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At least 973 records · Page 54Linked to original sources
PubMed2002

The mechanisms of blood vessel closure in humans by the application of ultrasonic energy.

BACKGROUND: The use of the ultrasonically activated scalpel (UAS) for vessel closure has attained widespread acceptance in many surgical fields. The aim of our study was to investigate the electron microscopic changes to the blood vessels after the application of UAS. METHODS: We collected 10 arterial and 10 venous segments from vessels that had previously been closed by UAS during abdominal operations. The samples were then prepared for ultramicroscopic analysis. Pathological changes in the lumen and the three wall layers of the blood vessel were examined under scanning and transmission electron microscopy. RESULTS: All of the vessel segments showed similar changes: the presence of a blood clot, endothelial cell condensation, coagulative necrosis of the wall, and charring of the vessel at its tip. The edge of the cut vessel were closed by the coagulation bond, which was tied up by collagen fibrils escaped from denaturation. CONCLUSION: When ultrasonic energy is applied to tissues, it changes their structure so as to make a new extracellular matrix.

Cystic Duct↗
PubMed2000

Laparoscopic orchiopexy without division of the spermatic vessels: can it be considered the procedure of choice in cases of intraabdominal testis?

BACKGROUND: Several surgical procedures have been described for the management of nonpalpable testis. Following a vast experience with a complete laparoscopic two-stage Fowler-Stephens procedure, we report our experience with laparoscopic orchiopexy performed without dividing the spermatic vessels. METHODS: Over a 24-month period, 70 boys with nonpalpable testes (72 overall) underwent laparoscopic diagnostic exploration. Twenty patients (27.8%) of this series who showed an intraabdominal testis underwent laparoscopic orchiopexy without sectioning the spermatic vessels. In seven cases, the testis was just proximal to the internal inguinal ring; in 13, it was in the high intraabdominal position. The technique consisted in sectioning the gubernaculum (when present), opening the peritoneum laterally to the spermatic vessels, and mobilizing the testicular vessels and the vas deferens in a retroperitoneal position for 8-10 cm. The testis was then brought down into the scrotum through the internal inguinal ring (11 cases), if this was open, or through a neo-inguinal ring (nine cases) created medially to the epigastric vessels. In every case, we closed the inguinal ring at the end of the operation using one or two detached sutures. RESULTS: Operating time ranged between 40 and 75 min (median, 55). All the testes were successfully brought down into the scrotum. We had only one (5%) intraoperative complication. In the second patient treated with this procedure, there was an iatrogenic rupture of the spermatic vessels due to excessive traction. CONCLUSION: On the basis of our experience, we believe that laparoscopic orchiopexy without division of the spermatic vessels should be the treatment of choice in the management of nonpalpable testes, because it does not affect normal testicular vascularization and is minimally invasive. A blunt dissection and a delicate manipulation of the testis without excessive traction are the best ways to avoid any kind of complication.

Child↗
PubMed2003

Pronounced arterial collateralization was induced after permanent rat cerebral four-vessel occlusion. Relation to neuropathology and capillary ultrastructure.

The present study investigates chronic changes in cerebral arterial vessel system, microvasculature, and brain histopathology using an adult rat model based on permanent and stepwise occlusion of four cerebral vessels. Digital subtraction angiography (DSA) was performed to study chronic changes in arterial cerebral vessel system after permanent vessel occlusion. Long-lasting functional changes such as NMDA-, AMPA- and GABA(A)-receptor binding were detected in hippocampus and dentate gyrus using autoradiography. Structural changes in cerebral capillaries were investigated using light- and electron microscopy. Chronic cerebral oligemia did not cause any significant changes in the densities of excitatory glutamate and inhibitory GABA(A) receptors. By electron microscopy we could document, however, that most capillaries in vessel-occluded animals shrank, the endothelial cells were prominent with enlarged nuclei and increased cytoplasm, and the basal membrane was thickened. In contrast to the degenerative changes in brain capillaries, pronounced arterial collateralization was disclosed by DSA after chronic brain vessel occlusion. The model of chronic occlusion of four cerebral vessels is characterized by capillary degeneration and arterial collateralization proceeding in parallel. Thus, this rat model may be useful in investigations of long-lasting compensatory mechanisms contributing to cerebrovascular or neurodegenerative disorders.

Angiography, Digital Subtraction↗
PubMed2003

[Evaluation of the lower leg vessels before microsurgical fibula transfer. Magnetic resonance angiography versus digital subtraction angiography].

BACKGROUND: Since the introduction of the fibula flap by Taylor in 1975, and its first application in the lower jaw by Hidalgo in 1989, it has become an option of first choice in mandibular reconstruction of large oromandibular defects. Perfusion of the osteomyocutaneous fibula transplant is based on the peroneal artery. To avoid postoperative ischaemia of the lower leg after sacrificing this artery, especially in smokers, adequate perfusion must be guaranteed preoperatively by radiological evaluation. Progress in the field of magnetic resonance angiography (MRA) enables an increasing number of primary non-invasive evaluations of vessels. The aim of this prospective study was to answer the question of whether MRA enables a accurate representation of anatomical variation and pathological stenoses of the lower leg vessels and can therefore replace conventional digital subtraction angiography (DSA). MATERIALS AND METHODS: We carried out conventional DSA of the lower leg before raising a fibula transplant and postoperative MRA with contrast medium in a prospective study with 15 patients. Vessels were assessed for atherosclerotic, occlusive or hypoplastic changes and anatomical variations by three radiologists. RESULTS: High resolution of MRA enables a reliable judgement of the lower leg vessels. Hypoplastic vessels, stenoses, occlusion or atherosclerotic changes of the vessels could definitely be detected by MRA just as by DSA. Thus, all patients without these diagnosed contraindications could be operated successfully. CONCLUSION: MRA of the lower leg enables a definitive determination of the vessel quality and the site of preference for harvesting the flap. Because MRA is a low risk procedure, can be carried out on an outpatient basis and causes no radiation load, it should be preferred to conventional DSA.

Adult↗
PubMed2004

Pressure-controlled vascular clamp: a novel device for atraumatic vessel occlusion.

Morphological vessel injury after clamping has been an important problem in vascular surgery. Although various techniques have been employed to occlude a vessel during a surgical procedure, a complete, atraumatic occlusion method has not yet been developed. In the present study, we describe use of a novel pressure-controlled and balloon-jawed vessel clamp to provide atraumatic vessel occlusion. We compared its traumatic effect on femoral arteries with that resulting from use of a conventional De Bakey vascular clamp in a canine model. During surgical application, our clamp provided complete vessel occlusion with no oozing in distal arteriotomy. On histological examination of the clamped vessel segments, we observed no destruction of the vessel wall, compared to widespread injury of the De Bakey vascular clamp. Despite some difficulties in application, we think this technique could be a promising method for vascular procedures.

Angioplasty, Balloon, Coronary↗
PubMed1975

Left ventricular function in patients with and without myocardial infarction and one, two or three vessel coronary artery disease.

Ninety-six patients with chest pain were studied to determine the relation between left ventricular function and severity of coronary artery disease in patients with and without a history of myocardial infarction. Coronary arteriography was performed obtaining cineangiograms (60 frames/sec) and large roll film angiograms (2 to 6 frames/sec) for precise definition of the coronary anatomy. The criteria for diagnosis of myocardial infarction were a typical history, a rise and fall in serum glutamic oxaloacetic transaminase levels and evolutionary S-T segment changes associated with Q waves of at least 0.03 second. Left ventricular function was assessed by measurement of left ventricular end-diastolic pressure and volume, and left ventricular ejection fraction, mass and compliance. Fifteen patients had normal findings; 81 were classified according to number of diseased vessels and presence or absence of myocardial infarction. There were no group differences in age or heart rate. Left ventricular end-diastolic pressure was abnormally increased in patients with three vessel disease and myocardial infarction. Left ventricular end-diastolic volume was increased and the ejection fraction was reduced in patients in each vessel disease group with myocardial infarction. Although ejection fraction was reduced in patients with three vessel disease without myocardial infarction, it was further reduced when infarction occurred. Left ventricular mass increased in patients with three vessel disease with or without myocardial infarction. Values for ventricular compliance were reduced in all patients with myocardial infarction and were lower in those with two and three vessel disease and infarction than in those with two and three vessel disease without infarction. These findings suggest that a previous history of myocardial infarction needs to be considered together with anatomic abnormalities of the coronary arteries in assessing cardiac performance in patients with ischemic heart disease, a previous myocardial infarction significantly alters left ventricular performance; the ejection fraction is a more sensitive measurement of left ventricular function than left ventricular end-diastolic pressure or volume.

Adult↗
PubMed1985

Improved accuracy of the exercise electrocardiogram: identification of three-vessel coronary disease in stable angina pectoris by analysis of peak rate-related changes in ST segments.

Exercise electrocardiography has relatively poor specificity and predictive accuracy for 3-vessel coronary artery disease (CAD) when conventional diagnostic criteria are used. However, electrocardiographic evaluation using linear regression analysis of the heart-rate (HR)-related change in ST-segment depression (ST/HR slope) is reported to accurately distinguish patients with from those without CAD, and to accurately separate patients with 1-, 2- and 3-vessel CAD. To assess the applicability of this method and to compare it with conventional interpretation, retrospective evaluation of 50 patients in whom exercise electrocardiography and coronary cineangiography had been performed for suspected CAD was conducted using a modified ST/HR slope analysis limited to leads V5, V6 and aVF. Eighteen patients had 3-vessel, 22 had 2-vessel, 6 had 1-vessel and 4 had no CAD. Standard electrocardiographic criteria (1 mm or more of horizontal or downsloping ST depression) identified 3-vessel CAD with a sensitivity of 78%, specificity of 56% and positive predictive value of only 50%. Peak ST/HR slope criteria (greater than or equal to 6.0 microV/beat/min) identified 3-vessel CAD with a sensitivity of 78%, specificity of 97% and positive predictive value of 93%. The overall test accuracy using measured peak ST/HR slope was 90%, compared with 64% for standard ST-depression criteria. In conclusion, analysis of the peak ST/HR slope can greatly improve the diagnostic accuracy of exercise electrocardiography, and further prospective study of this method is indicated.

Adrenergic beta-Antagonists↗
PubMed1991

Effects of alpha,beta-methylene ATP on resistance and capacitance blood vessels of the cat intestinal circulation; a comparison with other vasoconstrictor agents and sympathetic nerve stimulation.

The autoperfused intestinal circulation of pentobarbitone anaesthetized cats was used to study the effects of alpha,beta-methylene ATP (1-100 micrograms i.a.) on pre-capillary resistance vessels and post-capillary capacitance (venous) blood vessels in comparison with other vasoconstrictor agents (also given i.a.) and the effects of sympathetic nerve stimulation (0.25-16 Hz). All cats were treated with atropine and propranolol. alpha,beta-Methylene ATP, noradrenaline and sympathetic nerve stimulation all caused dose- or frequency-dependent constriction of both resistance and capacitance vessels. alpha,beta-Methylene ATP was particularly active on capacitance vessels causing a greater constriction than either noradrenaline or sympathetic nerve stimulation. In comparison, angiotensin II and vasopressin caused a selective constriction of resistance vessels and prostaglandin F2 alpha a selective constriction of capacitance vessels. The results demonstrate that functional P2x purinoceptors are present on both arterial and venous blood vessels of the cat intestinal circulation.

Adenosine Triphosphate↗
PubMed1991

Microlymphography of spontaneous lymph vessel anastomosis in small bowel transplantation in the rat.

Following small bowel transplantation, new lymph vessel anastomoses form spontaneously. Surgical anastomoses of the lymphatic vessels are unnecessary. The formation occurs in three stages. To the second postoperative day, lymph stays within the lymphatic vessels of the transplant. Following the fourth postoperative day, lymph flows within preexistent adventitial lymphatic vessels along the transplanted mesenteric artery to the arterial anastomosis at the aorta and stops there. From the sixth postoperative day on, lymph crosses the arterial anastomosis for the first time and flows along the recipient's aorta. To the eighth postoperative day a new lymph anastomosis is formed between the adventitia of the aorta and the neighbouring major lymphatic vessels. In the experiments presented here, these are represented by the vasa lymphatica testicularia sinistra of the recipient. Thus, the new anastomosis between lymphatic vessels is complete on the eight postoperative day. These new vessels gradually dilate with time.

Animals↗
PubMed1983

Effects of arachidonic acid and its cyclo-oxygenase and lipoxygenase products on lymphatic vessel contractility in vitro.

Lymphatic vessels exhibit rhythmical contractility in vivo and in vitro and this activity appears to regulate lymph flow. A technique for measuring the circular muscle contractions of isolated bovine mesenteric lymphatic vessel segments has been devised and utilized to study the pharmacological properties of these vessels. Non-contracting lymphatic vessels can be induced to contract rhythmically with a variety of mediators, the most potent being a stable PGH2 analogue (compound U46619), and the leukotrienes B4, C4 and D4 (threshold concentrations in the nanomolar range). Prostaglandin F2 alpha, noradrenaline, serotonin and histamine also elicited rhythmical activity but much higher concentrations were required. PGE2 and PGE1 were potent inhibitors of spontaneous contractions or those induced with U46619. In keeping with the diverse pharmacological effects of the metabolites of arachidonic acid, the addition of arachidonate to an isolated lymphatic vessel generated both stimulatory and inhibitory activities. It is concluded that arachidonic acid products (produced in the lymphatic vessel or entering the vessel in lymph draining the tissues) regulate lymph flow through their effects on lymphatic smooth muscle.

Alprostadil↗
PubMed1984

Lymphatic vessels in the uterine endometrium of virgin rats.

Uteri from four diestrous rats fixed by perfusion were examined histologically for the presence of lymphatic vessels in the endometrium, using 1 micron epoxy sections stained with toluidine blue. For each animal, multiple random sections were prepared from 3 tissue samples. In all sections, lymphatics were readily apparent in the myometrium, being identified by their irregular shape and contents of stained lymph proteins, which contrasted with the clear, empty blood vessels. While similar lymphatics were not seen in the endometrium of most tissue samples, one sample from each of three females revealed a small lymphatic vessel near the bases of the uterine glands, clearly in the endometrium. One of these was followed in serial alternating light and electron microscopic sections. The vessel maintained its relative position to the endometrial glands for a considerable distance, and also joined with two separate branches that appeared along its course. Ultrastructural observations, including a thin endothelium without a continuous basal lamina, the presence of anchoring filaments, and only mononuclear cells and cellular debris in the lumen, confirmed the vessel's identification as a lymphatic. The vessel's size was normally large enough to be followed by light microscopy; however, at some places along its course, the lumen narrowed to such a degree that it was only identifiable ultramicroscopically . These observations refute claims that there are no lymphatic vessels in rodent uterine endometrium, but indicate that they are small and sparsely distributed.

Animals↗
PubMed1988

Neurokinin A in cerebral vessels: characterization, localization and effects in vitro.

Nerve fibres displaying neurokinin A (NKA)-immunoreactivity (IR) were seen in trigeminal nerve cell bodies and around cerebral blood vessels. NKA-positive fibres had the same general distribution as those displaying substance P (SP)-IR. Double or sequential immunostaining revealed coexistence of NKA- and SP-IR in a population of small nerve cell bodies in the trigeminal ganglion and in perivascular nerve fibres of brain vessels; both tachykinins were also noted to coexist with calcitonin gene-related peptide (CGRP)-IR. The presence of NKA- and SP-IR in cerebral vessels from guinea pig was verified by high-performance liquid chromatography and radioimmunochemistry. The levels NKA-IR were higher than those of SP-IR in cerebral vessels of rat, guinea pig and rabbit. In cat, pig, cow and human brain vessels, the levels of NKA- and SP-IR were equal. Major cerebral vessels at the base of the brain contained higher levels of NKA- and SP-IR than pial vessels on the cerebral convexities. Only low levels of NKA-IR and SP-IR were measured in choroid plexus and dura mater. Precontracted isolated arterial segments of middle cerebral (cat), basilar (rabbit, guinea pig and rat) and pial arteries (man) relaxed following the in vitro administration of NKA and SP. The responses occurred in the same concentration range; the IC50 value for NKA was, however, about 10 times higher than that for SP, while the maximum relaxation was equal. In basilar arteries from guinea pig, the peptides NKA, SP and CGRP all induced strong and potent relaxations. There was no evidence that one of the peptides might potentiate the relaxant effects in vitro of another. The present data suggest that NKA, SP and CGRP are costored and can be released together and cooperate in the mediation of vascular reactions in response to activation of the trigemino-cerebrovascular pathway.

Animals↗
PubMed1991

Small-vessel pathology and anastomosis following maxillofacial firearm wounds: an experimental study.

This experiment was designed to provide a biological basis for early reconstruction of maxillofacial defects caused by firearms using free vascularized flap transfer. The pathologic changes of small-vessel injury, injury mechanism, and the feasibility for early anastomosis of these vessels in the maxillofacial region following high-velocity missile wounds were studied. Dogs' faces were wounded by a steel sphere, weighing 0.7 g and 1.03 g, with an initial velocity of 1,300 m/s or 1,500 m/s. Angiography and high-speed x-ray photography were used to record the effect of injury to blood vessels and other tissues. The pathologic changes in the small blood vessels in the wounds were studied by light microscopy (LM) and electron microscopy (EM). Anastomosis of small vessels in the wound was performed at different times after injury. There were temporary cavity effects and small vascular injury in the wounds. The pathologic changes of the small vessels included microthrombus formation, endothelial loss, breaks in the internal elastic layer, and necrosis. Degeneration of cells was found to end 3 cm from the wound edge. Anastomosis of the vessels performed 3 days after injury provided good short-term patency. These results suggest that the operation for repairing facial defects should be performed 3 days after injury.

Animals↗
PubMed1996

Potential adverse effects of high-intensity focused ultrasound exposure on blood vessels in vivo.

The aim of the study was to evaluate the potential adverse effects of high intensity ultrasound exposure on blood vessels during noninvasive focused ultrasound surgery. A hydraulic MR-compatible positioning device was used to manipulate a focused ultrasound transducer (frequency 1.49 MHz, f-number = 0.8) in an MRI scanner. The system was used to sonicate a branch of the femoral artery and vein of 19 rabbits (26 thighs) in vivo at intensity levels above the threshold for transient cavitation; i.e., between 4400 and 8800 W cm-2 with multiple 1 s pulses stepped across the vessels (step size = 0.7 mm). The vessels were located and followed by MR angiography. In 13 rabbits, x-ray angiograms were also performed after the animals were euthanized. The results demonstrated that the 1 s high-intensity exposures caused the arteries to constrict at all exposure levels tested. At the intensity of 5800 W cm-2 and above, the MRI angiogram immediately after the sonications showed no flow. The x-ray angiograms (1-2 h later) showed that the blood vessels were open, but constricted to about 50% or less of their diameter. Both the MR and x-ray angiograms showed that the vessel diameters relaxed toward their initial diameter during the first week after sonication. In five cases, hemorrhage or vessel rupture was caused by the sonication. This study demonstrates that short, high-intensity focused ultrasound exposure can cause vessel spasm and hemorrhage when transient cavitation is present. This condition should be avoided during noninvasive focused ultrasound surgery.

Angiography↗
PubMedDate not supplied

Morphometry of blood vessels in the cortex and germinal plate of premature neonates.

Germinal plate hemorrhage with intraventricular rupture has been a leading cause of morbidity and mortality among premature neonates. Because germinal plate hemorrhage decreases with increasing gestational age, germinal plate vessel size and/or structure may be an important etiologic factor. Electron micrographs of the cortical and germinal plate blood vessels from 13 premature infants ranging in age from 19-37 weeks gestation were studied; vessel, lumena, and endothelial areas were measured using a digitizing tablet. In infants between 25-32 weeks gestation, the germinal plate vessel and lumenal areas were significantly greater than the areas of cortical vessel and lumena. This finding suggests that one of the factors involved in germinal plate hemorrhage is described by LaPlace's law which states that the larger the vessel diameter, the greater the pressure on the vessel wall.

Basement Membrane↗
PubMed2003

Effect of vessel size and shape on experimental flammability limits of gases.

The flammability limits of methane and propane have been measured using cylindrical vessels of various sizes and one spherical vessel. An ac discharge ignition method has been employed. For a cylindrical vessel of small diameter with a large height, the flammability limits are primarily determined by the quenching effect of the wall. For cylindrical vessels of smaller heights, the experimental flammability limits are affected by hot gas accumulation at the vessel ceiling, unburned gas heating, self heating of the incipient flame by the reflection both from walls and ceiling, and the quenching effect of the walls. If the vessel size is large enough so that all these effects become negligible, the experimental values of flammability limits may approach to the values that would be obtained in free space. In order to approach this condition for a cylindrical vessel, it is desirable to use a container at least 30 cm in diameter and 60 cm in height. For comparison purpose, the measurement has also been done using ASHRAE type 12l spherical flask.

Equipment Design↗
PubMed1999

Comparison of vessel dilator and long-acting natriuretic peptide in the treatment of congestive heart failure.

BACKGROUND: Long-acting natriuretic peptide (LANP; proANF 1-30) and vessel dilator (proANF 31-67) enhance sodium and water excretion in healthy human beings. The current investigation was designed to compare the beneficial effects of LANP and vessel dilator in persons with congestive heart failure (CHF). METHODS AND RESULTS: LANP and vessel dilator (100 ng/kg body weight/min, respectively) were given intravenously for 60 minutes to subjects with New York Heart Association class III CHF (n = 17) while their urine volume and sodium and potassium excretion were monitored. Vessel dilator increased urine flow more than 5-fold, which was still increased (P <.001) 3 hours after stopping its infusion. Vessel dilator enhanced sodium excretion 3-fold in subjects with CHF (P <.01), which was still significantly (P <.01) elevated 3 hours after infusion. The effects of LANP were diminished, with urine flow only increasing 2-fold (P <.05). The fractional excretion of sodium increased maximally 6-fold secondary to vessel dilator and 3-fold with LANP. The CHF control patients had no changes in the above parameters. Part of the diminished response to LANP was found to be caused by its rapid decrease in the circulation of individuals with CHF. CONCLUSIONS: These results indicate that vessel dilator has significant beneficial diuretic and natriuretic properties, which are not diminished, whereas the effects of LANP are diminished in human beings with CHF compared with healthy individuals.

Atrial Natriuretic Factor↗
PubMed2002

Photodynamic therapy increases the eligibility for feeder vessel treatment of choroidal neovascularization caused by age-related macular degeneration.

PURPOSE: To report angiographic observations about feeder vessel identification after photodynamic therapy in patients with choroidal neovascularization caused by age-related macular degeneration. DESIGN: Cohort study. METHODS: We analyzed fluorescein and indocyanine green dynamic angiography in 156 eyes of 145 patients before and after photodynamic therapy to identify the feeder vessels of the choroidal neovascular membrane. RESULTS: Before photodynamic therapy one or more feeder vessel could be detected in 35 (22.4%) out of 156 eyes with choroidal neovascularization. Three months after photodynamic therapy, a feeder vessel could be identified in 112 (84.2%) out of 133 eyes with persistent choroidal neovascularization. Among these, 16 eyes received direct laser photocoagulation of the feeder vessel and did not need any further photodynamic therapy. CONCLUSION: Previous photodynamic therapy improves the detection of the feeder vessel of the choroidal neovascularization. A sequential combined therapy (photodynamic and feeder vessel treatment) could be considered as an alternative to multiple photodynamic treatments.

Choroid↗