Re-Entry Devices in the Treatment of Peripheral Chronic Occlusions

Abstract

Chronic occlusions are present in up to 40% of patients who undergo treatment for symptomatic peripheral arterial disease. The primary difficulty encountered during the treatment of chronic occlusions is inability to re-enter the true lumen after subintimal crossing of the occlusion. Two devices have been designed to mitigate this limitation via controlled re-entry. Herein, we report our experience with the Outback LTD catheter and the Pioneer Plus Catheter PPlus 120 in re-entering the true arterial lumen during percutaneous intentional extraluminal revascularization for peripheral chronic occlusions involving the superficial femoral artery. In reviewing our peripheral interventions performed from February 2006 through February 2009, we evaluated angiograms, patients' characteristics, presentations, types of lesions, procedural successes, complications, and symptom-free intervals. The total study population consisted of 23 patients. The Outback catheter was used in 15 patients and the Pioneer catheter in 8 patients.

The procedure was successful in all 8 Pioneer cases (100%) and in 13 of the 15 Outback cases (87%). All 8 (100%) of the patients in the Pioneer group and 12 of the 14 patients in the Outback group (86%) remained asymptomatic at an average of 12 months. Overall, there were no procedural complications, amputations, or deaths. This single-center experience demonstrates that the Outback and Pioneer re-entry catheters are safe and effective in managing peripheral chronic occlusions, with an average symptom-free interval of 12 months. This management strategy proves to be reasonable when standard techniques fail to achieve true lumen re-entry.

A chronic occlusion can be defined as a lesion that has been present for greater than 3 months and exhibits Thrombolysis in Myocardial Infarction (TIMI) flow grade 0 or 1.^1,2 Chronic occlusions are present in up to 40% of patients who undergo treatment for symptomatic peripheral arterial occlusive disease¹ and have been cited as one of the primary reasons for procedural failures. Subintimal recanalization, or percutaneous intentional extraluminal recanalization (PIER), has been described as a reasonable treatment for peripheral chronic occlusions. Re-entry of the true arterial lumen can be achieved either with a conventional guidewire or, if needed, with a re-entry catheter. Subintimal angioplasty during percutaneous intervention for femoropopliteal occlusions was first described by Bolia and colleagues in 1990.³ Since then, this technique's success has caused its use to be extended to treatment of stenotic and occlusive lesions in the iliac and popliteal arteries, in trifurcations (infra-popliteal arteries), and in crural vessels, where it has had an important role in the management of critical limb ischemia. The potential advantage of this method is that thrombogenic atheroma is “isolated” during subintimal intervention. Moreover, the false lumen (which is created by this technique) is free from both endothelium and atheroma; this might improve long-term results, since re-stenosis is frequently the result of neointimal hyperplasia or atheroma formation.

The primary limitation to successful treatment of chronic occlusions is reported to be failure to re-enter the true lumen after subintimal crossing of the occlusion.^4–6 With the sole use of a guidewire, true lumen re-access has been estimated to be unsuccessful in approximately 20% of cases.⁷ Several factors—such as operator skill, lesion length, degree of calcification, and patency of runoff vessels—influence these success rates. In an effort to overcome the limitations in the traditional methods of re-entering the true arterial lumen, 2 catheters have been designed to improve re-entry after crossing a peripheral chronic occlusion. These devices are the Outback® LTD® Re-Entry Catheter (Cordis, a Johnson & Johnson company; Bridgewater, NJ) and the Pioneer Plus Catheter PPlus 120 (subjected to Class 2 recall^* in January 2011 by Medtronic CardioVascular; Santa Rosa, Calif).

We conducted a retrospective study of patients who had been treated with the Outback or Pioneer re-entry catheters for the management of chronic occlusions that involved the superficial femoral artery (SFA). Our aim was to determine the procedural success rate and the symptom-free interval at clinical follow-up in these patients.

Patients and Materials

From February 2006 through February 2009, patients who underwent peripheral intervention of the SFA with use of a re-entry catheter were identified by prospectively logged analysis. The total study population consisted of 23 patients. The Outback catheter was used in 15 patients and the Pioneer catheter in 8 patients. All patients had experienced unsuccessful attempts to re-enter the true arterial lumen with a variety of other catheters and wires (hydrophilic wires, J-shaped hydrophilic wires, and Quick-Cross® catheters), before the attempt was made with a true-lumen re-entry device. We reviewed the final angiograms to determine procedural success. The patients' charts were reviewed, and some of the data that were collected included age, sex, history of tobacco use, coronary artery disease, previous interventions for peripheral arterial disease, type of clinical presentation (on the basis of the Rutherford classification for peripheral arterial disease⁸), type of lesion (on the basis of the TransAtlantic Inter-Society Consensus [TASC] II classification⁸), and other atherosclerotic risk factors, such as diabetes mellitus, hypertension, and dyslipidemia (Table I). The patients were divided into 2 cohorts, in accordance with the re-entry catheter that was used. The patients were followed clinically for an average of 1 year. The mean ages of the patients in the Outback and Pioneer groups were 69 and 59 years, respectively. The Pioneer group had a higher percentage of patients with diabetes, and the Outback group had higher percentage of patients with dyslipidemia and with symptoms that were severe on the basis of the Rutherford classification. Most lesions in the Outback group were categorized as TASC types C and D, and most in the Pioneer group were TASC types B and D. Patients with TASC types C and D lesions were offered bypass surgery as an alternative treatment.

TABLE I. Characteristics of the 23 Patients

The Pioneer catheter (Fig. 1) is a 6F catheter with 2 wire ports, each 0.014-inch compatible. One port houses a hollow-core nitinol needle that is guided by an integrated 64-element, phased-array intravascular ultrasound (IVUS) device and is connected to a Volcano s5i™ Imaging System console (Volcano Corporation; Rancho Cordova, Calif), which enables vessel imaging. The re-entry device is delivered through the subintimal plane and is placed with the distal tip at the level of the SFA re-entry site. By slowly rotating the catheter, the operator maneuvers the nitinol needle until its tip is oriented toward the true lumen and is lined up at the 12-o'clock position on the ultrasonographic image. Finally, the needle is plunged into the true lumen at a controlled depth.⁹

Fig. 1 Pioneer catheter with needle deployed. (Photo courtesy of Medtronic, Inc.; Minneapolis, Minn.)

The Outback LTD catheter (Fig. 2) is a 6F-compatible catheter with a hollow 22G needle for distal vessel entry with the aid of fluoroscopic imaging. The device is delivered to the distal subintimal space adjacent to the reconstitution of the vessel, and 2 orthogonal angiographic views are taken. The proprietary “locate, tune, and deploy” technique is used to increase the success of distal re-entry. An L-shaped fluoroscopic marker provides reproducible orientation of the tip toward the re-entry target site. To fine-tune positioning at the target re-entry site, the “T”une fluoroscopic marker, combined with a 90° orthogonal view, confirms the desired alignment. Last, the 22G nitinol re-entry cannula is plunged into the distal vessel to re-enter the true lumen.¹⁰ The Outback system is then retrieved, and dilation and optional stenting or atherectomy procedures can be accomplished (Figs. 3, 4 and 5).

Fig. 2 Outback catheter with needle deployed. (Photo courtesy of Cordis, a Johnson & Johnson company; Bridgewater, NJ.)

Fig. 3 Outback system: L marker (arrow) orients the catheter toward the true lumen of the right superficial femoral artery.

Fig. 4 Outback system: the re-entry needle is deployed (arrow), and the guidewire is advanced into the true lumen.

Fig. 5 Outback system: restoration of excellent blood flow in the right superficial femoral artery after re-entry and stenting (arrow).

Results

Continuous data are presented as means. Categorical data are given as counts (percentages). Overall, successful re-entry was achieved in all 8 of the Pioneer cases (100%) and in 13 of the 15 Outback cases (87%). The average lesion length was 18.5 cm in the Outback group and 24.8 cm in the Pioneer group.

In the 21 successful cases from both groups, the average distance between the distal cap of the chronic occlusion and the site of re-entry was 2.0 cm. The average time for re-entry—defined as time from introduction of the re-entry catheter through the access sheath to the time the wire re-enters the true arterial lumen—was 8.4 min in the Outback group and 8.5 min in the Pioneer group. Subsequent therapy in all successfully treated patients included balloon angioplasty with stent placement. The procedural characteristics are listed in Table II.

TABLE II. Procedural Characteristics of the Superficial Femoral Artery Lesions

There were no early or late complications, such as perforation, dissection, or pseudoaneurysm. In 2 cases, the Outback was unsuccessful in re-entering the true lumen, despite multiple attempts. In one of these cases, the Outback was unsuccessful in re-entering the true lumen, due to side-branch prevention of its delivery past the chronic occlusion. In fact, the device was not tracking the subintima, but was following a side branch. In the other unsuccessful case, the patient had a previous aortofemoral bypass graft, and the acute angle of the aortic bifurcation restricted the operator's ability to advance the re-entry catheter.

Clinical follow-up was obtained in 22 of 23 patients in our study; 1 patient treated with the Outback was lost to follow-up. The average time of follow-up was 12 months. One hundred percent of the patients in the Pioneer group and 86% of the patients (12 of 14) in the Outback group remained asymptomatic at an average of 12 months. Two of the 22 patients reported no improvement in their symptoms.

Discussion

Previously, the treatment of peripheral chronic occlusions required manipulation with a hydrophilic guidewire and a low-profile support catheter to re-enter the true lumen. The primary limitation of this method was failure to re-enter the true lumen with the conventional guidewire after subintimal crossing of the occlusion. Propagation of the dissection beyond the end of the occlusion can result in re-entry of the wire at a distance well beyond the end of the occlusion. This inadvertent lengthening of the lesion can result in an unplanned increase in angioplasty and stenting. Furthermore, a dissection can affect branch points or collateral vessels in areas that are not involved in the occlusion, leading to a loss of surgical options and collateral vessels. One study reported that up to 47% of the collateral vessels distal to subintimally treated chronic occlusions of the lower extremity are lost after angioplasty, as are 27% of the collateral vessels proximal to the treated lesions.¹¹ Both the Outback and Pioneer catheters were designed to enable safe and controlled re-entry into the true arterial lumen.

The cost of each Outback LTD is approximately $1,800. The cost of each Pioneer catheter is $3,100, and it requires an IVUS machine.⁷ Therefore, cost and the availability of the IVUS platform will often be the determining factors in the choice of devices. In patients who present with chronic occlusion of a stent lumen, the Pioneer with IVUS guidance may (after full investigation) be a reasonable choice, because IVUS ensures direct visualization of the catheter passage through the occluded stent and not behind it. Both devices can inject small amounts of contrast agent from the side needle, in order to check positioning before advancing the guidewire. However, it must be noted that contrast injection can obscure visualization for re-entry and can even expand the width of the subintimal tract, thereby compressing the true arterial lumen and making re-entry difficult. The learning curve for the use of both devices is fairly reasonable: operators who have substantial experience with peripheral chronic occlusions need use the device only a few times to gain proficiency. Those without IVUS expertise might take longer to master the Pioneer catheter, because the Pioneer involves the use of IVUS.

Access via the contralateral common femoral artery is the most widely described approach for re-entry catheters. The ipsilateral antegrade common femoral artery approach can be used, but in some cases (primarily those involving a very small stump of the proximal SFA) it does not enable adequate guidewire and catheter manipulation. It is recommended that at least a 5-mm stump be present at the origin of the SFA for ipsilateral antegrade femoral access. In any event, for SFA occlusions in which the stump is shorter than 11 cm (the length of most femoral sheaths), entry is commonly achieved either from the contralateral common femoral artery approach or (if that is not feasible) from the transpopliteal approach. Some authors have advocated the use of the brachial approach to treat peripheral lesions, but the shaft length of many current interventional devices prohibits this approach if the distance from the left or right brachial artery to the reconstitution of the SFA exceeds 120 cm.

The 1st-generation model of the Outback catheter had a success rate of 80%.¹⁰ A more recent study with the later-generation Outback—which involved, primarily, patients with Rutherford category 5 ischemia—reported a 96% procedural success rate in achieving revascularization, with a 2% periprocedural complication rate.¹² The Pioneer catheter reportedly had a 95% procedural success rate with only 1 complication, in a recent retrospective study of patients who primarily had TASC C or D lesions.¹³

In our single-center experience, we noted that successful recanalization occurred in most lesions. A point of interest in another study¹² was its finding that lesion lengths were longer in successful procedures, which suggests that lesion length might not be a determinant of success when using a re-entry device. All of our patients underwent balloon angioplasty with stenting. Achieving optimal results with simple balloon angioplasty in long chronic occlusions that involve the SFA is difficult. A study of both the Outback and Pioneer re-entry catheters reported successful stenting of 100% of the lesions and a 100% patency rate at approximately 6 months.⁷

Limitations of our study include the retrospective nature of the data analysis. Postprocedural ankle-brachial indices or duplex studies were not available on all the patients, so vessel patency data on the basis of these tests were not collected. There were no deaths in our patient population, and none of our patients required minor or major amputations. Overall, at 1-year clinical follow-up, 91% of the patients remained symptom-free after treatment with a re-entry catheter for a chronic occlusion that involved the SFA.

Conclusion

Use of either the Outback or Pioneer re-entry catheter is a reasonable alternative to PIER in the management of peripheral chronic occlusions that involve the SFA. True-lumen re-entry catheters are effective in gaining wire passage back to the true arterial lumen and in facilitating successful endovascular treatment of chronic occlusions that would otherwise require surgical bypass. Long-term patency remains unknown, and randomized controlled trials that directly compare the 2 re-entry catheters in the management of peripheral chronic occlusions have yet to be designed.