One of the main causes of long-term failure of ePTFE grafts is the development of anastomotic intimal hyperplasia which leads to graft thrombosis. Experimental studies with bypass grafts have shown an inverse relationship between mean wall shear stress and intimal hyperplasia. The geometry of the anastomosis has a strong influence ...

Complications arising from gastrointestinal anastomosis failures are a major source of morbidity and mortality. This review examines the effects of local blood flow on anastomotic healing, and discusses strategies for improving perfusion. Disruption of blood supply plays a significant role in the development of anastomotic leakage. Several methods have been ...

Sequential grafting technique is adopted when one or more of the coronary arteries are blocked or severely narrowed. The objective of this study was to understand the influence of the anastomosis configuration on the blood flow in the three-dimensional coronary artery bypass graft (CABG) model. The finite volume technique was ...

BACKGROUND: There is still controversy about which vasodilator solution is best for storing radial artery (RA) conduits prior to coronary artery bypass grafting. The aim of this pilot study was to investigate how 4 different topical vasodilators applied during RA harvesting affect blood flow with the vessel in situ. MATERIALS ...

In order to evaluate the left internal thoracic artery flow pattern, when the vessel is used as a graft to supply the left coronary artery system, we evaluated flow by Doppler measurement, both at rest and under dobutamine stress. There were 2 groups of 20 patients each: group A patients ...

The recombinant form of the endogenous anticoagulant, tissue factor pathway inhibitor (rTFPI), is a potent inhibitor of Factor Xa (FXa) and the tissue factor-factor VIIa (TF:VIIa) complex. Surface-immobilized rTFPI reduces the thrombogenicity and intimal hyperplasia associated with synthetic vascular grafts in animal models and specifically reduces fibrin deposition on collagen-impregnated ...

In this paper, we report on the unsteady state modeling of blood flow in an end-to-side anastomosed bypass graft, which has a stenosis upstream from the junction. In coronary artery bypass grafting/surgery (CABG), new arteries are created in order to provide blood to the heart using other blood vessels as ...

The graft-host diameter ratios have impacts on the flow patterns of bypass graft. In order to clarify the influence of graft-host diameter ratios on the flow patterns and the wall shear stress in coronary artery bypass graft (CABG), the pulsatile blood flows in three CABG models, with the graft diameter ...

We investigated shunt murmurs based on wavelet transform analysis as a new method for assessing vascular access function. In the present study, in patients with venous stenosis near an arteriovenous fistula (A-V fistula), a sensor was placed at different positions around the stenosis and shunt murmur signals obtained using a ...

OBJECTIVE: The purpose of this study was to assess the pelvic circulation during endovascular abdominal aortic aneurysm repair (EVAR) with a new monitoring system measuring penile and buttock blood flow. METHODS: We measured penile brachial pressure index (PBI) during EVAR by pulse-volume-plethysmography (form PWV/ABItrade mark). We also measured bilateral gluteal ...

The long-term patency rate of peripheral artery bypass grafts remains low. Several theories exist which attempt to explain the disease forming mechanisms at the disease prone distal junction of the bypass graft. Common to these theories is that abnormal hemodynamics and wall mechanics contribute to the development of disease at ...

We consider the effect of geometrical configuration on the steady flow field of representative geometries from an in vivo anatomical data set of end-to-side distal anastomoses constructed as part of a peripheral bypass graft. Using a geometrical classification technique, we select the anastomoses of three representative patients according to the ...

OBJECTIVE: We investigated the clinical usefulness of thyroid blood-flow measurement in predicting relapse of Graves' disease (GD) in comparison with known risk factors for GD relapse. MEASUREMENT: Thyroid blood flow was measured in pulsed Doppler mode at the inferior thyroid artery (ITA), and the peak systolic velocity (PSV) calculated. PATIENTS: ...

Arteriovenous (AV) grafts and fistulas used for hemodialysis frequently develop intimal hyperplasia (IH) at the venous anastomosis of the graft, leading to flow-limiting stenosis, and ultimately to graft failure due to thrombosis. Although the high AV access blood flow has been implicated in the pathogenesis of graft stenosis, the potential ...

OBJECTIVE: Prosthetic femoral-popliteal bypasses are performed by using an end-to-side anastomosis, and disease can develop at the distal end; this can lead to poor long-term patency rates. Disturbed flow characteristics are hypothesized as being a major factor in promoting disease development. The objective of this study was to propose a ...

BACKGROUND: Inappropriate harvesting of arterial conduits can lead to severe postoperative complications. We analyzed clinical and functional results of patients undergoing radial artery (RA) harvesting by means of three techniques. METHODS: From January 2001 to January 2004 188 patients undergoing coronary artery bypass graft with RA were divided into three ...

The potential use of plasmin-treated fibrin-coated vascular prosthesis (PF-V) for coronary artery bypass grafting (CABG) in animal models was investigated. PF-V grafts, 3 mm in internal diameter, were studied on 5 sheep in off-pump CABG model and on 18 rabbits in abdominal aortic bypass grafting (AABG) model. Patency, blood flow, ...

Polymer biostability is one of the critical parameters by which these materials are selected for use as biomedical devices. This is the major rationale for the use of polymers which are highly crystalline and stiff namely expanded polytetrafluoroethylene (ePTFE) and Dacron in particular, as arterial bypass grafts. While this is ...

Pancreas graft thrombosis continues to be a major cause of graft loss. The removal of the donor spleen is accompanied by a significant reduction in pancreas graft blood flow. It is likely that reduced blood flow contributes to thrombosis in concert with other factors. We present a case of simultaneous ...

OBJECTIVE: To investigate the surgical treatment methods and evaluate the outcome of gunshot wounds combining with seawater immersion in rabbits' femoral arteries. METHODS: One hundred healthy New Zealand white rabbits (either sex, 3.14 kg+/-0.61 kg in weight) were randomly divided into a seawater immersion group (n=50) and a simple injury ...

Haemodynamics was widely believed to correlate with anastomosis restenosis. Utilizing the haemodynamic parameters as indicator functions, distal anastomosis was redesigned by some researchers so as to improve the long-term graft patency rate. However, there were few studies upon the proximal anastomosis. Therefore, in this study, flow characteristics and distributions of ...

BACKGROUND: We assessed the validity of intraoperative transit time flow measurement (TTFM) in predicting graft flow abnormalities. METHODS: Intraoperative graft flow measurement using TTFM and early postoperative coronary angiography was performed in 58 patients who underwent total arterial off-pump coronary artery bypass. Five variables (flow pattern, mean flow, pulsatility index, ...

Non-Newtonian fluid flow in a stenosed coronary bypass is investigated numerically using the Carreau-Yasuda model for the shear thinning behavior of the blood. End-to-side coronary bypass anastomosis is considered in a simplified model geometry where the host coronary artery has a 75% severity stenosis. Different locations of the bypass graft ...

Although continuous flow (CF) and pulsatile flow (PF) ventricular assist devices (VADs) are being clinically used, their effects on aortic blood flow, as a measure of overall blood distribution, remain unclear. In acute VAD support animal experiments, our group has described a zone of turbulent mixing in the aortic arch. ...

PURPOSE: To use an in vitro flow model to investigate the flow patterns in a bifurcated stent-graft for abdominal aortic aneurysm (AAA) repair. METHODS: Experiments were performed in an in vitro test rig incorporating a simplified non-planar model of an AAA. A two-component bifurcated device consisting of a stent structure ...

AIMS: Patients undergoing infrainguinal arterial reconstruction using vein conduits, frequently undergo intra-operative Doppler flow measurements to determine technical adequacy. The aim of this study was to determine the proportion of vein grafts with normal intra-operative haemodynamic parameters that were subsequently discovered to be 'at risk' on post-operative duplex surveillance scanning. ...

Saphenous vein (SV) interposition grafts are often used for high-flow extracranial-intracranial bypass procedures. During these procedures, it is essential to remove air and debris from the graft and to evaluate blood flow through the graft after it has been anastomosed to other cortical vessels. In this paper, the authors describe ...

Polymers such as Dacron and polytetrafluoroethylene (PTFE) have been used in high flow states with relative success but with limited application at lower flow states. Newer polymers with greater compliance, biomimicry, and ability to evolve into hybrid prostheses, suitable as smaller vessels, are now being introduced. In view of the ...

BACKGROUND: Native flow competition is a significant factor affecting bypass graft patency. The objective of this study was to compare the effect of competitive flow on conduit flow dynamics in the gastroepiploic artery (GEA) and the saphenous vein graft (SVG). METHODS: In 51 patents, 23 GEAs (in-situ grafts) and 28 ...

BACKGROUND: Screening of progenitor cell grafts (marrow, peripheral blood, and cord blood) for microbial contamination is required by the standards of AABB. Clinical sequelae from infusion of these contaminated grafts, however, is uncommon. STUDY DESIGN AND METHODS: A retrospective analysis of 735 consecutive marrow and peripheral blood progenitor cell harvests ...

OBJECTIVE: We sought to expand our assessment of calcium alginate as an embolic agent in an animal model of a cerebral arteriovenous malformation (AVM). The objective of this study was to assess the long-term biocompatibility and stability of calcium alginate in AVM swine models that survived from 1 to 6 ...

OBJECTIVE: The aim of the present study was to assess the effect of an adjuvant av-fistula on prosthetic bypass grafting and whether intraoperative flow measurements could predict patency and adverse events of cuffed femorocrural PTFE bypass with or without an av-fistula. METHODS: A total of 50 patients in need of ...

Bypass graft failures have been attributed to various hemodynamic factors, including flow stasis and low shear stress. Ideally, surgeries would minimize the occurrence of these detrimental flow conditions, but surgeons cannot currently assess this. Numerical simulation techniques have been proposed as one method for predicting changes in flow distributions and ...

This study was concerned with investigating the influence of mechanical factors on the hemodynamics of the end-to-side anastomosis in an attempt to identify critical factors and establish if it is possible to re-engineer existing, patient-specific, by-pass grafts with a view to increasing their patency. The study chose the femoral artery ...

The failure of the vascular anastmoses is a devastating complication in free jejunum transplantation. We used color Doppler sonography to estimate blood flow in free jejunal grafts in 21 patients who underwent radical pharyngoesophagectomy. Fast Fourier transform (FFT) analysis of blood flow, the pulsatility index (PI) as a measure of ...

Although vascular bypass grafting remains the mainstay for revascularization for ischemic heart disease and peripheral vascular disease, many patients do not have healthy vessels suitable for harvest. Thus, prosthetic grafts made of synthetic polymers were developed, but their use is limited to high-flow/low-resistance conditions because of poor elasticity, low compliance, ...

OBJECTIVES: The purpose of this study was to evaluate which Doppler-derived flow index best predicts new distal left anterior descending coronary artery (LAD) stenosis in patients with left internal mammary artery (LIMA) graft. BACKGROUND: The LIMA flow measurement has been proposed to assess graft function, but it may be misleading ...

PURPOSE: Checking bowel viability is difficult but important during surgery for ischemic bowel disease or jejunal autotransplantation. We investigated the effectiveness of two-wavelength near-infrared spectroscopy (NIRS) to quantify tissue oxygen saturation (StO(2)), which can affect bowel viability during reconstruction of the cervical esophagus using a free jejunal graft. METHODS: Free ...

Cardiovascular magnetic resonance (CMR) with flow velocity mapping has emerged as a noninvasive method to measure flow in saphenous vein coronary artery bypass grafts. The aim of the current study was to retrospectively test two previously described analysis methods on a large CMR data set and to compare their diagnostic ...

BACKGROUND: Intraportal injection of donor antigens delays rejection of allografts (portal venous tolerance). The study aimed to investigate the possible influence of prior gadolinium chloride (Gd)-induced Kupffer cell blockade on tolerance to non-vascularized skin allografts induced by means of donor-specific intraportal blood transfusion. MATERIALS AND METHODS: Wistar rats (n = ...

BACKGROUND: Transthoracic Doppler echocardiography of internal mammary artery grafts (MAGs) has been tested by the supraclavicular approach, but little information is available about the parasternal approach. OBJECTIVE: To evaluate the usefulness of parasternal transthoracic Doppler echocardiography to assess the patency of left and right MAGs. PATIENTS AND METHODS: Forty-eight patients ...

OBJECTIVE: The radial artery is widely used as a bypass conduit in coronary artery bypass surgery, but the long-term flow readjustment in the hands and fingers induced by the removal of the radial artery is poorly understood. METHODS: Using pulse-volume-recording plethysmography, digital blood flow was measured semiquantitatively in 24 patients ...

Organ transplantation is associated with changes in graft blood flow, both acutely caused by reperfusion associated phenomena, and chronically due to e.g. denervation. The aim of the study was to investigate regional blood flow early after implantation of a syngeneic pancreas-duodenum transplant in rats, i.e. during reperfusion. Warm ischemia time ...

The composition of extracellular matrix during growth and regression of the neointima was analyzed during healing in a baboon aorto-iliac polytetrafluoroethylene graft. Graft neointimal thickening can be modulated by altering blood flow by construction of downstream arteriovenous fistulas. Normal flow with normal shear stress induces neointimal thickening, whereas high flow ...

Altered flow conditions are presumed to cause stenosis in vein grafts due to exaggerated neointimal formation. The aim of this study was to establish a mouse model of flow-regulated intimal hyperplasia (IH) in vein grafts. The caval vein was grafted into the common carotid artery of 38 mice, followed by ...

Spherical molecularly imprinted polymers (MIPs) specific to the beta-blocker propranolol have been synthesised using two different approaches and compared to traditional ground monolithic MIPs in HPLC and TFC applications. TFC is a LC technique used for rapid extraction of compounds directly from complex matrices. It can be easily coupled to ...

OBJECTIVE: The study was designed to assess the early changes in sternal perfusion after midline sternotomy and different (skeletonized versus semiskeletonized) techniques of internal thoracic artery (ITA) harvesting. METHODS: The experiments were performed in the swine model. After midline sternotomy, ITA harvesting (skeletonized technique) was performed unilaterally in Group I ...

The aim of this study was to determine the potential benefit of aerobic machine preservation (MP) with non-colloidal histidine-tryptophan-ketoglutarate (HTK) solution compared with MP with Belzer machine perfusion solution (MPS) and standard cold storage, after marginal kidneys had been obtained from non-heart-beating donors. Cardiac arrest was electrically induced in anaesthetized ...

The aim of this work was the application of computer and physical in vitro simulation methods for estimating surgery procedure hemodynamics. The modified Blalock-Taussig (mB-T) palliative surgical procedure is performed to increase the pulmonary blood flow in children with congenital heart defects. Such a systemic-to-pulmonary shunt yields substantial modification in ...

In this study, an analytical technique was developed to estimate the dynamic, three-dimensional wall shear and tensile forces within the arterial circulation and applied to our established model of flow-mediated graft remodeling within the rabbit carotid system. Through selective unilateral distal ligation, vein grafts were exposed to distinct flow environments, ...