Mid-Term Outcomes of Patients with Central Venous Occlusive Disease Undergoing Surveillance Venography and Intervention

INTRODUCTION@#To evaluate the mid-term outcomes of regular surveillance venography with or without percutaneous transluminal angioplasty (PTA) in haemodialysis patients presenting with central venous occlusive disease.@*MATERIALS AND METHODS@#A single-centre retrospective analysis of haemodialysis patients who presented with central vein occlusion (CVO) and central vein stenosis (CVS) between January 2008 and December 2011 was performed. CVO and significant CVS were defined as 100% and >50% luminal narrowing, respectively. Upon successful angioplasty on first presentation, patients were followed up with regular surveillance venography within 3-6 months of the intervention and were re-treated when a significant stenosis or occlusion was demonstrated. Data on patient's demographics, comorbidities, presenting symptoms, type of upper limb dialysis access, lesion characteristics and complications were collected. Technical success, primary patency and primary assisted patency were analysed.@*RESULTS@#Thirty-five patients with CVO and 77 patients with CVS were enrolled. The technical success of initial PTA was 77% and 73% for the CVO and CVS groups, respectively. The primary patency at 3 months was 65% and 55% for the CVO group and CVS group, respectively ( = 0.32). The primary assisted patency at 1 year was 88% and 99% for the CVO group and CVS group, respectively ( = 0.009). At 2 years, the primary assisted patency were 77% and 90%, respectively ( = 0.07). There was significant difference in the overall primary assisted patency ( = 0.048) between the CVO and CVS groups.@*CONCLUSION@#CVOs are more difficult to treat than CVS. High primary assisted patency rates can be achieved with surveillance venography, albeit at the expense of increased number of interventions. Further cost effectiveness studies need to be performed to study the true benefit of our surveillance programme.

Single-centre retrospective review of risk factors for local tumour progression and complications in radiofrequency ablation of 555 hepatic lesions

INTRODUCTION@#This study aimed to assess safety, local tumour progression (LTP) and risk factors for LTP after radiofrequency ablation (RFA) of liver tumours in a single centre.@*METHODS@#All consecutive patients treated with RFA for liver tumours between January 2009 and October 2012 were included. Previously treated lesions that progressed were excluded. Using electronic medical records, the following data was captured: patient demographics, pre-procedural laboratory results, Child-Pugh status, tumour characteristics, development of tumoral seeding, RFA complications and LTP. Possible risk factors for LTP were identified using Cox regression.@*RESULTS@#In total, 555 liver tumours were treated in 337 patients. 483 (87.0%) hepatocellular carcinomas, 52 (9.4%) colorectal metastases and 20 (3.6%) other tumour types were treated. Mean tumour size was 2.1 ± 1.1 (range 0.4-6.8) cm. Mean follow-up duration was 387 days. 416 (75.0%) lesions had no LTP at the last imaging. 70 (12.6%) patients had minor complications requiring observation, while 7 (1.3%) patients had significant complications requiring prolonged hospitalisation or further interventions. Only one case of tumour seeding was detected. Using multivariate Cox regression, the following factors were statistically significant in predicting LTP: hilar location (relative ratio [RR] 3.988), colorectal metastases (RR 2.075), size (RR 1.290) and younger age (RR 0.982).@*CONCLUSION@#RFA of liver tumours is safe and effective, with a low significant complication rate of 1.3%. Hilar lesions are most prone to LTP, followed by lesions that were larger in size and colorectal metastases. 75.0% of patients showed no LTP at the last follow-up.

Percutaneous Endovascular Treatment to Salvage Non-Maturing Arteriovenous Fistulas in a Multiethnic Asian Population

<p><b>INTRODUCTION</b>An arteriovenous fistula (AVF) is the preferred method for haemodialysis in patients with end-stage renal failure. Previous studies have shown value in attempting percutaneous transluminal angioplasty (PTA) to salvage AVFs that fail to mature, but they are relatively small in size and mainly reported in Western populations. We reviewed our data of PTA in non-maturing AVFs to establish whether this technique is translatable to our local multiethnic population.</p><p><b>MATERIALS AND METHODS</b>We retrospectively reviewed the medical records and procedural images of 105 patients who had PTA for non-maturing AVFs performed at our department from January 2008 to January 2011. Technical success was defined as ≤30% residual stenosis after angioplasty. Clinical success was defined as at least 1 successful haemodialysis session within 4 weeks after PTA.</p><p><b>RESULTS</b>All 105 patients underwent angioplasty for at least 1 haemodynamically significant stenosis. Six (5.7%) had additional embolisation of accessory veins. Technical success was achieved in 95.2% of cases. The clinical success rate was 76.2%. Primary patency rates at 3, 6 and 12 months were 83%, 45% and 28%, respectively. Secondary patency rates at 3, 6 and 12 months were 90%, 79% and 70%, respectively. The minor complication rate was 18.1%. No major complications were encountered. An average of 1.7 interventions per access-year was required to maintain AVF patency. Patients with a preoperative vein size >2.0 mm and age <55 years were more likely to achieve clinical success, although not statistically significant.</p><p><b>CONCLUSION</b>PTA is a viable option to help salvage non-maturing AVFs in a multiethnic Asian population.</p>

Application of a standardised protocol for hepatic venous pressure gradient measurement improves quality of readings and facilitates reduction of variceal bleeding in cirrhotics

<p><b>INTRODUCTION</b>Hepatic venous pressure gradient (HVPG) measurement is recommended for prognostic and therapeutic indications in centres with adequate resources and expertise. Our study aimed to evaluate the quality of HVPG measurements at our centre before and after introduction of a standardised protocol, and the clinical relevance of the HVPG to variceal bleeding in cirrhotics.</p><p><b>METHODS</b>HVPG measurements performed at Singapore General Hospital from 2005-2013 were retrospectively reviewed. Criteria for quality HVPG readings were triplicate readings, absence of negative pressure values and variability of ≤ 2 mmHg. The rate of variceal bleeding was compared in cirrhotics who achieved a HVPG response to pharmacotherapy (reduction of the HVPG to < 12 mmHg or by ≥ 20% of baseline) and those who did not.</p><p><b>RESULTS</b>126 HVPG measurements were performed in 105 patients (mean age 54.7 ± 11.4 years; 55.2% men). 80% had liver cirrhosis and 20% had non-cirrhotic portal hypertension (NCPH). The mean overall HVPG was 13.5 ± 7.2 mmHg, with a significant difference between the cirrhosis and NCPH groups (p < 0.001). The proportion of quality readings significantly improved after the protocol was introduced. HVPG response was achieved in 28 (33.3%, n = 84) cirrhotics. Nine had variceal bleeding over a median follow-up of 29 months. The rate of variceal bleeding was significantly lower in HVPG responders compared to nonresponders (p = 0.025).</p><p><b>CONCLUSION</b>The quality of HVPG measurements in our centre improved after the introduction of a standardised protocol. A HVPG response can prognosticate the risk of variceal bleeding in cirrhotics.</p>

Portobiliary fistula: successful transcatheter treatment with embolisation coils

Although portobiliary fistula is a recognised complication of percutaneous transhepatic biliary drainage, it is extremely uncommon and can result in haemobilia. Herein, we present a case of complicated transhepatic biliary drainage catheter insertion in a patient with underlying hepatitis B liver cirrhosis, which resulted in a portobiliary fistula. The patient had a preoperative transhepatic biliary drainage procedure done prior to a Whipple's operation for a large, obstructive, gastrointestinal stromal tumour of the duodenum. To the best of our knowledge, this is the first case in the English medical literature reporting the successful treatment of portobiliary fistula by embolisation of its tract with embolisation coils, without compromising the portal vein or bile ducts.

Percutaneous transluminal angioplasty of transplant renal artery stenosis

<p><b>INTRODUCTION</b>This study aimed to assess the outcome of percutaneous transluminal angioplasty (PTA) as the primary treatment for transplant renal artery stenosis (TxRAS).</p><p><b>MATERIALS AND METHODS</b>A retrospective review of PTA of TxRAS from April 1999 to December 2008 was performed. Twenty-seven patients (17 males (M):10 females (F)) with the mean age of 49.5 years underwent PTA of TxRAS in the review period. Indications for PTA were suboptimal control of hypertension (n=12), impaired renal function (n=6) and both suboptimal control of hypertension and impaired renal function (n=9). All patients had doppler ultrasound scans prior to their PTA. In addition, 5 of these patients had computed tomography angiography (CTA) and another 7 had magnetic resonance angiography (MRA) evaluation. Mean follow-up period was 57.0 months (range, 7 to 108 months).</p><p><b>RESULTS</b>The stenotic lesions were located proximal to the anastomosis (n=2), at the anastomosis (n=15), and distal to the anastomosis (n=14). Technical success rate was 96.3%. One case was complicated by extensive dissection during PTA, resulting in subsequent graft failure. The overall clinical success rate was 76.9%. Seven out of 26 patients had restenoses (26.9% of cases). These were detected at a mean of 14.3 months post angioplasty (range, 5 to 38 months). All 7 patients underwent a second PTA successfully. Three of these patients required more than 1 repeat PTA.</p><p><b>CONCLUSION</b>PTA is safe and effective in the management of symptomatic TxRAS and should be the primary treatment of choice. Close surveillance for restenosis is required and when diagnosed, re-angioplasty can be performed.</p>

Single centre experience of transjugular liver biopsy in 152 patients

<p><b>INTRODUCTION</b>Liver biopsy is considered the definitive investigation in the diagnosis and management of liver disease. This study describes the experience of performing transjugular liver biopsy (TJLB) over the last 9 years in a local single centre.</p><p><b>MATERIALS AND METHODS</b>A retrospective review of consecutive TJLB procedures performed at our institution was conducted. A total of 152 patients (74 males and 78 females), with a mean age of 47.4 years (range, 13 to 83 years) underwent a total of 154 TJLB procedures at our institution between March 2003 and November 2011. The principal indication for TJLB was severe coagulopathy in over 80% of patients. The technical success, number of passes, histological adequacy and complication rates were analysed.</p><p><b>RESULTS</b>The procedural success rate was 98.7% (152 out of 154 procedures). Adequate material for diagnosis was obtained in 149 out of 152 (98.0%) technically successful procedures. There was procedure related morbidity in 8 patients (5.2%) of which all but one were self-limiting requiring no further intervention. We also performed hepatic venous pressure gradient (HVPG) measurements in 19% of patients at the time of TJLB.</p><p><b>CONCLUSION</b>TJLB performed at our institution is a safe and reliable technique in patients in whom traditional percutaneous liver biopsy may be hazardous. TJLB has a high technical success rate as well as a high diagnostic yield with a low complication rate. TJLB also has the added benefit of performing HVPG, which is of increasing importance in management and prognostication of chronic liver disease.</p>

C-arm Cone Beam Computed Tomography: A New Tool in the Interventional Suite

<p><b>INTRODUCTION</b>C-arm Cone Beam CT (CBCT) is a technology that is being integrated into many of the newer angiography systems in the interventional suite. Due to its ability to provide cross sectional imaging, it has opened a myriad of opportunities for creating new clinical applications. We review the technical aspects, current reported clinical applications and potential benefits of this technology.</p><p><b>MATERIALS AND METHODS</b>Searches were made via PubMed using the string "CBCT", "Cone Beam CT", "Cone Beam Computed Tomography" and "C-arm Cone Beam Computed Tomography". All relevant articles in the results were reviewed.</p><p><b>RESULTS</b>CBCT clinical applications have been reported in both vascular and non-vascular interventions. They encompass many aspects of a procedure including preprocedural planning, intraprocedural guidance and postprocedural assessment. As a result, they have allowed the interventionalist to be safer and more accurate in performing image guided procedures. There are however several technical limitations. The quality of images produced is not comparable to conventional computed tomography (CT). Radiation doses are also difficult to quantify when compared to CT and fluoroscopy.</p><p><b>CONCLUSION</b>CBCT technology in the interventional suite has contributed significant benefits to the patient despite its current limitations. It is a tool that will evolve and potentially become an integral part of imaging guidance for intervention.</p>

Cone beam computed tomography for vascular interventional radiology procedures: early experience

<p><b>INTRODUCTION</b>Cone beam computed tomography (CBCT) is a relatively new technological innovation that utilises fl at-panel detector technology to obtain CT-like images. The key strength of a CBCT system is that cross-sectional imaging can be obtained using the angiographic fl at panel unit without having to move the patient, allowing the radiologist to obtain soft tissue imaging during the procedure. This allows treatment planning, guidance, and assessment of outcome to be performed in one interventional suite.</p><p><b>MATERIALS AND METHODS</b>From December 2008 to June 2009, 24 CBCT scans were performed during vascular interventional procedures on our department's newly installed multi-axis fl at panel angiographic unit.</p><p><b>RESULTS</b>Ten cases were performed for hepatic trans-arterial chemoembolisation, 9 cases for hepatic arterial Yttrium-90 infusion, while 5 cases were for other indications. CBCT was found to be useful in 20 of the 24 cases.</p><p><b>CONCLUSION</b>Our early experience showed that CBCT was useful in impacting decisions during selected vascular interventional procedures. As CBCT technology improves, we can foresee wider applications of this technology.</p>

Stent-assisted percutaneous angioplasty for extra-cranial carotid disease:experience at Singapore General Hospital

<p><b>INTRODUCTION</b>This study aims to analyse the results of carotid stenting in a tertiary referral centre in Singapore.</p><p><b>MATERIALS AND METHODS</b>Retrospective analysis of all carotid artery stenting (CAS) cases in a single centre from March 1997 to December 2008 was performed. Sixty successful procedures were performed in 61 patients, with bilateral stenting in 1 patient, and 2 failed procedures. The majority were Chinese (78.7%) and males (77.0%), with a high proportion having hypertension (82.0%) and hypercholesterolaemia (78.7%). The majority (91.8%) of patients were high surgical risk candidates, primarily due to cardiac risk factors. Ten patients (16.4%) had prior neck irradiation for nasopharyngeal carcinoma, and 3 patients each (4.9%) had previous endarterectomy and contralateral occlusion. A distal embolic protection device was used in 71.7% of cases.</p><p><b>RESULTS</b>Technical success was 96.8%. The 30-day stroke and death rate was 13.8%, comparable to reported results for this high surgical risk population.</p><p><b>CONCLUSION</b>CAS is a technically feasible and a relatively safe alternative to endarterectomy to treat extracranial carotid stenosis, especially in patients who are inoperable or at high surgical risk.</p>

Image-guided radiofrequency ablation of liver malignancies: experience at Singapore General Hospital

<p><b>UNLABELLED</b>The aim of this paper was to study the efficacy, side effects and complications of radiofrequency (RF) ablation of primary and metastatic liver malignancies.</p><p><b>MATERIALS AND METHODS</b>We retrospectively reviewed 57 patients (39 men, 18 women; mean age, 63 years; age range, 44 to 83 years) who underwent RF ablation for liver malignancies from January 2002 to December 2004. A total of 87 tumours were ablated - 71 (81.6%) hepatocellular carcinomas and 16 (18.4%) metastases (from primaries in the colon, stomach and pancreas). RF ablation was performed either percutaneously (n = 71) under conscious sedation or intraoperatively (n = 16) under general anaesthesia. Follow-up ranged from 1 month to 41 months (mean, 15.2) and included computed tomography (CT) 1 day, 1 month and 3 months after ablation, and half-yearly thereafter. Patients were observed for local tumour progression and for the emergence of new tumours.</p><p><b>RESULTS</b>Four patients with a total of 5 tumours were lost to follow-up. Of the remaining 82 tumours treated, complete ablation was attained in 66 tumours after a single procedure, giving a primary effectiveness rate of 80.5%. Seven (8.5%) required 2 procedures to achieve complete ablation, giving a secondary effectiveness rate of 89% after 2 ablations. One tumour (1.2%) required 3 procedures to achieve complete ablation. One tumour required 4 procedures to date, with the latest follow-up CT still demonstrating incomplete ablation. Two tumours (2.4%) had an initial RF ablation and subsequent transarterial chemoembolisation (TACE). One tumour had an initial RF ablation followed by 32Phosphorus-biosilicon (BrachySil) injection, the latter as part of a Phase IIA trial. One tumour required 2 RF ablations and a subsequent TACE. Lastly, 3 tumours received initial RF ablation but subsequent local tumour progression was not treated as the patients were deemed unfit for repeat ablation. No procedure-related deaths or major complications were encountered. Minor complications were reported in 2 patients (3.8%) - subcapsular haematoma and thermal injury to the adjacent gastric antrum, both not necessitating surgical intervention.</p><p><b>CONCLUSIONS</b>RF ablation is an effective, safe and relatively simple procedure for the treatment of unresectable liver malignancies.</p>