Data, guidelines, and practice of revascularization for claudication

Lower Extremity Bypass for Occlusive Disease: A Brief History

BACKGROUND

This is a narrative review that aims to highlight key advancements that led to the current state of lower extremity bypass surgery. It focuses on key contributors during the last century who have driven the standardization of surgical treatment of peripheral arterial occlusive disease.

METHODS

A narrative review was conducted utilizing available resources in the scientific and historical literature to track landmark achievements in the development of modern lower extremity bypass surgery for occlusive disease, focusing primarily on the last century of advancement.

RESULTS

Several critical conceptual, technological, and technical landmarks were identified as critical components of modern lower extremity bypass surgery. This includes fundamental developments in the techniques of vascular anastomosis led by Carrel and others, a developing understanding of vascular occlusive disease as a localized and segmental process with broad implementation of the techniques of arteriography, and the development of safe thromboendarterectomy aided by the development and utilization of heparin for anticoagulation. These factors led to the first femoral-to-popliteal artery bypass by Jean Kunlin in 1948. From here, advances in vascular prosthetic material pioneered by Voorhees and others, alternative vascular conduits, increasing acceptance of tibial revascularization, and dispelling the myth of diabetic "small vessel" disease broadened revascularization options for patients with complex patterns of occlusive disease and those who have limited conduit availability.

CONCLUSIONS

Modern lower extremity bypass surgery for occlusive disease arose steadily over a course of a century, driven by complex problem-solving in the pathophysiological understanding of atherosclerosis, technical developments in vascular anastomosis and arteriography, and evolution of conduit materials and pharmacologic therapy. Future advancements in bypass surgery are targeted at solving the complex problems of anastomotic intimal hyperplasia, expanding technology for alternative vascular conduits, ongoing optimization of risk factors, and scrutinizing of outcomes to make patient-centered, evidence-based decisions regarding revascularization strategy.

Skeletal muscle regeneration failure in ischemic-damaged limbs is associated with pro-inflammatory macrophages and premature differentiation of satellite cells

BACKGROUND

Chronic limb-threatening ischemia (CLTI), a severe manifestation of peripheral arterial disease (PAD), is associated with a 1-year limb amputation rate of approximately 15-20% and substantial mortality. A key feature of CLTI is the compromised regenerative ability of skeletal muscle; however, the mechanisms responsible for this impairment are not yet fully understood. In this study, we aim to delineate pathological changes at both the cellular and transcriptomic levels, as well as in cell-cell signaling pathways, associated with compromised muscle regeneration in limb ischemia in both human tissue samples and murine models of CLTI.

METHODS

We performed single-cell transcriptome analysis of ischemic and non-ischemic muscle from the same CLTI patients and from a murine model of CLTI. In both datasets, we analyzed gene expression changes in macrophage and muscle satellite cell (MuSC) populations as well as differential cell-cell signaling interactions and differentiation trajectories.

RESULTS

Single-cell transcriptomic profiling and immunofluorescence analysis of CLTI patient skeletal muscle demonstrated that ischemic-damaged tissue displays a pro-inflammatory macrophage signature. Comparable results were observed in a murine CLTI model. Moreover, integrated analyses of both human and murine datasets revealed premature differentiation of MuSCs to be a key feature of failed muscle regeneration in the ischemic limb. Furthermore, in silico inferences of intercellular communication and in vitro assays highlight the importance of macrophage-MuSC signaling in ischemia induced muscle injuries.

CONCLUSIONS

Collectively, our research provides the first single-cell transcriptome atlases of skeletal muscle from CLTI patients and a murine CLTI model, emphasizing the crucial role of macrophages and inflammation in regulating muscle regeneration in CLTI through interactions with MuSCs.

Pro-inflammatory macrophages impair skeletal muscle regeneration in ischemic-damaged limbs by inducing precocious differentiation of satellite cells

Chronic limb-threatening ischemia (CLTI), representing the end-stage of peripheral arterial disease (PAD), is associated with a one-year limb amputation rate of ∼15-20% and significant mortality. A key characteristic of CLTI is the failure of the innate regenerative capacity of skeletal muscle, though the underlying mechanisms remain unclear. Here, single-cell transcriptome analysis of ischemic and non-ischemic muscle from the same CLTI patients demonstrated that ischemic-damaged tissue is enriched with pro-inflammatory macrophages. Comparable results were also observed in a murine CLTI model. Importantly, integrated analyses of both human and murine data revealed premature differentiation of muscle satellite cells (MuSCs) in damaged tissue and indications of defects in intercellular signaling communication between MuSCs and their inflammatory niche. Collectively, our research provides the first single-cell transcriptome atlases of skeletal muscle from CLTI patients and murine models, emphasizing the crucial role of macrophages and inflammation in regulating muscle regeneration in CLTI through interactions with MuSCs.

A Policy Approach to Reducing Low-Value Device-Based Procedure Use

Policy Points Low-value care is common in clinical practice, leading to patient harm and wasted spending. Much of this low-value care stems from the use of medical device-based procedures. We describe here a novel academic-policymaker collaboration in which evidence-based clinical coverage for device-based procedures is implemented through prior authorization-based policies for Louisiana's Medicaid beneficiary population. This process involves eight steps: 1) identifying low-value medical device-based procedures based on clinical evidence review, 2) quantifying utilization and reimbursement, 3) reviewing clinical coverage policies to identify opportunities to align coverage with evidence, 4) using a low-value device selection index, 5) developing an evidence synthesis and policy proposal, 6) stakeholder engagement and input, 7) policy implementation, and 8) policy evaluation. This strategy holds significant potential to reduce low-value device-based care.

Lower Extremity Peripheral Artery Disease Without Chronic Limb-Threatening Ischemia: A Review

IMPORTANCE

Lower extremity peripheral artery disease (PAD) affects approximately 8.5 million people in the US and approximately 230 million worldwide.

OBSERVATIONS

Peripheral artery disease is uncommon before aged 50 years but affects up to 20% of people aged 80 years and older. It can be noninvasively diagnosed with the ankle-brachial index (ABI), a ratio of Doppler-recorded pressures in the dorsalis pedis and/or posterior tibial artery in each leg to brachial artery pressures. An ABI value less than 0.90 is 57% to 79% sensitive and 83% to 99% specific for arterial stenosis of at least 50%. Intermittent claudication, consisting of exertional calf pain that does not begin at rest and that resolves within 10 minutes of rest, is considered the classic symptom of PAD. However, 70% to 90% of people with an ABI value less than 0.90 either report no exertional leg symptoms (ie, asymptomatic) or report leg symptoms with walking that are not consistent with classic claudication. Over time, people with PAD restrict walking activity or slow walking speed to avoid leg symptoms. Thus, although approximately 75% of people with PAD report no change in leg symptoms over time, those with PAD have significantly greater annual declines in 6-minute walk performance compared with those without it. Approximately 11% of people with PAD develop chronic limb-threatening ischemia, the most severe form of PAD. Compared with people without PAD, those with the disease have approximately twice the rate of all-cause mortality, cardiovascular mortality, and major coronary events at 10-year follow-up. High-dose statins and antiplatelet therapy with or without antithrombotic therapy reduced rates of coronary events and stroke in people with PAD. Supervised treadmill exercise improved 6-minute walk distance by 30 to 35 m, consistent with a clinically meaningful change, whereas effective home-based walking exercise interventions improved 6-minute walk by 42 to 53 m. Effective home-based exercise programs require behavioral methods, including monitoring by a coach.

CONCLUSIONS AND RELEVANCE

Peripheral artery disease affects approximately 230 million people worldwide and is associated with increased rates of cardiovascular events, lower extremity events, and functional decline compared with that of people without PAD. People with PAD should be treated with the highest dose of statin tolerated, antithrombotic and/or antiplatelet therapy, and exercise.

External Iliac Artery to Tibial Arteries Vein Graft for Inaccessible Femoral Artery

BACKGROUND

An endovascular-first approach to limb salvage and relief from lifestyle-limiting claudication is widely accepted. Stenosis or short occlusion of common, superficial femoral, and popliteal arteries can be corrected with percutaneous transluminal angioplasty (PTA) with stent positioning. Patency rates of these procedures are limited. We report our experience with external iliac artery to the infrapopliteal vessels vein grafts when the endovascular treatment fails.

METHODS

Between January 2013 and January 2019, 16 patients (16 limbs) were operated on for limb-threatening ischemia after the occlusion of PTA with stent positioning of the common, superficial femoral, and popliteal arteries. Three patients were treated at our hospital by interventional radiologists; the remaining were operated on elsewhere. An external iliac artery to the infrapopliteal vessels vein bypass graft was anatomically interposed to restore blood flow. End points of the study were death-related events, vein graft failure, and major (above- or below-knee amputation) or minor (foot or toe amputation) limb loss.

RESULTS

There were 12 men and 4 women. Mean age of patients was 68 years. Indication for the initial PTA with stent positioning of the common and superficial femoral artery was according to the Rutherford classification Grade I: Category 1, 11 patients (69%) and Category 2, 5 (31%) patients (Stage IIa and IIb according to Fontaine classification, respectively). Great saphenous vein was used in 14 (87%) cases and in 2 (13%) cases a composite graft with a segment of cephalic vein was required. The distal anastomoses were performed on the posterior tibial artery in 6 (37%) cases, anterior tibial artery in 4 (26%), and peroneal artery in 6 (37%). Four-year survival and primary patency rates were 71% (standard error [SE] = 0.15) and 73% (SE = 0.14), respectively. One graft occlusion required an above-knee amputation. Four-year limb salvage rate was 86% (SE = 0.13).

DISCUSSION

We recommend the external iliac artery as source of inflow in patients in whom the vein bypass cannot originate from the common femoral or from a more distal inflow source because of previous PTA with stent positioning or it is deemed hazardous.