Bjorn I. Engstrom

Analysis of Infection Risk following Covered Stent Exclusion of Pseudoaneurysms in Prosthetic Arteriovenous Hemodialysis Access Grafts

PURPOSE To determine whether exclusion of pseudoaneurysms with the use of a covered stent in prosthetic arteriovenous (AV) hemodialysis access grafts impacts the incidence of eventual AV graft infection. MATERIALS AND METHODS Review of an interventional radiology database for prosthetic AV graft interventions involving stent deployment anywhere within the AV graft circuit revealed 235 interventions in 174 patients between November 2004 and December 2008. Incidence of AV graft infection was analyzed based on stent type (bare metal vs covered), location, and indication for stent deployment on a per-stent, per-procedure, and per-graft basis. RESULTS A total of 16.3% of the stent-implanted AV grafts were eventually surgically excised as a result of graft infection. Covered stents used to treat an intragraft pseudoaneurysm were more commonly associated with subsequent graft infection compared with bare or covered stents deployed within the graft for other reasons: 42.1% versus 18.2% (P = .011). Stents deployed in an intragraft location were also associated with a higher incidence of graft infection compared with those deployed at the venous anastomosis or outflow vein: 26.9% versus 6.9% (P < .001). No significant difference was identified in infection rates between bare and covered stents. CONCLUSIONS Covered stent exclusion of intragraft pseudoaneurysms demonstrated a significant correlation with eventual prosthetic AV graft infection.

Incidental detection of nutcracker phenomenon on multidetector CT in an asymptomatic population: prevalence and associated findings.

Objective To determine the prevalence of nutcracker phenomenon (left renal vein compression by the superior mesenteric artery) and secondary anatomic findings using multidetector computed tomographic (CT) angiography in an asymptomatic population. Methods Ninety-nine consecutive CT angiograms for potential renal transplant donors (mean age, 39.0 years; 42 males) without variant renal vein anatomy were reviewed retrospectively. The diameters of the maximal left renal vein, left renal vein between the aorta and superior mesenteric artery, and draining gonadal and lumbar veins were measured. Sex, age, hematuria, proteinuria, and abdominal or flank pain were recorded. Results Twenty-three patients had 50% to 70% stenosis, and 4 patients had greater than 70% stenosis of the left renal vein. Dilated gonadal and lumbar veins were found in 16 and 28 patients, respectively. Four patients had hematuria. These findings were not significantly associated with left renal vein compression. Conclusions Nutcracker phenomenon and dilated veins originating from the left renal vein are common incidental CT findings and nonspecific for the diagnosis of nutcracker syndrome.

Tunneled Internal Jugular Hemodialysis Catheters: Impact of Laterality and Tip Position on Catheter Dysfunction and Infection Rates

PURPOSE To determine rates of dysfunction and infection for tunneled internal jugular vein hemodialysis catheters based on laterality of insertion and catheter tip position. MATERIALS AND METHODS Retrospective review of a procedural database for tunneled internal jugular vein hemodialysis catheter placements between January 2008 and December 2009 revealed 532 catheter insertions in 409 patients (234 male; mean age, 54.9 y). Of these, 398 catheters were placed on the right and 134 on the left. The catheter tip location was categorized as superior vena cava (SVC), pericavoatrial junction, or mid- to deep right atrium based on review of the final intraprocedural radiograph. The rates of catheter dysfunction and catheter-related infection (reported as events per 100 catheter-days) were analyzed. RESULTS Catheters terminating in the SVC or pericavoatrial junction inserted from the left showed significantly higher rates of infection (0.50 vs 0.27; P = .005) and dysfunction (0.25 vs 0.11; P = .036) compared with those inserted from the right. No difference was identified based on laterality for catheter tip position in the mid- to deep right atrium. Left-sided catheters terminating in the SVC or pericavoatrial junction had significantly more episodes of catheter dysfunction or infection than catheters terminating in the mid- to deep right atrium (0.84 vs 0.35; P = .006), whereas no significant difference was identified for right-sided catheters based on tip position. CONCLUSIONS When inserted from the left internal jugular vein, catheter tip position demonstrated a significant impact on catheter-related dysfunction and infection; this relationship was not demonstrated for right-sided catheters.

Comparison of Primary Jejunostomy Tubes versus Gastrojejunostomy Tubes for Percutaneous Enteral Nutrition

PURPOSE To evaluate technical success and long-term outcomes of percutaneous primary jejunostomy tubes for postpyloric enteral feeding compared with percutaneous gastrojejunostomy (GJ) tubes. MATERIALS AND METHODS Over a 25-month interval, 41 consecutive patients (26 male; mean age, 55.9 y) underwent attempted fluoroscopy-guided direct percutaneous jejunostomy tube insertion. Insertions at previous jejunostomy tube sites were excluded. The comparison group consisted of all primary GJ tube insertions performed over a 12-month interval concomitant with the jejunostomy tube interval (N = 169; 105 male; mean age, 59.4 y). Procedural, radiologic, and clinical data were retrospectively reviewed. Intervention rates were expressed as events per 100 catheter-days. RESULTS The technical success rate for percutaneous jejunostomy tube insertion was 96%, versus 93% for GJ tubes (P = .47). Mean fluoroscopy times were similar for jejunostomy and GJ tubes (9.8 vs 10.0 min, respectively; P value not significant). Jejunostomy tubes exhibited a lower rate of catheter dysfunction than GJ tubes, with catheter exchange rates of 0.24 versus 0.93, respectively, per 100 catheter-days (P = .045). GJ tube tip retraction into the stomach occurred in 9.5% of cases, at a rate of 0.21 per 100 catheter-days. Intervention rates related to leakage were 0.19 and 0.03 for jejunostomy and GJ tubes, respectively (P < .01). Jejunostomy and GJ tubes exhibited similar rates of catheter exchange for occlusion and replacement as a result of inadvertent removal. No major complications were encountered in either group. CONCLUSIONS Percutaneous insertion of primary jejunostomy tubes demonstrated technical success and complication rates similar to those of GJ tubes. Jejunostomy tubes exhibited a lower dysfunction rate but a higher leakage rate compared with GJ tubes.

Management of Dysfunctional Catheters and Tubes Inserted by Interventional Radiology

Minimally invasive percutaneous interventions are often used for enteral nutrition, biliary and urinary diversion, intra-abdominal fluid collection drainage, and central venous access. In most cases, radiologic and endoscopic placement of catheters and tubes has replaced the comparable surgical alternative. As experience with catheters and tubes grows, it becomes increasingly evident that the interventional radiologist needs to be an expert not only on device placement but also on device management. Tube dysfunction represents the most common complication requiring repeat intervention, which can be distressing for patients and other health care professionals. This manuscript addresses the etiologies and solutions to leaking and obstructed feeding tubes, percutaneous biliary drains, percutaneous catheter nephrostomies, and drainage catheters, including abscess drains. In addition, we will address the obstructed central venous catheter.

Impact of phase of respiration on central venous catheter tip position

Purpose To determine the impact of the phase of respiration on CVC tip position using cross-sectional imaging. Methods We retrospectively analyzed the CT scans of 24 consecutive patients (eight men and 16 women, mean age 56.3 years, range 18-79) who underwent a CT scan protocol that includes both imaging of the thorax in inspiration and expiration. Only patients with a central venous catheter and absence of any substantial pulmonary pathology that might affect lung volumes were included. Measurements of the catheter tip location and central venous structures were obtained from inspiratory and expiratory phase images in each patient and compared using the paired t test. Results The length of the SVC and superior mediastinum were significantly longer during inspiration compared to expiration (9 mm and 7 mm respectively, P<0.001 for both). The distance between the superior and inferior cavo-atrial junction did not change significantly with respiration. The catheter tip location moved on average 9 mm (range 0-25 mm) cephalad during inspiration compared to expiration (P=0.001) in relation to the superior cavoatrial junction. The amount of catheter tip movement correlated significantly with the degree of diaphragmatic excursion with respiration (R=0.58). During inspiration, the cavo-atrial junction was on average 11 mm inferior to the right cardiomediastinal angle observed on radiography, but was nearly identical during expiration (R=0.78, P<0.001). Conclusions The central catheter tip position varied significantly with respiratory motion, with a mean excursion of 9 mm. The right cardiomediastinal border demonstrated a strong correlation with the actual location of the superior cavo-atrial junction in expiration, but not in inspiration.

Accessory Veins in Nonmaturing Autogenous Arteriovenous Fistulae: Analysis of Anatomic Features and Impact on Fistula Maturation

The appropriate management of nonmaturing arteriovenous (AV) fistulae continues to be a controversial issue. While coil embolization of accessory side‐branch veins can be performed to encourage maturation of nonmaturing AV fistulae, the true efficacy and optimal patient population are not well understood. Fistulagrams performed on nonmaturing AV fistulae were retrospectively reviewed in 145 patients (86 males, median age 63 years) for the presence of accessory veins. Fistula and accessory vein measurements were obtained, as were rates of eventual fistula maturation after accessory vein coil embolization. Of 145 nonmaturing fistulae, 49 (34%) had a stenosis without any accessory veins, 76 (52%) had a stenosis and one or more accessory veins, and 20 (14%) had an accessory vein without concurrent stenosis. Eighteen AV fistulae had one or more accessory veins without coexisting stenosis. Nine fistulae had a caliber decrease immediately downstream from the accessory vein. Coil embolization of dominant accessory veins with a caliber decrease immediately downstream (n = 6) resulted in a 100% eventual fistula maturation rate versus 67% for fistulae without this configuration (n = 6, p = 0.15). Accessory vein size was not correlated with maturation rates (p = 0.51). The majority of nonmaturing fistulae with accessory veins had a coexisting stenosis. Higher maturation rates may result with selected anatomic parameters, although additional studies with more robust sample sizes are needed prior to definitive conclusions.

Covered Transjugular Intrahepatic Portosystemic Shunts: Accuracy of Ultrasound in Detecting Shunt Malfunction

OBJECTIVE The purpose of this study was to determine the accuracy of ultrasound for detecting transjugular intrahepatic portosystemic shunt (TIPS) malfunction in covered stents in comparison with bare metal stents. MATERIALS AND METHODS During a 6-year period, 126 TIPS angiography examinations were performed in 78 patients who had undergone a recent TIPS ultrasound examination. Radiology reports and images were retrospectively reviewed, and the sensitivity and specificity of sonographic parameters for detecting TIPS dysfunction were calculated using TIPS angiography and portosystemic gradient as the reference standards. RESULTS Of 126 paired studies, 43 were in bare metal TIPS and 83 were in covered TIPS. Peak shunt velocity of covered and bare metal TIPS measured by ultrasound showed comparable sensitivities for detection of shunt dysfunction, using both depressed (< 90 cm/s) and elevated (> 200 cm/s) peak shunt velocity criteria. However, a depressed velocity was more specific in covered TIPS (0.939 vs 0.550, p < 0.001) whereas elevated velocity was more specific in bare TIPS (0.485 vs 0.800, p = 0.041). An interval change in peak TIPS velocity greater than 25% was significantly more sensitive in detection of dysfunction in covered TIPS (0.815 vs 0.400, p = 0.015) whereas detection based on main portal vein velocities (≤ 30 cm/s) was not statistically different in the two groups. CONCLUSION Our data suggest that the accuracy of ultrasound for detection of TIPS shunt malfunction is at least as high in covered stents as in bare metal stents. Diagnostic performance for several sonographic parameters varied significantly between bare and covered stents, suggesting the need for optimization of sonographic criteria for covered stents.

May-Thurner syndrome complicating left-sided donor nephrectomy.

May-Thurner syndrome (MTS), or iliac vein compression syndrome, is an anatomic variant where the left iliac vein is compressed by the right iliac artery. Pulsatile arterial pressure causes venous intimal proliferation forming loose connective tissue ‘‘spurs,’’ which cause turbulent flow and venous thrombosis (1). Deep venous thrombosis (DVT) may be the initial presenting symptom in patients with MTS (2Y5). Patients present with left lower extremity swelling, pain, discoloration, and/or skin ulcers. If untreated, long-term sequelae include venous hypertension and insufficiency, recurring thrombosis, post-thrombotic syndrome, iliac vein rupture, and pulmonary embolism. In this case report, MTS was identified as a contributing factor for the development of extensive left lower extremity DVT after laparoscopic left donor nephrectomy. The use of minimally invasive techniques for diagnosis and treatment of MTS are discussed.

Hemi-bucket-handle tears of the meniscus: appearance on MRI and potential surgical implications

ObjectivesTo describe a type of meniscus flap tear resembling a bucket-handle tear, named a “hemi-bucket-handle” tear; to compare its imaging features with those of a typical bucket-handle tear; and to discuss the potential therapeutic implications of distinguishing these two types of tears.Materials and methodsFive knee MR examinations were encountered with a type of meniscus tear consisting of a flap of tissue from the undersurface of the meniscus displaced toward the intercondylar notch. A retrospective analysis of 100 MR examinations prospectively interpreted as having bucket-handle type tears yielded 10 additional cases with this type of tear. Cases of hemi-bucket-handle tears were reviewed for tear location and orientation, appearance of the superior articular surface of the meniscus, presence and location of displaced meniscal tissue, and presence of several classic signs of bucket-handle tears.ResultsA total of 15/15 tears involved the medial meniscus, had tissue displaced toward the notch, and were mainly horizontal in orientation. The superior surface was intact in 11/15 (73.3%). In 1/15 (6.7%) there was an absent-bow-tie sign; 6/15 (40%) had a double-PCL sign; 14/15 (93.3%) had a double-anterior horn sign.ConclusionWe describe a type of undersurface flap tear, named a hemi-bucket-handle tear, which resembles a bucket-handle tear. Surgeons at our institution feel this tear would likely not heal if repaired given its predominantly horizontal orientation, and additionally speculate the tear could be overlooked at arthroscopy. Thus, we feel it is important to distinguish this type of tear from the typical bucket-handle tear.