The assessment of small bowel graft viability by means of energy metabolism and tissue blood flow was investigated and compared with pathological findings. Syngeneic heterotopic small bowel transplantations were performed using male Lewis rats, which were divided into four groups according to the duration of cold preservation in University of ...

Employing a validated finite volume code, a computer-aided design of the distal end of a femoral graft-artery junction has been considered to simulate transient three-dimensional blood flow for various flow input waveforms. The study relies on the hypothesis that large sustained wall shear stress gradients play a major role in ...

No-flow has been reported after 10-15% of percutaneous interventions on degenerated saphenous vein grafts. In this prospective study of 36 degenerated saphenous vein graft lesions (32 patients), no-flow (TIMI flow < 3 in the absence of a significant lesion or dissection) occurred in 15/36 (42%) lesions. A total of 32 ...

PURPOSE: Graft procoagulant activity is determined by thrombin (IIa) and activated factor X (Xa) that binds to thrombus. Thrombus-associated factor Xa and thrombin are resistant to antithrombin III-dependent therapy (heparin). To avoid complications and costs associated with systemic administration, we evaluated whether locally applied antithrombotic agents inhibit prosthetic graft procoagulant ...

Implanted vascular grafts often fail because of the development of intimal hyperplasia in the anastomotic region, and compliance mismatch between the host artery and graft exacerbates the problem. This study focused on the effects of radial artery wall motion and phase angle between pressure and flow waves (impedance phase angle ...

Sirolimus (rapamycin) has a macrolide structure and is under clinical investigation as an immunosuppressant after organ transplantation. An HPLC/mass spectrometry assay to quantify sirolimus in blood was developed. 28-O-Acetyl sirolimus was used as internal standard. Blood samples were extracted with C18 columns. The extracts were injected into an HPLC system ...

An accurate model of the pressure-flow relationship of a stenosis is necessary for the correct interpretation of haemodynamic measurements. Modelled femoral artery stenoses were tested in vitro and the pressure drop: flow ratio (resistance) was most accurately represented by a fixed component (Rf) combined with a variable component (Rv) that ...

OBJECTIVES: To validate the new CardioMed CM 4000 transit time ultrasound apparatus for intraoperative measurement of volume blood flow in vivo in man. DESIGN: Open, prospective series. MATERIALS: Thirteen patients undergoing in situ saphenous vein grafting for chronic critical leg ischaemia and 12 patients subjected to myocardial revascularisation with the ...

The motion of guanine particles was recorded by video to visualize transitional flow phenomena in models of a proximal side-to-end anastomosis. Close examination of successive video fields revealed that above a critical Reynolds number, particles were periodically shed into the graft from a vortex situated near the anastomosis heel, and ...

BACKGROUND: The purpose of this work was to study, in a theoretical electric model the effect that an adjunctive arterio-venous fistula (AVF) produces on the flow patterns of a distal infrapopliteal bypass. METHOD: A theoretical electric model that mimics a femoro-infrapopliteal bypass with an adjunctive AVF was designed. Based on ...

Abrupt reductions in fluid shear stress induce subendothelial smooth muscle cells (SMCs) to proliferate in experimental prosthetic grafts. Platelet-derived growth factor (PDGF), an important SMC mitogen, is expressed by cultured endothelial cells and modulated by shear stress. We hypothesized that this growth factor would be modulated by changes in shear ...

We have previously shown that the trisaccharide raffinose is largely responsible for the superior lung graft performance seen after storage in University of Wisconsin solution. To investigate the use of osmotic agents in perfusates for hypothermic lung graft storage, we compared saccharides of various molecular weights in an isolated rat ...

The features of intimal hyperplasia at the distal end-to-side anastomosis of arterially implanted autovein bypass grafts in dogs were examined using light and transmission electron microscopy. The bypass grafting was done under conditions of reduced blood flow with an abnormal flow wave and high peripheral resistance. Anastomotic intimal hyperplasia was ...

BACKGROUND: Vasoactive agents are frequently needed in patients undergoing myocardial revascularization. The purpose of this study was to examine blood flow in the internal mammary artery (IMA) during infusion of drugs that are commonly used after myocardial revascularization. METHODS: A canine right heart bypass preparation allowed precise control of cardiac ...

After a burn injury, the hemodynamics of a patient is changed. There is usually a fall in hematocrit. In addition to this, there is the loss of blood during the grafting procedure. Some patients cannot tolerate this loss of blood. The method we use to help decrease the loss of ...

OBJECTIVE: Although the role of blood flow has been investigated in animal models of intimal hyperplasia, there have been no detailed studies in intact human vein owing to the difficulties in designing a suitable laboratory model. The aim of this study was to develop a flow model of human vein ...

Islet-like cell clusters (ICCs) were prepared from the fetal porcine pancreas by a culture technique. The ICCs (approximately 500) were implanted under the left renal capsule of nude (nu/nu) C57BL/6J mice. Six weeks, months, 12 months, or 16-24 months later, the animals were anesthetized and the blood flows to the ...

Lower rates of anastomotic leakage have been reported after rectal resection with a colonic pouch-anal anastomosis than with a conventional straight anastomosis. The microcirculation in the bowel segment that was used for construction of a colonic pouch or a conventional straight anastomosis was examined. Transmural colonic blood flow was measured ...

BACKGROUND: The skeletonization technique of the internal thoracic artery (ITA) is used as a dissection technique for myocardial revascularization procedures. This study compared free flow between skeletonized ITA grafts and ITA pedicled grafts. METHODS: The ITA pedicled grafts were sprayed and wrapped in sponges soaked in dilute papaverine solution in ...

PURPOSE: Our purpose was to investigate the hemodynamic theory that the blood flow rate through a stenotic arterial graft is limited by the onset of turbulence, which acts as a barrier at peak systole against further increases in systolic flow. METHODS: We used duplex ultrasonography to examine 25 stenotic infrainguinal ...

BACKGROUND: Noninvasive quantitative assessment of internal thoracic artery (ITA) graft function at rest and during exercise is important in patients who have undergone coronary artery bypass grafting. METHODS: Blood flow in the ITA graft was measured using transthoracic color Doppler echography before and after operation in 50 patients who underwent ...

OBJECTIVES: Determination of the true coronary artery bypass graft function requires quantification of the flow rate within the graft. The purpose of the present study was to assess the feasibility of characterizing and quantifying graft flow by magnetic resonance phase velocity mapping. MATERIALS AND METHODS: Twenty-seven patients with 41 angiographically ...

OBJECTIVE: The low perioperative flow rates of internal thoracic artery (ITA) conduits have been regarded as a limitation of their use in critical coronary situations with a high myocardial blood demand. To clarify whether these restrictions are justified, early postoperative flow rates were determined. METHODS: Following bilateral ITA grafting, 48 ...

PURPOSE: To test the reliability and performance of two physical diagnosis algorithms for use in physical examination of vascular access grafts. MATERIALS AND METHODS: Grafts were assessed in 39 patients by means of physical examination performed by four observers. Grafts were characterized as having a thrill, pulse, or indeterminate examination ...

The effect of the geometry of the vessel and the number of anastomoses on the blood flow was studied. Four different shapes of the vessel were constructed by using a 6-cm-long double vein graft model with three anastomoses: (1) an alpha loop, (2) an omega loop, (3) a sigmoid curve, ...

Vascular grafts are widely employed in clinical practice and still pose significant problems of compatibility and longevity, particularly when the prosthesis is to replace arteries of small diameter. Once a graft has been implanted in the vascular tree, there is no easy way of assessing its interactions with the surrounding ...

To study the effect of cardioprotection type on haemolysis, 100 patients scheduled for elective coronary artery bypass grafting were allocated to receive either blood cardioplegia (BCP) or crystalloid cardioplegia (CCP). Haemoglobin concentrations in plasma and urine were measured after induction of anaesthesia, 1 hour postoperatively and the next morning; blood ...

OBJECTS: Myocardial revascularization is performed preferentially with internal mammary artery grafts. Pedicle preparation and pharmacologic vasodilatory treatment vary greatly. Objective measurements are difficult since peripheral and later coronary vascular resistance and possible competitive flow of the native bypassed coronary artery will influence the results significantly. Our objectives were: (1) measurement ...

Microvascular perfusion of the anoderm was assessed by laser Doppler flowmetry in 27 patients with anal fissure. Anal pressure was recorded simultaneously. Both measurements were repeated 6 weeks after lateral internal sphincterotomy and compared with those obtained from 27 controls. Means(s.d.) maximum anal resting pressure was significantly higher in those ...

BACKGROUND: Cardiac catheterization is the only practical method of assessing internal mammary artery graft patency. A noninvasive method would be useful in patients with recurrence of anginal symptoms after coronary artery bypass graft surgery. We hypothesized that transthoracic echocardiography could provide information on blood velocity and anatomy and therefore has ...

PURPOSE: To produce biodurable small diameter microporous vascular grafts with self-sealing properties for vascular access, for peripheral vascular and potentially for coronary artery bypass. The prosthesis should retain compliance and pulsatile flow in situ using a unique modus operandi permitting wall compression which accommodates changes in volume. METHOD: We have ...

A new technique for visualizing the steady flow of a new type of test fluid is presented that produces quality photographic results at Reynolds numbers typically found in arterial bypass grafts. Room air functions as the test fluid and smoke from burning incense sticks provides the tracer particles. As an ...

BACKGROUND: A delayed revascularisation model has been used to assess the angiogenic activity of hyaluronan fragments on impaired wound healing. EXPERIMENTAL DESIGN: Revascularisation of single, full thickness skin autografts in rats was delayed by subjecting isolated grafts to a sublethal cryoinjury (freeze injury) before implantation. Hyaluronan fragments were delivered to ...

Transfusion-associated graft-versus-host disease (TAGVHD) occurs in immunocompromised persons who receive nonirradiated blood products containing immunologically competent donor lymphocytes. TAGVHD occurs almost exclusively as an acute illness and has a very high mortality rate. We describe a patient with a long history of non-Hodgkin's lymphoma in whom acute TAGVHD developed after ...

Agents that downregulate the induction of monocyte/macrophage tissue factor (TF) activity may attenuate the thrombotic risk associated with mechanical restoration of vessel patency or artificial arterial grafting. In such events, procoagulant macrophages in the atherosclerotic plaque and procoagulant monocytes adherent to artificial materials may be exposed to the blood stream. ...

Intraoperative changes in portal venous and hepatic arterial flow were compared in porcine recipients of reduced liver grafts with recipients of intact grafts and sham-operated controls. Control animals showed no significant changes in hepatic blood flow (measured with perivascular ultrasonic cuffs), heart rate, mean arterial pressure, cardiac output, acid/base balance, ...

An additional saphenous vein graft (SVG) sometimes is required to the same coronary system if acute internal thoracic artery (ITA) graft flow is inadequate. These experiments were conducted to determine the consequences produced by ITA-SVG dual grafting. Fourteen dogs each received two coronary grafts (without bypass, using local occlusion) to ...

1. The aim of the present study was to investigate the effects of exercise and of sublingual glyceryl trinitrate on the pattern of blood flow, as studied by Doppler ultrasound, in internal mammary artery grafts performed to relieve severe stenosis of the left anterior descending coronary artery. The accessibility of ...

Flow structures were visualized in transparent polyurethane models of proximal side-to-end vascular anastomoses, using planar illumination of suspended tracer particles. Both the effects of geometry and flow division were determined under steady and pulsatile flow conditions, for anastomosis angles of 15, 30, and 45 degrees. The flow patterns were highly ...

The dynamic reactivity and the acute, recruitable flow capacity of an internal thoracic artery (ITA) graft remains unclear. These experiments were conducted in 20 anesthetized dogs with the left ITA grafted to the circumflex artery, off pump, using a brief local occlusion. The left main coronary artery was occluded, rendering ...

OBJECTIVES: To evaluate the effect of low molecular weight heparin (LMWH), dextran 70 and their combination on platelet adhesion and fibrinogen uptake in ePTFE grafts in an experimental sheep model. DESIGN: Prospective open study. SETTING: Animal Laboratory of a University Hospital. MATERIALS: Early thrombogenicity of ePTFE grafts was studied after ...

Self-assembled monolayers of alkylsiloxanes supported on polydimethyl siloxane (PDMS) rubber were used as model systems to study the relation between blood compatibility and surface chemistry. The inner lumen of PDMS tubes was first treated with an oxygen plasma. The resultant oxidized surfaces were postderivatized by reacting them with alkyltrichlorosilanes to ...

PURPOSE: The purpose of this article was to study the influence of the anastomosis angle on the flow fields at end-to-side anastomoses in vivo. METHODS: Polyurethane grafts of similar internal diameter to that of the abdominal aorta (8 mm) were implanted from the suprarenal to the infrarenal level in 10 ...

OBJECTIVES: To develop an in-vivo model to study the anastomotic flow patterns. DESIGN: Prospective, open, animal study. METHODS: Polyurethane grafts with an internal diameter equal to the abdominal aorta (8 mm) of 90 kg pigs were implanted as bypass grafts from the supra-renal to the infra-renal level. A novel technique ...

The internal mammary artery (IMA) is the conduit of choice for grafting the left anterior descending artery. However, arterial spasm and reduced early flow has been a cause of postoperative morbidity. The purpose of this study is to evaluate the effect of vasodilators on IMA flow. Fifty patients who had ...

The internal mammary artery is the preferred conduit for coronary artery bypass grafts. The effect on flow through the artery of both rotation and position of the artery pedicle was tested in an in-vitro setting on 20 arteries using a perfusate closely approximately the normothermic viscosity of blood. It was ...

PURPOSE: The influence of both blood flow and anastomotic technique on the development of anastomotic stricture formation was studied using a dog model. METHODS: Fifty-three dogs underwent distal colocolonic anastomosis with either an EEA (U.S. Surgical Corp., Norwalk, CT) circular stapler or a Czerny-Lembert two-layered, handsewn anastomosis. Blood flow was ...

Angiodynography has been recommended as a safe and accurate way to determine the blood flow through hemodialysis vascular grafts. This information might be used prophylactically to avert total graft occlusion. We examined the blood flows obtained by this technique after an interval of 6 months in a group of hemodialysis ...

The effects of isovolemic hemodilution with dextran-70 and albumin on thrombus formation in artificial arterial grafts were investigated. A polytetrafluoroethylene graft (PTFE, length 13 mm, inner diameter 3 mm) was inserted into the abdominal aorta of rabbits. Three groups of animals were studied; 1) animals receiving isovolemic hemodilution with dextran-70 ...

OBJECTIVE: To determine the extent to which epidural anaesthesia influences peripheral resistance and graft blood flow following femorocrural reconstruction. DESIGN: Prospective, controlled study measuring blood flow, arterial pressure and peripheral resistance in femorocrural bypass grafts for 20 min following onset of epidural anaesthesia with 15ml of 0.25% bupivacaine. PATIENTS: Twenty ...