No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Quantitative measurements of celeration times and indexes in the ductus venosus spectral Doppler waveforms in normal fetuses
Abstract
Background
Ductus venosus spectral waveform has two peaks and two nadirs: S, v, D and a velocities, which are obtained after to some extent of accelerations or decelerations throughout a cardiac cycle. It is aimed to define the actual celeration times and indexes and their relationships with the fetal heart rate (FHR).
Methods
The acceleration times and indexes were measured in 357 patients between 11 and 40 weeks of pregnancies with low risk.
Results
The FHR has a gradual increasing negative correlation from time for S to time for a with each of the cardiac times of phases according to the statistical analysis (correlations were minus 190, 269, 407 and 541 for S, v, D and a phase times, respectively). The acceleration aS and the deceleration Da have positive correlations with the FHR; however, the deceleration Sv and the acceleration vD do not correlate with the FHR.
Conclusion
The deceleration Da time and index are the main components for determining the FHR in fetuses. Therefore, the atrial contraction is the strongest component for determining the FHR in fetuses.
ResearchGate has not been able to resolve any citations for this publication.
Purpose:
The aim of this study was to investigate factors that influence arterial Doppler waveforms in an in vitro phantom to provide a more accurate and comprehensive explanation of the Doppler signal.
Methods:
A flow model was created using a pulsatile artificial heart, rubber or polyethylene tubes, a water tank, and a glass tube. Spectral Doppler tracings were obtained in multiple combinations of compliance, resistance, and pulse rate. Peak systolic velocity, minimum diastolic velocity, resistive index (RI), pulsatility index, early systolic acceleration time, and acceleration index were measured. On the basis of these measurements, the influences of the variables on the Doppler waveforms were analyzed.
Results:
With increasing distal resistance, the RI increased in a relatively linear relationship. With increasing proximal resistance, the RI decreased. The pulsus tardus and parvus phenomenon was observed with a small acceleration index in the model with a higher grade of stenosis. An increase in the distal resistance masked the pulsus tardus and parvus phenomenon by increasing the acceleration index. Although this phenomenon occurred independently of compliance, changes in the compliance of proximal or distal tubes caused significant changes in the Doppler waveform. There was a reverse relationship between the RI and the pulse rate.
Conclusion:
Resistance and compliance can alter the Doppler waveforms independently. The pulse rate is an extrinsic factor that also influences the RI. The compliance and distal resistance, as well as proximal resistance, influence the pulsus tardus and parvus phenomenon.
The ductus venosus has a central role in the distribution of highly oxygenated umbilical venous blood to the heart. Its waveform is related to the pressure-volume changes in the cardiac atria, and therefore, it is important in the monitoring of any fetal condition that may affect forward cardiac function. The cardiovascular parameters that can influence forward cardiac function include afterload, myocardial performance and preload. Decreased forward flow during atrial systole (a-wave) is the most sensitive and ubiquitous finding when any of these parameters is affected. In contrast, decreased forward velocities during end-systolic relaxation (v-wave) are more specifically related to myocardial performance. The ductus venosus pulsatility index alone does not accurately reflect cardiac function, and in cases of suspected fetal cardiac dysfunction, echocardiography is required to identify the underlying mechanism. The role of ductus venosus Doppler in the assessment of fetal growth restriction, supraventricular tachycardia, fetal hydrops, complicated monochorionic twins and congenital heart disease is discussed with these considerations in mind. This article is protected by copyright. All rights reserved.
The purpose of this review is to evaluate the current modalities available for the assessment of fetal cardiac function. The unique anatomy and physiology of the fetal circulation are described, with reference to the difference between in-utero and ex-utero life. M-mode, early/atrial ratio, myocardial performance index, three-dimensional and four-dimensional ultrasound, tissue Doppler including strain and strain rate, speckle tracking, magnetic resonance imaging and venous flow assessment are described. The modalities are analyzed from the perspective of the clinician and certain questions are posed. Does the modality assess systolic function, diastolic function or both? Is it applicable to both ventricles? Does it require extensive post-processing or additional hardware, or does it make use of technology already available to the average practitioner? The reproducibility and reliability of the techniques are evaluated, with reference to their utility in clinical decision-making. Finally, directions for future research are proposed.
Objectives: Ductus venosus (DV) Doppler examinations in pregnancy have a widespread use for several important indications and play a crucial role in order to determine the fetal well-being. DV is usually visualized by the color Doppler mapping. We observed the instantaneous spectral flow type changes in pulsed Doppler examinations in spite of performing with the correct technique published by several authors. The variability of the pattern makes the sonographer/physician to be unsure for the correct placements of the sample gate despite fulfilling the all the criteria required for the vessel sampling. It is aimed in the study to define variations of the normal DV spectral flow types in the duration of the pulsed Doppler examinations instead of in a single cardiac cycle in normal pregnancies.
Methods: This prospective study was conducted between January 2016 and February 2017. Wide-band Doppler technique was used for color mapping of the DV. Normal spectral Doppler waveforms in pregnancies are classified as types. When DV spectral flow pattern was not in the standard type, the spectral flow patterns were obtained from not only the umbilical artery and/or middle cerebral artery. Maximum and minimum blood flow velocities in the umbilical vein are measured. All Doppler examinations are performed by a single experienced specialist (CG), who had been certificated for DV flow and Doppler examinations by Fetal Medicine Foundation.
Results: A total of seven types of flow patterns were recorded during the study period and DV flow patterns were divided into two main categories as classic flow pattern and the other patterns. The classic pattern was observed in 160 (99.4%) cases in the first trimester, 495 (94.1%) cases in the second trimester and 206 (60.8%) cases in the third trimester.
Conclusions: We think that the fetal circulation is complicated more than estimated. There might be some endocrine agents released in the instantaneous physiologic reactions and changing the venous return abruptly or due to decreasing of the cardiac output directed to the placenta after 34 weeks influence the volume of the circulating blood in the fetus and so thereby the flow velocities instantaneously. The spectral waveform recognition approach is not reliable to identify if the DV spectral Doppler pattern is not the classic (standard) type and the DV should be visualized by wide-band color Doppler techniques particularly in the third trimester for the pulsed Doppler examinations. Studies are needed to evaluate the normal spectral variants of the flows correlated with the physiological compensatory mechanisms.
Interpretation of venous waveform patterns is complex as the multiphasic waveforms reflect events in the cardiac cycle that may be differentially affected by clinical pathology. We sought to identify the range of waveform abnormalities in the ductus venosus (DV) characterized by their timing in the cardiac cycle and evaluate if they can be categorized into distinct patterns.
DV velocity ratios were calculated from peak velocities during ventricular systole (S), endsystolic ventricular relaxation (v), early diastole (D) and atrial systole a; S/v, S/D, v/D, S/a, v/a and D/a ratios). The ratios were converted to their z-scores and >2SD elevation was assigned as abnormal. Combinations of ratio abnormalities were grouped to define distinct waveform patterns and their distribution was related to the clinical presentation.
542 abnormal DV waveforms fell into three principal patterns. Pattern 1: only the a-wave related ratios were abnormal (180, 33.2%). Pattern 2: the v/D ratio was abnormal (143, 26.3%). Pattern 3: combinations of a-wave abnormalities in the presence of a normal v/D ratio was normal (94, 17.3%).
We present a classification for the ductus venosus flow profile that characterizes abnormal flow that is confined to atrial systole, occurs during ventricular relaxation or during holo-diastole. Further research is warranted to determine the significance of these patterns in specific fetal condition.
To investigate time intervals of ductus venosus (DV) flow velocity waveforms (FVW) in correlation to fetal heart rate and gestational age and to construct reference ranges for the second and third trimester. Furthermore, we investigate time intervals of FVW through the tricuspid valve.
Flow velocity waveforms of the DV and through the tricuspid valve were recorded in 135 normal singleton fetuses between 17 and 38 weeks' gestation. Time intervals for systolic (S) and early diastolic (D) peaks were analyzed regarding acceleration time (acc-S for S, acc-D for D) and deceleration time (dec-S for S, dec-D for D), respectively. Similarly, time intervals for both peaks of right ventricular inflow were analyzed regarding acceleration time (acc-E for E-wave, acc-A for A-wave) and deceleration time (dec-E for E-wave, dec-A for A-wave), respectively.
In the DV, acc-D and dec-D increased significantly with gestational age. In tricuspid valve, acc-E and acc-A showed a significant increase with gestational age. All parameters except acc-S showed significant negative correlations with fetal heart rate.
With advancing gestational age, prolongation of the diastolic phase of DV-FVW and of the E-wave of tricuspid flow was observed, suggesting maturation of ventricular diastolic function. Time-related analysis of Doppler signals of DV-FVW may provide detailed insights into fetal cardiac function.