Subintimal Angioplasty for Long SFA Occlusions With Critical Ischemia
Although this technique has yet to gain widespread acceptance, its popularity is growing, especially in high-risk patients.
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The technique of subintimal angioplasty was serendipitously developed in Leicester, UK in 1987 when, in the course of treating a 15-cm popliteal occlusion, a subintimal channel was accidentally created and balloon dilated. The authors recognized this occurrence and appreciated its potential for the therapy of arterial occlusive disease.1 That particular angioplasty remained patent for more than 9 years. The use of subintimal angioplasty for the treatment of occluded femoropopliteal arteries was first described by Bolia et al in 1989.2 Experience from a small number of centers in Europe and, more recently, in the US have reported promising results with this technique and its applications have been expanded to include crural and iliac arteries.3-7 Despite these positive experiences, the technique has not gained widespread acceptance, although it does appear to be gaining some popularity. This may be due a steep learning curve or skepticism regarding the procedure.
Patients with anatomically favorable lesions and/or severe medical comorbidities are usually considered for subintimal angioplasty. Anatomically favorable lesions are those in which there is suitable length of relatively normal artery both proximal and distal to the occluded segment, which permits the creation of the subintimal dissection plane and re-entry into the native lumen without potentially compromising major branch vessels during the procedure or reducing future bypass options.
Subintimal angioplasty can be performed using either an ipsilateral antegrade common femoral artery (CFA) puncture or a contralateral CFA puncture. When a contralateral puncture is used, subintimal angioplasty can be performed using a long 6F sheath placed over the aortic bifurcation. After arterial puncture and sheath placement by either approach, patients are systematically heparinized. An angled, 0.035? Terumo Glidewire (Terumo Medical Corporation, distributed by Boston Scientific Corporation, Natick, MA) and a supporting 5F KMP catheter (Cook Incorporated, Bloomington, IN) are used to create a subintimal dissection plane above the level of the occlusion. The wire is then advanced, and a loop will naturally form at the tip of the guidewire. The loop and catheter are then advanced through the subintimal plane until the occlusion is passed. The subintimal dissection plane has a characteristic resistance when entered, traversed, and exited.
Perhaps a more important indication that one is in the subintimal plane is the formation of the wire into a “wide loop.” When this wide loop is formed, the diameter of the loop at its distal end is larger than that of the artery’s native lumen. To fully appreciate this phenomenon, the wire must be imaged in a plane that is perpendicular to the loop. Finally, the wire will frequently take a course that seems to spiral around the lumen of the artery. This is because the path of least resistance rarely lies in the same longitudinal plane of the artery. This pattern gives the somewhat characteristic “spiral” pattern seen on completion angiography after successful subintimal angioplasty. Despite these strong predictors of subintimal wire position, the exact path of the wire cannot be controlled throughout the entire occluded segment. Because the technique is not performed under direct visualization, the interventionalist must rely on the fluoroscopic appearance of the wire and loop to confirm position in the subintimal plane.
A loss of resistance is often encountered as the wire re-enters the true lumen of the native artery distal to the occlusion. Recanalization is confirmed by advancing the catheter over the guidewire beyond the point of re-entry and obtaining an angiogram. In cases in which a contralateral puncture is used, an angioplasty balloon is inflated proximal to the lesion to stabilize the guidewire and allow the necessary force to enter and traverse the subintimal plane. The recanalized segment is then balloon dilated at 8-10 atm using an appropriately sized angioplasty balloon. The technique does not require the use of stents and these should only be placed in the setting of a flow-limiting dissection or other problem. Patency, adequacy of flow, and preservation of runoff are confirmed on completion angiography. An example is shown in Figure 1. A rapid rate of flow through the recanalized segment is believed to be a strong predictor of a successful subintimal angioplasty.
Other significant stenotic arterial lesions identified outside the area of subintimal angioplasty can be treated concurrently at the time of the procedure with adjunctive balloon angioplasty and/or stent placement. Patients are given clopidogrel for 4 weeks after the procedure, followed by aspirin indefinitely. We generally follow-up with these patients with routine office visits that include pulse examination and serial surveillance color duplex ultrasonographic evaluations at 3- to 6-month intervals.
During the last 2 years, 40 patients with critical ischemia and long SFA occlusions were treated with subintimal angioplasty. Patients who had stenosis as opposed to occlusion were not included. The median occlusion length was 8 cm. Technical success was achieved in 90% of patients. Reasons for failure of the procedure include inability to re-enter the patent lumen distally, inability to pass the wire for the entire length of the occlusion, and inability to perform angioplasty on the recanalized segment. Although perforation frequently results in procedural failure, it may not preclude performance of successful subintimal angioplasty at the same setting, as long as an alternative subintimal channel can be created. The technique allows for the treatment of long occlusions throughout the lower extremity. In our series, patency rates at 12 and 24 months for all patients on an intention-to-treat basis were 64% and 51%, respectively (Figure 2). For technically successful subintimal angioplasties, the corresponding patency rates were 74% and 59%, respectively. The patency rates for subintimal angioplasty are somewhat less than for bypass procedures, but it does offer an attractive, less-invasive option, especially for high-risk patients.
In the setting of a late failure, many patients will remain asymptomatic, especially when areas of gangrene or amputation sites have gone on to heal. Patients who ultimately require bypass surgery can almost always have a bypass that is no more distal than would have been performed prior to the subintimal angioplasty. It is important to keep preservation of bypass options in mind when performing subintimal angioplasty, as well as to avoid the creation of extensive dissection planes that extend well beyond the occlusion.
One technical modification we have utilized is the over-the-top 6F sheath with balloon stabilization of the guidewire for the performance of subintimal angioplasty. This permits the performance of complete diagnostic angiography and allows for subintimal angioplasty without a second puncture. In addition, any incidentally encountered aortoiliac pathology can be concurrently treated. This also helps to prevent the complications associated with the somewhat more difficult prograde puncture.
Several alternative approaches to subintimal angioplasty have been described. Retrograde subintimal recanalization performed through the popliteal artery is one such approach. A retrograde popliteal artery puncture is made under ultrasound guidance, and recanalization is performed in a distal to proximal direction.8,9 One-year patency rates of 62% have been reported for such subintimal recanalizations. Balas et al reported on ?open? subintimal angioplasty in cases in which there is a flush occlusion at the origin of the SFA.10 When a flush occlusion is present, it may be difficult to initiate the subintimal dissection plane. Additionally, the origin of the profunda femoral artery may be compromised either by the dissection or the subsequent balloon angioplasty.
This procedure involves a cutdown with exposure of the common, superficial, and deep femoral arteries. The SFA is opened, and a subintimal dissection plane is created under direct visualization. The dissection is then completed, and the native lumen is re-entered endoluminally under fluoroscopic guidance. After balloon angioplasty, a formal endarterectomy of the SFA is performed, and the proximal origin of the dissection plane is tacked open with sutures. The artery is closed with a patch. Such an approach may expand the applicability of the technique but does make any subsequent intervention more complex by virtue of the operative scarring. Until the long-term durability of this approach is determined, a primary bypass procedure may be preferable.
In our series, two patients underwent subintimal angioplasty after a failed bypass.7 Both procedures were performed for a threatened limb, were technically successful, and were patent at 8 and 26 months later. This is potentially one of the more attractive scenarios for the use of subintimal angioplasty in that it can avoid the technical difficulties associated with reoperative bypass surgery. However, Walker et al have previously reported on 12 patients who presented with failed infrainguinal bypasses and limb-threatening ischemia.11 These patients underwent an attempt at subintimal angioplasty of the occluded native vessels. Seven of the cases were technically successful, but at a mean follow-up of 4 weeks, only one of the previously occluded segments remained patent. The long-term success of subintimal angioplasty after a failed bypass remains to be seen.
Since the Leicester group’s initial report, the experience with subintimal angioplasty has expanded to centers around the world and to additional anatomic segments, including tibial and iliac vessels.
Subintimal angioplasty will likely continue to have a role in the treatment of lower-extremity ischemia, and its popularity is growing, especially in high-risk patients. It offers many advantages, including reduced anesthesia requirements, a minimally invasive approach, and potential reductions in length of stay and cost.
When applied judiciously, bypass options can be preserved. The availability of this technique should not, however, be used as justification to lower the threshold for the treatment of mild intermittent claudication. The ultimate utility and applicability of this technique will be determined by its long-term results.
Evan C. Lipsitz, MD, is Assistant Professor of Surgery at Montefiore Medical Center and the Albert Einstein College of Medicine Division of Vascular and Endovascular Surgery-Vascular Laboratory, in Bronx, New York. He holds no financial interest in any of the products or companies mentioned herein. Dr. Lipsitz may be reached at (718) 920-2016; Elipsitz@aol.com.
Takao Ohki, MD, is Chief of Vascular and Endovascular Surgery and Associate Professor of Surgery at Montefiore Medical Center and the Albert Einstein College of Medicine Division of Vascular and Endovascular Surgery-Vascular Laboratory, in Bronx, New York. He holds no financial interest in any of the products or companies mentioned herein. Dr. Ohki may be reached at (718) 920-2016; Takohki@msn.com.
Frank J. Veith, MD, is Professor of Surgery at Montefiore Medical Center and the Albert Einstein College of Medicine Division of Vascular and Endovascular Surgery-Vascular Laboratory, in Bronx, New York. He holds no financial interest in any of the products or companies mentioned herein. Dr. Veith may be reached at (718) 920-2016; email@example.com.
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