Venous Distensibility Research Articles

Background Arteriovenous-fistula (AVF) are crucial for hemodialysis access, yet they frequently experience early failure. While studies have identified potential patient and clinical risk factors, these findings remain inconsistent. This inconsistency might be attributed to the varying definitions of “early failure”. Our retrospective cohort study aimed to evaluate how common risk factors predict four frequently early-failure criteria: thrombosis/stenosis, <500 ml/min blood flow, <5 mm vein diameter, and ≥6 mm deep vein. We also assessed how well these risk factors predict early failure defined as meeting at least one of these criteria. Additionally, we examined the predictive ability of vein-distensibility, a previously overlooked factor in AVF failure. Methods Consecutive patients with first-time AVF employing standard minimum preoperative artery- and vein-diameters (1.8–2.0 mm) who underwent first Doppler-ultrasound (DUS) at ≤4 months in 2016–2022 were identified. Early AVF failure was defined as the presence of at least one of the following conditions on the first DUS: poor blood flow (Qa), poor vein diameter, poor vein depth, and thrombosis/stenosis. Factors associated with early AVF failure were explored with multivariate analyses. Results 105 patients were eligible and 63 (60%) had an early AVF failure. The only strong predictor of early failure was low vein-distensibility (Odds ratio = 0.57, 95% confidence intervals [CIs] = 0.38–0.83, p = 0.005). Female sex only predicted too-deep veins (Odds ratio = 14.29, 95% CIs = 2.00–100, p = 0.024). Conclusions venous distensibility may be a useful early-failure determinant when minimum preoperative vessel-diameter limits are met. Moreover, the female sex is associated with too-deep AVF veins.

Synthetic vascular grafts overcome some challenges of allografts, autografts, and xenografts but are often more rigid and less compliant than the native vessel into which they are implanted. Compliance matching with the native vessel is emerging as a key property for graft success. The current gold standard for assessing vessel compliance involves the vessel's excision and ex vivo biaxial mechanical testing. We developed an in vivo method to assess venous compliance and distensibility that better reflects natural physiology and takes into consideration the impact of a pressure change caused by flowing blood and by any morphologic changes present. This method is designed as a survival procedure, facilitating longitudinal studies while potentially reducing the need for animal use. Our method involves injecting a 20 mL/kg saline bolus into the venous vasculature, followed by the acquisition of pre and post bolus 3D angiograms to observe alterations induced by the bolus, concurrently with intravascular pressure measurements in target regions. We are then able to measure the circumference and the cross-sectional area of the vessel pre and post bolus. With these data and the intravascular pressure, we are able to calculate the compliance and distensibility with specific equations. This method was used to compare the inferior vena cava's compliance and distensibility in native unoperated sheep to the conduit of sheep implanted with a long-term expanded polytetrafluorethylene (PTFE) graft. The native vessel was found to be more compliant and distensible than the PTFE graft at all measured locations. We conclude that this method safely provides in vivo measurements of vein compliance and distensibility.

Objective: To evaluate the relation between handgrip strength and vascular characteristics of patients with stage IV and V chronic kidney disease (CKD) under conservative or dialysis treatment. Method: A cross-sectional study with 41 CKD patients in stages IV and V under conservative or dialysis treatment were recruited. Radial artery and cephalic vein diameters, mean radial flow velocity, arterial systolic peak and venous distensibility (ultrasonography), handgrip strength (dynamometry) and non-dominant upper limb forearm circumference (perimetry) were evaluated. Results: A relation between handgrip strength and radial artery diameter was observed at 10cm (R2= 23.4%; β= 10.80; CI95%= 1.38-20.21; p= 0.02) and at 20cm (R2= 21.3%; β=7.44; CI95%= 0.16- 14.72; p= 0.04), and with the distensibility at 20cm (R2= 25.9%; β= 6.24; CI95%= 1.39-11.09; p= 0.01). Conclusion: There was a relation between handgrip strength and vascular diameters and venous distensibility in the proximal forearm segments.

Introduction: Patients with end stage renal disease require hemodialysis. Radiocephalic arteriovenous fistula is the main choice of vascular access in patients who undergo hemodialysis procedure. Physiological vein distensibility is an important aspect in forming a mature arteriovenous fistula. This study aims to analyze the correlation between preoperative distensibility and arteriovenous fistula maturation. Method: Data are collected from end stage renal disease patients in Hasan Sadikin Hospital and RA Habibie Hospitals that will go through radiocephalic arteriovenous fistula procedure during the period of October 2018 to February 2019. Vein distension procedure is performed before the operation and maturation is evaluated four to six weeks after the operation. The comparison of preoperative venous distensibility in two different groups of arteriovenous fistula maturation category is analyzed using chi square test model. Result: This study found that preoperative venous distensibility value affects arteriovenous fistula maturation with a statistical significance (p-value = 0.007), yielding a contingency coefficient of 0.553, and a very strong relation value of 0.782. Conclusion: Preoperative vein distensibility of more than 30% is predictive of successful arteriovenous maturation.

A substantial limitation of dialysis fistulas is their high primary failure rate due to nonmaturation. Various studies have documented that patients with larger vein diameters exhibit reduced risks for nonmaturation. Nevertheless, some patients have small veins. Few studies have focused on patients with small veins. We hypothesize that sufficient venous dilation contributes to fistula maturation. Therefore, we studied the influence of cephalic vein dilation on fistula maturation in patients with small veins.Patients with small cephalic veins (diameter <2 mm) undergoing initial arteriovenous fistulae (AVF) operation were included. A total of 72 patients were enrolled in this study. A prospective study was performed, and the patients were followed for 6 weeks after surgery. Preoperative and postoperative duplex ultrasound mapping of veins was performed, and dilation of the cephalic vein was evaluated.The fistula maturation rate was 44.44%. Multivariate logistic regression analysis revealed a significant relationship between fistula maturation and preoperative cephalic vein dilation. Based on the results of ROC analysis, the fistula maturation rate in patients with vein dilation greater than or equal to the cut-off was 57.14% in the training data set and 54.55% in the testing data set. The independent influencing factors for fistula maturation were used to establish a combined index with logistic regression analysis. The fistula maturation rate in patients with combined indexes greater than or equal to the cut-off was 80.95% in the training data set and 77.78% in the testing data set.Our results demonstrated that preoperative venous dilation was associated with AVF maturation. For patients with small veins, venous distensibility needs to be carefully assessed before surgery, as it may be a better predictor of AVF maturation than venous diameter.

Radio-cephalic arteriovenous fistula is a prototype hemodialysis access with small incidences of infection and distal ischemia, it spares proximal veins for future access use and it helps in the maturation of veins that may be used for more proximal access creations. This access type is prone to higher early failure rates compared to more proximal fistulas and there are unsolved uncertainties regarding exact ultrasound parameters predictive of fistula outcome. Evolution of ultrasound use has yielded several functional parameters that can be measured in addition to anatomical lumen sizes, which remain core parameters on which the decision to construct fistula in radio-cephalic forearm position is based. We propose to use arterial hyperemic response and wall morphology to aid in this decision when radial artery diameter falls in the interval with predictive uncertainty of 1.6-1.9 mm and to use venous flow pattern, respiratory variation, radial artery status and possibly venous distensibility when cephalic vein augmented diameter lies in the borderline interval of 2-2.4 mm. Ultrasound preoperative mapping and planning should be followed by expert surgical technique and several technique modifications of the classical end-to-side approach are possible to enhance operation outcome and diminish the incidence of stenosis most often present at juxta-anastomotic location. In our experience radio-cephalic arteriovenous fistula remains the golden standard for hemodialysis access and preoperative ultrasound the single best imaging modality to plan the operation and predict its success.

Hemiparesis With Hemoptysis

The Impact of Vein Mechanical Compliance on Arteriovenous Fistula Outcomes

Objectives and Design of the Hemodialysis Fistula Maturation Study

Although native radiocephalic arteriovenous fistula (RCAVF) is the best vascular access for hemodialysis (HD), a major obstacle to increase its use is high frequency of fistulas that fail to mature. The aim of this study was to investigate and define cut-off values of morphologic and functional vessel parameters influencing successful RCAVF maturation using ultrasound. A prospective, observational study was performed on 122 patients (66 men) who underwent primary RCAVF creation. Internal diameters of cephalic vein (CVd) and radial artery (ARd), venous distensibility (VD), resistance index (RI) and endothelial function by flow mediated dilatation (FMD) were determined by ultrasound examination before AVF placement. AVF maturation was observed by measuring blood flow (Qa) and CVd 0, 14 and 28 days after creation. Depending on the time when AVFs attained maturity (Qa ≥500 mL/min, CVd ≥5 mm), patients were divided into three groups: (i) successful maturation (after four weeks), (ii) prolonged maturation (within eight weeks) and (iii) failure to mature. Only 11% of patients failed to achieve a mature RCAVF. Successful AVF maturation occurred in 53% of patients and prolonged maturation in 36% of patients. ROC analysis defined the limits ​​of variables relevant for RCAVF success (CVd >1.8 mm, ARd >1.6 mm, VD >0.4 mm). Female sex was associated with prolonged maturation (OR 0.35, 95% CI=0.17-0.72; P=0.005) having a significantly smaller ARd (1.83 vs. 2.01 mm, P=0.01) but better FMD (2981.5 vs. 2689.5, P=0.02) compared to men. ARd ≤1.6 mm, CVd ≤1.8 mm and VD ≤0.4 mm are exact cut-off points, which best predict nonmaturation of RCAVF. Women need extended time for adequately matured AVF.

Arterio-Venous Malformation in the External Ear in Pregnancy

Venous Distensibility as a Key Factor in the Success of Arteriovenous Fistulas at the Wrist

The objectives were to investigate the effects of repeated increments in local intravascular pressure (pressure training; PT) on (1) distensibility in two arm veins, and (2) pain in the arm induced by markedly increased intravascular pressure. Elevation of venous distending pressure (DP) in an arm was induced by placing the subject (n = 8) in a pressure chamber with one arm protruding to the outside via a port in the chamber door, and increasing chamber pressure. During 5 weeks, venous DP in one arm was repeatedly (3 × 40 min/week) increased (65-105 mmHg). Pressure-distension relationships were determined in the brachial and cephalic veins by measuring diameter changes by ultrasonography during stepwise increments in DP to 180 mmHg. In the brachial vein, the diameter change in response to an increase in DP from 30 to 180 mmHg (distensibility) was reduced (P < 0.05) in the pressure-trained arm (11%) compared to that in the control arm before (23%) and after (21%) PT. The cephalic vein showed a similar response with a reduced (P < 0.05) distensibility in the pressure-trained arm (20%) compared to that in the control arm before (29%) and after (25%) PT. At any given DP, arm pain was less (P < 0.05) in the pressure-trained arm than in the control arm before and after PT, presumably reflecting the reduced venous distensibility in the pressure-trained arm. The results support the concept that the distensibility of venous walls adapts to meet the demands imposed by the prevailing local transmural pressures.

Pathogenesis of leukoaraiosis: Role of jugular venous reflux

Decreased Jugular Venous Distensibility in Migraine

Distensibility of Forearm Veins in Haemodialysis Patients on Duplex Ultrasound Testing Using Three Provocation Methods

The mechanisms of hemodynamic responses to orthostatic stresses and orthostatic stability (OS) of cosmonauts were studied before and after short-and long-term spaceflights (SFs) using orthostatic tests, as well as before, during, and after SFs using ultrasonic methods in tests with exposure to lower body negative pressure (LBNP). The capacitance and distensibility of the veins of the lower extremities were studied using occlusive air plethysmography before, during, and after SFs of different durations. A stay in microgravity has been proved to result in detraining of, mainly, the vascular mechanisms of compensating orthostatic perturbations. It has been established that the decrease in OS under the influence of microgravity is determined by a reduction of the vasoconstrictive ability of large blood vessels of the lower extremities; an increase in venous distensibility and capacitance of the legs; and an impairment of blood flow regulation, which leads to a cerebral blood flow deficit in orthostatic stresses, and of the initial individual OS before the flight. The results of preflight studies of hemodynamics by ultrasonic methods at LBNP and the data of orthostatic tests before SFs make it possible to predict the degree of decrease of OS after an SF proceeding in the normal mode. At the same time, the data of ultrasonic blood flow examination provide more a accurate estimation of OS and make it possible to assess the physiological reserves of hemodynamic regulation and to reveal the loss of regulation capacity even in cases where integrated indices (heart rate and blood pressure) are within the normal ranges.

The haemodynamic reaction to an acute emotional stress was tested in nine patients with essential and eleven with renal hypertension after an intravenous bolus of labetalol (0.6--1.6 mg/kg body-weight). Labetalol reduced the arteriolar tone at rest. The emotional blood pressure rise was maintained, but started from a lower level due to labetalol and under stress only rose to the pre-labetalol level. The diastolic pressure rose significantly less compared with control values, while systolic and mean blood pressure responses were not uniform. The usual emotional rise in heart rate and cardiac output was clearly diminished by labetalol. Total peripheral vascular resistance, which had been significantly reduced by labetalol, remained unchanged under acute emotional stress. In contrast to untreated hypertensives, venous distensibility and regional blood volume in the lower arm rose significantly on stress while on labetalol medication. Lower arm vascular resistance, which had also been reduced by labetalol, remained uninfluenced by stress: as a result, emotional hyperaemia was much less.

Objectives: Lower limb venous compliance is of hemodynamic importance for orthostatic challenge. The qualities of different venous compartments is however unknown. The aim was to study venous buffering compliance (vBC) as well as venous wall distensibility (vWD) in deep (femoral vein, FV) and superficial large veins (great saphenous vein, GSV), as well as to assess calf venous compliance (vC).Methods: Strain‐gauge plethysmography was used to assess vC. Diameter (D), vBC and vWD of the FV and GSV were examined with ultrasound in 15 young (YM, 25±1 yr) and 14 old (OM, 70±2 yr) males. D was measured at rest and after venous stasis (6 min, 60 mmHg), and vein area (A) calculated. Pressure‐Area curves (absolute, mm2, and relative, %) during a linear pressure decrease were produced, and vC, vBC and vWD calculated using a quadratic regression equation.Results: vC was greater in YM, P &lt; 0.05. vBC was greater in GSV in YM than OM, P &lt; 0.01. D was larger in FV than GSV in YM and OM, P &lt; 0.0001, and vBC was greater in FV than in GSV irrespective of age, P &lt; 0.01. However, when correcting for venous size (vWD), greater vWD was found in GSV than in FV in YM as well as OM, P &lt; 0.05.Conclusions: Calf venous compliance was greater in young as compared to old men. Femoral vein had higher venous buffering compliance than great saphenous vein, due to its greater size. When correcting for size, great saphenous vein showed greater wall distensibility than femoral vein.

Venous Reflux and Venous Distensibility in Varicose and Healthy Veins