Critical limb ischemia

AG490 suppresses EPO-mediated activation of JAK2-STAT but enhances blood flow recovery in rats with critical limb ischemia

Background

Erythropoietin (EPO) has been demonstrated to enhance recovery in ischemic organs through enhancing angiogenesis. In this study, we used an experimental critical limb ischemia (CLI) rat model to reveal the underlying mechanisms and directly examine the benefits of the anti-apoptotic capacity of EPO in the acute phase of limb ischemia and following blood flow recovery.

Methods

To determine the role of the JAK2/STAT pathway in EPO-enhanced recovery after CLI, male Sprague-Dawley rats (n = 8 for each group) were divided into group 1 (normal control), group 2 (CLI treated with normal saline), group 3 (CLI treated with EPO), group 4 (CLI treated with AG490, a JAK2 inhibitor), and group 5 (CLI treated with EPO and AG490). Animals were sacrificed either at day 1 or day 14 and biochemical and histopathological examination of ischemic quadriceps were conducted.

Results

At day 1, EPO administration reduced expression levels of apoptotic indices and activated the JAK2/STAT pathway; this activation was inhibited by additional AG490 treatment. Furthermore, the decrease in the size of the infarcted area, as well as activation of ERK1/2 and JNK showed similar regulatory trends with EPO or AG490 treatment. Of Interest, EPO and AG490 in combination showed a synergistic effect, increasing expression levels of antioxidants (GR, GPx, NQO-1) and decreasing transcriptional levels of pro-inflammatory factors (TNF-α, NF-kB). At day 14, laser Doppler analysis showed that the blood flow recovery was enhanced by EPO, AG490, or combined treatment.

Conclusion

Although inhibition of the JAK2/STAT pathways reduces the anti-apoptotic effects of EPO in the early phase of CLI, the benefits of AG490 in anti-inflammation and anti-oxidation still play a positive role in enhancing blood flow recovery after CLI.

Serum nesfatin-1 is reduced in type 2 diabetes mellitus patients with peripheral arterial disease

Background

Nesfatin-1, recently identified as a satiety regulator, elicits an anti-atherosclerosis effect. Our study was designed to determine whether there is an association between serum nesfatin-1 and the development and severity of peripheral arterial disease (PAD) in patients with type 2 diabetes mellitus (T2DM).

Material/Methods

This cross-sectional study included 355 T2DM patients (200 without PAD and 155 with PAD).

Results

T2DM patients with PAD exhibited marked lower serum nesfatin-1 concentrations than those without PAD. Multivariable logistic regression analysis indicated an inverse association of serum nesfatin-1 concentrations with the development of PAD in T2DM patients (OR 0.008, 95% CI 0.002 to 0.028; P<0.001). Simple linear regression analysis showed a marked correlation between serum nesfatin-1 concentrations and body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR), C-reactive protein (CRP), and ankle-brachial index (ABI) in T2DM patients. By contrast, multivariable analysis showed only BMI and ABI as independent correlates of serum nesfatin-1.

Conclusions

Our study shows an association of serum nesfatin-1 concentrations and the development and severity of PAD in T2DM patients.

Effect of percutaneous transluminal angioplasty on tissue oxygenation in ischemic diabetic feet

Percutaneous transluminal angioplasty (PTA) has been performed as an alternative to bypass surgery for improving tissue oxygenation in ischemic diabetic feet because the former is less invasive than the latter. The purpose of this study was to evaluate the effect of PTA on tissue oxygenation in ischemic diabetic feet. This study included 29 ischemic diabetic feet, as determined by a transcutaneous oxygen pressure (TcPO(2) )<30 mmHg. The PTA was carried out in 29 limbs. The PTA procedure was considered successful, acceptable, and failed when residual stenosis was<30%, between 30 and 50%, and>50%, respectively. For evaluation of tissue oxygenation, the foot TcPO(2) was measured before PTA and weekly for 6 weeks after PTA. Immediately after PTA, 26 feet were evaluated as being successful and the remaining three as acceptable. Before PTA, the average foot TcPO(2) was 12.7 ± 8.9 mmHg. The TcPO(2) values were increased to 43.6 ± 24.1, 51.0 ± 22.6, 58.3 ± 23.0, 61.3 ± 24.2, 59.0 ± 22.2, and 53.8 ± 21.0 mmHg 1, 2, 3, 4, 5, and 6 weeks after PTA, respectively (p<0.01). The PTA procedure significantly increases tissue oxygenation in ischemic diabetic feet. The maximal level of tissue oxygenation was measured on the fourth week following PTA.

Critical limb ischaemia in a diabetic population from an Asian Centre: angiographic pattern of disease and 3-year limb salvage rate with percutaneous angioplasty as first line of treatment

Purpose:

Lower extremity amputation prevention (LEAP) is an ongoing program in our institution aimed at salvaging limbs in patients with critical limb ischemia (CLI). Patients in the LEAP program with reconstructible anatomy on initial Doppler imaging received either bypass surgery or percutaneous transluminal balloon angioplasty (PTA). We present the 3 year limb salvage rate and angiographic disease patterns in 42 consecutive diabetic patients with CLI who received PTA in 2005.

Methods and Material:

26 women and 16 men with diabetes between the ages of 45 and 91 years old (mean age, 70.8 years) received PTA in 2005. Presenting symptoms were rest pain (n = 22), pre-existing gangrene (n = 17), non-healing ulcer (n = 16) and cellulitis (n = 2). The aim of the PTA was to achieve straight-line flow from the abdominal aorta down to the patent dorsalis pedis or plantar arch, with limb salvage as the ultimate outcome. Failure of treatment was defined as any amputation above the level of a Syme’s amputation or the need for further surgical bypass. Technical success was achieved in 90% (38 out of 42 patients).

Results:

Limb salvage rates were 93% at 1 month, 87% at 3 months, 82% at 6 months, 78% at 1 year, 69% at 2 years and 66% at 3 years. Mortality was 17% (n = 7) at 3 years. Of the 13 patients with failed therapy, 3 underwent bypass, 9 had amputations and 1 had bypass followed by amputation. Four of the cases required further intervention due to worsening gangrene and infection, while the remaining was due to persistent rest pain. The rest of the 32 patients had no lower limb related issues at the end of 3 years, with improvement of the presenting symptoms. Patterns of treated segments were aortoiliac occlusions (n = 3), pure infrapopliteal disease (n = 3), femoropopliteal with at least 1 good infrapopliteal run-off vessel (n = 14) and combined femoropopliteal and infrapopliteal disease (n = 25).

Conclusion:

Involvement of infrapopliteal vessels that needs to be treated is common in Asian diabetics. While early limb salvage rates up to 1 year are similar, the 3 year limb salvage rates in Asian diabetics are lower than the western population.

A new rat model for thrombus-induced ischemic pain (TIIP); development of bilateral mechanical allodynia

Patients with peripheral arterial disease (PAD) commonly suffer from ischemic pain associated with severe thrombosis. However, the pathophysiology of peripheral ischemic pain is not fully understood due to the lack of an adequate animal model. In this study, we developed a new rodent model of thrombus-induced ischemic pain (TIIP) to investigate the neuronal mechanisms underlying ischemic pain. Ischemia was induced by application of 20% FeCl(2) onto the surface of the femoral artery for 20min. Induction of peripheral ischemia was confirmed by measurement of the concentration of Evans blue and by increases in the ischemia-specific markers, hypoxia-inducible factor-1 alpha and vascular endothelial growth factor in the ipsilateral plantar muscles. Ischemic pain, as indicated by the presence of mechanical allodynia, developed bilaterally and peaked at days 3-9 post-FeCl(2) application and gradually decreased through day 31. Systemic heparin pretreatment dose dependently suppressed ischemic pain, suggesting that thrombosis-induced ischemia might be a key factor in TIIP. Intraplantar injection of BMS-182874, an ET(A) (endothelin-A) receptor antagonist, at day 3 selectively blocked ipsilateral pain, indicating that ET(A) receptor activity mediated TIIP. Spinal GFAP expression was significantly increased by FeCl(2) and intrathecal injection of carbenoxolone (an astrocyte gap junction decoupler) at day 3 significantly reduced TIIP, suggesting that spinal astrocyte activation plays an important role. However, the anti-inflammatory agent, ibuprofen, did not affect TIIP. In conclusion, we have developed a novel animal model of TIIP that should be useful in investigating the pathophysiological mechanisms that underlie human peripheral ischemic pain.

Open bypass and endoluminal therapy: complementary techniques for revascularization in diabetic patients with critical limb ischaemia

The use of endovascular therapy (EVT) for lower extremity atherosclerosis is markedly increasing while open surgical bypass is in decline. The results of EVT for critical limb ischaemia (CLI) are difficult to evaluate, especially for patients with diabetes. To date, only one randomized, prospective trial has been published comparing EVT with open bypass for CLI. Although early costs and outcomes were equivalent or superior for EVT, after 2 years, surgery was associated with a significantly reduced risk of future amputation and death.Approximately, 40-50% of diabetic patients with CLI can be initially treated with EVT. Patients with Trans-Atlantic Inter-Society Consensus (TASC) A and B lesions should be treated endoluminally. EVT should be used with caution in patients with TASC C and D lesions; however, in selected patients, particularly if vein conduit is lacking and life expectancy is short, EVT is not unreasonable. For low-to-moderate risk patients with TASC C or D lesions, extensive tibial disease, and suitable vein conduit, surgical bypass remains the best limb preservation option. The primary therapeutic goals are relief of rest pain, healing of ischaemic lesions, and maintenance of functional status. Haemodynamic assessment is critical following both open and EVT for CLI and aids in determining the need for further revascularization; additional interventions are required in 20-30% of CLI patients depending on the degree of ischaemia, anatomical disease extent, and mode of initial therapy. At the University of Arizona, we currently recommend that TASC A and B CLI patients undergo EVT first. TASC C and D patients should undergo bypass unless available conduit is poor, surgical risk is prohibitive, or life expectancy is limited. CLI is a serious end-of-life condition given the sobering realization that only 50-55% of CLI patients are alive with an intact limb 5 years after initial presentation.

Angioplasty in Critical Limb Ischaemia: One-year Limb Salvage Results

Introduction: Lower extremity amputation prevention (LEAP) is an ongoing programme in our institution aimed at limb salvage in patients with critical limb ischaemia (CLI). Patients in the LEAP programme with reconstructible anatomy on initial Doppler imaging received either bypass surgery or percutaneous transluminal balloon angioplasty (PTA). We describe the 1-year limb salvage rates in 46 consecutive patients with CLI who received PTA in 2005. Clinical Picture: A total of 46 patients, 28 women and 18 men, between the ages of 40 and 91 years old (mean age, 70.8) received PTA in 2005. The most common presenting symptom was rest pain (n = 23), followed by pre-existing gangrene (n = 20), non-healing ulcer (n = 17) and cellulitis (n = 8). The majority of the patients (57%) had 3 to 4 risk factors. Diabetes mellitus (91%) and hypertension (80%) were the 2 most common risk factors. The patients were kept under surveillance for periods ranging from 12 to 21 months with a mean of 13.3 months, both clinically and with haemodynamic measurements [ankle-brachial index (ABI), toe pressure (TP) and digital-brachial index (DBI)]. Treatment: The aim of PTA is to achieve straight-line flow from the abdominal aorta down to either a patent dorsalis pedis or plantar arch with limb salvage as the ultimate goal. The patterns of the treated segments were as follows: aorto-iliac occlusions (n = 3), pure infrapopliteal disease (n = 5), femoropopliteal disease with at least 1 good infrapopliteal run-off vessel (n = 16) and combined femoropopliteal and infrapopliteal disease (n = 25). Technical success was achieved in 89% of patients (41 out of 46 patients). The most common cause of technical failure is the inability to cross long chronic total occlusions. Outcome: Paired T test was performed and showed statistically significant improvement in haemodynamic markers within the technically successful group. This included increase in the mean ABI from 0.62 (pre-angioplasty) to 0.91 (Day 1 post-angioplasty), an increase of 0.29 [95% confidence interval (95% CI), 0.1953 to 0.3875; P <0.001]. One year post-angioplasty, the mean ABI was 0.84, an increase of 0.22 (95% CI 0.1512 to 0.3121; P <0.001). There was also significant increase in the mean DBI of 0.17 from 0.23 to 0.41 (pre-angioplasty versus Day 1 post angioplasty – 95% CI of 0.1006 to 0.2433; P <0.001). In addition, significant increase in the mean TP of 28.2 mmHg from 36.8 to 63.2 mmHg (pre-angioplasty versus Day 1 post angioplasty – 95% CI, 18.493 to 37.939; P <0.001) was also noted. Of the 23 patients who presented with rest pain, total abolishment of symptoms was achieved in 21 patients (91%). Healing of pre-existing gangrene was attained in 15 patients (66%). Five patients subsequently received minor amputation for pre-existing gangrene. Clinical improvement in all the patients who presented with non-healing ulcers (n = 17) and cellulitis (n = 8) was attained. More importantly, all healed ulcers remained healed throughout the study period. The limb salvage rates were 93% at 1 month, 87% at 3 months, 82% at 6 months and 78% at 1 year. Conclusion: Angioplasty is a safe and effective limb salvage method in patients with CLI and has a high 1-year limb salvage rate. Key words: Angioplasty, Arterial occlusive diseases, Balloon, Lower extremity, Treatment outcome