Computer Modeling of Carotid Endarterectomy With the Different Shape Patches and Prediction of the Atherosclerotic

Objective: The article describes a method for constructing geometric models of the carotid bifurcation and computer simulation of endarterectomy surgery with the patches of various configurations. The purpose of this work is to identify the areas of the greatest risk of restenosis in the constructed models and to conduct a comparative analysis of risk factors when using the patches of different widths and shapes. Methods: The method is demonstrated on a reconstructed model of a healthy vessel. Its building is based on a preoperative computed tomography study of a particular patient's affected vessel. The flow in the vessel is simulated by computational fluid dynamics using data from the patient's ultrasound Doppler velocimetry. Risk factors are assessed through the hemodynamic indices on the vessel wall associated with Wall Shear Stress. Results: The distribution of risk zones in the healthy vessel, presumably leading to its observed lesion (plaque), is analyzed. Comparative evaluation of 10 various patches implantation results is carried out and the optimal variant is determined. The proposed method can be used to predict the hemodynamic results of surgery using patches of various sizes and shapes.

Umbilical artery pulsatility index and half-peak systolic velocity in second- and third-trimester fetuses with trisomy 18 and 13

Objectives To analyze umbilical artery (UA) Doppler velocimetry and its possible role in placenta-mediated fetal growth restriction (FGR) in second- and third-trimester fetuses with trisomy 18 and 13. Methods UA pulsatility index (PI) and half-peak systolic velocity deceleration time (hPSV-DT) were measured in fetuses with trisomy 18 and 13. Correlation with gestational age, birthweight, and perinatal outcome was analyzed. Results A total of 80 measurements were taken from 33 fetuses with trisomy 18 and 19 with trisomy 13. Overall, there was a high prevalence of abnormal UA Doppler velocimetry. In fetuses with trisomy 18, 54% (27/50) of the UA PI values and 58% (29/50) of the UA hPSV-DT values were abnormal. In fetuses with trisomy 13, 80% (24/30) of the UA PI values and 87% (26/30) of the UA hPSV-DT values were abnormal. The prevalence of abnormal UA Doppler velocimetry increased with gestational age in both types of aneuploidy. However, this trend was only significant for trisomy 13 (p<0.05). All fetuses with trisomy 18 and 86% of fetuses with trisomy 13 were classified at birth as FGR. There were no perinatal survivors in this series. Conclusions A high prevalence of abnormal UA Doppler velocimetry was found in second- and third-trimester fetuses with trisomy 18 and 13, which further increased with gestational age. These results may well correlate with alterations described previously in the placenta, suggesting placental insufficiency has an important role in the development of FGR in these autosomal aneuploid fetuses.

A sex specific approach of ophthalmic and middle cerebral arteries Doppler in smokers

Vascular dysfunctions can progress and lead to stroke and cardiovascular disease, especially in smokers. The presence of particular vascular changes according to sex has been described and they can be identified by the Doppler method. This study evaluated Doppler velocimetry parameters of the Ophthalmic Artery (OA) and the Middle Cerebral Artery (MCA) according to sex in smokers regarding a non-smoker group. This cross-sectional observational study included 178 subjects: 93 women and 85 men. Doppler parameters were assessed in OA and MCA. Student’s t-test was used, with p < 0.05. There were no significant differences in OA and MCA Doppler velocimetry data between male non-smokers and smokers. However, female smokers presented several differences compared with non-smokers: lower pulsatility index (PI) and higher peak ratio in OA, and higher PI and resistance index and lower end diastolic velocity in MCA. There were different brain vascular waveforms in the group of female smokers compared with non-smokers. Cigarette smoking also led to opposite arterial patterns in OA and MCA in the female group, with signs of falling impedance in OA and increased impedance in MCA. An individualized approach regarding arterial changes according to sex is desirable.

The Effects of the Width of an Isolated Valley on Near-Surface Turbulence

With the aim of ascertaining the effects of the widths (A) of valleys on near-surface turbulence, flows over an isolated symmetric three-dimensional valley of constant depth (H) and slopes are characterized in a large-boundary-layer wind tunnel. Starting at A = 4H, valley widths were systematically varied to A = 12H with constant increments of 2H. High-resolution laser-Doppler velocimetry measurements were made at several equivalent locations above each of the resulting valley geometries and compared with data from undisturbed flows over flat terrain. Flow separation caused by the first ridges generated inner-valley recirculation bubbles with lengths dependent on the valley widths. Secondary recirculation zones were also observed downstream from the crests of the second ridges. Results show that the width modifications exert the strongest effects on turbulence within the valleys and the vicinities of the second ridges. Above these locations, maximal magnitudes of turbulence are generally found for the larger width geometries. Furthermore, lateral turbulence overpowers the longitudinal counterparts nearest to the surface, with maximal gains occurring for the smaller widths. Our data indicate that valley widths are impactful on near-surface flows and should be considered together with other more established geometric parameters of influence.

Doppler Velocimetry evaluation in high-risk pregnancy for prediction of Preeclampsia

Background: The uterine and umbilical artery Doppler scan is a valuable tool for evaluation of utero-placental blood flow in pregnancy. They help in detecting uteroplacental insufficiency thus predicting preeclampsia and other effects of faulty placentation which increase the risk of adverse effects on both mother and fetus. Aims and Objective: This study aimed to evaluate and compare the uterine artery and umbilical artery Doppler indices in second and third trimester for prediction of preeclampsia in high-risk pregnancies. Materials and Methods: In this prospective observational study done over a years’ time, 50 high-risk pregnant mothers were recruited and the Doppler scans were done at 21-25 weeks and 31-35 weeks. The necessary clinical observations were recorded throughout the antenatal period and the data analysis was done. Results: Majority (56%) were in 20-29 years range with mean age of 24±6.1 years. Out of the 50 women, 21 had abnormal uterine artery Doppler and 12 had umbilical artery abnormality along with uterine derangement. Preeclampsia developed in 3 of them. The hypertensive disorders of pregnancy were diagnosed in 13 women, preeclampsia in 3, eclampsia in 1and other HDPs in 9. The persistence of notch in uterine artery was observed in 7 women, of these 2 developed PIH. Only one patient had uterine artery PI>1.45 at 24 weeks who subsequently developed preeclampsia. Among 4 patients of preeclampsia and eclampsia, 3 had 2nd trimester uterine and 3rd trimester umbilical Doppler abnormalities and only 1 had normal doppler indices. In 2nd trimester the sensitivity, specificity and PPV are higher for uterine artery PI as compared to umbilical artery PI. Hence, uterine artery doppler seems to be a better screening tool for early prediction of PIH. The third trimester umbilical artery PI with higher specificity (96%) and PPV (50%) can diagnose preeclampsia better. One patient had absent diastolic flow and she developed preeclampsia and IUGR. The combined uterine and umbilical artery doppler is a better screening modality as it has a higher sensitivity (75%) and NPV (99.26%). Conclusion: The uterine and umbilical artery Doppler velocimetry are potential tools for uteroplacental surveillance of high-risk pregnancies which can identify patients at risk and help in taking timely action to prevent complications.