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.

Longitudinal Effect of Wall Shear Stress on the Amount of Intimal-Medial Thickening of Venous Wall in Arteriovenous Fistula

2012 ◽  
Author(s):  
Ehsan Rajabi-Jaghargh ◽  
Prabir Roy-Chaudhury ◽  
Mahesh K. Krishnamoorthy ◽  
Yang Wang ◽  
Rupak K. Banerjee
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Arteriovenous Fistula ◽  
Hemodynamic Parameters ◽  
Temporal Gradient ◽  
Post Surgery ◽  
Venous Stenosis ◽  
Venous Diameter ◽  
Consistent Increase ◽  
Wall Shear

Arteriovenous fistula (AVF) maturation failure is mainly due to venous stenosis characterized by significant amount of intima-media thickening (IMT). Although hemodynamic endpoints are believed to play a crucial role in pathogenesis of venous stenosis, the exact mechanism behind this is unclear. Our hypothesis is that longitudinal (temporal) changes of hemodynamic parameters, specifically wall shear stress (WSS), influences amount of IMT in maturation process of AVF. AVFs were created in curved (C-AVF) and straight (S-AVF) configurations between femoral artery and vein of 3 pigs. CT-scans and ultrasound were utilized to calculate WSS at 2D (D: days), 7D, and 28D post-surgery. IMT was measured at 4 histological blocks along the vein of AVFs. It was found that C-AVF underwent outward remodeling characterized by consistent increase in venous diameter and larger IMT. This remodeling process was governed by negative temporal gradient of WSS (τ′) [−0.99 ± 0.60 dyn/cm2/day]. In contrast, S-AVF underwent inward remodeling characterized by temporal decrease in venous diameter and relatively smaller IMT. This remodeling process was governed by positive τ′ (0.42 ± 0.6 dyn/cm2/day). In summary, temporal gradient of WSS influences IMT. Temporal decrease of WSS in C-AVF resulted in vasodilation and outward growth of wall (favorable to maturation). However, temporal increase in WSS in S-AVF leaded to vasoconstriction and inward growth of wall (detrimental to maturation). Thus, clinically it can be of great importance to surgeons to create AVF in a configuration that can result in favorable hemodynamic parameters and histological end-points.

Spontaneous Bleeding from Collateral Chest Wall Veins Is a Rare Complication of Arteriovenous Fistula with Central Venous Stenosis: A Case Report

2020 ◽  
Vol 25 (1) ◽  
pp. 44-47
Author(s):  
Mohammed Hassan Abdelaty
Keyword(s):  
Arteriovenous Fistula ◽  
Chest Wall ◽  
Rare Complication ◽  
Dialysis Patients ◽  
Central Venous ◽  
Spontaneous Bleeding ◽  
Surgical Ligation ◽  
Central Venous Stenosis ◽  
Venous Stenosis ◽  
Life Threatening

Highlights Dialysis patients with arteriovenous fistula who have central venous stenosis develop collateral veins in the axilla and chest wall. These veins are at risk of spontaneous rupture, and major bleeding may occur. Bleeding should be controlled immediately by using a compression bandage, and patients should be resuscitated with fluids and blood transfusion before surgical ligation of the bleeder. Awareness of this complication and early protection can save the patient from life-threatening hemorrhage.

Cutaneous sensory deficit following post-auricular incision

2011 ◽  
Vol 125 (10) ◽  
pp. 1014-1019 ◽  
Author(s):  
S J Frampton ◽  
M Pringle
Keyword(s):  
Sensory Deficit ◽  
Single Centre ◽  
Primary Surgery ◽  
Post Surgery ◽  
Over Time

AbstractIntroduction:Post-auricular incisions are performed for a range of otological procedures. Anecdotally, many patients suffer some numbness of the pinna or post-auricular skin post-operatively, but for most this appears to reduce with time. This study aimed to investigate this phenomenon.Methods:A single centre, questionnaire-based study was undertaken, assessing the presence of numbness beyond eight months post-surgery, its location, how it changed, and its impact on the patient. Patients whose numbness had resolved provided details of any temporary deficit. Data were acquired for 35 primary and 16 revision procedures.Results and conclusion:Sixty-nine per cent of patients undergoing primary surgery experienced post-operative numbness. Twenty-six per cent had continued numbness after at least eight months' recovery, but only 3 per cent were constantly aware of the deficit. Of those with an ongoing deficit, 78 per cent felt there had been a reduction in the severity, and 67 per cent in the area size, over time. Recovery appeared to be slightly worse in revision cases.

scholarly journals Seroresponse to SARS-CoV-2 vaccines among maintenance dialysis patients over six months

2021 ◽  
Author(s):  
Caroline M Hsu ◽  
Daniel E Weiner ◽  
Harold J Manley ◽  
Gideon N Aweh ◽  
Vladimir Ladik ◽  
...  
Keyword(s):  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Prior History ◽  
Time To Event ◽  
Dialysis Patients ◽  
History Of ◽  
Maximum Titer ◽  
Lower Titer ◽  
Maintenance Dialysis ◽  
Over Time

Background and Objectives: While most maintenance dialysis patients exhibit initial seroresponse to vaccination, concerns remain regarding the durability of this antibody response. This study evaluated immunity over time. Design, setting, participants, and measurements: This retrospective cohort study included maintenance dialysis patients from a midsize national dialysis provider who received a complete SARS-CoV-2 vaccine series and had at least one antibody titer checked after full vaccination. Immunoglobulin G spike antibodies (SAb-IgG) titers were assessed monthly with routine labs beginning after full vaccination and followed over time; the semiquantitative SAb-IgG titer reported a range between 0 and ≥20 U/L. Descriptive analyses compared trends over time by prior history of COVID-19 and type of vaccine received. Time-to-event analyses were conducted for the outcome of loss of seroresponse (SAb-IgG < 1 U/L or development of COVID-19). Cox proportional hazards regression was used to adjust for additional clinical characteristics of interest. Results: Among 1898 maintenance dialysis patients, 1567 (84%) had no prior history of COVID-19. Patients without a history of COVID-19 had declining titers over time. Among 441 BNT162b2/Pfizer recipients, median [IQR] SAb-IgG titer declined from 20 [5.99-20] U/L in month 1 to 1.30 [0.15-3.59] U/L by month 6. Among 779 mRNA-1273/Moderna recipients, median [IQR] SAb-IgG titer declined from 20 [20-20] in month 1 to 6.20 [1.74-20] by month 6. The 347 Ad26.COV2.S/Janssen recipients had a lower titer response than mRNA vaccine recipients over all time periods. In time-to-event analyses, Ad26.COV2.S/Janssen and mRNA-1273/Moderna recipients had the shortest and longest time to loss of seroresponse, respectively. The maximum titer reached in the first two months after full vaccination was predictive of the durability of the SAb-IgG seroresponse; patients with SAb-IgG titer 1-19.99 U/L were more likely to have loss of seroresponse compared to patients with SAb-IgG titer ≥20 U/L (HR 23.9 [95% CI: 16.1-35.5]). Conclusions: Vaccine-induced seroresponse wanes over time among maintenance dialysis patients across vaccine types. Early titers after full vaccination predict the durability of seroresponse.

Introducing a “no-touch” maneuver to manage challenging anastomoses in arteriovenous fistulae

2020 ◽  
pp. 112972982096839
Author(s):  
Efstratios Georgakarakos ◽  
Kalliopi-Maria Tasopoulou ◽  
George S Georgiadis
Keyword(s):  
Surgical Technique ◽  
Arteriovenous Fistula ◽  
Vascular Access ◽  
Surgical Outcome ◽  
Dialysis Patients ◽  
Synthetic Graft ◽  
Arteriovenous Fistulae ◽  
Feeding Tubes

Native arteriovenous fistula or interposition of a synthetic graft for vascular access is crucial for dialysis patients. Optimal surgical technique, microsurgery instrumentation and preventive hemostasis are considered beneficial for a successful surgical outcome. We describe a simple and novel maneuver using soft-feeding tubes to facilitate the manipulation of veins and perform successful anastomoses without using microsurgery instrumentation or vascular clamps during operations for vascular access.

scholarly journals Time evolution of restless legs syndrome in haemodialysis patients

2019 ◽  
Author(s):  
Irene Capelli ◽  
Fabio Pizza ◽  
Marco Ruggeri ◽  
Lorenzo Gasperoni ◽  
Elisa Carretta ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Kidney Transplantation ◽  
Restless Legs Syndrome ◽  
Statistical Significance ◽  
Dialysis Patients ◽  
Restless Legs ◽  
Continuous Form ◽  
Over Time

Abstract Background Restless legs syndrome (RLS) is characterized by an urge to move the extremities, accompanied by paraesthesiae, in the evening and at night. Uraemic RLS, a type of secondary RLS, occurs commonly in chronic kidney disease and end-stage renal disease. Progression of uraemic RLS over time is unclear. Therefore we investigated the prevalence, progression over time, risk factors and impact on survival of uraemic RLS in a cohort of dialysis patients. Methods We reviewed at the 7-year follow-up a cohort of haemodialysis (HD) patients we had previously investigated for RLS, through interviews, validated questionnaires and analysis of demographic and clinical data. Results At the 7-year follow-up, RLS was present in 16% of patients, with a persistence rate of 33%. A correlation was obtained between RLS and older age, diabetes, low albumin and low body mass index. RLS was associated with reduced overall survival (median survival of 3.3 versus 3.7 years), particularly with the continuous form of RLS (1.61 years). There was a higher incidence of myocardial infarction and peripheral vascular disease, although not reaching statistical significance. RLS patients had absolute higher scores in all quality of life domains. A large majority of study patients (96%) reported being symptom-free within a few days or weeks following kidney transplantation. Conclusions The development of RLS, especially the continuous form, in patients undergoing HD has important consequences associated with decreased survival. Our results indicated an association between uraemic RLS and ageing, diabetes and malnutrition. Considerable efforts should be focused on the treatment of RLS, since it significantly and persistently impacts the quality of life of HD patients. Kidney transplantation could represent an effective treatment option for that RLS impacts on dialysis patients' quality of life, thus confirming the secondary nature of RLS in most HD patients.

scholarly journals Dietary changes in early-stage breast cancer patients from pre-surgery and over the 12 months post-surgery

2020 ◽  
Vol 125 (2) ◽  
pp. 172-182
Author(s):  
Sonja H. Brunvoll ◽  
Inger Thune ◽  
Gro F. Bertheussen ◽  
Frøydis Fjeldheim ◽  
Vidar G. Flote ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Dairy Products ◽  
Early Stage ◽  
Processed Meat ◽  
Breast Cancer Patients ◽  
Food Diary ◽  
Dietary Changes ◽  
Post Surgery ◽  
Over Time

AbstractThe time after a breast cancer diagnosis is a potential period for making positive dietary changes, but previous results are conflicting. The main aim of the present study was to study breast cancer patients’ dietary changes during the 12 months post-surgery and from 12 months pre-surgery to 12 months post-surgery with repeated administration of a 7-d pre-coded food diary and an FFQ, respectively. Women (n 506), mean age 55·3 years diagnosed with invasive breast cancer (stages I and II), were included. The dietary intake was quite stable over time, but the intake was lower for energy (0·3 and 0·4 MJ/d), alcohol (1·9 and 1·5 g/d) and vegetables (17 and 22 g/d) at 6 months than 3 weeks post-surgery (food diary) and at 12 months post-surgery than pre-surgery (FFQ), respectively. Furthermore, energy percentage (E%) from carbohydrates increased between 0·8 and 1·2 E% and E% from fat decreased between 0·6 and 0·8 E% over time, measured by both dietary assessment methods. We observed a higher intake of dairy products (11 g/d) at 6 months post-surgery (food diary), and a lower intake of dairy products (34 g/d) and red and processed meat (7·2 g/d) at 12 months post-surgery (FFQ). Moreover, 24 % of the patients claimed they made dietary changes, but mostly they did not change their diet differently compared with those patients who claimed no changes. In conclusion, breast cancer patients reported only minor dietary changes from 12 months pre-surgery and during the 12 months post-surgery.

scholarly journals Post-anastomotic venous stenosis after Optiflow deployment: An unexpected outcome

2019 ◽  
Vol 7 ◽  
pp. 2050313X1985100
Author(s):  
Ziad Al Adas ◽  
George Haddad ◽  
Bhavin C Patel ◽  
Lalathaksha Kumbar ◽  
Baha Al-Abid ◽  
...  
Keyword(s):  
Arteriovenous Fistula ◽  
End Stage Renal Disease ◽  
Hypertensive Nephropathy ◽  
New Device ◽  
The Past ◽  
Venous Stenosis ◽  
Stage Renal Disease ◽  
End Stage ◽  
Unexpected Outcome ◽  
First Time

Arteriovenous fistula failure represents a major cause of hospitalization and a significant economic burden for end-stage renal disease patients on hemodialysis. The Optiflow (Bioconnect Systems Inc., Ambler, PA) is a new device developed to improve arteriovenous fistula outcomes and decrease failure rates by reducing the risk of stenosis and improving maturation rates. This case report describes a 50-year-old male with hypertensive nephropathy on dialysis who had multiple arteriovenous fistula failures in the past. He was scheduled to undergo brachiocephalic fistula construction using the Optiflow device. After 8 months of use, the new fistula developed a peri-anastomotic venous stenosis, just distal to the Optiflow device. To our knowledge, this is the first time such a complication has been reported.

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