Neurostimulation: A Novel Option for Severe Peripheral Arterial Disease in Absence of Other Treatment Option

Abstract

Introduction - 14-20% of patients with critical limb ischaemia (CLI) may have had previous multiple interventions and exhausted all options of any further revascularization; some may have extensive disease with no easily treatable pathology (1) or are not fit for intervention. Both of these groups of patients are considered as having ‘end stage’ peripheral arterial disease (PAD) and major limb amputation may be the outcome. Amputation has a significant physical, mental, economic impact on an individual (2) and on society and would be best avoided if possible. Recent experiments have suggested that stimulation of afferent fibres of the Vagus Nerve may trigger the brain stem to achieve improved microcirculation in the extremities by arteriolar vasodilatation, thus improving blood flow in a critical or sub-critical limb (3). This study aims to evaluate whether treating patients with ‘End Stage’ PAD with Ducest Neurostimulator increases peripheral blood flow and thereby improves symptoms of severe claudication, reduces pain and reduces risk of major limb amputation. Methods - A pilot study with neurostimulation in 13 patients with ‘End Stage’ PAD where no further revascularization was an option; 12 male and 1 female, age ranges between 63-93 years with a mean of 75. All were treated with Ducest Neurostimulator implanted in fossa triangularis of the ear overlying afferent Vagus nerve fibres for a two 2 week period. Symptomatic improvement was recorded using visual analogue pain scores, increase in walking distance, and reduction or relief of rest pain. All patients had 2D and 3D duplex scan pre-treatment and post-treatment measuring tibial vessel diameter, flow volume, 3D volume, ankle pressure with ABPI and toe pressure with TBPI. Results - 9 patients have shown improvement in walking distance, with claudication distance improving in 3 patients from 30 metres to 200 metres, 4 patients with improvement of claudication distance from 50 metres to 100 metres, and 2 patients improving from 50 metres to 80 metres. Reduction of pain, improved quality of life and improved outcome on Visual Analogue pain Score were seen in 11 patients. 8 patients had reduction in rest pain with reduced analgesic intake and were sleeping better. 8 patients showed improvement in tibial flow volume ranging from a velocity increase of 4cm/sec to 97cm/sec. An increase in tibial vessel diameter were seen in 10 patients ranging from a diameter increase of 0.02cm to 0.16cm. Ankle pressure improved in 9 patients ranging from an increase of 10mm Hg to 40mm Hg, and toe pressure improved in 6 patients ranging from an increase of 7mm Hg to 60mm Hg. Procedures were well tolerated in all patients. Major limb amputation was avoided in 5 patients and one patient’s amputation was delayed by 5 months. Conclusion - This pilot study suggests that vagal neurostimulation improves peripheral circulation in patients with severe “end stage” PAD. Such patients receiving this treatment may experience improvement of symptoms and avoid major limb amputation. This technique has a definite role in the future management of such patients.