The Relationship of Carotid Plaque, Intima Media Thickness (IMT), Resistivity Index (RI) and Pulsatility Index(PI) in Asian-Indian Patients with Acute Ischemic Stroke with and without Type2 DM

Aim: To determine the relationship of carotid plaque, intima media thickness (IMT), resistivity index (RI) and pulsatility index (PI) and prevalence of different risk factors with acute ischemic stroke and stroke subtypes in both diabetic and non-diabetic subjects. Materials and methods: 80 cases of acute ischemic strokes and 40 healthy controls were included in the study. The plaque, IMT, RI and PI were measured by carotid duplex ultrasound. Results: 31 subjects were Type 2 diabetic, 54 hypertensive while 25 were both diabetic and hypertensive. 23 cases (28.75%) had lacunar stroke (LACI), 32 (40%) stroke involving partial anterior circulation(PACI), 10(12.5%) stroke in posterior circulation (PACI) and 15(18.75%) stroke involving total anterior circulation(TACI) respectively. The mean IMT (0.88 ± 0.19mm), RI(0.76 ± 0.05) and PI(1.71 ± 0.19) of patients and mean IMT (0.6±0.09mm), RI (0.61 ± 0.06) and PI (1.53 ± 0.11) of controls were statistically significant (p-0.000). The mean values of IMT, PI and RI were significantly higher in diabetics (IMT-0.90 ± 0.16 VS 0.64 ± 0.11, p-0.013;PI-1.76 ± 0.20 VS 1.49 ± 0.09, P-0.000 and RI-0.76 ± 0.04 VS 0.59 ± 0.06, P-0.000) and similarly the mean values for IMT, PI and RI in hypertensives as compared to controls (IMT-0.88 ± 0.16 vs 0.65 ± 0.10, P-0.006;PI1.69 ± 0.18 vs 1.49 ± 0.09, P-0.000 and RI 0.76 ± 0.04 vs 0.59 ± 0.06, P-0.000). The mean IMT, PI and RI were increased significantly in smokers compared to controls (IMT-0.93 ± 0.20 vs 0.63 ± 0.06, P-0.000;PI-1.82 ± 0.22 vs 1.49 ± 0.09, P-0.000 and RI-0.77 ± 0.04 vs 0.59 ± 0.06, P-0.000). Type 3 plaque accounted for 27 (56.2%) cases and Type 2 plaque 12 (25%) cases. The total number of plaques in patients as compared to controls were significantly more (P-0.0034) and the mean plaque area was 46 mm2 for cases and 20 mm2 for control (P-0.0001). TACI was the most common type of ischemic stroke seen in DM (60%), HTN (66.6%) and smokers (66.7%). Plaques (73.3%), IMT (0.90 ± 0.12), PI(1.72 ± 0.14) and RI (0.76 ± 0.13) were more commonly associated with TACI subtype. On multivariate analysis using ANOVA, the mean PI was highly significant (0.000) in relation to types of plaque. Summary and Conclusions: IMT, RI, PI and plaque type are useful diagnostic parameters for acute ischemic stroke and its subtypes. They can be used as noninvasive tools for predicting and preventing ischemic stroke in smokers as well as subjects with DM and hypertension.

Parathyroid hormone pulsatility: physiological and clinical aspects

Parathyroid hormone （PTH） secretion is characterized by an ultradian rhythm with tonic and pulsatile components. In healthy subjects, the majority of PTH is secreted in tonic fashion, whereas approximately 30% is secreted in low-amplitude and high-frequency bursts occurring every 10-20 min, superimposed on tonic secretion. Changes in the ultradian PTH secretion were shown to occur in patients with primary and secondary osteoporosis, with skeletal effects depending on the reciprocal modifications of pulsatile and tonic components. Indeed, pathophysiology of spontaneous PTH secretion remains an area potentially suitable to be explored, particularly in those conditions such as secondary forms of osteoporosis, in which conventional biochemical and densitometric parameters may not always give reliable diagnostic and therapeutic indications. This review will highlight the literature data supporting the hypothesis that changes of ultradian PTH secretion may be correlated with skeletal fragility in primary and secondary osteoporosis.

Local dose-dense chemotherapy for triple-negative breast cancer via minimally invasive implantation of 3D printed devices

Dose-dense chemotherapy is the preferred first-line therapy for triple-negative breast cancer(TNBC),a highly aggressive disease with a poor prognosis.This treatment uses the same drug doses as conventional chemotherapy but with shorter dosing intervals,allowing for promising clinical outcomes with intensive treatment.However,the frequent systemic administration used for this treatment results in systemic toxicity and low patient compliance,limiting therapeutic efficacy and clinical benefit.Here,we report local dose-dense chemotherapy to treat TNBC by implanting 3D printed devices with timeprogrammed pulsatile release profiles.The implantable device can control the time between drug releases based on its internal microstructure design,which can be used to control dose density.The device is made of biodegradable materials for clinical convenience and designed for minimally invasive implantation via a trocar.Dose density variation of local chemotherapy using programmable release enhances anti-cancer effects in vitro and in vivo.Under the same dose density conditions,device-based chemotherapy shows a higher anticancer effect and less toxic response than intratumoral injection.We demonstrate local chemotherapy utilizing the implantable device that simulates the drug dose,number of releases,and treatment duration of the dose-dense AC(doxorubicin and cyclophosphamide)regimen preferred for TNBC treatment.Dose density modulation inhibits tumor growth,metastasis,and the expression of drug resistance-related proteins,including p-glycoprotein and breast cancer resistance protein.To the best of our knowledge,local dose-dense chemotherapy has not been reported,and our strategy can be expected to be utilized as a novel alternative to conventional therapies and improve anti-cancer efficiency.

Comparison of Ultrasound Blood Flow Characteristics of the Lower Limb in Diabetics with Early-Stage Peripheral Artery Disease and Non-Diabetic Controls

The aim of this study was to compare lower limb blood flow in asymptomatic diabetic patients with early-stage peripheral artery disease (PAD) and non-diabetic controls using duplex ultrasound parameters. This was a comparative cohort study of lower limb blood flow in 35 Black-African diabetic patients (25 females and 10 males with early-stage PAD median age 54 [IQR, 47 - 61] years;median HbA1c 6.3 [IQR, 5.7 - 8.0]%;BMI 29.2 ± 6.7;ABI 1.1 ± 0.1) and 36 non-diabetic controls (28 females and 8 males;median age 54 [IQR, 47 - 61] years;median HbA1c 6.3 [IQR, 5.7 - 8.0] %, BMI 29.2 ± 6.7;ABI 1.1 ± 0.1). Peak systolic velocity (PSV), pulsatility index (PI) and resistive index (RI), were utilised to compare blood flow in the popliteal arteries (PA), anterior tibial arteries (ATA) and posterior tibial arteries (PTA) in addition to ankle brachial index. All the ultrasound parameters showed good (ICC ≥ 0.7;0.50 - 0.85, 95% CI) to excellent (ICC = 1.0;1.0 - 1.0, 95% CI) reliability within groups as well as acceptable variability () other than pulsatility index of the anterior tibial artery within diabetic patients (11.1% CV). PSV, RI and PI were significantly and meaningfully higher (P;d ≥ 0.33), in diabetic patients compared to non-diabetic controls except for PI - PTA (P = 0.72;d = 0.11). Differences in PSV and RI highlighted the effects of early-stage PAD on lower limb blood flow of diabetic patients. In contrast, the effects of early-stage PAD on blood flow were not demonstrated in the PTA and ATA of diabetic patients by PI.

Analytical study of pulsatile mixed electroosmotic and shear-driven flow in a microchannel with a slip-dependent zeta potential

The escalation of zeta potential by the influence of wall slip for the electrokinetically modulated flow through a microchannel motivates to consider the impact of hydrodynamic slippage upon the zeta or surface potential.The reported study undergoes an analytical exploration of the pulsatile electroosmosis and shear-actuated flow characteristics of a fluid with a Newtonian model through a microchannel with parallel plates by invoking the reliance of a zeta or surface potential on slippage.The linearized Poisson-Boltzmann and momentum equations are solved analytically to obtain the explicit expression of the electrical potential induced in the electrical double layer(EDL),the flow velocity field,and the volumetric flow rate for an extensive span of parameters.The velocity field proximal to the microchannel wall is observed to enhance by an apparent zeta potential,and is further escalated for a thinner EDL and an oscillating electric field with a higher amplitude.However,near the core region of the microchannel,the flow velocity becomes invariant with the EDL thickness.The result shows that the lower wall velocity contributes to the flow velocity along with the electroosmotic body force and the impact of the velocity of the wall underneath diminishes proximal to the upper wall.Moreover,the volumetric flow rate increases when the thickness of the EDL decreases,owing to the influence of the wall slip.However,for thinner EDLs and medium and higher oscillating Reynolds numbers,the volumetric flow rate varies non-monotonously,correlative to the slip-free and slip cases.

Analysis of Etiology,Diagnosis,and Treatment Strategy and Efficacy of Pulsatile Tinnitus Caused by Abnormal Vascular Anatomy

Objective To investigate the etiology,clinical characteristics,diagnosis,and treatment strategies and efficacy of pulsatile tinnitus(PT)caused by vascular anatomy abnormality.Methods The clinical data of 45 patients with PT in our hospital from 2012 to 2019 were collected and retrospectively analyzed.Results All 45 patients had vascular anatomical abnormalities.The patients were divided into 10 categories according to the different locations of vascular abnormalities:sigmoid sinus diverticulum(SSD),sigmoid sinus wall dehiscence(SSWD),SSWD with high jugular bulb,pure dilated mastoid emissary vein,aberrant internal carotid artery(ICA)in the middle ear,transverse-sigmoid sinus(TSS)transition stenosis,TSS transition stenosis with SSD,persistent occipital sinus stenosis,petrous segment stenosis of ICA,and dural arteriovenous fistula.All patients complained of PT synchronous with heartbeat rhythm.Endovascular interventional therapy and extravascular open surgery were used according to the location of the vascular lesions.Tinnitus disappeared in 41 patients,was significantly relieved in 3 patients,and was unchanged in 1 patient postoperatively.Except for one patient with transient headache postoperatively,no obvious complications occurred.Conclusion PT caused by vascular anatomy abnormalities can be identified by detailed medical history and physical and imaging examination.PT can be relieved or even completely alleviated after appropriate surgical treatments.

Surgical treatment of pulsatile tinnitus related to the sigmoid sinus

Objective: Tinnitus-a common clinical symptom-can be categorized into pulsatile tinnitus(PT) and non-PT. Among these, PT is usually associated with sigmoid sinus symptoms, such as sigmoid sinus wall defect or diverticulum, for which various surgical treatments are available. We have discussed the clinical efficacy of surgery for sigmoid sinus-associated PT via the transmastoid approach in this study.Methods: We conducted a retrospective review of 4 patients who underwent surgery for sigmoid sinusassociated PT via the transmastoid approach at Nanjing Drum Tower Hospital from January to December2020. Of these, 2 patients had sigmoid sinus wall defect and 2 had sigmoid sinus diverticulum. Postoperative tinnitus grading and surgical efficacy were determined.Results: After surgery, PT dissolved in 3 patients, while tinnitus significantly decreased in 1 patient.During the follow-up period of 12-18 months, none of the 4 patients showed complications related to increased intracranial pressure or venous sinus thrombosis, and tinnitus symptoms disappeared in 3patients without recurrence, although 1 patient occasionally developed tinnitus. Postoperative thin-slice CTA of the temporal bone indicated that the sigmoid sinus bone wall defect or diverticulum was completely repaired with a thick soft tissue coverage.Conclusion: Surgical repair of sigmoid sinus-associated PT via the transmastoid approach deserves clinical promotion as it exhibited better efficiency while being relatively less invasive.

Fatal Cataclysmic Otorrhagia and Epistaxis Due to a Ruptured Aneurysm of the Petrous Internal Carotid Artery: A Case Report

Background: Aneurysms of the internal carotid artery within the petrous temporal bone are extremely rare;their true incidence is unknown. The exact cause is unclear: they may be congenital or result from trauma, infection, or radiation. Aim: We report a case of massive otorrhagia and epistaxis from a ruptured aneurysm of the petrous internal carotid artery. Case Presentation: A 34-year-old man presented to our department for the first time with repeated left otorrhagia ongoing for 5 years, left sided pulsatile tinnitus and left conductive hearing loss. In his history, we noted a right hemi-corporeal deficit of sudden onset one month ago and the head-CT showed a left frontoparietal subarachnoid hemorrhage without any visualised vascular malformation. Otomicroscopy showed a pulsatile mass visible at the posterior part of the hypotympanum. There was a right-sided hemiparesis estimated at 2/5 with no disorder of the sensitivity. After hemodynamic stabilization, the patient was discharged from the hospital and treatment was scheduled in interventional radiology and neurosurgery unit. Unfortunately the patient presented at home with a cataclysmic hemorrhage by massive otorrhagia and epistaxis and arrived dead at the emergency unit. Conclusion: The treatment of a petrous carotid aneurysm must be carried out quickly considering the risk of rupture leading to a cataclysmic hemorrhage that can be rapidly life threatening.

The Study of Ovarian Artery Hemodynamics in Patients with Infertility by Color Doppler Energy

Seventy four cases of infertility were examined to study the hemodynamics of the bilateral ovarian arteries at 21st day during the corpus luteum phase by color Doppler energy(CDE) and color Doppler flow imaging (CDFI). All the patients were verified by laparoscopy, fallopian tube patency examination and ovarian function test. Twenty two healthy women served as controls. The results showed that the difference of resistance index(RI)and pulsatility index (PI) of bilateral ovarian arteries between the infertility and the normal controls had statistical significance ( P <0.01), and the PI showed negative correlation with the thickness of endometrium (left side: r =0.724, P <0.01; right side: r =0.756, P <0.01). The results also showed that CDE was more sensitive than CDFI in displaying the ovarian arteries. It could be concluded that the elevated resistance of ovarian artery during the corpus luteum phase was one of the important factors that resulted in infertility.

脉冲式静脉注射促黄体激素释放激素对不孕症促排卵的疗效观察

自八十年代初开始,采用脉冲式促黄体激素释放激素(LHRH)诱导排卵,迄今已有许多成功的报道。Asch[1]作了统计,这种疗法的排卵周期率为90％,妊娠周期率为30～15％。国内于1973年人工合成了LHRH并已生产自动注射泵,脉冲式给药方法的应用在国内亦正方兴未艾。本研究采用LHRH脉冲式静脉给药方法,旨在探讨各种内分泌原因所致大孕症对LHRH脉冲治疗的反应性,为LHRH广泛用于临床提供实践基础。

从早期大脑血流量的变化评估活血化瘀中药对缺血性中风预后的影响

对初次因中大脑动脉灌注区缺血性中风的病人,在中风后的72小时内及7天后,分别使用穿颅超音波仪器(Transcranial Doppler,TCD),评估其收缩血流速度(systolic Blood Flow Velocity,Vsys．)、平均血流速度(Mean Blood Flow Velocity,Vmean)、搏动性指数(Pulsatility Index,PI)及阻力性指数(Resistance Index．RI)的改变,评估在72小时内即使用“活血化瘀”中药的病人,预后的影响。结果发现,早期即使用“活血化瘀”中药的病人,相对于未使用者,其大脑血流量有较好的改善,三个月后的神经功能恢复也有较好结果。我们认为“活血化瘀”的中药,因安全性高,可积极地推广使用,以填补tPA在急性中风使用之不足处,并且早期使用穿颅超音波仪器(TCD)评估大脑缺血性中风病患的血液动力改变的情况,可作为往后神经功能恢复的预测。

Testicular vascularization at two locations in relation to hormonal levels,and pixel echotexture in bulls at different ages

Objective:To assess the hemodynamic changes that occurred in the main testicular artery at two different locations such as supra and marginal ones in bulls at three different ages.Methods:Eighteen Baladi bulls were divided according to their age into three different age groups:1 year[n=6;groupⅠwith bodyweight(380±10)kg],3 years[n=6;groupⅡwith bodyweight(570±10)kg],and 6 years old[n=6;groupⅢwith bodyweight(650±10)kg]Baladi bulls.Circumference of the scrotum,thickness of the mediastinum,testicular dimensions,vascularity,and hormonal levels were measured.Testicular hemodynamics were assessed by Doppler ultrasound scanning.Results:Testicular width,length,and volume were significantly different among the three age groups,with the highest in bulls of groupⅢ(P<0.05).The bulls in groupⅢhad significantly higher mediastinal line thickness and scrotal circumference than groupⅠ(P<0.05),but there was no significant difference between groupⅡand groupⅢ.Bulls in groupⅡshowed a decline in Doppler indices(resistance and pulsatility indexes)at both testicular branches compared to the other two groups(P<0.05).Supra and marginal end diastolic velocities in the three age groups were significantly different,with the highest in groupⅡ(P<0.05).Time average velocity(cm/s)was significantly elevated in groupⅡcompared to the other two groups(P<0.05).Both testicular echotextures were significantly decreased in groupⅡ(P<0.05).Estradiol and nitric oxide metabolites were significantly high in groupⅡcompared to the other two groups(P<0.05).Meanwhile,the level of plasma testosterone was maximum in groupⅢ(P<0.05).Positive correlations were found between supratesticular artery resistance and pulsatility indexes(r=0.81;P<0.001),while both resistance and pulsatility indexes had correlated negative with estradiol(r=-0.71 and r=-0.91;P<0.001),and nitric oxide metabolites(r=-0.92 and r=-0.72;P<0.001).Conclusions:Three-year old Baladi bull has the lesser Doppler indices with lesser echotexture and greater nitric oxide with estradiol concentrations,which directs a significant ability for the thermoregulation process.These parameters will help in breeding selection.

EFFECTS OF HIGH-DENSITY CURRENT PULSES ON WORK HARDENING BEHAVIORS OF AUSTENITE STAINLESS STEEL IN WIRE-DRAWING DEFORMATION

The influence of high-density pulsing current on the work-hardening behaviour of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ=κΕn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.

Rotational Swashplate Pulse Continuously Variable Transmission Based on Helical Gear Axial Meshing Transmission

The current research on pulse continuously variable transmission（CVT） is mainly focused on reducing the pulse degree and making pulse degrees a constant value. Current research mainly confined to find out new design parameters by using the method of optimization, and reduce the pulse degree of pulse CVT and its range of variation. But the fact is that the reduction of the pulse degree is not significant. This article presents a new structure of mechanical pulse CVT--the rotational swashplate pulse CVT with driven by helical gear axial meshing. This transmission is simple and compact in structure and low in pulsatile rate （it adopts 6 guide rods）, and the pulsatile degree is irrelevant to the transmission ratio. Theoretically, pulsatile rate could be reduced to zero if appropriate curved surface of the swashplate is used. Compared with the connecting rod pulse CVT, the present struc^tre uses helical gear mechanism as transmission part and it avoids unbalanced inertial force in the former model. This paper analyzes the principle of driving of this transmission, presents its mechanical structure, and discusses its motion characteristics. Experimental prototype of this type of CVT has been manufactured. Tests for the transmission efficiency（when the rotational speed of the output shaft is the maximum） and the angular velocity of the output shaft have been carried out, and data have been analyzed. The experimental results show that the speed of the output shaft for the experimental prototype is slightly lower than the theoretical value, and the transmission efficiency of the experimental prototype is about 70%. The pulse degree of the CVT discussed in this paper is less than the existing pulse CVT of other types, and it is irrelevant to the transmission ratio of the CVT. The research provides the new idea to the CVT study.

Effects of renal artery stenosis on realistic model of abdominalaorta and renal arteries incorporating fluid-structureinteraction and pulsatile non-Newtonian blood flow

The effects of the renal artery stenosis （RAS） on the blood flow and vessel walls are investigated. The pulsatile blood flow through an anatomically realistic model of the abdominal aorta and renal arteries reconstructed from CT-scan images is simulated, which incorporates the fluid-structure interaction （FSI）. In addition to the investigation of the RAS effects on the wall shear stress and the displacement of the vessel wall, it is determined that the RAS leads to decrease in the renal mass flow. This may cause the activation of the renin-angiotension system and results in severe hypertension.

Experimental and numerical study of the effect of pulsatile flow on wall displacement oscillation in a flexible lateral aneurysm model

This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneurysm model was developed,and a self-designed piston pump was used to provide the pulsatile flow conditions.A fluid-structure interaction simulation was applied for comparison with and analysis of experimental findings.The maximum wall displacement oscillation increased as the pulsation frequency and outflow resistance increased,especially at the aneurysm dome.There is an obvious circular motion of the vortex center accompanying the periodic inflow fluctuation,and the pressure at the aneurysm dome at peak flow increased as the pulsatile flow frequency and terminal flow resistance increased.These results could explain why abnormal blood flow with high frequency and high outflow resistance is one of the risk factors for aneurysm rupture.

Diploic vein as a newly treatable cause of pulsatile tinnitus: A case report

BACKGROUND Pulsatile tinnitus(PT)is an annoying sound that can be eliminated with targeted treatment of the cause.However,the causes of PT have not been fully elucidated.CASE SUMMARY A 38-year-old woman with right-sided objective PT underwent preoperative computed tomography arteriography and venography(CTA/V).A 3.8 mm vine diploic vein(DV),which passed through the mastoid air cells posteriorly in a dehiscent canal and was continuous with the transverse-sigmoid sinus,was thought to be the causative finding.Four-dimensional flow magnetic resonance(4D flow MR)imaging showed that the blood in the DV flowed toward the transverse-sigmoid sinus.The closer the blood was to the transverse-sigmoid sinus,the higher the velocity.No vortex or turbulence was found in the DV or adjacent transverse sinus.The sound was eliminated immediately after ligation of the DV with no recurrence during a three-month follow-up.No flow signal of the DV was noted on postoperative 4D flow MR.CONCLUSION A DV may be a treatable cause of PT.CTA/V and 4D flow MR could be utilized to determine the morphological and hemodynamic characteristics of the DV.

Bone remodeling in sigmoid sinus diverticulum after stenting for transverse sinus stenosis in pulsatile tinnitus: A case report

BACKGROUND Pulsatile tinnitus(PT)is a potentially disabling symptom that has received increasing attention.Multiple causes of PT have been confirmed by targeted treatment.However,dynamic changes of related structures in PT patients with multiple causes after stenting for ipsilateral transverse sinus stenosis(TSS)have not been previously reported.We report such a case and present postoperative computed tomography venography(CTV)follow-up findings to demonstrate the decreased sigmoid sinus diverticulum and bone remodeling.CASE SUMMARY A 45-year-old man suffered from left-sided PT for 15 years that was occasionally accompanied by headache and dizziness.Pre-operative CTV revealed left-sided sigmoid sinus wall anomalies(SSWAs),TSS,outflow dominance,large posterior condylar emissary vein,and an empty sella turcica.A cerebrospinal fluid pressure of 270 mmH2O was further detected.The sound disappeared immediately after stenting for ipsilateral TSS,with no recurrence during 2 years of follow-up.After the procedure,the patient underwent four consecutive CTV examinations.The diverticulum decreased 6 mo after the procedure with new bone remodeling.The density of the remodeled bone was further increased 1 year later,and a hardened edge was formed 2 years later.CONCLUSION PT associated with SSWAs,TSS,and idiopathic intracranial hypertension can be cured by stenting for TSS alone.And bone remodeling around SSWAs is a more significant finding.

Hydrodynamics of a Newly China-Made Jiuling Bileaflet Heart Valve Prostheses

Jiuling bileaflet prosthetic heart valve is manufactured in compliance with the national standard of P.R.C. GB12279 90. This mechanical heart valve substitute is constructed entirely of solid low temperature pyrolytic carbon. There is no graphite substrate within the leaflets or orifice. This prosthesis presents with satisfactory histocompatibility and induces little hemocoagulation around it. Objective: This study aimed to assess the hydrodynamic function of the newly China made Jiuling bileaflet heart valve prostheses. Methods: Jiuling valve has been tested in a pulsatile flow simulator in the aortic position. The testing condition was set at the pulsatile frequency of 55, 75, and 100 beats/min and a constant cardiac output of 4 L/min. The mean pressure differences, leakage volumes and closing volumes across each valve, and the effective orifice areas have been analyzed. Results: The Jiuling heart valves prosthesis had the lowest pressure difference at any given tissue annulus diameter. The mean pressure difference of all the Jiuling valves decreases with increasing the tissue annulus diameter or pulse frequency, and is in the range of below 10 mmHg. CarboMedics (CarboMedics, Inc., Austin, Tex.) is similar to that of the 21 mm and 23 mm Jiuling heart valves at the given pulse rate under 4 L/min. C L tilting disc valve (Lanzhou CarboMedics Inc., China) is similar to that of the 23 mm Jiuling heart valve. The effective orifice area of the Jiuling mechanical valve increases with increasing the tissue annulus diameter or pulse frequency. CarboMedics and C L tilting disc valve is similar to that of the 21 mm and 23 mm Jiuling heart valves. The Closing volume of the Jiuling prosthetic cardiac valves increases with increasing the tissue annulus diameter, but decreases with increasing the pulse frequency, and is in the range of below 11% (normalized by stroke volume). CarboMedics is below 16.5% of stroke volume; and C L tilting disc valve is below 7.5%. The leakage volume of the Jiuling prosthetic cardiac valves increases with increasing the tissue annulus diameter, but decreases with increasing the pulse frequency, and are in the range of below 28.9% (normalized by stroke volume). The leakage volume of CarboMedics is higher than that of the same sized 25 mm Jiuling valve, and the C L tilting disc valve is also higher than that of Jiuling valve at 4 L/min. Conclusion: For a given tissue diameter, the Jiuling valve showed significantly better hemodynamic characteristics. The material used in the construction is biocompatible, durable, and thromboresistant. The design permits light weight, low profile, and high ratio of flow area to tissue annulus diameter.

3D CFD Simulation of Pulsatile Blood Flow in the Human Aorta

A three-dimensional computational fluid dynamics (CFD) simulation of the physiological pulsatile blood flow in the human aortic arch and its three branches has been conducted by using commercial software StarCD. The blood flow, of a peak Reynolds number of 3289 and a Womersley parameter of 16.44, was simulated in a rigid aorta geometry that was built by computer aided design (CAD) reconstruction method based on autopsy data of a female adult. The purpose of this work is to further the understanding of the complex nature of aorta flow, therefore it mainly focuses on analysis of the spatial and temporal distributions of velocities and wall shear stresses. The results, illustrated by 3D visualization pictures and 2D graphs of the primary velocity profiles, wall shear stress and pressure distributions, as well as the secondary flow patterns, are in good agreement with those of other experimental and computational works. The distributions of pressure and wall shear stress support the correlation between high and low shear stresses and pressures and the atherosclerotic lesions.