Catheter-Directed Thrombolysis for (Not Immediately) Threatened Acute Lower Limb Ischemia: Clinical Outcome and Efficacy.

OBJECTIVE: The objective of this study was to examine the short- and midterm outcomes of catheter-directed thrombolysis (CDT) for acute lower limb ischemia (ALI), classes Rutherford 1 and 2, with specific attention to functional outcome. METHODS: This retrospective study included patients with ALI treated with CDT from 2 vascular centers between May 2018 and April 2021. Cases were analyzed in groups according to the Rutherford (1 and 2) classification. The primary endpoint was functional outcome during follow-up, assessed by Rutherford's chronic limb ischemia classification. Functional outcomes over time were analyzed by generalized estimating equations. Kaplan-Meier analysis was used to estimate reintervention, amputation, survival, and reintervention-free survival rates. RESULTS: Two hundred cases were included (Rutherford 1, n = 51; Rutherford 2, n = 149). Total median treatment duration was 27 hours in the Rutherford 1 group and 39 hours in the Rutherford 2 group (P= 0.120). Initial clinical success was high (Rutherford 1, 82% vs Rutherford 2, 89%; P= 0.253). Complications were comparable between the 2 groups: major bleeding 8% vs 10% (P= 0.634), major amputation 4% vs 7% (P= 0.603), and mortality 6% vs 6% (P= 0.967). Median follow-up was 32 months (0-63 months). During follow-up, there was a high number of reinterventions (43%) and amputations (20%) in patients with Rutherford 1 limb ischemia, which was comparable to patients with Rutherford 2 limb ischemia. Fifty-six percent of the patients with Rutherford 1 limb ischemia reaching 2 years of follow-up were asymptomatic, 20% had mild and 16% had moderate to severe claudication. Initial clinical success following CDT and not immediately threatened ischemia at presentation are associated with improved functional outcomes during follow-up (P < 0.001 and P= 0.009, respectively). CONCLUSIONS: In our cohort, CDT was effective in reestablishing arterial flow for not immediately threatened ALI. Patients with Rutherford 1 limb ischemia who receive CDT had a more favorable functional outcome than patients with more severe limb ischemia (Rutherford 2). However, reinterventions were required frequently, and there was a substantial risk of complications. CLINICAL IMPACT: Acute lower limb ischemia (ALI) does not immediately jeopardize limb survival in patients with Rutherford 1 limb ischemia but can induce disabling claudication. In such patients, catheter-directed thrombolysis (CDT) is often performed to improve functional outcome. However, previous reports warned about the complications of CDT, and so far, mid- and long-term functional outcomes have not been reported. This study, in which a large cohort of patients with ALI was included, demonstrates a high technical success of CDT for not immediately threatened ALI with more favorable functional outcomes when compared with those with threatened limbs. Nevertheless, major complications pose a serious risk, and the need for reinterventions in the long term is high.

Systematic Review of Outcome Reporting for Interventions to Treat Patients with Acute Lower Limb Ischaemia.

OBJECTIVE: Inconsistencies in outcome data of therapeutic strategies for acute lower limb ischaemia (ALI) have hindered the synthesis of findings. A core outcome set (COS) may offer a solution to this problem by defining a minimum set of outcomes that are considered essential to all stakeholders involved. The first step in developing a COS is to review the previously reported outcomes on various treatment strategies for ALI. DATA SOURCES: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science databases were searched from inception to August 2023. REVIEW METHODS: This systematic review was conducted in accordance with the Core Outcome Measures in Effectiveness Trials (COMET) initiative framework, adhering to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and was pre-registered with PROSPERO (CRD42022320073). Abstracts were independently screened by two authors for full text review. All outcomes and their definitions were extracted from selected papers. Outcomes with different terminologies were then categorised into an agreed outcome term. The list of agreed outcomes was given a standardised outcome domain and core area using a 38 item standardised taxonomy. RESULTS: Of 6 184 articles identified, 176 relevant studies were included, yielding 1 325 verbatim outcomes. After deduplication, 72 unique verbatim outcomes were categorised into five broad outcome domains. Outcomes considered key to the evaluation of treatment of ALI were further categorised as delivery of care (19.4%), vascular outcomes (13.8%), and adverse events (12.5%). The three most frequently reported agreed outcomes were amputation (14.1%), death (12.3%), and general bleeding (11.6%). CONCLUSION: This systematic review provides an overview of currently reported outcomes in the literature of interventions for ALI. After categorisation into agreed outcome terms, 72 outcomes were identified that can be used in the development of a COS.

Catheter Directed Thrombolysis for Not Immediately Threatening Acute Limb Ischaemia: Systematic Review and Meta-Analysis.

OBJECTIVE: This systematic review and meta-analysis reports the outcomes of catheter directed thrombolysis (CDT) in patients with not immediately threatening (Rutherford I) acute lower limb ischaemia (ALI). DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search of PubMed, Embase, and the Cochrane Library was performed to identify observational studies and trials published between 1990 and 2022 reporting on the results of CDT in patients with Rutherford I ALI. A meta-analysis was performed using a random effects model with 95% confidence intervals (CIs). The outcomes of interests were treatment duration, angiographic success, bleeding complications, amputation and mortality rates, primary and secondary patency, and functional outcome expressed as pain free walking distance. RESULTS: Thirty-nine studies were included, comprising 1 861 patients who received CDT for not immediately threatening ALI. Funnel plots showed an indication of publication bias, and heterogeneity was substantial. Data from 5 to 13 studies were included in the meta-analysis. The pooled treatment duration was 2 days (95% CI 1 - 2), with an angiographic success rate of 80% (95% CI 73 - 86) and a 30 day freedom of amputation rate of 98% (95% CI 92 - 100). The major bleeding rate was 5% (95% CI 2 - 14), with a 30 day mortality rate of 3% (95% CI 1 - 5). The amputation free survival rate was 71% (95% CI 62 - 80) at the one year and 63% (95% CI 51 - 73) at the three year follow up. Long term patency rates were retrieved from four studies: 48% at one year (95% CI 27 - 70). No data could be retrieved on patient walking distance. CONCLUSION: Although CDT in the treatment of not immediately threatening ALI showed high angiographic success, the long term outcomes were relatively poor, with low patency and a substantial risk of major amputation. Further research is required to interpret the outcome of CDT in the context of potential confounders such as age and comorbidities.

Major Bleeding During Thrombolytic Therapy for Acute Lower Limb Ischaemia: Value of Laboratory Tests for Clinical Decision Making, 17 Years of Experience.

OBJECTIVE: Regular measurement of fibrinogen as dose guidance in catheter directed thrombolysis (CDT) for acute limb ischaemia (ALI) has recently been dropped from European guidelines based on inconsistent literature. This study aimed to determine whether low fibrinogen levels and high activated partial thromboplastin time (APTT) are associated with an increased major bleeding risk during CDT. METHODS: All consecutive patients treated with CDT for ALI in two Dutch hospitals between January 2004 and April 2021 were analysed retrospectively. Patients were treated with two dosing regimens (low dose: 50 000 IU/hour; high dose: 100 000 IU/hour) of urokinase and, after 2018, with a single low dose regimen of alteplase (rtPA) due to urokinase manufacturing problems. The incidence of major bleeding and associated APTT and fibrinogen levels were reviewed from patient charts. RESULTS: Of the 443 included cases, 277 underwent CDT with urokinase and 166 with rtPA. The incidence of major bleeding in the whole cohort was 7%. Patients with a fibrinogen levels < 1.0 g/L developed more major bleeding than those in whom the fibrinogen level did not drop below 1.0 g/L (15% vs. 6%; p = .041). Systemic heparinisation during CDT or high (> 80 seconds) APTT were not significantly associated with major bleeding. Angiographic success (47% vs. 72%; p = .003) and 30 day amputation free survival (53% vs. 82%; p < .001) were lower for cases with major bleeding. Older age (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.02 - 1.11), cardiac history (OR 3.35, 95% CI 1.39 - 8.06), high dose regimens (≥ 75 000 IU/hour urokinase; OR 2.67, 95% CI 1.18 - 6.04), and fibrinogen values < 1.0 g/L (OR 5.59, 95% CI 1.98 - 15.77) were independent predictors for major bleeding during CDT. CONCLUSION: High dose thrombolytic regimens and fibrinogen levels of ≤ 1.0 g/L are associated with more major bleeding during thrombolytic therapy. Major bleeding significantly worsened the clinical outcome. A prospective comparative study is needed to assess the benefit of monitoring fibrinogen levels.

Feasibility of Microbubble-Accelerated Low-Dose Thrombolysis of Peripheral Arterial Occlusions Using an Ultrasound Catheter.

PURPOSE: Intra-arterial administration of microbubbles (MBs) through an ultrasound (US) catheter increases the local concentration of MBs into the thrombus and may further enhance outcomes of contrast-enhanced sonothrombolysis (CEST). The objective of this study was to evaluate the feasibility and lytic efficacy of intra-arterial infusion of MBs during US-enhanced thrombolysis in both in vitro and in vivo peripheral arterial occluded models. MATERIALS AND METHODS: SonoVue and Luminity MBs were infused at a flow rate of 20 mL/h through either the drug delivery lumen of the US catheter (DDC, n=20) or through the tube lumen of the vascular phantom (systematic infusion, n=20) during thrombolysis with a low-dose urokinase (UK) protocol (50 000 IU/h) with(out) US application to assess MB survivability and size by pre-treatment and post-treatment measurements. A human thrombus was placed into a vascular phantom of the flow system to examine the lytic effects of CEST by post-treatment D-dimer concentrations measurements of 5 treatment conditions (saline, UK, UK+US, UK+US+SonoVue, and UK+US+Luminity). Thrombolytic efficacy of localized MBs and US delivery was then investigated in vivo in 5 porcine models by arterial blood flow, microcirculation, and postmortem determined thrombus weight and remaining length. RESULTS: US exposure significantly decreased SonoVue (p=0.000) and Luminity (p=0.000) survivability by 37% and 62%, respectively. In vitro CEST treatment resulted in higher median D-dimer concentrations for the SonoVue (0.94 [0.07-7.59] mg/mL, p=0.025) and Luminity (0.83 [0.09-2.53] mg/mL, p=0.048) subgroups when compared with thrombolysis alone (0.36 [0.02-1.00] mg/mL). The lytic efficacy of CEST examined in the porcine model showed an improved median arterial blood flow of 21% (7%-79%), and a median thrombus weight and length of 1.02 (0.96-1.43) g and 2.25 (1.5-4.0) cm, respectively. One allergic reaction and 2 arrhythmias were observed due to the known allergic reaction on lipids in the porcine model. CONCLUSION: SonoVue and Luminity can be combined with an US catheter and could potentially accelerate thrombolytic treatment of peripheral arterial occlusions. CLINICAL IMPACT: Catheter-directed thrombolysis showed to be an effective alternative to surgery for acute peripheral arterial occlusions, but this technique is still associated with several limb and life-threatening complications. The effects of thrombolysis on clot dissolution may be further enhanced by intra-arterial administration of microbubbles through an ultrasound catheter. This study demonstrates the feasibility and lytic efficacy of intra-arterial infusion of microbubbles during US-enhanced thrombolysis in both in vitro and in vivo peripheral arterial occluded models.

Microbubbles and Ultrasound Accelerated Thrombolysis for Peripheral Arterial Occlusions: The Outcomes of a Single Arm Phase II Trial.

OBJECTIVE: Acute peripheral arterial occlusions can be treated by catheter directed thrombolysis (CDT). However, CDT is time consuming and accompanied by the risk of bleeding complications. The addition of contrast enhanced ultrasound and microbubbles could improve thrombus susceptibility to thrombolytic agents and potentially shorten treatment time with a lowered risk of bleeding complications. This article reports the outcomes of the safety and feasibility of this novel technique. METHODS: In this single arm phase II trial, 20 patients with acute lower limb ischaemia received CDT combined with an intravenous infusion of microbubbles and locally applied ultrasound during the first hour of standard intra-arterial thrombolytic therapy. The primary endpoint was safety, i.e., occurrence of serious adverse events (haemorrhagic complications and/or amputation) and death within one year. Secondary endpoints included angiographic and clinical success, thrombolysis duration, additional interventions, conversion, and quality of life. RESULTS: The study included 20 patients (16 men; median age 68.0 years; range, 50.0 - 83.0; and 40% native artery and 60% bypass graft). In all patients, the use of microbubble contrast enhanced sonothrombolysis could be applied successfully. There were no serious adverse events related to the experimental treatment. Duplex examination showed flow distal from the occlusion after 23.1 hours (range 3.1 - 46.5) with a median thrombolysis time of 47.5 hours (range 6.0 - 81.0). The short term ABI and pain scores significantly improved; however, no changes were observed before or after thrombolysis in the microcirculation. Overall mortality and amputation rates were both 2% within one year. The one year patency rate was 55%. CONCLUSION: Treatment of patients with acute peripheral arterial occlusions with contrast enhanced sonothrombolysis is feasible and safe to perform in patients. Further research is necessary to investigate the superiority of this new treatment over standard treatment.

Image Fusion During Standard and Complex Endovascular Aortic Repair, to Fuse or Not to Fuse? A Meta-analysis and Additional Data From a Single-Center Retrospective Cohort.

PURPOSE: To determine if image fusion will reduce contrast volume, radiation dose, and fluoroscopy and procedure times in standard and complex (fenestrated/branched) endovascular aneurysm repair (EVAR). MATERIALS AND METHODS: A search of the PubMed, Embase, and Cochrane databases was performed in December 2019 to identify articles describing results of standard and complex EVAR procedures using image fusion compared with a control group. Study selection, data extraction, and assessment of the methodological quality of the included publications were performed by 2 reviewers working independently. Primary outcomes of the pooled analysis were contrast volume, fluoroscopy time, radiation dose, and procedure time. Eleven articles were identified comprising 1547 patients. Data on 140 patients satisfying the study inclusion criteria were added from the authors' center. Mean differences (MDs) are presented with the 95% confidence interval (CI). RESULTS: For standard EVAR, contrast volume and procedure time showed a significant reduction with an MD of -29 mL (95% CI -40.5 to -18.5, p<0.001) and -11 minutes (95% CI -21.0 to -1.8, p<0.01), respectively. For complex EVAR, significant reductions in favor of image fusion were found for contrast volume (MD -79 mL, 95% CI -105.7 to -52.4, p<0.001), fluoroscopy time (MD -14 minutes, 95% CI -24.2 to -3.5, p<0.001), and procedure time (MD -52 minutes, 95% CI -75.7 to -27.9, p<0.001). CONCLUSION: The results of this meta-analysis confirm that image fusion significantly reduces contrast volume, fluoroscopy time, and procedure time in complex EVAR but only contrast volume and procedure time for standard EVAR. Though a reduction was suggested, the radiation dose was not significantly affected by the use of fusion imaging in either standard or complex EVAR.

A Systematic Review of Pericolic Extraluminal Air in Left-Sided Acute Colonic Diverticulitis.

BACKGROUND: Although approximately 15% of all patients with acute colonic diverticulitis have pericolic extraluminal air found on computed tomography (CT), studies on the natural course and treatment of these patients are scarce. It is not clear whether these patients behave as mild uncomplicated diverticulitis or as severe diverticulitis needing more aggressive treatment. Consequently, there is no consensus about the treatment, guidelines do not discuss this group of patients, and physicians treat these patients based on their own experiences and opinion. An evidence-based approach is needed to prevent overtreatment or undertreatment in patients with pericolic extraluminal air. METHODS: PubMed and EMBASE databases were searched for all studies reporting clinical outcomes of the initial diverticulitis episode of CT-proven left-sided colonic diverticulitis. Primary outcome measures were the need for emergency surgery and percutaneous abscess drainage. RESULTS: A total of eight studies with 251 patients with pericolic extraluminal air were included. Rates of emergency surgery in isolated patients with pericolic extraluminal air were reported in six studies, yielding a pooled rate of 6% (95% confidence interval [CI] 3%-12%). In three studies reporting a combined total of only 56 patients, no patient underwent percutaneous abscess drainage. The long-term (6 mo) need for surgery was 38% in one study, although reasons for surgery were lacking. CONCLUSION: An initial 94% success rate of non-operative treatment in left-sided colonic diverticulitis patients with pericolic extraluminal air seems to justify a conservative approach including antibiotic agents. Low-quality evidence indicates the need for surgery in up to 38% in the medium-long term.