Comparison of pharmacological thrombolysis with mechanical thrombectomy in thrombosed arteriovenous fistulas and grafts: a systemic review and meta-analysis

AIM

To compare the effectiveness and safety of pharmacological thrombolysis and mechanical thrombectomy.

MATERIAL AND METHODS

This review was conducted in accordance with the PRISMA guidelines. Pooled proportions and subgroup analysis were calculated for primary and secondary patency rates, technical success, clinical success, major and minor complications rates.

RESULTS

This systematic review identified a total of 6,492 studies of which 17 studies were included for analysis. A total of 1,089 patients comprising 451 (41.4 %) and 638 (58.6 %) patients who underwent thrombolysis and mechanical thrombectomy procedures, respectively, were analysed. No significant differences were observed between thrombolysis and mechanical thrombectomy procedures in terms of technical success, clinical success, major and minor complications rates, primary and secondary patency rates; however, subgroup analysis of overall arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) demonstrated a significantly higher rate of major complications within the AVF group (p=0.0248).

CONCLUSION

The present meta-analysis suggests that pharmacological thrombolysis and mechanical thrombectomy procedures are similarly effective and safe; however, AVFs are subject to higher major complications compared to AVGs.

Utility of paclitaxel-coated balloons for the treatment of infrainguinal disease in the Asian population - 24-month outcome data from the BIOLUX P-III Global Registry 24-month Asian outcomes of BIOLUX P-III

BACKGROUND

Results from the BIOLUX P-III registry have demonstrated favourable outcomes of Passeo-18 Lux™ (Biotronik®, Buelach, Switzerland) drug-coated balloon in treating obstructive infrainguinal peripheral artery disease, but it has not been established if Asians would benefit to the same extent as non-Asians.

METHODS

A subgroup analysis was performed on the 24-month data comparing the Asian cohort (AC) to non-Asian cohort (NAC).

RESULTS

AC included 49 patients with 77 lesions. AC was significantly younger (65.6 vs 70.3 years, p < 0.05), had more diabetes (87.8% vs 45.3%, p < 0.05), and was more likely to present with CLTI (73.5% vs 35.3%, p < 0.001) compared to NAC. They had significantly longer mean target lesions (115 vs 86.9 mm, p = 0.006), and received significantly higher paclitaxel doses (10.7 vs 7.2 mg, p = 0.0005). Device, technical and procedural successes were 125/125(100%), 95/97(97.5%) and 45/49(91.8%), respectively. There was no significant difference in target lesion revascularization rates between groups (10.5% vs 12%, p = 0.91). However, the AC had more major adverse events (30.2% vs 16.1%, p = 0.001), amputations (26.3% vs 6.2%, p < 0.05) and mortality (37.9% vs 10.6%, p < 0.05) at 24 months.

CONCLUSION

Passeo-18 Lux™ use was efficacious in Asians, but was associated with higher adverse events, amputations and mortality rates, likely attributable to poorer patient comorbidities and more extensive PAD.

Intervention with selution SLR™ Agent Balloon for Endovascular Latent Limus therapy for failing AV Fistulas (ISABELLA) Trial: Protocol for a pilot clinical study and pre-clinical results

BACKGROUND

The aim of this pilot clinical study is to evaluate the safety and efficacy of the Selution Sustained Limus Release (SLR)™ sirolimus-coated balloon (M.A. MedAlliance SA, Nyon, Switzerland) for improving the patency of failing arterio-venous fistulas (AVF) in hemodialysis patients. We also present herein a pre-clinical pharmacokinetic and safety evaluation of Selution™ to justify its first use in hemodialysis patients for endovascular access salvage.

METHODS AND RESULTS

This is an investigator-initiated prospective single-center, non-blinded single-arm trial. Forty patients with clinically significant de novo or recurrent stenoses in a mature AVF circuit will be recruited. All stenotic lesions will be prepared with high pressure non-compliant conventional balloon angioplasty (CBA) prior to deployment of the Sustained-Release Selution™ sirolimus drug-eluting balloon. The primary efficacy endpoint is 6-month target lesion primary patency and the primary safety endpoint is freedom from localized or systemic serious adverse events through 30 days. Secondary endpoints of interest include technical and clinical success rates and circuit access patency at 3 and 6 months. Follow-up will occur for 2 years for those patients whose AVFs remain patent. Pharmacokinetic and histological animal safety studies performed with the Selution™ coating formulation showed prolonged arterial tissue retention of sirolimus with therapeutic levels up to 60 days and non-toxic and rapidly declining blood levels. Histological results in animal models demonstrated safety, freedom from intraluminal thrombus, reduction in restenosis by sirolimus elution compared to CBA, and no evidence of embolic phenomena indicative of adverse particulate effects.

DISCUSSION

Long release sirolimus coated balloons may serve as a promising novel alternative therapy to paclitaxel-based technology for treating conduit stenosis secondary to neointimal hyperplasia. Pre-clinical pharmacokinetic and histological animal data are encouraging and provide suggestion of safety and efficacy in this setting. This single-center trial will provide a first step toward demonstration of efficacy and safety of this device for treatment of stenotic fistulas.

Registry to investigate the efficacy and safety of the VenaBlock© VeIn SEaling system for VaRicose veins in SingApore - Six months results of the RIVIERA trial

BACKGROUND

The Venablock^© Venous Closure System (Invamed, Ankara, Turkey) is a novel cyanoacrylate-based non-thermal non-tumescent embolization device to block refluxing truncal veins for chronic venous insufficiency and varicose veins. The aim was to prospectively evaluate the safety and 6 months efficacy of Venablock^© for the treatment of primary great saphenous vein (GSV) and small saphenous vein (SSV) incompetency in a multi-ethnic cohort from Singapore.

METHODS

This was a single arm, single investigator prospective study of 29 patients (39 limbs, 39 truncal veins) recruited over a 5-month period (August 2019 to February 2020), who were treated with the Venablock^© device at a tertiary vascular unit in Singapore. Patients with symptomatic varicose veins (C2-6) and had truncal reflux > 0.5 second on venous Duplex ultrasound were included. Follow-up occurred at 2 weeks, 3 and 6 months with dedicated quality of life questionnaires and a targeted Duplex ultrasound performed to check for continued venous occlusion.

RESULT

Mean age was 61.4 (±11.0) years and mean BMI was 26.2 (±5.7) kg/m². 11/29 (37.9%) were males. Most common CEAP class treated was 2 (12/29, 41.3%). Mean diameter of treated GSV was 5.7 (±2.0) mm, 4.8 (±1.7) mm and 4.2 (±1.3) mm for the proximal, mid and distal above knee segments respectively. Mean time from access puncture to sheath removal was 23.4 (±10.0) mins. Vein occlusion at 2 weeks, 3 and 6 months was 39/39 (100%), 39/39 (100%) and 36/37 (97.2%) respectively. 5/29 (17.2%) developed puncture site infections, of which 3/29 (7.7%) required formal surgical drainage. 3/29 (7.7%) developed phlebitis. At 6 months, revised Venous Clinical Severity Score improved from 5.2 (±3.5) to 2.1 (±2.9; p < .001); EuroQol-5 Dimension score, from 7.4 (±2.1) to 5.7 (±1.4; p < .001); Aberdeen Varicose Vein Questionnaire score, from 18.1 (±15.5) to 7.9 (±8.9; p = .007); and Chronic Venous Insufficiency Questionnaire, from 18.6 (±16.2) to 4.5 (±6.3; p < .001).

CONCLUSION

Venablock^© is a safe and efficacious option of treating truncal venous insufficiency in a multi-ethnic Asian cohort from Singapore in the short term. There is a significant improvement in QoL. Longer follow-up is required to assess the durability of this technique, in particular the higher puncture site infection rates observed compared to other glue-based therapies.

A review of the Turned-down Onto Pericapsular-tissue Hemisectioned Amputated Toe (TOPHAT) flap for wound coverage during ray amputations of the toes

INTRODUCTION

Exposure of the adjacent Metatarsal-Phalangeal Joint (MTPJ) commonly occurs after application of Topical Negative Pressure Wound Therapy (TNPWT) for a ray amputation wound. This is due to mechanical soft tissue erosion or trauma to the adjacent digital artery from direct pressure effect. This results in toe gangrene requiring a ray amputation and ultimately a larger wound bed. We describe the use of the Turned-down Onto Pericapsular-tissue Hemisectioned Amputated Toe (TOPHAT) flap - a filleted toe flap to protect the adjacent MTPJ capsule combined with a novel Negative Pressure Wound Therapy with instillation and dwell-time (NPWTi-d) dressing technique. The flap protects the adjacent joint capsule and reduces the wound burden whilst allowing the wound to benefit from TNPWT, thereby accelerating wound healing.

MATERIAL AND METHODS

A retrospective review was conducted of patients with toe gangrene requiring ray amputation that underwent the TOPHAT flap on in our institution from 2019 and 2020. Complications such as wound dehiscence, hematoma, flap necrosis and secondary infection were recorded. Other outcomes recorded were time taken to final skin grafting and time taken for complete wound epithelialization.

RESULTS

9 patients underwent treatment with the TOPHAT flap. 2 patients had flap necrosis. 7 patients progressed to definitive skin coverage with skin grafting. One patient subsequently had progressive arterial disease despite successful skin grafting and required above knee amputation. The mean time to final skin grafting and complete wound epithelialization was 49.5 days and 107.5 days respectively. All patients were satisfied with the outcomes and were able to return to their pre-morbid function.

CONCLUSIONS

The TOPHAT flap has a consistent vascular supply that provides durable soft tissue coverage. It is a robust and easily reproducible technique to accelerate wound healing after ray amputations even in patients with peripheral vascular disease.

Does reducing radiation levels for procedures affect image quality and radiation to proceduralists? A double-blinded randomised study of two protocols

AIM

To evaluate the ultra-lose dose imaging protocol (ULDP), compared to the standard low-dose imaging protocol (LDP), which are used for haemodialysis access, in terms of radiation exposure and image quality.

MATERIAL AND METHODS

This was a single-centre, institutional review board-approved, prospective, double-blinded randomised controlled study to compare radiation exposure and image quality of the ULDP and LDP. Ten proceduralists, two radiographers, and 11 nurses were enrolled. Radiation exposure during 80 procedures (40 angioplasties and 40 thrombolysis) was recorded (direct radiation to patients from protocol report and scattered radiation to participants from the RaySafe i2 real-time dosimetry system). Baseline characteristics of procedure were recorded. Image quality was assessed subjectively using questionnaires based on the five-point Likert scale after each procedure.

RESULTS

Compared with LDP, the use of ULDP was associated with a significantly lower rate of radiation exposure to proceduralists, patients, and scrub nurses (0.506±0.430 versus 0.847±0.965 μSv/s, p=0.044; 0.571±1.284 versus 1.284±1.007 mGy/s, p<0.001; and 0.052±0.071 versus 0.141±0.185 μSv/s, p=0.005, respectively). No significant difference in image quality or duration of procedure was observed (all p values >0.05).

CONCLUSION

Compared with LDP, the use of ULDP was associated with a significantly lower rate of radiation exposure to proceduralists, patients, and scrub nurses without compromising the image quality or duration of procedure.

Helical stent (SUPERA™) and drug-coated balloon (Passeo-18 Lux™) for recurrent cephalic arch stenosis: Rationale and design of arch V SUPERA-LUX Study

BACKGROUND

The treatment options for cephalic arch stenosis are limited and standard of care remains at crossroads - none are ideal and there is currently no gold standard. Endovascular techniques are now the preferred primary therapeutic option because they are minimally invasive and better tolerated by haemodialysis patients who have multiple comorbidities. However, conventional plain old balloon angioplasty, bare metal stenting and stent grafts all have their limitations. The aim of this trial is to evaluate whether the helical SUPERA™ stent (Abbott Vascular, Santa Clara, CA, USA), which has a higher degree of flexibility and resistance to compressive forces compared to traditionally laser-cut nitinol stents, combined with a drug-coated balloon (Biotronik Passeo-18 Lux™) to minimize the neointimal hyperplasia effect, can improve patency and reduce reintervention rates.

METHODS AND RESULTS

Arch V SUPERA-LUX is a pilot investigator-initiated single-centre, single-arm prospective study. Twenty patients with a brachiocephalic fistula within 6 months of initial plain old balloon angioplasty for significant cephalic arch stenosis will be recruited for treatment with SUPERA and drug-coated balloon. The primary objectives are immediate angiographic and procedural success, primary patency and functional fistula at 1 week, 8 weeks, 6 and 12 months. The results from eight patients treated prospectively as proof of concept have shown primary patency of 83.3% at 1 year with 100% technical and procedural success rates. Enrolment for the Arch V SUPERA-LUX study is expected to be completed at the end of 2019.

CONCLUSION

The Arch V SUPERA-LUX study is the first trial to evaluate whether SUPERA stent implantation and drug-coated balloon use can provide superior protection against restenosis compared to traditional angioplasty, bare metal stents and stent grafts in recurrent cephalic arch stenosis. Initial pilot results are encouraging but longer follow-up is required to truly test this technique.

TRIAL REGISTRATION

This study is registered on ClinicalTrials.gov NCT03891693.

A comparison between Caucasian and Asian superficial venous anatomy and reflux patterns – Implications for potential precision endovenous ablation therapy

Objectives

The aim of this study is to investigate whether there are differences between predominantly Caucasians and Asians from two disparate cohorts around the globe, with regard to their pre-operative venous reflux patterns and truncal vein characteristics, which could potentially help clinicians tailor venous treatment for chronic venous insufficiency on a more individualised basis in different parts of the world.

Methods

A total of 200 lower limb chronic venous insufficiency duplex studies (127 Singaporean (predominantly Asian) patients) and 200 lower limb chronic venous insufficiency duplex scans (137 Americans predominantly Caucasians) were analysed and compared for differences in venous anatomy and reflux characteristics.

Results

Asian patients from Singapore presented with higher CEAP scores compared to the predominantly Caucasian cohort from the US (30% CEAP 4a or greater vs. 17.5%; p < 0.01). Singaporeans had more great saphenous vein reflux starting at the sapheno-femoral junction (86% vs. 73%; p < 0.01) and ending at the ankle (93% vs. 46%; p < 0.01). Vein diameters were generally larger in the US cohort of patients (median 5.7 mm vs. 2.9 mm; p < 0.01).

Conclusions

The predominantly Asian cohort from Singapore had smaller diameter truncal veins, longer segments of truncal vein reflux and present later with more advanced chronic venous insufficiency compared to their American counterparts. This information could help tailor endovenous ablation on a more individualised basis in the future.

Case report of a type III endoleak presenting only decades after endovascular aortic repair

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Late type III endoleak is a rare but potentially life-threatening complication post endovascular aortic aneurysm repair.

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They can present only decades after surgery, even after an extended complication-free period.

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First line treatment often employs an endovascular approach to realign the endoleak with additional stent-grafts.

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Current long-term data for EVAR-related complications highlights the need for life-long stent-graft surveillance.

Introduction: Type III endoleaks are a rare but potentially life-threatening complication post endovascular aortic aneurysm repair (EVAR).

Case report: A 91-year-old Chinese female, presented to our accident and emergency department for severe back and abdominal pain. She had previously undergone an EVAR procedure twenty years ago for a 6.5 cm diameter infra-renal abdominal aortic aneurysm. A CT aortogram revealed a type III endoleak, with the contralateral limb found to be disconnected from the main graft body. She was successfully treated by relining the graft using an endovascular technique.

Discussion: The case highlights the need for life-long stent-graft surveillance. We discuss early generation stent-grafts, type III endoleak treatment options and the current long-term data for late EVAR-related complications.

Conclusion: For patients who had undergone EVAR, type III endoleaks can present only decades later and pose a significant risk of aneurysmal rupture.

Fenestrated Endovascular Repair of Zones 1 and 2 Aortic Arch Pathologies

BACKGROUND

Surgical management of aortic arch pathologies is complex, and endovascular developments have now enabled total or hybrid endovascular aortic arch repair. We present our early experience with fenestrated aortic arch repairs in Ishimaru zones 1 and 2 pathologies.

METHODS

In a single tertiary institution, all consecutive endovascular aortic arch repairs were reviewed. A preoperative computed tomography aortogram was performed to assess anatomic suitability, which we defined as having a proximal sealing zone with a maximum diameter of 38 mm and minimum length of 20 mm, absence of significant aortic tortuosity, and suitable sealing zones in target vessels.

RESULTS

From September 2015 to February 2018, 5 cases of fenestrated aortic arch endovascular repairs were performed. There were 3 male patients. The patients were between 57 and 83 years old, all of whom were American Society of Anesthesiologists (ASA) class II or III. Indications for surgery included aortic arch aneurysms (n = 3), a symptomatic aortic dissection, and a left subclavian artery aneurysm. Three patients had a scallop to the innominate artery, and one patient had a scallop to the left common carotid artery. Fenestrations were made to 3 left common carotid arteries and 3 left subclavian arteries. In 2 patients, a left carotid-subclavian bypass was performed, and the left subclavian artery origin occluded with a vascular plug. Technical success was 100%. One patient developed a right occipital infarct and acute myocardial infarction. The mean duration of surgery was 164 min, and the mean length of stay was 4.2 days. The mean follow-up period was 14.4 months.

CONCLUSIONS

The use of fenestrated grafts in the aortic arch is a feasible treatment option. However, certain limitations still exist, and preoperative planning is important in ensuring clinical success. Although this procedure appears feasible in the short term, long-term results and durability remain to be seen.

Catheter-related complications and survival among incident hemodialysis patients in Singapore

Introduction:

Hemodialysis is the main modality of renal replacement therapy in Singapore. However, a majority of the patients in Singapore are initiated on hemodialysis via a catheter. This study examines the complication rates and factors predicting catheter-related bloodstream infections and mortality rates in patients who were initiated on hemodialysis at our institution.

Methods:

This is a single-center retrospective analysis of incident hemodialysis patients who were initiated on renal replacement therapy between 1 January 2010 and 31 December 2012. Catheter-related bloodstream infection risk factors, organisms, and associated mortality were analyzed.

Results:

The catheter-related bloodstream infection and exit site infection incidence rates were 0.75 and 0.50 per 1000 catheter days, respectively. The mean duration to first catheter-related bloodstream infection episode was 182.47 ± 144.04 catheter days. Prolonged catheter duration was found to be a risk factor for catheter-related bloodstream infection. Compared to patients initiated on dialysis via arteriovenous fistula, initiation of dialysis via catheter is strongly associated with increased mortality (6.0% vs 14.5%; p = 0.02). In particular, the presence of diabetes mellitus and development of catheter-related bloodstream infection was associated with increased mortality ( p = 0.04 and 0.05, respectively). In addition, patients who began hemodialysis before being seen by a nephrologist were associated with decreased mortality (3.4% vs 13.0%; p = 0.03).

Conclusion:

In conclusion, prolonged duration of catheter insertion is found to be a risk factor for catheter-related bloodstream infection in hemodialysis patients, and its development is associated with increased mortality. Early referral to a nephrologist and creation of arteriovenous fistula in pre-end-stage renal disease patients are pivotal in improving the outcomes of patients.

Outcomes of arteriovenous fistula creation, effect of preoperative vein mapping and predictors of fistula success in incident haemodialysis patients: A single-centre experience

AIM

Vascular access in haemodialysis is critical for effective therapy. We aim to evaluate the outcomes of arteriovenous fistula (AVF) creation in incident haemodialysis patients, impact of preoperative vein mapping and predictors of successful AVF maturation in our centre.

METHODS

Data of End-stage Renal Disease (ESRD) patients initiated on haemodialysis from January 2010 to December 2012 in our centre were retrospectively obtained from electronic medical records and clinical notes. Demographic characteristics, medical comorbidities, perioperative details were collected, and patients were followed up until 1 January 2014.

RESULTS

A total of 708 patients (median age 64, IQR 55-72) were included with mean duration of follow up of 2.3 ± 1.2 years, with access of AVF and arteriovenous graft (AVG) in 694 (98%) and 14 (2%) patients respectively. Eight patients were lost to follow-up. Successful AVF maturation was achieved in 542 patients (78%), with 1-year cumulative patency rate of 74%. Multivariate analysis revealed male gender, upper arm AVF and good postoperative thrill and pulse as predictors of successful AVF maturation. Preoperative vein mapping was performed in 42.5% (295/694) of patients, with mean vein diameter of 2.44 ± 0.82 mm. Maturation rates with and without vein mapping were 72.2% and 82.4%, respectively, (P = 0.001). In patients with vein diameters of <2 mm and ≥2 mm, there was no statistically significant difference in maturation rates (71.3% vs. 72.6%; P = 0.887) and median maturation time (66 vs. 78 days; P = 0.73).

CONCLUSION

Arteriovenous fistula can be successfully created in most incident haemodialysis patients. Routine vein mapping is not necessary if veins are suitable on physical examination alone, and vein sizes of <2 mm on ultrasound is not associated with lower AVF maturation rate.

Nipah encephalitis - an update

Between September 1998 to May 1999, Malaysia and Singapore were hit by an outbreak of fatal encephalitis caused by a novel virus from the paramyxovirus family. This virus was subsequently named as Nipah virus, after the Sungei Nipah village in Negeri Sembilan, where the virus was first isolated. The means of transmission was thought to be from bats-topigs and subsequently pigs-to-human. Since 2001, almost yearly outbreak of Nipah encephalitis has been reported from Bangladesh and West Bengal, India. These outbreaks were characterized by direct bats-to-human, and human-to-human spread of infection. Nipah virus shares many similar characteristics to Hendra virus, first isolated in an outbreak of respiratory illness involving horses in Australia in 1994. Because of their homology, a new genus called Henipavirus (Hendra + Nipah) was introduced. Henipavirus infection is a human disease manifesting most often as acute encephalitis (which may be relapsing or late-onset) or pneumonia, with a high mortality rate. Pteropus bats act as reservoir for the virus, which subsequently lead to human spread. Transmission may be from consumption of food contaminated by bats secretion, contact with infected animals, or human-to-human spread. With wide geographical distribution of Pteropus bats, Henipavirus infection has become an important emerging human infection with worldwide implication.