None listed
Conditions
Brief summary
Peripheral Arterial Disease (PAD) is characterised by blockages in the large arteries of the lower limbs. Chronic reductions in leg blood flow leads to microvascular impairment, including a reduction in muscle capillary density. These macro and microvascular impairments are independently associated with a severe reduction in functional (walking) ability. Patients are limited during daily activities by leg muscle pain and discomfort (claudication), and many develop signs of severe critical ischaemia, including rest-pain, tissue ulceration and gangrene. Lower limb revascularization procedures improve claudication symptoms by improving limb blood flow, but do not address the microvascular impairment, and do not fully restore functional capacity. However, when revascularisation procedures are combined with exercise therapy, greater gains are made in functional capacity without further change in large-artery blood flow. Based on evidence that supervised exercise therapy induces skeletal muscle capillary growth, and gains in functional capacity are related to increased muscle capillarisation, we hypothesise that the combination of revascularization plus post-operative supervised exercise therapy will lead to further improvements in outcomes (e.g. exercise tolerance and skeletal muscle microcirculation) compared to revascularisation alone. Therefore, this study aims to compare the efficacy of lower limb revascularisation plus supervised exercise therapy, with revascularisation alone, for improvement of walking capacity and skeletal muscle blood flow in PAD patients. This study will be conducted at the University of Sunshine Coast and the Department of Cardiology at Nambour General Hospital. Patients with PAD and symptoms of intermittent claudication, who are scheduled to undergo lower limb revascularisation, will be randomly assigned to one of two interventions at study entry: (1) standard post-operative care and monitoring (standard care) or (2) standard post-operative care plus an 8-week supervised exercise therapy program. Primary outcome measures will include walking capacity (6 minute walking distance) and calf muscle microvascular blood flow (using contrast-enhanced ultrasound [CEU]). Secondary outcomes will include i) leg muscle function (plantar-flexion strength and fatigue), ii) ankle brachial index, iii) arterial stiffness (augumentation index and carotid-femoral pulse wave velocity), iv) brachial and femoral artery function (flow mediated dilation) and v) leg blood flow (using venous occlusion plethysmography [VOP]). All parameters will be assessed in the limb undergoing revascularisation. Outcome measurements will be performed at baseline prior to revascularisation, then repeated following full recovery from revascularisation (2-6 weeks post-procedure), and then again at the completion of the 8 week post-operative intervention.
Interventions
Standard post-operative care plus supervised exercise therapy
The revascularisation intervention will be delivered by vascular surgeons at Nambour General Hospital. Revascularisation performed on the participant includes both open surgery and endovascular procedures. This will be personalised to each participant as considered necessary for optimal treatment by the vascular surgeon.
Following revascularisation, all patients will receive standard care that is based on international PAD management
Standard post-operative care plus supervised exercise therapy The revascularisation intervention will be delivered by vascular surgeons at Nambour General Hospital. Revascularisation performed on the participant includes both open surgery and endovascular procedures. This will be personalised to each participant as considered necessary for optimal treatment by the vascular surgeon. Following revascularisation, all patients will receive standard care that is based on international PAD management guidelines, including educational material with an emphasis on physical activity, smoking, and diet (Norgren et al. 2007). The vascular surgeon and the general practitioner of each participant will be sent a letter immediately after revascularisation and at 6-10 weeks after revascularisation, requesting that they adhere to clinical guidelines and targets (Norgren et al. 2007) (which will be outlined) so that all patients receive standardised care. Patients allocated to the exercise intervention group will undergo an 8-week supervised exercise training program, commencing within six weeks after the revascularisation procedure (within two to six weeks post-revascularisation, depending on the vascular procedure completed and clearance to commence the study intervention by the patient’s vascular surgeon). The exercise therapy intervention will be supervised by researchers (accredited physical therapists) at the University of the Sunshine Coast. Patients will attend group exercise sessions (3 sessions per week on non-consecutive days). Each session will include a combination of treadmill-walking and plantar-flexion exercise (both legs) as per recommended guidelines (Askew et al. 2014). Treadmill walking will consist of 20 min of intermittent walking that will be progressively increased in duration from 2.5 min in the first week, to 10 min in the last. Patients will walk at an intensity corresponding to the onset of mild-moderate claudication (e.g. 3-4 out of 5 in the claudication rating scale, where 0 = no pain and 5 = maximum pain). After the walking training, each patient will perform plantar flexion exercise using an isometric plantar flexion dynamometer. Participants will be seated with their hip and knee flexed, and with their foot resting on a foot-plate, and will perform three bouts of 5-min unilateral isometric contractions (2 s contraction: 3 s recovery) with each leg. Plantar-flexion exercise will be progressively increased in intensity from 40% of patient’s maximal force in the first week, to 70% of their maximal force in the last. Adherence to the supervised exercise therapy will be recorded by the investigators responsible for the delivery as the total number of visits recorded. Efforts to improve exercise adherence include group exercise sessions. If participants are unable to complete a bout of exercise they will be offered a 30 second rest period and the opportunity to complete the bout after the rest. Patients will be required to attend at least 85% of sessions (=21 sessions) for successful completion of the supervised exercise program.
Sponsors
University of the Sunshine Coast
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used) (Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
All
Age
40 Years to 90 Years
Healthy volunteers
No
Inclusion criteria
1. Patients scheduled for lower limb revascularisation, including open surgery (e.g. bypass), an endovascular procedure, or a hybrid procedure (e.g. endarterectomy plus angioplasty); 2. Documented diagnosis of PAD based on symptoms (claudication or critical limb ischaemia), an ABI < 0.90, and imaging evidence of a significant (>50%) stenosis in at least one lower-limb arterial segment; 3. Stable medication and treatment regimen (>3 months); 4. Physician-assessed ability to undertake the intervention and exercise testing.
Exclusion criteria
1. Not able to walk independently prior to revascularisation, or walking capacity is limited by symptoms not related to PAD (including neuropathy); 2. Have had or are undergoing a significant amputation (e.g. forefoot, leg) that is expected to limit ability to walk independently after surgery; 3. Exercise testing is contraindicated for reasons such as unstable angina, uncontrolled hypertension (>160/100), limiting venous disease or uncontrolled cardiac dysrhythmias; 4. Current or planned involvement in a supervised exercise rehabilitation program.
Outcome results
None listed