scholarly journals Venous Segment

2020 ◽  
Author(s):  
Keyword(s):  
Venous Segment

Partial analysis of segmental resistances in intestinal vessels after endotoxin

1962 ◽  
Vol 202 (5) ◽  
pp. 913-918 ◽  
Author(s):  
Maurice W. Meyer ◽  
Maurice B. Visscher
Keyword(s):  
Lethal Dose ◽  
Wall Tension ◽  
Shock State ◽  
E Coli ◽  
Small Vessels ◽  
Control Value ◽  
Partial Analysis ◽  
Subsequent Rise ◽  
Venous Segment ◽  
Intestinal Circulation

Hemodynamic responses of intestinal vascular segments of the dog to intravenous administration of a lethal dose (1 mg/kg) of E. coli endotoxin were investigated. Pressures were measured in large and small vessels of the intestinal and mesentery (small veins 30–60 µ in radius). Vascular radii of submucosal vessels and blood flow were determined. Changes in total resistance in the intestinal circulation after endotoxin were not uniform during the first few minutes, but there was a significant decrease at 10 min and a subsequent rise to the control value after 1 hr. At both 50 and 60 min, the resistance was increased over control in the arterial segment by 50%, increased 500% in the venous segment, and decreased 40% in the segment from small artery to venule. These circumstances would increase capillary pressure and filtration of edema fluid. Increased wall tension at reduced diameter developed in the venous segment during the secondary shock state, whereas relaxation of wall tension occurred in the arteriolar segment.

Radiofrequency ablation for uncomplicated varicose veins

2009 ◽  
Vol 24 (1_suppl) ◽  
pp. 42-49 ◽  
Author(s):  
M S Gohel ◽  
A H Davies
Keyword(s):  
Radiofrequency Ablation ◽  
Varicose Veins ◽  
Clinical Effectiveness ◽  
Standards Of Care ◽  
Venous Reflux ◽  
Vein Occlusion ◽  
Early Return ◽  
Scientific Principles ◽  
Venous Segment

In recent years, minimally invasive endovenous treatments have gained popularity in the treatment of superficial venous reflux. The perceived advantages of endovenous therapy include reduced pain, high vein occlusion rates, and early return to work and normal activities. Endovenous radiofrequency ablation (RFA) involves the delivery of thermal energy from a bipolar catheter to the venous segment to be treated. This technique has been available since 1998 and numerous devices and catheters are now produced. Numerous prospective and randomized studies have compared the effectiveness of RFA with traditional and endovenous procedures. In this article, the available evidence for clinical effectiveness, quality of life and cost gains following endovenous RFA is summarized. The scientific principles behind RFA and technical procedural considerations are discussed and standards of care for the delivery of endovenous RFA are proposed.

Longitudinal Effect of Pressure Drop on the Intima-Media Thickening of the Venous Segment of the Arteriovenous Fistula

2013 ◽  
Author(s):  
Ehsan Rajabi-Jaghargh ◽  
Mahesh K. Krishnamoorthy ◽  
Rupak K. Banerjee
Keyword(s):  
Pressure Drop ◽  
Arteriovenous Fistula ◽  
Dialysis Patients ◽  
Luminal Diameter ◽  
Post Surgery ◽  
Opposite Trend ◽  
Venous Stenosis ◽  
Arteries And Veins ◽  
Venous Segment ◽  
Over Time

Venous stenosis is one of the primary causes of the arteriovenous fistula (AVF) maturation-failure and is characterized by vasoconstriction and significant intima-media thickening (IMT). Although the hemodynamic endpoints are believed to play a crucial role in the pathogenesis of venous stenosis, the exact mechanism behind this is unclear. Our hypothesis is that the changes in the pressure drop over time (Δp′) can influence the remodeling factors in AVFs: changes in luminal diameter (ΔDh) and IMT. Curved (C-AVF; n = 3) and straight (S-AVF; n = 3) AVFs were created between the femoral arteries and veins of 3 pigs. CT-scan and ultrasound were utilized to numerically evaluate the flow field, and thus pressure drop in AVFs at 2D (D: days), 7D, and 28D post-surgery. For each AVF, IMT was also measured at 4 histological blocks along the vein. For the C-AVF, the pressure drop consistently decreased over time (from 18.32 mmHg at 2D to 4.58 mmHg at 28D), while opposite trend was found for the S-AVF (from 12.91 mmHg at 2D to 24.49 mmHg at 28D). The Δp′ was negative at all the histology blocks for C-AVF which showed the reduction in the resistance over time due to dilation (positive ΔDh) and outward hypertrophy of the venous segment (positive ΔDh/IMT). In contrast, Δp′ was mostly positive for the S-AVF which showed the increase in the resistance due to vasoconstriction (negative ΔDh) and inward hypertrophy (negative ΔDh/IMT). Thus, measuring Δp′ at the successive post-surgery time points can provide important information on the remodeling behavior of AVFs. Also, creating AVFs in a surgical configuration that can result in negative Δp′ and thus favorable remodeling could influence the life expectancy of the dialysis patients.

Ultrastructural Study Of Experimental Venous Thrombosis

1981 ◽  
Author(s):  
D P Thomas ◽  
R E Merton ◽  
K F Hiller ◽  
D Hockley
Keyword(s):  
Vessel Wall ◽  
Direct Action ◽  
Venous Stasis ◽  
Endothelial Lining ◽  
Jugular Veins ◽  
Ultrastructural Studies ◽  
Platelet Deposition ◽  
Scanning Electronmicroscopy ◽  
Venous Segment

Venous stasis is known to be a necessary but usually not a sufficient cause of venous thrombogenesis. The nature of the additional factor(s) required is uncertain, but the two most likely candidates are local generation of thrombin and vessel wall damage. Autopsy studies show that most venous thrombi develop in apparently normal vessels, although this evidence is based primarily on light microscopy. If thrombin generation is the additional factor, it is uncertain whether such thrombin acts solely on the blood or also damages the endothelium, leading to platelet deposition on exposed subendothelium. We studied the effect of locally injected thrombin on the jugular veins of rabbits, using transmission and scanning electronmicroscopy. One unit of thrombin was sufficient to clot blood contained in an isolated venous segment within a few minutes. The thrombus so formed was then embolised and autologous 11 indium-labelled platelets were injected. Blood flow was re-established for 30 minutes, following which the venous segment was fixed in situ and removed for study.We found no evidence of significant vessel wall damage, as judged by ultrastructural studies or the deposition of labelled platelets. At least 10 u. of injected thrombin were required before the radioactivity in the thrombosed segment exceeded that found in a control vein. Even then, the endothelial lining appeared intact by electronmicroscopy. Following administration of aspirin (10 mg/kg) there was a marked increase in radioactivity present in the thrombosed venous segment, suggesting that inhibition of vessel wall cyclo-oxygenase had led to increased platelet deposition. We conclude that a fresh stasis thrombus resulting from the direct action of thrombin on platelets and fibrinogen does not damage the endothelium, which appears to be relatively resistant in vivo to even high local concentrations of thrombin.

scholarly journals Diagnosis of stenosis within the popliteal–femoral venous segment upon clinical presentation with a venous ulcer and subsequent successful treatment with venoplasty

2017 ◽  
Vol 5 ◽  
pp. 2050313X1774051
Author(s):  
Emma Dabbs ◽  
Alina Sheikh ◽  
David Beckett ◽  
Mark S Whiteley
Keyword(s):  
Saphenous Vein ◽  
Lower Limb ◽  
Varicose Veins ◽  
Venous Ulcer ◽  
Distal Region ◽  
Duplex Ultrasonography ◽  
Venous Ulceration ◽  
Venous Collaterals ◽  
The Right ◽  
Venous Segment

This case study reports the diagnosis and treatment of a lower limb venous ulcer with abnormal underlying venous pathology. One male patient presented with bilateral varicose veins and a right lower limb ulcer. Upon investigation, full-leg duplex ultrasonography revealed total incompetence of the great saphenous vein in the left leg. In the right leg, duplex ultrasonography showed proximal incompetence of the small saphenous vein, and dilation of the anterior accessory saphenous vein, which remained competent. Incidentally, two venous collaterals connected onto the distal region of both these segments, emerging from a scarred, atrophic popliteal–femoral segment. An interventional radiologist performed venoplasty to this popliteal–femoral venous segment. Intervention was successful and 10 weeks post procedure ulceration healed. Popliteal–femoral venous stenosis may be associated with venous ulceration in some cases and may be successfully treated with balloon venoplasty intervention.

5,6-Epoxyeicosatrienoic acid reduces increases in pulmonary vascular resistance in the dog

1998 ◽  
Vol 275 (1) ◽  
pp. H100-H109 ◽  
Author(s):  
Alan H. Stephenson ◽  
Randy S. Sprague ◽  
Andrew J. Lonigro
Keyword(s):  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Circulation ◽  
Constant Infusion ◽  
Physiological Salt Solution ◽  
Dependent Manner ◽  
Active Tension ◽  
Epoxyeicosatrienoic Acid ◽  
Vascular Beds ◽  
Venous Segment

We recently reported that canine pulmonary microsomes metabolize arachidonic acid to all four regioisomeric epoxyeicosatrienoic acids (EET). 5,6-EET dilates blood vessels in several nonpulmonary vascular beds, often in a cyclooxygenase-dependent manner. The present study was designed to determine whether 5,6-EET can decrease pulmonary vascular resistance (PVR) in the intact pulmonary circulation. In isolated canine lungs perfused with physiological salt solution, a constant infusion of U-46619 (3.28 ± 0.99 nmol/min) increased PVR 62.1 ± 4.5%. Administration of 5,6-EET (10−5 M) into the perfusate reduced the U-46619-mediated increase in PVR by 23.6 ± 6.1%. These effects of U-46619 and 5,6-EET were limited to changes in resistance solely in the pulmonary venous segment. In contrast, venous as well as arterial segmental resistances were increased in 5-hydroxytryptamine (5-HT)-treated lungs. However, in the latter instance, 5,6-EET reduced arterial but not venous segmental resistance. 5,6-EET increased pulmonary PGI2 synthesis from 70.5 ± 18.4 to 675.9 ± 125.4 ng/min. In the presence of indomethacin (10−4 M), 5,6-EET did not increase PGI2 synthesis nor did it decrease U-46619- or 5-HT-mediated increases in PVR. In canine intrapulmonary vessels, 5,6-EET decreased active tension in veins contracted with U-46619. 5,6-EET decreased active tension in arteries but not veins contracted with 5-HT, consistent with results in the perfused lungs. These results demonstrate that 5,6-EET is a vasodilator in the intact pulmonary circulation. Its dilator activity depends on the constrictor agent present, the segmental resistance, and cyclooxygenase activity.

Microvascular pressure profile in intact in situ lung

1992 ◽  
Vol 72 (1) ◽  
pp. 332-339 ◽  
Author(s):  
D. Negrini ◽  
C. Gonano ◽  
G. Miserocchi
Keyword(s):  
Left Atrial ◽  
Pressure Profile ◽  
Parietal Pleura ◽  
Pulmonary Capillary ◽  
Null System ◽  
Pulmonary Capillary Pressure ◽  
Residual Capacity ◽  
Pulmonary Arterial ◽  
Venous Segment

We measured the microvascular pressure profile in lungs physiologically expanded in the pleural space at functional residual capacity. In 29 anesthetized rabbits a caudal intercostal space was cleared of its external and internal muscles. A small area of endothoracic fascia was surgically thinned, exposing the parietal pleura through which pulmonary vessels were clearly detectable under stereomicroscopic view. Pulmonary microvascular pressure was measured with glass micropipettes connected to a servo-null system. During the pressure measurements the animal was kept apneic and 50% humidified oxygen was delivered in the trachea. Pulmonary arterial and left atrial pressures were 22.3 +/- 1.5 and 1.6 +/- 1.5 (SD) cmH2O, respectively. The segmental pulmonary vascular pressure drop expressed as a percentage of the pulmonary arterial to left atrial pressure was approximately 33% from pulmonary artery to approximately 130-microns-diam arterioles, 4.5% from approximately 130- to approximately 60-microns-diam arterioles, approximately 46% from approximately 60-microns-diam arterioles to approximately 30-microns-diam venules, approximately 9.5% from 30- to 150-microns-diam venules, and approximately 7% for the remaining venous segment. Pulmonary capillary pressure was estimated at approximately 9 cmH2O.

Results of venous resections in cancer of the pancreatic head.

2020 ◽  
Vol 38 (15_suppl) ◽  
pp. e16785-e16785
Author(s):  
Oleg I. Kit ◽  
Oksana V. Katelnitskaya ◽  
Andrey A. Maslov ◽  
Aleksey Yu. Maksimov ◽  
Evgeniy N. Kolesnikov ◽  
...  
Keyword(s):  
Pancreatic Head ◽  
Pathological Examination ◽  
Additional Risk Factor ◽  
Incomplete Resection ◽  
Sleeve Resection ◽  
Venous Resection ◽  
Advantages And Disadvantages ◽  
Ductal Pancreatic Adenocarcinoma ◽  
Direct Anastomosis ◽  
Venous Segment

e16785 Background: Studies have shown that pancreaticoduodenal resection (PDR) with resection and reconstruction of the venous segment does not interfere with surgical treatment for ductal pancreatic adenocarcinoma with suspected venous invasion. Venous resection improves survival compared to palliative interventions. However, the advantages and disadvantages of marginal resection, segmental resection with direct anastomosis, and venous segment prosthetics are not reflected. Methods: The study included 52 patients (23 women, 29 men) undergoing PDR with venous resection and reconstruction for cancer of the pancreatic head in 2015-2019. The average tumor size was 3.8 cm. Results: Superior mesenteric vein reconstruction (PTFE grafts) was performed in 17 patients (32.7%), sleeve resection with direct anastomosis - 24 (46.2%), marginal resection - 11 (21.1%). Venous reconstruction was planned in 78.8% of patients before the surgery. In the early postoperative period, thrombosis of the reconstructed zone was developed in two patients (3.8%), bleeding from the pancreatic bed - in one case (1.9%). Postoperative mortality was 5.8% (3 patients). After the final pathological examination, macroscopically incomplete resection was diagnosed only in the group with marginal resection and amounted to 3.8%. Microscopically incomplete resection was diagnosed in 9.6% of the studied preparations (in marginal resection of the vein wall - 3.8%, with direct anastomosis - 1.9%, SMV prosthetics - 3.8%). Most often, R1 resection was detected in the retroperitoneal resection margin (80%). The lowest 1-year survival was observed in the group with marginal resection (36.4%). No significant differences in survival rates were found in patients with direct venous anastomosis (62.5%) and venous prosthetics (64.7%) (RR 1.69; 95% CI 0.69-4.12, p > 0.05). Microscopically complete resection R0 improved the survival (RR 2.7; 95% CI 1.45-5.04, p < 0.05). Planning the venous resection was an additional risk factor affecting the completeness of resection (RR 4.6; CI 95% 1.5-14.5, p > 0.05). Conclusions: Expanding the surgery volume in PDR due to venous resection and reconstruction shows acceptable rates of postoperative morbidity and mortality. Planning the venous resection enhances the results of radical surgery.

Balloon angioplasty: A promising adjunct to arteriovenous fistula creation compared with hydrostatic dilatation in small-caliber cephalic veins

2021 ◽  
pp. 021849232110415
Author(s):  
Santosh K Tiwari ◽  
Rajendra P Basavanthappa ◽  
Ranjith K Anandasu ◽  
Sanjay C Desai ◽  
Chandrasekhar A Ramswamy ◽  
...  
Keyword(s):  
Arteriovenous Fistula ◽  
Balloon Angioplasty ◽  
Duplex Ultrasound ◽  
Primary Patency ◽  
Maturation Time ◽  
Arteriovenous Access ◽  
Dilatation Group ◽  
Stage Renal Disease ◽  
End Stage ◽  
Venous Segment

Background To maintain the patency and longevity of arteriovenous fistula, the availability of a venous segment with adequate diameter is important. In Indian population, many chronic kidney disease patients have poor caliber veins. The study aimed to evaluate the efficacy of hydrostatic dilatation versus Primary balloon angioplasty of small caliber cephalic veins of (≤2.5 mm) preoperatively in terms of patency rate and maturation time of arteriovenous fistula. Methods Patients ( n = 80) with an end-stage renal disease requiring arteriovenous access surgery for hemodialysis with small caliber cephalic veins were randomized into two groups, i.e., hydrostatic dilatation and primary balloon angioplasty, each with 40 patients. All patients underwent a thorough clinical examination as well as duplex ultrasound vein mapping of both upper extremities. Patients were followed up for six months and primary patency, maturation time, and complications were noted. Results Immediate technical success with good palpable thrill was achieved in 97.5% of patients in the primary balloon angioplasty group and 87.5% in the hydrostatic dilatation group. The fistula maturation time in the primary balloon angioplasty group was 34.41 days and 46.18 days in the hydrostatic dilatation group. In the primary balloon angioplasty group, the primary patency of the fistula was 97.5% and 87.5% in the hydrostatic dilatation group, at six months. The arteriovenous fistula functioning rate was 77.5% in the hydrostatic dilatation group as compared to 92.5% in the primary balloon angioplasty group at six months. The incidence of surgical site infection was 5% in the primary balloon angioplasty group as compared to 10% in the hydrostatic dilatation group. Conclusion Primary balloon angioplasty of small caliber cephalic veins (≤2.5 mm) performed prior to arteriovenous fistula creation for hemodialysis is a beneficial procedure.

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