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Timothy W I Clark

Publications and source records attributed to Timothy W I Clark.

At least 37 records · Page 2Linked to original sources
PubMed2004

Embolization of traumatic pseudoaneurysms after total knee arthroplasty.

We report on 2 cases of traumatic pseudoaneurysm after total knee arthroplasty. In one patient, a hemarthrosis and a pulsatile antecubital mass developed 1 month after arthroplasty, prompting angiography. In the second patient, evacuation of a large hemarthrosis was performed before angiography and embolization. In both patients, the pseudoaneurysm was successfully treated without the need for surgical repair, using percutaneous thrombin injection or transcatheter embolization. No recurrence of hemarthrosis was seen in either patient at up to 24 months of follow-up evaluation. These cases show the use of angiography in reconstructed joints when acute or delayed hemarthrosis occurs, and the role of embolization techniques in this setting.

Aged↗
PubMed2004

Do simultaneous bilateral tunneled infusion catheters in patients undergoing bone marrow transplantation increase catheter-related complications?

PURPOSE: Secure venous access with multiple lumens is necessary for the care of allogeneic hematopoietic stem cell transplant (HSCT) recipients. The outcomes associated with simultaneous bilateral tunneled internal jugular infusion catheter placement in the HSCT recipient population were investigated in an attempt to determine whether simultaneous introduction of these catheters compounds or magnifies the risks (infection, venous thrombosis) associated with tunneled catheters. MATERIALS AND METHODS: Patients undergoing HSCT and receiving bilateral tunneled infusion catheters in a single procedure were identified using a quality assurance data base. Medical records for the duration of catheterization were reviewed; 43 patients were included in the study (mean age, 42 years; range, 22-56). Diagnoses included acute lymphocytic leukemia (n = 4), acute myelogenous leukemia (n = 8), aplastic anemia (n = 2), chronic myelogenous leukemia (n = 17), chronic lymphocytic leukemia (n = 1), Hodgkin lymphoma (n = 1), myelodysplasia (n = 4), myelofibrosis (n = 2), and non-Hodgkin lymphoma (n = 4). Cox proportional hazards regression analysis was performed to determine differences in infection rates between dual- and triple-lumen catheters. RESULTS: Forty-three pairs of catheters were placed. All met venous access needs for HSCT recipient care. Complete follow-up was achieved for 77 of 87 (89%) catheters. The overall infection rate was 0.25 per 100 catheter-days. The rate was 0.19 and 0.33 for dual- and triple-lumen catheters, respectively (P =.15). Mechanical failure did not differ between catheter types (dual: 0.14 episodes per 100 days, triple: 0.05 per 100 days, P =.2). CONCLUSIONS: Bilateral multilumen tunneled infusion catheter placement in a single procedure using imaging guidance is safe with acceptable outcomes and meets venous access needs for HSCT. There is a trend toward higher infection rates, with more lumens and more mechanical failure with dual-lumen catheters.

Adult↗
PubMed2004

Percutaneous ablation of VX2 carcinoma-induced liver tumors with use of ethanol versus acetic acid: pilot study in a rabbit model.

PURPOSE: Acetic acid has been employed as a chemical ablation agent for liver tumors because of its superior diffusion characteristics compared with ethanol and the resulting requirement for smaller volumes and fewer injection sessions. Early tissue changes were compared after injection of acetic acid and ethanol in a rabbit model of hepatocellular carcinoma. MATERIALS AND METHODS: VX2 tumors were created in the left lobe of the liver in 11 male New Zealand White rabbits. Each animal underwent a midline minilaparotomy to expose the tumor-laden left lobe, followed by injection of 1.0 mL of 100% ethanol (n = 5) or 50% acetic acid (n = 6) with use of a 20-gauge infusion needle. Animals were killed 30 minutes after surgery; explanted livers were sectioned and examined for gross and microscopic changes. RESULTS: Injection of each agent produced rapid diffusion through tumor and surrounding hepatic parenchyma, with immediate protein precipitation manifested by blanching as a result of coagulation effect. The sizes of coagulation zones, expressed as mean products of the maximum perpendicular diameters of tumoral diffusion, were 13.0 cm(2) +/- 9.4 and 1.3 cm(2) +/- 1.8 for acetic acid and ethanol, respectively (P =.049). No differences in histologic changes were seen between agents. CONCLUSIONS: In this animal model, acetic acid produced significantly larger zones of tumor coagulation compared with ethanol when injected into VX2 carcinoma in equal volumes. Further evaluation is necessary before these findings can be extrapolated to a clinical setting.

Acetic Acid↗
PubMed2004

The effect of initial shunt outflow position on patency of transjugular intrahepatic portosystemic shunts.

PURPOSE: It has been suggested that initial stent position in transjugular intrahepatic portosystemic shunts (TIPS) with relation to hepatic venous outflow is an important determinant of shunt patency. It was hypothesized that TIPS with the stent-implanted segments terminating in the hepatic vein (HV) have shorter primary unassisted shunt patency durations than TIPS with the stent-implanted segments extending to the hepatocaval junction. MATERIALS AND METHODS: A consecutive group of 107 patients who underwent TIPS creation for variceal bleeding were retrospectively identified, and the angiographic images during initial TIPS creation were reviewed independently by two observers who were blinded to outcome. Primary unassisted patency was estimated in group A (TIPS terminating in the HV; n = 47) and group B (TIPS terminating at the hepatocaval junction; n = 60) with the Kaplan-Meier method, and the two groups were compared with the log-rank test. Patients who had less than 30 days of follow-up were excluded from the analysis. RESULTS: Among all 107 patients, primary unassisted patency rates at 3, 6, and 12 months were 91% +/- 4%, 74% +/- 6%, and 49% +/- 6%. TIPS were classified into group A or group B with high interobserver agreement (Cohen kappa = 0.98). At 12 months, the primary unassisted patency rate among the patients in group A was 36% +/- 10%, compared with 58% +/- 8% among the patients in group B (P =.017, log-rank test). Patients in group A were twice as likely to lose patency than patients in group B (95% CI of odds ratio, 1.2-4.5). Thirty-day mortality was similar between groups (15% vs 12%; P =.13). CONCLUSION: Initial stent position within the hepatic venous outflow is predictive of shunt patency, with TIPS extending to the hepatocaval junction having a longer lifespan than shunts terminating in the HV.

Case-Control Studies↗
PubMed2004

Relationship between chest port catheter tip position and port malfunction after interventional radiologic placement.

PURPOSE: The relationship between catheter tip position of implanted subcutaneous chest ports and subsequent port malfunction was investigated. Tip movement from initial supine position to subsequent erect position was also evaluated. MATERIALS AND METHODS: Patients who underwent imaging-guided internal jugular chest port placement between July 2001 and May 2003 were identified with use of a quality-assurance database. Sixty-two patients were included in the study (22 men and 40 women), with a mean age of 58 years (range, 27-81 years). Catheter tip location on the intraprocedural chest radiograph was determined with use of two methods. First, the distance from the right tracheobronchial angle (TBA) was recorded (TBA distance). Second, tip location was classified into six anatomic regions: 1, internal jugular veins; 2, brachiocephalic veins; 3, superior vena cava (SVC; n = 11); 4, SVC/right atrial junction (n = 22); 5, upper half of right atrium (n = 25); and 6, lower half of right atrium (n = 4). For the duration of follow-up, catheter tip location was documented, as were all episodes of catheter malfunction. RESULTS: Patients with catheter tips initially placed in position 3 had a higher risk of port malfunction (four of 11; 36%) than patients with catheter tips located in position 5 (two of 25; 8%). This difference narrowly fell short of statistical significance (P =.057). When comparing intraprocedural chest radiographs to the first erect chest radiographs, significant upward tip movement was noted. The tips migrated cephalad an average of 20 mm (P =.003) and 1.0 position units (P =.001). DISCUSSION: Catheter tips placed in the SVC tended to have a greater risk of port malfunction compared with those positioned in the right atrium. Chest ports migrated cephalad between the supine and erect positions.

Adult↗
PubMed2004

Measurement of portal blood and transjugular intrahepatic portosystemic shunt flow with use of a retrograde thermodilutional catheter.

PURPOSE: Direct blood flow measurement in the portal vein (PV) and in transjugular intrahepatic portosystemic shunts (TIPS) holds potential as a means of optimizing shunt creation and predicting outcomes. A retrograde thermodilutional flow measurement catheter was recently designed. The purpose of this study was to validate and optimize the technique of blood flow measurement in the PV with use of this catheter in a swine model of TIPS. MATERIALS AND METHODS: Six domestic swine underwent TIPS creation. At day 14, shunts were catheterized for venography and portal blood flow measurement with use of thermodilutional catheters. Simultaneous flow measurements were made with use of the thermodilutional and perivascular methods at the same anatomic location within the PV. To test reproducibility of the flow measurement, repeated measurements were performed in the PV and shunt. RESULTS: Fifty-five measurements of PV blood flow with the thermodilutional catheter and perivascular probe were made in five animals. Perivascular probe placement was unsuccessful in one animal. There was high correlation between the thermodilutional and perivascular measurements (r(2) = 0.96; Q(periv) = 0.80 . Q(therm) + 147 mL/min; n = 55; range, 205-1541 mL/min). The difference between two consecutive thermodilutional measurements and their mean was less than 50 mL/min in 72% of measurements and less than 100 mL/min in 94% of measurements (N = 85 pairs). CONCLUSIONS: Measurement of PV blood flow with use of a retrograde thermodilutional catheter system yields reliable and reproducible results. This catheter system holds promising utility as a device for measuring flow within TIPS and the PV.

Animals↗
PubMed2004

Risk of intrauterine infectious complications after uterine artery embolization.

PURPOSE: To identify risk factors for the development of intrauterine infection following uterine artery embolization. MATERIALS AND METHODS: A retrospective review of uterine artery embolizations (UAE) performed for the treatment of symptomatic fibroids from January 2000 to July 2003 was conducted. With logistic regression and the Fisher exact test, multiple variables were analyzed as predictors for intrauterine infectious complications requiring medical and/or surgical therapy, including the use of preprocedural antibiotics, embolic agent used, quantity of embolic material, location of fibroids (submucosal, nonsubmucosal), and size and location of the dominant fibroid. RESULTS: A total of 414 UAE procedures were performed in 410 patients with a technical success rate of 99%. Average age of the patient cohort was 42.8 years (SD, 5.8 years). One hundred forty-eight patients (36.1%) had submucosal fibroids or fibroids projecting submucosally, 262 patients (63.9%) had nonsubmucosal fibroids. Intrauterine infectious complications requiring intravenous antibiotic therapy and/or surgery occurred in five patients (1.2%). A total of five infectious complications requiring therapy occurred in the submucosal group (3.4%) and none in the nonsubmucosal group. Patients within the submucosal group were more likely to develop intrauterine infectious complications than patients with nonsubmucosal fibroids based on univariate analysis (P = .006) but with logistic regression, the association was not significant (P = .079). No significant difference with embolic agent, quantity of embolic particles, use of preprocedure antibiotics, or size of or location of the dominant fibroid was found. CONCLUSION: No specific risk factor for intrauterine infection following UAE was identified in this study. Infection after UAE is rare and appears to be a sporadic occurrence. Nevertheless, close surveillance is warranted in all women following UAE given the potential morbidity of this complication.

Adult↗
PubMed2004

Transplant renal artery stenosis: outcome after percutaneous intervention.

PURPOSE: To assess the outcome of percutaneous transluminal angioplasty (PTA) and stent placement as the primary treatment for transplant renal artery stenosis (TRAS). MATERIALS AND METHODS: A retrospective review of PTA and stent placement procedures performed for TRAS from April 1997 to July 2003 was conducted. Reviewed parameters included technical success, date of transplantation, dates of percutaneous intervention, mean arterial blood pressure, number of blood pressure medications, and serum creatinine level before and after intervention. Twenty-one interventions were performed in 18 allografts. The primary clinical indication for imaging and treatment was increased creatinine level in 12 allografts and hypertension in six allografts. Patency rates were estimated with use of the Kaplan-Meier method. RESULTS: The technical success rate of PTA/stent placement was 100% and the clinical success rate was 94% (17 of 18 allografts). Thirteen interventions involved PTA alone, with eight combined PTA and stent insertions. The mean preintervention serum creatinine level among 12 allografts presenting with elevated creatinine levels was 2.8 mg/dL +/- 1.4 (SD), compared with a 1-month postintervention mean of 2.2 mg/dL +/- 0.7 (P = .03). Of six allografts that presented with hypertension, significant improvement was seen between the preintervention and 1-month postintervention mean systolic (174 mm Hg vs 135 mm Hg, P = .003) and diastolic (99 mm Hg vs 82 mm Hg, P = .02) pressures. These patients required a mean of 2.3 medications for blood pressure control before intervention, compared with a mean of 1.0 medications at 1 month after intervention (P = .002). Primary patency rates at 3, 6, and 12 months (+/-95% CI) were 94% +/- 6%, 72% +/- 12%, and 72% +/- 12%, respectively. Secondary patency rates at 3, 6, and 12 months (+/-95 CI) were 100%, 85% +/- 10%, and 85% +/- 10%, respectively. Mean follow-up time was 27 months. Of the eight allografts that underwent stent placement, all eight remained patent at last follow-up (mean, 18.3 months +/- 9.2). One major complication of a puncture site pseudoaneurysm occurred (5%). CONCLUSION: Primary treatment of TRAS with PTA with or without stent placement has good intermediate-term patency and is associated with significant early improvement in blood pressure and creatinine level.

Adult↗
PubMed2003

The Woggle technique for suture closure of hemodialysis access catheterization sites.

The Woggle technique is a modification of the purse-string suture technique, which is used to achieve hemostasis at hemodialysis catheterization sites. A tension collar (plastic guide wire introducer or similar device) is placed over the ends of a purse-string suture and secured with a suture lock (hemostat or stopcock) to tighten the suture without making a knot. The device is left in place for 20 to 60 minutes after the sheath is removed and then the woggle device is released and, if hemostasis is achieved, the suture is removed. This technique allows the patient to be discharged without a suture in place.

Adult↗
PubMed2003

Percutaneous chemical ablation of desmoid tumors.

Desmoid tumors are rare fibroblastic neoplasms characterized by highly aggressive local invasion and high recurrence rates after surgical excision. Responses to chemotherapy and radiation therapy are uncommon. The use of percutaneous chemical ablation performed under imaging guidance is described in two patients with recurrent and/or unresectable disease. A complete response was achieved in one patient and a partial response was achieved in the other patient; these responses were sustained during 2 years of follow-up. This technique may hold promise in the treatment of these challenging lesions.

Acetic Acid↗
PubMed2003

Prevalence and treatment of cephalic arch stenosis in dysfunctional autogenous hemodialysis fistulas.

PURPOSE: Cephalic arch stenosis (CAS) is a recently recognized cause of dysfunction in autogenous hemodialysis fistulas. The prevalence of this lesion among dysfunctional autogenous fistulas is described, as are outcomes after percutaneous therapy. MATERIALS AND METHODS: A cohort of 177 dysfunctional autogenous fistulas treated over a 48-month period was retrospectively analyzed for the presence of CAS. Of these, 116 (66%) were radiocephalic fistulas and 61 (34%) were brachiocephalic fistulas. CAS was identified in 26 fistulas among 24 patients. Fifty dilations and three stent placements in the cephalic arch were performed. Surveillance was conducted after percutaneous therapy by means of ultrasound dilution technique and measurement of dialysis flow rates. Patency rates were estimated with use of the Kaplan-Meier method. No patients were lost to follow-up. RESULTS: The prevalence of CAS was 15% (26 of 177). There was a significant difference in the prevalence of CAS between brachiocephalic and radiocephalic fistulas (39% vs 2%; P <.001). High-pressure noncompliant balloon catheters were required in 29 of 50 dilations (58%) to efface the lesion. Primary patency rates (+/-SE) at 3, 6, and 12 months were 76% +/- 8, 42% +/- 10, and 23% +/- 9, respectively. Primary assisted patency rates (+/-SE) at 3, 6, and 12 months were 96% +/- 4, 83% +/- 8, and 75% +/- 10. Complications occurred in three cases (6%). A major complication with rupture of the cephalic arch resulted in thrombosis and fistula loss (n = 1); two minor complications of cephalic arch rupture were salvaged with placement of a Wallstent (n = 1) or prolonged balloon inflation (n = 1). CONCLUSIONS: CAS is common among failing brachiocephalic arteriovenous fistulas. With aggressive percutaneous intervention and surveillance, favorable primary assisted patency rates can be achieved.

Aged↗
PubMed2003

Treatment of obstructive nephroureteral clot with a rheolytic mechanical thrombectomy device.

Thrombus within the renal collecting system and ureter after percutaneous intervention is usually self-limited, but when it is obstructive enough to produce anuria, it can cause deterioration of renal function. Herein a case of a patient with a transplant kidney in whom clot anuria developed after conversion of a nephroureteral stent to a nephrostomy catheter is presented. Internal urine drainage was restored with the use of a rheolytic mechanical thrombectomy device, with subsequent return of normal renal function.

Humans↗
PubMed2003

Percutaneous transhepatic venous access for hemodialysis.

Percutaneous transhepatic venous access is an option for hemodialysis patients who have exhausted more traditional sites of venous access. Thirty-six transhepatic dialysis catheters were placed in 12 patients. The mean time of the catheters in situ was 24.3 days. Twenty-one catheters were replaced or removed because of catheter thrombosis, yielding a catheter thrombosis rate of 2.40 per 100 catheter-days. The line sepsis rate was 0.22 per 100 catheter-days. Poor patency rates were seen because of a high rate of late thrombosis. Transhepatic dialysis catheters should only be used as a last resort unless limitations of catheter thrombosis can be overcome.

Adult↗
PubMed2003

Physical examination versus normalized pressure ratio for predicting outcomes of hemodialysis access interventions.

PURPOSE: The ratio of intragraft venous limb pressure (VLP) to systemic pressure (S) has been proposed to help determine the endpoint of hemodialysis access interventions. It was hypothesized that physical examination of the access could be used in the same way and these techniques were compared as predictors of outcome. PATIENTS AND METHODS: With use of a quality-assurance database, records from 117 hemodialysis access interventions were retrospectively reviewed. Only interventions in grafts were included. The database included physical examination (to establish thrill, thrill with slight pulsatility [TSP], pulse with slight thrill [PST], and pulse) at three locations along the graft (proximal, midportion, and distal), normalized pressure ratio calculated with S from a blood pressure cuff (S(cuff)) and S within the graft with outflow occluded (S(direct)), graft configuration and location, indication, operator, and time to next intervention (outcome of primary patency). Only procedures with complete follow-up data were included in the analysis (n = 97; declotting, n = 51; prophylactic percutaneous transluminal angioplasty [PTA], n = 46). Statistical analysis was performed with use of Cox proportional-hazards regression. RESULTS: Graft configuration, location, side, VLP, S(direct), and S(cuff) did not affect outcomes. An operator effect was noted for two physicians and was adjusted for in all analyses. Pressure ratios were weak predictors of outcome (VLP/S(direct), P =.07; VLP/S(cuff), P =.08) and suggested that patency increased with increasing pressure ratio, contrary to earlier studies. Procedure type predicted outcome (declotting, median patency of 50 days; PTA, median patency of 105 days; P =.01). Thrill at distal physical examination was predictive of outcome (P =.04) and even more so when thrill and TSP combined were compared with PST and pulse combined (P =.03). Similar but less-pronounced effects were seen at midportion and proximal physical examinations. CONCLUSIONS: The presence of a thrill or slightly pulsatile thrill at the distal (venous) end of a dialysis graft is the best predictor of outcome after percutaneous intervention. Based on the present study, the authors believe that physical examination of dialysis access should supplant pressure measurements as an endpoint of intervention and should serve as an essential component of quality assurance of access interventions.

Arteriovenous Shunt, Surgical↗
PubMed2003

Use of abciximab during infrainguinal peripheral vascular interventions: initial experience.

PURPOSE: To investigate the use of abciximab as an adjunct during infrainguinal angioplasty. MATERIALS AND METHODS: Abciximab was used in conjunction with recanalization techniques and angioplasty to treat stenoses or occlusions in 16 patients: 10 patients had high-grade stenoses or occlusions longer than 5 cm in the superficial femoral artery and popliteal artery, and six patients had stenoses or occlusions below the popliteal artery. All patients received a bolus of heparin after arterial access was achieved. Abciximab was administered by means of a weight-base nomogram that consisted of an initial bolus followed by an overnight infusion. Technical success was defined as a less than 30% residual stenosis after angioplasty. Patients were carefully followed up for possible postprocedural complications. Platelet counts were monitored for 24 hours. RESULTS: Technical success was achieved in 15 (94%) of 16 patients. One occlusion of the superficial femoral artery could not be crossed. There was a mean postprocedural increase of 0.23 in the ankle-brachial index. There was no significant effect on platelet count. Two minor complications occurred. One major complication occurred; this was a groin hematoma, which required a blood transfusion. CONCLUSION: The use of abciximab as an adjunct during complex infrainguinal arterial interventions appears promising, on the basis of initial experience.

Abciximab↗