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At least 1,387 records · Page 77Linked to original sources
PubMed2001

Vasoactive effects of 8-epi-prostaglandin F(2alpha)in isolated human placental conduit and resistance blood vessels in vitro.

The effects of 8-epi-prostaglandin F(2alpha)(8-epi-PGF(2alpha)) and the thromboxane A(2)-mimetic U46619 were examined on isolated human fetal placental arteries obtained from normal pregnancies and from those complicated by pre-eclampsia. The effects of these agents were examined on both conduit and resistance arteries. 8-epi-PGF(2alpha)was found to be markedly less potent than U46619 in constricting both size vessels. Vasoconstrictor EC(50)s for 8-epi PGF(2alpha)were 4.10x10(-7) m (2.02-8.35x10(-7) m) (mean, 95 per cent CI and 2.05x10(-6) m (0.43-9.89 x10(-6) m) in conduit and resistance arteries, respectively. The maximum vasoconstriction produced by 8-epi-PGF(2alpha)(112+/-17 per cent), (relative to maximum KCl induced vasoconstriction) in conduit vessels was significantly less than that caused by U46619 (152+/-20 per cent). In resistance vessels the maximum vasoconstrictor effects to 8-epi-PGF(2alpha)(208+/-10 per cent) and U46619 (201+/-19 per cent) were similar, and in both cases significantly greater than the maximal effects seen in conduit vessels. U46619 displayed a similar vasoconstrictor potency in both conduit (EC(50)=1.21x10(-9) m, 0.58-2.51x10(-9) m) and resistance arteries [EC(50)=5.95x10(-9) m, (0.81-43.60x10(-9) m] as was found for 8-epi PGF(2alpha). 8-epi-PGF(2alpha)was equipotent in resistance arteries obtained from women with severely pre-eclamptic pregnancies (EC(50)=1.25x10(-6) m, 0.25-6.17x10(-6) m) compared with normotensive controls. However, the maximum vasoconstrictor effect induced by 8-epi-PGF(2alpha)in placental resistance arteries was significantly reduced (99+/-20 per cent) in vessels obtained from severely pre-eclamptic compared with normal pregnancies. These results indicate that 8-epi-PGF(2alpha)displays differential vasoconstrictor activity in the fetal-placental vasculature. Furthermore the vasoconstrictor effects of 8-epi-PGF(2alpha)are reduced in pre-eclampsia, the effect being selective to placental resistance vessels. This reduction may occur as a result of more serious disturbances in the placental microcirculation with the disease process in pre-eclampsia.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1975

[The scope and limitations in the demonstration of vessels by angiotomography; their relationship with contrast and size and between detail and direction of cut (author's transl)].

Experiments with models and post mortem angiograms have shown that the supposed advantages of angiotomography, such as determination of the depth of vessels, cannot be achieved with accuracy if there is repeated change in direction of the vessels. Blurring of superimposed vessels depends not only on their contrast and calibre, but also on their alignment in relationship to the direction of blurring. Vessels running in the direction of blurring produce undesirable shadows through a considerable depth, whereas vessels running across the direction of blurring are rapidly blurred if not in the selected plane. The demonstration of vessels running at right angles to the direction of blurring may at times be very difficult with simultaneous tomography. The clinical significance of this finding is pointed out.

Angiography↗
PubMed2002

Breast reconstruction with the free bipedicled inferior TRAM flap by anastomosis to the proximal and distal ends of the internal mammary vessels.

Breast reconstruction after traditional radical mastectomy is particularly challenging for the plastic surgeon. Not only the breast, but subclavian and anterior axillary-fold deformities need to be corrected. An entire TRAM flap (including zone IV) is required, and bipedicled deep inferior epigastric vessels are needed to insure that the entire flap will survive completely. However, on the chest, it is difficult to locate the two suitable sets of recipient vessels for the two pedicles. The thoracodorsal vessels have usually been damaged during axillary dissection or radiation therapy. In the past, the proximal ends of the internal mammary artery and vein (IMA, IMV) have been used as recipient vessels with free flaps, with ligation of the distal ends. These authors have used both the proximal and distal ends of the IMA and IMV as recipient vessels for end-to-end anastomoses to the bipedicled deep inferior epigastric vessels (DIEA, DIEV) in seven clinical cases, with very satisfactory results obtained. Anatomic studies of the IMA and IMV were done in 10 dogs and two active patients, including studying hemodynamic changes at the proximal and distal ends of the IMA, and evaluation of perfusion units in the free bilateral TRAM flap. In the animal experiments, the mean pressure at the distal ends was 86/77 mmHg (left sides) and 87/78 mmHg (right sides); pressure was 63 to 71 percent of the proximal ends (p<0.05). There was no statistically significant difference between the pressures on the left and right sides. In the two patients, and in 5 others, the pressure at the distal ends was 66 and 58 mmHg, which was 75 to 77% of the pressure at the proximal ends. The blood flow at the two anastomotic stomas was similar in a 5-year follow-up. The clinical and experimental studies showed that the distal IMA has reduced perfusion pressure, but that it provides excellent flow and flap perfusion, allowing reliable use of two pedicles for survival of the entire flap.

Adult↗
PubMed2005

[Telemedical-supported screening of retinal vessels ("talking eyes")].

BACKGROUND: Cerebral and retinal vessels behave similarly under the influence of vascular risk factors. Several groups have shown that retinal microvascular abnormalities represent an independent risk factor with regard to strokes and heart attacks. AIM OF THE STUDY: The aim of this study was to perform a prospective screening examination with regard to retinal microvascular abnormalities as well as an extended vessel diagnosis in a subgroup of patients with lower arteriovenous risk values. METHODS: In the course of a prospective cross-sectional study ("Talking Eyes") between 1.9.2001 and 1.8.2002 a telemedical-supported screening of the retina (study I) was carried out in 7,163 subjects. The patients were selected without any inclusion or exclusion criteria. The mean age was 48.2 +/- 8 years (18 - 83 years) with a sex distribution of 39.2 % females to 60.8 % males. Digital fundus photos of the right and left eyes were taken for all patients. The pictures were taken without pupil dilation using a CANON-NM camera. The pictures and case histories were stored in a central server using web-based software (MedStage, Siemens). In a central reading centre, the arteriovenous ratio of both eyes was determined telemedically using the Parr-Hubbard formula and the retinas subjected to a standardised examination by an ophthalmologist. The retinal risk factor was calculated on the basis of the arteriovenous ration, the presence of microvascular abnormalities and the case history. The reproducibility of measurement of the arteriovenous ratio (Kronbach alpha coefficient) was evaluated by double measurements on 1,332 images. In a subgroup of study I with arteriovenous ratio values < 0.76 (N = 107), an extended vessel diagnosis with measurement of 24-h blood pressure and vessel-relevant blood values (homocysteine, cholesterol, LDL, HDL, CRP, TG, HbA1c) was carried out (study II). RESULTS: Study I: The Kronbach alpha coefficient as a measure of reproducibility amounted to 0.77. The mean arteriovenous ratio of the retinal vessels was 0.83 +/- 0.09 and showed a pronounced age dependence (R = 0.9, p < 0.0001). On multivariate testing the arteriovenous ratio correlated significantly (R = 0.33, p < 0.001) with the factors age, systolic blood pressure, diastolic blood pressure and body mass index. Diastolic blood pressure followed by age had the largest influence. The prevalence of microvascular abnormalities in the right (RE) and left (LE) eyes, respectively were: cotton wool foci RE 0.0015 %, LE 0.003 %, retinal haemorrhage RE 0.1 %, LE 0.1 %, focal stenoses RE 3.4 %, LE 3.4 %, tortuositas vasorum RE 4.1 %, LE 4.0 %, arteriovenous crossing signs RE 11.2 %, LE 11.2 %. On multivariate testing the occurrence of microvascular abnormalities correlated significantly (R = 0.38, p < 0.001) with the factors high blood pressure known from case history, body mass index, and gender. Arterial hypertension had the strongest influence followed by diastolic blood pressure. The calculated retinal risk factor correlated with the prevalence of angina pectoris. Study II: 2/3 of the subjects with arteriovenous risk factor values < 0.76 exhibited pathologically high 24-h blood pressure values. For these patients there were significant correlations between the arteriovenous ratio and the low-density lipoprotein concentration as well as the Framingham risk score. CONCLUSION: In the course of a prospective, telemedical-supported screening examination of the retinal vessels of more than 7,000 subjects the arteriovenous ratio exhibited a strong dependence on age and blood pressure. Among the subjects with lowered arteriovenous ratio values, 2/3 exhibited arterial hypertension in the 24-h blood pressure determination.

Adolescent↗
PubMed2006

Astragaloside IV dilates aortic vessels from normal and spontaneously hypertensive rats through endothelium-dependent and endothelium-independent ways.

The major active constituent of Astragalus membranaceus, astragaloside IV, has been found to have properties of increasing coronary flow and cardioprotection. In this study, we examined the direct effects of astragaloside IV on vessel dilatation and contraction in isolated aortic rings from both normal and stroke-prone spontaneously hypertensive rats (SHR-SP) in vitro. The results demonstrated that astragaloside IV could antagonize vessel contractions induced by phenylephrine and potassium chloride in a concentration-dependent way. Astragaloside IV reduced CaCl2-induced contractions in Ca2+-free solution. Astragaloside IV also dilated aortic vessels in a dose-dependent manner, which was partially endothelium-dependent through the nitric oxide (NO) and cGMP pathways. The aorta from 6-month-old SHR-SP rats showed impaired endothelium function, and astragaloside IV dilated the vessels from the hypertensive rats to a lesser extent as compared with normal control rats. In the presence of perivascular fat tissue, the contractile responses induced by angiotensin II and phenylephrine were also attenuated by astragaloside IV. Collectively, this study provides functional evidence that astragaloside IV exerts vessel dilatation properties through the endothelium-dependent NO-cGMP pathway in normal and hypertensive rats. It blocks extracellular calcium influx and participates in vessel relaxation partly through phenylephrine and angiotensin II inhibition when perivascular fat is present.

Animals↗
PubMed1999

Perioperative dilation for vessel-size discrepancy using a percutaneous transluminal angioplasty catheter.

The problem of vessel-size discrepancy is still unsolved in microvascular-free tissue transfers. In an effort to develop a technique perioperatively to dilate smaller vessel diameters, the authors utilized a catheter customarily used in coronary angioplasties, the percutaneous transluminal coronary angioplasty (PTCA) catheter. Twenty New Zealand rabbits were divided into two groups: Group 1 consisted of 14 experimental animals; Group 2 of six control animals. In both groups, a segmental defect of 2 cm was created in the proximal portion of the femoral artery just below the inguinal ligament, where the vessel diameter is 2.0+/-0.1 mm. In Group 1 animals, an arterial graft was harvested from the superficial femoral artery in the contralateral lower extremity, where the vessel diameter is 1.0+/-0.1 mm. The arterial graft along its entire length was dilated, using a PTCA catheter up to 2 mm in diameter. The duration of dilation was 3 min with pressure applied at 2.5 atm. Before and following dilation, sections were obtained from both ends of the graft for histologic comparison. The grafts were then interposed within the defect and microvascular anastomoses were performed. In the control group, an arterial graft of the same length as in the experimental group was harvested from the contralateral upper femoral region, where the vessel diameter is 2.0+/-0.1 mm. These grafts were then interposed within the defect and microsurgically anastomosed. Seven days later, the patency of the anastomoses was evaluated in both groups. In 13 of 14 rabbits in the experimental group, the anastomoses were patent and the arterial grafts maintained their dilated diameters (2 mm). In all six control animals, the anastomoses were patent. A statistical comparison of vessel patency using Fischer's exact chi-square test showed no significant differences between the experimental and control groups (p = 0.7). Histologically, the dilated arteries demonstrated intact endothelial layers.

Anastomosis, Surgical↗
PubMed1992

Magnetic resonance imaging of angiographically occult runoff vessels in peripheral arterial occlusive disease.

BACKGROUND: Bypass grafting to arteries of the lower leg has become standard surgical management of advanced peripheral vascular disease. Its success depends on identifying suitable distal vessels. Preoperative preparation includes imaging of the arteries of the lower leg, usually by conventional contrast arteriography. An alternative procedure, magnetic resonance (MR) angiography, has been successfully employed in patients with various cardiovascular diseases, but its possible value in patients with peripheral vascular disease has received little attention. METHODS: We used both conventional and MR angiography in preoperative studies of the lower-leg vessels of 23 patients (25 legs) with peripheral arteriosclerosis and arterial insufficiency, and developed independent therapeutic plans based on the information provided by each technique. When the plans differed, the interventional procedure judged more likely to save the limb was performed. The findings of conventional and MR angiography were verified by intraoperative arteriography, postinterventional arteriography, or direct operative exploration. RESULTS: MR angiography detected all vessels identified by conventional angiography, whereas conventional arteriography failed to detect 22 percent of the runoff vessels identified by MR angiography. The detection by MR angiography of vessels not identified by conventional angiography altered the surgical management of the disorders of four patients (17 percent) and guided successful bypass procedures. CONCLUSIONS: MR angiography is a noninvasive technique with greater sensitivity than conventional contrast arteriography for detecting distal runoff vessels in patients with peripheral arterial occlusive disease.

Aged↗
PubMed2001

Functional outcome of new blood vessel growth into ischemic skeletal muscle.

PURPOSE: The administration of angiogenic growth factors and the transfer of well-vascularized tissues have been shown to induce development of new blood vessels in ischemic muscle. The functional significance of these new vessels is unknown. The hypothesis of this study is that the transfer of vascularized muscle and the local infusion of basic fibroblast growth factor (bFGF) synergistically improve contractile function of ischemic skeletal muscle. METHODS: Twenty-six rabbits were divided into four groups. An ischemic hindlimb was created in each by ligating the right common iliac artery. The flap + bFGF group (n = 6) had transposition of a contralateral rectus muscle flap onto the thigh. Additionally, bFGF (3 ng/h) was continuously infused at the flap-thigh interface. In the flap group (n = 6), a similar muscle flap was created, but carrier solution was infused at the interface. In the bFGF group (n = 6), no muscle flap was created; instead, bFGF (3 ng/h) was infused into the external iliac artery of the ischemic limb. In the control group (n = 8), carrier solution was infused into the external iliac artery (no flap, no bFGF). After 1 week, the soleus muscle was isolated and stimulated. Maximum twitch tension, the fatigue index (force of contraction after 2 minutes of continuous stimulation/initial force of contraction), maximum recovery, and the number of limbs recovered (ie, limbs that achieve a force of contraction during the recovery period of > 75% of the force of the initial contraction at the start of continuous stimulation) were recorded. Blood vessel density (number of vessels per ***) was determined by immunostaining the soleus muscle with anti-alpha-actin antibody. RESULTS: All values were indexed to the contralateral normal limb. The flap + bFGF group showed significant improvement versus the control group in maximum twitch tension (1.07 +/- 0.13 vs 0.63 +/- 0.12, P < .05), maximum recovery (0.94 +/- 0.05 vs 0.58 +/- 0.05, P < .05), and the number of limbs recovered (5/5 vs 0/6, P < .05). This improved function correlated with increased vessel density (flap + bFGF group, 1.44 +/- 0.11 vs control group, 0.72 +/- 0.01, P < .05). CONCLUSION: Reperfusion of an ischemic limb with a well-vascularized muscle flap and local bFGF infusion promoted increased blood vessel density in distal ischemic muscle. This increased vascularity was associated with restoration of otherwise impaired muscle function. Improved function occurred rapidly (1 week). A transposed muscle flap provided a functional blood supply to the site of maximum ischemia; this could be used to salvage otherwise nonreconstructible ischemic limbs.

Angiogenesis Inducing Agents↗
PubMed2002

Large vessel aneurysms in Wegener's granulomatosis.

Large vessel aneurysm is not a classical finding in Wegener's granulomatosis. We describe a case report of WG complicated by subclavian artery aneurysm and review the literature on large-vessel and medium-vessel aneurysms in WG. The involved arteries included the aorta and the hepatic, renal, and left gastric arteries. In all but one case, abdominal pain was the presenting symptom. Treatment included medical and vascular interventions. In two patients, the involved vessel ruptured, leading to massive hemorrhage and death. We concluded that unexplained abdominal pain or extremity ischemia in patients with WG should alert the physician to the possibility of a large-vessel or medium-vessel aneurysm.

Aneurysm↗
PubMed1997

Conditional switching of vascular endothelial growth factor (VEGF) expression in tumors: induction of endothelial cell shedding and regression of hemangioblastoma-like vessels by VEGF withdrawal.

We have recently shown that VEGF functions as a survival factor for newly formed vessels during developmental neovascularization, but is not required for maintenance of mature vessels. Reasoning that expanding tumors contain a significant fraction of newly formed and remodeling vessels, we examined whether abrupt withdrawal of VEGF will result in regression of preformed tumor vessels. Using a tetracycline-regulated VEGF expression system in xenografted C6 glioma cells, we showed that shutting off VEGF production leads to detachment of endothelial cells from the walls of preformed vessels and their subsequent death by apoptosis. Vascular collapse then leads to hemorrhages and extensive tumor necrosis. These results suggest that enforced withdrawal of vascular survival factors can be applied to target preformed tumor vasculature in established tumors. The system was also used to examine phenotypes resulting from over-expression of VEGF. When expression of the transfected VEGF cDNA was continuously "on," tumors became hyper-vascularized with abnormally large vessels, presumably arising from excessive fusions. Tumors were significantly less necrotic, suggesting that necrosis in these tumors is the result of insufficient angiogenesis.

Animals↗
PubMed2001

Leukotriene metabolism by intrapulmonary vessels of newborn lambs: effect of platelet-activating factor.

Leukotrienes (LTs) are potent vasoconstrictors in the pulmonary circulation. We investigated LTB4 and LTE4 metabolism by intrapulmonary arteries and veins of 2 to 9 days old lambs (n = 6). Paired vessels were incubated under baseline, and stimulated conditions. LTB4 and LTE4 were extracted from media, quantfied by enzyme-linked immunosorbent assay (ELISA), normalized to tissue weight and presented as ng/mg tissue (means +/- SEMs). In arteries, baseline synthesis of LTB4 was 0.15+/-0.20 and increased to 0.96+/-0.04 on stimulation with 1.0 micromol/L A2318, and 1.74+/-0.25 with 0.1 mmol/L arachidonic acid (AA). In veins the corresponding values were 0.28+/-0.10, 2.50+/-0.51, and 5.36+/-0.70. Baseline production of LTB4 was higher in veins. LTE4 synthesis in arteries was 0.25+/-0.02, which increased to 0.42+/-0.05 with A23187, and further to 0.69+/-0.06 with AA. The corresponding values in veins were 0.23+/-0.05, 0.74+/-0.09, and 1.56+/-0.28. Baseline metabolism of LTE4 by the vessels was not different. Furthermore, stimulation of vessels with 50 nmol/L PAF led to over 3-fold increase in LTB4 and LTE4 metabolism by the vessels. Smooth muscle cells stimulated with A23187 metabolized LTB4 and LTC4, which was sequentially catabolized to LTD4 and LTE4. Generally, stimulated veins, whether vessels or smooth muscle cells, metabolized more leukotrienes. The selective 5-lipoxygenase inhibitor, AA-861, significantly attenuated synthesis of both leukotrienes. Western analysis of membrane protein showed gReater expression of 5-lipoxygenase in stimulated veins. Our data show that veins produce more leukotrienes due to greater expression of 5-lipoxygenase in the vessels, and suggest that veins of newborn lamb lungs may be more susceptible to LT-induced vascular reactivity in the pulmonary circulation.

Animals↗
PubMed1991

The influence of afferent lymphatic vessel interruption on vascular addressin expression.

Tissue-selective lymphocyte homing is directed in part by specialized vessels that define sites of lymphocyte exit from the blood. These vessels, the post capillary high endothelial venules (HEV), are found in organized lymphoid tissues, and at sites of chronic inflammation. Lymphocytes bearing specific receptors, called homing receptors, recognize and adhere to their putative ligands on high endothelial cells, the vascular addressins. After adhesion, lymphocytes enter organized lymphoid tissues by migrating through the endothelial cell wall. Cells and/or soluble factors arriving in lymph nodes by way of the afferent lymph supply have been implicated in the maintenance of HEV morphology and efficient lymphocyte homing. In the study reported here, we assessed the influence of afferent lymphatic vessel interruption on lymph node composition, organization of cellular elements; and on expression of vascular addressins. At 1 wk after occlusion of afferent lymphatic vessels, HEV became flat walled and expression of the peripheral lymph node addressin disappeared from the luminal aspect of most vessels, while being retained on the abluminal side. In addition, an HEV-specific differentiation marker, defined by mAb MECA-325, was undetectable at 7-d postocclusion. In vivo homing studies revealed that these modified vessels support minimal lymphocyte traffic from the blood. After occlusion, we observed dramatic changes in lymphocyte populations and at 7-d postsurgery, lymph nodes were populated predominantly by cells lacking the peripheral lymph node homing receptor LECAM-1. In addition, effects on nonlymphoid cells were observed: subcapsular sinus macrophages, defined by mAb MOMA-1, disappeared; and interdigitating dendritic cells, defined by mAb NLDC-145, were dramatically reduced. These data reveal that functioning afferent lymphatics are centrally involved in maintaining normal lymph node homeostasis.

Animals↗
PubMed1981

On connecting large vessels to small. The meaning of Murray's law.

A large part of the branching vasculature of the mammalian circulatory and respiratory systems obeys Murray's law, which states that the cube of the radius of a parent vessel equals the sum of the cubes of the radii of the daughters. Where this law is obeyed, a functional relationship exists between vessel radius and volumetric flow, average linear velocity of flow, velocity profile, vessel-wall shear stress, Reynolds number, and pressure gradient in individual vessels. In homogeneous, full-flow sets of vessels, a relation is also established between vessel radius and the conductance, resistance, and cross-sectional area of a full-flow set.

Animals↗
PubMed1990

Experimental verification of bioheat transfer theories: measurement of temperature profiles around large artificial vessels in perfused tissue.

The verification of thermal models for use in hyperthermia treatment planning is essential. We investigated the heat transfer between a single vessel and the surrounding vascularised tissue, comparing the conventional bioheat transfer theory and the recently developed keff model using analytical and numerical methods. A plastic tube inserted into the tissue of an isolated perfused organ served as an artificial vessel. This enabled us to vary the blood flow in the vessel and in the tissue independently. The organ used was a bovine kidney, turned into a perfused tissue phantom using an alcohol fixation technique. The temperature profile within the tissue was mapped with constantan-manganin thermocouple wire sensors with a total diameter of 50 microns. The temperature profile relative to the temperature difference between the vessel and organ was measured; increased perfusion caused a reduction of the vessel wall temperature but did not affect the width of the profile. Studying the transient tissue temperature after a step-wise change of the blood temperature in the vessel revealed a faster diffusion of heat at higher perfusion rates. These facts are in accordance with the keff model, but not with the conventional heat-sink theory.

Animals↗
PubMed2003

Novel intracorporeal vascular knot applier for large vessel ligation in laparoscopic surgery: experience in pigs and preliminary clinical use.

BACKGROUND AND PURPOSE: We designed an intracorporeal knot applier for the ligation of large vessels laparoscopically. The aim of this study was to assess the efficacy and efficiency of this method to control large vessels in pigs. MATERIALS AND METHODS: Six pigs with mean body weight of 28 kg (range 26-30 kg) were enrolled. The standard transperitoneal laparoscopic set-up was established with 15 mm Hg of pneumoperionteum. The right renal hilum was mobilized, and the renal artery and renal vein were separated. A 5-cm segment of inferior vena cava with the right renal vein was skeletonized laparoscopically. Assisted by the novel knot applier, 3-0 silk was used to ligate the renal artery, renal vein, and inferior vena cava. The time required to accomplish these ligatures was recorded. Two intracorporeal knots were applied 5 mm apart, and the vessels were divided between the knots. The knot strength was assessed by measuring the maximal intraluminal pressure required to blast out the knot using gas insufflation. RESULTS: The diameters (mean +/- SD) of the porcine inferior vena cava, renal artery, and renal vein were 11.1 +/- 0.7, 2.9 +/- 0.3, and 4.9 +/- 0.3 mm, respectively. The knotting time was 58.9 +/- 8.6, 57.5 +/- 6.6, and 59.1 +/- 6.3 seconds for these vessels, respectively. No bleeding occurred when the vessels were divided. The average pressure needed to withstand the blast out of the ligature on the inferior vena cava, renal artery, and renal vein was 213.3 +/- 32.7 (range 165-250), 227.5 +/- 14.7 (range 210-250), and 210.8 +/- 21.5 (range 180-240) mm Hg, respectively. CONCLUSIONS: The novel intracorporeal knot applier was easy to use when making a ligature on vessels of different sizes and different wall thicknesses. The time required for making a ligature was short, and the knot was secure enough to withstand a vascular pressure higher than ordinary blood pressure. The laparoscopic device is inexpensive with great potential of being used as a secure vascular ligature provider.

Animals↗
PubMedDate not supplied

PlasmaKinetic bipolar vessel sealing: burst pressures and thermal spread in an animal model.

BACKGROUND AND PURPOSE: Laparoscopic bipolar instruments are commonly employed to cauterize and divide tissue. A next-generation bipolar device has been developed that employs vapor pulse coagulation energy. We assessed the vessel-sealing capability of this device and quantified thermal spread during application. MATERIALS AND METHODS: Bilateral laparoscopic nephrectomy was performed on six common swine >25 kg. Five-millimeter clips and surgical staplers (US Surgical, Norwalk, CT) were utilized to perform nephrectomy on one side, while the Gyrus PlasmaKinetic bipolar device (Minneapolis, MN) was employed for the contralateral nephrectomy. Vessel-sealing capabilities were assessed via burst-pressure studies. The extent of thermal spread was measured after tissue fixation and hematoxylin and eosin staining. RESULTS: Surgical clips/vascular staplers adequately controlled/sealed renal hilar vessels with burst pressures nearing 300 mm Hg. The Gyrus bipolar device reliably sealed and divided renal arteries <or=5 mm with burst pressures averaging 291 mm Hg. Renal arteries above this size were not consistently sealed, but, with the exception of one technical error, renal veins of all sizes (3-12 mm) were reliably controlled (average burst pressure 288 mm Hg). Histologic evidence of thermal spread extended an average of 3.6 mm from the cut edges of arteries and 3.4 mm from the edges of veins. CONCLUSIONS: The Gyrus PlasmaKinetic bipolar device is capable of reliably sealing/ dividing arteries as large as 6 mm, although we recommend restricting its use to vessels no larger than 5 mm in diameter to allow a safety margin. In addition, porcine renal veins of all sizes are adequately controlled. These sealed vessels are able to withstand pressures approaching 300 mm Hg. Thermal spread affects only the area surrounding the divided vessel. Further clinical studies are warranted.

Animals↗
PubMed2006

Differential response of arteries and veins to bipolar vessel sealing: evaluation of a novel reusable device.

BACKGROUND: A variety of energy-based techniques for arterial and venous vessel ligation have recently been introduced. Using a porcine model we studied the efficacy of the novel reusable BiClamp versus the standard disposable LigaSure bipolar vessel sealing device. We also compared whether arteries respond differently than veins upon sealing. MATERIALS AND METHODS: In five Swabian Hall pigs, splenectomy and nephrectomy were performed using two different bipolar vessel sealing devices. Measurements of the sealed arteries and veins (diameter 2-7 mm) included rate of seal failure, burst strength, and heat-associated vascular wall morphologic appearance. An additional three animals underwent splenectomy, salpingo-oophorectomy, and small bowel resection, and vessel seals were studied histologically after a seven-day survival period for vessel wall fusion, inflammation, and fibrous organization. RESULTS: Sealing was highly successful, with only one seal failure overall and thus no difference between the two instruments analyzed. The burst pressures of BiClamp-sealed arteries (842 +/- 117 mm Hg) did not differ from that of arteries sealed with LigaSure (856 +/- 102 mm Hg), but were significantly higher than the burst pressures of veins (155 +/- 26 and 216 +/- 71 mm Hg, respectively) (P < 0.05). Independent of the sealing device used, thermal spread was found increased in veins compared to arteries. Histologic analysis after seven days revealed appropriate healing of the vessel wall, including thrombus fibrosis, fibroblast proliferation, and collagen deposition. With both devices, however, the venous but not the arterial walls still presented with massive inflammatory cell infiltrates. CONCLUSION: Our study indicates that the BiClamp device is as appropriate as the LigaSure instrument to successfully ligate 2-7 mm arteries and veins, demonstrating supraphysiological bursting strengths and adequate lumenal fusion healing. However, veins are more prone to collateral tissue damage and inflammatory wall infiltration.

Animals↗
PubMed2006

Feasibility of vitrification as a storage method for tissue-engineered blood vessels.

It is well established that, in multicellular systems, conventional cryopreservation results in damaging ice formation, both in the cells and in the surrounding extracellular matrix. As an alternative to conventional cryopreservation, we performed a feasibility study using vitrification (ice-free cryopreservation) to cryopreserve tissue-engineered blood vessels. Fresh, frozen, and vitrified tissue-engineered blood vessels were compared using histological methods, cellular viability, and mechanical properties. Cryosubstitution methods were used to determine the location of ice in conventionally cryopreserved engineered vessels. Ice formation was negligible (0.0 +/- 0.0% of vessel area) in the vitrified specimens, and extensive (68.3 +/- 4.5% of vessel area) in the extracellular matrix of frozen specimens. The metabolic assay and TUNEL staining results indicated that vitrified tissue had similar viability to fresh controls. The contractility results for vitrified samples were >82.7% of fresh controls and, in marked contrast, the results for frozen samples were only 10.7% of fresh controls (p < 0.001). Passive mechanical testing revealed enhanced tissue strength after both freezing and vitrification. Vitrification is a feasible storage method for tissue-engineered blood vessel constructs, and their successful storage brings these constructs one step closer to clinical utility.

Animals↗