Extensive Revascularization or Primary Amputation: Which Patients with Critical Limb Ischemia Should Not Be Revascularized?

[Amputation as an anticipated consequence of peripheral artery disease and ways to improve the prognosis of limb salvage]

Peripheral artery disease is a common and acute social burden worldwide. The main method of treatment of PAD consists in open surgical or endovascular revascularization. However, despite steady growth of the number and quality of interventions, the incidence of lower-limb amputation still remains at a high level. Lower-limb amputation is a severe psychological blow for the patient and leads to significant deterioration of his or her quality of life, as well as has an extremely negative prognosis concerning the frequency of subsequent complications and survival. Consequences of amputations include not only severe disability but also an unfavourable prognosis of life, thus determining the necessity of adequate prevention of such events. Reconstructive and endovascular operations, as well as amputations are associated with a significant increase of the probability of the development of major adverse cardiovascular events, the frequency of repeat hospitalizations and, finally, the cost of treatment. Prescribing pathogenetically substantiated antithrombotic therapy is considered to be one of the methods to improve the results of surgical treatment and prognosis for the patient. Presented in the article is a literature review making it possible to assess the risks and consequences of amputations in patients with PAD, as well as to determine therapy capable of improving the prognosis.

Reducing Nontraumatic Lower-Extremity Amputations by 20% by 2030: Time to Get to Our Feet: A Policy Statement From the American Heart Association

Nontraumatic lower-extremity amputation is a devastating complication of peripheral artery disease (PAD) with a high mortality and medical expenditure. There are ≈150 000 nontraumatic leg amputations every year in the United States, and most cases occur in patients with diabetes. Among patients with diabetes, after an ≈40% decline between 2000 and 2009, the amputation rate increased by 50% from 2009 to 2015. A number of evidence-based diagnostic and therapeutic approaches for PAD can reduce amputation risk. However, their implementation and adherence are suboptimal. Some racial/ethnic groups have an elevated risk of PAD but less access to high-quality vascular care, leading to increased rates of amputation. To stop, and indeed reverse, the increasing trends of amputation, actionable policies that will reduce the incidence of critical limb ischemia and enhance delivery of optimal care are needed. This statement describes the impact of amputation on patients and society, summarizes medical approaches to identify PAD and prevent its progression, and proposes policy solutions to prevent limb amputation. Among the actions recommended are improving public awareness of PAD and greater use of effective PAD management strategies (eg, smoking cessation, use of statins, and foot monitoring/care in patients with diabetes). To facilitate the implementation of these recommendations, we propose several regulatory/legislative and organizational/institutional policies such as adoption of quality measures for PAD care; affordable prevention, diagnosis, and management; regulation of tobacco products; clinical decision support for PAD care; professional education; and dedicated funding opportunities to support PAD research. If these recommendations and proposed policies are implemented, we should be able to achieve the goal of reducing the rate of nontraumatic lower-extremity amputations by 20% by 2030.

Predicting in vivo therapeutic efficacy of bioorthogonally labeled endothelial progenitor cells in hind limb ischemia models via non-invasive fluorescence molecular tomography

Human embryonic stem cells-derived endothelial progenitor cells (hEPCs) were utilized as cell therapeutics for the treatment of ischemic diseases. However, in vivo tracking of hEPCs for predicting their therapeutic efficacy is very difficult. Herein, we developed bioorthogonal labeling strategy of hEPCs that could non-invasively track them after transplantation in hind limb ischemia models. First, hEPCs were treated with tetraacylated N-azidomannosamine (Ac₄ManNAz) for generating unnatural azide groups on the hEPCs surface. Second, near-infrared fluorescence (NIRF) dye, Cy5, conjugated dibenzocylooctyne (DBCO-Cy5) was chemically conjugated to the azide groups on the hEPC surface via copper-free click chemistry, resulting Cy5-hEPCs. The bioorthogonally labeled Cy5-hEPCs showed strong NIRF signal without cytotoxicity and functional perturbation in tubular formation, oxygen consumption and paracrine effect of hEPCs in vitro. In hind limb ischemia models, the distribution and migration of transplanted Cy5-hEPCs were successfully monitored via fluorescence molecular tomography (FMT) for 28 days. Notably, blood reperfusion and therapeutic neovascularization effects were significantly correlated with the initial transplantation forms of Cy5-hEPCs such as 'condensed round shape' and 'spread shape' in the ischemic lesion. The condensed transplanted Cy5-hEPCs substantially increased the therapeutic efficacy of hind limb ischemia, compared to that of spread Cy5-hEPCs. Therefore, our new stem cell labeling strategy can be used to predict therapeutic efficacy in hind limb ischemia and it can be applied a potential application in developing cell therapeutics for regenerative medicine.

The comparative efficacy of angiosome-directed and indirect revascularisation strategies to aid healing of chronic foot wounds in patients with co-morbid diabetes mellitus and critical limb ischaemia: a literature review

BACKGROUND

Ischaemic ulcerations have been reported to persist and/or deteriorate despite technically successful revascularisations; a higher incidence of which affects patients with diabetes and critical limb ischaemia. In the context of wound healing, it is unclear if applications of the angiosome concept in 'direct revascularisation' (DR) would be able to aid the healing of chronic foot ulcerations better than the current 'best vessel' or 'indirect revascularisation' (IR) strategy in patients with co-morbid diabetes and critical limb ischaemia.

METHODS

A literature search was conducted in eight electronic databases, namely AMED, CINAHL, The Cochrane Library, ProQuest Health & Medicine Complete, ProQuest Nursing & Allied Health Source, PubMed, ScienceDirect and TRIP database. Articles were initially screened against a pre-established inclusion and exclusion criteria to determine eligibility and subsequently appraised using the Newcastle-Ottawa Scale.

RESULTS

Five retrospective studies of varying methodological quality were eligible for inclusion in this review. Critical analysis of an aggregated population (n = 280) from methodologically stronger studies indicates better wound healing outcomes in subjects who had undergone DR as compared to IR (p < 0.001; p = 0.04). DR also appears to result in a nearly twofold increase in probability of wound healing within 12 months (hazard ratio, 1.97; 95% CI, 1.34-2.90). This suggests that achieving direct arterial perfusion to the site of ulceration may be important for the healing of chronic diabetic foot ulcerations.

CONCLUSION

Incorporating an angiosome-directed approach in the lower limb revascularisation strategy could be a very useful adjunct to a solely indirect approach, which could increase the likelihood of wound healing. With the limited data currently available, findings appear promising and merit from further investigation. Additional research to form a solid evidence base for this revised strategy in patients with co-morbid diabetes and critical limb ischaemia is warranted.

Vascular Regeneration in Ischemic Hindlimb by Adeno-Associated Virus Expressing Conditionally Silenced Vascular Endothelial Growth Factor

BACKGROUND

Critical limb ischemia (CLI) is the extreme manifestation of peripheral artery disease, a major unmet clinical need for which lower limb amputation is the only option for many patients. After 2 decades in development, therapeutic angiogenesis has been tested clinically via intramuscular delivery of proangiogenic proteins, genes, and stem cells. Efficacy has been modest to absent, and the largest phase 3 trial of gene therapy for CLI reported a worsening trend of plasmid fibroblast growth factor. In all clinical trials to date, gene therapy has used unregulated vectors with limited duration of expression. Only unregulated extended expression vectors such as adeno-associated virus (AAV) and lentivirus have been tested in preclinical models.

METHODS AND RESULTS

We present preclinical results of ischemia (hypoxia)-regulated conditionally silenced (CS) AAV-human vascular endothelial growth factor (hVEGF) gene delivery that shows efficacy and safety in a setting where other strategies fail. In a BALB/c mouse model of CLI, we show that gene therapy with AAV-CS-hVEGF, but not unregulated AAV or plasmid, vectors conferred limb salvage, protection from necrosis, and vascular regeneration when delivered via intramuscular or intra-arterial routes. All vector treatments conferred increased capillary density, but organized longitudinal arteries were selectively generated by AAV-CS-hVEGF. AAV-CS-hVEGF therapy reversibly activated angiogenic and vasculogenic genes, including Notch, SDF1, Angiopoietin, and Ephrin-B2. Reoxygenation extinguished VEGF expression and inactivated the program with no apparent adverse side effects.

CONCLUSIONS

Restriction of angiogenic growth factor expression to regions of ischemia supports the safe and stable reperfusion of hindlimbs in a clinically relevant murine model of CLI.

Domains that Determine Quality of Life in Vascular Amputees

BACKGROUND

Although patients with critical limb ischemia (CLI) commonly undergo major limb amputation, the quality of life (QOL) of this group remains poorly described. Therefore, we sought to describe which domains vascular amputees consider important in determining their health-related QOL.

METHODS

We performed 4 focus groups in patients who had major lower extremity amputations resulting from CLI. They were conducted at 4 distinct centers across the United States to ensure broad geographic, socioeconomic, and ethnic representation.

RESULTS

Of 26 patients (mean age, 64 years), 19 (73%) were Caucasian, 6 (23%) were African American, and 1 (4%) was Native American. Nearly, three-quarter of patients were men (n = 19, 73%) and had a high-school education or more (n = 19, 73%). Overall, 8 (31%) were double amputees and 17 (65%) had diabetes. Time since amputation varied across patients and ranged from 3 months to more than 27 years (mean, 4.3 years). Patients stated that their current QOL was determined by impaired mobility (65%), pain (60%), progression of disease in the remaining limb (55%), and depression/frustration (54%). Across 26 patients, more than half (n = 16, 62%) described multiple prior revascularization procedures. Although most felt that their physician did his/her best to salvage the affected leg (85%), a sizable minority would have preferred an amputation earlier in their CLI treatment course (27%). Furthermore, when asked how their care might have been improved, patients reported that facilitating peer support (88%), more extensive rehabilitation and prosthetist involvement (71%), earlier mention of amputation as a possible outcome (54%), and the early discontinuation of narcotics (54%) were potential areas of improvement.

CONCLUSIONS

Although QOL in vascular amputees seems primarily determined by mobility impairment, pain, and emotional perturbation, our focus groups identified that physician-controlled factors such as the timing of amputation, informed decision making, and postamputation support may also play an important role. The assessment of patient preferences regarding maintenance of mobility at the cost of increased pain versus relief of pain with amputation at a cost of diminished mobility is central to shared decision making in CLI treatment.

Evaluation of the patient who presents with critical limb ischemia: diagnosis, prognosis, and medical management

Patients with critical limb ischemia usually have severe atherosclerotic disease and are at a high risk of limb loss as well as major adverse cardiovascular events. The current article provides a description of the clinical presentation of patients with critical limb ischemia and also discusses the initial evaluation of these patients, including physical examination, use of noninvasive vascular tests, and other imaging modalities. An overview of the general management of these patients is also provided, including the identification of patients who benefit from revascularization or primary amputation, principles of wound care, and therapies for cardiovascular risk reduction.

Preoperative Non-ambulatory Status Predicts Poor Outcome after Below Knee Bypass Surgery

OBJECTIVE

To identify the outcome of below knee bypass that focuses on the functional status and to investigate whether preoperative functional status can predict these outcomes.

MATERIALS AND METHODS

One hundred and fifty one limbs in one hundred and thirty two patients that underwent below knee bypass between 2004 and 2008 were retrospectively reviewed. The patients were grouped as "ambulatory," "non-ambulatory transfer" and "non-ambulatory bedridden," according to their functional status. Clinical success was defined as the achievement of all of following end points; graft patency to wound healing, limb salvage for 1 year or until death, maintenance of ambulatory status for 1 year, and survival for 6 months. The effect of preoperative ambulatory status was analyzed.

RESULTS

The overall primary and secondary graft patency, limb salvage and survival at 1 year were 76.3%, 81.8%, 89.1% and 84.1%, respectively. The overall success rate was 62.0%. Clinical success rates for the ambulatory and non-ambulatory groups were 75.6% and 34.9% (P = 0.0009, OR: 4.4; 95% CI: 1.8-10.6).

CONCLUSIONS

Bypass surgery is justified for maintaining the independent status of ambulatory patients. On the other hand, the high likelihood of poor outcomes for non-ambulatory patients must be considered before performing bypass surgery.

Combination Stem Cell Therapy for the Treatment of Severe Limb Ischemia: Safety and Efficacy Analysis

The infusion of a source of endothelial progenitors (EPCs) to limb ischemia (LB) patients has been used to increase angiogenesis. Because the formation of new blood vessels involves, in addition to EPCs, other cells and angiogenic regulators, we postulate that a combination cell therapy including EPCs and mesenchymal stem cells (a source of pericytes progenitors and angiogenic regulators) may represent a preferential stimuli for the development of blood vessels. In this phase I clinical trial, patients with LI were infused with a cell product consisting of autologous bone marrow-derived mononuclear and mesenchymal stem cells. After 10 2 months of follow-up, efficacy assessment demonstrated improvements in walking time, ankle brachial pressure, and quality of life. Concomitantly, angiographic and 99mTc-TF perfusion scintigraphy scores confirmed increased perfusion in the treated limbs. These results show that the use of a combination cell therapy is safe, feasible, and appears effective in patients with LI.