Lower extremity arterial occlusive disease (LEAOD) is mainly caused by lower extremity atherosclerotic disease and diabetic peripheral vasculopathy. In recent years, with the development of the economy, the incidence of type 2 diabetes has been increasing. Type 2 diabetic peripheral vascular disease is often combined with atherosclerotic vasculopathy, which is an important component of LEAOD. Zhang Tong, Department of Peripheral Vascular Disease, Xiyuan Hospital, Chinese Academy of Traditional Chinese Medicine
When patients with LEAOD have severe limb-threatening ischemia due to arterial stenosis and occlusion that affects the blood supply to the end of the limb, hemodynamic reconstruction should be performed to improve the blood supply to the lower limb and save the ischemic limb. Reconstruction includes endoluminal angioplasty and surgical bypass grafting; broadly speaking, endoluminal angioplasty includes balloon dilatation angioplasty, balloon cutting angioplasty, cryovascular angioplasty, directional spot fast resection, circumferential spot fast spin resection, laser spot fast resection and stent placement. Intraluminal angioplasty has been widely used for the treatment of LEAOD because of its small trauma, fast postoperative recovery, precise efficacy and repeatable operation.
I. The treatment purpose of intracavitary angioplasty for LEAOD is to reconstruct the blood flow from the lower extremity directly to the plantar aspect of the foot; its clinical treatment objectives are: ① to improve symptoms such as ischemic pain and improve the quality of life; ② to establish the blood supply directly to the damaged part of the foot and promote the healing of foot ulcer; ③ to preserve the function of the limb and reduce the amputation plane.
II. Indications and contraindications for LEAOD intracavitary treatment.
When the degree of ischemia is assessed above Fontaine grade II, i.e., clinical ischemic symptoms such as intermittent claudication, or severe limb ischemia (resting pain or tissue loss) with limited quality of life and reduced mobility, angiography, MRA or CTA, arterial Doppler ultrasound, etc. should be performed on the ischemic limb to clarify the lesion site, and hemodynamic reconstruction including endovascular treatment should be performed. Among the above-mentioned vascular morphological examinations, if the luminal stenosis exceeds 50% or is occluded, regardless of the length and shape of the lesion, it is an indication for revascularization. Diabetic patients often do not have typical ischemic pain due to combined peripheral neuropathy, and peripheral vascular disease is the main cause of diabetic foot, so some experts suggest that diabetic foot is also an indication for angiography and, if necessary, endoluminal treatment.
There are no absolute contraindications to endoluminal therapy. It is generally accepted that endoluminal therapy is contraindicated in patients with NYHA cardiac function class III or IV, or in patients with unstable hemodynamic parameters. In addition, allergy to contrast agents, intolerance to antiplatelet agents or heparin, and renal insufficiency are relative contraindications.
Similarities and differences between intracavitary treatment strategies for atherosclerosis and diabetic peripheral vasculopathy.
Comparing from the pathological point of view, atherosclerotic lesions are characterized by endothelial lipid deposition, inflammatory cell invasion, and discontinuous intimal calcification; mesothelial involvement, elastic fiber fracture, and smooth muscle cell proliferation leading to loss of wall elasticity; diffuse atheromatous plaques are asymmetrically distributed and mostly eccentric; lesions mainly involve large and medium-sized arteries. In contrast, diabetic peripheral vascular lesions are characterized by invasion of lipids and macrophages into the arterial mesothelium, calcification of connective tissue degeneration, appearance of osteoblasts and formation of circular calcium plaques, resulting in centripetal thickening of the vessel wall and loss of vessel wall elasticity; the lesions mainly involve small and medium-sized arteries. In terms of lower extremity arterial involvement, simple atherosclerotic lesions tend to involve the iliofemoral artery, whereas diabetic peripheral vascular lesions tend to involve the infrapopliteal artery and are often manifested as long-segment occlusive lesions of multiple arteries. From the perspective of clinical symptoms, because diabetic peripheral vasculopathy and peripheral neuropathy often coexist, these patients have relatively heavy objective lesions with mild or even asymptomatic subjective discomfort, and the history is missing the intermittent claudication period, and resting pain, tissue defects, ulcers and even gangrene are already present at the time of consultation (Table 1). Therefore, the strategy of intraluminal treatment for patients with diabetic peripheral vasculopathy is different (Table 2).
Table 1 Comparison of clinical characteristics of diabetic peripheral vasculopathy and simple atherosclerosis
Diabetic peripheral vasculopathy
Atherosclerosis alone
Intermittent claudication
Rare
Common
Aortoiliac artery lesion
rare
Common
Infrapopliteal artery lesions
Common
Few
Thrombosis
Few
General
Effectiveness of treatment of suprapopliteal lesions
Limited or no
Effective
Deep femoral artery angioplasty
Unimportant
Effective
Intervention for subacromial lesions
Must
Rarely necessary
Risk of amputation
Very high
Low
Infection and necrosis
Common
Rare
Table 2 Comparison of Intraluminal Treatment Strategies for Diabetic Peripheral Vascular Lesions and Atherosclerosis
Diabetic peripheral vasculopathy
Atherosclerosis
Intraluminal intervention indications
Clinical indications
Mild discomfort and mild intermittent claudication
Moderate to severe interstitial claudication
Vascular morphologic indications
Asymptomatic, ≥50% diameter stenosis
Asymptomatic, ≥70% diameter stenosis
Symptomatic, ≥50% diameter stenosis
Intervention objectives
To improve symptoms; to promote ulcer healing; to preserve limb and restore motor function
Improvement of symptoms mainly
Target vessels
Anterior tibial, posterior tibial, peroneal, dorsalis pedis and
plantar arch arteries
Iliofemoral artery
Accuracy of blood flow reconstruction
Selective intervention according to the area of arterial supply in the foot lesion
Selection of interventions according to symptoms and degree of stenosis
Reconstruction form
Direct linear flow to the foot
Allowing distal collateral flow from the proximal trunk
Stent placement
Less
Common
Clean drainage, amputation
Often requires one-stage treatment
Rarely
Re-intervention
Often requires
rarely
Status of endovenous therapy
Preferred and currently most effective
First choice when conservative has failed
Sometimes open surgery is necessary
IV. The effectiveness of endoluminal therapy is evaluated in three main aspects.
Assessment of the degree of improvement of clinical ischemic symptoms and observation of endpoints: ① Observation of clinical symptoms, including prolongation of claudication distance, relief or disappearance of resting pain, limitation of ulceration or gangrene, and gradual wound healing. In addition, semi-quantitative analysis of the above-mentioned manifestations, such as assessment of the effect of intraluminal treatment using Rutherford grading criteria and/or ABI testing, is required. ② Observe the effect on the amputation rate. Clinically, amputations above the ankle joint are defined as major amputations, while amputations below the ankle joint are considered minor amputations, using the ankle joint as the boundary. The aim of intracorporeal treatment is to reduce the incidence of major amputation and to preserve or improve limb function. ③ The incidence of disease- or surgery-related complications and mortality during the perioperative period, hospitalization, and long-term follow-up were analyzed to determine the pros and cons of surgical treatment.
Observation of indicators related to surgical operation: ① Technical success rate: defined as smooth operation and residual stenosis ≤ 30% after hemodynamic reconstruction. ② Long-term vascular patency rate: The vascular patency rate was judged by angiography or Doppler ultrasound and other tests during the follow-up. Since the determination of patency is influenced by the detection method and the observer’s personal experience, the Binary restenosis rate is currently advocated to reflect the incidence of long term restenosis. (iii) Analysis of the rate of repeat endoluminal treatment of the original target lesion.
Hemodynamic evaluation: Observation of ABI changes before and after surgery and postoperative follow-up is used to assess hemodynamic improvement. Immediate postoperative ABI testing indicated hemodynamic improvement if the measured value increased by more than 0.15 compared with the preoperative value, and continued hemodynamic improvement was indicated if the ABI value increased by more than 0.15 compared with the preoperative value at long-term follow-up without the need for repeat intracavitary treatment of the original target lesion. In some patients with diabetic foot, ABI testing may have some error, and toe pressure and pulse wave tracing can be tested to determine their hemodynamic changes.
V. Problems and prospects
1. Changes in indications for endovascular treatment of LEAOD.
With the advancement of technology, updating of instruments, and accumulation of treatment experience, the understanding of the specificity of diabetic peripheral vascular lesions has been updated, and the effectiveness of endoluminal treatment of diabetic peripheral vascular lesions has been substantially improved. The current treatment indications are relatively obsolete and have been confirmed by nearly 10 years of clinical practice to have problems such as overly strict indicators, narrow scope, single-mindedness, and lack of relevance. Some domestic and foreign experts have suggested that the indications for LEAOD, especially for diabetic peripheral vascular disease, should be moderately relaxed, which can benefit more patients.
2. Changes in the scope of application of endovascular luminal therapy LEAOD.
With the improvement of endoluminal therapy technology and equipment, the scope of application of endoluminal therapy has been gradually expanded, and now it has been selectively used in many centers for the treatment of TASC C and D lesions and has achieved good clinical results. Endoluminal therapy has similar limb preservation rates compared to surgical bypass surgery and is now recognized as the first-line treatment for lower extremity arterial stenosis and occlusive lesions.
3. Indications and strategies for stent placement.
remains the focal point of endoluminal treatment. The pros and cons of stent placement below the groin have been debated by experts, and because of the unsatisfactory long-term patency rate and high rate of secondary intervention, a series of issues such as whether to place stents, which type of stents to place, how to choose the placement location, and how to effectively prevent restenosis after placement need to be gradually resolved in future research practice. In the author’s opinion, a differentiated approach should be followed, and different indications and strategies should be formulated for the femoral N artery segment and the infrapopliteal artery segment, respectively. It is believed that with the continuous improvement of stents, such as the introduction of new products like biodegradable stents and biological stents, the above problems will be satisfactorily solved.
4. New progress of endoluminal treatment strategy.
The best strategy of endoluminal treatment is to open the occluded vessels and establish the arterial blood supply directly to the foot lesion.
The key to endoluminal treatment of occlusive lesions is the use of guidewires to pass through the occluded lesion and re-enter the true lumen. The application of ipsilateral paracentesis techniques, subendothelial techniques, and facilities dedicated to reentering the true lumen such as the Pioneer or Outback catheter have increased the success rate of treatment of occlusive lesions of the superficial femoral artery.
The infrapopliteal artery remains more difficult to treat due to its thin vessels, long occlusive lesions and lack of dedicated facilities. In recent years new materials such as Chronic total occlusion (CTO) specific guidewires, support catheters and balloons have been used to facilitate the passage of occlusive lesions in the infrapopliteal artery. There have also been new advances in operative techniques.
Retrograde access techniques.
The treatment of infrapopliteal artery occlusive lesions is usually performed using a cis-femoral access technique that allows the guidewire to pass proximally to distally through the occluded lesion; the reverse access technique, on the contrary, allows the guidewire to pass retrogradely from distal to proximal through the occluded lesion through a constructed retrograde access. Possible mechanisms for the retrograde passage of guidewires through occlusive lesions [1]: (1) due to hemodynamic effects, the distal end of the occlusive lesion is concave in the form of a luminal stump, from which the guidewire passes more easily; (2) the proximal and distal components of the occlusive lesion are different, with less fibrotic or calcified tissue in the distal lesion than in the proximal end; (3) the proximal end of the vessel is often divided into head and tail to (3) The proximal end of the vessel often divides into head-to-tail and side-to-side branches, and the guidewire can easily enter the side-branch by mistake when passing in a downstream direction.
The techniques to form a retrograde access include: ① Constructing a pedal-plantar loop: using the anatomical features of the dorsal and plantar arteries, a pedal-plantar loop is formed by retrograde passage through the anterior tibial and dorsal pedal arteries to the distal posterior tibial artery; conversely, a pedal-plantar loop is formed by retrograde passage through the posterior tibial and plantar artery arches, followed by retrograde passage through the dorsal pedal artery to the distal anterior tibial artery. loop. Using the loop, the guidewire can be passed retrogradely through the occluded lesion to treat occlusive lesions of the tibial artery [2]. (ii) The guidewire is passed through the intertibiofibular artery as a lateral branch or through a branch to form a loop (Trans-Collateral), using this loop to pass retrogradely through the occluded lesion [3] [4]. (iii) A retrograde access is established by puncture of the infrapopliteal artery or by skin incision to expose the artery and then puncture and place a tube [5].
Dual access technique with a combination of cascade and retrograde access.
Combining the prograde and retrograde access, when the prograde access is blocked through the occluded lesion, a guidewire and catheter can be placed retrograde via infrapopliteal artery puncture; the prograde and retrograde placed guidewires and catheters act as markers for each other in the vessel, taking advantage of the retrograde access technique or through the docking of the guidewire and catheter through the occluded lesion.
In conclusion, endoluminal treatment of arterial ischemic diseases of the lower extremities has a wide application prospect due to its safety, effectiveness and reproducibility of treatment, in today’s world of continuous improvement of equipment and devices and operational techniques.
REFERENCES:
1. Montero-Baker M, Schmidt A, Bräunlich S, et al. Retrograde approach for complex popliteal and tibioperoneal occlusions. J Endovasc Ther. 2008;15: 594-604
2. Manzi M, Fusaro M, Ceccacci T, et al. Clinical results of below-the-knee intervention using pedal-plantar loop technique for the revascularization of foot arteries J Cardiovasc Surg (Torino). 2009;50(3):331-337
3. Fusaro M, Agostoni P and Biondi-Zoccai G. “Trans-Collateral” angioplasty for a challenging chronic total occlusion of the tibial vessels: a novel approach to percutaneous revascularization in critical lower limb ischemia. Catheter Cardiac Interven. 2008;71:268-272
4. Graziani L and Morelli LG. Combined retrograde-antegrade arterial recanalization through collateral vessels: Redefinition of the technique for Cardiovasc Intervent Radiol. 2010;03 June; publish on line
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