Endovascular Therapy: Principles of Peripheral Interventions
Contents:
In contemporary practice, however, surgery is commonly reserved for failure of EVT. Procedure planning should start the moment the decision has been made to perform invasive angiography and revascularization of an ischemic territory. For aortoiliac disease, CTA is a very useful tool.
Adequate local anesthesia, proper conscious sedation, and positioning on the angiography table are very important first steps. Ultrasound-guided access see US-guided access chapter is associated with lower access site complications and we always employ this technique. Therapeutic intensity anticoagulation IV heparin or bivalirudin. Administer first dose prior to positioning the working sheath across the aortic bifurcation; earlier if the sheath is noted to be occlusive.
When heparin is used, we aim for a target activated clotting time ACT of to seconds. Generally, address any inflow disease during the initial procedure, especially when the indication is claudication. For critical limb ischemia CLI , both inflow and outflow vessels need to be addressed.
See Table 2 for definitions of CLI. The goal in the periphery is relieving hemodynamically significant stenosis, not angiographic perfection. For claudicants, we recommend medical management and a walking program for exercise; proceed to revascularization only when the symptoms are severe and refractory to medical therapy or prohibit the successful participation in a meaningful exercise program.
Determine need for additional invasive diagnostic evaluation: Such as intravascular ultrasounds IVUS , and additional angiographic views with specific angulation to better lay out vessels of interest and to determine collateral flow patterns. Look for the presence of chronic total occlusions CTOs: These are common in patients presenting to the peripheral angiography suite. Treating CTOs is a time, radiation, contrast, effort, and resource intensive endeavor.
Verify the need for adjunctive and niche devices: Such as atherectomy or thrombectomy devices, emboli protection devices EPD , and reentry devices. Complex aortoiliac lesions frequently require IVUS evaluation to better assess the anatomy and guide the intervention. When the hemodynamic significance of an angiographic finding is in doubt, perform a translesional pressure gradient assessment at rest and with induced hyperemia downstream of the lesion. Self-expanding stents SESs are favored for treating markedly tortuous vessels and long lesions, when antegrade approach is used and for the external iliac arteries.
Stent grafts are usually reserved for aneurysmal segments, vessel rupture, and selected restenotic lesions.
Hybrid combined open surgical and EVT approach for complex inflow disease is well established with excellent outcomes. Occlusion predominates over stenosis in this space and involvement of the distal runoff vessel is common. Factors that may unfavorably influence EVT success in this segment: This territory is uniquely subjected to complex mechanical forces. Stent fractures are a consequence of such forces.
Stent fractures are commonly associated with in-stent restenosis in this segment.
General description of procedure, equipment, technique
Ostial SFA lesions deserve surgical or hybrid procedure consideration to avoid disrupting the profunda femoris artery PFA origin. For lesions that start beyond the SFA origin, with an adequate 0. For popliteal lesions, stenting should be avoided. Options for such lesions include debulking techniques with or without EPD or using flexible stent. Factors adversely associated with successful CTO crossing and subsequent long-term patency are lesion length, severe calcifications, higher TSAC II score, absence of vessel tapering i.
Decide the crossing strategy: Intraluminal crossing is always preferred but often is not feasible. Several recanalization devices have been introduced in recent years to assist with crossing CTOs:.
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Excimer laser fiberoptic catheters: The Wildcat device Avinger, Inc. The tip may be rotated manually or with a hand-held motorized unit to assume both passive wedges in and active wedges out configurations to traverse the CTO. The traditional with a combination of a looped, J-tip hydrophilic guidewire 0. Subintimal SI strategy as the primary mode of crossing is preferred when the occlusion is very long, mostly atherosclerotic no thrombus or heavy calcifications and, especially, when the distal target vessel is of good quality.
In our practice we use a combination of 0. Therefore, dedicated reentry devices have been dedicated to address this limitation: One port houses a hollow-core nitinol needle and an integrated element phase-array IVUS device, which is connected to the Volcano s5i Imaging System console Volcano Corp.
Reentry is guided by IVUS images. It is reasonable to primarily stent long lesions as the risk of restenosis is high.
Endovascular Therapy: Principles of Peripheral Interventions
In our practice we adopted a PTA first strategy and generally resort to stenting when necessary "bailout strategy". We are awaiting the results of several large trials currently evaluating drug-eluting balloons and stents for longer de novo and restenotic lesions. The move towards more uniform definitions and endpoints in the peripheral space is certainly an important step in the right direction. Successful endovascular therapy EVT of CLI requires addressing inflow as well as outflow vessels to establish in-line pulsatile flow to the ischemic wound.
Primary patency is less important in this space unless extensive tissue loss is present average time to healing lower extremity ischemic wounds is 6 to 10 months. Besides revascularization, management of CLI patients, particularly those presenting with ischemic wounds requires multidisciplinary team of wound care specialists, podiatrists, orthotists, prosthetists, and infectious and vascular experts. The success rate of tibial interventions has improved over the past few years and is quickly becoming the initial treatment strategy in most CLI patients.
Two major factors contributed to this: The availability of dedicated below-the-knee BK interventional tools, including wires and balloons longer, hydrophilic-coated with improved pushability and trackability and lower crossing profiles , BK drug-eluting balloons, BK stents, and low-profile atherectomy devices. Thrombotic lesions and using excisional atherectomy are associated with a high incidence of distal embolization.
Table of contents Reviews Features Editors. Verify the need for adjunctive and niche devices: While technical success and short-term and medium-term patency rates achieved with these traditional modalities have been promising, long-term patency rates, especially in the treatment of femoropopliteal disease, have proven disappointing. Femoropopliteal interventions Outcomes are related to lesion parameters length, complexity, calcifications, inflow and outflow status , patient-related risk factors, and compliance complete smoking cessation, presence of diabetes, walking exercise program, atherosclerotic risk factor control PTA, especially when an excellent result is achieved, has acceptable patency rates and remains the initial procedure for most patients Stenting improves outcomes when revascularizing chronic total occlusions or when flow-limiting dissections or suboptimal luminal gain secondary to recoil or calcification are noted Atherectomy strategies may improve the vessel response to angioplasty and increase allow successful stenting when necessary Tibial below-the-knee interventions: Several recanalization devices have been introduced in recent years to assist with crossing CTOs:.
Distal emboli may in these situations shut down distal outflow and cause acute limb ischemia, particularly when the runoff vessels are deemed poor. Several challenges continue to hinder applying EPD to the lower extremities. The diffuse nature of PAD and the common involvement of distal vessels leaves fewer segments appropriate to use as a landing zone.
Description
Traversing the device through calcific stenotic lesions and tortuous vessels imposes the risk of damage or entrapment during delivery and retrieval, especially after it had been filled with liberated debris. Antegrade access direct entry to the SFA is advocated in tibial intervention.
It has the following advantages: Obtaining high-quality informative angiographic images is critical when treating the tibial space. Usual views to include anteroposterior and ipsilateral oblique. Angulated projections cranial and caudal should be obtained to layout the vessels, particularly bifurcation points, and to accurately determine target lesions. To avoid damaging the outflow in case EVT fails and surgery is sought. To avoid vessel dissection, which can turn the case from CKLI to acute limb ischemia: Accurately size the long balloons.
E-books are non-returnable and non-refundable. Added to Your Shopping Cart. Description If you are one of the many physicians from different specialty disciplines who perform endovascular interventions then this practical reference will help you to develop your endovascular skills and encompass them into daily practice. Table of contents Reviews Features Editors. General Principles of Endovascular Therapy.
Basic Science of Endovascular Therapy.
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