A prospective analysis of critical limb ischemia: factors leading to major primary amputation versus revascularization

Gender differences in diabetes-related lower extremity amputations

BACKGROUND

Diabetes is a major cause of morbidity and mortality in the United States, with much of the economic and social costs related to macrovascular and microvascular complications, such as myocardial infarctions, renal failure, and lower extremity amputations. While racial/ethnic differences in diabetes are well documented, less attention has been given to differences in diabetes outcomes by gender.

QUESTIONS/PURPOSES

Does gender influence the rate of diabetes-related lower extremity amputations and/or the rate of mortality after amputation?

METHODS

I reviewed the literature utilizing peer-reviewed publications found through MEDLINE searches. WHERE ARE WE NOW?: Major complex gender differences exist in diabetes-related lower extremity amputations: men are more likely to undergo lower extremity amputations, but women apparently have higher mortality related to these procedures. The reasons for such differences are not entirely clear, but it appears biologic factors may play important roles (increased rates of peripheral vascular disease and peripheral neuropathy in men, interaction between gender and cardiac mortality in women). WHERE DO WE NEED TO GO?: More research is warranted to confirm gender differences in diabetes-related lower extremity amputation mortality and explore underlying mechanisms for the gender differences in lower extremity amputations and its associated mortality. HOW DO WE GET THERE?: Exploring gender disparities in diabetes-related outcomes, such as lower extremity amputations, will need to become a national priority from a research (eg, National Institutes of Health) and policy (eg, Centers for Medicare and Medicaid Services) perspective. Only when we have a better understanding of the causes of such differences can we begin to make strides in addressing them.

Critical evaluation of endovascular surgery for limb salvage

Rest pain, tissue loss, and gangrene are manifestations of critical limb ischemia caused by peripheral arterial disease and define a patient subgroup at highest risk for major limb amputation. Patients with nonhealing lower extremity wounds should be screened for the risk factors for peripheral arterial disease and offered noninvasive vascular testing. The diagnosis of critical limb ischemia mandates prompt institution of medical and surgical management to achieve the best chance of limb salvage. Surgical intervention has evolved from primary amputation to open bypass to the present era of endovascular therapy. The goals of surgical bypass and endovascular therapy are to improve perfusion sufficiently to permit healing. Despite poorer patency rates and the more frequent need for reintervention, endovascular therapy has been shown in multiple retrospective studies to achieve limb salvage similar to open bypass. Only one large, prospective, randomized controlled trial exists comparing open bypass with endovascular therapy: The Bypass versus Angioplasty in Severe Limb Ischemia of the Leg (BASIL) trial. Close clinical surveillance and serial monitoring of limb perfusion by means of noninvasive arterial studies are needed to determine the need for further vascular intervention. Limb salvage patients suffer from multiple comorbidities and benefit from a multidisciplinary, team approach to care.

Noninvasive assessment of lower extremity hemodynamics in individuals with diabetes mellitus

The timely and accurate noninvasive assessment of peripheral arterial disease (PAD) is a critical component of a limb preservation initiative in patients with diabetes mellitus. Noninvasive vascular studies (NIVS) can be useful in screening patients with diabetes for PAD. In patients with clinical signs or symptoms, NIVS provide crucial information on the presence, location, and severity of PAD, as well as an objective assessment of the potential for primary healing of an index wound or a surgical incision. Appropriately-selected NIVS are important in the decision-making process to determine whether and what type of intervention might be most appropriate, given the clinical circumstances. Hemodynamic monitoring is likewise very important following either an endovascular procedure or a surgical bypass. Surveillance studies, usually with a combination of physiologic testing and imaging with duplex ultrasound, accurately identify recurrent disease prior to the occurrence of thrombosis, allowing targeted reintervention. NIVS can be broadly grouped into three general categories: physiologic or hemodynamic measurements; anatomic imaging; and measurements of tissue perfusion. These types of tests and suggestions for their appropriate application in patients with diabetes are reviewed.

Critical limb ischemia

Critical limb ischemia (CLI) continues to be a significantly morbid disease process for the aging population. Rigid guidelines for the management of patients with CLI are inappropriate due to the complexities that are involved in optimally treating these patients. A thin line exists in the decision process between medical management vs surgical management by revascularization or amputation, and the perception of "success" in this patient population is evolving. This review explores these issues and examines the challenges the treating physician will face when managing the care of patients with CLI. The epidemiology and natural history of CLI is discussed, along with the pathophysiology of the disease process. A review of the literature in regards to the different treatment modalities is presented to help the physician optimize therapy for patients with CLI. New scoring systems to help predict outcomes in patients with CLI undergoing revascularization or amputation are discussed, and an overview of the current status of patient-oriented outcomes is provided. Finally, we briefly examine emerging therapies for the treatment of CLI and provide an algorithm to help guide the practicing physician on how to approach the critically ischemic limb with regard to the complicated issues surrounding these patients.

Early detection of lesions of dorsal artery of foot in patients with type 2 diabetes mellitus by high-frequency ultrasonography

This study evaluated the value of high-frequency ultrasonograpy for early detection of dorsal artery of foot in patients with type 2 diabetes mellitus (MD). Eighty subjects including 40 patients with type 2 MD (T2DM group) and 40 healthy volunteers (NC group) were recruited. The intima-media thickness (IMT), the inner diameter and the perfusion of dorsal artery of foot were measured by using high-frequency ultrasonograpy. Meanwhile, the parameters of vascular elasticity, including stiffness parameter (beta), pressure-strain elastic modulus (Erho), arterial compliance (AC), augment index (AI), and pulse wave conducting velocity (PWVbeta) were detected by means of echo-tracking technique. The results showed that no significant difference was found in the IMT, systolic diameter (Ds), diastolic diameter (Dd) and peak systolic velocity (PSV) between T2DM and NC groups. Erho and PWVbeta were increased, and AC was decreased in T2DM group as compared with those in NC group with the differences being significant (P<0.05 for all). There was no significant difference in beta and AI between T2DM and NC groups. It was concluded that high-frequency ultrasonography in combination with echo-tracking technique is sensitive and non-invasive, and can be used for early detection of sclerosis of the lower extremity artery in patients with type 2 MD.

Long-term prognosis of diabetic patients with critical limb ischemia: a population-based cohort study

OBJECTIVE

To evaluate the long-term prognosis of critical limb ischemia (CLI) in diabetic patients.

RESEARCH DESIGN AND METHODS

A total of 564 consecutive diabetic patients were hospitalized for CLI from January 1999 to December 2003; 554 were followed until December 2007.

RESULTS

The mean follow-up was 5.93 +/- 1.28 years. Peripheral angioplasty (PTA) was performed in 420 (74.5%) and bypass graft (BPG) in 117 (20.6%) patients. Neither PTA nor BPG were possible in 27 (4.9%) patients. Major amputations were performed in 74 (13.4%) patients: 34 (8.2%) in PTA, 24 (21.1%) in BPG, and 16 (59.2%) in a group that received no revascularization. Restenosis occurred in 94 patients, bypass failures in 36 patients, and recurrent ulcers in 71 patients. CLI was observed in the contralateral limb of 225 (39.9%) patients; of these, 15 (6.7%) required major amputations (rate in contralateral compared with initial limb, P = 0.007). At total of 276 (49.82%) patients died. The Cox model showed significant hazard ratios (HRs) for mortality with age (1.05 for 1 year [95% CI 1.03-1.07]), unfeasible revascularization (3.06 [1.40-6.70]), dialysis (3.00 [1.63-5.53]), cardiac disease history (1.37 [1.05-1.79]), and impaired ejection fraction (1.08 for 1% point [1.05-1.09]).

CONCLUSIONS

Diabetic patients with CLI have high risks of amputation and death. In a dedicated diabetic foot center, the major amputation, ulcer recurrence, and major contralateral limb amputation rates were low. Coronary artery disease (CAD) is the leading cause of death, and in patients with CAD history the impaired ejection fraction is the major independent prognostic factor.

Perioperative iloprost and endothelial progenitor cells in uremic patients with severe limb ischemia undergoing peripheral revascularization

The incidence of severe limb ischemia (SLI) is high among haemodialysis (HD) patients. Limb rescue rate after surgical revascularization is relatively poor compared with patients with normal renal function. Prostanoids are an interesting category as adjuvants to revascularization. New vessel growth develops not exclusively by proliferation of endothelial cells in vascular extremities but also by cells mobilized from the bone marrow (HSC), transformed into endothelial progenitor cells (EPC) contributing to both re-endothelialization and neovascularization. Basal number of HSC and EPC is significantly reduced in HD patients and correlated with a subsequent defective neovascularization. The aim of this study was to evaluate the effects of perioperative treatment with iloprost in uremic patients with acute ischemia of lower limbs, undergoing surgical revascularization, on endothelial progenitor cells, hypothesizing a possible biological mechanism induced by the prostanoids. A search was also made for vascular remodeling processes through the analysis of the concentrations of soluble adhesion molecules (i-CAM, v-CAM, e-selectin), biochemical markers of endothelial activation. Thirty HD patients with SLI undergoing peripheral revascularization were enrolled (15 were treated with iloprost and 15 with a placebo). Iloprost was administered as an intra-arterial bolus of 3000 ng over 1 to 3 min immediately after revascularization and in the same affected artery. Serum samples were taken before revascularization (T0), at 6 (T6) and 24 h (T24) after infusion to measure sICAM-1, sE-selectin, and sVCAM-1, and for quantification of HSC and EPC. Progenitors were identified by specific surface markers CD34+, CD133+ and VEGFR2+. Count was conducted using PROCOUNT performed in a TRUCOUNT tube and with a FACSort flow cytometer. Before revascularization, all patients showed a decreased number of HSC and EPC. After 6 h, HSC augmented significantly compared with T0 in both groups. The iloprost group attained a significant increase compared with the placebo group. HSC levels reduced drastically at T24. EPC augmented significantly compared with basal level after 24 h. In the iloprost group, the increase was considerable compared with the placebo group. A close negative correlation, assessed by Pearson coefficient (r), was found between HSC and EPC at T24 in the iloprost group (R = 0.82 P < 0.01). Adhesion molecules had increased levels at T6 and T24 in both groups. Moreover, a close positive correlation, assessed by Pearson coefficient, was found between EPC and adhesion molecules in both groups but the iloprost group maintained a better statistical association. Revascularization stimulated HSC and EPC release from bone marrow but at a different time: HSC increased suddenly at 6 h and diminished to a minimal amount at T24, conversely, EPC increased significantly only at T24. Iloprost treatment was able to amplify this mechanism validating recent findings (North TE et al., [31]). Adhesion molecules as markers of endothelial activation and vascular development confirmed this tendency.