Cancer-related fatigue in patients before and after radical prostatectomy. Results of a prospective multi-centre study.

PURPOSE: A multi-centre, longitudinal study was conducted to assess the prevalence of fatigue amongst men with localized prostate cancer, to describe several dimensions of fatigue and to explore the predictability of fatigue by psychological distress and physical function. METHODS: The prevalence of fatigue was evaluated using the Multidimensional Fatigue Inventory in 329 prostate cancer patients before, 3, 6 and 12 months after surgery. Psychological distress was assessed using the Hospital Anxiety and Depression Scale. Physical function was measured using the EORTC QLQ-C30. RESULTS: After surgery, about 14 % of the patients were screened with chronic fatigue. For all dimensions of fatigue, only small longitudinal changes could be observed. Psychological distress could be identified as a good predictor of fatigue after but not before surgery. CONCLUSIONS: Radical prostatectomy has no or little impact on the prevalence of fatigue. However, about 14 % of patients with chronic fatigue could possibly benefit from psychosomatic interventions. Interventions should consider the simultaneous appearance of fatigue and psychological distress and a reduced physical function.

[The assessment of therapy success after radical prostatectomy]. / Die Beurteilung des Behandlungserfolges nach Radikaler Prostatektomie.

OBJECTIVES: Patient satisfaction plays an important role in the outcome quality of treatment for localized prostate carcinoma. This paper identifies factors that impact patients' assessment of therapy success one year after surgery. METHODS: Patient assessment of therapy success was measured with the Hamburger Fragebogen zum Krankenhausaufenthalt (Lecher et al. 2002). Also, several sociodemographic, clinical and quality-of-life factors were tested for their impact on the patient assessment of therapy success. RESULTS: 25 % of patients gave a negative assessment of therapy success. Factors with the strongest impact were urinary incontinence, sexual impotence, younger age and higher risk of recidive. CONCLUSIONS: Especially the prevention of urinary continence and sexual dysfunction may lead to a better assessment of therapy. Moreover, the patients' expectations have a great impact on the assessment of therapy success.

Treatment of perigraft seroma in expanded polytetrafluoroethylene grafts by sequential fibrin sealing of the outer graft surface.

BACKGROUND: The recommended standard for treatment of perigraft seroma (PS) is the graft removal and the reconstruction using an alternative prosthesis. We assumed that a fibrin sealing of the outer surface of expanded polytetrafluoroethylene (ePTFE) grafts would prevent leakage and used this technique in the treatment and prevention of PS. METHODS: Over a 10-year period, 24 patients were treated for PS after subcutaneous implantation of ePTFE grafts (14 arterial bypasses and 10 arteriovenous grafts). Affected graft segments were temporarily removed and underwent sequential fibrin sealing technique before reimplantation. In addition, an in vitro experiment was carried out to demonstrate the efficacy of fibrin sealing to prevent leakage through the ePTFE graft wall, after its hydrophobic barrier was destroyed by filling with saline solution under pressure. RESULTS: A cure of PS was observed in 20 patients (84%) at a follow-up period of 37 ± 18 months. A later graft infection was not seen in any patient. The patency rate of reconstructed grafts appears to be unaffected. In the performed experiment we have demonstrated an elimination of leakage through the graft wall by the fibrin sealing technique. CONCLUSIONS: Sequential fibrin sealing of the outer surface is an effective way to treat PS in ePTFE grafts. However, failure of this treatment cannot be precluded. Further studies are necessary that may provide further insights into the causes and best treatment of PS and the possibly important role of PS in the aneurysm enlargement after complete endovascular exclusion with ePTFE endografts.

Real-world experience with cabazitaxel in patients with metastatic castration-resistant prostate cancer: a final, pooled analysis of the compassionate use programme and early access programme.

BACKGROUND: Cabazitaxel is a second-generation taxane approved for use in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with docetaxel. Early access programmes were established to allow eligible patients with mCRPC access to cabazitaxel before regulatory approval. MATERIALS AND METHODS: The primary objective was to allow access to cabazitaxel before commercial availability for patients with mCRPC whose disease had progressed during or after chemotherapy with docetaxel; the secondary objective was overall safety. Patients received cabazitaxel 25 mg/m2 on Day 1 of a 21-day cycle, with daily oral 10 mg prednisone/prednisolone. G-CSF was administered per ASCO guidelines. RESULTS: In total, 1432 patients received cabazitaxel across 41 countries between 2010 and 2014 (median 6.0 treatment cycles [range 1-49]). The most frequently occurring treatment-emergent adverse events (TEAEs) possibly related to treatment were diarrhoea (33.3%), fatigue (25.4%) and anaemia (23.7%); the most frequently occurring possibly related Grade 3/4 TEAEs were neutropenia (18.7%) and febrile neutropenia (6.9%). G-CSF was administered in ≥ 1 cycle in 64% of patients (10.1% therapeutic use; 57.8% prophylactic use; 9.7% both uses). CONCLUSION: The safety profile of cabazitaxel in this pooled analysis of two cabazitaxel early access programmes was manageable and consistent with previous Phase III trials (TROPIC, PROSELICA).

Experimental study of hemodynamics in procedures to treat access-related ischemia.

OBJECTIVE: This experimental study investigated the hemodynamic effect of corrective procedures for arteriovenous access-related ischemia in pulsatile flow. METHODS: Silicone models of an emulated tapered and bifurcated arterial tree of the upper arm and forearm were integrated into a pulsatile flow circuit. The model allowed the study of hemodynamics of simulated arteriovenous fistulas, including collateral circulation, as well as the study of different simulated procedures to improve distal hypoperfusion. Flow rates and arterial pressure were measured simultaneously during simulation of corrective procedures and correlated to hemodynamic values of uncorrected ischemia. RESULTS: It was demonstrated that the more proximally localized an arteriovenous anastomosis is, the higher the distal arterial pressure will be at any given fistula flow. Reduction of the fistula flow resulted in a significant improvement of distal perfusion. Ligation of the artery distal to the arteriovenous fistula to prevent retrograde flow increased the distal perfusion only slightly in simulated ischemia. In contrast, the simulated corrective procedures of distal revascularization interval ligation and proximalization of arterial inflow resulted in a significant improvement. The most significant improvement of distal perfusion was observed with the simulated proximalization technique, whereas the effect of distal revascularization technique was less pronounced at higher fistula flow. Arterial ligation after distal revascularization increased the distal pressure only by 10%. CONCLUSION: A more centrally localized arteriovenous anastomosis and a reduction of fistula flow significantly increase distal perfusion. The procedure of proximalization of arterial inflow is at least equivalent to the distal revascularization interval ligation technique for the correction of distal ischemia, but does not sacrifice a patent axial artery. The moderate effect of interval ligation of the latter technique should be evaluated by further intraoperative measurements.

Dacron vs. PTFE as bypass materials in peripheral vascular surgery--systematic review and meta-analysis.

BACKGROUND: In peripheral vascular bypass surgery different synthetic materials are available for bypass grafting. It is unclear which of the two commonly used materials, polytetrafluoroethylene (PTFE) or polyester (Dacron(R)) grafts, is to be preferred. Thus, the aim of this meta-analysis and systematic review was to compare the effectiveness of these two prosthetic bypass materials (Dacron and PTFE). METHODS: We performed a systematic literature search in MEDLINE, Cochrane-Library - CENTRAL, EMBASE and other databases for relevant publications in English and German published between 1999 and 2008. Only randomized controlled trials were considered for inclusion. We assessed the methodological quality by means of standardized checklists. Primary patency was used as the main endpoint. Random-effect meta-analysis as well as pooling data in life table format was performed to combine study results. RESULTS: Nine randomized controlled trials (RCT) were included. Two trials showed statistically significant differences in primary patency, one favouring Dacron and one favouring PTFE grafts, while 7 trials did not show statistically significant differences between the two materials. Meta-analysis on the comparison of PTFE vs. Dacron grafts yielded no differences with regard to primary patency rates (hazard ratio 1.04 (95% confidence interval [0.85;1.28]), no significant heterogeneity (p = 0.32, I2 = 14%)). Similarly, there were no significant differences with regard to secondary patency rates. CONCLUSION: Systematic evaluation and meta-analysis of randomized controlled trials comparing Dacron and PTFE as bypass materials for peripheral vascular surgery showed no evidence of an advantage of one synthetic material over the other.

Modulatory role of food, feeding regime and physical exercise on body weight and insulin resistance.

Energy intake and expenditure is a highly conserved and well-controlled system with a bias toward energy intake. In times of abundant food supply, individuals tend to overeat and in consequence to increase body weight, sometimes to the point of clinical obesity. Obesity is a disease that is not only characterized by enormous body weight but also by rising morbidity for diabetes type II and cardiovascular complications. To better understand the critical factors contributing to obesity we performed the present study in which the effects of energy expenditure and energy intake were examined with respect to body weight, localization of fat and insulin resistance in normal Wistar rats. It was found that a diet rich in fat and carbohydrates similar to "fast food" (cafeteria diet) has pronounced implication in the development of obesity, leading to significant body weight gain, fat deposition and also insulin resistance. Furthermore, an irregularly presented cafeteria diet (yoyo diet) has similar effects on body weight and fat deposition. However, these rats were not resistant to insulin, but showed an increased insulin secretion in response to glucose. When rats were fed with a specified high fat/carbohydrate diet (10% fat, 56.7% carbohydrate) ad lib or at the beginning of their activity phase they were able to detect the energy content of the food and compensate this by a lower intake. They, however, failed to compensate when food was given in the resting phase and gained more body weight as controls. Exercise, even of short duration, was able to keep rats on lower body weight and reduced fat deposition. Thus, inappropriate food intake with different levels of energy content is able to induce obesity in normal rats with additional metabolic changes that can be also observed in humans.

Cabazitaxel plus prednisone for metastatic castration-resistant prostate cancer progressing after docetaxel: results from the German compassionate-use programme.

BACKGROUND: Cabazitaxel (Cbz) is an approved second-line treatment in metastatic castration-resistant prostate cancer (mCRPC) following docetaxel therapy with a significant survival benefit compared with mitoxantrone. However, grade 3/4 toxicities were reported in 82% of patients. OBJECTIVE: To report on the safety results of mCRPC patients treated within a compassionate-use programme in Germany. DESIGN, SETTING, AND PARTICIPANTS: A total of 111 patients with a mean age of 67.9 yr (range: 49-81 yr) and progressive mCRPC were included. Patients had received a mean number of 12.7 ± 10.8 cycles (range: 6-69 cycles) of docetaxel with a mean cumulative dose of 970.9 mg/m(2); mean time from last docetaxel application to progression was 6.95 mo (range: 2-54 mo). Of the patients, 31.5% progressed by prostate-specific antigen (PSA) increase only; the remainder had a combination of PSA increase and clinical progression. INTERVENTION: Cbz at a dosage of 25mg/m(2) intravenously every 3 wk combined with 5mg of oral prednisone twice a day. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Treatment-associated toxicity was the primary study end point; progression-free and overall survival were secondary end points. A descriptive statistical analysis was performed. RESULTS AND LIMITATIONS: Patients received a mean number of 6.5 ± 2.2 cycles of Cbz and a mean cumulative dose of 160.3 ± 51.5mg/m(2). Grade 3 and 4 treatment-emergent adverse events were recorded in 34 patients (30.6%) and 18 patients (16.2%), respectively. Grade 3/4 anaemia, neutropenia, and thrombocytopenia were reported in 4.5%, 7.2%, and 0.9% of the patients, respectively. Neutropenic fever was reported in 1.8% of the patients. Grade 3/4 gastrointestinal toxicity was identified in 4.5% of the patients. Three patients died because of Cbz-related toxicity. Granulocyte colony-stimulating growth factors were used in 17.1% of patients. The limitations are due to the nonrandomised nature of the trial. CONCLUSIONS: Treatment with Cbz is tolerable and is associated with a low incidence of serious adverse events in a real-world patient population with CRPC. The outcome of serious adverse events can be minimised with proactive treatment management and conscientious monitoring.

Early continence in patients with localized prostate cancer. A comparison between open retropubic (RRPE) and endoscopic extraperitoneal radical prostatectomy (EERPE).

OBJECTIVE: The study examined and compared continence rates in prostate cancer patients who had undergone either open retropubic prostatectomy (RRPE) or endoscopic extraperitoneal radical prostatectomy (EERPE). The core question was whether the surgical approach had an effect on the patients' continence status 3 months after surgery. METHODS: We conducted a multicentric, longitudinal study in 7 German hospitals. Three hundred fifty prostate cancer patients (166 EERPE, 184 RRPE) were asked to self-assess symptoms associated with urinary incontinence (UI) 1 day before and 3 months after prostatectomy. Symptoms of UI were assessed using the EORTC QLQ-PR25 questionnaire. Urinary continence was defined according to (1) the use of no protective pad, (2) the use of up to a single protective pad in a 24-hour period, and (3) according to the patient's self-assessment. A binary regression model was employed to predict early continence status. RESULTS: Three months after prostatectomy, 44% of patients who underwent EERPE and 40% of patients who underwent RRPE were completely continent. Patients who underwent nerve-sparing prostatectomy and patients younger than 65 years had a better chance of regaining urinary continence earlier. The surgical approach had no significant impact on the patients' continence status. Limitations of the study are a drop-out rate of 39% and sociodemographic and clinical differences between both treatment groups. CONCLUSIONS: Three months after prostatectomy, there were no significant differences between both treatment groups regarding urinary continence. The surgical approach had no significant effect on the patients' continence status. Higher age and non-nerve-sparing surgery are associated with a longer period of convalescence.

Transition from atherosclerosis to aortic aneurysm in humans coincides with an increased expression of RAS components.

While the renin-angiotensin system (RAS) is widely recognized to be involved in atherosclerosis, its potential role in the progression from atherosclerotic lesions to abdominal aortic aneurysm (AAA) is poorly understood. The present study aimed to investigate which components of the RAS may render the atherosclerotic aorta aneurysmatic. The expression of renin, prorenin/renin receptor, angiotensinogen, AT1- and AT2 receptors, cathepsin D, cathepsin G and chymase was examined by immunoblotting and immunohistochemistry in human atherosclerotic, aneurysmatic and healthy aortic tissues obtained from patients undergoing elective repair or at autopsy. AT1- and AT2 receptor mRNA expression was determined using quantitative real-time RT-PCR. All investigated local RAS components were up-regulated in atherosclerotic as compared to healthy tissues. AAA compared to atherosclerosis was characterized by a further increase in the expression of all RAS components except for the AT2 receptor. Cathepsin D was exclusively up-regulated in AAA. Most RAS components co-localized with infiltrating leukocytes or mast cells pointing to their contribution to inflammatory processes. Due to their proteolytic features, some RAS components (cathepsin D and cathepsin G and chymase) may contribute to AAA formation by accessory mechanisms. Taken together, our data suggest that in humans, RAS activation is not just a key-player in the pathogenesis of atherosclerosis, but that a further increasing activation may be involved in the transition from atherosclerosis to AAA.

Organ-sparing treatment of advanced bladder cancer: paclitaxel as a radiosensitizer.

BACKGROUND AND PURPOSE: Transurethral resection of bladder tumor (TUR-BT) and radiochemotherapy with cisplatin achieve high rates of bladder preservation and survival figures identical to radical cystectomy in muscle-invasive bladder cancers. The authors have investigated the potential use of paclitaxel in a radiochemotherapy protocol for patients with inoperable bladder carcinomas and mainly contraindications to cisplatin. PATIENTS AND METHODS: Between October 1997 to August 2004, 42 patients (median age 71 years) suffering from muscle-invasive (n=32) or recurrent (n=10) bladder cancers were treated with a paclitaxel-containing radiochemotherapy (paclitaxel 25-35 mg/m(2) twice weekly) after TUR-BT (R0/1/2/x in n=18/4/14/3) or cystectomy with residual tumor (n=3). Five patients received additional cisplatin. Radiation treatment was administered to a total dose of 45-60 Gy. RESULTS: 76.2% completed the planned regimen. Adaptations of treatment were mainly required due to diarrhea. Grade 3/4 toxicities occurred in 15/1 patients. Severe renal toxicities did not occur. 28 patients underwent restaging TUR-BT 6 weeks after radiochemotherapy (complete remission/partial remission/progressive disease: n=24/3/1). Three patients developed a local recurrence and four distant metastases. Seven patients died from tumor, six of other reasons. CONCLUSION: Radiochemotherapy with paclitaxel was feasible and this bladder approach needs further investigation to evaluate whether paclitaxel could become a substitute for cisplatin.

Proximalization of the arterial inflow: a new technique to treat access-related ischemia.

OBJECTIVE: Arteriovenous access-related ischemia is an uncommon but serious and occasionally devastating complication. Distal revascularization-interval ligation (DRIL) has been established as a standard treatment procedure; however, an axial artery is ligated and the distal perfusion is maintained by the construction of an arterial bypass. Because such an approach, in principle, appears undesirable, we developed and applied an alternative technique referred to as proximalization of the arterial inflow (PAI). This procedure converts the arterial supply of the arteriovenous access to a more proximal artery with higher capacity by using a small-caliber polytetrafluoroethylene graft as a feeder. METHODS: From January 1999 to June 2005, the PAI technique was applied in 30 patients. The indication was seen in patients with severe distal ischemia who had a flow volume rate of <800 mL/min in a native fistula and <1000 mL/min in prosthetic access. RESULTS: Pain was the dominant symptom of ischemia in most patients before surgery. In 37%, a tissue loss was observed. The symptoms of access-related ischemia disappeared completely in 84% of patients and improved significantly in 16%. The significant hemodynamic improvement was confirmed by an increase of the intraoperatively measured mean distal arterial pressure from 32 +/- 9 mm Hg to 63 +/- 8 mm Hg. The digital-brachial index increased from 0.40 +/- 0.10 to 0.83 +/- 0.07. The mean access flow rate was 658 +/- 80 mL/min after PAI and did not differ significantly with the preoperative value (634 +/- 181 mL/min). With a mean follow-up interval of 26.1 +/-19.1 months, the primary and secondary patency rates were, respectively, 87% and 90% at 1 year and 67% and 78% at 3 years. CONCLUSIONS: The PAI procedure represents a well-suited alternative to the DRIL technique for the treatment of patients who develop ischemia after creation of an arteriovenous access. Results for access salvage and disappearance of ischemic symptoms are equivalent to the DRIL technique. In contrast to the DRIL procedure, the PAI technique preserves the natural arterial pathway. Hence, PAI is preferable for surgeons who are reluctant to ligate an axial artery and are concerned about potentially disastrous consequences.

Flow reduction in high-flow arteriovenous access using intraoperative flow monitoring.

PURPOSE: This study used intraoperative monitoring of the access flow to evaluate the results of flow reduction in the management of high-flow arteriovenous access-related symptoms of distal ischemia and cardiac insufficiency. METHODS: A retrospective study was conducted of 95 patients (78 with ischemia, 17 with cardiac failure) who underwent flow reduction between 1999 and 2005. A preoperatively measured access flow-volume rate > 800 mL/min for autogenous accesses (n = 77) and > 1200 mL/min for prosthetic accesses (n = 18) was the selection criterion for the use of a flow reduction procedure. Flow reduction was achieved using a spindle-like narrowing suture near the anastomosis and final placement of a polytetrafluoroethylene strip while a flow meter was used for intraoperatively measuring the access flow. The desired postoperative flow was 400 mL/min for autogenous and 600 mL/min for prosthetic accesses. RESULTS: The mean preoperative access flow was 1469 +/- 633 mL/min in patients with ischemia and 2084 +/- 463 mL/min in patients with cardiac failure, without significant differences between access types. The flow was reduced to 499 +/- 175 mL/min for autogenous accesses and to 676 +/- 47 mL/min for prosthetic accesses. The mean follow-up was 25 months (range, 1 to 73 months). Complete long-term relief of symptoms was observed in 86% of patients with ischemia and in 96% of patients with cardiac failure. Reconstruction significantly increased the digital-brachial index (0.41 +/- 0.12 vs 0.74 +/- 0.11; P < .05) and mean distal arterial pressure (47 +/- 17 mm Hg vs 79 +/- 21 mm Hg; P < .05) in patients with ischemia. Primary patency rates were significantly better for reconstructed autogenous accesses compared with rates of prosthetic accesses (91% +/- 4% vs 58% +/- 12% at 12 months; 81% +/- 6% vs 41% +/- 14% at 36 months; P < .001). The low patency of reconstructed prosthetic accesses is due to the high thrombosis risk of accesses that have a flow < 700 mL/min. CONCLUSIONS: Flow reduction using intraoperative access flow monitoring is an effective and durable technique allowing for the correction of distal ischemia and cardiac insufficiency in patients with a high-flow autogenous access. The desired postoperative access flow of 400 mL/min is not associated with an increased risk of thrombosis. Flow reduction of prosthetic access is as effective; however, a higher access flow than the desired 600 mL/min seems to be necessary to achieve an acceptable patency in prosthetic accesses.

Arterioarterial prosthetic loop: a new approach for hemodialysis access.

OBJECTIVES: In this report we present a novel procedure that uses an arterioarterial prosthetic loop (AAPL) with the proximal axillary or the femoral artery as a vascular access for hemodialysis in patients who have inadequate vascular conditions for creating an arteriovenous fistula or graft. METHODS: Between April 1996 and September 2004, 34 patients received 36 AAPLs as vascular access, either as an axillary chest loop (n = 31) or as a femoral loop (n = 5). In this procedure the artery is ligated between the anastomoses to direct flow through the AAPL. Data from all patients undergoing the procedure were prospectively collected. RESULTS: The indication for an AAPL was the unsuitability of large deep veins in 64%, steal syndrome in 11%, the combination of only a suitable femoral vein and severe peripheral arterial disease in 22%, and congestive heart failure in 3%. All AAPLs were cannulated 18 +/- 4 days postoperatively. Mean follow-up was 31 months (range, 1 to 83). Primary patency was 73% and secondary patency was 96% at 1 year; these rates at 3 years were 54% and 87%, respectively. The rate of all interventions for the maintenance of AAPL function was 0.47 procedures per patient year. Four grafts were abandoned. More than 11,000 hemodialyses with proven efficiency were performed. CONCLUSIONS: The AAPL is an unusual but useful and easy-to-perform alternative procedure to create vascular access for hemodialysis. It can provide survival for strictly selected patients in whom conventional vascular access is not possible. The axillary chest AAPL is preferred.

Organ-sparing treatment in muscle-invasive bladder cancer.

BACKGROUND AND PURPOSE: Organ-sparing treatment of bladder cancer by a trimodality approach is feasible and effective. In this study, the results of a series of patients are reported, who were, in the majority, not suitable for major surgery. PATIENTS AND METHODS: In the period from June 1995 through December 2003, 68 patients (64 males, four females) with urothelial bladder cancer were treated with curative intent. The median age was 68 years (range 42-82 years). Clinical T-category was 32x T2, 20x T3, and 16x T4. Transurethral resection was performed in all cases, and a complete TUR-BT (transurethral resection of bladder tumor) was attempted, if possible. Radiotherapy was administered in conventional fractionation (five fractions of 1.8 Gy per week) up to 50.4 Gy to bladder, and regional nodes and the whole bladder received a boost up to 54-59.4 Gy. 34 patients received concurrent cisplatin-based chemotherapy (25 mg/m(2) on days 1-5 and 29-33), and patients with impaired renal function were either treated with irradiation alone (n = 7) or received paclitaxel as alternative to cisplatin in a phase II protocol or on an individual decision (n = 27). The median follow-up was 34 months (range 2-104 months). RESULTS: A histologically confirmed complete remission (CR) on restaging cystoscopy was observed in 40/46 patients (87%) who underwent restaging cystoscopy. CR rates were not significantly correlated to T-category (CR: 24/32 T2, 9/19 T3, and 9/16 T4 tumors) or clinical nodal status. Patients with non-radical resection and macroscopic residual tumor (R2 resection) achieved a CR in only 39% (12/31); this figure was significantly lower as compared to patients with radical R0 TUR-BT (CR: 15/16, 94%, p = 0.013) Furthermore, age and preexisting anemia had no impact on response. The overall survival of the whole group was 45% after 5 years, and survival according to clinical T-category was 62% for T2, 43% for T3, and 19% for T4 (p = 0.015). In eleven patients, local disease progression or relapse was observed. So far, only one salvage cystectomy has been performed, due to contraindications to surgery in the majority of patients. CONCLUSION: The data obtained in this study confirm the high efficacy of TUR and radiochemotherapy for locally advanced bladder cancer.

Computational fluid dynamics and vascular access.

Anastomotic intimal hyperplasia caused by unphysiological hemodynamics is generally accepted as a reason for dialysis access graft occlusion. Optimizing the venous anastomosis can improve the patency rate of arteriovenous grafts. The purpose of this study was to examine, evaluate, and characterize the local hemodynamics and, in particular, the wall shear stresses in conventional venous end-to-side anastomosis and in patch form anastomosis (Venaflo) by three-dimensional computational fluid dynamics (CFD). We investigated the conventional form of end-to-side anastomosis and a new patch form by numerical simulation of blood flow. The numerical simulation was done with a finite volume-based algorithm. The anastomotic forms were constructed with usual size and fixed walls. Subdividing the flow domain into multiple control volumes solved the fundamental equations. The boundary conditions were identical for both forms. The velocity profile of the patch form is better than that for the conventional form. The region of high static pressure caused by flow stagnation is reduced on the vein floor. The anastomotic wall shear stress is decreased. The results of this study strongly support patch form use to reduce the incidence of intimal hyperplasia and venous anastomotic stenoses.

Effect of tapered grafts on hemodynamics and flow rate in dialysis access grafts.

AIM: Aside from the high incidence of venous stenosis, high-output failure and peripheral steal syndromes remain serious problems of vascular access. Meanwhile commercial tapered grafts are available to address this topic, but little is known about its effect neither on graft flow nor on hemodynamics. METHODS: Anastomotic models were constructed using a clear silicon elastomer. The arterial anastomosis was shaped in two ways: 1) like a direct connection of artery and 7-mm graft and 2) with a 4-mm diameter segment between artery and graft. Hemodynamic measurements were performed in a pulsatile flow circuit to simulate blood flow at physiological conditions. Flow patterns were obtained by direct dye injection. Additionally, the correlation between the length of narrow segment and mean arterial pressure was investigated. RESULTS: In all models using a 4-mm segment, the oscillating anastomotic vortex was disappeared. This vortex was shifted to the area behind the well-rounded expansions of the graft demonstrating a new separation region, but the flow direction was constant during the whole simulated cycle. At identical pressure rates and waveforms the length of narrow segment determined the graft flow rate directly (e.g., at mean pressure 100 mmHg, flow reduction up to 28% in 4-mm segments, and up to 55% in 3-mm segments). CONCLUSION: These findings indicate that taper is an important consideration in the design of vascular access grafts.

Correlation between angiographic runoff and intraoperative hydraulic impedance with regard to graft patency.

The aim of this study was to evaluate the correlation between peripheral runoff estimated by the SVS/ISCVS scoring system and intraoperatively measured outflow. Sixty-six patients received 27 femoropopliteal and 39 femorocrural ePTFE grafts. During the operation, peripheral resistance and hydraulic impedance were measured by means of the extracorporeal-bypass-flow method. Angiographic runoff was estimated according to the revised SVS/ISCVS system. Patients were entered in a graft surveillance program and patency was calculated after 3 years. The relation between the angiographic runoff score and graft patency as well as correlations between hemodynamic data, peripheral resistance, and hydraulic impedance were calculated. Primary and secondary patency rates for femoropopliteal grafts were 44% and 60% and those for femorocrural bypasses were 35% and 45%. Mean angiographic vessel diameters for above-knee and below-knee popliteal arteries were 0.51 +/- 0.02 mm and 0.47 +/- 0.04 mm. Diameters of crural arteries were 0.34 +/- 0.03 mm (posterior tibial artery), 0.27 +/- 0.02 mm (anterior tibial artery) and 0.26 +/- 0.21 mm (peroneal artery). The differences in diameter between popliteal and crural grafts were statistically significant ( p < 0.01). Calculated correlations between the preoperative score and hemodynamic, resistance, and impedance values or patency rates were generally poor and statistically not significant. A statistical significant correlation was found only between SVS/ISCVS score and recipient vessel diameters. The angiographic runoff did not correlate with peripheral resistance, impedance, or patency rates. Patients with angiographically poor outflow should additionally be evaluated with duplex sonography or magnetic resonance angiography and should not be denied peripheral reconstructions.