Byung Chul Kang

Portosystemic pressure gradient during transjugular intrahepatic portosystemic shunt with Viatorr stent graft: What is the critical low threshold to avoid medically uncontrolled low pressure gradient related complications?

Background:  Inappropriately decreased portosystemic pressure gradient (PSG) during transjugular intrahepatic portosystemic shunt (TIPS) can cause fatal complications but the critical low threshold of PSG is still not clear. The aim of the present study was to evaluate the critical low threshold of PSG during TIPS.

Comparison of a new polytetrafluoroethylene-covered metallic stent to a noncovered stent in canine ureters.

The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30–40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.

Contrast-Induced Nephropathy in Patients Undergoing Intravenous Contrast-Enhanced Computed Tomography in Korea: A Multi-Institutional Study in 101487 Patients

Objective To evaluate the prevalence of known risk factors for contrast-induced nephropathy (CIN) and their association with the actual occurrence of CIN in patients undergoing intravenous contrast-enhanced computed tomography (CECT) in Korea. Materials and Methods Patients who underwent CECT in 2008 were identified in the electronic medical records of 16 tertiary hospitals of Korea. Data on demographics, comorbidities, prescriptions and laboratory test results of patients were collected following a standard data extraction protocol. The baseline renal function was assessed using the estimated glomerular filtration rate (eGFR). We identified the prevalence of risk factors along the eGFR strata and evaluated their influence on the incidence of CIN, defined as a 0.5 mg/dL or 25% increase in serum creatinine after CECT. Results Of 432425 CECT examinations in 272136 patients, 140838 examinations in 101487 patients met the eligibility criteria for analysis. The mean age of the participants was 57.9 ± 15.5 years; 25.1% of the patients were older than 70 years. The prevalence of diabetes mellitus was 11.9%, of hypertension 13.7%, of gout 0.55% and of heart failure was 1.7%. Preventive measures were used in 40238 CECT examinations (28.6%). The prevalence of risk factors and use of preventive measures increased as the renal function became worse. A CIN was occurred after 3103 (2.2%) CECT examinations, revealing a significant association with decreased eGFR, diabetes mellitus, and congestive heart failure after adjustment. Conclusion Risk factors for CIN are prevalent among the patients undergoing CECT. Preventive measures were seemingly underutilized and a system is needed to improve preventive care.

The Primary Patency of Percutaneous Transluminal Angioplasty in Hemodialysis Patients With Vascular Access Failure

Background and Objectives Dysfunction of arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) contributes significantly to morbidity and hospitalization in the dialysis population. We evaluated the primary patency of AVFs following percutaneous transluminal angioplasty (PTA) in haemodialysis patients. Subjects and Methods We performed 231 interventions in 118 patients with a mean age of 62.1±12.9 years. We performed 122 interventions in 53 AVG patients (44.9%), and 109 interventions in 65 AVF patients (55.1%). If there was thrombosis of the vascular access, urokinase was administered and/or thrombus aspiration was performed. The stent was inserted when balloon dilatation did not expand sufficiently or elastic recoil occurred. Results For the 118 patients, the median patency time was 10.45±10.29 months at 92 months of follow-up. The primary patencies for stenotic AVFs at 6, 12, 24, 36, 48, and 60 months were 63.4%, 41.4%, 17.0%, 9.7%, 7.3%, and 2.4%, respectively. The primary patencies for AVGs at 6, 12, 24, and 36 months were 36.9%, 19.5%, 10.8%, 2.1%, respectively, and were obtained by means of the Kaplan-Meier analysis (log rank=6.42, p<0.05). The median patency time was 11.0 months and 4.45 months in the non-thrombus and thrombus groups, respectively. The complication rate was 1.73% (4/231); two cases of pseudoaneurysms and two cases of extravasation were detected. All therapy failures (5/231) occurred in thrombotic lesions of AVGs and were treated surgically. Conclusion PTA is an efficacious method for the correction of stenosis of AVFs for hemodialysis, thus prolonging the patency of the fistulas.

A Newly Designed Y-shaped Covered Stent in the Palliative Treatment of Hepatic Hilar Malignant Obstruction: Case Report

We report a case in an inoperable patient with the hilar malignant biliary obstruction treated palliatively by the use of a newly designed Y-shaped covered stent without interfering contra-lateral bile duct. We percutaneously inserted a newly designed Y-shaped covered stent into a biliary tree in an inoperable patient with Bismuth Type II cholangiocarcinoma. We checked tubograms, enhanced CT studies, and blood bilirubin levels before, one week after, and at every three month after the stenting, by observing closely the signs of clinical infection as well. The follow-up period was about 12 months. The placement of the Y-shaped covered stent was successful and resulted in adequate biliary drainage in the immediate post-procedural tubogram and in the follow-up abdominal CT. The serum bilirubin levels did not show elevation after the insertion of the Y-shaped covered stent.

A multicenter, randomized, controlled, single-blind comparison phase III study to determine the efficacy and safety of gadobutrol 1.0 M versus gadopentetate dimeglumine following single injection in patients referred for contrast-enhanced MRI of the body regions or extremities

To demonstrate the noninferiority of gadobutrol‐enhanced magnetic resonance imaging (MRI) compared with gadopentetate dimeglumine‐enhanced MRI in Asian patients referred for contrast‐enhanced imaging of the body or extremities.