scholarly journals Modeling of the Hemodynamics of Vascular Prostheses "Kemangiprotez" in Silico

2017 ◽  
Vol 12 (2) ◽  
pp. 559-569 ◽  
Author(s):  
К.Ю. Клышников ◽  
K.U. Klyshnikov
Keyword(s):  
Clinical Medicine ◽  
Vascular System ◽  
Thrombus Formation ◽  
Peak Systolic Velocity ◽  
Fluid Flows ◽  
Vascular Prostheses ◽  
Diastolic Velocity ◽  
Proximal Site ◽  
Critical Zones ◽  
Vascular Replacement

The paper describes aspects of the application of numerical simulation of fluid flows in clinical medicine with interventions on the human vascular system. The modeling method used in the study is verified using the data of the doppler sonography of the patient underwent vascular replacement. It was shown that the deviation between the numerical experiment and the clinical data - pressure curves at the inlet and outlet of the studied vessel, is 20%. The obtained quantitative characteristics of the flow: peak systolic velocity, final diastolic velocity, minimum diastolic velocity, resistivity index, pulsatility index, systole/diastole index are comparable between verification and experimental data. Thus, for the proximal site of the clinical vessel the corresponding indices were 96.5 cm/s; 4.5 cm/s; 36.2 cm/s; 1.05; 11.5; 21.3. For simulation, 107.9 cm/s; 4.44 cm/s; 43.9 cm/s; 1.05; 12.0; 24.3. In addition, the work describes the application of tested method in two clinical vascular prostheses "KemAngioprotez" for the assessment of zones of increased shear stress and, thus, the risk of thrombus formation. It is shown that the distribution of critical zones corresponds to zones of anastomosis between prosthesis segments, which may be a potential location for optimization of the device.

Naturally Produced Extracellular Matrix Is an Excellent Substrate for Canine Endothelial Cell Proliferation and Resistance to Shear Stress on PTFE Vascular Grafts

1997 ◽  
Vol 78 (05) ◽  
pp. 1392-1398 ◽  
Author(s):  
A Schneider ◽  
M Chandra ◽  
G Lazarovici ◽  
I Vlodavsky ◽  
G Merin ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Shear Stress ◽  
Endothelial Cell ◽  
Cell Attachment ◽  
Thrombus Formation ◽  
Endothelial Cell Proliferation ◽  
Ptfe Graft ◽  
Vascular Prostheses ◽  
Endothelial Cell Attachment

SummaryPurpose: Successful development of a vascular prosthesis lined with endothelial cells (EC) may depend on the ability of the attached cells to resist shear forces after implantation. The present study was designed to investigate EC detachment from extracellular matrix (ECM) precoated vascular prostheses, caused by shear stress in vitro and to test the performance of these grafts in vivo. Methods: Bovine aortic endothelial cells were seeded inside untreated polytetrafluoro-ethylene (PTFE) vascular graft (10 X 0.6 cm), PTFE graft precoated with fibronectin (FN), or PTFE precoated with FN and a naturally produced ECM (106 cells/graft). Sixteen hours after seeding the medium was replaced and unattached cells counted. The strength of endothelial cell attachment was evaluated by subjecting the grafts to a physiologic shear stress of 15 dynes/cm2 for 1 h. The detached cells were collected and quantitated. PTFE or EC preseeded ECM coated grafts were implanted in the common carotid arteries of dogs. Results: While little or no differences were found in the extent of endothelial cell attachment to the various grafts (79%, 87% and 94% of the cells attached to PTFE, FN precoated PTFE, or FN+ECM precoated PTFE, respectively), the number of cells retained after a shear stress was significanly increased on ECM coated PTFE (20%, 54% and 85% on PTFE, FN coated PTFE, and FN+ECM coated PTFE, respectively, p <0.01). Implantation experiments in dogs revealed a significant increase in EC coverage and a reduced incidence of thrombus formation on ECM coated grafts that were seeded with autologous saphenous vein endothelial cells prior to implantation. Conclusion: ECM coating significantly increased the strength of endothelial cell attachment to vascular prostheses subjected to shear stress. The presence of adhesive macromolecules and potent endothelial cell growth promoting factors may render the ECM a promising substrate for vascular prostheses.

Doppler evaluation of the posterior cerebral artery in fetuses with transposition of great arteries

2020 ◽  
Vol 48 (5) ◽  
pp. 504-508
Author(s):  
Ya Tan ◽  
Shi Zeng ◽  
YuShan Liu ◽  
HuaYu Tang ◽  
BaiHua Zhao
Keyword(s):  
Cerebral Artery ◽  
Pulsatility Index ◽  
Posterior Cerebral Artery ◽  
Cerebral Arteries ◽  
Peak Systolic Velocity ◽  
Transposition Of Great Arteries ◽  
Velocity Time Integral ◽  
Time Integral ◽  
Diastolic Velocity ◽  
Doppler Evaluation

AbstractObjectiveTo observe Doppler ultrasound changes in the two segments of the posterior cerebral artery (PCA) in fetuses with transposition of the great arteries (TGA).MethodsThe peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and velocity-time integral (VTI) of the two segments of PCA (the first segment: PCAS1, the second segment: PCAS2) and of the middle cerebral artery (MCA) were compared in TGA fetuses and normal fetuses. The abnormality rate between the PCAS1-PI and MCA-PI was compared in TGA fetuses.ResultsThe PCAS1-PI and MCA-PI were smaller in the TGA fetuses than in the controls (all P < 0.05), but the PCAS2-PI was unchanged (P > 0.05). The MCA-VTI, PCAS1-VTI, and PCAS2-VTI were larger in the TGA fetuses (all P < 0.05). In the TGA fetuses, the abnormality rate of the PCAS1-PI was significantly higher than that of the MCA-PI (P < 0.05).ConclusionIn fetuses with TGA, there were hemodynamic differences between the two segments of the posterior cerebral arteries. Moreover, PCAS1 exhibited signs of vasodilatation more obviously than did the MCA in fetuses with TGA.

scholarly journals Post-exercise pulsatility index indicates treatment effects in peripheral arterial occlusive disease (PAOD)

2021 ◽  
Author(s):  
Andrej Udelnow ◽  
Maria Hawemann ◽  
Ivo Buschmann ◽  
Frank Meyer ◽  
Zuhir Halloul
Keyword(s):  
Repeated Measures ◽  
Pulsatility Index ◽  
Treatment Effects ◽  
Resistance Index ◽  
Peak Systolic Velocity ◽  
Arterial Tree ◽  
Post Exercise ◽  
Diastolic Velocity ◽  
Before And After ◽  
Healthy Persons

Summary Background Hypothesis: Post-exercise measurements better discriminate PAOD-patients from healthy persons and they more sensitively detect hemodynamic improvements after treatment procedures than resting measurements. Methods A total of 19 healthy volunteers and 23 consecutive PAOD-patients underwent measurements of peak systolic velocity (PSV), end-diastolic velocity (EDV), minimal diastolic velocity (MDV), time-averaged maximum velocities (TAMAX), resistance index (RI) and pulsatility index (PI) before and after a standard exercise test (at 1, 2, 3, 4 and 5 min) before and after treatment (incl. epidemiological data, PAOD risk factors and comorbidities). Results In resting values, healthy persons and PAOD-patients did not differ significantly in any of the hemodynamic parameters. PSV increased after treatment in PAOD-patients by 5 cm/s (paired t‑test, p: 0.025); however, when the amplitude of autoregulatory changes related to the resting values were calculated, PAOD-patients showed clearly less hemodynamic changes after exercise than healthy persons (p: 0.04; 0.002; <0.001 for PSV, TAMAX and PI, resp.). The time course after exercise was compared by repeated measures of ANOVA. Healthy persons differed significantly in PI, RI and PSV from PAOD patients before and after treatment (p<0.001 each). The PAOD-patients revealed a significantly improved PI after treatment (p: 0.042). The only factor contributing significantly to PI independently from grouping was direct arterial vascularization as compared to discontinuous effects by an obstructed arterial tree. Conclusion Healthy persons cannot be well differentiated from PAOD-patients solely by hemodynamics at rest but by characteristic changes after standard exercise. Treatment effects are reflected by higher PI-values after exercise.

scholarly journals Feasibility of Ultrafast Doppler technique for cranial ultrasound in neonates

2019 ◽  
Vol 21 (3) ◽  
pp. 288
Author(s):  
Hyun Gi Kim ◽  
Jang Hoon Lee
Keyword(s):  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Posterior Cerebral Artery ◽  
Peak Systolic Velocity ◽  
Resistive Index ◽  
Quantitative Information ◽  
Cranial Ultrasound ◽  
Doppler Us ◽  
Diastolic Velocity ◽  
Cranial Arteries

Aims: The aim of this study was to compare the performances of Ultrafast Doppler ultrasound (US) with classic Doppler US, for cranial ultrasound in neonates.Materials and methods: We measured the peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) of the anterior cerebral artery (ACA), middle cerebral artery (MCA) and posterior cerebral artery (PCA) in neonates using both conventional and Ultrafast Doppler US and acquisition times were compared. Distal ACA branches were assessed with Ultrafast Doppler US.Results: A total of 138 neonates were included. The PSV and EDV of the cranial arteries were comparable between the two Doppler methods (PSV, 64.6-85.5 cm/s vs. 63.4-84.1 cm/s, p=0.100-0.510; EDV, 19.1-26.5 cm/s vs. 17.8-24.2 cm/s, p=0.100-0.981). The RIs of the ACA and PCA were not significantly different (0.69-0.73 vs 0.68-0.74, p=0.174-0.810). Ultrafast Doppler US required shorter acquisition times than conventional Doppler US (6.7 s vs. 11.0 s, p=0.003). The PSV and EDV of the distal ACA were higher than the proximal ACA (20.1-63.3 cm/s vs. 9.4-36.7, p<0.001) although the RI was similar (0.69 vs. 0.68, p=0.251).Conclusions: Ultrafast Doppler US provides comparable values to conventional Doppler US with shorter acquisition times. This novel imaging technique provides quantitative information and is suitable for distal cranial artery evaluation.

Estimation of haemodynamic changes in varicocele testis and results after microsurgical sub-inguinal varicocelectomy

2021 ◽  
pp. 039156032110690
Author(s):  
Satyadeo Sharma ◽  
Rajendra K Shimpi
Keyword(s):  
Semen Analysis ◽  
Peak Systolic Velocity ◽  
Resistive Index ◽  
Semen Parameters ◽  
Medical Institute ◽  
Sperm Density ◽  
Doppler Study ◽  
Diastolic Velocity ◽  
Before And After ◽  
Haemodynamic Changes

Introduction: Varicocele is among the most frequently encountered, surgically correctable causes of male infertility. Since varicocele is a primary abnormality of testicular vessels, a thorough understanding of haemodynamic changes in the microcirculation of varicocele testis is needed. Objectives: To estimate changes in the microcirculation of varicocele testis and correlate them with symptomatic and semen parameters changes before and after varicocelectomy. Material and methods: This prospective, observational study includes 47 patients of age group 18–40 years who underwent microsurgical varicocelectomy during June 2016 to April 2018 at a tertiary medical institute. Testicular haemodynamic was evaluated using a colour spectral doppler study (PSV-Peak systolic velocity/ESV-End diastolic velocity/RI-Resistive index/PI-Pulsatility index). Semen analysis parameters and testicular blood flow were compared with pre-operative values. Results: RI in the capsular artery of varicocele affected testis, which was 0.61 ± 0.11 (mean ± SD), significantly reduced to 0.56 ± 0.09 (mean ± SD) in post-operative follow-up, indicating improved perfusion. Pre-operative sperm density was noted to be 15.94 ± 7.88 (mean ± SD), which improved to 28.41 ± 10.99, Progressive sperm motility from 33.81 ± 10.88 to 38.32 ± 9.21 and morphology from 36.13 ± 10.68 to 41.43 ± 9.29 on 6-month follow-ups ( p < 0.05). Conclusion: Varicocele testis is associated with altered testicular haemodynamic, which insults spermatogenesis. Microsurgical varicocelectomy with testicular artery and lymphatic preservation leads to correction of this altered haemodynamic state and improves the testicular microcirculation.

scholarly journals Systemically Administered, Target-Specific, Multi-Functional Therapeutic Recombinant Proteins in Regenerative Medicine

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 226 ◽  
Author(s):  
Tero A.H. Järvinen ◽  
Toini Pemmari
Keyword(s):  
Regenerative Medicine ◽  
Blood Vessels ◽  
Recombinant Proteins ◽  
Clinical Medicine ◽  
Vascular System ◽  
Therapeutic Potential ◽  
Systemic Administration ◽  
Molecular Signature ◽  
Postal Code ◽  
Organ Specific

Growth factors, chemokines and cytokines guide tissue regeneration after injuries. However, their applications as recombinant proteins are almost non-existent due to the difficulty of maintaining their bioactivity in the protease-rich milieu of injured tissues in humans. Safety concerns have ruled out their systemic administration. The vascular system provides a natural platform for circumvent the limitations of the local delivery of protein-based therapeutics. Tissue selectivity in drug accumulation can be obtained as organ-specific molecular signatures exist in the blood vessels in each tissue, essentially forming a postal code system (“vascular zip codes”) within the vasculature. These target-specific “vascular zip codes” can be exploited in regenerative medicine as the angiogenic blood vessels in the regenerating tissues have a unique molecular signature. The identification of vascular homing peptides capable of finding these unique “vascular zip codes” after their systemic administration provides an appealing opportunity for the target-specific delivery of therapeutics to tissue injuries. Therapeutic proteins can be “packaged” together with homing peptides by expressing them as multi-functional recombinant proteins. These multi-functional recombinant proteins provide an example how molecular engineering gives to a compound an ability to home to regenerating tissue and enhance its therapeutic potential. Regenerative medicine has been dominated by the locally applied therapeutic approaches despite these therapies are not moving to clinical medicine with success. There might be a time to change the paradigm towards systemically administered, target organ-specific therapeutic molecules in future drug discovery and development for regenerative medicine.

scholarly journals Low-intensity shock wave therapy for erectile dysfunction and the influence of disease duration

2019 ◽  
Vol 90 (4) ◽  
pp. 276-282 ◽  
Author(s):  
Pedro Simoes De Oliveira ◽  
Tiago Ribeiro De Oliveira ◽  
Álvaro Nunes ◽  
Francisco Martins ◽  
Tomé Lopes
Keyword(s):  
Shock Wave ◽  
Erectile Dysfunction ◽  
Prospective Study ◽  
Disease Duration ◽  
Peak Systolic Velocity ◽  
Shock Wave Therapy ◽  
Treatment Results ◽  
Open Label ◽  
Low Intensity ◽  
Diastolic Velocity

Objective: Low-intensity shock-wave treatment (LiSWT) is a therapy for erectile dysfunction (ED) with good results reported in the literature. The aim of this study was to evaluate the results of LiSWT on patients treated for ED and the influence of ED duration in treatment outcomes. Material and methods: We performed an open-label single-arm prospective study of patients treated with LiSWT for ED. Patients were assessed with the IIEF-5 at baseline and at six weeks and three months after LiSWT, and with penile dynamic Doppler ultrasound before treatment and six weeks after. Patients were divided into two groups accordingly to ED evolution time: ≤ 24 months and > 24 months. Results: Twenty-five patients were enrolled, 13 had ED ≤ 24 months and 12 > 24 months. Median baseline IIEF-5 was 14, at 6 weeks post LiSWT was 16 (p < 0.001) and at 3 months post LiSWT was 18 (p < 0.001). Mean baseline peak systolic velocity (PSV) was 29.3 ± 13.0 cm/s, after LiSWT was 35.9 ± 15.2 cm/s (p 0.001). Mean baseline end-diastolic velocity (EDV) was 2.6 ± 4.8 cm/s and after LiSWT was 1.3 ± 4.3 cm/s (p 0.015). No statistical significative difference was identified between the two groups. Conclusions: LiSWT is a safe, harmless and repeatable treatment tool for ED with good outcomes reported. Our results suggest that length of disease duration doesn´t negatively influences treatment results.

scholarly journals The Effect of Testosterone Replacement Therapy on Penile Hemodynamics in Hypogonadal Men With Erectile Dysfunction, Having Veno-Occlusive Dysfunction

2018 ◽  
Vol 12 (3) ◽  
pp. 634-638 ◽  
Author(s):  
Ozan Efesoy ◽  
Selahittin Çayan ◽  
Erdem Akbay
Keyword(s):  
Erectile Dysfunction ◽  
Replacement Therapy ◽  
Erectile Function ◽  
Peak Systolic Velocity ◽  
Resistive Index ◽  
Testosterone Replacement ◽  
Testosterone Replacement Therapy ◽  
Testosterone Levels ◽  
Diastolic Velocity ◽  
Physiological Serum

Hypogonadism may cause veno-occlusive dysfunction (VOD) by structural and biochemical alterations in the cavernosal tissue. The aim of the study was to investigate the effect of testosterone replacement therapy (TRT) on penile hemodynamics in hypogonadal men with erectile dysfunction and VOD. The study included 32 hypogonadal men with erectile dysfunction, having VOD. All patients underwent penile color Doppler ultrasonography (PCDU) at the beginning and 6 months after the initial evaluation. Erectile function was evaluated with the 5-item version of the International Index of Erectile Function (IIEF-5); hypogonadism was evaluated by testosterone measurement and the Aging Male Symptoms (AMS) scale. All patients received transdermal testosterone 50 mg/day for 6 months. Clinical and radiological findings were compared before and 6 months after the TRT. The mean age was 58.81 ± 4.56 (52–69) years. Mean total testosterone levels were 181.06 ± 39.84 ng/dL and 509.00 ± 105.57 ng/dL before and after the therapy, respectively ( p < .001). While all patients had physiological serum testosterone levels (>320 ng/dL) after the therapy, three cases (9.3%) had no clinical improvement of hypogonadism symptoms. Cavernosal artery peak systolic velocity (PSV) and resistive index (RI) significantly increased, and end diastolic velocity (EDV) significantly decreased after TRT. VOD no longer existed in 21 (65.6%) of the cases. This study demonstrated that TRT may restore penile hemodynamics in hypogonadal men with VOD.

scholarly journals Levels of agreement in the measurements of carotid artery ultrasound across a regional vascular network

Ultrasound ◽  
2018 ◽  
Vol 26 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Mervyn Alexander McKenna ◽  
Michelle Clare Bonfield ◽  
Teresa Robinson
Keyword(s):  
Carotid Artery ◽  
Internal Carotid Artery ◽  
Common Carotid Artery ◽  
Internal Carotid ◽  
Carotid Artery Disease ◽  
Imaging Modality ◽  
Peak Systolic Velocity ◽  
Vascular Network ◽  
Diastolic Velocity ◽  
Spectral Doppler

Introduction Duplex ultrasound is often the sole imaging modality used in diagnosing carotid artery disease. However, the reproducibility and repeatability of scientists in determining the peak systolic velocity and end diastolic velocity of the internal carotid artery and common carotid artery (CCA) is widely debated. Study aim To investigate intra- and inter-operator variability in diagnostic ultrasound of the carotid arteries across a centralised vascular network using a healthy test subject. To identify potential causes of variability and highlight areas for improvement. Methods Fifteen vascular scientists across four hospital Trusts in the Bristol, Bath and Weston vascular network measured the peak systolic velocity and end diastolic velocity of the internal carotid artery and common carotid artery in a subject using a single portable ultrasound machine. A double blind assessment of spectral Doppler images was performed by two vascular clinical scientists for optimal caliper placement, spectral gain and angle correction. Results were compared for intra- and inter-operator variability. Results Initial quality assessment of the Doppler images revealed that three out of 15 scientists produced suboptimal results. Box plot analysis of the common carotid artery and internal carotid artery for each scientist revealed significant variance (ANOVA p < 0.05). However, a Levene’s test revealed no single operator who consistently produced highly variable results ( p = 0.569). Conclusion This study highlights the difficulty in obtaining consistent velocity measurements from a subject. Despite the variability in absolute peak systolic velocity and end diastolic velocity, scientists were generally consistent in obtaining an optimal spectral Doppler trace. Some issues with consistency were, however, identified which were subsequently addressed.

195 Are the Spectral Doppler Indices of the Ovarian Arteries Predictive of Ovulatory Responses and Embryo Yields in Superovulated Ewes?

2018 ◽  
Vol 30 (1) ◽  
pp. 238
Author(s):  
M. E. F. Oliveira ◽  
Y. Tarasevych ◽  
W. R. R. Vicente ◽  
P. M. Bartlewski
Keyword(s):  
Resistance Index ◽  
Peak Systolic Velocity ◽  
Ovarian Response ◽  
Embryo Viability ◽  
Mean Velocity ◽  
Ovarian Artery ◽  
Diastolic Velocity ◽  
Spectral Doppler ◽  
Left And Right ◽  
Doppler Indices

Increased uterine and ovarian blood flow seems to be related to the effectiveness of ovarian response to hormonal superstimulation in mares (Witt et al. 2012 Theriogenology 77, 1406-1414). Similar studies do not exist for sheep. Nineteen Santa Inês ewes were subjected to a 9-day CIDR® priming and superovulatory (SOV) treatment with 200 mg of porcine (p)FSH per ewe given twice daily for 4 consecutive days in decreasing doses and initiated 6 days after CIDR® insertion. Ten ewes received an IM injection of oestradiol benzoate (EB, 350 μg) at the time of CIDR® insertion (group E); the remaining animals served as controls (group C). The ewes were placed in a pen with rams for 3 days after CIDR® removal. The embryos were recovered surgically 6 days after the CIDR® removal. Transrectal ultrasonographic examinations (Doppler mode) using MyLab VET 30 scanner (Esaote, Genoa, Italy) equipped with a linear-array (6- to 8-MHz) transducer were performed once a day throughout the SOV treatment (Days 1 to 4) to determine the velocimetric indices of the left and right ovarian arteries: flow velocity integral (FVI); peak systolic velocity (SVp); mean velocity (Vm); end-diastolic velocity (EDV); vascular resistance index [RI = (SVp – EDV)/SVp]; and pulsatility index [PI = (SVp – EDV)/Vm]. All spectral data were obtained from a longitudinal subovarian segment of the ovarian artery using a gate ranging from 2 to 3 mm (~two-thirds of the vessel’s diameter) and insonation angle ≤60°. There were no differences (P > 0.05) in ovarian responses and embryo yields/quality between left and right ovaries/uterine horns flashed or between EB-treated and control ewes. Mean EDV and Vm were greater (P < 0.05) in group C compared with group E on Days 1 and 2, and mean Vp was greater (P < 0.05) in group C ewes on Day 3 of the SOV treatment. In group E, there were 5 significant correlations between the spectral Doppler indices (RI, PI, and EDV) of the ovarian arteries recorded on Days 2 and 4 and SOV responses (numbers of degenerated embryos, unfertilized eggs, and luteinized unovulated follicles characterised by a lack of ovulatory stigmata). In group C, 7 significant correlations were found between Vp, EDV, Vm, and RI on Days 1, 2, and 3 and numbers/percentages of degenerated embryos, numbers of prematurely regressed luteal structures (pale, ≤5 mm in diameter), and embryo viability rates (percentage of transferrable quality embryos). When ultrasonographic and SOV data were analysed separately for the left and right ovarian artery/uterine horn, multiple significant correlations were found between the velocimetric indices and SOV responses but they varied among days, the 2 ovaries, and the 2 groups of animals studied. These results may be interpreted to suggest that intrinsic gonadal factors remain a significant barrier precluding the prediction of SOV outcomes from haemodynamic changes in ovine ovarian arteries. Velocimetric indices determined in the ovarian arteries appear to have limited prognostic value during the application of different SOV protocols in ewes.

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