In composite arterial coronary grafts (CACGs), transport phenomena and geometry may considerably alter blood flow dynamics. CACGs aim at revascularizing pathological arteries according to the human anatomy. However, the exact mechanisms causing the failure of coronary bypass grafting are not yet well elucidated. In the present study, computational fluid dynamics ...

BACKGROUND: Thirty-day testing of the MC3 Biolung (MC3 Inc, Ann Arbor, MI) total artificial lung (TAL) was performed to prepare for future clinical testing. METHODS: TAL inlet and outlet grafts were sewn to the pulmonary artery and left atrium of 8 sheep (35.6 +/- 1.6 kg), and the TAL was ...

Extracorporeal photochemotherapy (photopheresis, ECP) is a novel therapeutic method for patients who do not respond to immunosuppressive medications, and gaining interest in the treatment of Graft-vs-Host Disease. This paper is focused on the optical transmission properties of plastic bags which can be used in an independent (off-line) method of ECP, ...

Vascular grafts are in large demand for coronary and peripheral bypass surgeries. Although synthetic grafts have been developed, replacement of vessels with purely synthetic polymeric conduits often leads to the failure of such graft, especially in the grafts less than 6 mm in diameter or in the areas of low ...

A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by dialysis needle flow impingement within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. Preliminary in ...

Cardiovascular-related syndromes are the leading cause of morbidity and mortality worldwide. Arterial narrowing and blockage due to atherosclerosis cause reduced blood flow to the brain, heart and legs. Bypass surgery to improve blood flow to the heart and legs in these patients is performed in hundreds of thousands of patients ...

OBJECTIVE: We sought to evaluate if patients with proximal critical circumflex (CX) lesions did better with single SV-CABG on the best obtuse marginal (OM), or with sequential SV-CABG on two OM branches. DESIGN: Ninety patients were prospectively randomised to single SV-CABG on the best OM (sSV-CABG-45 patients; Group A) or ...

PURPOSE: To characterize the flow of a novel ureteral stent composed of a nickel-cobalt-chromium-molybde-num alloy and compare it with flow in a standard ureteral stent. MATERIALS AND METHODS: Six 6F Resonance stents and six 6F standard Black Beauty ureteral stents were placed in six Yucatan minipigs, with each pig serving ...

The supercharge technique has become widely prevalent in the field of esophageal reconstruction. Despite the logical advantages with this technique, the actual degree of its effect on the blood circulation is not clear. There may be cases in which the supercharge technique is not necessary for survival of the jejunum. ...

Breast asymmetry was believed to be related to the asymmetry of anterior chest wall blood supply and subsequently to etiology of idiopathic thoracic scoliosis in female adolescents. Recent investigations on the anterior chest wall blood supply with colour Doppler ultrasonography in such individuals did not show anatomic and hemodynamic abnormalities. ...

PURPOSE: The purpose of this study was to assess the effects of hemodynamic alterations on vein graft flow during peripheral vascular surgery. It was hypothesized that vasopressors can be administered without compromising flow through the vein grafts. SETTING: Tertiary care center, university medical center. Study DESIGN: Randomized placebo-controlled double-blinded study. ...

OBJECTIVE: Venous dilatation and wall thickening are part of the maturation of an arteriovenous fistula (AVF). However, the underlying mechanism of AVF remodeling remains unknown. We therefore studied whether matrix remodeling elicited by matrix metalloproteinases (MMPs) may contribute to AVF maturation. METHODS: A femoral AVF model in rats was established ...

Breast asymmetry was believed to be related to asymmetry of anterior chest wall blood supply and subsequently to aetiology of idiopathic thoracic scoliosis in female adolescents. Recent investigations on the anterior chest wall blood supply with Colour Doppler Ultrasonography (CDU) in such individuals did not show anatomical and hemodynamic abnormalities. ...

This paper presents some ideas for the membrane thickness design of of implantable bio-micro-electro-mechanical systems (bio-MEMS) for the in situ monitoring of blood flow. The objective is to develop a smart wireless sensing unit for non-invasive early stenosis detection in heart bypass grafts. The design includes considerations of nonlinear material ...

PURPOSE: The objective was to evaluate the impact of anastomosis diameter on blood flow in an arteriovenous fistula (AVF), comparing two different anastomosis sizes with a modified side-to-side technique in canine femoral arteries. METHODS: Ten mongrel dogs were subjected to two AVFs each, both using a modified side-to-side technique. On ...

The effectiveness of femoral bypass grafts is correlated with the geometric configuration and hemodynamics of the bypass and the arteries. As an attempt to develop a new design for femoral bypass grafts, we present a novel geometric configuration for a symmetrically implanted 2-way bypass graft. In order to investigate how ...

Continuous locked suture technique in arterial anastomosis was used in a rat heterotopic small bowel transplantation model. Blood loss, time consumption and success rate of the technique, as well as long-term blood flow and histological changes of arterial anastomosis and intestinal graft were compared with the traditional simple continuous suture ...

Neointimal hyperplasia is the most common complication of all forms of arterial reconstructions. This response of the vascular wall to injury is influenced by many factors, especially, but not limited to, by the hemodynamic profile in the area of vascular anastomosis and in its close proximity. To eliminate this negative ...

BACKGROUND: This study was conducted to investigate how brief pretreatments with 4 different vasodilators applied topically at normal body temperature affect blood flow in the internal mammary artery. METHODS: One hundred patients who had an internal mammary artery mobilized as a pedicle for coronary artery bypass grafting were randomly assigned ...

Restenosis after balloon angioplasty and stenting is exacerbated by low flow. Flow-dependent restenosis after angioplasty but not stenting is prevented by the antioxidant pyrrolidine dithiocarbamate (PDTC). c-jun may play a role in these events as AP-1 activity is both flow and redox sensitive. Carotid arteries of cholesterol fed rabbits underwent ...

Mechanical conditioning represents a potential means to enhance the biochemical and biomechanical properties of tissue engineered vascular grafts (TEVGs). A pulsatile flow bioreactor was developed to allow shear and pulsatile stimulation of TEVGs. Physiological 120 mmHg/80 mmHg peak-to-trough pressure waveforms can be produced at both fetal and adult heart rates. ...

Intimal hyperplasia develops preferentially in regions where the blood flow is stagnant and wall shear stress low. The small amplitude helical geometry of the SwirlGraft was designed to ensure physiological-type swirling flow, and thus suppress the triggers. We report the first conceptual testing of the SwirlGraft. Primary, assisted primary and ...

AIMS: The aim of this study is to evaluate the influence of dividing the inferior mesenteric artery (IMA) and preserving the left colic artery (LCA) on rectosigmoid cancer surgery. PATIENTS AND METHODS: Colonic blood flow at the proximal site of the anastomosis was measured by laser Doppler flowmetry in 96 ...

OBJECTIVE: Although many efforts have been made to generate small-diameter (< or =5mm) vascular grafts by means of tissue engineering, improvement in patency and functionality still remains a great challenge. It is our hypothesis that to achieve long-term functionality and patency, not only the complete lining with endothelial cells but ...

BACKGROUND: To determine whether a coronary artery bypass graft (CABG) is patent, we examined the flow of the left internal mammary artery (LIMA) to the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE). PATIENTS AND METHODS: Eighty-seven patients with CABG (LIMA to distal LAD) were enrolled in the ...

This paper presents the fluid dynamics of blood flow in a coronary bypass model of the aorto-right coronary bypass system. Three-dimensional computational fluid dynamic simulations are developed of the blood flow in coronary artery-bypass systems, using the computational fluid dynamics software (FLUENT 6.0.1). These blood flow simulations are performed within ...

OBJECTIVE: We sought to determine the added value of simultaneous imaging of intravenously infused microbubbles that are being used to dissolve an intravascular thrombus with therapeutic ultrasound (TUS). METHODS: In a chronic canine arteriovenous graft occluded by a thrombus, TUS (1 MHz) was applied through a 6-cm-thick tissue-mimicking phantom (measured ...

OBJECTIVE: The aim of this retrospective study was to evaluate the possibility to predict postoperative graft patency in coronary surgery by means of intraoperative transit-time flow measurement. METHODS: Of 3567 patients submitted to isolated myocardial revascularization from June 1997 through June 2003, 157 (4.4%) underwent both intraoperative transit-time flow measurement ...

The purpose of this study was to examine the feasibility of the combined use of intraluminal biodegradable shunts and surgical adhesives for sutureless distal coronary anastomosis. Eighteen LITA-LAD anastomoses were created in a porcine beating heart model. In group I (n=9) a custom-made silicone Y-shunt provided internal stability, while three ...

BACKGROUND: Observational studies suggest that skeletonization of the internal thoracic artery (ITA) can improve conduit flow and length and reduce deep sternal infections and postoperative pain. We performed a randomized, double-blind, within-patient comparison of skeletonized and nonskeletonized ITAs in patients undergoing coronary surgery. METHODS AND RESULTS: Patients (n = 48) ...

Transitional blood flow in an arteriovenous graft under various conditions of flow division was examined through direct numerical simulation. This junction consists of an inlet vessel (prosthetic graft) connected to a host vessel (vein) at an acute angle (21.6 degrees ). Inlet Reynolds numbers, based on mean velocity and graft ...

BACKGROUND: The sequential bypass technique is a routine method of myocardial revascularization. The aim of this study was to determine flow characteristics of individual and sequential bypass grafts created on the beating heart. METHODS: Between January 2003 and February 2004, a consecutive series of 50 patients underwent off-pump coronary bypass ...

BACKGROUND: Early coronary bypass graft failures may be preventable if identified intraoperatively. The purpose of this investigation was to compare the diagnostic accuracy of two intraoperative graft assessment techniques, transit-time ultrasound flow measurement and indocyanine green fluorescent-dye graft angiography. METHODS: Patents undergoing isolated coronary artery bypass grafting with no contraindications ...

BACKGROUND: Clinical practice guidelines recommend that the preferred method of surveillance for arteriovenous fistula (AVF) is the measurement of AVF blood flow (Qa). As these recommendations are based on observational studies, we conducted a randomized, prospective, double-blind, controlled trial to assess whether Qa surveillance results in an increased detection of ...

This paper presents a comparative study of simulated blood flow in different configurations of simplified composite arterial coronary grafts (CACGs). Even though the composite arterial grafting is increasingly used in cardiac surgery, it is still questionable whether or not the blood flow in such grafts can adequately meet the demands ...

OBJECTIVE: Milrinone has been known to dilate the internal thoracic artery (ITA) and the radial artery (RA). The effect of milrinone, however, on each graft is unclear when the left ITA (LITA) and the RA form a Y-graft. This study evaluated the changes in blood flow of a composite Y-graft ...

We present a case of intermittent cessation of blood flow through stent struts during systole, with normal flow during diastole in the previously stented ostial vein graft. After reviewing the initial procedure, we discovered that the operator had difficulty in positioning the stent. After stent deployment, the ostial stent was ...

BACKGROUND: The purpose of this study was to evaluate angiographic results of patients subjected to a technique variation of Vineberg's procedure, as well as their morbidity and mortality in immediate postoperative period, and to analyze the flow of grafted left internal thoracic artery (LITA) at rest and under stress. METHODS: ...

The purpose of the study was to determine simultaneously the temporal changes in luminal vessel area, blood flow, and wall shear stress (WSS) in both the anastomosed artery (AA) and vein (AV) of arteriovenous polytetrafluoroethylene (PTFE) grafts. PTFE grafts were placed from the iliac artery to the ipsilateral iliac vein ...

A thorough knowledge of both vascular anatomy and hemodynamics is of high interest for the understanding of the severity of the underlying disease, the therapeutic decision-making and follow-up. In this context, flow-sensitive 3D magnetic resonance imaging (MRI) offers the possibility to simultaneously acquire detailed information about vascular hemodynamics and morphology. ...

INTRODUCTION: Reperfusion injury occurs after ischemic storage of the liver. The release of free radicals from endothelial cells leads to increased adherence of polymorphonuclear neutrophils to endothelium and further release of proteases and free radicals that alter the microcirculation and produce graft dysfunction. Acute blood leukocyte reduction after reperfusion may ...

The main purpose of the study was to verify if helical flow, widely observed in several vessels, might be a signature of the blood dynamics of vein graft anastomosis. We investigated the existence of a relationship between helical flow structures and vascular wall indexes of atherogenesis in aortocoronary bypass models ...

In this paper, we investigate the behavior of the pulsatile blood flow in a stenosed right coronary artery with a bypass graft. The human blood is assumed to be a non-Newtonian fluid and its viscous behavior is described by the Carreau model. The transient phenomena of blood flow though the ...

In pancreas transplantation (PTx), ischemia/reperfusion-induced deterioration of graft-microcirculation is accompanied by alterations of intermittent capillary perfusion (IP; alternating cessation and resumption of capillary blood flow) is known to counteract malperfusion. Incidence and effectiveness of IP following short- versus long-term preservation of pancreas grafts with University of Wisconsin (UW) solution has ...

OBJECTIVE: To investigate the value of intraoperative blood flow measurements on early and long-term patency of above-knee prosthetic femoropopliteal bypass. METHODS: Flow was measured with a transit time flowmeter before (basal flow) and after an intragraft injection of papaverine (papaverine flow) in 87 operations (86 patients) between January 1990 and ...

Recent guidelines have recommended performing native arteriovenous fistulae (AVF) in hemodialysis patients rather than synthetic grafts whenever possible. However, early failure of AVF may reach up to 50%. The purpose of this study was to assess the factors associated with early failure of such procedures in hemodialysis patients. A prospective ...

Coronary artery bypass graft (CABG) is a routine surgical treatment for ischemic and infarcted myocardium. A large number of CABG fail postoperatively because of intimal hyperplasia within months or years. The cause of this failure is thought to be partly related to the flow patterns and shear stresses acting on ...

A common procedure for hyperfunctioning arteriovenous fistulas is banding, baring the potential for complications such as pre- and poststenotic dilatations and recurrence of high flow caused by slipping of the band itself. We describe a new technique that ensures proper fixation of the graft to prevent anastomotic aneurysms and enlarge ...

PURPOSE: The effectiveness of angioplasty can be assessed by access blood flow (ABF) measurements after the procedure; however, ABF after angioplasty is highly variable. The purpose of this study was to determine if the level of ABF achieved after angioplasty of arteriovenous (AV) grafts was predictive of subsequent graft outcomes. ...

PURPOSE: The objective of this study was to assess the blood flow in arteriovenous (AV) communications comparing autologous and homologous veins, in the femoral vessels of dogs. METHODS: Ten mongrel dogs were used for the blood flow analysis, and two AV grafts (AVG) were placed in each of them. The ...