Study protocol for a Prospective, Randomized controlled trial of stEnt graft and Drug-coated bAlloon Treatment for cephalic arch stenOsis in dysfunctional arteRio-venous fistulas (PREDATOR)

BACKGROUND

Treatment of cephalic arch stenosis (CAS) is associated with high risk of failure and complications. Although stent-graft (SG) placement has improved patency rates, stent edge restenosis has been raised as a potential limiting factor for SG usage in CAS. This study aims to evaluate the safety and efficacy of combining stent graft placement with paclitaxel-coated balloon (PCB) angioplasty versus PCB alone in the treatment of CAS.

METHODS

This is an investigator-initiated, prospective, international, multicenter, open-label, randomized control clinical trial that plans to recruit 80 patients, who require fistuloplasty from dysfunctional arteriovenous fistula (AVF) from CAS. Eligible participants are randomly assigned to receive treatment with SG and PCB or PCB alone in a 1:1 ratio post-angioplasty (n = 40 in each arm). Randomization is stratified by de novo or recurrent lesion, and the participants are followed up for 1 year. The primary endpoints of the study are target lesion primary patency (TLPP) and access circuit primary patency (ACPP) rates at 6-months. The secondary endpoints are TLPP and ACPP at 3- and 12-month; target lesion and access circuit assisted primary and secondary patency rates at 3, 6, and 12-months and the total number of interventions; complication rate; and cost-effectiveness.

DISCUSSION

This study will evaluate the clinical efficacy and safety of combination SG and PCB implantation compared to PCB alone in the treatment of CAS for hemodialysis patients.

Sirolimus-coated balloon angioplasty in maintaining the patency of thrombosed arteriovenous graft: 1-year results of a prospective study

BACKGROUND

A prospective, pilot study was designed to test the feasibility of using sirolimus-coated balloon (SCB) to treat graft vein junction of thrombosed arteriovenous graft (AVG) following successful pharmacomechanical thrombectomy. The present report provides the 1-year results of this study.

METHODS

This is a 1-year follow-up of a single, prospective, single-arm study that was conducted from 2018 to 2019 in 20 patients who presented to a tertiary institution with thrombosed AVG. The recruited patients received SCB angioplasty at the graft-vein junction following successful endovascular thrombectomy of a thrombosed AVG. One year after recruitment, there were three deaths, one AVG revision, and one AVG explantation among the participants recruited. The outcomes of 15 subjects at 1-year following the index procedure obtained from electronic medical records were re-examined.

RESULTS

The 1-year access circuit primary patency rate was 40%, while assisted primary and secondary patency rates were 46.7% and 73.3%, respectively. A total of 16 interventions (4 angioplasties, 12 thrombectomies) were performed in 9 patients over the 12 months. Four AVGs were abandoned. The median number of interventions per patient was 1 (0-3) per year. Using Kaplan-Meier analysis, the mean estimated post-intervention access circuit primary patency was 230 (95% CI: 162-300) days, while access circuit assisted primary patency was 253 (95% CI: 187-320) days, and access circuit secondary patency was 292 (95% CI: 230-356) days. Sub-group analysis did not show a significant difference in the mean estimated primary patency between AVG with de novo and recurrent stenosis (245 days, 95% CI: 151-339 vs 210 days, 95% CI: 113-307; p = 0.29).

CONCLUSIONS

SCB may help sustain the patency of thrombosed AVG following successful thrombectomy.

Efficacy and safety of low dose, weight-based subcutaneous enoxaparin protocol in recurrent arteriovenous access thrombosis

BACKGROUND

This study aims to evaluate the safety and efficacy of a short-term, low dose, weight-based subcutaneous enoxaparin protocol (SEP) in maintaining the patency of arteriovenous (AV) access with recurrent thrombosis.

METHODS

Prospective follow-up of 25 patients who presented to a tertiary institution with recurrent AV access thrombosis and treated with anticoagulation according to SEP following successful thrombectomy. Patency and safety outcomes of SEP were studied.

RESULTS

The participants were 66.4 ± 10.2 years old and predominantly male (60%) and of Chinese ethnicity (72%). The AV accesses had a median age of 1.4 (0.6, 5.6) years with 60% being non-autogenous arteriovenous access while 40% were autogenous arteriovenous access. Thrombolytic agents (urokinase (72%) or alteplase (28%)) were used in all procedures while adjunct thrombectomy device was used in only four procedures. The mean dose of enoxaparin was 36.0 ± 8.2 mg or 0.64 ± 0.1 mg/kg/day for a mean duration 30.0 days (Interquartile range: 27.5, 31.0). One patient developed minor bleeding episode. Kaplan-Meier analysis demonstrated that the mean thrombosis-free survival pre- versus post-SEP adoption was 27.3 (95% CI 17.9-36.7) versus 183.5 (95% CI 100.1-266.9) days (p < 0.001). After adjusting for the type of thrombolytic agent, use of adjunct thrombectomy device, cutting balloon, drug-coated balloon, and stent graft, SEP remained a significant factor associated with longer thrombosis-free patency (HR 0.166: 95% CI 0.070-0.392, p < 0.001).

DISCUSSION

SEP appears to be a feasible and safe thromboprophylaxis method to improve thrombosis-free patency for AV access with recurrent thrombosis.

Endovascular salvage of failing arterio-venous fistulas utilising sirolimus eluting balloons: Six months results from the ISABELLA trial

BACKGROUND

Aim of this pilot clinical study was to evaluate the safety and efficacy of the Selution Sustained Limus Release (SLR)™ sirolimus-eluting balloon (SEB) for improving failing arterio-venous fistulas (AVF) patency in Asian haemodialysis patients.

METHODS

Prospective single-centre, multi-investigator, non-consecutive, non-blinded single arm trial. Forty end-stage renal failure Asian patients with a dysfunctional AVF underwent SEB angioplasty between May and November 2020. All stenotic lesions were prepared with high pressure non-compliant balloon angioplasty prior to SEB angioplasty. Endpoints of interest included target lesion primary patency and circuit access patency and safety through 30 days. All patients received dual antiplatelet therapy for 1 month and were followed up with Duplex ultrasound at 6 months.

RESULTS

There was one subject dropout so final n = 39 patients (mean age 65.0 ± 11.9; males = 26 (66.7%)) and n = 43 target lesions treated. Main indication for intervention was dropping access flow (24/39; 61.5%) and most common target lesion was in the juxta-anastomosis (24/43; 54.5%). There was 100% technical and procedural success. There were no adverse events related to the SEB. Target lesion primary patency rates at 3 and 6 months were 39/41 (95.1%) and 28/39 (71.8%) respectively. Access circuit patency rates at 3 and 6 months were 35/37 (94.6%) and 22/35 (62.9%) respectively. There were 3 (7.7%) deaths all attributable to patients' underlying co-morbidities.

CONCLUSIONS

Fistuloplasty using the novel Selution SLR™ SEB for dysfunctional AVF circuits seems a safe and effective modality in Asian haemodialysis patients at 6 months but larger randomised controlled studies are required now to determine its true efficacy against plain balloon angioplasty.

Ranger™ paclitaxel-coated balloon versus conventional balloon angioplasty for treatment of failing arteriovenous fistulas and grafts in haemodialysis patients: A retrospective cohort study

BACKGROUND

Aim was to compare the safety and patency efficacy outcomes between Ranger™ paclitaxel-coated balloon (PCB)- versus conventional balloon angioplasty (POBA) in the treatment of haemodialysis access-related conduit stenosis.

METHODS

Retrospective single-centre, multi-investigator, consecutive, double-arm comparative cohort study. About 130 end-stage renal failure Asian patients with dysfunctional arteriovenous fistula (AVF) or arteriovenous graft underwent PCB or POBA fistuloplasty between November 2018 and June 2020. All stenotic lesions were prepared with high pressure non-compliant balloon angioplasty prior to PCB angioplasty. All patients received at least one antiplatelet agent for 3 months duration post procedure.

RESULTS

Mean age was 66.0 ± 10 years and 79/130 (61%) were males. PCB arm (n = 65) versus POBA arm (n = 65). Majority were AVFs circuits (122/130, 94%). Main indication for intervention was dropping access flow (98/130, 76%). About 172 lesions were treated (56% POBA, 44% PCB), and the juxta-anastomosis (JAS) was the main target lesion (87/172, 51%). There were no significant differences in safety outcomes (30-day adverse events, access thrombosis, abandoned AVF and death) between treatment groups. Mean time to target lesion reintervention (TLR) was longer in PCB-treated lesions (7.1 ± 2.7 vs 5.8 ± 3.2 months, p = 0.03), especially amongst recurrent lesions (7.3 ± 2.4 vs 5.7 ± 3.2, p = 0.02). Mean time to circuit reintervention was also longer in PCB-treated circuits (6.9 ± 2.8 vs 5.8 ± 3.7months, p = 0.04). There were 16 deaths (12%), all attributed to patient's underlying comorbidities.

CONCLUSIONS

Fistuloplasty with Ranger™ PCB for failing arteriovenous circuits in end-stage renal failure patients, is a safe and efficacious modality compared to POBA in terms of longer freedom from TLR.

Use of the helical SUPERA™ stent and Passeo-18 Lux™ drug-coated balloon to treat recurrent cephalic arch stenosis for dysfunctional brachiocephalic fistulas: 1 year results of the Arch V SUPERA-LUX study

BACKGROUND

Aim of Arch V SUPERA-LUX was to evaluate the safety and efficacy of the combination therapy of SUPERA™ (Abbott Vascular, Santa Clara, CA, USA) helical stent implantation and Passeo-18 Lux™ (Biotronik Asia Pacific Pte Ltd, Singapore) drug coated balloon (DCB) elution to treat recurrent cephalic arch stenosis (CAS) in the setting of AV access dysfunction.

METHODS

Investigator-initiated, single-center, single-arm prospective pilot study of 20 end-stage renal failure Asian patients with a dysfunctional brachiocephalic fistula. All had symptomatic recurrent CAS within 6 months of prior intervention. The lesion was pre-dilated with a standard high-pressure balloon (Biotronik Passeo-35 HP balloon). The DCB (Passeo-18 Lux™) is subsequently inflated and the SUPERA™ stent deployed to sit 2 mm distal to the cephalic arch and covering the CAS but within the DCB zone. All patients were prescribed dual antiplatelet therapy for 3 months and followed up with Duplex ultrasound at 6- and 12-months.

RESULTS

There were 9 (45%) males and mean age was 67 ± 11.0 years. Mean time from prior procedure was 113 ± 68 days and main indication for reintervention was high venous pressure (9/20, 45%). Technical success was 100% and there were no peri-procedural complications related to either stent or DCB deployment. Target lesion primary patency at 6- and 12-months was 10/18 (55%) and 5/16 (31%), respectively. Mean time to target lesion re-intervention was 170 ± 82 days. Circuit access patency was 8/18 (44%) and 2/16 (13%) at 6- and 12-months respectively and mortality was 3/20 (15%) attributed to the patients' underlying co-morbidities.

CONCLUSION

Dual prong strategy of using SUPERA™ stenting and Passeo-18 Lux™ drug elution for recurrent CAS, although safe, was no more efficacious than conventional balloon angioplasty or stenting alone. Development of an intense inflammatory reaction within the stent led to reinterventions of a number of cases with suboptimal results.

SIroliMus coated angioPlasty versus plain balloon angioplasty in the tREatment of dialySis acceSs dysfunctION (IMPRESSION): study protocol for a randomized controlled trial

Background

Percutaneous transluminal angioplasty is the current standard treatment for arteriovenous fistula (AVF) stenosis. The mid- and long-term patency with plain balloon angioplasty (PBA) is however far from satisfactory. While paclitaxel-coated balloon angioplasty has been shown to be superior to PBA, concern over its safety profile has recently arisen after a reported possible increased mortality risk with a meta-analysis of large lower limb studies. An angioplasty balloon with a new type of drug coating, the sirolimus-coated balloon (SCB), has been proven to improve patency in the coronary arteries. However, its effect on AV access has yet to be studied.

Methods/design

This is an investigator-initiated, prospective, multicenter, double-blinded, randomized controlled clinical trial to assess the effectiveness of SCB compared to PBA in improving the patency of AVF after angioplasty. A total of 170 patients with mature AVF that requires PTA due to AVF dysfunction will be randomly assigned to treatment with a SCB or PBA at a 1:1 ratio, stratified by location of AVF and followed up for up to 1 year. The inclusion criteria include [1] adult patient aged 21 to 85 years who requires balloon angioplasty for dysfunctional arteriovenous fistula [2]; matured AVF, defined as being in use for at least 1 month prior to the angioplasty; and [3] successful angioplasty of the underlying stenosis with PBA, defined as less than 30% residual stenosis on digital subtraction angiography (DSA) and restoration of thrill in the AVF on clinical examination. The exclusion criteria include thrombosed or partially thrombosed access circuit at the time of treatment, presence of symptomatic or angiographically significant central vein stenosis that requires treatment with more than 30% residual stenosis post angioplasty, and existing stent placement within the AVF circuit. The primary endpoint of the study is access circuit primary patency at 6 months. The secondary endpoints are target lesion primary patency; access circuit-assisted primary patency; access circuit secondary patency at 3, 6, and 12 months; target lesion restenosis rate at 6 months; total number of interventions; complication rate; and cost-effectiveness. The trial is supported by Concept Medical.

Discussion

This study will evaluate the clinical efficacy and safety of SCB compared to PBA in the treatment of AVF stenosis in hemodialysis patients.

Trial registration

ClinicalTrials.govNCT04409912. Registered on 1 June 2020

Treatment of cephalic arch stenosis in dysfunctional arteriovenous fistulas with paclitaxel-coated versus conventional balloon angioplasty

Background

Treatment of cephalic arch stenosis (CAS) with standard plain old balloon angioplasty (POBA) in dysfunctional arteriovenous fistulas (AVF), is associated with early re-stenosis and higher failure rates compared to other lesions. Paclitaxel-coated balloons (PCB) may improve patency rates. This is a retrospective cohort study. Patients who underwent POBA or PCB for CAS over a 3-year period were included. Outcomes compared were circuit primary patency rates (patency from index procedure to next intervention), circuit primary assisted-patency rates (patency from index procedure to thrombosis), and target lesion (CAS) patency rates (stenosis > 50%) at 3, 6 and 12 months.

Results

Ninety-one patients were included. Sixty-five (71.4%) had POBA, while 26 (28.6%) had PCB angioplasty. There were 62 (68.1%) de-novo lesions. CAS was the only lesion that needed treatment in 24 (26.4%) patients. Circuit primary patency rates for POBA versus PCB groups were 76.2% vs. 60% (p = 0.21), 43.5% vs. 36% (p = 0.69) and 22% vs. 9.1% (p = 0.22) at 3, 6 and 12-months respectively. Circuit assisted-primary patency rates were 93.7% vs. 92% (p = 1.00), 87.1% vs. 80% (p = 0.51) and 76.3% vs. 81.8% (p = 0.77), whilst CAS target lesion intervention-free patency rates were 79.4% vs. 68% (p = 0.40), 51.6% vs. 52% (p = 1.00) and 33.9% vs. 22.7% (p = 0.49) at 3, 6 and 12-months respectively. Estimated mean time to target lesion intervention was 215 ± 183.2 days for POBA and 225 ± 186.6 days for PCB (p = 0.20).

Conclusion

Treatment of CAS with PCB did not improve target lesion or circuit patency rates compared to POBA.

Outcomes of arteriovenous fistula in elderly patients on maintenance haemodialysis

BACKGROUND

The optimal vascular access strategy in elderly patients receiving haemodialysis (HD) remains controversial. We aim to report the outcomes of arteriovenous fistula (AVF) in elderly patients initiated on maintenance HD in our centre.

METHODS

Medical records of 688 incident patients initiated on HD from 2010 to 2012 in a tertiary centre were retrospectively reviewed. Patients' characteristics and AVF outcomes were compared among those < 65 years (non-elderly), ≥ 65-75 years (early elderly) and ≥ 75 years (late elderly).

RESULTS

There were 418 non-elderly, 184 early elderly and 86 late elderly patients. There is a higher proportion of brachiocephalic and brachiobasilic fistula created in the late elderly (24.9% vs. 37.0% vs. 41.8%, p = 0.001). The outcomes of accesses created were comparable in the 3 age groups with similar proportions of functional AVFs (80.4% vs. 79.3% vs. 75.6%, p = 0.832) and comparable 1-, 3- and 5-year primary and secondary patency rates (p = 0.351 and 0.282, respectively). However, a longer maturation time (2.78 vs. 2.86 vs. 3.72 months, p = 0.010) and a higher mean number of interventions to assist maturation of the first AVF were required in late elderly patients (0.19 vs. 0.22 vs. 0.35, p = 0.014). Following AVF creation, median patient survival in the non-elderly, early and late elderly was 65.2 vs. 55.1 vs. 49.8 months respectively.

CONCLUSION

AVFs created in elderly patients have comparable outcomes compared to non-elderly patients although more interventions are required to assist maturation with a longer maturation time necessitating early access creation to allow for time needed due to maturation delay.

Single Asian Center Experience Using the Flixene™ Early Cannulation Graft for Hemodialysis Access Creation

BACKGROUND

The aim of this study was to review the efficacy of the Flixene™ (Atrium™, Hudson, NH, USA) hemodialysis arterio-venous graft (AVG) in a multiethnic Asian cohort of patients with end-stage renal failure (ESRF). Primary outcome was graft primary patency rate and secondary end points included graft usability, time to cannulation, reinterventions required for access salvage, complications, and patient mortality.

METHODS

Single-center, single-arm, multi-investigator nonrandomized retrospective study. Patients with ESRF who underwent Flixene™ graft implantation over a two-year period (January 2017 - December 2018) were included to allow at least one-year follow-up. Demographics, procedural and follow-up data were collected from the hospital electronic medical records.

RESULTS

About 48 patients (49 AVG) were included. There were 24 (50%) men; mean age 63.7 (IQR 58.2-71.3) years. Technical success rate was 45/49 (91.8%); 4/49 (8.2%) AVG created did not reach cannulation. 11/49 (22.4%) and 28/49 (57.1%) achieved cannulation within 1 and 2 weeks, respectively. 6- and 12- month primary patencies were 33.5% and 19.6%, respectively. Primary-assisted patency rates were 46.6% and 29.6% at the same time intervals. Secondary patency rate was 77.6% and 63.9% at 6 and 12 months, respectively. There were 6 (12.2%) graft infections requiring explant and one-year mortality was 14%.

CONCLUSIONS

Our experience with the Flixene™ early cannulation graft is comparable with other AVGs in terms of patency and infection rates. However, early cannulation rates are lower than in other case series.

Single-Center Prospective Pilot Study of Sirolimus Drug-Coated Balloon Angioplasty in Maintaining the Patency of Thrombosed Arteriovenous Graft

PURPOSE

To investigate the use of a sirolimus drug-coated balloon (DCB) in the management of a thrombosed arteriovenous graft (AVG).

MATERIALS AND METHODS

A single-center prospective pilot study was conducted between October 2018 and October 2019. Twenty patients (age = 67.0 years ± 10; male = 35%; mean time on dialysis = 31 months) with thrombosed upper limb AVG were enrolled. After successful pharmacomechanical thrombectomy and adequate treatment of the graft vein junction, sirolimus DCB angioplasty was performed at the graft vein junction. The patients were followed-up for 6 months, and all adverse events occurring during the study period were recorded.

RESULTS

The primary circuit patency rates at 3 and 6 months were 76% and 65%, respectively, while the assisted-primary circuit patency rates at 3 and 6 months were 82% and 65%, respectively. The 3- and 6-month secondary circuit patency rates were 88% and 76%, respectively. Using Kaplan-Meier analyses, the estimated mean primary, assisted-primary, and secondary patencies were 285 days (95% confidence interval (CI) = 194-376 days), 319 days (95% CI = 221-416 days), and 409 days (95% CI = 333-485 days). No adverse event directly related to sirolimus DCB use was observed.

CONCLUSIONS

The results of this pilot study suggest that the application of sirolimus DCB at the graft vein junction after the successful thrombectomy of AVG may be a feasible option to improve patency outcomes.

Effect of short-term low molecular weight heparin on patency following successful salvage of arteriovenous access with recurrent thrombosis

AIM

This study aims to investigate the effect of low molecular weight heparin (LMWH) in maintaining the patency of arteriovenous (AV) access with recurrent thrombosis.

METHODS

Following successful thrombectomy, 66 patients with recurrent thrombosis were included in the study. The primary, assisted primary and secondary patency rates of patients who received LMWH (n = 24) were compared with those who did not receive anticoagulant (n = 42) using Kaplan-Meier analysis. Cox-regression analysis was performed to investigate potential predictors of patency rates.

RESULTS

The mean dose of enoxaparin used was 40 ± 13.1 mg or 0.74 ± 0.2 mg/kg daily for a median duration of 14 (IQR 7,28) days. The mean trough anti-Xa concentrations measured after two doses of LMWH was 0.17 ± 0.13 IU/mL. Kaplan-Meier analyses for mean primary, assisted primary and secondary patency rates of LMWH vs no anticoagulation groups were 149 (95% CI: 91 - 207) vs 87 (95% CI: 42-132) days (P < .006), 230 (95% CI: 142-320) vs 107 (95% CI: 62-150) days (P = .01) and 438 (299-579) vs 294 (95% CI: 197-392) days (P = .08) respectively. LMWH remained a significant protective predictor of primary (HR: 0.49; 95% CI: 0.25-0.86; P = .02) and assisted primary patency rates (HR: 0.51; 95% CI: 0.27-0.98; P = .04) after adjusting for patient age, access age, type of AV access, presence of peripheral vascular disease and haemoglobin levels.

CONCLUSION

LMWH may improve short and mid-term patency rates for AV accesses with recurrent thrombosis.

Early (6 months) results of a pilot prospective study to investigate the efficacy and safety of sirolimus coated balloon angioplasty for dysfunctional arterio-venous fistulas: MAgicTouch Intervention Leap for Dialysis Access (MATILDA) Trial

Background

The aim of this pilot study was to evaluate the safety and efficacy of the MagicTouch™ sirolimus-coated balloon (SCB) catheter (Concept Medical Inc., Tampa, FL, US) on improving the patency of failing arterio-venous fistulas (AVF) with de novo and recurrent stenoses. MATILDA reports early outcomes at 3- and 6 months post intervention.

Methods

Single-centre, single-arm prospective pilot study of 33 (18 males; mean age 64.7±11.6 years) end-stage renal failure Asian patients with a dysfunctional AVF, who underwent SCB angioplasty between May 2019-January 2020. All procedures were performed under local anaesthetic without sedation and as day surgery. All patients were prescribed dual antiplatelet therapy for 3 months and followed up with Duplex ultrasound at 3 and 6 months.

Results

47 stenotic target lesions treated and 24/33 (72.7%) patients were for restenosis. Main indications for intervention was low/dropping access flow (21/33; 63.6%) and most common target lesion was in the juxta-anastomosis (19/47; 40.4%). There was 100% technical and procedural success. There were no peri-procedural complications related to the SCB. The target lesion primary patency rates at 3 and 6 months were 46/47 (97.9%) and 29/35 (82.9%) respectively. Circuit access patency rates at 3 and 6 months were 31/33 (93.9%) and 17/25 (68%) respectively. There was one (2.9%) death at 6 months and 4/33 (12.1%) overall to date, all from patients’ underlying co-morbidities.

Conclusions

SCB angioplasty for dysfunctional AVF circuits is a safe and efficacious modality in Asian haemodialysis patients at six months comparable if not better than the paclitaxel data reported to date in the literature.

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.

Study protocol of a pilot study on sirolimus-coated balloon angioplasty in salvaging clotted arteriovenous graft

Background

In arteriovenous graft (AVG) for haemodialysis, the primary cause of failure is venous stenosis of the graft-vein junction from neointimal hyperplasia (NIH), resulting in thrombosis. While interventions to salvage clotted AVG are known to have high clinical success rates, long-term patency rates have been suboptimal. Drug-coated balloon (DCB) has been used to treat stenosed arteriovenous access in recent years with encouraging results but data on its effect in clotted AVG is unavailable.

Methods

This is an investigator-initiated, single-center, single-arm prospective pilot study to determine the safety and outcome of the sirolimus-coated balloon (SCB) in the salvage of thrombosed AVG. Twenty patients who undergo successful percutaneous thrombectomy will receive treatment with SCB at the graft vein junction. The patients will be followed-up for 6-months. The primary endpoint is the patency rates at 3-month while the secondary endpoints are the patency rates and the number of interventions needed to maintain patency at 6-month.

Discussion

Unremitting efforts have been made to prolong the patency of AV accesses over the years. DCB angioplasty combines mechanical and biological treatment for vascular stenosis. Sirolimus, being a cystostatic anti-proliferative agent, has been successfully used in coronary artery interventions. As the primary pathology of vascular stenosis in the dialysis circuit is neointimal hyperplasia, the use of sirolimus in balloon angioplasty may be effective. With this prospective study, we evaluate the efficacy and safety of SCB in patients with clotted AVG.

Trial registration

ClinicalTrials.gov Identifier: NCT03666208 on 11 September 2018.

Mechanically-induced osteophyte in the rat knee

OBJECTIVES

Osteophytes are common anatomical signs of advanced osteoarthritis. It remains unclear whether they develop from physio-molecular, and/or mechanical stimuli. This study examined the effects of mechanical impact on the knee joint periosteum leading to osteophyte formation.

DESIGN

Eighteen mature rats received one single impact load of 53 N (30 MPa) to the periosteum of the experimental medial femoral condyles. Contralateral knees were used as controls. Animals were sacrificed at 24 h, 3, 6 and 9 weeks post-impact. Distal femurs were harvested and prepared for histology. Hematoxylin and Eosin, and Masson's trichrome stained slides were examined by light microscopy. Nuclear density was quantified to assess the tissue reaction.

RESULTS

24 h: The synovium membrane, fibrous and cambium periosteum were damaged. Blood infiltration pooled in the impacted medial collateral ligament (MCL) region. Week 3: A cartilaginous tissue spur, chondrophyte, was found in every rat at the impacted site of the MCL. Chondrophytes were composed of fibrocartilage and cartilage matrix, with signs of cartilage mineralization and remodelling activity. Week 6: Chondrophytes presented signs of more advanced mineralisation, recognized as osteophytes. Week 9: Osteophytes appeared to be more mineralized with almost no cartilage tissue.

CONCLUSIONS

Osteophytes can be induced with a single mechanical impact applied to the periosteum in rat knees. These data indicate that a moderate trauma to the periosteal layer of the joint may play a role in osteophyte development.

[Association between single nucleotide polymorphism in promoter region of SIRT1 gene and senile degenerative heart valvular disease]

Objective: To investigate the correlation between single nucleotide polymorphisms (SNPs) of SIRT1 gene promoter sequence and senile degenerative heart valvular disease (SDHVD). Methods: A total of 236 SDHVD patients and 285 healthy controls who visited the Affiliated Hospital of Jining Medical University between February 2012 and October 2016 were enrolled. SNPs of SIRT1 gene promoter were detected by Sanger sequencing. Typing and correlation were analyzed by χ(2) test and Logistic regression analysis. Haplotype and linkage disequilibrium were analyzed by Haploview4.2 software and SHEsis online software. The effect of SNPs on the binding of transcription factors to SIRT1 gene promoter was analyzed by electrophoretic mobility shift assay(EMSA). The transcription factors affected by SNPs were predicted by Transfac online software. Results: The frequency distribution of GG genotype of rs3740051 in the SDHVD group was significantly higher than that in the control group (χ(2)=4.855, P=0.028). There was a correlation between GG genotype of the rs3740051 and SDHVD. After adjusting for age, the risk of SDHVD in the carrier of GG genotype was 3.079 times higher than that of AA genotype(OR=3.079, 95%CI: 1.156-8.201, P=0.024). The five SNPs (rs3740051, rs932658, rs35995735, rs3740053 and rs2394443) showed strong linkage disequilibrium(D'>0.8). The haplotype analysis of the five SNPs (haplotype frequency<0 was ignored in the analysis) showed that 11 haplotypes (P<0.05) were formed, and the frequency of *A**C, AA**C, *AG*C, AAG*C, AA*AC, *AGAC and AAGAC in SDHVD group were significantly higher than that in control group (P<0.05, OR>1, 95%CI does not contains 1). EMSA showed that the color of the binding bands incubated by wild type probe and nucleoprotein was darker than that incubated by DNA sequence variation probe and nucleoprotein. Conclusion: The GG genotype of rs3740051 is associated with SDHVD and may be a risk genotype for SDHVD. The haplotype AC (across rs932658 and rs2394443) may be a dangerous haplotype of SDHVD. rs3740051 may affect the occurrence and development of SDHVD by interfering with the binding of FOXC protein to SIRT1 gene promoter.

Current state of vascular access in Singapore

This article described the current state of vascular access management for patients with end-stage renal disease in Singapore. Over the past 10 years, there has been a change in the demographics of end-stage renal disease patients. Aging population and the increase in prevalence of diabetes mellitus has led to the acceleration of chronic kidney disease and increase in incidence and prevalence of end-stage renal disease. Vascular access care has, therefore, been more complicated, with the physical, psychological, and social challenges that occur with increased frequency in elderly patients and patients with multiple co-morbidities. Arteriovenous fistula and arteriovenous graft are created by vascular surgeons, while maintenance of patency of vascular access through endovascular intervention has been a shared responsibility between surgeons, interventional radiologists, and interventional nephrologists. Pre-emptive access creation among end-stage renal disease patients has been low, with up to 80% of new end-stage renal disease patients being commenced on hemodialysis via a dialysis catheter. Access creation is exclusively performed by a dedicated vascular surgeon with arteriovenous fistula success rate up to 78%. The primary and cumulative patency rates of arteriovenous fistula and arteriovenous graft were consistent with the results from many international centers. Vascular access surveillance is not universally practiced in all dialysis centers due to its controversies, in addition to the cost and the limited availability of equipment for surveillance. Timely permanent access placement, with reduced dependence on dialysis catheters, and improved vascular access surveillance are the main areas for potential intervention to improve vascular access management.

Outcomes of endovascular salvage of clotted arteriovenous access and predictors of patency after thrombectomy

OBJECTIVE

This study aimed to report the outcomes of endovascular salvage of clotted arteriovenous (AV) accesses and to determine potential predictors of poor patency rates after thrombectomy.

METHODS

Records of hemodialysis patients who underwent endovascular salvage of clotted AV access were reviewed retrospectively. Technical and clinical success rates, complication rates, and 3- and 6-month patency rates were determined. Multivariate analysis was performed to determine the predictors of patency after thrombectomy.

RESULTS

A total of 294 patients underwent endovascular salvage of clotted AV access during the study period; 156 patients had arteriovenous fistula, whereas the remaining 138 were arteriovenous grafts (AVGs). The technical and clinical success rates were 96.3% and 93.2%; the major and minor complication rates were 0.7% and 9.9%. Post-thrombectomy primary, assisted primary, and secondary patency rates were 62.9%, 76.2%, and 77.6% at 3 months and 43.9%, 59.5%, and 61.6% at 6 months. The patency rates were significantly better for arteriovenous fistula than for AVG except for 6-month assisted primary and secondary patency. Multivariate Cox regression analysis showed that prior thrombosis within 90 days was significantly associated with loss of primary patency (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.21-2.98; P < .01), assisted primary patency (HR, 2.42; 95% CI, 1.42-4.13; P < .01), and secondary patency (HR, 2.52; 95% CI, 1.40-4.53; P < .01). Having an AVG was also negatively associated with primary patency.

CONCLUSIONS

Most clotted AV accesses can be salvaged by endovascular technique. Recurrent thrombosis within 90 days is associated with poor short- and long-term patency even after successful endovascular reinterventions.

Validation of the failure to maturation equation and proposal for a novel scoring system for arteriovenous fistula maturation in multiethnic Asian haemodialysis patients

INTRODUCTION

A successful arteriovenous fistula is essential for effective haemodialysis. We aim to validate the existing failure to maturation equation and to propose a new clinical scoring system by evaluating arteriovenous fistula success predictors.

METHODS

Data of end-stage renal disease patients initiated on haemodialysis from January 2010 to December 2012 were retrospectively obtained from medical records with follow-up until 1 January 2014. Application of the failure to maturation equation was evaluated. A nomogram was developed using arteriovenous fistula success predictors and was calibrated with a bootstrapping technique.

RESULTS

A total of 694 patients were included with mean duration of follow-up of 2.3 years. Arteriovenous fistula maturation was achieved by 542 patients (78%). Comparing our cohort with the failure to maturation cohort, there were statistically significant differences in mean age, ethnicity and presence of diabetes mellitus. The failure to maturation equation failed to predict arteriovenous fistula outcomes with area under the curve performance of 0.519 on a receiver operating characteristic curve. Multivariate logistic regression showed that Malay patients (odds ratio = 0.628; 95% confidence interval = 0.403-0.978; p < 0.05) and patients requiring preoperative vein mapping (odds ratio = 0.601; 95% confidence interval = 0.410-0.883; p < 0.01) had a lower chance of arteriovenous fistula success, whereas male gender (odds ratio = 1.526; 95% confidence interval = 1.040-2.241; p < 0.05) and presence of postoperative good thrill (odds ratio = 3.137; 95% confidence interval = 2.127-4.625; p < 0.0001) had a higher chance of arteriovenous fistula success. The derived nomogram predicted arteriovenous fistula success (odds ratio = 1.030; 95% confidence interval = 1.022-1.038; p < 0.0001) with the area under the curve of 0.695 on a receiver operating characteristic curve and an adequacy index of 99.86% (p < 0.0001).

CONCLUSION

The failure to maturation equation was not validated in our cohort. The clinical utility of our proposed arteriovenous fistula scoring system requires external validation in larger studies.

Comparison of Clinical Presentation and Outcomes of Peritonitis in the Elderly and Younger Peritoneal Dialysis Patients

Background

The incidence of elderly patients receiving peritoneal dialysis (PD) has increased. This study aimed to examine the clinical presentation and outcomes of peritonitis in elderly PD patients compared with younger PD patients.

Methods

This single-center, retrospective, observational cohort study included all adult PD patients who developed peritonitis between January 2011 and December 2014. Elderly was defined as ≥ 65 years old at PD initiation. The primary outcome was medical cure, defined as a peritonitis episode cured by antibiotics without being complicated by catheter removal, transfer to hemodialysis (HD), relapsing peritonitis, or death. The secondary outcomes were clinical manifestations (fever, cloudy dialysate) and complications (catheter removal, transfer to HD, relapse, hospitalization, and mortality). Peritonitis outcomes were compared using multivariable logistic regression.

Results

Overall, 377 peritonitis episodes occurred in 247 patients. Of these, 126 episodes occurred in 79 elderly patients and 251 episodes occurred in 168 younger patients. Baseline demographic data were comparable between the 2 groups, except that elderly patients were significantly more likely to have diabetes mellitus (66% vs 46%), diabetic nephropathy (55% vs 39%), and a lower serum albumin than younger patients. Medical cure was comparable between the 2 groups (71% vs 72%, respectively, p = 0.67, adjusted odds ratio [AOR] 0.89, 95% confidence interval [CI]: 0.52 – 1.53). Compared with younger patients, elderly patients experiencing peritonitis had lower odds of fever (OR 0.53, 95% CI: 0.30 – 0.94), cloudy dialysate (OR 0.45, 95% CI: 0.23 – 0.88), and catheter removal (AOR 0.50, 95% CI: 0.26 – 0.98), but similar odds of transfer to HD (AOR 0.70, 95% CI: 0.32 – 1.51), relapse (AOR 1.57, 95% CI: 0.46 – 5.40), hospitalization (AOR 1.55, 95% CI: 0.52 – 4.56), and all-cause mortality (AOR 1.88, 95% CI: 0.83 – 4.26).

Conclusions

Compared with younger patients, elderly PD patients with peritonitis achieved similar medical cure rates, a lower catheter removal rate, and comparable rates of HD transfer, relapse, hospitalization, and death. Elderly PD patients experiencing peritonitis were less likely to present with fever or cloudy dialysate.

Comparison of alteplase and urokinase for pharmacomechanical thrombolysis of clotted hemodialysis access

BACKGROUND

Percutaneous pharmacomechanical thrombolysis is increasingly used to salvage thrombosed hemodialysis access. We aim to evaluate the effectiveness of alteplase compared to urokinase in percutaneous pharmacomechanical thrombolysis clotted access.

METHODS

Records of patients who underwent pharmacomechanical thrombolysis at Interventional Nephrology Suite in a tertiary teaching hospital from 1 January 2016 to 31 December 2016 were reviewed. Technical and clinical success rates, thrombosis-free and cumulative survivals, procedure time, and radiation dose imparted to patients were compared for pharmacomechanical thrombolysis with urokinase versus alteplase.

RESULTS

A total of 122 incident patients underwent pharmacothrombolysis (n = 53 for urokinase, n = 69 for alteplase) during the study period. The mean dose of urokinase and alteplase used was 176,897 ± 73,418 units and 3.7 ± 0.8 mg, respectively. Pharmacomechnical thrombolysis using urokinase versus alteplase has similar technical success rate (98.1% vs 97.1%, p = 0.599), clinical success rate (88.7% vs 97.1%, p = 0.068), complication rate (9.4% vs 13.0%, p = 0.373), and primary patency rates at 3 months (57.1% vs 70.1%, p = 0.106). Thrombosis-free survivals of the vascular access were 113.2 (35.3, 196) days versus 122 (84, 239) days (p = 0.168). Cumulative survivals were 239 (116, 320) vs 213 (110.5, 316.5) days (p = 0.801). Procedure time, fluoroscopy time, skin dose, and dose were significantly lower for pharmacomechanical thrombolysis using alteplase compared to urokinase (p = 0.045, p < 0.0001, p = 0.006, p = 0.001, respectively). Stenting was found to be associated with successful dialysis following thrombolysis on univariate analysis (odds ratio: 9.167, 95% confidence interval: 1.391-19.846, p = 0.021), although this was no longer significant in multivariate analysis (p = 0.078).

CONCLUSION

Alteplase is an effective and safe alternative to urokinase for pharmacomechanical thrombolysis of clotted vascular access.

A pilot study on adjunctive use of parametric colour-coded digital subtraction angiography in endovascular interventions of haemodialysis access

Background

Two-dimensional digital subtraction angiography (DSA) is the gold standard for angiographic evaluation of dysfunctional haemodialysis access. We aim to investigate the utility of parametric colour coded DSA in providing hemodynamic analysis during haemodialysis access interventions.

Methods

We retrospectively studied 20 patients who underwent access intervention and applied parametric colour-coding on selected DSA acquisitions before and after percutaneous transluminal angioplasty (PTA). The difference in time to peak (dTTP) contrast enhancement and time attenuation curve (TAC) of pre- and post-stenotic regions of interest (ROIs) were obtained and compared after treatment.

Results

Improvements were seen in mean percent of stenosis after PTA (p < 0.0001) for all cases. Median dTTP improved from 0.52 (IQR 0.26, 0.8) to 0.25 (IQR 0, 0.26) seconds (p = 0.001). Median 50% contrast washout time improved from 0.77 (IQR 0.39, 1.17) to 0.42 (IQR 0.23, 0.59) seconds (p = 0.031). Significant correlation was seen for dTTP vs. percent of stenosis (r = 0.723, p = 0.043) pre-PTA and for change in dTTP vs. percent change in stenosis post-PTA (r = 0.786, p = 0.021) for inflow lesions. Such correlation was however not seen in outflow lesions.

Conclusions

Adjunctive use of parametric colour-coded DSA may provide potentially useful hemodynamic information during vascular access interventions. Larger prospective studies are needed to validate our findings.

Low efficacy of delthamethrin-treated net against Singapore Aedes aegypti is associated with kdr-type resistance

There has been a worldwide surge in the number and severity of dengue in the past decades. In Singapore, relentless vector control efforts have been put in to control the disease since the 1960's. Space spraying, fogging, chemical treatment and source reduction are some commonly used methodologies for controlling its vectors, particularly Aedes aegypti. Here, as we explored the use of a commercially available delthamethrin-treated net as an alternative strategy and the efficacy of the treated net was found to be limited. Through bioassays and molecular studies, the failure of the treated net to render high mortality rate was found to be associated with the knockdown resistance (kdr) mutation. This is the first report of kdr- mutations in Singapore's Ae. aegypti. At least one point mutation, either homozygous or heterozygous, at amino acid residue V1016G of DIIS6 or F1269C of DIIIS6 was detected in 93% of field strains of Ae. aegypti. Various permutations of wild type and mutant amino acids of the four alleles were found to result in varying degree of survival rate among local field Ae. aegypti when exposed to the deltamethrin treated net. Together with the association of higher survival rate with the presence of both V1016G and F1269C, the data suggest the role of these mutations in the resistance to the deltamethrin. The high prevalence of these mutations were confirmed in a country wide survey where 70% and 72% of the 201 Ae. aegypti analysed possessed the mutations at residues 1016 and 1269 respectively. The highest mutated frequency combination was found to be heterozygous alleles (VG/FC) at both residues 1016 and 1269 (37.8%), followed by homozygous mutation at allele 1269 (24.4%) and homozygous mutation at allele 1016 (22.9%). The kdr- type of resistance among the vector is likely to undermine the effectiveness of pyrethroids treated materials against these mosquitoes.

The effect of moving point of contact stimulation on chondrocyte gene expression and localization in tissue engineered constructs

Tissue engineering is a promising approach for articular cartilage repair. However, using current technologies, the developed engineered constructs generally do not possess an organized superficial layer, which contributes to the tissue's durability and unique mechanical properties. In this study, we investigated the efficacy of applying a moving point of contract-type stimulation (MPS) to stimulate the production of a superficial-like layer in the engineered constructs. MPS was applied to chondrocyte-agarose hydrogels at a frequency of 0.5, 1 or 2 Hz, under a constant compressive load of 10 mN for durations between 5 and 60 min over 3 consecutive days. Expression and localization of superficial zone constituents was conducted by qRT-PCR and in situ hybridization. Finite element modeling was also constructed to gain insight into the relationship between the applied stimulus and superficial zone constituent expression. Gene expression of superficial zone markers were affected in a frequency dependent manner with a physiologic frequency of 1 Hz producing maximal expression of PRG4, biglycan, decorin and collagen II. In situ hybridization revealed that localization of these markers predominantly occurred at 500-1000 μm below the construct surface which correlated to sub-surface strains between 10 and 25% as determined by finite element modeling. These results indicate that while mechanical stimuli can be used to enhance the expression of superficial zone constituents in engineered cartilage constructs, the resultant subsurface loading is a critical factor for localizing expression. Future studies will investigate altering the applied stimulus to further localize superficial zone constituent expression at the construct surface.

Noninvasive investigation of asymmetrically conjoined tripus twins with features of rachipagus, parapagus dicephalus, and cephalopagus

A hypothetical mechanism for conjoined twinning postulated by Spencer ([2003] Developmental Malformations and Clinical Implications, Baltimore: Johns Hopkins University Press, p 1-476) suggests that, after separation, monovular twins fuse in one of eight predictable homologous sites. The tripus fetal specimen under study embodies characteristics of three types therefore preventing it from classification into a simple variant of any one of the eight twin types described by Spencer. The aim of this study was to reveal internal structural anomalies of the fetal specimen by using magnetic resonance imaging and computerized tomography. Dorsally appended to the primary twin is a secondary head mass (brain tissue and ocular globe) and two spinal columns converging at T4/T5, suggesting rachipagus twinning. The ventral orientation of the secondary twin's (right lateral) lower limb suggests parapagus twinning. The caudal divergence of the spinal columns and the presence of a secondary hemipelvis, separate from the primary pelvis, suggest cephalopagus twinning. Measurements of the long bones indicate a gestational age of ∼20-23 weeks. Secondary malformations of the primary fetal body include anencephaly, cleft palate, renal agenesis, decreased left ventricular outflow, and a prematurely terminating descending aorta. This study demonstrates the possibility of using current imaging techniques to study very old, formalin-preserved human material for documentation and scientific discussion without destroying the specimen, thus keeping it intact for posterity.

A potential role for the endothelin ETA receptor in salt-sensitive hypertension of the proANP gene-disrupted mouse

We have previously shown that the partial disruption of the gene for atrial natriuretic peptide (ANP) results in a salt-sensitive phenotype. The present study examined the possibility that alterations in either the ANP natriuretic pathway or endothelin (ET) system in the kidney of the salt-challenged ANP +/- mouse was responsible for its salt-sensitive phenotype. Plasma ANP levels and renal cGMP activity were increased in response to a salt load in both ANP +/+ and +/- mice. However, the mRNA expression of proANP was found to be increased only in the ANP +/- kidney along with its guanylyl cyclase-linked receptor, NPRA; the upregulation of NPRA mRNA was limited to the renal medulla. This suggests that the renal ANP pathway remains capable of responding to a salt load in the ANP +/- animal, but may be compensating for other dysfunctional pathways. We also report a significant increase in renal ET-1 mRNA and ETA receptor protein expression in medulla and cortex of the salt-treated, ANP +/- mouse, but not its wild-type counterpart. In fact, ETA expression decreased in the renal cortex of the ANP +/+ salt-treated animal. The ETB receptor expression was not affected by diet in either genotype. We hypothesize that the salt-sensitive hypertension in the ANP +/- mouse is exacerbated, and possibly driven by the vasoconstrictive effects resulting from an upregulated ET-1/ETA pathway.

The effect of asbestosis on lung cancer risk beyond the dose related effect of asbestos alone

AIMS

To determine if the presence of asbestosis is a prerequisite for lung cancer in subjects with known exposure to blue asbestos (crocidolite).

METHODS

Former workers and residents of Wittenoom with known amounts of asbestos exposure (duration, intensity, and time since first exposure), current chest x ray and smoking information, participating in a cancer prevention programme (n = 1988) were studied. The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was examined for radiographic evidence of asbestosis according to the UICC (ILO) classification. Cox proportional hazards modelling was used to relate asbestosis, asbestos exposure, and lung cancer.

RESULTS

Between 1990 and 2002 there were 58 cases of lung cancer. Thirty six per cent of cases had radiographic evidence of asbestosis compared to 12% of study participants. Smoking status was the strongest predictor of lung cancer, with current smokers (OR = 26.5, 95% CI 3.5 to 198) having the greatest risk. Radiographic asbestosis (OR = 1.94, 95% CI 1.09 to 3.46) and asbestos exposure (OR = 1.21 per f/ml-year, 95% CI 1.02 to 1.42) were significantly associated with an increased risk of lung cancer. There was an increased risk of lung cancer with increasing exposure in those without asbestosis.

CONCLUSION

In this cohort of former workers and residents of Wittenoom, asbestosis is not a mandatory precursor for asbestos related lung cancer. These findings support the hypothesis that it is the asbestos fibres per se that cause lung cancer, which can develop with or without the presence of asbestosis.

The additional risk of malignant mesothelioma in former workers and residents of Wittenoom with benign pleural disease or asbestosis

AIMS

To examine the hypothesis that people with benign pleural disease or asbestosis have an increased risk of malignant mesothelioma beyond that attributable to their degree of asbestos exposure.

METHODS

Former workers and residents of the crocidolite mining and milling town of Wittenoom are participating in a cancer prevention programme (n = 1988). The first plain chest radiograph taken at the time of recruitment into the cancer prevention programme was read for evidence of benign pleural disease and asbestosis, using the UICC classification. Crocidolite exposure of former workers was derived from employment records and records of dust measurements performed during the operation of the asbestos mine and mill between 1943 and 1966. Based on fibre counts, exposure for former residents was determined using duration of residence and period of residence (before and after a new mill was commissioned in 1957) and interpolation from periodic hygienic measures undertaken from personal monitors between 1966 and 1992. Cox proportional hazards modelling was used to relate benign pleural disease, asbestosis, asbestos exposure, and mesothelioma.

RESULTS

Between 1990 and 2002, there were 76 cases of mesothelioma (56 of the pleura and 20 of the peritoneum). Cases had more radiographic evidence of (all) benign pleural disease, pleural thickening, blunt/obliterated costophrenic angle, and asbestosis than non-cases. Adjusting for time since first exposure (log years), cumulative exposure (log f/ml-years), and age at the start of the programme, pleural thickening (OR = 3.1, 95% CI 1.2 to 7.6) and asbestosis (OR = 3.3, 95% CI 1.3 to 8.6) were associated with an increased risk of peritoneal mesothelioma. There was no increased risk for pleural mesothelioma.

CONCLUSION

The presence of benign pleural disease, in particular pleural thickening, and asbestosis appears to increase the risk of mesothelioma of the peritoneum, but not of the pleura beyond that attributable to indices of asbestos exposure in this cohort of subjects exposed to crocidolite.

Radiographic (ILO) readings predict arterial oxygen desaturation during exercise in subjects with asbestosis

BACKGROUND

Exercise impairment is common in subjects with asbestosis. Arterial oxygen desaturation during exercise is an important contributor to exercise limitation. The International Labour Office (ILO) classification of plain chest radiographs correlates with resting pulmonary function, but its value in predicting abnormal ventilatory responses to exercise, including desaturation, has not been explored.

AIMS

To determine in subjects with asbestosis (1) if radiographic profusion scores and the extent of small irregular shadows on plain chest radiographs correlate with resting lung function and abnormal ventilatory responses to exercise; and (2) if radiographic scores add value to resting lung function tests in predicting abnormal ventilatory responses to exercise.

METHODS

Thirty eight male subjects with asbestosis were included. Plain chest radiographs were read according to the ILO classification independently by three observers. All subjects underwent assessment of lung function and an incremental exercise test.

RESULTS

Profusion scores and number of affected zones correlated significantly with the percentage predicted values of single breath diffusing capacity (DLCO), forced vital capacity (FVC), and total lung capacity (TLC). Arterial oxygen desaturation occurred in 29% of the subjects. The severity of desaturation correlated significantly with profusion and the number of affected zones. The combined use of number of affected zones, FEV(1)/FVC ratio and DLCO predicted desaturation during exercise with an explained variance of 41%. VO(2)max was significantly related only to DLCO but was not predicted by the ILO score.

CONCLUSION

Arterial oxygen desaturation correlated with the profusion and extent of parenchymal abnormality on chest radiographs. The addition of morphological indices to physiological measurements is valuable for predicting oxygen desaturation during exercise but not for VO(2)max. Refinement of the radiographic scoring system and the addition of more sophisticated imaging techniques may further improve the predictive power.

Silicosis compensation in Western Australian gold miners since the introduction of an occupational exposure standard for crystalline silica

Occupational exposure limits for crystalline silica are under review worldwide because of the large numbers of exposed people and, especially, because of the recent International Agency for Research on Cancer classification of silica as a human carcinogen.

OBJECTIVES

The aims of this study were to (i) re-examine the incidence of silicosis in Western Australian gold miners and, using estimates of the total population at risk, (ii) estimate the upper confidence limit for the risk of silicosis in Western Australian gold miners since 1974, when the current exposure standard for crystalline silica was implemented.

METHODS

Work histories of cases compensated for pneumoconiosis after 1974 were examined. Numbers of workers in the total workforce likely to be exposed to crystalline silica in Western Australia were estimated as the population at risk.

RESULTS

There were no cases of compensated silicosis in Western Australian miners whose first dust exposure began during or after 1974. The upper 95% confidence interval for this zero rate was estimated to be 4.8 per 100,000 person-yr.

CONCLUSIONS

There have been no compensated cases of silicosis in Western Australia among miners first exposed to crystalline silica after introduction of the current exposure standard. A rate of compensated silicosis higher than five cases per 100,000 person-yr is unlikely.

Investigation of a cyclopic, human, term fetus by use of magnetic resonance imaging (MRI)

Using magnetic resonance imaging (MRI), the internal neural and craniofacial malformations of a cyclopic fetus are described. External facial features were characterized by a tubular proboscis situated above a single eye slit. The brain was recognized as 'pancake' type alobar holoprosencephaly (a condition where the undifferentiated telencephalon partially surrounds a monoventricle). Displacement of some bones that normally contribute to the orbit could be clearly discerned. Absence of neural structures (e.g. falx cerebri, corpus callosum) and missing components of the ethmoid bone indicated a midline deficit. This correlates with proposed theories of cyclopic embryopathy, which suggest that the prechordal plate and the neural crest cells are affected during the third week of gestation in cyclopia.

Expression of B-type natriuretic peptide in atrial natriuretic peptide gene disrupted mice

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are two hormones produced and secreted by the heart to control blood pressure, body fluid homeostasis and electrolyte balance. Each peptide binds to a common family of 3 receptors (GC-A, GC-B and C-receptor) with varying degrees of affinity. The proANP gene disrupted mouse model provides an excellent opportunity to examine the regulation and expression of BNP in the absence ofANP. A new radioimmunoassay (RIA) was developed in order to measure mouse BNP peptide levels in the plasma, atrium and ventricle of the mouse. A detection limit of 3-6 pg/tube was achieved by this assay. Results show that plasma and ventricular level of BNP were unchanged among the three genotypes of mice. However, a significant decrease in the BNP level was noted in the atrium. The homozygous mutant (ANP-/-) had undetectable levels of BNP in the atrium, while the heterozygous (ANP+/-) and wild-type (ANP+/+) mice had 430 and 910 pg/mg in the atrium, respectively. Northern Blot analysis shows the ANP-/- mice has a 40% reduction of BNP mRNA level in the atrium and a 5-fold increase in the ventricle as compared with that of the ANP+/+ mouse. Our data suggest that there is a compensatory response of BNP expression to proANP gene disruption. Despite the changes in the atrial and ventricular tissue mRNA and peptide levels, the plasma BNP level remains unaltered in the ANP-/- mice. We conclude that the inability of BNP to completely compensate for the lack of ANP eventually leads to chronic hypertension in the proANP gene disrupted mice.

Cardiac troponin I is modified in the myocardium of bypass patients

BACKGROUND

Selective proteolysis of cardiac troponin I (cTnI) is a proposed mechanism of contractile dysfunction in stunned myocardium, and the presence of cTnI degradation products in serum may reflect the functional state of the remaining viable myocardium. However, recent swine and canine studies have not demonstrated stunning-dependent cTnI degradation.

METHODS AND RESULTS

To address the universality of cTnI modification, myocardial biopsy samples were obtained from coronary artery bypass patients (n=37) before and 10 minutes after removal of cross-clamp. Analysis of biopsy samples for cTnI by Western blotting revealed a spectrum of modified cTnI products in myocardium both before and after cross-clamp, including degradation products (7 products resulting from differential N- and C-terminal processing) and covalent complexes (3 products). In particular, a 22-kDa cTnI degradation product with C-terminal proteolysis was identified, which may represent an initial ischemia-dependent cTnI modification, similar to cTnI(1-193) observed in stunned rat myocardium. Although no systematic change in amount of modified cTnI was observed, subgroups of patients displayed an increase (n=10, 85+/-5% of cTnI remaining intact before cross-clamp versus 75+/-5% after) or a decrease (n=12, 67+/-5% before versus 78+/-5% after). Electron microscopy demonstrated normal ultrastructure in biopsy samples, which suggests no necrosis was present. In addition, cTnI modification products were observed in serum through a modified SDS-PAGE methodology.

CONCLUSIONS

cTnI modification, in particular proteolysis, occurs in myocardium of bypass patients and may play a key role in stunning in some bypass patients.

Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs

BACKGROUND

Diffuse pleural thickening and pleural plaques are the commonest radiological manifestations of asbestos exposure. Differentiation between subpleural fat and non-calcified pleural plaques is important clinically and medico-legally. This study aims to determine if apparent circumscribed pleural thickening on chest radiographs is related with obesity.

METHODS

Surveillance chest x-rays of 693 former asbestos workers were read with the ILO classification. Subjects with costophrenic angle obliteration (n = 57) were analyzed separately. The remaining subjects were subdivided according to their body mass index (BMI): Group 1 < 26 kg/m(2); Group 2 26-30 kg/m(2); Group 3 > 30 kg/m(2).

RESULTS

Baseline characteristics, asbestos exposure, and profusion scores were evenly distributed. BMI of > 30 kg/m(2) was associated with a higher prevalence of pleural thickening on CXR (Gp1 = 8.5%; Gp2 = 9.3%; Gp3 = 18.3%). This relationship was strongest in the subgroups with 25-50% of the lateral chest wall involved and pleural thickness of < 10 mm.

CONCLUSIONS

Obesity (BMI > 30 kg/m(2)) is related to apparent circumscribed pleural thickening on CXR, especially thin (< 1 cm) shadows covering 25-50% of the lateral chest wall.

Chest pain in asbestos-exposed individuals with benign pleural and parenchymal disease

Many asbestos-exposed individuals complain of chest pain for which there is no clear explanation. To determine whether chest pain is associated with the presence of benign pleural or parenchymal disease on chest radiograph, we studied 1,280 subjects undergoing surveillance because of prior asbestos exposure at Wittenoom, Western Australia. All subjects completed the Rose questionnaire on chest pain and this revealed 556 subjects (43%) who experienced some chest pain. A posterior-anterior chest radiograph was performed at the same clinic visit and was subsequently graded independently by two experienced readers for diffuse parenchymal disease and pleural disease. Logistic regression models adjusted for sex, age, and cumulative asbestos exposure indicated that the presence of chest pain was significantly associated with the presence of both benign pleural disease and diffuse parenchymal disease. Further analysis after stratification of chest pain into nonanginal and anginal pain showed that there was a significant association between anginal pain and the presence of pleural and parenchymal asbestos-induced radiologic abnormalities and an association of nonanginal pain with parenchymal disease. We conclude that radiographic evidence of either parenchymal or pleural disease in subjects exposed to asbestos is significantly related to the presence of chest pain, particularly anginal pain.