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Interventional Radiology for Treating PAD
Syed Furqan Zaidi, M.D., details how iterventional radiology is used to treat chronic PAD, deep venous thrombosis, acute arterial thromboembolism and pulmonary embolism.
Interventional radiologists offer the most in-depth knowledge of the least invasive treatments available, coupled with diagnostic and clinical experience across all specialties. As the inventors of angioplasty and the catheter-delivered stent, first used in the legs to treat peripheral arterial disease (PAD), interventional radiologists pioneered minimally invasive modern medicine.
Advanced interventional radiology is used to treat chronic PAD as well as deep venous thrombosis, acute arterial thromboembolism and pulmonary embolism. Currently, the main indications for an interventional procedure in PAD patients include:
- claudication interfering with work or lifestyle refractory to conservative measures such as exercise therapy
- limb salvage in patients with severe ischemia manifested by pain at rest, nonhealing ulcers, infection or gangrene.
According to the Society of Interventional Radiologists, percutaneous transluminal angioplasty of the iliac arteries is associated with better long-term success rates than femoral angioplasty. Published results vary, with five-year patency rates of iliac angioplasty ranging from 53% to 88%, compared with less than 60% five-year patency rate for femoropopliteal PTA in most series. Small vessels below the knee also may be successfully treated, but this is usually reserved for patients with limb-threatening ischemia. Focal lesions respond best to PTA, while long stenoses, tandem lesions and chronic occlusions respond less favorably.
In experienced hands, PTA has a high technical success rate, with approximately 90% of patients experiencing improvement in symptoms. Immediate causes of PTA failure include intimal dissection, elastic recoil of the vessel wall, and arterial rupture. Restenosis due to intimal hyperplasia and progression of atherosclerosis are the most common causes of late PTA failures.
Stents. The introduction of metallic endovascular stents has revolutionized the interventional treatment of lower extremity PAD, mainly in the aortoiliac arteries. Currently available stents are either balloon-expandable or self-expandable. Technical success and patency rates after iliac stent placement are better than after angioplasty alone, with no increase in complication rates.
The availability of stents allows for endovascular treatment of chronic arterial occlusions and disease of more extensive distribution than that amenable to angioplasty alone. The excellent clinical results and low complication rate of aortoiliac stent placement justifies its use in patients with intermittent claudication and severe obstruction, who in the past were not felt to warrant surgical bypass.
Stent-Grafts. Metallic stents covered with prosthetic material, or stentgrafts, represent a new development in interventional radiology. Such devices are able to exclude blood flow from the diseased vessel and have potential in treating thoracic, abdominal, and iliac artery aneurysms. Mycotic and pseudoaneurysms have also been treated, as well as cases of iliac artery rupture caused by angioplasty. While the standard of treatment of aortoiliac aneurysms has been surgical repair, stent-grafts provide a less invasive alternative and are fast becoming the standard of care.
Thrombolysis. Thrombolytic therapy, usually with the plasminogen activator TPA, is often used by the interventional radiologist in the treatment of PAD patients. The percutaneous management of acute thrombosis and limb ischemia in the peripheral arteries is well established, and thrombolytic therapy is a common treatment for thrombosed bypass grafts. Chronic arterial occlusions in the legs are usually treated surgically or, in the iliac arteries, with primary stent placement. To minimize the risk of hemorrhagic complications, patient selection and management, as well as method of delivery, are critical when thrombolytic therapy is contemplated.
Catheter-directed thrombolysis, an interventional radiology treatment that uses targeted image-guided drug delivery with multisidehole infusion catheters, is being successfully used for treatment of acute thromboembolism. These techniques can be used in native arteries as well as occluded lower extremity bypass grafts. Thrombolytic techniques combined with angioplasty can safely revascularize regions of ischemia with a low rate of complications and avoids open surgery which can be risky in the setting of acute ischemia.
Catheter-directed thrombolysis saves lives and should be considered a first-line treatment option for massive pulmonary embolism. Awareness of its safety and effectiveness needs to be raised among both the general public and the medical community. IVC filter placement is also an option for PE prophylaxis or cases where anticoagulation is contraindicated for treatment of DVT.
Interventional radiology is an exciting field that is changing the standard of care for patients. We work closely with all specialties to provide minimally invasive treatments as an alternative or adjunct to medical and surgical treatment.
MD News January/February 2010