 years [mean±SD]) to perform wave intensity analysis and calculate forward and backward components of AP generated by the ventricle and arterial tree, respectively. ...

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“…Several different methods of obtaining regional pulse wave velocity, c, in an artery have been reported by Khir et al [16,17], Davies et al [6], and ourselves [10]. Our wave intensity measurement system uses the two methods proposed by ourselves.…”

Section: Separation Of Wave Intensity Into the Forward And Backward Cmentioning

confidence: 99%

Clinical usefulness of wave intensity analysis

Sugawara

Niki

Ohte

et al. 2008

Med Biol Eng Comput

104

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Wave intensity (WI) is a hemodynamic index, which can evaluate the working condition of the heart interacting with the arterial system. It can be defined at any site in the circulatory system and provides a great deal of information. However, we need simultaneous measurements of blood pressure and velocity to obtain wave intensity, which has limited the clinical application of wave intensity, in spite of its potential. To expand the application of wave intensity in the clinical setting, we developed a real-time non-invasive measurement system for wave intensity based on a combined color Doppler and echo-tracking system. We measured carotid arterial WI in normal subjects and patients with various cardiovascular diseases. In the coronary artery disease group, the magnitude of the first peak of carotid arterial WI (W 1 ) increased with LV max. dP/dt (r = 0.74, P \ 0.001), and the amplitude of the second peak (W 2 ) decreased with an increase in the time constant of LV pressure decay (r = -0.77, P \ 0.001). In the dilated cardiomyopathy group, the values of W 1 were much lower than those in the normal group (P \ 0.0001). In the hypertrophic cardiomyopathy group, the values of W 2 were much smaller than those in the normal group (P \ 0.0001). In mitral regurgitation before surgery, W 2 decreased or disappeared, but after surgery W 2 appeared clearly. In the hypertension group, the magnitude of reflection from the head was considerably greater than that in the normal group (P \ 0.0001). We also evaluated hemodynamic effects of sublingual nitroglycerin in normal subjects. Nitroglycerin increased W 1 significantly (P \ 0.001). WI can be obtained non-invasively using an echo-Doppler system in the clinical setting. This method will increase the clinical usefulness of wave intensity.

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Use of simultaneous pressure and velocity measurements to estimate arterial wave speed at a single site in humans

Cited by 133 publications

References 31 publications

Validity of the Water Hammer Formula for Determining Regional Aortic Pulse Wave Velocity: Comparison of One-Point and Two-Point (Foot-to-Foot) Measurements Using a Multisensor Catheter in Human

Validity of the Water Hammer Formula for Determining Regional Aortic Pulse Wave Velocity: Comparison of One-Point and Two-Point (Foot-to-Foot) Measurements Using a Multisensor Catheter in Human

Augmentation Pressure Is Influenced by Ventricular Contractility/Relaxation Dynamics

Clinical usefulness of wave intensity analysis

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