Vascular Recanalization Techniques
This chapter is an overview of the techniques of percutaneous intervention for recanalizing stenotic or occluded vessels. The indications and results for peripheral vascular, renal vascular, and venous intervention are discussed in subsequent chapters.
As early as 1964, Dotter and Judkins reported on the use of coaxial catheters to restore flow to a gangrenous extremity.1 In 1974, Gruentzig and Hopff introduced a double-lumen balloon catheter that revolutionized the field of interventional radiology.2 Stents, which were introduced in the late 1980s, helped to improve the results obtained with angioplasty alone. A suboptimal angioplasty now can be converted to a successful procedure with the placement of a stent. Acutely thrombosed vessels can be treated with the judicious use of thrombolytic agents. Lesions uncovered after clot dissolution can be treated with balloon angioplasty. These recanalization techniques can be used immediately after the diagnostic arteriogram either via the same percutaneous access used for the diagnostic arteriogram or through a second access site, thus simplifying the procedure.
Diagnostic arteriography should be performed only after a complete vascular workup, including noninvasive testing. Patients should have clear indications for revascularization, which include rest pain, nonhealing ulcers, gangrene, or severe claudication failing attempts at conservative therapy (i.e., smoking cessation and a consistent exercise program).3–5
When treating patients with peripheral vascular disease, we choose to access the vascular system, when possible, through the common femoral artery contralateral to the symptomatic extremity. This approach facilitates angioplasty or thrombolysis using the original puncture and does not preclude performing a second percutaneous puncture of the symptomatic extremity once the pathology is defined. The Seldinger technique, using either a double-wall or single-wall needle, is used to enter the common femoral artery. It is extremely important to enter the common femoral artery below the inguinal ligament and above its bifurcation to limit complications such as retroperitoneal hematomas, pseudoaneurysms, and arteriovenous fistulae.6,7 Using fluoroscopy, the common femoral artery is entered in its course over the lower half of the femoral head. The inferior epigastric artery and the deep circumflex iliac artery are good anatomic landmarks for the position of the inguinal ligament because these vessels arise off of the most distal aspect of the external iliac artery. If a prior angiogram is available, it should be reviewed to note the position of these vessels. It is safe to assume, however, that the inguinal ligament does not dip below the midfemoral head in almost all cases. It is important to puncture the common femoral artery over the midfemoral head. Too high a puncture may lead to retroperitoneal hematomas secondary to an inability to achieve adequate compression, and too low a puncture may lead to an arteriovenous fistula because the artery and vein tend to overlie each other in this region.
When treating peripheral vascular disease, a bilateral femoral arteriogram is performed from the level of the renal arteries to the feet. Appropriate oblique views of the pelvis and groin must be obtained to exclude lesions at the bifurcations of the common iliac artery and common femoral artery. When evaluating the angiogram, one must take into consideration the patient’s history, physical examination, and noninvasive studies. If the angiogram does not correlate with these studies, additional views must be obtained to uncover lesions that may not be clearly evident on the original arteriogram.
Percutaneous transluminal angioplasty for peripheral atherosclerotic disease is best performed on short focal stenoses or occlusions in large vessels. Lesions longer than 10 cm are considered less likely to have good initial and long-term results.8,9 With the use of stents, however, even long lesions in the aortoiliac distribution can be treated successfully.10 Results in the femoropopliteal distribution are less rewarding; however, when dealing with shorter lesions, results are acceptable. Even tibial vessels can be treated with angioplasty; however, these vessels should be treated only for limb-salvage indications. When treating occlusions, one must be convinced that the occlusion is chronic. If the occlusion is relatively acute, the incidence of embolization resulting from a clot may be high. Therefore, if an occlusion is suspected to be less than 6 weeks old, a primary angioplasty without prior thrombolysis probably should not be performed.
If an aortic or iliac lesion is identified or suspected, pressures must be obtained above and below the lesion to document its hemodynamic significance. Any resting gradient is considered significant. If no resting gradient is present, a vasodilator such as 60 mg of papaverine or 100 to 200 μg of nitroglycerin should be administered intraarterially distal to the lesion in question. A peak systolic gradient of greater than 10 mm of mercury is considered significant.11 When the outflow is markedly obstructed (such as in the presence of both superficial femoral artery and profunda femoral artery disease), there may not be a demonstrable gradient, despite the presence of a high-grade stenosis. These lesions should be identified and treated. If a bypass is performed below a significant lesion, the bypass may be compromised as a result of inadequate flow. Iliac angioplasty and stent placement can be performed around the aortic bifurcation using the puncture site of the diagnostic arteriogram. In many circumstances, we choose to puncture the ipsilateral common femoral artery in a retrograde fashion. This approach allows for simultaneous arterial pressure measurements above and below the lesion and facilitates accurate straight-line stent placement at the origin of the common iliac artery, if necessary (Fig. 7-1).
All interventions should be performed through a vascular sheath. The sheath usually facilitates the intervention by allowing for rapid catheter exchange, easier post-procedure angiographic evaluation, and decreased patient discomfort in the groin; it is associated with a lower incidence of complications. All patients are routinely pretreated with aspirin as an antiplatelet agent. Although many physicians use intraprocedural anticoagulation with heparin, its value is unconfirmed, and excessive use of heparin may lead to a higher incidence of local complications such as hematomas and pseudoaneurysms. With the current advances of endoluminal closure devices, full anticoagulation is less problematic. Ideally, tight stenotic lesions should be crossed using road mapping. The best guidewire catheter combination to cross the stenosis depends on the lesion and the operator.
Long lesions, external iliac artery lesions, and occlusions also can be treated. The optimal percutaneous therapy for iliac occlusions has not yet been determined. These lesions have been treated with initial lysis and subsequent angioplasty or stenting of the underlying lesions. Other successful treatments include primary stenting of iliac occlusions12–15 (Fig. 7-2). The response to balloon angioplasty of longer lesions is often less than ideal. Suboptimal angioplasty or an occlusive dissection is not uncommon; therefore, many interventional radiologists would recommend stenting these lesions primarily (Fig. 7-3). A balloon-expandable stent (e.g., Palmaz-Schatz, Cordis, Johnson & Johnson Corp., New Brunswick, NJ, U.S.A.) (see Fig. 7-1B) an IntraStent (Intratherapeutics, St. Paul, MN, U.S.A.) (seeFig. 7-3) or a self-expanding stent such as the Wallstent (Boston Scientific Corp., San Ramon, CA, U.S.A) or Smart Stent (see Fig. 7-17D) (Cordis, Johnson & Johnson Corp., New Brunswick, NJ, U.S.A.) (see Fig. 7-17D) can be placed. Suboptimal angioplasty of ideal lesions also can be managed by placing a stent (see Fig. 7-1). After intervention, pressures should be obtained again to assess hemodynamically the adequacy of the intervention.11,16–18
Most complications of angioplasty can be managed nonoperatively. The most common complication is a hematoma, usually self-limited at the puncture site. Pseudoaneurysms can be treated definitively by using ultrasound-guided compression or percutaneous thrombin injection. In situ thrombosis or distal embolization during or after angioplasty can be treated with intraarterial thrombolytics, with suction thromboembolectomy using a guiding catheter (Fig. 7-4), or with the Possis Angiojet device (Possis Medical, Minneapolis, MN, U.S.A.). Obstructing flaps can be stented. Iliac rupture is a feared complication because these patients may require surgery to prevent exsanguination. Iliac rupture is suggested by the presence of continued pain after the angioplasty balloon is deflated and the presence of free extravasation of contrast after angioplasty. The angioplasty balloon should be immediately reinflated across the lesion to tamponade the rupture. The patient then can be considered for transfer to the operating room for repair of the vessel; alternatively, a covered stent (if available) can be delivered via the femoral access to exclude the rupture (Fig. 7-6).
Superficial Femoral and Popliteal Artery Intervention
Stenoses or occlusions of the superficial femoral artery and popliteal artery up to 10 cm long are considered amenable to balloon angioplasty. These lesions can be approached from the contralateral extremity by using the common femoral artery access created during the diagnostic arteriogram (Fig. 7-7). Using an “over-the-corner” sheath markedly facilitates the advancement of balloon catheters across lesions using the contralateral approach.