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Ruben Dammers

Publications and source records attributed to Ruben Dammers.

14 recordsLinked to original sources
PubMed2005

Endothelin-1 levels and conduit artery mechanical properties in end-stage renal disease.

BACKGROUND: Endothelial cell (EC) dysfunction markers are increased in end-stage renal disease (ESRD). The present study focused on the relationship between EC markers, conduit artery wall mechanics and hemodynamics in ESRD. METHODS: In 29 ESRD patients and 16 controls, brachial artery diameter, distension, and wall thickness was measured and circumferential wall stress (CWS) calculated. Shear stress was determined with a shear rate-estimating system. Furthermore, von Willebrand factor antigen (vWF) and endothelin-1 (ET-1) levels were measured. RESULTS: vWF (p = 0.002) and ET-1 (p < 0.001) were higher in ESRD patients and vWF was related to ET-1 (r = 0.70, p = 0.005). Peak (p = 0.001) and mean shear stress (p = 0.003) were significantly lower in ESRD patients, and ET-1 showed an inverse log linear relation with both (peak: r = -0.59, p = 0.016; mean: r = -0.64, p = 0.007). Also, ET-1 was log linearly related to CWS (r = 0.58, p = 0.014). CONCLUSION: These results indicate that, in ESRD, conduit artery shear stress is lower, which might be secondary to an increased peripheral vascular resistance caused by higher ET-1 levels.

Aged↗
PubMed2005

The effect of flow changes on the arterial system proximal to an arteriovenous fistula for hemodialysis.

Arterial remodeling in response to flow changes is controlled by the endothelium, sensing wall shear stress (SS) changes. The present study focuses on the remodeling capacities of the brachial (BA) and radial artery (RA) of 16 renal failure patients after arteriovenous fistula creation. Pre- and postoperatively at predetermined time-points, diameter, wall thickness and peak and mean SS were assessed. After arteriovenous fistula creation, acute increases in BA SS (p = 0.018) and lumen diameter (p = 0.028) were observed. The diameter further increased in the next year (p = 0.023), whereas BA SS remained unchanged. RA SS and diameter increased acutely (p = 0.005) and remained unaltered after 1 y. RA wall thickness tended to decrease acutely (p = 0.059) and increased steadily during 1 y (p = 0.008). BA and RA diameter acutely increased after an acute SS rise and remained augmented after 1 y. Also, the RA vessel wall thickness enlarged, indicating structural remodeling. After 1 y, however, these changes did not result in SS restoration.

Aged↗
PubMed2003

Stenosis detection in forearm hemodialysis arteriovenous fistulae by multiphase contrast-enhanced magnetic resonance angiography: preliminary experience.

PURPOSE: To assess the feasibility and accuracy of multiphase contrast-enhanced magnetic resonance angiography (CE-MRA) in patients with dysfunctioning hemodialysis arteriovenous fistulae (AVF), using digital subtraction angiography (DSA) as the standard of reference. MATERIALS AND METHODS: Fifteen patients with dysfunctioning AVF (eight radiocephalic and seven graft AVF) underwent CE-MRA. Dysfunction was defined as a flow decline of more than 25% in 1 month measured by dilutional flow measurements. CE-MRA was performed during injection of 35 mL of gadolinium-DTPA. The CE-MRA sequence consisted of a time-resolved series of 10 scans, each lasting approximately 10 seconds. The technical parameters were TR/TE/FA/voxel = 5.4/1.6/40/3.1 mm(3), and a rectangular surface reception coil was used. All patients were scheduled to undergo DSA at which an intervention was carried out when a stenosis >or=50% was seen. Two observers, unaware of each other's findings and the findings at DSA, quantified the number and degree of stenosis in the failing AVF. Image quality for CE-MRA and DSA was scored on a 3-point scale. The diagnostic performance of CE-MRA was analyzed with receiver-operator characteristic (ROC) analysis. RESULTS: CE-MRA and DSA examinations were performed without side effects in all 15 patients. Image quality was scored significantly better on CE-MRA (observer 1: CE-MRA, 2.0; DSA, 1.3; P =.001; observer 2: CE-MRA, 2.0; DSA, 1.4; P =.002). Interobserver agreement for detection of >or=50% stenosis was 0.81 (95% confidence interval (CI) = 0.71-0.92) for CE-MRA and 0.69 (95% CI = 0.55-0.84) for DSA. ROC analysis revealed a mean area under the curve of 0.78. On the patient level, at the >or=50% threshold, mean sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100% (95% CI = 69%-100%), 10% (95% CI = 0%-78%), 70% (95% CI = 38%-92%), and 100% (95% CI = 50%-100%), respectively. At the >or=75% threshold, mean sensitivity, specificity, PPV, and NPV were 75% (95% CI = 20%-99%), 78% (95% CI = 39%-98%), 55% (95% CI = 12%-96%), and 89% (95% CI = 52%-100%), respectively. CONCLUSION: CE-MRA is a useful diagnostic tool for detecting stenoses in flow-declined hemodialysis AVF prior to interventional DSA.

Aged↗
PubMed2003

Evaluation of 4-mm to 7-mm versus 6-mm prosthetic brachial-antecubital forearm loop access for hemodialysis: results of a randomized multicenter clinical trial.

OBJECTIVE: Prosthetic arteriovenous fistulas for hemodialysis vascular access have a high incidence rate of thrombotic occlusions that result in graft failure. This randomized multicenter study was performed to assess the patency rates and the effect of 4-mm to 7-mm grafts on the development of stenoses. METHODS: A total of 109 patients who needed vascular access for hemodialysis were randomized to receive either 6-mm (n = 57) or 4-mm to 7-mm prosthetic brachial-antecubital forearm loop accesses (polytetrafluoroethylene). Duplex scanning, with measurement of blood flow and peak systolic velocity and detection of stenoses (>50%), was performed at 1, 6, and 12 months after surgery. Clinical data were obtained in a prospective manner and primary, assisted primary, and secondary patency rates were calculated with the Kaplan-Meier life-table analysis. Statistical analysis was performed with the independent samples t test and chi(2) test. RESULTS: At 1 year, patency rates were similar for both 4-mm to 7-mm and 6-mm prostheses (primary, 46% versus 43%; assisted primary, 62% versus 58%; secondary, 87% versus 91%). The incidence rate of thrombotic occlusion was comparable for both groups (0.74/patient-year versus 0.88/patient-year; P >.05). Mean graft flow at 1, 6, and 12 months was 1416 versus 1415 mL/min, 1345 versus 1319 mL/min, and 1595 versus 1265 mL/min (P >.05) for 4-mm to 7-mm and 6-mm grafts, respectively. Also, no differences in peak systolic velocities in any part of the grafts were observed. The percentage of stenoses detected was equal in both groups at 1 year after surgery (27% versus 20%; P >.05). CONCLUSION: A 4-mm to 7-mm tapered prosthetic brachial-antecubital forearm loop access did not reduce the incidence rates of stenoses and thrombotic occlusions compared with a 6-mm prosthetic conduit. Moreover, no differences in patency rates were observed. Therefore, we believe that the 4-mm to 7-mm graft should not be used routinely for hemodialysis vascular access.

Arteriovenous Shunt, Surgical↗
PubMed2003

Prospective evaluation of failure modes in autogenous radiocephalic wrist access for haemodialysis.

INTRODUCTION: Radiocephalic wrist arteriovenous fistulae (RCAVF) are the primary and best option for vascular access for haemodialysis treatment. However, 10-24% of these AVFs fail due directly to thrombosis and non-maturation. In a prospective study, the failure modes of radiocephalic AVFs and the impact of surgical and interventional treatment on fistula outcome were investigated. METHODS: The rate of thrombosis and non-maturation was evaluated in 43 RCAVFs. The selection of RCAVF creation was made on preoperatively determined duplex parameters. Fistula function was evaluated post-operatively by clinical examination and non-invasively measured AVF blood flow. A policy of a liberal use of radiological and/or surgical revision of non-functioning RCAVFs was made on the basis of duplex measured blood flow and angiographically detected vessel stenosis. RESULTS: Primary fistula function was achieved in 26 of 43 patients (60%). Non-maturation and thrombosis occurred in 14 (33%) and three (7%) patients, respectively. A total of 12 interventions (PTA 6; surgery 6) were needed, resulting in salvage of eight RCAVFs (47%). The blood flow in functioning AVFs was significantly higher compared to non-functioning AVFs at 1 (754 vs 440 cc/min), 7 (799 vs 524 cc/min) and 42 days (946 vs 532 cc/min) post-operatively. At the end, 34 RCAVFs (79%) became functional as vascular access for haemodialysis treatment. CONCLUSION: Primary RCAVFs have a high rate of failure. An aggressive approach towards early interventional treatment of these non-functional AVFs is worthwhile and leads to a considerable salvage rate. Early post-operative AVF flow measurement indicates the chance of successful maturation of RCAVF.

Aged↗
PubMed2003

Detection of cell-cycle regulators in failed arteriovenous fistulas for haemodialysis.

BACKGROUND: Chronic renal failure (CRF) patients rely on arteriovenous fistulas (AVFs) for haemodialysis vascular access. Intimal hyperplastic stenoses result in failure of AVFs and frequent intervention is required to maintain vascular access. The extent of intimal hyperplasia depends on the interplay between cyclins and cyclin-dependent kinases (e.g. cdk2), positively regulating cell-cycle progression. cdk activity is negatively modulated by the interaction with cdk inhibitory proteins, such as p21(Waf1) and p27(Kip1). Little is known about the expression of these proteins in the development of intimal hyperplasia in AVFs. METHODS: p21(Waf1), p27(Kip1), cdk2 and Proliferating Cell Nuclear Antigen immunoreactivity was determined in 18 failed AVFs from 16 CRF patients and 10 non-diseased vessels (five arteries and five veins). RESULTS: The percentage of p21(Waf1)-positive cells was significantly lower in AVFs (3+/-1%), compared with normal veins and arteries (62+/-4 and 63+/-4%, respectively; P<0.001). cdk2-positive cells were significantly higher in AVFs (40.7+/-3.7%) than in normal veins and arteries (2+/-1 and 0+/-0%, respectively; P<0.001). Although no difference in p27(Kip1) immunoreactivity was found between AVFs (37+/-17%) and veins (23+/-8%; P=0.208), it was lower in healthy arteries (17+/-11%; P=0.037). CONCLUSIONS: The data suggest that in failed AVFs, p21(Waf1), but not p27(Kip1), is related to intimal hyperplasia. This is the first report to show involvement of cell-cycle regulators in AVF-related human intimal hyperplasia.

Analysis of Variance↗
PubMed2003

Determinants of arterial distensibility in patients with renal failure.

BACKGROUND: An increased stiffness of the arterial system is an adverse risk factor for the outcome in patients with renal disease. Few studies have focused on the determinants of an increased arterial stiffness in patients with renal failure. As the percentage of patients with renal failure secondary to vascular disease and/or diabetes mellitus is rapidly growing, and the underlying disease per se may also influence the arterial wall properties, it may also be of interest to study the arterial wall properties in relation to the etiology of kidney disease. METHODS: The distensibility coefficient (DC) of the common carotid artery was used as a marker of arterial stiffness. One hundred and seventeen patients were studied: 47 patients (aged 63 +/- 10 years) with renal failure secondary to vascular disease and/or diabetes mellitus and 70 patients (aged 57 +/- 13 years) with other diagnoses. The origin of the renal failure was retrieved from the patients' charts. RESULTS: Age, mean arterial pressure, and serum calcium level were each independent predictors of arterial stiffness (DC). The DC was significantly lower in the patients with vascular renal disease or diabetes mellitus [11.0 +/- 5.5 (1/MPa)] as compared with patients with renal/urological diseases [15.4 +/- 7.5 (1/MPa)]. Nevertheless, after correction for potentially confounding variables, the relation between cause of renal disease and DC lost significance in the overall group, but remained significant (p < 0.05) in the younger age groups (</=61 years; median age of the patient group). CONCLUSIONS: Age, mean arterial pressure, and serum calcium level were independent predictors of arterial stiffness in our patients with renal failure. Only in younger dialysis patients, the origin of renal failure was an independent predictor of arterial wall stiffness.

Cohort Studies↗
PubMed2002

Shear stress depends on vascular territory: comparison between common carotid and brachial artery.

Shear stress (SS) is thought to be constant throughout the vascular system. Evidence for this supposition is scarce, however. To verify this hypothesis in vivo, we assessed common carotid (CCA) and brachial artery (BA) peak and mean wall shear rate (SR) noninvasively in 10 healthy volunteers (23.7 +/- 3.4 yr) with an ultrasound SR estimation system. SS was estimated from SR and calculated whole blood viscosity. SR was higher (P < 0.05) in the CCA (mean: 359 +/- 111 s(-1); peak: 1,047 +/- 345 s(-1)) than in the BA (mean: 95 +/- 24 s(-1); peak: 770 +/- 170 s(-1)). Whole blood viscosity was higher in the BA than in the CCA (5.1 +/- 0.7 vs. 3.3 +/- 0.6 mPa. s; P < 0.001). Peak SS did not differ between the CCA and the BA, whereas mean SS was significantly higher in the CCA (1.15 +/- 0.21 Pa) than in the BA (0.48 +/- 0.15 Pa; P < 0.001). These results demonstrate that BA SS strongly deviates from CCA SS in vivo.

Adult↗
PubMed2002

Brachial artery shear stress is independent of gender or age and does not modify vessel wall mechanical properties.

The objective of the present study was to obtain brachial artery (BA) baseline shear stress (SS) values in healthy volunteers and to relate this to gender and age. Peak and mean wall shear rate (SR) were noninvasively measured in 30 healthy subjects using an SR estimation system. Arterial diameter and wall characteristics were obtained with a wall tracking system. SS was estimated from SR and calculated whole blood viscosity. Intrasubject variability and the effects of age and gender were assessed. Intrasubject variability of BA peak and mean SR were 16.2% and 28.6%. Baseline peak ( approximately 3.0 +/- 0.7 Pa) and mean SS ( approximately 0.5 +/- 0.2 Pa) were not gender-dependent, nor were they influenced by age. No vessel wall parameter related to BA SS. No differences in BA SS were observed between the genders and no influence of age was apparent. Our results indicate that the BA adequately responds to chronic changes in blood flow.

Adult↗
PubMed2002

Arterial wall properties in patients with renal failure.

Hemodialysis (HD) patients commonly show abnormalities of the arterial system. Only a few studies have focused on arterial wall properties in patients with early stages of renal insufficiency and patients on peritoneal dialysis (PD) therapy. In this study, the distensibility coefficient (DC), a marker of arterial stiffening and intima media thickness (IMT) of the common carotid artery (CCA) and a surrogate marker of atherosclerosis, was assessed in four age-matched groups of patients: 18 HD patients, 36 PD patients, 30 patients with chronic renal failure (CRF) not yet on dialysis therapy with a creatinine clearance (CCl) between 10 and 70 mL/min, and 25 normotensive controls with normal renal function. Arterial wall properties were assessed by an automated vessel wall detection system. In patients with CRF and HD patients, but not PD patients, the DC of the CCA was significantly reduced (P < 0.05) compared with controls (CRF, 12.6 +/- 7.5 10(-3)/kPa; HD, 11.6 +/- 7.6 10(-3)/kPa; and PD, 14.7 +/- 6.2 10(-3)/kPa compared with controls, 16.7 +/- 4.6 10(-3)/kPa). In patients with CRF, a significant relationship was found between CCl and the DC (r = 0.41; P = 0.02). IMT was not different among patients with CRF (589 +/- 115 microm), HD (622 +/- 115 microm) and PD patients (585 +/- 121 microm), and controls (668 +/- 150 microm). In conclusion, compared with controls, the DC of the CCA was significantly reduced in HD patients and those with CRF, but not PD patients. In patients with CRF, the DC correlated significantly with CCl. IMT did not differ between groups of renal patients and controls.

Arteriosclerosis↗
PubMedDate not supplied

Lumbar disc herniation: level increases with age.

BACKGROUND: Prompted by the clinical impression that L4 radicular syndrome and disc herniations at L3-4 occurred at older ages we studied the correlation between age and level of herniated discs. METHODS: We retrospectively correlated mean age and level of disc herniation of patients suffering from lumbar disc herniation. Data from 1431 patients were obtained from the neurologic database of the Atrium Medical Center Heerlen from 1995 through 1998. Nonparametric data were analyzed with the Mann-Whitney U test, and correlation was analyzed using linear regression. RESULTS: Mean ages of the patients with disc herniation at L5-S1, L4-5, L3-4, and L2-3 were 44.1 +/- 0.5 years, 49.5 +/- 0.6 years, 59.5 +/- 0.9 years, and 59.6 +/- 2.7 years, respectively. Mean ages were significantly higher with herniation levels at L4-5, L3-4, and L2-3 compared to L5-S1 (p < 0.0001). Analogously, the mean age of patients with disc herniation at L3-4 was significantly higher compared to those with herniation at L4-5 (p < 0.0001). No difference in mean age was seen between L3-4 and L2-3 (p = 0.815). A strong correlation was observed between the level of herniation and increasing age (R = 0.371; p < 0.0001). CONCLUSION: These results indeed prove that with increasing age, lumbar disc herniation is more cranially localized. It may help in understanding the patho-anatomic process of disc herniation, and in recognizing higher level radicular syndromes in advanced age.

Adolescent↗
PubMedDate not supplied

Fluid status, blood pressure, and cardiovascular abnormalities in patients on peritoneal dialysis.

OBJECTIVE: Hypertension, reduced arterial distensibility, and left ventricular hypertrophy (LVH) are risk factors for mortality in hemodialysis patients. However, few studies have focused on the relation between fluid status, blood pressure (BP), and cardiovascular abnormalities in peritoneal dialysis (PD) patients. This study was designed, first, to assess, using tracer dilution techniques, fluid status in PD patients compared to a control population of stable renal transplant (RTx) patients; second, to study the relation between fluid status, BP, and arterial wall abnormalities; third, to assess the determinants of cardiac structure; and last, to compare office and ambulatory BP measurements with respect to cardiac abnormalities. DESIGN: Cross-sectional study. SETTING: Multicenter study. PATIENTS: 41 stable PD patients with a mean Kt/V urea of 2.4 +/- 0.7, and 77 stable RTx patients. INTERVENTION: Fluid status was assessed by tracer dilution techniques: extracellular volume (ECV) with bromide dilution; total body water (TBW) with deuterium oxide; and plasma volume (PV) with dextran 70. Echocardiography was performed to assess left ventricular mass (LVM), left ventricular end diastolic diameter (LVEDD), and relative wall thickness as indicators of LVH. Echography of the common carotid artery was performed to assess arterial distensibility. Both office and 24-hour ambulatory BP measurements were performed. RESULTS: Fluid status, as assessed by ECV corrected for body surface area (BSA) (ECV:BSA), was significantly different between PD and RTx patients (9.4 +/- 2.6 vs 8.6 +/- 1.2 L/m2, p < 0.05). In 36.6% of the PD patients, ECV:BSA was above the 90th percentile of the RTx patients. Fluid status corrected for BSA, assessed by TBW (TBW:BSA), ECV (ECV:BSA), or plasma volume (PV:BSA), was significantly related to diastolic BP (DBP) (r = 0.35, r = 0.37, r = 0.53; p < 0.05). Arterial distensibility of the common carotid artery was related to systolic BP (SBP) (r = -0.36, p < 0.05). ECV was significantly related to LVEDD (r = 0.41, p < 0.05) as a marker of eccentric LVH, whereas arterial distensibility was related to relative wall thickness (r = -0.53, p < 0.001) as a marker of concentric LVH. An abnormal day-night BP rhythm, which was not related to fluid status, was observed in 68.4% of patients. Ambulatory DBP and SBP but not office DBP and SBP were related to LVM (r = 0.43, r = 0.46; p < 0.01). CONCLUSIONS: A large proportion of PD patients whose treatment prescriptions are in accordance with the Dialysis Outcomes Quality Initiative guidelines were found to be overhydrated compared with a population of stable RTx patients. Fluid status was significantly related to DBP and eccentric LVH, whereas arterial distensibility of the common carotid artery was significantly related to SBP and concentric LVH. In contrast to ambulatory BP, office BP was not related to LVM.

Adult↗