PubMed Health⌕ Search

Biomedical subjects

Timothy W I Clark

Publications and source records attributed to Timothy W I Clark.

At least 19 recordsLinked to original sources
PubMed2006

Salvage of nonmaturing native fistulas by using angioplasty.

PURPOSE: To retrospectively review outcomes following angioplasty of nonmaturing autogenous hemodialysis fistulas. MATERIALS AND METHODS: Institutional review board exemption was received for this HIPAA-compliant retrospective study; informed consent was waived. During 48 months, 101 patients underwent fistulography for percutaneous salvage of nonmaturing native fistulas. Clinical and technical success, need for secondary interventions, and complications were recorded according to consensus definitions. Patency following angioplasty was estimated with the Kaplan-Meier technique. Patient age, sex, ethnicity, fistula age, fistula type, number of stenoses, maximal angioplastic balloon diameter used, and presence of palpable thrill following angioplasty were examined as predictors of primary patency of the fistula following intervention by using Cox proportional hazards model. RESULTS: Mean patient age was 58 years; 35% were women. Median time from fistula creation to fistulography was 2.5 months. Hemodynamically significant (>50%) stenoses were identified in 88% (89 of 101) of patients; angioplasty was attempted in 96% (85 of 89). Technical success was achieved in 92% (78 of 85) of fistulas following angioplasty; clinical success of normal hemodialysis with total access blood flow of more than 500 mL/min occurred following 88% (75 of 85) of angioplastic interventions. No major and two minor complications occurred. Mean primary unassisted patency at 3, 6, and 12 months was 60%+/-6% (95% confidence interval), 45%+/-6%, and 34%+/-6%, respectively. Additional angioplasty (n=12), stent placement (n=1), or thrombectomy (n=1) during subsequent interventions resulted in mean secondary patency at 3, 6, and 12 months of 82%+/-4%, 79%+/-5%, and 75%+/-6%, respectively. Patients without thrill following angioplasty were more than twice as likely to lose patency as patients with thrill (P=.035). No relationship was seen between primary patency and other predictors examined. CONCLUSION: Early fistulography enables identification of underlying areas of stenosis in nonmaturing fistulas, which can be safely and effectively treated with angioplasty. With continued surveillance and repeat interventions, functional patency can be sustained in the majority of fistulas.

Angioplasty↗
PubMed2006

Asymptomatic central venous stenosis in hemodialysis patients.

PURPOSE: To retrospectively evaluate the natural history of high-grade (>50%) asymptomatic central venous stenosis (CVS) in hemodialysis patients and the outcome of serial treatment of CVS with percutaneous transluminal angioplasty (PTA). MATERIALS AND METHODS: The institutional review board granted exemption for this retrospective study, the need for informed consent was waived, and all data collection was in compliance with HIPAA. Patients with hemodialysis access requiring maintenance procedures between 1998 and 2004 and incidentally found to have ipsilateral (> or =50%) CVS were identified from a departmental database. Thirty-five patients (19 men, 16 women; mean age, 58.7 years) with 38 grafts met inclusion criteria, and 86 venograms were reviewed. CVS was measured by using venograms obtained before and after PTA, if performed. Patients with arm swelling, multiple CVS, indwelling catheters, and stents at the first encounter were excluded. CVS progression was calculated by dividing the change in the degree of stenosis by the time between venographic examinations. Wilcoxon rank sum test was used to evaluate differences in rate of CVS progression between treated and nontreated patients. RESULTS: Mean degree of CVS before intervention was 71% (range, 50%-100%). Sixty-two percent (53 of 86) of lesions had associated collateral vessels; 28% (24 of 86) of CVSs were not treated. Mean degree of stenosis in this group was 72% (range, 30%-100%); mean progression was -0.08 percentage point per day. No untreated CVS progressed to symptoms, stent placement, or additional CVS. Seventy-two percent (62 of 86) of CVSs were treated with PTA. Mean degree of stenosis in this group was 74% (range, 50%-100%) before and 40% (range, 0%-75%) after treatment; mean progression was 0.21 percentage point per day after treatment (P = .03). Six (8%) of 62 treatments were followed by CVS escalation; one patient developed arm swelling, four required stents, and four developed additional CVS. CONCLUSION: PTA of asymptomatic CVS greater than 50% in the setting of hemodialysis access maintenance procedures was associated with more rapid stenosis progression and escalation of lesions, compared with a nontreatment approach.

Angioplasty, Balloon↗
PubMed2006

Portal flow and arterioportal shunting after transjugular intrahepatic portosystemic shunt creation.

PURPOSE: It was postulated that a transjugular intrahepatic portosystemic shunt (TIPS) produces arterioportal shunting and accounts for reversed flow in the intrahepatic portal veins (PVs) after creation of the TIPS. This study sought to quantify this shunting in patients undergoing TIPS creation and/or revision with use of a direct catheter-based technique and by measuring changes in blood oxygenation within the TIPS and the PV. MATERIALS AND METHODS: This prospective study consisted of 26 patients. Median Model for End-stage Liver Disease and Child-Pugh scores were 13 and 9, respectively. Primary TIPS creation was attempted in 21 patients and revision of failing TIPS was undertaken in five. In two patients, TIPS creation was unsuccessful. All TIPS creation procedures but one were performed with use of polytetrafluoroethylene-covered stent-grafts. Flow within the main PV (Q(portal)) was measured with use of a retrograde thermodilutional catheter before and after TIPS creation/revision, and TIPS flow (Q(TIPS)) was measured at procedure completion. The amount of arterioportal shunting was assumed to be the increase between final Q(portal) and Q(TIPS), assuming Q(TIPS) was equivalent to the final Q(portal) plus the reversed flow in the right and left PVs. Oxygen saturation within the TIPS and the PV was determined from samples obtained during TIPS creation and revision. RESULTS: Mean Q(portal) before TIPS creation was 691 mL/min; mean Q(portal) after TIPS creation was 1,136 mL/min, representing a 64% increase (P = .049). Mean Q(TIPS) was 1,631 mL/min, a 44% increase from final Q(portal) (P = .0009). Among cases of revision, baseline Q(portal) was 1,010 mL/min and mean Q(portal) after TIPS revision was 1,415 mL/min, a 40% increase. Mean Q(TIPS) was 1,693 mL/min, a 20% increase from final Q(portal) (P = .42). Arterioportal shunting rates were 494 mL/min after TIPS creation and 277 mL/min after TIPS revision, representing 30% of total Q(TIPS) after TIPS creation and 16% of Q(TIPS) after TIPS revision. No increase in oxygen tension or saturation was seen in the PV or TIPS compared with initial PV levels. Q(TIPS) did not correlate with the portosystemic gradient. CONCLUSION: TIPS creation results in significant arterioportal shunting, with less arterioportal shunting seen among patients who undergo TIPS revision. Further work is necessary to correlate Q(TIPS) with the risk of hepatic encephalopathy and liver failure.

Adult↗
PubMed2006

Radiofrequency ablation of small renal cell carcinomas using multitined expandable electrodes: preliminary experience.

PURPOSE: Radiofrequency ablation is a minimally invasive, nephron-sparing option for renal cell carcinoma (RCC) in poor surgical candidates. We report our contemporary experience with RCC radiofrequency ablation using multitined expandable electrodes along with an aggressive treatment strategy to displace adjacent viscera away from probe tines. Involution of the treatment zone was assessed over time. MATERIALS AND METHODS: Over a 36-month period, a quality-assurance database identified 22 patients with 26 sporadic RCC who underwent 43 ablations during 27 radiofrequency ablation sessions. The mean age of the cohort was 71 years (range, 47-89 y). Mean RCC diameter was 2.2 cm (range, 1-4 cm). Twenty-six of radiofrequency ablation sessions were performed using multitined expandable electrodes. All ablations used CT guidance with moderate sedation. Adjunctive techniques used during ablation were recorded, as were instances in which ablation mandated penetration of tines beyond the kidney margin. Post-treatment ablation zones were measured from CT/MR images to evaluate serial involution and treatment response. RESULTS: Technical success in targeting and ablation was 100%. Follow-up periods ranged from 1 to 31 months (mean, 11.2). During this period, one patient presented with marginal local recurrence and underwent repeat radiofrequency ablation. Adjunctive techniques in four patients included water injection for displacement of the tail of the pancreas (n = 1) or descending colon (n = 3). Deliberate penetration of tines beyond the margins of the kidney was performed in 41% of cases; no hemorrhage occurred in these cases. No major complications occurred. Minor complications occurred in 17% of patients, including asymptomatic pneumothorax, perirenal hematomas, subcutaneous hematoma, and subcutaneous abscess. After 6 months, mean involution of the ablation zone was 15% from baseline volume per year. CONCLUSION: Multitined expandable radiofrequency electrodes produce a high rate of local control for small RCCs with a low complication rate, even when tine penetration of the kidney is required for an adequate tumor treatment margin. Adjacent organs can be protected with adjunctive percutaneous maneuvers.

Aged↗
PubMed2006

Role of ultrasound surveillance of transjugular intrahepatic portosystemic shunts in the covered stent era.

PURPOSE: To assess ultrasound (US) surveillance of expanded polytetrafluoroethylene (ePTFE)-covered stents in transjugular intrahepatic portosystemic shunts (TIPS). MATERIALS AND METHODS: Procedural data, including stent size and portosystemic gradients (PSG) before and after creation of TIPS, were obtained retrospectively in 55 patients (33 men, 22 women). Chart review provided clinical information, including etiology of liver disease, indication for TIPS creation, and Child-Pugh class. Radiology reports provided US venography data and pathology reports confirmed shunt status in transplant recipients. Patients had baseline US examinations 3-7 days after TIPS creation with scheduled follow-up at 1, 3, 6, and 12 months after the procedure. Clinical and radiology reports were compared to evaluate US surveillance of Viatorr stents. RESULTS: One hundred fifty-nine US examinations were performed on 52 patients, for an average 3.1 studies per patient (range, 1-7) over a mean follow-up duration of 173 days (range, 0-1,013 d). Sixty-four US studies (40%) were baseline studies, 88 studies (55%) were routine follow-up studies, and seven (4%) were interval studies. US predicted TIPS abnormalities in 30 of 159 studies (19%); venography followed 15 of 30 abnormal US findings (50%) and clinical examinations complemented 10 of 15 venograms (67%). Venography and US were concordant in eight of 15 paired studies (53%); clinical examinations, when conducted, accurately predicted shunt status in all but one case. US findings changed management in six of 159 studies (4%): five of six (83%) were baseline evaluations and the other one (17%) was a routine follow-up examination. A total of five baseline US examinations (8%) and one surveillance examination (1%) altered patient management. CONCLUSIONS: A single US examination after a TIPS procedure to confirm immediate function may be valuable, but routine US is not effective for long-term surveillance of ePTFE-covered stents.

Adult↗
PubMed2005

Dacron-covered stent-grafts in transjugular intrahepatic portosystemic shunts: initial experience.

PURPOSE: To retrospectively review the authors' experience with use of a Dacron-covered stent-graft in transjugular intrahepatic postosystemic shunts (TIPS). MATERIALS AND METHODS: The need for internal review board approval was waived. Informed consent was obtained from all patients. The study was compliant with the Health Insurance Portability and Accountability Act. A retrospective analysis was performed of 16 patients who received a Dacron-covered stent-graft during revision or de novo creation of TIPS. There were 13 men and three women aged 44-80 years (mean age, 61 years). Primary unassisted and assisted patency rates and secondary patency rates were estimated. The primary unassisted patency of patients who underwent de novo placement of stent-grafts (n = 10) was compared with that of patients with stent-grafts placed during shunt revision (n = 6); in all patients, stent-grafts were placed within stents. Primary unassisted patency was also compared between patients in whom the covered stent was confined to the parenchymal tract (n = 7) and those in whom the stent extended 1 cm or more into the portal vein (n = 9). Patency was estimated with the Kaplan-Meier method, and group comparisons were performed with the log-rank test. RESULTS: Primary unassisted patency rates following stent-graft placement at 4, 12, and 24 months (+/- standard error) were 64% +/- 14, 54% +/- 15, and 40% +/- 16, respectively. The rates for primary assisted patency were 78% +/- 12, 67% +/- 14, and 67% +/- 14 and those for secondary patency were 91% +/- 9, 81% +/- 12, and 54% +/- 23. At 12 months, primary unassisted patency with de novo stent-graft placement was 90% +/- 9, whereas that with stent-grafts placed during TIPS revision was 17% +/- 15 (P = .005). At 12 months, the primary unassisted patency in patients with stent-grafts confined to the parenchymal tract was 75% +/- 22, and that of patients with stent-grafts extending at least 1 cm into the portal vein was 40% +/- 17 (P = .21). CONCLUSION: In this small series, satisfactory long-term patency was observed among patients in whom Dacron-covered stent-grafts were placed during revision or de novo creation of TIPS. More favorable outcomes were observed when the stent-graft was placed during de novo TIPS creation and when the device was confined to the parenchymal tract.

Adult↗
PubMed2005

Renal artery stenosis due to fibromuscular dysplasia in an 18-week pregnant woman.

BACKGROUND: Hypertension is a frequent medical complication of pregnancy. Renovascular hypertension is present in 5-10% of cases of severe hypertension during pregnancy. CASE: In this report we describe a 36-year-old woman with severe hypertension caused by bilateral renal artery stenosis due to fibromuscular dysplasia. Guided by the patient's ultrasound findings, only 1 side was treated with angioplasty. Continued labile blood pressure resulted in arteriography of the contralateral renal artery, which confirmed renal artery stenosis was present on the other side. CONCLUSION: Clinicians should maintain a high index of suspicion for renovascular hypertension in pregnancy when drug resistance is present. Because the potential for false-negative results with noninvasive testing for renal artery stenosis is present, if clinical suspicion is high, one should consider using invasive testing.

Adult↗
PubMed2005

Renal angiomyolipoma: long-term results after arterial embolization.

PURPOSE: Selective arterial embolization of renal angiomyolipomas (AMLs) was performed to prevent hemorrhage in patients with AMLs larger than 4 cm. This study was conducted to evaluate the long-term efficacy of AML embolization. MATERIALS AND METHODS: Nineteen patients underwent embolization for 30 renal AMLs between July 1991 and June 2002. Of these, 10 patients had tuberous sclerosis (TS) with multiple AMLs and nine patients had a solitary sporadic AML. Embolization was performed with use of ethanol mixed with iodized oil (Ethiodol) in 29 tumors; coils were used in addition to the ethanol/Ethiodol mixture in one case. All tumors were completely embolized according to angiographic criteria including vascular stasis and absence of arterial feeders. The efficacy of embolization was determined over a mean follow-up period of 51.5 months (range, 6-132 months). Recurrence was defined as an increase in tumor size of greater than 2 cm on follow-up imaging and/or recurrent symptoms that required repeat embolization. An institutional review board exemption was obtained to perform this retrospective study. RESULTS: Embolization of the renal AMLs was technically successful in all 19 patients and for all 30 lesions. AML recurrence was noted in 31.6% of patients (n = 19) and for 30% of lesions overall (n = 9). Six of 10 patients in the TS group had AML recurrences. No recurrences occurred in the patients with sporadic AML. In the TS group of 10 patients, there was a total of 21 AMLs and the overall tumor recurrence rate was 42.9% (nine of 21). Six lesions in four patients had to be reembolized because of recurrent symptoms, including one hemorrhage, and three lesions in two patients required repeat embolization because of a greater than 2 cm increase in size. The median time interval from embolization to recurrence was 78.7 months (range, 13-132 months). Statistical testing with use of the Fisher exact test demonstrated that patients with TS were significantly more likely to develop recurrence than those without TS (P = .01). CONCLUSIONS: Transarterial embolization is effective in preventing hemorrhage in patients with renal AMLs. However, long-term follow-up revealed a high AML recurrence rate in patients with TS. Lifelong surveillance for recurrence after AML embolization is essential in patients with TS.

Adult↗
PubMed2005

Evaluation of a microcatheter-arterial port system for intraarterial therapy in an animal model.

A new microcatheter-arterial port system for transarterial regional therapy was evaluated in a swine model. Subclavian or femoral access was followed by superselective catheterization of target arteries (hepatic, n = 6; splenic, n = 3). A hemostatic sleeve was placed at the arterial puncture site. Implantation into the target vessel succeeded in all nine placements (100%). After animal movement, no microcatheter tip moved by more than 10 mm. A small hematoma developed at one of the subclavian insertion sites. This system holds promise for transarterial therapies for regional cancer therapy.

Animals↗
PubMed2005

Use of CT angiography to classify endoleaks after endovascular repair of abdominal aortic aneurysms.

PURPOSE: Accurate endoleak detection and classification is critical for the follow-up of patients who have undergone endovascular aneurysm repair (EVAR). This determination is often made with computed tomography angiography (CTA). This investigation was performed to determine the accuracy of CTA in the classification of endoleaks in patients who have undergone EVAR. MATERIALS AND METHODS: Thirty-six patients with endoleaks underwent both CTA and conventional contrast digital subtraction angiography (DSA) to determine endoleak etiology. Two independent radiologists determined the source of the endoleak based on a retrospective review of the CTA. The results of the CTA-based endoleak classification were compared to the reference standard, contrast DSA. RESULTS: There was agreement regarding endoleak classification between CTA and DSA on 86% of the patients (31 of 36 patients). Correlation between the CTA reading of the two readers was 94% (34 of 36 patients), yielding a kappa statistic of 0.8. In three patients, the CTA reading incorrectly classified endoleaks as type 2 when the endoleaks were actually type 1 endoleaks on DSA. One patient was incorrectly classified as having a type 1 endoleak on CTA when it was a type 2 endoleak on DSA. Finally, one patient had a type 1 endoleak on DSA that was incorrectly classified as a type 3 endoleak on CTA. The change in CTA endoleak classification based on the DSA resulted in a significant change in patient management in four of the 36 patients (11%). CONCLUSIONS: Endoleak classification based on CTA correlates fairly well with DSA findings. However, optimal endoleak management requires performance of selective angiograms with DSA to classify endoleaks that are detected on CTA.

Angiography↗
PubMed2005

Embolization of type 2 endoleaks after endovascular repair of abdominal aortic aneurysms with use of cyanoacrylate with or without coils.

Translumbar embolization was used to treat 11 type 2 endoleaks in nine patients with the liquid embolic agent n-butyl cyanoacrylate (NBCA). Nine of the embolizations were performed with a combination of stainless-steel coils and NBCAJ and the other two were performed with NBCA alone. There was complete occlusion on initial computed tomographic (CT) angiography in six of nine patients (66%), including the two cases treated with NBCA alone. Persistent endoleak on initial CT angiography occurred in three of nine patients (33%). Two of these patients underwent successful repeated embolization with NBCA. Aneurysm size remained unchanged in four patients (44%), decreased in four patients (44%), and increased in one patient (11%). No complications occurred. Initial results with the use of NBCA for endoleak embolization are encouraging.

Aged↗
PubMed2005

Experience with the recovery filter as a retrievable inferior vena cava filter.

PURPOSE: This study evaluates clinical experience with the Recovery filter as a retrievable inferior vena cava (IVC) filter. MATERIALS AND METHODS: One hundred seven Recovery filters were placed in 106 patients with an initial clinical indication for temporary caval filtration. Patients were followed up to assess filter efficacy, complications, eventual need for filter removal, time to retrieval, and ability to remove the filter. RESULTS: The patient cohort consisted of 62 men and 44 women with a mean age of 48 years (range, 18-90 y). Mean implantation time was 165 days. Indications for filter placement in patients with deep vein thrombosis (DVT) and/or pulmonary embolism (PE) included contraindication to anticoagulation (n = 33), complications of anticoagulation (n = 8), poor cardiopulmonary reserve (n = 6), large clot burden (n = 3), and PE while receiving anticoagulation (n = 1). Indications for filter placement in patients without proven PE or DVT included immobility after trauma (n = 35); recent intracranial hemorrhage, neurosurgery, or brain tumor (n = 18); and other surgical or invasive procedure (n = 3). Three patients (2.8%) had symptomatic PE after placement of the Recovery filter. No caval thromboses were detected. No symptomatic filter migrations occurred. Recovery filter removal was attempted in 15 of 106 patients (14%) at a mean of 150 days after placement. The Recovery filter was successfully retrieved in 14 of 15 patients (93%); one removal was unsuccessful at 210 days after placement. Ninety-two filters (87%) currently remain in place. CONCLUSIONS: Although all the filters were placed with the intention of being removed, a large percentage of filters were not retrieved. The Recovery filter was safe and effective in preventing PE when used as a retrievable IVC filter.

Adolescent↗
PubMed2005

Recurrent endoleak detection and measurement of aneurysm size with CTA after coil embolization of endoleaks.

PURPOSE: The optimal modality for following aneurysm size and detecting endoleaks after endovascular aneurysm repair (EVAR) remains controversial. Computed tomographic angiography (CTA) has been widely employed but can be limited by metal artifact from stents, which is exacerbated by embolization coils placed during the treatment of type 2 endoleaks. The authors assessed interobserver agreement of CTA for measuring aneurysm size and presence of recurrent endoleak in patients with prior coil embolization of type 2 endoleaks. MATERIALS AND METHODS: A total of 65 CTAs were retrospectively reviewed in a cohort of 27 patients (25 men; two women; mean age, 77.4 years) who had prior endoleak embolization after EVAR. Endoleak embolizations included transarterial (n=8) and translumbar (n=19) approaches. In each patient, maximal aneurysm diameter and presence/absence of recurrent endoleak was measured independently by two observers. Cohen's Kappa statistic was used to assess interobserver agreement, as well as paired two-tailed Student t tests for aneurysm diameter. RESULTS: Recurrent type 2 endoleaks were detected with CTA in eight of 27 patients (30%) and on 13 of 65 CTAs (20%). A high degree of correlation (98.5%) was also seen between the two observers for presence of endoleak (Kappa=0.95). Mean aneurysm diameter for the entire cohort correlated closely between both observers: 54.8 mm+/-1.1 for observer A and 54.9 mm+/-1.1 for observer B (P=.66). There was a disagreement between the readers of greater than 2 mm regarding aneurysm size in 13.8% of the CTAs (nine of 65 CTAs). CONCLUSION: Despite the presence of streak artifact on CTA following coil embolization of type 2 endoleaks, CTA remains a useful study for following patients. The presence of embolization coils does not prevent CTA measurement of aneurysm diameter and detection of recurrent endoleak with a high degree of interobserver agreement.

Aged↗
PubMed2005

Single-center experience with the Arrow-Trerotola Percutaneous Thrombectomy Device in the management of thrombosed native dialysis fistulas.

PURPOSE: The present study sought to evaluate the performance of the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) in the treatment of native fistula thrombosis in a U. S. hemodialysis population. Specifically, the technical success, clinical success, complication rate and type, primary and secondary patency rates, effect of adjunctive thrombolytic therapy, and any variables that affected outcomes of procedures in which this device was used were analyzed. MATERIALS AND METHODS: Forty-two patients with 44 thrombosed native fistulas (17 radiocephalic, 10 brachiocephalic, 10 transposed or superficialized, five graft/fistula hybrids, and two leg fistulas) were treated with 62 mechanical thrombolysis procedures with use of the PTD. All patients had large clot burden. The device type was recorded in 43 procedures: standard (n = 21), over-the-wire (OTW; n = 19), or both (n = 3). No device was used in two cases because of inability to cross the anastomosis. Adjunctive therapies (n = 18) included the use of tissue plasminogen activator (tPA; n = 16) and deployment of the AngioJet device with (n = 1) or without tPA (n = 1). Stents were inserted in four procedures. Outcome variables included technical and clinical success, complications, and primary and secondary patency. Cox proportional-hazards regression and Kaplan-Meier analyses were performed. RESULTS: The technical success rate was 87% (54 of 62) and the clinical success rate was 79% (49 of 62). Percutaneous transluminal angioplasty was performed in all but two procedures. Complications occurred in 13% of procedures (n = 8); three resulted in technical failure. The primary patency rates were 38% at 6 months and 18% at 12 months; secondary patency rates were 74% and 69%, respectively. Outcomes were not affected by adjunctive techniques, fistula type, age of fistula, device type (ie, OTW vs standard), or patient sex. Secondary patency was superior when no residual clot or stenosis was present (P = .003). CONCLUSIONS: The PTD is effective for percutaneous treatment of thrombosed hemodialysis fistulas, with good short- and long-term outcomes in a U.S. population. Within the limitations of a retrospective study with a small sample size, use of an adjunctive thrombolytic agent did not appear to improve results compared with the use of the device alone.

Adult↗
PubMed2005

Prospective study of balloon inflation pressures and other technical aspects of hemodialysis access angioplasty.

PURPOSE: Balloon angioplasty is a mainstay in the treatment of failing or thrombosed hemodialysis access grafts and fistulas. A sizable body of outcomes data exists concerning percutaneous transluminal angioplasty (PTA) in hemodialysis access, yet there is a relative paucity of technical information available, especially regarding dilation pressures. The aim of the present study was to compile such information, which can be critical to the choice of devices for PTA and to the design of future clinical trials seeking to improve outcomes in this area. MATERIALS AND METHODS: Technical data were collected prospectively for 102 PTA procedures (66 prophylactic PTA procedures and 36 PTA procedures performed during access thrombectomy). Demographic data concerning the access were collected. Technical data were collected individually for each lesion treated, including lesion location; degree of stenosis (in quartiles); lesion length; PTA balloon brand, size, and length; pressure at which the waist of the balloon was effaced; residual stenosis; and reason for additional balloons or inflations if used. Outcomes data other than residual stenosis were not collected, but the endpoint for all interventions was a thrill in the access. RESULTS: A total of 230 lesions were treated. Two (1%) could not be successfully treated with PTA despite the use of "ultra high" pressure (approximately 40 atm); one was treated successfully with parallel wire technique and the other was revised surgically after the use of a cutting balloon also failed. Overall, 55% of lesions required pressures greater than 15 atm to efface the waist. Excluding initial failures, 20% of lesions in native fistulas and 9% in grafts required very high pressure (>20 atm) to efface the waist (P = .02). High pressure was needed less frequently in PTA procedures performed in the setting of thrombectomy procedures than in prophylactic PTA procedures (P = .0001). Residual stenosis was positively correlated with severity of initial stenosis and negatively correlated with duration of inflation. CONCLUSIONS: Conventional angioplasty balloons are inadequate for the treatment of most hemodialysis access stenoses. High pressures (>15 atm) are commonly needed for PTA in hemodialysis access. Very high pressures (>20 atm) are more frequently needed in native fistulas.

Angioplasty, Balloon↗
PubMed2004

Quality improvement guidelines for uterine artery embolization for symptomatic leiomyomata.

Uterine artery embolization (UAE) is assuming an important role in the treatment of women with symptomatic uterine leiomyomata worldwide. The following guidelines, which have been jointly published with the Society of Interventional Radiology in the Journal of Vascular and Interventional Radiology, are intended to ensure the safe practice of UAE by identifying the elements of appropriate patient selection, anticipated outcomes, and recognition of possible complications and their timely address.

Embolization, Therapeutic↗