Aortic Waveform Research Articles

Assessment of pressure wave reflection: getting the timing right!

Assessment of timing and magnitude of wave reflection is ideally based on wave separation analysis (WSA). In clinical practice, however, waveform analysis (WFA) is often used to study wave reflection, with different coexisting approaches to assess ‘landmarks’ on the waveform which are indicative for return of the reflected wave. The aim of this work was to compare WSA and WFA. Data were obtained from 2132 subjects (1093 women) aged between 35 and 56 and free from overt cardiovascular disease. Carotid pressure and aortic flow waveforms, and carotid-femoral pulse wave velocity were measured non-invasively. WSA yielded the timing of return of reflected wave (Tf-b), the ratio of forward and backward pressure wave (Pb/Pf), and the effective length of the arterial tree (Leff). WFA resulted in identification of the shoulder (Tsho) or inflection point (Tinf) as landmark points, with subsequently derived augmentation index and Leff (AIxsho and Leff,sho, AIxinf and Leff,inf, respectively). (i) Neither Tinf nor Tsho corresponded with the timing obtained from WSA. (ii) Measurements of Leff were found to decrease with age (conforming with current physiological insights) whilst Leff,inf was found to increase with age in women, and mixed results were obtained for Leff,sho. (iii) Both AIxinf and AIxsho showed a persistent gender difference which was not present in Pb/Pf. Using the pressure at Tf-b to calculate AIx, the systematic gender difference in AIxf-b was greatly reduced. Analysis of pressure wave reflection is optimally based on measurement of pressure and flow, rather than on waveform analysis alone.

Characterization of an Abdominal Aortic Velocity Waveform in Patients with Abdominal Aortic Aneurysm

Haemodynamics studies of abdominal aortic aneurysm require data on the velocity in the normal section of the aorta. Centreline velocity waveforms were measured in abdominal aortic aneurysm patients proximal to the aneurysm using spectral Doppler ultrasound. Characteristic points were automatically found on 21 of the waveforms and their parameters were used to create an archetypal centreline velocity waveform. The maximum velocity was 45 ± 13 cm s −1, the minimum velocity was −15 ± 11 cm s −1 and the maximum diastolic velocity was 2.7 ± 4.7 cm s −1. The velocity wave is suitable for use as an input to in vitro or in silico investigations of abdominal aortic aneurysm haemodynamics. (E-mail: kate.fraser@ed.ac.uk)

Characterization of the Upper Limb Arterial Properties during Reactive Hyperemia

The radial artery (RA) pressure waveform is commonly used to reconstruct the central aortic pressure waveform. Because the RA pressure waveform has been used as input to this process, its features that are dependent on the local arterial properties can influence the final reconstructed aortic waveform. In this study, we determined the effects of altered upper limb pulse wave velocity (PWV) and local wave reflection parameters on RA pressure waveform augmentation (RA-AIx). Twenty healthy volunteers (10 men) between the ages of 18 and 35 years of age were recruited. Simultaneous pressure waveforms were acquired using arterial tonometers from the right carotid and the radial arteries, prior to and following tourniquet induced hyperemia. The phase velocities from the pressure wave transfer function were used to estimate the pulse wave velocity (PWV(infinity)), the local reflection coefficient (Gamma) and an estimate of the terminal impedance of the upper limbs, PWV(0+). The RA-AIx was represented as a linear, three-parameter model that included the input (the AIx of the carotid artery pressure waveform, CA-AIx), the Gamma and PWV(infinity) of the arm. Tourniquet induced hyperemia did not alter Gamma but reduced PWV(infinity), and PWV(0+) and increased RA-AIx. Multiple linear regression analysis indicated that RA-AIx was increased by high levels of CA-AIx and PWV(infinity) and decreased by elevated Gamma. The relative weighing of CA-AIx, Gamma and PWV(infinity) on RA-AIx were 3:2:1, respectively. The AIx of RA is determined to an equal extent by the input and local factors. Interpretation of the AIx of the RA and the reconstructed central aortic waveform should be made in the context of this relationship.

Noninvasive Pulse Waveform Analysis in Clinical Trials: Similarity of Two Methods for Calculating Aortic Systolic Pressure

Concerns persist about the validity of generalized transfer function-derived, aortic blood-pressure measurements during the administration of vasoactive agents in clinical trials. Hence, we compared this transfer-function method with another, which estimates aortic systolic pressure directly from the late systolic shoulder of the radial pressure wave, after administration of placebo, ramipril, or atenolol. We recorded radial pressure pulse waveforms, using a commercially available system, in 30 subjects with >or=1 coronary risk factor in an acute study of ramipril at 10 mg and atenolol at 100 mg. Directly recorded radial and derived aortic pressure pulse waveforms were examined individually and were ensemble-averaged, and the difference between radial and aortic pressure responses was examined. The late systolic shoulder response from radial waveforms was reduced by 15.8 mm Hg (SD, 12.2 mm Hg) more with ramipril than with atenolol. This was similar to a difference of 14.6 mm Hg (SD, 11.2 mm Hg) calculated for the aortic systolic pressure response using the transfer-function technique. Ramipril caused a greater reduction in the aortic systolic pressure response (22.2 mm Hg), whereas with atenolol, there was a modest decrease (7.6 mm Hg). The mean difference between aortic systolic pressures measured from direct radial waveforms and from derived aortic pressure between 3 and 5 h after dosing under all circumstances was 1.6 mm Hg (SD, 8.9 mm Hg). Central pressure derived from radial pressure waveforms using a generalized transfer function gave similar results for central pressure measured directly from radial waveforms. The hemodynamic benefits of angiotensin-converting enzyme inhibitor, angiotensin receptor blocker, and calcium channel blocker over beta-blocker antihypertensive therapy in recent trials were confirmed by this study.

Changes in Aortic Distension Waveforms in Acute Hypoxemia and Acidosis: Fetal Lamb Study

The objective was to investigate the relationship between fetal aortic distension waveforms and fetal hypoxemia and/or acidosis. Aortic distension waveforms were recorded using an echo-tracking system in nine late-gestation catheterized fetal lambs. Under hypoxic conditions induced by inhalation of gas mixture, fetal blood pressure and aortic distension waveforms were recorded. Four parameters, namely peak systolic and end diastolic diameter, amplitude (ΔD) and ratio of ΔD to end diastolic diameter (%ΔD), were obtained, and correlations between these parameters and partial arterial oxygen tension (PaO 2) and pH of fetal blood gas were analyzed. These four parameters were compared between the control, hypoxemic and asphyxic groups. The ΔD and %ΔD were significantly correlated with PaO 2 and pH using linear regression analysis. Both the ΔD and %ΔD decreased significantly, in a stepwise fashion, in the hypoxemic and asphyxiated groups compared with controls using repeated measured analysis of variance. It was concluded that fetal aortic distension waveforms proved to be a useful tool to detect the deterioration in the fetal circulation secondary to intrauterine hypoxemia/asphyxia. (E-mail: satohs@oitakenbyo.jp)

Comparison of the Hemodynamic and Thrombogenic Performance of Two Bileaflet Mechanical Heart Valves Using a CFD/FSI Model

The hemodynamic and the thrombogenic performance of two commercially available bileaflet mechanical heart valves (MHVs)--the ATS Open Pivot Valve (ATS) and the St. Jude Regent Valve (SJM), was compared using a state of the art computational fluid dynamics-fluid structure interaction (CFD-FSI) methodology. A transient simulation of the ATS and SJM valves was conducted in a three-dimensional model geometry of a straight conduit with sudden expansion distal the valves, including the valve housing and detailed hinge geometry. An aortic flow waveform (60 beats/min, cardiac output 4 l/min) was applied at the inlet. The FSI formulation utilized a fully implicit coupling procedure using a separate solver for the fluid problem (FLUENT) and for the structural problem. Valve leaflet excursion and pressure differences were calculated, as well as shear stress on the leaflets and accumulated shear stress on particles released during both forward and backward flow phases through the open and closed valve, respectively. In contrast to the SJM, the ATS valve opened to less than maximal opening angle. Nevertheless, maximal and mean pressure gradients and velocity patterns through the valve orifices were comparable. Platelet stress accumulation during forward flow indicated that no platelets experienced a stress accumulation higher than 35 dyne x s/cm2, the threshold for platelet activation (Hellums criterion). However, during the regurgitation flow phase, 0.81% of the platelets in the SJM valve experienced a stress accumulation higher than 35 dyne x s/cm2, compared with 0.63% for the ATS valve. The numerical results indicate that the designs of the ATS and SJM valves, which differ mostly in their hinge mechanism, lead to different potential for platelet activation, especially during the regurgitation phase. This numerical methodology can be used to assess the effects of design parameters on the flow induced thrombogenic potential of blood recirculating devices.

Abnormal fetal aortic velocity waveform and postnatal growth

Abnormal fetal aortic velocity waveform and postnatal growth

Letter by Cameron et al Regarding Article, “Differential Impact of Blood Pressure-Lowering Drugs on Central Aortic Pressure and Clinical Outcomes: Principal Results of the Conduit Artery Function Evaluation (CAFE) Study”

To the Editor: We read with interest the report of the Conduit Artery Function Evaluation (CAFE) study1 showing a difference in SphygmoCor-derived central systolic blood pressure (SBP) between the 2 arms of an Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) substudy (despite similar brachial blood pressure changes). We would make 3 points. First, the authors seem to have misinterpreted our work (authors’ Reference 53)2 as showing a “precision” of 1 mm Hg between calculated central aortic and directly measured SBP in the context of noninvasive studies. This figure relates to …

Continuous cardiac output monitoring by blood pressure analysis

to the editor: Monitoring of continuous cardiac output (CO) allows for the detection of rapid changes in systemic flow that would otherwise be unnoticed by the recording of arterial pressure and heart rate. Continuous tracking of changes in stroke volume (SV) can be obtained by arterial pulse wave

OP07.17: Identification of fetuses at risk of perinatal mortality by the combination of ductus venosus, myocardial performance index and aortic isthmus Doppler waveforms

Objective: To study the aortic isthmus (AoI) circulation in preterm growth-restricted fetuses (IUGR). Methods: Fifty one IUGR fetuses with either an umbilical artery (UA) pulsatility index (PI)>95th centile or a cerebroplacental ratio 95th centile was shown in 21/51 cases (41%). No adverse perinatal outcome was significantly associated with neither a high PI or low absolute velocities. Comparing group 1 (anterograde) and group 2 (retrograde) significant differences were found in birth weight (p < 0.01), gestational age at delivery (p < 0.001), UA pH values (p < 0.001) and need of mechanical ventilation (p < 0.01). Perinatal mortality was higher in group 2 than group 1 (5.7% vs 60%; p < 0.001). A significant correlation (p < 0.001) was found between retrograde flow in the AoI and adverse perinatal outcome. Conclusions: The decrease in AoI absolute velocities is likely to reflect a decrease in AoI blood flow. Retrograde blood flow in the AoI is clearly related to adverse perinatal outcome.

Enhanced External Counterpulsation Treatment Improves Arterial Wall Properties and Wave Reflection Characteristics in Patients With Refractory Angina

To determine if arterial properties and wave reflection characteristics are favorably altered after enhanced external counterpulsation (EECP) treatment in patients with refractory angina. Early return of reflected waves from the lower body, resulting from increased arterial stiffness, augments central aortic pressure and increases left ventricular (LV) afterload and myocardial oxygen demand. EECP acutely enhances coronary perfusion (supply) and reduces LV afterload (demand). However, the mechanisms responsible for the sustained beneficial effects of EECP treatment are unclear. Radial artery pressure waveforms were recorded by applanation tonometry and central aortic pressure waveforms generated using a mathematical transfer function in 20 patients with stable refractory angina. Data were collected before and after 34 1-h EECP sessions. Augmentation index (AI(a)) and timing of the reflected pressure wave were calculated from the aortic waveform. EECP treatment caused a decline in AI(a) and an increase in reflected wave travel time. These modifications in wave reflection characteristics caused a decrease in aortic systolic pressure and wasted LV pressure energy. The average number of angina episodes and Canadian Cardiovascular Society (CCS) class, both decreased in concordance with the physiologic changes due to EECP treatment. EECP treatment reduces arterial stiffness and improves wave reflection characteristics in patients with refractory angina. These changes decrease LV afterload and myocardial oxygen demand and reduce the number of angina episodes, therefore enabling patients to participate in continuous exercise programs which in turn may provide long-term benefits and sustained improved quality of life.

At the Beginning of Stiffening

Brachial cuff blood pressure (BP) continues to guide almost every decision related to the clinical management of the hypertensive patient. However, the BP within the central aorta (ie, aortic pressure) is receiving growing attention for 2 main reasons. First, brachial BP does not necessarily predict aortic pressure, and subjects with equal values of brachial cuff pressure may differ markedly in their aortic pressure.1 Second, aortic pressure may be superior to brachial BP for the prediction of several vascular complications, including the degree of carotid atherosclerosis,2 the extent of coronary artery disease,3 the likelihood of reocclusion after angioplasty,4 and, more important, the risk of major cardiovascular events.1,5 Aortic BP may be estimated noninvasively from analysis of peripheral radial artery waveforms with applanation tonometry. Although the reliability of derived aortic BP is crucially dependent on the validity of the transfer function used to generate the central aortic waveforms, the correspondence between estimated central aortic and intra-arterial systolic BP and pulse pressure (PP) seems to be quite close.6 In addition to central PP, pulse …

Triangulating the Peaks of Arterial Pressure

Increased arterial stiffness and excessive pressure pulsatility have emerged as important risk factors for a number of common disorders of aging, including cardiovascular disease, stroke, cognitive impairment, and renal disease. The triple-threat combination of robust associations between arterial stiffness and the foregoing disorders, a marked increase in arterial stiffness with advancing age and the graying of our society, has led to intensive efforts to identify mechanisms that contribute to arterial stiffening and widening pulse pressure to define interventions to prevent or reverse stiffness and potentially reduce the substantial burden of related disease. Wave reflections complicate the task of evaluating arterial hemodynamics and play an unclear role in the foregoing diseases. When the heart ejects, ventricular outflow interacts with characteristic impedance of the proximal aorta to produce the forward pressure wave, which travels down the normally compliant aorta at a finite pulse wave velocity (PWV). When the forward wave encounters impedance mismatch, such as a branch point or a change in diameter or wall properties, a partial reflection occurs. Innumerable reflections arising from locations distributed throughout the arterial tree summate into a remarkably discrete reflected pressure wave with amplitude ≈40% of the incident wave. The summated reflected wave returns to the central aorta in midsystole, creating an inflection point and secondary late systolic pressure rise that often augments central aortic systolic and pulse pressure.1 Variable timing of this retrograde-traveling reflected wave creates regional inequalities in systolic and pulse pressure and, therefore, complicates interpretation of single point pressure measurements, such as standard brachial blood pressure, which may differ from central aortic pressure. Augmentation index (AI), which expresses late systolic pressure augmentation as a percentage of pulse pressure, is frequently used to assess wave reflection (Figure). AI, which depends on both timing and amplitude of the reflected wave, has also been widely …

1201: Fetal aortic blood flow velocity waveform: Effect of gestational age and its sampling points

Fetal arterial blood flow velocity waveforms of umbilical artery or middle cerebral artery have been widely used for estimation. Fetal descending aortic flow was used for fetal estimation and the end-diastolic reversed flow or absent end-diastolic flow of descending aorta was reported as those of umbilical arterial flow. But the umbilical arterial flow waveforms are more easily acquired than those of descending aorta, and recently the latter has not been used for fetal estimation. Otherwise, fetal descending aorta is able to be visualized linearly by 2D ultrasonography, and the blood flow velocity itself is able to be measured accurately when adequate insonation angle is acquired. Evaluation of fetal blood flow velocity might be useful tool for the fetal cardiac function. We cross-sectionally examined fetal descending aortic blood flow velocity waveforms from 551 normal singleton fetuses between 18 to 41 weeks of gestation in order to establish the reference values the Doppler indices (resistance index and maximum systolic velocity) and to clarify the characteristics of fetal aortic flow velocity waveform. Doppler flow velocity waveforms were acquired from three different sampling points: thoracic (behind fetal heart), upper abdominal (just below diaphragm) and lower abdominal (just below the origination of renal arteries) portions in each fetus. The resistance indices for the fetal descending aorta decreased from thoracic to lower abdominal portion, but no remarkable change was detected during fetal development (0.84 ± 0.05, 0.79 ± 0.04, 0.76 ± 0.05, thoracic, upper abdominal and lower abdominal, respectively, at 18 to 19 weeks of gestation, and 0.85 ± 0.03, 0.81 ± 0.02, 0.73 ± 0.05 at 40 to 41 weeks). Otherwise, maximum systolic velocity decreased from central to peripheral portion and increased during fetal development (69 ± 11, 58 ± 10, 49 ± 8 cm/s, thoracic, upper abdominal and lower abdominal, respectively, at 18 to 19 weeks of gestation, 134 ± 13, 112 ± 18, 92 ± 12 cm/s at 40 to 41 weeks). Moreover, fetal descending aortic flow velocity waveforms sometimes revealed systolic multiple peaks pattern and/or early-diastolic reversed flow patterns. These characteristic flows were more frequently observed in late third trimesters. Interestingly, they were more frequently observed at thoracic portion than at lower abdominal portion. There were no fetuses that revealed these characteristic flows at 18 to 19 weeks of gestation. But, multiple systolic peaks patterns were detected at thoracic, upper abdominal and lower abdominal portions in 64.3%, 42.8% and 35.7% of fetuses at 40 to 41 weeks of gestation. We also detected 9.1%, 3.6% and 1.8% of fetuses at 37 to 38 weeks of gestation at thoracic, upper abdominal and lower abdominal portions, respectively. In conclusion, we resulted that the Doppler flow velocity waveforms are affected by the sampling points on the fetal descending aorta. The resistance index and the maximum systolic velocity for the descending aorta gradually decrease from the thoracic to the lower abdominal portion. These changes are obviously detected throughout the course of pregnancy after 18 weeks of gestation.

Inflection point of ascending aortic waveform is a predictive factor for major adverse cardiac events after successful coronary stent placement in acute myocardial infarction

Objective — The reflection waveform in the ascending aortic pressure has been reported to reflect systemic arterial stiffness, and increase the risk of coronary heart disease.The purpose of this study is to evaluate prospectively whether the reflection waveform in the ascending aortic pressure is associated with the risk of major adverse cardiac events (MACE) after successful coronary stenting in acute myocardial infarction (AMI).Methods and results — One hundred and twenty-five patients with AMI and undergoing successful coronary stenting were enrolled in this study.We measured the inflection time to determine the reflection waveform in the ascending aortic pressure at angioplasty. Inflection time was defined as the time interval from initiation of a systolic pressure waveform to the inflection point. During a period of 2945 person-months, we confirmed 42 cases of MACE. Shorter inflection time increased incident MACE. Kaplan-Meier analysis demonstrated a significantly reduced event-free rate in patients with inflection time ≤ 86 ms (MACE; p < 0.01, cardiovascular death; p < 0.001 by log-rank test).The multiple-adjusted hazard ratio for a 1 standard deviation (SD) magnitude decrease in inflection time was 1.46 (95% confidence interval, 1.03 to 2.05) for MACE, and 5.76 (95% confidence interval, 1.78 to 18.67) for cardiovascular death.Conclusions — Shorter inflection time increased the risk of MACE after successful coronary stenting in patients with AMI.

Fetal aortic distension waveforms for evaluating cardiac function and changes in blood pressure: Fetal lamb validation

To investigate which part of the fetal aortic distension waveform is mainly influenced by changes in fetal cardiac contractility and aortic blood pressure. In acute preparation, aortic distension waveforms were recorded using an echo-tracking system, and aortic and left ventricular pressure waveforms were obtained from six late-gestation catheterized fetal lambs. Dobutamine and angiotensin II were separately infused and the correlations between the maximum value in the first derivative of left ventricle pressure waveforms (Max dP/dt) and fetal blood pressure, and the parameters obtained from aortic distension waveforms were analyzed using linear regression analysis. With a change in cardiac contractility, the maximum value of first derivative of the systolic rising slope in the aortic distension waveform had a positive correlation with Max dP/dt (r = 0.93, P < 0.0001). With changes in fetal blood pressure, both the amplitude and the ratio of increase from the end diastolic diameter obtained from the aortic distension waveform had a significant positive correlation with aortic blood pressure amplitude (r = 0.60, P < 0.01; r = 0.61, P < 0.01, respectively). The maximum first derivative of the systolic rising slope in the aortic distension waveform and the amplitude in the aortic distension waveform enable us to non-invasively substitute for fetal cardiac contractility and aortic blood pressure amplitude, respectively.

Surrogate Measures of Arterial Stiffness

Recent epidemiological studies have shown that arterial stiffness, measured through carotid-femoral pulse wave velocity (PWV), has an independent predictive value for cardiovascular (CV) events in several populations, including patients with uncomplicated essential hypertension1,2 and type 2 diabetes.3 Arterial stiffness is thus an intermediate end point for CV events, predicting CV events independently of and beyond peripheral pulse pressure (PP). Peripheral PP, central PP, and augmentation index, which provide additional information on wave reflection, are considered “surrogates” of arterial stiffness, because their pathophysiological meaning is clearly different.4–6 Central PP and augmentation index are dependent on the speed of wave travel, the amplitude of reflected wave, the reflectance point, and the duration and pattern of ventricular ejection, especially with respect to change in heart rate and ventricular contractility. Aortic PWV, which is the speed of wave travel, represents intrinsically arterial stiffness, according to the Bramwell-Hill formula.4–6 Two articles7,8 in the present issue of Hypertension raise the issue of the predictive value of “surrogates of arterial stiffness” for CV events. Li et al7 studied the dynamic relationship between diastolic blood pressure (DBP0 and systolic blood pressure (SBP) in ambulatory blood pressure monitoring (ABPM) data throughout the day and calculated a novel index as 1− the regression slope of DBP on SBP. This index was named ambulatory arterial stiffness index (AASI) on the basis that “average distending BP …

Non‐invasive pulsatile arterial pressure and stroke volume changes from the human finger

In this paper we review recent developments in the methodology of non-invasive finger arterial pressure measurement and the information about arterial flow that can be obtained from it. Continuous measurement of finger pressure based on the volume-clamp method was introduced in the early 1980s both for research purposes and for clinical medicine. Finger pressure tracks intra-arterial pressure but the pressure waves may differ systematically both in shape and magnitude. Such bias can, at least partly, be circumvented by reconstruction of brachial pressure from finger pressure by using a general inverse anti-resonance model correcting for the difference in pressure waveforms and an individual forearm cuff calibration. The Modelflow method as implemented in the Finometer computes an aortic flow waveform from peripheral arterial pressure by simulating a non-linear three-element model of the aortic input impedance. The methodology tracks fast changes in stroke volume (SV) during various experimental protocols including postural stress and exercise. If absolute values are required, calibration against a gold standard is needed. Otherwise, Modelflow-measured SV is expressed as change from control with the same precision in tracking. Beat-to-beat information on arterial flow offers important and clinically relevant information on the circulation beyond what can be detected by arterial pressure.

The selective alpha-adrenergic receptor agonist dexmedetomidine (DEX) does not affect aortic pressure augmentation

Background Despite a similar reduction in peripheral blood pressure (BP), antihypertensive drugs have variable effects on central blood pressure and its augmentation by the reflected pulse wave, a measure of arterial stiffness. Infusion of norepinephrine (NE) increases arterial stiffness. Centrally acting alpha2-AR agonists decrease NE concentrations and blood pressure, but their effects on aortic pressure augmentation are not known. Methods In a single-blind, placebo-controlled study, 36 healthy subjects received sequential infusions of placebo and DEX (0.1, 0.15 and 0.15 mcg/kg). Brachial artery blood pressure, heart rate, and NE plasma concentrations were measured at baseline and after every infusion. Radial artery waveforms were recorded by applanation tonometry (Sphygmocor) and the central aortic waveform and augmentation index - the proportional increase in systolic pressure due to the reflected wave - calculated. Results DEX reduced brachial and central systolic (−15.0±6.2 (SD) and −12.6±5.8 mmHg) and diastolic BP (−9.9±6.5 and −10.1±6.6 mmHg), respectively (p<0.001). NE levels decreased (−103±68 pg/mL, p<0.001) but augmentation index did not change (placebo 3.4±10.3% vs DEX 3.0±10.1%, P=0.8). Conclusion DEX reduced NE concentrations and central and peripheral blood pressure but did not alter aortic pressure augmentation. Pharmacological reduction of endogenous baseline NE concentrations did not alter arterial stiffness and pulse wave reflection. Clinical Pharmacology & Therapeutics (2005) 77, P11–P11; doi: 10.1016/j.clpt.2004.11.046

Apport pronostique du Doppler de l’isthme aortique fœtal dans la prise en charge du retard de croissance intra-utérin: Étude prospective longitudinale

Our purpose was to determine whether the use of aortic isthmus Doppler waveform analysis in growth restricted fetuses delivered at 28 to 38 weeks predicts perinatal outcomes.Prospective longitudinal study including singleton non-malformed euploid fetuses with accurate dating and diagnosed as growth restricted (abdominal circumference<10th percentile) and who were followed up at our institution and delivered<10 days after the last Doppler. Timing of delivery was collegial. Perinatal mortality and morbidity outcomes were compared in cases with anterograde blood flow versus retrograde net blood flow in aortic isthmus. Relative risk (RR) were calculated with 95% CI and P<0,05 was considered significant.Thirty-two cases were considered for analysis: growth-restricted foetuses with anterograde blood flow (n=26) versus retrograde net blood (n=6). Maternal demographic characteristics in the two groups were similar and exceptions made of femur length average values for fetal biometrics were not significantly different. Doppler velocimetry results at the uterine, umbilical and cerebral arteries were similar in the two groups. Gestational age at delivery and birth weight were similar in both groups (respectively (239.65 20.1 vs. 247.3 16.4 (days) (p=0.349) and 1748.8 gr 468.7 vs. 1933.3 gr 468.7 (p=0.408)). There was a statistically significant increase in perinatal mortality in retrograde net blood flow group: 8.66 [IC 95% 2.03 - 36.84]. An interesting finding was that neonates with aortic isthmus retrograde net blood flow were more frequently born by cesarean delivery because of a suspected fetal compromise RR=3.22 CI 95% [1.29-8].In our study Doppler identification of aortic isthmus retrograde net blood flow in growth-restricted fetuses was associated with an increase of perinatal death.