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Purpose: To observe fluid flow patterns and measure recirculation rates of tunneled hemodialysis catheters using a mechanical model that simulates hemodialysis treatment., Materials and Methods: Nine tunneled hemodialysis catheters were evaluated using a mechanical model that simulated catheter conditions during a routine hemodialysis treatment. Objective and subjective determinants of catheter performance were measured and compared. Catheters were evaluated with blood lines connected in standard and reversed configurations using a fluid flow rate of 425 ml/min., Results: With blood lines in standard configuration the Split Cath® was the only catheter to exhibit an atypical fluid flow pattern and significant tip movement. When the blood lines were reversed, three split-tip catheters had significant tip movement. The three step-tip catheters and two symmetric tip catheters had stable fluid flow patterns and no significant tip movement with blood lines connected in standard and reverse configurations.The nine catheters had no recirculation when connected in standard configuration. When the blood lines were reversed the percentage of recirculating fluid for symmetric tip, step-tip, and split-tip catheters was 0%, 15% to 20%, and 20% to 30%, respectively. The Equistream®, Palindrome™, and Symetrex catheters had no recirculation with blood lines connected in standard or reversed configurations., Conclusions: Eight of the nine catheters evaluated in this study performed well with blood lines connected in standard configuration. When blood lines were reversed, symmetric tip and step-tip designs had more stable fluid flow patterns, less tip movement and lower recirculation rates when compared to split-tip designs.

The use of totally implantable venous access devices in radiology may be associated with complications such as occlusion of the system (because of the high density of some contrast), infection (if the port is not handled in aseptic conditions, using proper barrier protections), and mechanical complications due to the high-pressure administration of contrast by automatic injectors (so-called power injector), including extravasation of contrast media into the soft tissues, subintimal venous or myocardial injection, or serious damage to the device itself (breakage of the external connections, dislocation of the non-coring needle, or breakage of the catheter). The last problem - i.e., the damage of the device from a power injection - is not an unjustified fear, but a reality. A warning by the US Food and Drug Administration of July 2004 reports around 250 complications of this kind, referring to both port and central venous catheters and peripherally inserted central catheter systems, which occurred over a period of several years; in all cases, the damage occurred during the injection of contrast material by means of power injectors for computed tomography or magnetic resonance imaging procedures. Though the risk associated with the use of ports in radiodiagnostics is thus clear, it has been suggested that administration of the contrast material via the port may have some advantage in terms of image quality, increased comfort for the patient, and maybe more accurate reproducibility of the patient's own follow-up exams. This contention needs to be supported by evidence. Also, since many cancer patients who need frequent computed tomography studies already have totally implantable systems, it would seem reasonable to try to define how and when such systems may safely be used. The purpose of this consensus statement is to define recommendations based on the best available evidence, for the safe use of implantable ports in radiodiagnostics.

At the time of hemodialysis vascular access evaluation, many chronic kidney disease patients already have iatrogenic injury to their veins which impedes the surgical construction of an arteriovenous fistula (AVF). Achieving the important goal of a greater prevalence of arteriovenous fistulae in the US hemodialysis population will require identification of those patients prior to reaching end-stage renal disease and an educational and procedural system for preserving their veins.

To determine the efficacy of using stents and stent grafts for treatment of hemodialysis graft-related stenoses which have failed angioplasty. This retrospective study was composed of 51 patients with polytetrafluoroethylene hemodialysis grafts who underwent angioplasty of a graft-related stenosis but subsequently required insertion of a stent or stent graft. The study group included 40 patients with >30% residual stenosis and 11 patients with angioplasty-induced venous ruptures. The patient's medical records and radiology reports were reviewed. Patient demographics, indication for stent placement, and the type of stent were recorded. Stent patency was determined using Kaplan-Meier analysis. A total of 70 stents were used; most (57.7%) were deployed across the venous anastomosis. A variety of different types of stents and stent grafts were used including 26 SMART, 18 Viabahn, 13 aSpire, and 13 other stents. The technical success rate for insertion of the device was 100%. Following insertion of the device the primary patency of the vascular access was 81%, 70%, and 54% at 1, 3, and 6 months, respectively. The secondary patency of the vascular access was 89%, 82%, and 74% at 3, 6, and 12 months, respectively. The primary patency of the stent or stent graft was 96%, 93%, 87%, and 47% at 1, 3, 6, and 12 months, respectively. Stents and stent grafts are useful for salvaging failed angioplasty procedures and thereby maintaining patency of the hemodialysis graft. By inserting a stent, the resultant patency rates are similar to those following a successful angioplasty procedure. Importantly, the primary patency of the stent was substantially better than the primary patency of the entire vascular access.

Different types of complications may occur during a percutaneous vascular access procedure and the majority of these complications are caused by balloon angioplasty. These balloon angioplasty-induced complications include venous rupture, venous dissection, and the development of an acute pseudoaneurysm. Balloon tamponade is the traditional percutaneous technique for management of these complications. However, insertion of a stent or stent graft has become an increasingly popular method to quickly and effectively repair a venous injury. A stent or stent graft may provide a more effective and durable method to treat balloon angioplasty-induced complications. Unfortunately, there are few, if any, clinical studies to substantiate the advantages and cost-effectiveness of these devices and so their use remains controversial.

A procedure-related complication is an unanticipated adverse event that requires therapy. In order to analyze frequency and severity of complications in the process of quality assurance, it is useful to have a classification of complications, indicating the type and severity. The Clinical Practice Committee of American Society of Diagnostic and Interventional Nephrology has developed a Classification of Complications relating to Hemodialysis Vascular Access Procedures, based on the system first proposed by Beathard in 2006. In this system, the "type" refers to the procedure being performed or vessel entered, and the "grade" is based on the intensity of medical care needed to address the complication. This publication describes 10 Types and 4 Grades of complications.

Purpose: To evaluate the safety and effectiveness of retrieval of the Günther Tulip inferior vena cava (IVC) filter., Materials and Methods: This was a nonrandomized, single-armed, multicenter prospective investigation. Patients at temporary high risk for pulmonary embolism (PE) or deep vein thrombosis (DVT) who did not require a permanent filter were eligible. Forty-one patients received 42 Günther Tulip filters: 22 men and 19 women with a mean age of 47.7 years. Indications for filter placement included prophylaxis, PE, and DVT. Three months after filter retrieval, contrast agent-enhanced computed tomography of the abdomen, jugular vein ultrasonography, and clinical follow-up were performed., Results: The filter retrieval rate was 57% (23 of 41). Günther Tulip filters were removed at a mean of 11.1 days (range, 2-14 d). The technical and clinical success rates for filter retrieval were both 100%. One placement complication and two protocol deviations occurred. These patients were excluded in terms of retrieval-related outcomes. One case of PE occurred with a filter in place, and one filter migrated to the heart. There were no acute complications caused by filter retrieval. At 3-month follow-up, there was no recurrent PE, DVT, jugular vein occlusion, or IVC stenosis or occlusion., Conclusion: In this multicenter study, retrieval of the Günther Tulip filter was safe and without recurrent thromboembolic events or evidence of IVC or jugular vein damage at 3-month follow-up.

Purpose: This two-part prospective investigation was designed to determine the balloon inflation pressures required to dilate stenoses associated with hemodialysis grafts and evaluate the burst pressures of five different angioplasty balloons., Materials and Methods: Eighty-nine patients with dysfunctional hemodialysis grafts were enrolled and underwent fistulography. The diagnostic studies revealed 104 stenoses, which were treated with balloon angioplasty. The characteristics of these stenoses and the balloon inflation pressures required to dilate the lesions were recorded. In part two of this investigation, the burst pressures of five different angioplasty balloons were evaluated immediately after their use during angioplasty procedures. Twenty-five balloons of each type were inflated until the balloon burst or 30 atm of pressure was achieved. Several different statistical tests were used to analyze the data set., Results: The mean balloon inflation pressure required to dilate all 104 stenoses was 17.2 atm. Subgroup analysis revealed that the mean balloon inflation pressure required to dilate 75 venous anastomotic stenoses was 17.9 atm and that a mean pressure of 15.6 atm was required to dilate 29 stenoses located within the native outflow veins. The angioplasty balloon burst pressure experiments revealed that the majority of the tested balloons can be inflated to pressures 5-6 atm greater than the manufacturers' rated burst pressures. However, the margin of safety for overinflation was variable among the balloons tested, and angioplasty balloons experience fatigue with repeated inflations., Conclusion: The majority of stenoses associated with hemodialysis grafts can be successfully dilated with use of available high-pressure angioplasty balloons.

Purpose: To compare the effectiveness and safety of use of the peripheral cutting balloon (PCB) versus standard percutaneous transluminal angioplasty (PTA) for the treatment of hemodialysis-related stenoses., Materials and Methods: This prospective, randomized multicenter clinical trial included 340 patients with stenotic or thrombosed hemodialysis grafts who were randomized to receive treatment with the PCB or PTA for venous outflow stenosis. One hundred seventy-three patients underwent treatment with the PCB, 101 with stenotic grafts and 72 with thrombosed grafts. PTA was used to treat 167 patients, 94 patients with stenotic grafts and 73 with thrombosed grafts. The follow-up period extended for 6 months., Results: The procedural success rates were 80.8% and 75.4% for the PCB and PTA groups, respectively (P = .24). With use of the PCB, the primary patency rates of the target lesions were 84.3%, 65.8%, and 47.9% at 1 month, 3 months, and 6 months, respectively. With PTA, the primary patency rates of the target lesions were 77.7%, 63.4%, and 40.5% at 1 month, 3 months, and 6 months, respectively. The primary patency rates of the entire vascular access circuit were 82.6%, 61.0%, and 43.3% at 1 month, 3 months, and 6 months, respectively, with use of the PCB. For patients who were treated with PTA, the primary patency rates of the vascular access circuit were 75.9%, 61.0%, and 36.3% at 1 month, 3 months, and 6 months, respectively. When comparing the PCB and PTA, there was no difference in the 6-month primary patency rates in the target lesion (P = .373) or the entire vascular access circuit (P = .531). There were nine device-related complications in the PCB group (5.2%): five venous ruptures (2.9%), three venous dissections (1.7%), and one case of thrombosis (0.6%). There were no device-related complications in the PTA group., Conclusion: This prospective, randomized trial comparing use of the PCB versus standard PTA for treatment of hemodialysis-related venous stenoses demonstrated that the PCB provides equivalent 6-month patency to PTA for stenotic and thrombosed grafts.

Purpose: Air embolism is a rare but potentially fatal complication that may occur during the insertion of a central venous catheter. A valved peelable introducer sheath was developed to reduce the likelihood of an air embolus. This study was performed to determine the rate of air flow through this valved introducer sheath under different conditions that may be encountered in a clinical setting., Materials and Methods: A 16-F-diameter valved peelable introducer sheath was used for all experiments. A bench-top testing system was constructed that consisted of a vacuum source, a mass flow meter, and a digital vacuum gauge. A coupling device with a pneumatic O-ring was used to seal and connect the distal end of the introducer sheath to the testing system. A vacuum of -5 mm Hg was applied to the sealed distal end of the sheath to simulate physiologic conditions. The rate of air flow through the valved sheath was measured under three different conditions; (i) valve open, (ii) valve closed, and (iii) valve open but with the sheath manually pinched. Thirty air flow measurements were performed for each of the three test conditions., Results: When the valve was in the open position, the mean rate of air flow through the introducer sheath was 417.2 mL/sec (range, 415.5-419.7 mL/sec). When the valve was in the closed position, the mean rate of air flow was 0.004 mL/sec (range, 0.000-0.067 mL/sec). When the valve was open but the sheath was manually pinched, the mean rate of air flow through the sheath was 31.7 mL/sec (range, 23.0-38.8 mL/sec). During the 90 testing procedures, the mean vacuum was -5.10 mm Hg (range, -5.00 to -5.45 mm Hg)., Conclusions: This bench-top study revealed that a massive amount of air flowed through the open 16-F introducer sheath when it was subjected to a vacuum of -5 mm Hg, a situation that may occur under normal physiologic conditions. The rate of air flow could be decreased by aggressively pinching the sheath but the rate of air flow was still substantial. This study demonstrated that the addition of a sophisticated valve mechanism can essentially eliminate air flow through a peelable introducer sheath.

Purpose: To review the author's early experience with stent grafts to repair hemodialysis graft-related pseudoaneurysms., Materials and Methods: Eleven patients had undergone insertion of a stent graft to repair a pseudoaneurysm arising from a PTFE hemodialysis graft. The study group consists of seven women and four men with a mean age of 50.7 years. The primary indications for stent graft placement were: rapid enlargement of a pseudoaneurysm in four patients, difficulty with cannulating the graft in two patients, high risk of acute rupture in three patients, persistent bleeding from the pseudoaneurysm in one patient, and one was incidentally discovered during diagnostic fistulography. In 10 of the 11 patients, the pseudoaneurysm arose from the arterial limb of a loop-configuration graft. A stent graft was successfully deployed in all patients. The radiological and surgical records were reviewed., Results: The Viabahn endoprosthesis was successfully inserted and deployed in all 11 patients. Six patients underwent subsequent interventions, which ended primary patency at 39 days, 40 days, 63 days, 104 days, 120 days, and 327 days after insertion of the stent graft. However, no additional interventions have been performed in five patients and primary patency continues. In these five patients the interval of continuing primary patency is 55 days, 92 days, 103 days, 139 days, and 196 days. In this small group of patients the primary patency rate is 71% at 3 months and 20% at 6 months., Discussion: Early experience has demonstrated that a stent graft can successfully exclude a pseudoaneurysm from a hemodialysis graft and may prevent further enlargement and decrease the likelihood of rupture. However, in two of these 11 patients, the large pseudoaneurysm remained problematic and required subsequent surgical repair.

We are entering a new era for the management of hemodialysis grafts and fistulae. The hallmark of this new era will be the use of quantitative, hemodynamic parameters to optimize vascular access function and improve the results of our endovascular interventions. The implementation of vascular access surveillance programs has not only decreased the incidence of vascular access thrombosis, but also has provided new insights into the hemodynamic performance of grafts and fistulae. The measurement and analysis of intra-access blood flow has proven useful for the early detection of developing stenosis, and also provides a quantitative method to assess the results of our endovascular interventions. In the future, the use of quantitative hemodynamic measurements will play an increasingly important role in our evaluation and treatment of hemodialysis grafts and fistulae.

Purpose: To determine if intragraft blood flow measurements correlate with the anatomical characteristics of stenoses found during diagnostic fistulography., Materials and Methods: This investigation was a retrospective review of 40 patients with decreased intragraft blood flow (<600 mL/min) in patent polytetrafluoroethylene hemodialysis grafts who underwent diagnostic fistulography and angioplasty. Intragraft blood flow was measured with the ultrasonic dilution technique. The fistulogram images were reviewed and the anatomic characteristics of all stenoses were measured and recorded. These characteristics were correlated with the intragraft blood flow values., Results: The mean intragraft blood flow was 476 mL/min (range, 270-600 mL/min). Fistulography revealed a total of 71 stenoses and all 40 patients had at least one lesion with > 50% stenosis. There was no correlation between the intragraft blood flow and the location, length, or number of stenoses. There was a moderate inverse correlation between the intragraft blood flow and the degree of stenosis (P =.08). Fifty-nine stenoses were treated with angioplasty. The mean postangioplasty blood flow was 796 mL/min (range, 470-1565 mL/min). The mean change in blood flow after angioplasty was 311 mL/min (range, 15-1154 mL/min) There was no association between the change in blood flow after angioplasty and the number, length, or degree of residual stenosis., Conclusion: Intragraft blood flow < 600 mL/min is an excellent predictor of the presence of at least one significant (>/=50%) stenosis. There was an inverse correlation between intragraft blood flow and the degree of stenosis. There was no association between the intragraft blood flow and the location, length, or number of stenosis.

Purpose: To evaluate an approach to the treatment of iliofemoral deep vein thrombosis (DVT) that included pharmacomechanical catheter-directed thrombolysis with reteplase and the Helix mechanical thrombectomy device, followed by early stent placement., Materials and Methods: During 3-year period, 23 symptomatic limbs in 18 patients with iliofemoral DVT were treated with reteplase catheter-directed thrombolysis. After an initial infusion of 8 to 16 hours, any residual acute thrombus over a long segment (> 10 cm) was treated by maceration with use of the Helix thrombectomy device. Residual short-segment (< 10 cm) iliac vein thrombus and/or stenosis were treated with stent placement. Technical success, clinical success, complications, thrombolytic infusion time, total thrombolytic agent dose, fibrinogen level changes, and late limb status were retrospectively analyzed., Results: Technical success was achieved in 23 of 23 limbs (100%). Clinical success was achieved in 22 of 23 limbs (96%). Complete or partial thrombolysis was observed in 19 of 23 limbs (83%). Major bleeding was observed in one patient (6%) and necessitated blood transfusion. Mean per-limb thrombolytic infusion time and total dose were 19.6 hours +/- 8.1 and 13.8 U +/- 5.3 reteplase, respectively. Mean serum fibrinogen nadir and percentage drop in serum fibrinogen were 282 mg/dL +/- 167 and 47% +/- 24%, respectively. Late (mean, 19.8 +/- 11.6 months) modified Venous Disability Scores were 0 (none) for six limbs, 1 (mild) for 10 limbs, 2 (moderate) for two limbs, and 3 (severe) for no limbs., Conclusion: In a preliminary experience, pharmacomechanical catheter-directed iliofemoral DVT thrombolysis with early stent placement was safe and effective.

This brief technical report describes our initial experience using the FlowGuard valved introducer sheath during the insertion of tunneled hemodialysis catheters in 15 patients. The incorporation of a silicone valve into the introducer sheath is intended to minimize blood loss and decrease the risk of air embolism during the catheter insertion procedure. Our preliminary experience demonstrated that the FlowGuard sheath is a substantial improvement when compared to standard introducer sheaths. However, an asymptomatic air embolus did occur in one patient. This article describes several caveats for the use of this new product.

Purpose: To evaluate the authors' preliminary experience with use of endovascular methods to treat inferior vena cava (IVC) thrombosis in patients with IVC filters., Materials and Methods: Catheter-directed thrombolysis, balloon maceration, mechanical thrombectomy, and stent placement were used to treat 10 patients with thrombosis of filter-bearing IVCs causing symptoms in 18 limbs. Procedural challenges, technical and clinical success, complications, postprocedural filter status, and postprocedural pulmonary embolism (PE) prophylaxis were monitored., Results: Technical and clinical success were achieved in 15 of 18 (83%) and 14 of 18 symptomatic limbs (78%), respectively. Major bleeding (muscular hematoma) occurred in one patient (10%). Postprocedural PE prophylaxis included anticoagulation (n = 8) and placement of a new filter into a newly placed Wallstent (n = 1). During clinical follow-up, no clinically detectable PE was observed. Data pertaining to late limb status were available at a median of 19 months (range 1-46 months) follow-up in seven patients: three patients were asymptomatic, two patients had ambulatory edema only, one patient had constant mild edema, and one patient had constant severe edema. Postprocedural filter stability was radiographically documented at a median of 255 days (range, 4-1021 d) of follow-up., Conclusion: Endovascular recanalization of the occluded IVC is feasible even in the presence of an IVC filter.

There is continuing debate among physicians, nurses, and federal regulatory agencies regarding the correct position for the tip of a central venous catheter. The traditional approach has been to place the catheter tip within the superior vena cava. However, many interventionalists believe that the performance and durability of the catheter will be improved by positioning the catheter tip within the upper right atrium. Recently, this variability in clinical practice has become an increasingly divisive issue among physicians who insert these catheters and nurses who use them. This article is intended to elucidate the controversial issues and provide a brief review of the extensive literature on this important topic.

Treatment of a thrombosed hemodialysis graft is an ideal application for a mechanical thrombectomy device. The soft, acute thrombus contained within the graft can be quickly macerated and removed with minimal risk of damaging native vascular endothelium. There are no universally accepted techniques for using mechanical thrombectomy devices to treat a thrombosed vascular access. To the contrary, there are a variety of thrombectomy methods that are currently utilized by interventional radiologists. Each device has its own niche and is best utilized for certain specific situations. A busy interventionalist should be familiar with several of these thrombectomy devices to most effectively treat the variety of clinical problems that may be encountered., (Copyright 2003 Elsevier Inc. All rights reserved.)

Purpose: To retrospectively review the incidence and types of arterial problems associated with dysfunctional hemodialysis grafts in patients who are at high risk for peripheral arterial disease., Materials and Methods: During the 1-year period from February 2001 to February 2002, 40 patients with polytetrafluoroethylene hemodialysis grafts underwent upper extremity arteriography to evaluate arterial inflow to the vascular access. The indication for arteriography was based on the presence of at least two of the following risk factors for peripheral vascular disease: diabetes mellitus, hypertension, and age greater than 65 years. Thirty-three of the 40 patients were women and the median age was 65 years. Thirty-three patients had forearm loop-configuration grafts and seven had upper-arm grafts., Results: Upper extremity arteriography revealed 13 arterial inflow lesions in 11 of the 40 patients (28%). Ten patients had stenoses at the arterial anastomosis. Two of these patients also had stenoses in the brachial artery. One patient had a single stenosis in the brachial artery. Eight of the 11 patients (73%) underwent angioplasty of seven arterial anastomotic stenoses and three brachial artery stenoses. Comparative analysis revealed that the presence of risk factors for atherosclerotic disease did not correlate with an increased incidence of arterial inflow problems. Surprisingly, patients with diabetes mellitus had a decreased likelihood (P =.03) of having an arterial abnormality., Conclusion: Although the incidence of arterial anastomotic stenoses in our study group was higher than previously reported, patients undergoing hemodialysis who have risk factors for peripheral vascular disease do not have a high prevalence of native arterial lesions.

Purpose: To evaluate the use of adjunctive mechanical thrombectomy (MT) with pharmacologic catheter-directed lower extremity venous thrombolysis., Materials and Methods: Catheter-directed thrombolysis with adjunctive MT was used to treat 28 symptomatic limbs in 20 patients (22 procedures) with lower extremity deep vein thrombosis (DVT) between August 1997 and July 2001. Procedural success, major bleeding, thrombolytic infusion time, and total thrombolytic agent dose were recorded., Results: Procedural success was achieved in 23 of 28 limbs (82%). Fifteen patients (18 limbs) received iliac vein stents. Major bleeding was observed after three of 22 procedures (14%) and resulted in transfusion in two patients and endometrial ablation in the third patient. Mean per-limb infusion time was 16.8 hours +/- 12.8. Mean per-limb total doses were lower than those reported in published studies of DVT thrombolysis: 2.67 million U +/- 1.60 urokinase, 18.4 mg +/- 10.7 tissue plasminogen activator, and 13.8 U +/- 6.9 reteplase. Venographic analysis demonstrated minimal thrombus removal (26.0% +/- 24.1) when using MT alone, compared with substantial thrombus removal (62.0% +/- 24.9) when using MT after pharmacologic thrombolytic agents had been administered (P =.006)., Conclusion: The use of adjunctive MT to augment pharmacologic catheter-directed DVT thrombolysis provides comparable procedural success and may reduce the required thrombolytic dose and infusion duration.

Purpose: To retrospectively determine the incidence and outcome of angioplasty-induced ruptures that occurred during treatment of hemodialysis graft-related stenoses., Materials and Methods: During a five year period 1222 patients with dysfunctional or thrombosed polytetrafluoroethylene (PTFE) hemodialysis grafts underwent angioplasty procedures at our institution. Angioplasty-induced vascular ruptures occurred in 24 (2.0%) patients. The locations of these ruptures were: basilic vein (10), venous anastomosis (7), cephalic vein (5), brachial vein (1) and intragraft (1). The mean length of the treated stenoses was 2.4 centimeters., Results: Manual compression was used to treat the vascular rupture in ten patients. One patient was treated with endovascular balloon tamponade and one patient underwent stenting of the rupture site. Despite the rupture, 15 patients had completion of the angioplasty procedure. In nine patients the procedure was abandoned due to persistent stenosis at the rupture site. There were no major complications as a result of these ruptures. Follow-up was available in ten of these patients. All ten underwent at least one successful hemodialysis treatment. In five of these patients the hemodialysis graft failed within 30 days after the rupture. The mean primary patency following rupture in the ten patients with follow-up was 87.5 days (range 5 - 225 days)., Conclusion: The incidence of angioplasty-induced vascular rupture of hemodialysis-related stenoses is low and despite the injury, the majority (62%) of procedures can be completed. However, in our experience the long-term patency of the vascular access was suboptimal.

Endovascular interventions have replaced surgical repair as the primary treatment of the failing or thrombosed vascular access. However, endovascular and surgical techniques are complementary: the limitations of one are the strengths of the other. Endovascular management of access-related problems is a critical component of a successful vascular access monitoring program. The identification and early treatment of developing stenoses, before access thrombosis are essential roles that are ideally suited to percutaneous, image-guided techniques. Despite recent advances in endovascular techniques and devices, angioplasty continues to be the primary method for treatment of access-related stenoses. When appropriate lesions are treated, angioplasty is a fast, easy, and safe procedure that can extend to patency of a hemodialysis graft or fistula., (Copyright 2002 by the National Kidney Foundation, Inc.)

Purpose: To retrospectively review the complications reported during percutaneous thrombectomy procedures performed on polytetrafluoroethylene hemodialysis grafts., Materials and Methods: A retrospective review revealed that 935 percutaneous thrombectomy procedures were performed at our institution between January 1993 and June 2001. The type and number of procedures include: Arrow PTD (527), pulse-spray with urokinase (240), Amplatz Thrombectomy Device (96), AngioJet (17), Oasis (15), Hydrolyser (10), Endovac (7), Lyse and Wait (7), Thrombex (6), Cragg brush (6), Castaneda brush (4). Complications were reported to have occurred in 31 patients. The radiology reports and medical records of these patients were reviewed., Results: The overall complication rate was 3.3%. The type and number of complications included: rupture of a vein during angioplasty (13), severe cardiopulmonary distress (4), arterial emboli (4), rigors related to urokinase (3), minor bleeding (2), hypoxia with chest pain (2), other assorted complications (3). There was one death resulting from a fall from the angiography table immediately following the procedure. There were 12 minor complications, requiring minimal treatment, and 19 major complications that altered the course of the procedure or treatment of the patient., Conclusion: The most common complication was angioplasty-induced rupture of the vein or graft. The most severe complications occurred immediately following dislodgement of the arterial plug and were likely due to acute pulmonary embolization.

Purpose: The goals of this investigation were to evaluate the accuracy and reliability of the Angioflow meter system with use of in vitro and in vivo methods and to compare it to the standard Transonics HD01 system in a clinical setting., Materials and Methods: The Angioflow meter system consists of a 6-F endovascular catheter and a laptop computer containing proprietary software for this application. Bench-top testing with use of a flow model was performed to determine the accuracy of the Angioflow meter system. Initial in vivo studies were performed with use of an animal model to assess the endovascular performance of the Angioflow meter system. Subsequently, a human clinical trial was performed to compare the Angioflow meter to the standard Transonics HD01 system. Twenty-five patients with dysfunctional (<600 mL/min) hemodialysis grafts were referred for fistulography and angioplasty. Intragraft blood flow measurements were obtained before and after angioplasty with use of both the Angioflow meter system and the Transonics HD01 system. A comparison of the two systems was performed., Results: Bench-top testing and animal studies demonstrated an excellent (r =.98) correlation between the measurements of the Angioflow meter and volumetric flow measurements. In the clinical trial, there was reasonable correlation (r =.72) between the blood flow measurements obtained with use of the Angioflow meter and Transonics HD01 system. The reproducibility of consecutive measurements with the Angioflow meter was excellent (r =.98). The mean increase in intragraft blood flow after angioplasty was 320 mL/min., Conclusion: The Angioflow meter is an accurate and reliable endovascular device for measuring intragraft blood flow during interventional procedures. Use of this catheter-based system should prove beneficial for quantifying the success of endovascular interventions, the assessment of arterial inflow, and identification of inconspicuous lesions.

This article describes a method to remove thrombus from pseudoaneurysms associated with hemodialysis grafts during a percutaneous mechanical thrombectomy procedure. This effective and easily performed technique involves manual compression of the pseudoaneurysm during activation of the Arrow Percutaneous Thrombolytic Device. The authors describe their clinical experience with use of this technique to treat 18 patients during percutaneous mechanical thrombectomy procedures. In addition, the development, morphology, and management of hemodialysis graft-related pseudoaneurysms are discussed.

Tunneled catheters serve as interim access during maturation of a graft or fistula, or as a permanent vascular access in those patients who have exhausted their traditional access sites. However, bacteremia rates are high in patients with chronic catheters and indiscriminate removal of catheters during bacteremia increases morbidity and costs. A method to identify whether a catheter was colonized with the offending bacteria, without requiring catheter removal is desirable. We compared endoluminal brushing and heparin aspiration, to detect catheter colonization, in 24 asymptomatic patients undergoing elective tunneled hemodialysis catheter removal. The incidence of catheter colonization was highly correlated with catheter duration of inverted exclamation markY 30 days (p=0.03). Staphylococcus epidermidis represented 68% of the organisms isolated. No other organism accounted for more than 7% of the total. Fifteen (62.5%) of the 24 catheters had positive cultures. Eleven of the catheters were positive by culture of heparin aspirate and eight were positive by endoluminal brushing. Only four of the catheters were positive by both methods. The arterial lumen was more likely to have positive cultures than the venous lumen using either method. In this prospective investigation of tunneled hemodialysis catheters in asymptomatic patients we have demonstrated that a heparin aspirate sample is more likely to detect catheter colonization than a sample obtained using an endoluminal brush. Furthermore, 75% of catheters present for more than 30 days were colonized. Further study is needed to determine if the heparin aspirate method could be used in patients with bacteremia to accurately identify catheters that need removal.

Purpose: To determine the clinical consequences of air embolism occurring during insertion of central venous catheters., Materials and Methods: A computer search of our interventional radiology database revealed that 11,583 central venous catheters were inserted between January 1, 1995 and August 1, 2000: 7,178 were nontunneled and 4,404 were tunneled. Air embolism was reported to have occurred in 15 patients. Air embolization was recognized by audible air aspiration during catheter insertion or by fluoroscopic visualization of air within the right atrium or pulmonary artery. The radiology reports and medical records of these 15 patients were reviewed., Results: All 15 patients had an air embolism occur during insertion of a tunneled central venous catheter. These included eight Ash catheters, five chest wall ports, one Tesio catheter, and one Pheres-Flow catheter. Four patients remained asymptomatic. Six patients had mild symptoms that quickly resolved with supplemental oxygen. Four had moderate symptoms that also resolved with supplemental oxygen. One patient died acutely as a result of the air embolism., Conclusion: Air embolism is a rare but potentially fatal complication of central venous catheter procedures. In our series, all occurred during insertion of a tunneled catheter through a peel-away sheath. The administration of supplemental oxygen was an effective treatment in the majority of patients.

Background: The anatomic success of percutaneous angioplasty of venous stenosis is determined by the improvement in cross-sectional diameter of the vessel. A successful outcome is defined as a residual stenosis of <30%. The purpose of this study was to determine whether the angiographic assessment of a venous stenosis correlates with the change in graft blood flow following angioplasty., Methods: Twenty-two hemodialysis patients with decreased intragraft blood flow (<700 mL/min) underwent diagnostic fistulography and angioplasty. All grafts were patent at the time of the procedure. Intragraft blood flow was measured before and after angioplasty using the ultrasonic dilution technique. Change in graft blood flow after angioplasty was correlated to the morphologic changes of the treated stenosis., Results: The mean preangioplasty and postangioplasty graft blood flows were 457 +/- 136 and 818 +/- 202 mL/min, respectively. The mean degree of stenosis before angioplasty was 74 +/- 15% and 18 +/- 14% after dilation (P < 0.001). The only variable that significantly correlated with postangioplasty blood flow was preangioplasty flow (r2 = 0.22, P < 0.001). The postangioplasty blood flow was not significantly different than the highest recorded blood flow measured in that graft (798 +/- 213 mL/min, P = NS). There was no significant correlation between the change in blood flow and the change in percentage of stenosis., Conclusion: Following angioplasty of a venous stenosis, the graft blood flow is most closely predicted by the preprocedural blood flow and is similar to the highest recorded blood flow ever measured in that graft. Angiographic criteria to assess the success of angioplasty are not predictive of changes in blood flow.

Angioscopy provides a magnified, real-time, 360-degree view of the endoluminal surface of blood vessels, yielding unique information that is often complementary to conventional angiography. This unique perspective can significantly enhance one's perception and appreciation of endovascular disease. Although angioscopy is primarily used as a research tool, its ability to characterize accurately the morphology and color of atherosclerotic lesions may lead to improved treatment and better clinical outcomes., (Copyright 2001 by W.B. Saunders Company)

Purpose: To use angioscopy to evaluate and compare the amount of residual thrombus and endoluminal wall damage in hemodialysis grafts after percutaneous thrombectomy procedures., Materials and Methods: Thirty-nine thrombectomy and angioscopy procedures were performed in 35 patients. Percutaneous thrombectomy methods included eight different mechanical thrombectomy devices and the "lyse and wait" technique. Videotaped images of 33 angioscopic examinations were independently reviewed by three radiologists. Two parameters-the amount of residual thrombus and degree of endoluminal wall damage-were scored on a scale of 1 to 5. Data were initially analyzed to validate the grading system and then further studied to compare the different thrombectomy techniques., Results: The Spearman rank order analysis validated the data pertaining to the amount of residual thrombus (r = 0.71, P < .0001), but there was poor correlation between reviewers regarding the degree of endoluminal wall damage. Combined scores from three reviewers revealed that the Cragg brush and Percutaneous Thrombectomy Device (PTD) left the smallest amounts of residual thrombus. The other methods tested, listed by increasing amount of residual thrombus, were the Endovac, Hydrolyser, Amplatz Thrombectomy Device, AngioJet, Oasis, and the lyse and wait technique. There were two complications related to angioscopy procedures., Conclusion: Subjective observations reveal that wall-contact thrombectomy devices leave less residual thrombus than hydrodynamic devices, aspiration devices, or the lyse and wait technique.

Purpose: To compare the clinical effectiveness of the AngioJet F105 rheolytic catheter to that of surgical thrombectomy for the treatment of thrombosed hemodialysis grafts., Materials and Methods: This was a multicenter, prospective, randomized trial comparing technical success, primary patency, and complication rates. A total of 153 patients were enrolled: 82 patients in the AngioJet group and 71 patients in the surgical thrombectomy group. Patient follow-up was performed 24-48 hours, 1 month, and 6 months after the procedures., Results: Technical success, as defined by the patient's ability to undergo hemodialysis treatment, was 73.2% for the AngioJet group and 78.8% for the surgical thrombectomy group (P = .41). The primary patency rates of the AngioJet group were 32%, 21%, and 15% at 1, 2, and 3 months, respectively. The primary patency rates for the surgical group were 41%, 32%, and 26% at 1, 2, and 3 months, respectively. This difference approached statistical significance (P = .053). The groups had similar complication rates-14.6% in the AngioJet group and 14.1% in the surgery group-although the surgery group had more major complications (11.3%). In the AngioJet group, there was a transient increase in plasma-free hemoglobin, which normalized within 24-48 hours., Conclusions: The AngioJet F105 catheter provides similar clinical results when compared to surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. The difference in patency rates between these two techniques approached statistical significance. In addition, results of both thrombectomy methods were inferior to those suggested by the Dialysis Outcomes Quality Initiative guidelines.

Purpose: This retrospective study was performed to investigate the authors' clinical observations that suggest that Tesio hemodialysis catheters may initially have suboptimal blood flow rates, which improve spontaneously after several hemodialysis treatment sessions., Materials and Methods: Sixty Tesio twin hemodialysis catheters were placed in 49 patients during a 2-year period. Thirty twin catheters were placed by radiologists, and 30 were placed by surgeons. The catheter blood flow rates and catheter line pressures, which were recorded during each of the first five hemodialysis treatment sessions, were reviewed and analyzed to determine the performance of each catheter during the first five hemodialysis treatments. In addition, the authors compared the site of catheter placement and responsible service (surgery or radiology) using this catheter performance data., Results: Twenty-six catheters (43%) provided adequate blood flow (250 mL/min) throughout the first five hemodialysis sessions. Twenty-six catheters (43%) had inadequate or variable blood flow rates, some of which improved without intervention. Eight catheters (13%) required an intervention before the first five hemodialysis sessions had been completed. Right-sided catheters performed better than left-sided catheters. There was no difference in performance between catheters placed by surgeons and those placed by radiologists., Conclusion: This investigation supports the authors' suspicion that some Tesio catheters may have inadequate initial performance but the blood flows can improve, without intervention, during the first five hemodialysis sessions/2 weeks of use.

Purpose: To analyze the results of percutaneous drainage of fluid collections in the extremities., Materials and Methods: From 1990-1997, 28 patients aged 14-90 years underwent percutaneous drainage of 33 fluid collections in the extremities; two patients underwent multiple drainages. Fluid collections were in the hip-groin area (n = 16), thighs (n = 6), buttocks (n = 6), knees (n = 3), calf (n = 1), and axilla (n = 1). Three intraarticular collections were included. The patients who had undergone prior procedures were eight who had undergone surgical drainage, 10 who had undergone needle aspiration, and one who had undergone surgical débridement. The two most common guidance methods of catheter placement were ultrasound localization and fluoroscopy., Results: The average drainage duration was 18.2 days (range, 1-93 days). The estimated cavity sizes were 4-733 cm3. Purulent fluid was drained in 13 patients. Staphylococcus aureus was the most commonly identified organism (n = 9). Nine patients had postoperative lymphoceles; five of these patients underwent sclerotherapy. Two (7%) patients had two complications, one of which was major. Failure occurred in four (16%) of 25 patients; two needed repeat drainage for recurrence, and two needed subsequent surgery. Success could not be determined in three patients who were lost to follow-up., Conclusion: Percutaneous drainage of fluid collections in the extremities is an effective alternative to open-incision drainage in inpatients and outpatients.