High risk and low prevalence diseases: Acute limb ischemia

Acute Limb Ischemia Presenting as a Clinical Conundrum: Stroke Mimic or Aortic Dissection?

Patients with atrial fibrillation and transthyretin amyloid cardiomyopathy (ATTR-CM) have been found to have a very high incidence of intracardiac thrombus and thromboembolic disease. Acute limb ischemia is a rare, highly morbid condition that may mimic other medical emergencies. An 88-year-old male with ATTR-CM presented with left sided hemiparesis and paraesthesia. Computed tomography scan and magnetic resonance imaging of the head was negative for stroke. Subsequent computed tomography angiography (CTA) of the chest was obtained due to an abnormal interarm blood pressure differential which was negative for acute aortic dissection but revealed simultaneous occlusions of the left axillary and common femoral arteries. These occlusions were presumed to be cardioembolic from a left atrial appendage thrombus concurrently visualized on CTA. This case highlights the importance of avoiding anchoring bias, and systematically reevaluating the differential diagnosis in cases where the initial workup is unrevealing. While an uncommon entity, simultaneous upper and lower acute limb ischemia should be considered in patients with atrial fibrillation and prothrombotic comorbidities, such as ATTR-CM.

LEARNING POINTS

Acute limb ischemia can mimic stroke and aortic dissection, requiring a broad differential diagnosis in patients with atrial fibrillation and transthyretin amyloid cardiomyopathy.A systematic vascular-anatomic approach helps identify embolic events when initial stroke imaging is negative.Acute ischemia may be indicated by lactic acidosis without hemodynamic instability, which should lead to additional vascular assessment.

HC-A solution limb perfusion alleviates liver damage induced by limb ischemia-reperfusion injury in pigs

BACKGROUND

The aim of the study was to explore a feasible method for alleviating limb ischemia-reperfusion injury (LI/RI) through the use of a high-concentration citrate solution (HC-A solution) for limb perfusion (LP).

METHODS

Eighteen pigs were divided into three groups: the Sham group, LI/RI group, and HCA group. The Sham group underwent exposure of the iliac artery and vein. The LI/RI group underwent tourniquet placement and clamping of the iliac artery and vein to simulate LI/RI. The HCA group received HC-A solution LP for 30 min through the left iliac artery below the level of blood flow occlusion based on the LI/RI group. Oxidative stress markers and inflammatory response markers were compared among the three groups.

RESULTS

Compared to the LI/RI group, the HCA group showed significantly lower levels of serum creatine kinase (CK), lactate dehydrogenase (LDH), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), aspartate aminotransferase (AST), and alanine aminotransferase (ALT), and significantly greater activities of serum superoxide dismutase (SOD) (p < 0.05). There were no significant differences in serum interleukin-6 (IL-6) or in muscle MDA, SOD, TNF-α, and IL-6 between the HCA group and the LI/RI group (p > 0.05). Compared to the LI/RI group, MDA, TNF-α, and IL-6 levels in the liver were significantly lower in the HCA group (p < 0.05), while SOD activities were not significantly different (p > 0.05). Histopathological examination revealed reduced skeletal muscle and liver damage in the HCA group compared to the LI/RI group.

CONCLUSIONS

HC-A solution LP can alleviate liver damage caused by LI/RI in pigs.

Misdiagnosis of Acute Limb Ischemia from Non-Vascular Specialists Results in a Delayed Presentation and Negatively Affects Patients' Outcomes

BACKGROUND/OBJECTIVES

Acute Limb Ischemia (ALI) is a vascular emergency which is accompanied by a significant risk of limb loss or even death. Rapid restoration of arterial perfusion using surgical and/or endovascular techniques is crucial for limb salvage. Undeniably, an accurate and prompt diagnosis is the first step to improve patient prognosis. The typical clinical presentation is not always present and the variety of symptoms may result in non-vascular specialists missing the diagnosis.

METHODS

In this single-center retrospective descriptive study, we reviewed all patients hospitalized between January 2018 and January 2024 for ALI. Patients who were initially misdiagnosed, causing a delayed diagnosis > 24 h, and who therefore did not receive timely treatment, were identified. Moreover, patients with a timely diagnosis of ALI who were treated in our institution during the same time period were collected.

RESULTS

Among 280 ALI patients, 14 were initially misdiagnosed. The median time from initial symptoms to definite diagnosis was 38.8 days (range 1.5-365). Several specialties such as orthopedic surgeons, neurologists, and general practitioners were involved in patients' initial assessment. Three patients underwent primary amputation due to irreversible ALI, while nine underwent revascularization and one conservative treatment. Thirty-day limb salvage rate was 9/14 and thirty-day mortality was observed in one patient. Secondary interventions were needed in 65% of these cases. Patients with a delayed ALI diagnosis, when compared to those with a timely diagnosis, presented a significantly lower limb salvage rate (65% vs. 89%, p-value = 0.02) and a significantly higher rate of reinterventions (65% vs. 18%, p-value < 0.001).

CONCLUSIONS

Many patients with ALI are primarily referred to non-vascular specialties. Misdiagnosed and mistreated ALI negatively affects outcomes.

Molecular Insight into Acute Limb Ischemia

Acute limb ischemia (ALI) is defined as a sudden reduction in blood flow to a limb, resulting in cessation of blood flow and, therefore, cessation of the delivery of nutrients and oxygen to the tissues of the lower limb. Despite optimal treatment to restore blood flow to ischemic tissues, some patients may suffer from ischemia/reperfusion (I/R) syndrome, the most severe complication after a revascularization procedure used to restore blood flow. There are multiple molecular and cellular factors that are involved in each phase of ALI. This review focuses firstly on molecular and cellular factors of arterial thrombosis, highlighting the role of atherosclerotic plaques, smooth muscle cells (SMCs), and cytokine which may alter key components of the extracellular matrix (ECM). Then, molecular and cellular factors of arterial embolism will be discussed, highlighting the importance of thrombi composition. Molecular and cellular factors of ischemia/reperfusion syndrome are analyzed in depth, highlighting several important mechanisms related to tissue damage, such as inflammation, apoptosis, autophagy, necrosis, and necroptosis. Furthermore, local and general complications of ALI are discussed in the context of molecular alterations. Ultimately, the role of novel biomarkers and targeted therapies is discussed.

The Impact of COVID-19 on Amputation and Mortality Rates in Patients with Acute Limb Ischemia: A Systematic Review and Meta-Analysis

Since the inception of the SARS-CoV-2 pandemic, healthcare systems around the world observed an increased rate of Acute Limb Ischemia (ALI) in patients with a COVID-19 infection. Despite several pieces of evidence suggesting that COVID-19 infection may also worsen the prognosis associated with ALI, only a small number of published studies include a direct comparison regarding the outcomes of both COVID-19 and non-COVID-19 ALI patients. Based on the above, a systematic review and a meta-analysis of the literature were conducted, evaluating differences in the incidence of two major outcomes (amputation and mortality rate) between patients concurrently affected by COVID-19 and negative ALI subjects. PubMed (MEDLINE), Web of Science, and Embase (OVID) databases were scrutinized from January 2020 up to 31 December 2023, and 7906 total articles were recovered. In total, 11 studies (n: 15,803 subjects) were included in the systematic review, and 10 of them (15,305 patients) were also included in the meta-analysis. Across all the studies, COVID-19-positive ALI patients experienced worse outcomes (mortality rates ranging from 6.7% to 47.2%; amputation rates ranging from 7.0% to 39.1%) compared to non-infected ALI patients (mortality rates ranging from 3.1% to 16.7%; amputation rates ranging from 2.7% to 18%). Similarly, our meta-analysis shows that both the amputation rate (OR: 2.31; 95% CI: 1.68-3.17; p < 0.00001) and mortality (OR: 3.64; 95% CI: 3.02-4.39; p < 0.00001) is significantly higher in COVID-19 ALI patients compared to ALI patients.