A non-invasive clinical application of wave intensity analysis based on ultrahigh temporal resolution phase-contrast cardiovascular magnetic resonance

Biglino, Giovanni; Steeden, Jennifer A.; Baker, Catriona; Schievano, Silvia; Taylor, Andrew M.; Parker, Kim H.; Muthurangu, Vivek

doi:10.1186/1532-429x-14-57

Cited by 49 publications

(57 citation statements)

References 22 publications

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“…Biglino et al performed wave intensity analysis using CMR in the ascending and descending aorta in healthy controls, patients with coronary heart disease [9] and congenital heart disease [28]. They demonstrated that wave intensity in the aorta was feasible using phase contrast CMR, with temporal wave intensity profiles that were in keeping with previously demonstrated invasive profiles, however they did not compare the technique with invasive data.…”

Section: Discussionmentioning

confidence: 99%

“…WIA has recently been successfully performed using CMR in the ascending and descending aorta [9], however it has never been attempted in the highly-mobile, small-caliber, tortuous coronary arteries, nor has it been directly compared to invasively acquired data. Accordingly, we assessed the feasibility of coronary WIA using CMR and compared to invasive measures in the same patients.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility of cardiovascular magnetic resonance derived coronary wave intensity analysis

Raphael

Keegan

Parker

et al. 2016

Journal of Cardiovascular Magnetic Resonance

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BackgroundWave intensity analysis (WIA) of the coronary arteries allows description of the predominant mechanisms influencing coronary flow over the cardiac cycle. The data are traditionally derived from pressure and velocity changes measured invasively in the coronary artery. Cardiovascular magnetic resonance (CMR) allows measurement of coronary velocities using phase velocity mapping and derivation of central aortic pressure from aortic distension. We assessed the feasibility of WIA of the coronary arteries using CMR and compared this to invasive data.MethodsCMR scans were undertaken in a serial cohort of patients who had undergone invasive WIA. Velocity maps were acquired in the proximal left anterior descending and proximal right coronary artery using a retrospectively-gated breath-hold spiral phase velocity mapping sequence with high temporal resolution (19 ms). A breath-hold segmented gradient echo sequence was used to acquire through-plane cross sectional area changes in the proximal ascending aorta which were used as a surrogate of an aortic pressure waveform after calibration with brachial blood pressure measured with a sphygmomanometer. CMR-derived aortic pressures and CMR-measured velocities were used to derive wave intensity. The CMR-derived wave intensities were compared to invasive data in 12 coronary arteries (8 left, 4 right). Waves were presented as absolute values and as a % of total wave intensity. Intra-study reproducibility of invasive and non-invasive WIA was assessed using Bland-Altman analysis and the intraclass correlation coefficient (ICC).ResultsThe combination of the CMR-derived pressure and velocity data produced the expected pattern of forward and backward compression and expansion waves. The intra-study reproducibility of the CMR derived wave intensities as a % of the total wave intensity (mean ± standard deviation of differences) was 0.0 ± 6.8%, ICC = 0.91. Intra-study reproducibility for the corresponding invasive data was 0.0 ± 4.4%, ICC = 0.96. The invasive and CMR studies showed reasonable correlation (r = 0.73) with a mean difference of 0.0 ± 11.5%.ConclusionThis proof of concept study demonstrated that CMR may be used to perform coronary WIA non-invasively with reasonable reproducibility compared to invasive WIA. The technique potentially allows WIA to be performed in a wider range of patients and pathologies than those who can be studied invasively.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-016-0312-8) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Feasibility of cardiovascular magnetic resonance derived coronary wave intensity analysis

Raphael

Keegan

Parker

et al. 2016

Journal of Cardiovascular Magnetic Resonance

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“…used tool for analyzing hemodynamics in the time domain (2,6,12,13,15,22,34,39,43,47). More recently, three alternative definitions of wave intensity have been proposed.…”

Section: Discussionmentioning

confidence: 99%

“…More recently, three alternative definitions of wave intensity have been proposed. For settings where noninvasive measurements of blood velocity and vessel diameter (D) or vessel area (A) are available (e.g., echocardiography and phase contrast MRI), Feng and Khir (9) proposed the use of dDdU, Tanaka et al (42) advocated d[lnD]dU, while Biglino et al (2) used d[lnA]dU. Although similar to wave intensity, these quantities have units of m 2 /s, m/s, and m/s, respectively, whose physical meaning is unclear in this context (the term "wave intensity" was retained, even though the units were no longer those of intensity).…”

Section: Discussionmentioning

confidence: 99%

Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power

Mynard

Smolich

2016

American Journal of Physiology-Heart and Circulatory Physiology

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Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward wave-related components (ΠP±and ΠQ±). Wave power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics.

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“…This has been done because no major viscous effects were expected in the current setting and because the study was focusing on the feasibility of the setup and pulmonary measurements. A commonly used blood analogue is a solution of water and glycerine with a volume percentage of 33.5% glycerine [2,5,29], which could be easily employed in this setting.The RPA-LPA flow distribution, governed by the downstream resistances, was similar to the normal in vivo flow distribution of 55-45% [30] and the RPA/LPA ratio of 1.18 corresponds to a ratio of 1.1 ± 0.2 for the adult human pulmonary circulation at rest [31]. The pressure for the IPVR scenario (33.8 ± 0.2 mm Hg) was within the range of PAH and was significantly higher than the pressure for the healthy scenario.…”

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confidence: 99%

A Mock Circulatory System Incorporating a Compliant 3D‐Printed Anatomical Model to Investigate Pulmonary Hemodynamics

Knoops

Biglino

Hughes³

et al. 2016

Artificial Organs

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A realistic mock circulatory system (MCS) could be a valuable in vitro testbed to study human circulatory hemodynamics. The objective of this study was to design a MCS replicating the pulmonary arterial circulation, incorporating an anatomically representative arterial model suitable for testing clinically relevant scenarios. A second objective of the study was to ensure the system's compatibility with magnetic resonance imaging (MRI) for additional measurements. A latex pulmonary arterial model with two generations of bifurcations was manufactured starting from a 3D-printed mold reconstructed from patient data. The model was incorporated into a MCS for in vitro hydrodynamic measurements. The setup was tested under physiological pulsatile flow conditions and results were evaluated using wave intensity analysis (WIA) to investigate waves traveling in the arterial system. Increased pulmonary vascular resistance (IPVR) was simulated as an example of one pathological scenario. Flow split between right and left pulmonary artery was found to be realistic (54 and 46%, respectively). No substantial difference in pressure waveform was observed throughout the various generations of bifurcations. Based on WIA, three main waves were identified in the main pulmonary artery (MPA), that is, forward compression wave, backward compression wave, and forward expansion wave. For IPVR, a rise in mean pressure was recorded in the MPA, within the clinical range of pulmonary arterial hypertension. The feasibility of using the MCS in the MRI scanner was demonstrated with the MCS running 2 h consecutively while Address correspondence and reprint requests to: Paul Knoops, 30 Guilford Street, London WC1N 1EH, UK. paul.knoops. 14@ucl.ac.uk. Author ContributionsConception and design of the work: PGMK, GB, ADH, SS, RT; experimental setup, data acquisition and analysis: PGMK, GB, LX; interpretation of the data: PGMK, GB, ADH, KHP, RT; drafting the manuscript: PGMK, GB, RT; all authors critically revised the manuscript, read and approved the final manuscript. Conflict of InterestThe authors declare no conflict of interest. Europe PMC Funders GroupAuthor Manuscript Artif Organs. Author manuscript; available in PMC 2017 July 15. Published in final edited form as:Artif Organs. 2017 July ; 41(7): 637-646. doi:10.1111/aor.12809. Europe PMC Funders Author ManuscriptsEurope PMC Funders Author Manuscripts acquiring preliminary MRI data. This study shows the development and verification of a pulmonary MCS, including an anatomically correct, compliant latex phantom. The setup can be useful to explore a wide range of hemodynamic questions, including the development of patientand pathology-specific models, considering the ease and low cost of producing rapid prototyping molds, and the versatility of the setup for invasive and noninvasive (i.e., MRI) measurements.Mock circulatory systems (MCS) are widely used to gather hydrodynamic data in vitro. They allow investigation of the cardiovascular system in both healthy and pathological scenarios, with t...

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A non-invasive clinical application of wave intensity analysis based on ultrahigh temporal resolution phase-contrast cardiovascular magnetic resonance

Cited by 49 publications

References 22 publications

Feasibility of cardiovascular magnetic resonance derived coronary wave intensity analysis

Feasibility of cardiovascular magnetic resonance derived coronary wave intensity analysis

Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power

A Mock Circulatory System Incorporating a Compliant 3D‐Printed Anatomical Model to Investigate Pulmonary Hemodynamics

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