A transmission line modelling approach to the interpretation of uterine doppler waveforms

Mo, L.Y.L.; Bascom, P.A.J.; Ritchie, Knox; McCowan, Lesley

doi:10.1016/0301-5629(88)90072-5

Cited by 65 publications

(54 citation statements)

References 18 publications

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“…1). Following Mo et al [27], the artery connecting a and b will be modelled by a uniform electrical transmission line characterized by its specific resistance (viscosity) and capacitance (compliance). Blood inertia modelled as an inductance L has been shown to be negligible in this case [25,26], The part o f the vascular tree descending from b will be represented by an equivalent impedance Zl the value of which will be determined from a principle verified in various other arterial systems [30], according to which arterial systems are general ly growing with matched impedances so that wave reflections at the branchings are minimal.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…The classi cal lumped circuit model by Thompson and Stevens [25] and Thompson and Trudinger [26] is too simplistic to describe the pressure and pulsatility gradients down the vascular tree. A more sophisticated model, similar to the transmission line approach by Mo et al [27], will be pre sented. The model is general and is mainly based on the assumption that in the normal placenta impedances are matched so that there*are no wave reflections.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A New Technique for Improved Diagnosis of Local Placental Abnormalities: Fourier Analysis of Intraplacental Waveforms

Haberman

Friedman²

1993

Gynecol Obstet Invest

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A new method to diagnose localized placental lesions is introduced. The method involves Fourier analysis of intraplacental and umbilical Doppler velocity waveforms. It is shown, using a theoretical model based on an electrical transmission line approach, that intraplacental waveforms that are of higher pulsatilities than those in the umbilical artery indicate placental abnormalities. The method was applied in a series of cases with normal umbilical waveforms in which placental abnormalities were diagnosed. The method promises to be more sensitive and specific than analyzing umbilical waveforms alone as it does not depend on uncertain threshold values.

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Section: Theoretical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A New Technique for Improved Diagnosis of Local Placental Abnormalities: Fourier Analysis of Intraplacental Waveforms

Haberman

Friedman²

1993

Gynecol Obstet Invest

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“…The 'notch' is then considered to represent a reflected wave re turning from a high vascular resistance utero placental bed [12].…”

Section: Discussionmentioning

confidence: 99%

Are ‘Notched’ Uterine Arterial Waveforms of Prognostic Value for Hypertensive and Growth Disorders of Pregnancy?

Mires

Christie²,

Leslie³

et al. 1995

Fetal Diagn Ther

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In a case-control controlled study of 86 women identified as having bilaterally ‘notched’ uterine arterial waveform patterns at 18 weeks, the presence of bilateral ‘notched’ uterine arterial waveforms at that time was associated with the subsequent development of hypertension and small-for-gestational-age infants, but the predictive value was poor. For those women in whom the bilateral uterine ‘notches’ were observed to persist to 24 weeks, the relative risk of developing proteinuric hypertension increased 14 times, and in these women the positive predictive value for the subsequent development of hypertension increased to 58.6% when compared with their matched controls. The identification of women with persistent bilateral uterine ‘notches’ provides a means of identifying women at significant risk of hypertensive and growth disorders at a stage when therapeutic intervention aimed at limiting the severity of the disease and its associated complications could be commenced.

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“…Although qualitative velocity indices have proved to be meaningful parameters for assessing utero-and fetoplacental vascular impedance [ 1 ], they do not cover every aspect of the flow waveform. Thus, early diastolic uteroplacental waveform notching, denoting increased vascular resistance [2] and often ob served in pregnancies at risk through intrauterine growth retardation and/or pregnancy-induced hypertension, is insufficiently or not at all represented when using the RI or PI indices for waveform evaluation. We therefore attempted to describe the flow velocity wave form by way of a mathematical model which resolves the waveform into orthogonal polynomial components including 111°.…”

Section: Introductionmentioning

confidence: 99%

Polynomial Analysis of Placental Flow Patterns in Growth-Retarded Fetuses

Hütter¹,

Grab

Sterzik

et al. 1993

Gynecol Obstet Invest

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Correct interpretation of conspicuous blood flow velocity waveforms cannot rely solely on the evaluation of uteroplacental vascular Doppler flow patterns by means of angle-independent indices such as the resistance or pulsatility index. In addition to the degree of pulsatility, the waveform shape between the systolic and diastolic peak values is of considerable consequence. A subdivision of the total flow waveform into orthogonal polynomial components allows both pulsatility evaluation and notching to be registered, providing a higher sensitivity in identification of pathological vascular resistance. Accurate recording and assessment of the flow waveform is therefore an important qualitative criterion for the classification of Doppler flow patterns in pregnancies with reduced uteroplacental perfusion.

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A transmission line modelling approach to the interpretation of uterine doppler waveforms

Cited by 65 publications

References 18 publications

A New Technique for Improved Diagnosis of Local Placental Abnormalities: Fourier Analysis of Intraplacental Waveforms

A New Technique for Improved Diagnosis of Local Placental Abnormalities: Fourier Analysis of Intraplacental Waveforms

Are ‘Notched’ Uterine Arterial Waveforms of Prognostic Value for Hypertensive and Growth Disorders of Pregnancy?

Polynomial Analysis of Placental Flow Patterns in Growth-Retarded Fetuses

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