liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
On cardiac flow quantification with ultrasound colour doppler
Linköping University, Department of Biomedical Engineering. Linköping University, Department of Medicine and Care, Clinical Physiology. Linköping University, Department of Mechanical Engineering. Linköping University, Faculty of Health Sciences.
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with the estimation of blood flow in the heart and larger vessels where control-volume methods are applied using ultrasound Doppler technique. In particular two control-volume techniques were investigated: The proximal isovelocity surface area method, (PISA) and the Surface Integration of Velocity Vectors method, (SIVV).

For PISA, computational fluid dynamics, (CFD) was used for non-stationary flow and non-planar circular geometries where special emphasis was given to the influence from the angle of the valvular leaflets on the proximal surface area. The CFD results were compared with ultrasound measurements, in an in-vitro model with controlled geometry and flow characteristics. Three different valvular geometries were used: planar, reversed cone and funnel. In these idealised CFD and experimental models it was found that there is support to use the hemispherical PISA approach for the geometries investigated provided that the flow is not to high in the reversed cone and funnel case. At high flows the actual proximal geometry should be used instead of an entire hemisphere.

A hydraulic pulsatile model was used in developing a platform with in-house software where the SIVV flows automatically may be calculated from a digitally stored raw data. An antialiasing algorithm was developed to allow for measurement of aliased data in order to increase the dynamic velocity range. The antialiasing algorithm was found to improve the estimation of SIVV flow.

The influence on the flow estimate was investigated with respect to the number of scan-planes using a numerical model and in-vitro and in-vivo model experiments. It was found that a minimum of two scan-planes are needed when flow conditions and geometry is close to circular, otherwise the recommendation is four scan-planes.

A steady state and a pulsatile model was used to evaluate accuracy of the SIVV method more extensively in vitro. SIVV was found to be accurate and repeatable with a slight underestimation in the pulsatile model but within the ±10% range. In the steady state model a strong correlation was found between SIVV and timed flow. However, since discrepancies in regression equations were obtained for different tube diameters further investigation of steady state flows in vessels of small diameter are needed.

An in-vivo model was designed to study the possibility to use the SIVV method to measure cardiac output in a paediatric model in haemodynamically unstable subjects and to investigate what measurement site to use. Epicardial measurements were performed on a series of piglets using two different temporal resolutions. SJVV accuracy was compared with ultrasound transit time flow and was found to be in parity or better than current invasive methods. Inter- and lntraobserver variability was found to be low.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2000. , 48 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 625
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-29447Local ID: 14794ISBN: 91-7219-702-1 (print)OAI: oai:DiVA.org:liu-29447DiVA: diva2:250262
Public defence
2000-04-17, Berzeliussalen, Universitetssjukhuset, Linköping, 09:15 (Swedish)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-02-25
List of papers
1. Non-stationary flow through non-planar circular constrictions: application to mitral valve disease
Open this publication in new window or tab >>Non-stationary flow through non-planar circular constrictions: application to mitral valve disease
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Quantification of valvular malfunctions by means of noninvasive methods is presently far from perfect. Since valvular regurgitation is common, a simple and reliable method for quantitative assessment is desired. In this paper the proximal isovelocity surface area method, (PISA) was studied. Numerical simulations for non-stationary flow and non-planar circular geometries were compared with ultrasound measurements in an invitro model with the same geometry and similar flow characteristics. Three different valvular geometries were used: planar, reversed cone and funnel. In the numerical simulation special emphasis was given to the influence from the angle of the valvular leaflets on the proximal surface area. We found both numerically and experimentally that there is support to use the hemispherical velocity profile assumption for the geometries investigated except for the funnel case. Here the actual geometry at the funnel inlet should be considered instead of the half-sphere approximation.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-89303 (URN)
Available from: 2013-02-25 Created: 2013-02-25 Last updated: 2016-03-14
2. Increased accuracy of echocardiographic measurement of flow using automated spherical integration of multiple plane velocity vectors
Open this publication in new window or tab >>Increased accuracy of echocardiographic measurement of flow using automated spherical integration of multiple plane velocity vectors
1999 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 25, no 2, 249-257 p.Article in journal (Refereed) Published
Abstract [en]

The calculation of blood flow in the heart by surface integration of velocity vectors (SIVV) using Doppler ultrasound is independent of the angle. Flow is normally calculated from velocity in a spherical thick shell with its center located at the ultrasound transducer. In a numerical simulation, we have shown that the ratio between minor and major axes of an elliptic flow area substantially influences the accuracy of the estimation of flow in a single scan plane. The accuracy of flow measurements by SIVV can be improved by calculating the mean of the values from more than one scan plane. We have produced an automated computer program that includes an antialiasing procedure. We confirmed an improvement of flow measurements in a pulsatile hydraulic flow model, the 95% confidence interval for single estimations being reduced from 20% to 10% (p < 0.05) using the newly developed software. We think that the SIVV method has important implications for clinical transthoracic echocardiography.

National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-67263 (URN)10.1016/S0301-5629(98)00159-8 (DOI)10320314 (PubMedID)
Available from: 2011-04-06 Created: 2011-04-06 Last updated: 2017-12-11
3. How many planes are necessary for accurate cardiac output measurement using surface integration of velocity vectors (SIVV) in the left ventricular outflow tract? Pediatric application
Open this publication in new window or tab >>How many planes are necessary for accurate cardiac output measurement using surface integration of velocity vectors (SIVV) in the left ventricular outflow tract? Pediatric application
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Flow measurements with surface integration of velocity vectors, (SIVV) is a three dimensional approach where velocities measured by colour Doppler from several two-dimensional imaging planes are gathered and flow is automatically calculated. With SIVV no assumptions regarding the Doppler insonation angle, area changes and flow profile are necessary, thus avoiding such errors. Numerical simulations have shown that an elliptic area less than 1:2 in major minor axis relation needs at least two equidistant (preferably four) planes for accurate measurements. The purpose of this study was to evaluate this finding in a controlled in vitro environment and in high quality in vivo observations. A Plexiglass® pulsatile flow model was used where the outflow tract allows for insertion of an artificial valve. A total of 12 images were acquired with an increment of 15o at three flow rates (0.9- 3.0 1/min). A series of piglets (13.5-17 kg) were stemotomized, and a 5MHz phased array transthoracic probe placed at the apex with the beam directed towards the left ventricular outflow tract, (LVOT) simulating the transoesophageal transgastric or transthoracic apical view. Epicardial images were acquired in 4 planes (45o increments). Ten high quality sequences at different cardiac output levels (0.9 - 2.1 1/min) were selected and compared to ultrasound transit time (TT) cardiac output measurement. The results show that for the in-vitro case, at least two planes were necessary for measurements with an error of <10%. In-vivo, four planes were required for errors of <20%. Our study confirms the theoretical assumption that at least two planes are preferable to obtain accurate flow measurements from colour Doppler data.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-89306 (URN)
Available from: 2013-02-25 Created: 2013-02-25 Last updated: 2013-02-25
4. Doppler flow measurement using surface integration of velocity vectors (Sivv): in vitro validation
Open this publication in new window or tab >>Doppler flow measurement using surface integration of velocity vectors (Sivv): in vitro validation
Show others...
2000 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 26, no 2, 255-262 p.Article in journal (Refereed) Published
Abstract [en]

Blood flow measurement using an improved surface integration of velocity vectors (SIVV) technique was tested in in vitro phantoms. SIVV was compared with true flow (12–116 mL/s) in a steady-state model using two angles of insonation (45° and 60°) and two vessel sizes (internal diameter = 11 and 19 mm). Repeatability of the method was tested at various flow rates for each angle of insonation and vessel. In a univentricular pulsatile model, SIVV flow measured at the mitral inlet was compared to true flow (29–61 mL/s). Correlation was excellent for the 19-mm vessel (r2= 0.99). There was a systematic bias but close limits of agreement (mean ± 2 SD = −24.1% ± 7.6% at 45 °; +16.4% ± 11.0% at 60 °). Using the 11-mm vessel, a quadratic relationship was demonstrated between between SIVV and true flow (r2 = 0.98–0.99), regardless of the angle of insonation. In the pulsatile system, good agreement and correlation were shown (r2 = 0.94, mean ± 2 SD = −4.7 ± 10.1%). The coefficients of variation for repeated SIVV measurements ranged from 0.9% to 10.3%. This method demonstrates precision and repeatability, and is potentially useful for clinical measurements.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-29740 (URN)10.1016/S0301-5629(99)00136-2 (DOI)15139 (Local ID)15139 (Archive number)15139 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13
5. Pediatric cardiac output measurement using surface integration of velocity vectors: an in vivo validation study
Open this publication in new window or tab >>Pediatric cardiac output measurement using surface integration of velocity vectors: an in vivo validation study
Show others...
2000 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 28, no 11, 3664-3671 p.Article in journal (Refereed) Published
Abstract [en]

Objective: To test the accuracy and reproducibility of systemic cardiac output (CO) measurements using surface integration of velocity vectors (SIVV) in a pediatric animal model with hemodynamic instability and to compare SIVV with traditional pulsed-wave Doppler measurements.

Design: Prospective, comparative study.

Setting: Animal research laboratory at a university medical center.

Subjects: Eight piglets weighing 10-15 kg.

Interventions: Hemodynamic instability was induced by using inhalation of isoflurane and infusions of colloid and dobutamine.

Measurements: SIVV CO was measured at the left ventricular outflow tract, the aortic valve, and ascending aorta. Transit time CO was used as the reference standard.

Results: There was good agreement between SIVV and transit time CO. At high frame rates, the mean difference ± 2 sd between the two methods was 0.01 ± 0.27 L/min for measurements at the left ventricular outflow tract, 0.08 ± 0.26 L/min for the ascending aorta, and 0.06 ± 0.25 L/min for the aortic valve. At low frame rates, measurements were 0.06 ± 0.25, 0.19 ± 0.32, and 0.14 ± 0.30 L/min for the left ventricular outflow tract, ascending aorta, and aortic valve, respectively. There were no differences between the three sites at high frame rates. Agreement between pulsed-wave Doppler and transit time CO was poorer, with a mean difference ± 2 sd of 0.09 ± 0.93 L/min. Repeated SIVV measurements taken at a period of relative hemodynamic stability differed by a mean difference ±2 sd of 0.01 ± 0.22 L/min, with a coefficient of variation = 7.6%. Intraobserver coefficients of variation were 5.7%, 4.9%, and 4.1% at the left ventricular outflow tract, ascending aorta, and aortic valve, respectively. Interobserver variability was also small, with a coefficient of variation = 8.5%.

Conclusions: SIVV is an accurate and reproducible flow measurement technique. It is a considerable improvement over currently used methods and is applicable to pediatric critical care.

National Category
Medical Laboratory and Measurements Technologies
Identifiers
urn:nbn:se:liu:diva-62969 (URN)11098971 (PubMedID)
Available from: 2010-12-08 Created: 2010-12-08 Last updated: 2017-12-11

Open Access in DiVA

No full text

By organisation
Department of Biomedical EngineeringClinical PhysiologyDepartment of Mechanical EngineeringFaculty of Health Sciences
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 357 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf