Accuracy of quantitative vessel analysis in endovascular treatment for femoropopliteal lesions

BACKGROUND

Our aim was to evaluate the accuracy of quantitative vessel analysis (QVA) in measuring the reference vessel diameter (RVD) of femoropopliteal lesions.

METHODS

Between October 2014 and September 2015, 30 consecutive femoropopliteal lesions in 25 patients who underwent endovascular therapy (EVT) under intravascular ultrasound (IVUS) guidance were analyzed. RVDs measured using QVA_sheath (calibrated using a 6-Fr sheath in the common femoral artery) and QVA_ruler (calibrated using a ruler on the angiography table) were compared to those obtained using IVUS as the reference values.

RESULTS

The mean QVA_sheath-measured RVD was significantly larger than the mean IVUS-measured RVD (5.34±1.29 vs. 5.07±1.20 mm, P=0.001). In contrast, mean QVA_ruler-measured RVD was 4.60±1.04 mm, which was significantly smaller than both the mean IVUS- and mean QVA_sheath-measured RVD (both P<0.001). Bland-Altman analysis revealed that the 95% limits of agreement versus IVUS ranged from -0.94 to 1.49 mm for QVA_sheath and -1.69 to 0.76 mm for QVA_ruler, respectively. Agreement with tolerance of ±1.00 mm accounted for 88% of QVA_sheath and 83% of QVA_ruler (P=0.60). The difference between QVA- and IVUS-measured RVDs was inversely correlated with the distance from the table (P=0.029 for QVA_sheath and P=0.003 for QVA_ruler).

CONCLUSIONS

The accuracy of both QVA_sheath and QVA_ruler in measuring RVD were similarly suboptimal. Over- and under-estimation of RVD is not rare in QVA.

[Interventional Treatments for Femoropopliteal Arterial Disease and Recent Updates]

Peripheral arterial occlusive disease (PAOD) of the femoropopliteal artery is commonly caused by atherosclerosis. It can present with varying clinical symptoms depending on the degree of disease, ranging from intermittent claudication to critical limb ischemia and tissue loss. Therefore, appropriate and timely treatment is required to improve symptoms and salvage the affected limbs. Interventional approaches for femoropopliteal arterial disease commonly include percutaneous transluminal angioplasty, atherectomy, and stent placement. Over the years, endovascular recanalization has been widely performed for treating PAOD due to continuous developments in its techniques and availability of dedicated devices with the inherent advantage of being minimal invasive. In this review, we introduce various types of endovascular treatment methods, discuss the results of clinical research from existing literature, and illustrate the treatment procedures using representative images.

Comparative Effectiveness of Endovascular Treatment Modalities for De Novo Femoropopliteal Lesions: A Network Meta-analysis of Randomized Controlled Trials

Purpose: To report the results of a network meta-analysis of randomized controlled trials (RCTs) comparing multiple endovascular treatments for de novo femoropopliteal lesions. Materials and Methods: The MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases were systematically searched on June 1, 2019, for prospective RCTs comparing 14 treatments [ie, atherectomy, brachytherapy, cryoplasty, cutting balloons, drug-coated balloons, bare nitinol stents, drug-eluting stents (DES), covered stents (CS), and combinations] in the treatment of de novo femoropopliteal lesions. Outcomes were technical success; binary restenosis and target lesion revascularization (TLR) at 6, 12, and/or 24 months; and all-cause mortality at 12 months. Ultimately, 53 articles reporting on 45 studies (91 study arms; 5565 patients) were selected. For the technical success outcome, all types of stents, all balloons, and all atherectomy devices were aggregated in stent, balloon, and atherectomy technology groups, respectively. Results: In terms of technical success for aggregated treatment types, stent technology was the most effective treatment and was better than balloon and atherectomy technologies. In terms of binary restenosis, DES was the most effective single treatment at the 6- and 12-month follow-up and CS at the 24-month follow-up. Both DES and CS were better than the majority of other single treatments, including balloon angioplasty, cutting balloon, cryoplasty, directional atherectomy, and bare nitinol stent during all follow-up periods. In terms of TLR, DES was the second most effective single treatment and the most effective single treatment at the 6- and 12-month follow-up intervals; CS was the most effective single treatment at the 24-month follow-up. Both DES and CS were better than the majority of other single treatments. The 12-month all-cause mortality of both DES and CS were similar to other treatments, whereas cryoplasty seemed to be the least effective treatment with regard to binary restenosis and TLR. Conclusion: Both DES and CS had substantial advantages in terms of restenosis and TLR in femoropopliteal lesions and were similar to aggregate stent technology in terms of technical success. DES performed better within 12 months after operation and CS at ~24 months, but neither had much advantage in terms of mortality. In contrast, cryoplasty seemed to be a less effective treatment.

The evidence to support the use of focal force balloon technology to improve outcomes in the treatment of lower extremity arterial occlusive disease

Despite recent advances in endovascular therapy of lower extremity atherosclerotic disease, mainly driven through drug eluting balloon angioplasty, treatment of complex lesions remains challenging. Drug-eluting balloons work less well in heavily calcified lesions and in particular long lesions often require bail-out stenting. Lesion preparation, as a stand-alone treatment or before delivering antiproliferative therapy or scaffolding, has gained increased recognition in recent years. Focal force or other specialty balloons are designed to prepare complex lesions to improve acute technical success and, ideally, long term patency of the vessel. There are numerous dedicated balloons on the market that use different modes of action to prepare the lesions. The current review focuses on mechanistic insights and the evidence behind those specialty balloons.

When Are Endovascular and Open Bypass Treatments Preferred for Femoropopliteal Occlusive Disease?

Several meta-analyses and multicenter trials have shown that chronic limb ischemia did not occur for up to 5 years in 50%–70% of patients who underwent saphenous vein grafts, with limb salvage and perioperative mortality rates of >80% and 3%, respectively. However, open surgical bypass can have limitations, including postoperative morbidity/wound complications of 10%–20% and prolonged length of hospital stay and outpatient care. Several studies have analyzed clinical outcomes for patients with critical limb ischemia treated with endovascular therapies, but they have been mainly retrospective with significant heterogeneity or were single center. Only few randomized trials have compared surgical vs. endovascular therapy. These included the Bypass vs. Angioplasty in Severe Ischemia of the Leg (BASIL) trial, with no differences found in amputation-free or overall survival rates at 1 year; however, late outcomes favored the surgical group. The Bypass or Angioplasty in Severe Intermittent Claudication (BASIC) trial concluded that the 1-year patency rates were 82% and 43% for bypass and angioplasty, respectively. The BEST Endovascular vs. Best Surgical Therapy in Patients with Critical Limb Ischemia (BEST-CLI) trial is currently enrolling patients. This review analyzed studies comparing open vs. endovascular therapy in patients with femoropopliteal disease. (This is a review article based on the invited lecture of the 45th Annual Meeting of Japanese Society for Vascular Surgery.)

Effect of an NSE PTA balloon in experimental lesion models

The effect of a scoring balloon has been reported. However, it is difficult to compare the effect of conventional vs. scoring balloons on the same lesion. Therefore, we assessed the scoring effect of the NSE with and without elements. The endpoints of this study were scoring grade in the eccentric agar model and crack incidence in the eccentric plaster model after ballooning. The scoring grade consisted of 5 levels: (1) almost none, (2) only at the surface, (3) cleavage in the depth of less than two-thirds, (4) cleavage in the depth of two-thirds or more, and (5) collapse. The scoring grade was assessed by blinded reviewers. To estimate the incidence of crack after ballooning for plaster model, balloon expansion pressure was recorded when plaster was broken. In the eccentric agar model, the overall scoring grade was significantly higher in the NSE group compared with the NSE without elements group (p = 0.002). The scoring grade at a diameter of 4.0 mm was significantly higher in the NSE group (p = 0.018). The scoring grade at nominal pressure was significantly higher in the NSE group (p = 0.016). In the eccentric plaster model, the crack incidence of the calcified region was overall significantly higher in the NSE group than that in the NSE without elements group (63 vs. 42 %, p = 0.04). A crack was found at calcification severity ≥180° in the NSE group (84 vs. 56 %, p = 0.014). Our result suggested that NSE exhibited a higher scoring effect in both models compared with conventional balloons.

The influence of composition and location on the toughness of human atherosclerotic femoral plaque tissue

The toughness of femoral atherosclerotic tissue is of pivotal importance to understanding the mechanism of luminal expansion during cutting balloon angioplasty (CBA) in the peripheral vessels. Furthermore, the ability to relate this parameter to plaque composition, pathological inclusions and location within the femoral vessels would allow for the improvement of existing CBA technology and for the stratification of patient treatment based on the predicted fracture response of the plaque tissue to CBA. Such information may lead to a reduction in clinically observed complications, an improvement in trial results and an increased adoption of the CBA technique to reduce vessel trauma and further endovascular treatment uptake. This study characterises the toughness of atherosclerotic plaque extracted from the femoral arteries of ten patients using a lubricated guillotine cutting test to determine the critical energy release rate. This information is related to the location that the plaque section was removed from within the femoral vessels and the composition of the plaque tissue, determined using Fourier Transform InfraRed spectroscopy, to establish the influence of location and composition on the toughness of the plaque tissue. Scanning electron microscopy (SEM) is employed to examine the fracture surfaces of the sections to determine the contribution of tissue morphology to toughness. Toughness results exhibit large inter and intra patient and location variance with values ranging far above and below the toughness of healthy porcine arterial tissue (Range: 1330-3035 for location and 140-4560J/m(2) for patients). No significant difference in mean toughness is observed between patients or location. However, the composition parameter representing the calcified tissue content of the plaque correlates significantly with sample toughness (r=0.949, p<0.001). SEM reveals the presence of large calcified regions in the toughest sections that are absent from the least tough sections. Regression analysis highlights the potential of employing the calcified tissue content of the plaque as a preoperative tool for predicting the fracture response of a target lesion to CBA (R(2)=0.885, p<0.001).

STATEMENT OF SIGNIFICANCE

This study addresses a gap in current knowledge regarding the influence of plaque location, composition and morphology on the toughness of human femoral plaque tissue. Such information is of great importance to the continued improvement of endovascular treatments, particularly cutting balloon angioplasty (CBA), which require experimentally derived data as a framework for assessing clinical cases and advancing medical devices. This study identifies that femoral plaque tissue exhibits large inter and intra patient and location variance regarding tissue toughness. Increasing calcified plaque content is demonstrated to correlate significantly with increasing toughness. This highlights the potential for predicting target lesion toughness which may lead to an increased adoption of the CBA technique and also further the uptake of endovascular treatment.

An overview of optimal endovascular strategy in treating the femoropopliteal artery: mechanical, biological, and procedural factors

Treatment of the femoropopliteal (FP) artery remains a challenge to the endovascular specialist. Long-term patency is low with a high rate of target lesion revascularization. The true patency rate varies considerably between studies partly because there is a lack of uniform performance criteria and reporting standards in peripheral arterial interventions. Literature review supports three principles that emerge as important components of an optimal strategy in treating the FP artery: (1) improving vessel compliance and subsequently less dissections and bailout stenting, (2) reducing smooth muscle cell proliferation, and (3) protecting outflow vessels from distal embolization. In this overview, we examine current data that support the validity of this strategy.

Endovascular techniques in limb salvage: cutting, cryo, brachy, and drug-eluting balloons

The complex pathophysiology response to injury of the lower-extremity arteries has prompted the development of several unique balloon technologies to overcome initial technical failures and short-term intimal hyperplasia. Cryoplasty alters the cellular and mechanical properties of the vessel wall during angioplasty. Cutting balloons incise the wall, preventing elastic recoil and allowing expansion of the lumen at a lower pressure, thus limiting barotrauma. Drug-eluting balloons actively transfer inhibitory compounds to the wall during the initial therapy, while brachytherapy balloons allow for localized delivery of radiation to inhibit the proliferative response seen after angioplasty. These platforms provide unique means to enhance immediate and short-term results and also reduce stent usage in the lower extremity.

Systematic review and meta-analysis of additional technologies to enhance angioplasty for infrainguinal peripheral arterial occlusive disease

Background

There are several additional techniques designed to enhance conventional percutaneous transluminal balloon angioplasty (PTA). This systematic review assessed current evidence on the clinical effectiveness of additional techniques for infrainguinal peripheral arterial occlusive disease (PAD).

Methods

Relevant electronic databases, including MEDLINE, were searched in May 2011. The population comprised participants with symptomatic PAD undergoing endovascular treatment for disease distal to the inguinal ligament. Interventions were additional techniques compared with conventional PTA. Main outcome measures were restenosis and need for reintervention. Randomized clinical trials (RCTs) of clinical effectiveness were assessed for quality and data were extracted. Where appropriate, meta-analysis was undertaken to produce risk ratios (RRs).

Results

Forty RCTs were selected. Meta-analysis showed a significant benefit in reducing restenosis rates at 6 months for self-expanding stents (RR 0·49) and drug-coated balloons (RR 0·40), and at 12 months for endovascular brachytherapy (RR 0·63). There was also evidence that use of a stent-graft significantly reduced restenosis compared with PTA, as did drug-eluting stents compared with bare-metal stents. Meta-analysis showed that use of drug-coated balloons was associated with significantly lower reintervention rates than PTA alone at 6 months (RR 0·24) and 24 months (RR 0·27) of follow-up. There was also evidence of significantly lower reintervention rates for self-expanding stents at 6 months. Other techniques did not show significant treatment effects for restenosis or reintervention.

Conclusion

The conclusions of this review should be tempered by small sample sizes, lack of clinical outcome measures and differing outcome definitions, making direct comparison across trials difficult. However, self-expanding stents, drug-eluting stents and drug-coated balloons appeared to be the most promising technologies worthy of future study.