This study assessed the postoperative microvascular hemodynamics in end-to-side arterial anastomoses of varied angles in order to determine whether the angle of the anastomosis affects arterial flow. Thirty male rats were divided into three groups of ten. Carotid to carotid end-to-side anastomoses were performed with anastomotic angles of 45, 90, ...

OBJECTIVES: The aim of the present study was to analyse the effects of various vasodilating stimuli on postoperative infrainguinal graft haemodynamics. DESIGN: Duplex derived haemodynamic parameters of infrainguinal bypass grafts were measured at rest and after postocclusion reactive hyperaemia, intraarterial papaverine (40 mgm) injection and peroral nifedipine (10 mg) administration. ...

The CA1 and hilar fields of the hippocampus are highly vulnerable to lack of oxygen after interruption of blood flow to the brain. Severe anterograde memory loss, seen in a significant proportion of heart attack survivors, has been attributed to selective bilateral ischaemic damage to the hippocampus. Animal models of ...

OBJECTIVES: To assess, in vivo, the loss of endothelial cells seeded in a Dacron graft at low, restricted arterial flow and at normal unrestricted flow. DESIGN AND SETTING: Laboratory animal study. MATERIALS: Indium-111-oxine labelled endothelial cells were seeded in externally supported, preclotted Dacron grafts, inserted as interposition grafts in the ...

PURPOSE: Experiments were designed to determine the effects of blood flow on endothelium-dependent relaxations in canine vein grafts. METHODS: Blood flow through reversed femoral vein grafts was either increased by a distal arteriovenous fistula (increased flow), unmanipulated (normal flow), or reduced by a proximal adjustable clamp (reduced flow). Six weeks ...

This study is concerned with an assessment of the quality of the blood vessels used in the construction of radiocephalic arteriovenous fistulae for haemodialysis vascular access in 20 patients. Following non-invasive preoperative assessment of the cephalic vein by means of a colour Doppler scanner, input impedance was determined intraoperatively from ...

Tubular polymeric materials modified by radiation techniques can be used as vascular prosthesis and components of prosthetic devices. The biological interaction between these materials and blood was studied by in vitro and ex vivo methods. Silicone rubber tubes were copolymerized with acrylamide and N-vinylpyrrolidone by radiation-grafting techniques. The irradiation was ...

A synthetic blood pool imaging agent labeled with 99mTc is reported. METHODS: The agent, methoxypolyethylene glycol-poly-L-lysyl-diethylenetriaminepentaacetate monoamide was synthesized from a covalent graft copolymer of methoxypolyethylene glycol succinate (molecular weight 5.1 kD) and poly-L-lysine (molecular weight average 35.6 kD) with subsequent modification of the product with diethylenetriamineacetyl residues. The polymer ...

Transcutaneous duplex ultrasound can be used to image and quantify blood flow in the proximal part of the internal thoracic artery to coronary artery bypass grafts. In addition to providing information about graft patency and blood flow for follow-up purposes, the technique also provides an opportunity to study the physiology ...

OBJECTIVE: To assess the power of operative flow measurements in the prediction of outcome after infrainguinal bypass operations for critical ischaemia DESIGN: Open study SETTING: University department of vascular surgery SUBJECTS: 197 patients operated on for critical ischaemia between 1 January 1982 and 31 December 1989 under the care of ...

Postoperative spasm of the internal mammary artery graft can cause morbidity and mortality after myocardial revascularization. To our knowledge, the ability of systemic vasodilators to overcome internal mammary artery spasm has not been studied clinically. In 50 patients in whom the left internal mammary artery was used for myocardial revascularization, ...

A new in vivo model has been developed for the quantitative study of promoters and potential promoters of angiogenesis. Full thickness rat skin autografts received a reproducible and uniform freeze injury, before being applied to full thickness wounds, in order to delay revascularisation. Blood flow in the grafts was measured ...

No controlled studies investigating the effect of specific cannulation techniques on AV graft survival time and/or patency rates appear in the literature. These techniques include but are not limited to the following: skin preparation, rotation of cannulation sites, antegrade versus retrograde cannulation, rotating the axis of the needle, rerotating axis ...

We investigated the clinical applicability of the transit-time ultrasound technique for quantitation of internal thoracic artery (ITA) graft flow in coronary artery bypass grafting. Intraoperative measurements of arterial and venous coronary graft flow were performed in 63 patients using an ultrasonic flowmeter. Native ITA blood flow was determined using a ...

To evaluate the accuracy of flow measurements in aortocoronary bypass grafts with the ultrasound transit-time method, an in vitro and in vivo comparison was carried out. The in vitro comparison with evaluation against both true flow and the ultrasound Doppler method, was carried out with a fresh saphenous vein mounted ...

To determine whether the blood supply to the hindlimbs of rats is altered by the tail-suspension model of weightlessness, rats were chronically instrumented for the measurement of femoral artery flow. Ultrasonic transit-time flow probes were implanted into 8-wk-old Wistar-Furth rats under ketamine-xylazine anesthesia, and, after 24 h of recovery, flow ...

To determine the effect of erythropoietin (EPO) on patency the haemodynamics and morphology in haemodialysis fistula/graft were prospectively assessed using ultrasonographic two-dimensional imaging and colour flow Doppler together with pulsed Doppler, prior to and during partial correction of anaemia with EPO. Nineteen radiocephalic fistula and 11 loop grafts in 30 ...

The effects of blood flow on the kinetics of smooth muscle cell (SMC) proliferation were examined in canine autogenous vein grafts with a distal poor run-off model. The in vivo bromodeoxyuridine (BrdU, a thymidine analogue) incorporation method was used to label proliferating SMCs in each layer of the vein graft. ...

Polytetrafluoroethylene (PTFE) grafts placed into the arterial circulation of baboons for 8 weeks under high blood flow (HF) conditions develop a thin intima composed of smooth muscle cells (SMCs) and extracellular matrix beneath an endothelial monolayer. When these grafts are returned abruptly to normal flow (NF), they develop marked intimal ...

Authors report their experiences with arterial revascularization of the heart using the internal mammary artery (IMA). A method of intraoperative measurement of the free cut end and the effective graft flow of the IMA after meticulous anatomical dissection is described. Free cut end IMA flow was measured both at systemic ...

Dentoalveolar blood from extraction sites immediately after surgery and venous blood from 28 adult patients was compared for quantitative, qualitative, chemical, and cellular differences. The absence of stem cells, osteoblasts, and osteoclasts from dentoalveolar blood suggests a very low osteogenic potential, no more than that of venous blood. This finding ...

This study investigated the controversial relationship between reduction in internal mammary artery (IMA) graft blood flow and left ventricular function in a canine model. Ten dogs underwent IMA grafting to the left anterior descending coronary artery. The left anterior descending coronary artery proximal to the IMA graft was intermittently occluded ...

Amino-terminal fragments of PTHrP were previously shown to increase regional blood flow in laboratory animals. Since PTHrP is produced in the lactating mammary gland and associated nutrient vessels, we examined the effects of peptide fragments of PTHrP on the hemodynamics of the mammary gland of dried sheep. The left arterial ...

When a primary anastomosis of the trachea is not feasible, grafting is required. We assessed the maximum length of tracheal autografts in 25 dogs. We used the autografts in this experimental study to avoid the immunologic complexity of allografts. Sections of cervical trachea ranging in length from 2.4 cm (6 ...

STUDY OBJECTIVE: To determine the effect of reperfusion of the grafted liver on transcranial Doppler blood flow velocity in the middle cerebral artery in humans during orthotopic liver transplantation. DESIGN: Clinical study. SETTING: University hospital. PATIENTS: 6 patients scheduled for orthotopic liver transplantation. INTERVENTIONS: Middle cerebral artery blood flow velocity ...

The uptake of platelets, fibrinogen and leucocytes in relation to blood flow was studied in ePTFE arterial grafts inserted in both common carotid arteries of 10 adult sheep. Autologous platelets labelled with In-111, autologous leucocytes labelled with Tc-99m and homologous fibrinogen labelled with I-125 were used. The leucocyte uptake was ...

A hydrodynamic model for the part of the human arterial network below the renal arteries has been constructed using specially fabricated distensible tubes and a pulsatile pump to simulate an aortoiliac bypass. The experiments and the computer model indicated that no 'steal' occurred due to the insertion of the bypass ...

To investigate the correlation between the long-term results of an extra-anatomic bypass and operative flow waveform analysis, we retrospectively reviewed 32 axillofemoral and 21 femorofemoral bypasses for between 1 and 5 years after surgical repair. For the grafts with a type O or I flow waveform pattern, the patency at ...

The effects of changes in shear stress (shear stress variation) on production of prostacyclin (PGI2) were examined in canine autologous vein grafts, which were implanted in the poor or normal distal runoff limbs. Four weeks after grafting, the vein grafts were perfused ex vivo and PGI2 was assayed as 6-ketoprostaglandin ...

A chronic arteriovenous (AV) blood access shunt has been developed in baboons. It is composed of silicone rubber tubing extensions bonded to vascular graft polytetrafluoroethylene (ePTFE) cuffs, for creating anastomoses with the distal aorta and inferior vena cava. Following surgical implantation, shunts remain patent for months (X = 9 +/- ...

To test the ability of duplex Doppler echocardiography from the supraclavicular fossa in detecting the left internal mammary artery (LIMA) graft flow and to verify the flow velocity measurement with this method, we studied 12 consecutive patients who underwent coronary artery bypass graft surgery with the LIMA graft. Duplex Doppler ...

In this article, a numerical simulation of steady flow across an end-to-end vascular bypass graft anastomosis is presented. In vitro experiments were performed to determine the variations in the conduit cross section at the anastomosis. Penrose surgical drainage tubing was used to simulate an artery and was anastomosed with Polytetrafluoroethylene ...

An end-to-end anastomosis was done in the center of a 5-cm devascularized jejunal segment in 5 control laboratory rabbits and 14 experimental rabbits. A second group consisted of 5 control animals and 11 experimental animals having end-to-end jejunojejunostomy in the center of a 10-cm devascularized jejunal segment. In the experimental ...

In the postoperative patient with anginal symptoms, differentiation between bypass graft compromise and nonischemic causes has until now been accomplished only by means of x-ray angiography. A non-invasive test is clearly desirable. The authors used a cine phase-contrast (PC) magnetic resonance (MR) imaging technique to characterize blood flow in native ...

An alternative graft is needed for coronary bypass operations in patients lacking suitable autologous vessels. We therefore studied Denaflex, a biologic graft, in a dog ex-vivo shunt model to determine whether heparin treatment makes this graft less thrombogenic. Comparison was also made to Bioflow, a nonheparinized biologic graft. Fibrinogen deposition ...

A laser Doppler tissue perfusion monitor was used to measure sternal blood flow before, during, and after mobilization of the internal thoracic arteries in 24 patients undergoing coronary artery bypass grafting. To minimize chest wall injury, a narrow pedicle was mobilized. Bilateral flow data were available from 15 of the ...

Biomaterials exposed to blood often fail due to thrombosis. Gas nuclei (air) in the material are thrombogenic and a potential cause of failure. The effects of gas nuclei on patency and blood flow were studied in 4 mm diameter arterial grafts (Gore ePTFE; Johnson and Johnson Vitagraft ePTFE; Bard ACG ...

Noninvasive telemetric monitoring of canine heterotopic cardiac allograft unipolar peak-to-peak amplitude (UPPA) has permitted prospective surveillance for rejection; moreover, this technique is able to reliably detect rejection before the development of histologic evidence of myocyte necrosis. This study was performed to determine whether early cardiac allograft rejection and the accompanying ...

In order to determine the absolute minimum tissue blood flow (TBF) for safe colonic anastomosis, the wound healing process of anastomotic sites with varying degrees of TBF, measured by laser Doppler velocimetry (LDV), was examined in dogs. Firstly, to clarify how well the LDV value reflects TBF, the correlation between ...

A prospective randomized placebo-controlled trial was conducted to determine the effects of the stable prostacyclin analogue iloprost on early graft patency and hemodynamic parameters during femorodistal reconstruction for critical leg ischemia. Peripheral resistance and graft blood flow were measured using an operative Doppler flowmeter and graft pressure transducer. Postoperative graft ...

In a group of 22 patients, Doppler signals from the proximal part of the internal mammary artery graft were studied from the supraclavicular fossa as well as from the high intercostal spaces. An adequate signal was found more often from the supraclavicular position. Both positions showed higher peak systolic than ...

The criteria by which revascularizations are measured ultimately is patency, since cessation of blood flow equates with a failed graft and usually signals a return to the preoperative limb perfusion or less. An uncommonly analyzed criterion for graft function is blood flow capacity through the reconstruction which is critically important ...

Spasm of the internal mammary artery (IMA) during coronary bypass grafting may cause inadequate graft flow and makes accurate placement of sutures difficult. In addition, IMAs with poor intraoperative flow rates are more likely to occlude. In this study three methods for spasm prevention were compared in 51 patients undergoing ...

A prospective study was performed that allowed a quantitative estimation of blood loss in excision and grafting of adult burn injuries. The average value for blood loss was 9.2 per cent of the patient's estimated blood volume or 387 ml per 1 per cent burn excised and grafted. There was ...

Preoperative external beam radiation therapy (RT) is an increasingly popular form of adjunct therapy for rectal cancer; however, little is known about its effects on healing of colorectal anastomoses. We serially evaluated colorectal anastomotic healing following moderate dose RT. Twenty-four adult female pigs were administered 4250 centiGrays (cGy) of external ...

Fluid dynamic properties of Dacron vascular grafts were studied under controlled steady-flow conditions over a Reynolds number range of 800 to 4500. Knitted and woven grafts having nominal diameters of 6 mm and 10 mm were studied. Thermal anemometry was used to measure centerline velocity at the downstream end of ...

Nine patients with end-to-side aortobifemoral bypasses were studied in the first year after surgery using color duplex imaging to determine the source of pelvic blood flow. No patient had clinical evidence of postoperative pelvic ischemia. Six of nine patients were found to have occluded distal aortas by duplex studies performed ...

We investigated chest wall blood flow in a canine model to determine if the technique used to harvest the mammary artery has a differential effect on residual chest wall blood flow. Eight dogs underwent bilateral internal mammary artery mobilization; one artery was harvested as a pedicle and the other was ...

To determine the safety of intersecting staple lines, 22 pigs were operated upon with a functional end-to-end enteroanastomosis 40 cm distal to the ligament of Treitz using linear stapling devices. The procedure was repeated on the colon, where a colocolostomy was created. The blood flow at intersecting staple lines and ...

There are scant experimental data directly comparing the healing of the circular-stapled (CS) anastomotic technique with the standard Czerny-Lembert two-layer hand-sewn (HS) anastomotic technique during the acute and chronic phases of healing. The purpose of this study, therefore, was to serially evaluate wound healing in CS and HS anastomoses in ...