Contrast-induced nephropathy: what we know, what we think we know, and what we don't know

Contrast-induced nephropathy is a common but poorly understood problem. A large body of literature devoted to the subject is replete with contradictions and conflicting reports. The purpose of this article is to summarize our current understanding of the problem by reviewing some of the best studies done to date. Recommendations based on the current literature are also provided.

Unconventional central access: catheter insertion in collateral or in recanalized veins

Catheter hemodialysis is an unfortunate but necessary option for patients with end-stage kidneys. Patients on chronic catheter hemodialysis often slowly exhaust veins in the neck and chest, necessitating use of unconventional veins such as the femoral veins, translumbar inferior vena cava, hepatic veins, or recanalized or collateral veins. Recanalized or collateral veins are an attractive option because using these veins preserves the limited remaining access sites. Patients favor this approach because catheter care is simplified; catheters inserted in these veins appear identical to catheters inserted in the internal or external jugular veins.

Use of retrievable filters in alternative common iliac vein location in high-risk surgical patients

PURPOSE

To evaluate the use of retrievable filters placed in bilateral common iliac veins in high-risk surgical patients.

MATERIALS AND METHODS

During the 4-year study period, 10 patients received bilateral common iliac vein placement of retrievable filters for pulmonary embolism (PE) prophylaxis. These patients were at risk for venous thromboembolism (VTE) but had no evidence of VTE at the time of filter placement. In nine patients undergoing bariatric surgery, placement of a filter in the inferior vena cava (IVC) was impossible because of megacava (defined as caval diameter ≥ 3.0 cm). In one patient who had planned dissection of an extensive retroperitoneal tumor, there was concern that IVC location of the filter would be prone to complications secondary to intraoperative manipulation. Filter placement and retrieval were evaluated. All patients were followed clinically until 4-6 weeks after filter retrieval.

RESULTS

There were 20 filters placed in 10 attempts, 18 (nine patients) through the right internal jugular vein and 2 (one patient) through bilateral femoral veins. The mean (± standard deviation) dwell time of the filters was 40 days ± 10 (range 30-71 days). All filters were successfully removed. There were no procedural complications. No clinically evident PE was noted.

CONCLUSIONS

Use of retrievable filters in the bilateral common iliac veins was found to be feasible and effective in preventing PE in patients with contraindications to filter placement in the IVC.

Characteristic differences in cephalic arch geometry for diabetic and non-diabetic ESRD patients

BACKGROUND

Fistula access in chronic haemodialysis patients is recommended. The first and second choice for location of fistula placement is radial-cephalic followed by the brachiocephalic fistula. Fistula access using the cephalic vein often results in cephalic arch stenosis that is less common in diabetics for unclear reasons. The objective of the current study is to determine if geometry of the cephalic arch differs between diabetics and non-diabetics.

METHODS

In a retrospective design, 57 patients with brachiocephalic fistula access had radiology films of the cephalic arch reviewed for geometric analysis. Twelve patients were excluded from final analysis because of stent placement in the cephalic arch. Measurements made included diameter of the cephalic vein, minimum radius of curvature and angle of the arch. Demographics were statistically analysed to determine the association with the geometric measurements.

RESULTS

Global and local measurements showed evidence of two arch types. Wider arch angles and larger R/d were associated with diabetes by univariate (P < 0.05) and multivariate analyses (P < 0.05). A wider arch angle was also associated with a history of right permcath access by multivariable analysis (P = 0.042).

CONCLUSIONS

Based on this study, it was found that there are two distinct types of cephalic arch geometries. Patients having diabetes mellitus show a significant probability of having a larger R/d ratio and wider arch angle. This study has given insight into structural alterations in geometry of the cephalic arch of diabetics with brachiocephalic fistula access.

Novel devices for wound closure in interventional radiology

Wound closure issues are not as common in the field of interventional radiology when compared with other surgical fields, such as plastic surgery or dermatology. A common exception to this rule involves the placement and removal of chest wall vascular ports. This article reviews newer wound closure devices such as skin adhesives and closure film.

Percutaneous treatment of venous outflow obstruction in pediatric liver transplants

PURPOSE

To evaluate the efficacy and safety of percutaneous dilation in the treatment of impaired venous outflow in pediatric patients with liver transplants.

MATERIALS AND METHODS

Review was undertaken of the records of 35 procedures to dilate impaired venous outflow in 16 consecutive children (aged 11 days to 17.8 years; mean, 7.2 +/- 5.8 y) after liver transplantation over a period of 8 years. Patients presented clinically with signs or symptoms of obstruction of the hepatic venous or inferior vena cava anastomosis and/or abnormal noninvasive imaging findings and were referred primarily to the interventional radiology department for treatment. None were excluded. Technical and clinical success rates were calculated. After venoplasty, patients with incomplete venographic resolution or pressure gradients exceeding 5 mm Hg were treated with stents. Seven died or required repeat transplantation during the study period for reasons unrelated to venous outflow obstruction. Patency rates were calculated for all other patients with sufficient follow-up in the pediatric hepatology clinic.

RESULTS

The combined technical success rate for venoplasty (12 of 16) and stent placement (three of 16) was 94% (15 of 16), and the clinical success rate was 81% (13 of 16). One minor complication occurred: a transient hypoxic episode. Primary patency rates were 72.7% (eight of 11) at 3 months, 60% (six of 10) at 6 months, 55.6% (five of nine) at 12 months, 50% (four of eight) at 18 months, and 50% (three of six) at 36 months. Primary assisted and secondary patency rates were 90.9% (10 of 11) at 3 months, 90% (nine of 10) at 6 months, 88.9% (eight of nine) at 12 months, 87.5% (seven of eight) at 18 months, and 83.3% (five of six) at 36 months.

CONCLUSIONS

Excellent technical and clinical success rates can be achieved with percutaneous dilation of impaired venous outflow after pediatric liver transplantation. Long-term patency may require repeated interventions.

Transjugular intrahepatic portosystemic shunt placement in patients with cirrhosis and concomitant portal vein thrombosis

PURPOSE

To determine the safety and efficacy of transjugular intrahepatic portosystemic shunt (TIPS) creation in patients with liver cirrhosis complicated by thrombosed portal vein.

METHODS

This study reviewed 15 cases of TIPS creation in 15 cirrhotic patients with portal vein thrombosis at our institution over an 8-year period. There were 2 women and 13 men with a mean age of 53 years. Indications were refractory ascites, variceal hemorrhage, and refractory pleural effusion. Clinical follow-up was performed in all patients.

RESULTS

The technical success rate was 75% (3/4) in patients with chronic portal vein thrombosis associated with cavernomatous transformation and 91% (10/11) in patients with acute thrombosis or partial thrombosis, giving an overall success rate of 87%. Complications included postprocedural encephalopathy and localized hematoma at the access site. In patients with successful shunt placement, the total follow-up time was 223 months. The 30-day mortality rate was 13%. Two patients underwent liver transplantation at 35 days and 7 months, respectively, after TIPS insertion. One patient had an occluded shunt at 4 months with an unsuccessful revision. The remaining patients had functioning shunts at follow-up.

CONCLUSION

TIPS creation in thrombosed portal vein is possible and might be a treatment option in certain patients.