High risk and low prevalence diseases: Acute limb ischemia

INTRODUCTION

Acute limb ischemia is a rare but serious condition that carries with it a high rate of morbidity and mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of acute limb ischemia, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Acute limb ischemia is defined as a sudden decrease in limb perfusion resulting in cessation of blood flow and nutrient and oxygen delivery to the tissues. This leads to cellular injury and necrosis, ultimately resulting in limb loss and potentially systemic symptoms with significant morbidity and mortality. There are several etiologies including native arterial thrombosis, arterial thrombosis after an intervention, arterial embolus, and arterial injury. Patients with acute limb ischemia most commonly present with severe pain and sensory changes in the initial stages, with prolonged ischemia resulting in weakness, sensory loss, and color changes to the affected limb. The emergency clinician should consult the vascular specialist as soon as ischemia is suspected, as the diagnosis should be based on the history and examination. Computed tomography angiography is the first line imaging modality, as it provides valuable information concerning the vasculature and surrounding tissues. Doppler ultrasound of the distal pulses may also be obtained to evaluate for arterial and venous flow. Once identified, management includes intravenous unfractionated heparin and vascular specialist consultation for revascularization.

CONCLUSIONS

An understanding of acute limb ischemia can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Extravascular findings on run-off MR angiography: frequency, location and clinical significance

OBJECTIVES

The aim of this study was to analyze the prevalence, location and clinical relevance of extravascular findings (EVFs) on magnetic resonance angiography (MRA) of the run-off vasculature.

METHODS

In this retrospective study, we analyzed run-off MRAs of 194 consecutive patients (45 women and 149 men, median age 68 years, IQR 58-74 years). Our patient cohort consisted predominantly of individuals with known (n = 165, 85%) or suspected (n = 15, 8%) peripheral artery disease (PAD). All MRA examinations were performed between 2012 and 2018 on a 3 Tesla MRI scanner using a standardized protocol. Two radiologists re-evaluated the MRA images to identify EVFs, which were classified into findings with major (category I), moderate (category II) and minor (category III) clinical significance.

RESULTS

A total of 501 EVFs were found in 172 of the 194 patients (89%). Twenty-seven findings (5%) were assigned to category I, 189 (38%) to category II and 285 (57%) to category III. 23 of 194 patients (12%) had at least one EVF with major clinical relevance (category I). Most of the 27 category I EVFs were observed in the soft tissues (n = 13, 48%). The remaining category I EVFs were found in the musculoskeletal (n = 7, 26%), urogenital (n = 4, 15%), lymphatic (n = 2, 7%) and gastrointestinal (n = 1, 4%) system. The majority of the category I EVFs were infectious (n = 14, 52%) or neoplastic (n = 10, 37%) pathologies.

CONCLUSIONS

Clinically relevant EVF can be encountered frequently on run-off MRA examinations. These results illustrate the importance of evaluating all organ systems when reporting MRA examinations, despite the clinical focus being the patients' vascular status.

Extravascular incidental findings in run-off CT angiography in patients with acute limb ischaemia: incidence and clinical relevance

AIM

To evaluate the incidence and clinical relevance of extravascular incidental findings (EVIFs) in CT angiography of the abdominal aorta and lower extremities (run-off CTA) in patients presenting with acute limb ischaemia (ALI).

MATERIALS AND METHODS

In this institutional review board-approved, retrospective study, 141 run-off CTA examinations conducted between 2005 and 2013 of patients (67 women, mean age 80 years; 74 men, mean age 69 years) presenting with clinical symptoms of ALI were re-evaluated by two radiologists (2 and 7 years of experience in interpreting run-off CTA). Imaging was conducted using 16- and 64-section CT systems. Image acquisition ranged from the costodiaphragmatic recess to the forefoot. The medical history form of each patient served as the standard of reference for assessment of incidence of EVIFs. CT morphology was assessed to assign EVIFs to one of three categories of clinical relevance: (I) immediate, (II) potential, and (III) no clinical relevance.

RESULTS

Thirty-eight patients had category I findings, including four patients (2.8%) with previously unknown malignancy and 67 patients with category II EVIFs. In total 473 extravascular EVIFs were found in 141 patients: 52 category I, 163 category II and 258 category III.

CONCLUSION

EVIFs with immediate clinical relevance are very common in run-off CTA in patients presenting with acute peripheral artery disease. Therefore, it is important to evaluate all body regions included in a CT examination carefully, even if the clinical focus is on vascular evaluation. The adequate classification of these EVIFs is required to avoid possible unnecessary diagnostic work-up with associated risks and costs.