Transcatheter interventions for the treatment of peripheral atherosclerotic lesions: part I

Sirolimus-eluting versus bare stents for bailout after suboptimal infrapopliteal angioplasty for critical limb ischemia: 6-month angiographic results from a nonrandomized prospective single-center study

PURPOSE

To report the 6-month angiographic results from a prospective single-center study investigating the efficacy and outcome of sirolimus-eluting stents used for bailout after infrapopliteal revascularization of patients with critical limb ischemia (CLI).

METHODS

Twenty-nine patients (21 men; mean age 68.7 years) underwent infrapopliteal revascularization with bare metal stents (group B) implanted for bailout in 65 lesions (38 stenoses and 27 occlusions) in 40 infrapopliteal arteries. Another 29 patients (21 men; mean age 68.8 years) underwent infrapopliteal bailout stenting with sirolimus-eluting stents (group S) in 66 lesions (46 stenoses and 20 occlusions) in 41 vessels. Preliminary 6-month angiographic and clinical results were analyzed.

RESULTS

Hyperlipidemia and symptomatic cardiac and carotid diseases were more pronounced in group S (p<0.05). Technical success was 96.6% (28/29 limbs) in group B versus 100.0% in group S (p=0.16). Six-month primary patency was 68.1% in group B versus 92.0% in group S (p<0.002). Binary in-stent and in-segment restenosis rates were 55.3% and 66.0%, respectively, in patients with bare stents versus 4.0% and 32.0%, respectively, in patients treated with the sirolimus-eluting stents (both p<0.001). The target lesion re-intervention rate at 6 months was 17.0% in group B versus 4.0% in group S (p=0.02). Limb salvage was 100% in both groups. Six-month mortality and minor amputation rates were 6.9% and 17.2%, respectively, in group B versus 10.3% and 3.4%, respectively, in group S (p=0.32 and p=0.04, respectively).

CONCLUSIONS

Sirolimus-eluting stents seem to restrict neointimal hyperplasia in the infrapopliteal vascular bed.

The Clinical Application of Cryoplasty for Infrainguinal Peripheral Arterial Disease

Interventional outcomes for peripheral arterial disease of the lower extremity have long suffered from suboptimal patency rates. Many drugs and devices have been studied in an attempt to alter the aggressive neointimal response witnessed in infra-inguinal vessels with little success. Cryoplasty, a recent entrant into the endovascular arena, combines the time-tested mechanics of percutaneous transluminal angioplasty with the biologically favorable effects of cryotherapy. Cryoplasty specifically targets infra-inguinal lesions and minimizes neointimal proliferation via induction of apoptosis in the cell lines that contribute to restenosis. In addition, the mechanistic effects on the architecture of the vessel wall and the plaque itself have been found to reduce the likelihood of significant dissection following cryoplasty as compared with those expected with percutaneous transluminal angioplasty. Several clinical trials have demonstrated the efficacy of cryoplasty in patients with superficial femoral and popliteal arterial disease, as well as in critical limb ischemia patients with tibioperoneal arterial disease. Current clinical applications in the lower extremity will be reviewed along with technical tips for device use and opportunities for device synergy with other existing technologies.

Endovascular Excimer Laser Atherectomy Techniques to Treat Complex Peripheral Vascular Disease: An Orderly Process

Peripheral vascular disease represents the largest obstructive subsegment within the vascular system. Advances in equipment, techniques, biochemical treatments, and the influx of multiple specialties into this arena indicate a coming tidal wave of change to the standard treatment plan for patients with claudication and especially critical limb ischemia. Initial attempts in the 1980s to utilize the "laser" to treat peripheral vascular disease led to a clinical debacle: wavelengths and methods were not optimized; tissue heating was excessive, resulting in restenosis. Since then the "laser" has fallen from grace for endovascular treatment, although it has an infinite set of potential wavelengths, energy levels, and delivery methods. The xenon chloride, excimer laser, a pulsed 308-nm system, has overcome many of these early catastrophes. The long, ongoing success of this method of photoablating thrombus and plaque represents a true step forward in the endovascular treatment of occlusive disease. Although only a tool, the excimer laser provides a means to utilize electromagnetic energy instead of shearing mechanical force to resolve occlusions. With its active element at the tip, the excimer laser requires much less mechanical translation force to cross total occlusions, find the distal lumen, and thereby cause less plaque destabilization. In addition, removing the firm surface layer of plaque, decapping, and some of the plaque volume, debulking, exposes the softer subsegments of the plaque to balloon angioplasty. Utilizing this method, more complex lesions can be approached safely, with a high likelihood of successful revascularization and a low risk of potentially limb-threatening complication.

Cryoplasty for the Treatment of Femoropopliteal Arterial Disease: Results of a Prospective, Multicenter Registry

PURPOSE

Despite suboptimal results, angioplasty of femoropopliteal arterial lesions has been a mainstay of endovascular therapy for many years. The recent introduction of cryoplasty marks a potential advance in the ability to effectively treat peripheral arterial atherosclerotic stenoses. This article presents the results of a prospective, multicenter trial that evaluated the efficacy of cryoplasty for femoropopliteal disease.

MATERIALS AND METHODS

One hundred two patients with claudication and lesions of the superficial femoral and popliteal arteries of no greater than 10 cm were studied. All patients were treated with a primary strategy of stand-alone cryoplasty with use of the PolarCath cryoplasty system. The primary endpoints of the study were acute technical success and clinical patency at 9 months. Technical success was defined as the ability to achieve residual angiographic stenosis no greater than 30% and residual stenosis less than 50% by duplex ultrasound (US) imaging. Clinical patency was defined as freedom from target lesion revascularization within 9 months. Primary patency was defined by a duplex US systolic velocity ratio no greater than 2.0.

RESULTS

A total of 102 patients were enrolled at 16 centers. Of those treated, 31% had diabetes and 31% were active cigarette smokers. The majority of the lesions were confined to the superficial femoral artery (84.3%) and 14.7% presented with total occlusions. The mean vessel diameter treated was 5.5 mm +/- 0.5, the mean stenosis diameter was 87% +/- 10%, and the mean lesion length was 4.7 cm +/- 2.6. The technical success rate was 85.3% with a mean residual stenosis after cryoplasty of 11.2% +/- 11.2% (P < .05 vs baseline). Clinical patency in this group was 82.2%, as only 16 patients required target lesion revascularization during the 9-month surveillance period. Primary patency determined by duplex US was 70.1%.

CONCLUSIONS

Cryoplasty demonstrated a high degree of acute angiographic success and a low frequency of target lesion revascularization. The patency rate observed compares favorably to that previously documented with conventional angioplasty.

Percutaneous laser-assisted recanalization of long chronic iliac artery occlusions: primary and mid-term results

We report the primary and mid-term outcome of patients with long chronic iliac artery occlusions after percutaneous excimer-laser-assisted interventional recanalization. Between 2000 and 2001, 43 patients with 46 chronic occlusions of either the common iliac artery (n=27), the external iliac artery ( n=13) or both (n=3) underwent laser-assisted percutaneous transluminal angioplasty and implantation of stents. The average length of the occlusion was 57.1+/-26 mm. After laser-assisted angioplasty and implantation of a total of 60 stents, the patients were followed up for up to 4 years. Patency rates were analyzed by ankle-brachial index (ABI) measurement and duplex ultrasound. The primary technical success rate was 95.3%, with a major complication rate of 6.9%. Clinical improvement as categorized by the Rutherford guidelines could be observed in 97.6% of cases. The ABI of all patients improved from an average of 0.46+/-0.08 before intervention to 0.97+/-0.13 at the end of the follow-up period. The overall primary patency rate was 86.1%. Four reinterventions were successful (secondary patency rate 95.4%). The mid-term results of the percutaneous recanalization of iliac artery occlusions with primary and secondary patency rates of 86.1 and 95.4% are similar to those of the treatment of short stenoses.

Lower extremity arterial occlusive disease: Role of percutaneous revascularization

Percutaneous endovascular interventions for peripheral arterial disease are indicated in carefully selected patients with favorable anatomy and associated clinical symptoms. Although endovascular therapy appears to be hemodynamically equivalent to other modalities in isolated iliac disease, this does not appear to be the case for infrainguinal disease, particularly when the disease is diffuse and extensive. Such disease in these beds can often be treated surgically, although there is an increasing role for percutaneous therapies, particularly in patients at higher surgical risk. Catheter-based therapy should be considered an integral part of comprehensive medical therapy in patients with lower extremity peripheral arterial disease. Embarking on an endovascular approach to therapy should involve a frank physician-patient discussion of the risks, benefits, and durability of the proposed procedure tailored to anatomic locale and patient-specific factors.

Endovascular placement of an extraluminal femoropopliteal bypass graft in human cadavers

PURPOSE

A method to create an extraluminal femoropopliteal bypass graft using endovascular techniques was evaluated in situ on cadaver extremities in an attempt to develop a minimally invasive alternative technique for the management of infrainguinal occlusive arterial disease.

METHODS

The endovascular placement of an extraluminal femoropopliteal bypass graft was undertaken in 5 cadaver legs. Following percutaneous access to the popliteal artery (PA) or common femoral artery (CFA), a Rosch-Uchida needle was used to perforate the vascular wall, followed by the creation of an extraluminal tract using a looped wire and catheter. Once the desired level was reached the needle was again used to perforate the vascular wall of the proximal superficial femoral artery (SFA) or PA depending on the access used. Self-expanding expanded polytetrafluoroethylene (ePTFE) stent-grafts were then deployed to establish the extraluminal femoropopliteal bypass connecting the two arterial puncture sites. Following dilatation of the stent-graft, angiography was performed to assess the endoprostheses and to look for contrast leaks.

RESULTS

Technical success was achieved in all 5 legs. Procedure time varied from 15 to 30 min. The angiographic studies performed immediately after completion of the bypass procedure showed patency of the grafts with no evidence of kinking or leakage in any of the cases.

CONCLUSION

This study has proved that the endovascular placement of an extraluminal femoropopliteal bypass graft in human cadaver legs using endovascular techniques under fluoroscopic control is technically feasible.

Endovascular treatment of the subclavian artery: Stent implantation with or without predilatation

The endovascular treatment of subclavian artery (SA) lesions is less invasive than open surgical repair, with a low rate of complications. We report our experience in 89 subclavian obstructive lesions (n = 86) treated with stenting: 76 (85.3%) stenoses and 13 (14.6%) total occlusions. The left side was most frequently involved (83.1%), localized at the prevertebral segment in 91%. Technical success was obtained in 83 (93.3%) cases, 100% in stenotic lesions and 53.8% in total occlusions. There were nine global complications (10.1%): five (5.6%) at site of puncture, two distal embolization (2.2%), and two (2.3%) major events. The long-term follow-up was 3.51 +/- 1.98 years, during which time 13 (16.8%) restenoses and 2 (2.6%) reocclusions were noted. Subgroup analysis of patients with stenting after predilatation versus direct stenting technique showed in-hospital complications only in the first group, with a restenosis rate of 28.5% vs. 4.7%, respectively (P = 0.003). We consider stenting for SA obstructive lesions the first therapeutic option.

Subintimal angioplasty for infrainguinal occlusive disease

Subintimal angioplasty is a relatively new endovascular approach for the treatment of patients with femoropoliteal or tibial artery occlusion. The procedure involves intentionally creating a false channel or dissection around an arterial occlusion, then reentering the true lumen distally. The procedure has a relatively low incidence of complications and a high rate of technical success.Short-term patency has been fair in some reports and poor in others. Long-term results are not available. Aspirin and possibly anticoagulation or antiplatelet agents may improve technical success and short-term patency. Further studies with longer follow-up are required before it can be recommended as a potentially viable alternative to arterial bypass.

Angioplasty/stenting of the superior mesenteric artery and celiac trunk: early and late outcomes

PURPOSE

To analyze the early results and durability of angioplasty/stenting of the superior mesenteric artery (SMA) and celiac trunk (CT).

METHODS

Twenty-two patients (19 women; mean age 69.2 years, range 52-88) with 24 symptomatic SMA or CT stenotic lesions were treated with dilation/stenting over a recent 4.5-year period. Two patients had lesions in both the SMA and CT treated. Clinical follow-up and duplex exams were done to evaluate long-term patency. Kaplan-Meier life-table analyses estimated the freedom from recurrent stenosis and recurrent symptoms, as well as survival rates.

RESULTS

The initial technical and clinical success rates were 96% (23/24) and 95% (21/22), respectively, with no perioperative mortality or major morbidity. During a mean follow-up of 26 months (range 1-54), the primary late clinical success rate was 61% (11/18; 4 lost to follow-up), and freedom from recurrent stenosis (> or =70%) was 30% (6/20). The freedom from recurrent stenosis at 1, 2, 3, and 4 years were 65%, 47%, 39%, and 13%; freedom from recurrent symptoms was 67% at all 4 intervals. The survival rates were 93%, 93%, 80%, and 53% at 1 to 4 years, respectively.

CONCLUSIONS

Angioplasty/stenting of SMA and CT stenoses has a high initial technical success rate and acceptable early and late clinical outcomes; however, it is associated with a high incidence of late restenosis based on strict Doppler criteria.

Infrapopliteal angioplasty

Endovascular therapy for infrapopliteal vascular disease is gaining acceptance as there is growing evidence demonstrating its safety and effectiveness. It is most commonly used to treat patients with chronic critical limb ischemia (CLI) for limb salvage and wound healing. Its use to treat lifestyle altering claudication remains controversial. For the treatment of CLI, limb salvage rates with infrapopliteal percutaneous transluminal angioplasty (PTA) are high enough that these techniques are offering an alternative to bypass surgery. Current patency rates from infrapopliteal PTA can be improved further by proper patient selection, ensuring straight-line flow to the foot in at least one tibial vessel, and close patient surveillance for early reintervention. Possible future advances including the use of drug-eluting stents, cutting balloons, and aggressive antiplatelet regimens are being tested to improve clinical outcomes following endovascular interventions on the tibial arteries.

Transradial approach for percutaneous transluminal angioplasty and stenting in the treatment of chronic mesenteric ischemia

Chronic mesenteric ischemia (CMI) occurs in the presence of slowly progressive, long-standing stenoses of the visceral arteries secondary to atherosclerosis. Angioplasty and stenting are emerging as therapeutic alternatives to surgery in treating CMI. The transradial approach is an attractive alternative access for performing stenting in CMI at improved safety and ease. A case of CMI treated with stenting of the visceral arteries by both transradial and femoral approaches is presented here. The main difficulty in accessing the celiac and mesenteric arteries through the femoral approach is the angle between the aorta and these vessels, which often leads the operator to use multiple catheters. The main advantage of the radial approach (as well as the brachial one) is that it allows easy coaxial alignment of the catheter with the artery. The main problem is the inadequate length of the currently available catheters. The radial approach eliminates the risk for vascular complications and permits early ambulation.

Novel growth stent for the permanent treatment of vessel stenosis in growing children: An experimental study

Stent implantation in stenotic vessels of infants and small children is problematic because there is no ideal stent model that is small enough to be easily introduced into the infant femoral vein or artery and, at the same time, large enough to be dilated during growth to adult vessel diameters. To overcome this problem, we designed a new stent, the growth stent. This growth stent is a balloon-expandable metal stent. Two longitudinal halves are connected with bioabsorbable sutures so that a circular stent is created. It was postulated that after absorption of the sutures the stent would not impede growth. Twenty of these stents were implanted in the aorta, pulmonary arteries, and inferior vena cava of piglets (average weight 6.9 kg). After 18 weeks (14-23 weeks) and a mean weight gain of 59 kg, none of the stented vessels showed any significant stenosis or pressure gradient, documented by angiography and catheter pullback. During fluoroscopy, the two halves of the stent were clearly separated in all animals. The growth stent has the potential to be nonrestrictive during vessel growth, and thus is a promising new device for the permanent treatment of stenotic vessels in infancy and childhood.

Endovascular treatment of celiac and mesenteric arteries stenoses: Applications and results

PURPOSE

To evaluate the safety and assess the role of endovascular therapy in a variety of conditions related to celiac and mesenteric vascular occlusive disease. Patients and methods Our retrospective study population included 25 consecutive patients (mean age, 66 years), in whom 28 procedures were performed on 26 stenosed or occluded mesenteric vessels (superior mesenteric artery [SMA] or celiac artery [CA]). Indications included chronic mesenteric ischemia (21 patients), including 2 patients who underwent stenting prior to a planned operative repair of a juxtamesenteric AAA. Three liver transplantation patients underwent stenting of an associated CA stenosis. One patient with a splenorenal bypass underwent stenting on an associated CA stenosis. The technical and clinical success rates and the incidence of complications were determined. Follow-up parameters included maintained patency on duplex sonography and sustained clinical benefit. The need for additional interventions was noted.

RESULTS

All procedures but one were technically successful (96%). Major complications occurred in three patients (one transient contrast-induced nephrotoxicity and two pseudoaneurysms). Immediate clinical success was achieved in 22 patients (88%). The three clinical failures included two patients with an excellent angiographic outcome, but with single-vessel moderate severity disease. Survival table analysis of delayed clinical outcome showed primary and primary-assisted clinical benefits at 11 months of 85% and 91%, respectively. Primary and primary-assisted stent patencies, as assessed by duplex sonography and/or angiography, at 6 months were both 92%. Angiographically documented restenosis occurred in three patients. Restenosis in two patients with CA stents was due to extrinsic compression, and it was without symptoms in one patient and was treated satisfactorily by restenting in the other patient. Restenosis in one patient with an SMA stent was successfully treated by restenting.

CONCLUSIONS

Our experience suggests a potential role for endovascular therapy of celiac and mesenteric arterial occlusive disease in a variety of clinical scenarios, with a low incidence of complications and a high technical success rate.

Guidelines for the Reporting of Renal Artery Revascularization in Clinical Trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

Current status of intravascular stents as delivery devices to prevent restenosis

The acute technical success of percutaneous transluminal angioplasty (PTA) has been improved with the use of intravascular stents. However, stent placement has led to the development of an increased myointimal hyperplastic response leading to late reduction in vessel lumen. Restenosis (> or =50% reduction in reference lumen diameter) rates for coronary angioplasty and stenting are reported between 20% and 50% at 1 year. Several studies are currently evaluating novel delivery of antiproliferative agents to prevent neointimal hyperplasia. The authors review the mechanism of neointimal hyperplasia as it relates to stent placement and discuss recent and ongoing trials evaluating intravascular brachytherapy and drug-eluting stent technology in the inhibition of restenotic lesions.

Long-term outcome of patients with claudication after balloon angioplasty of the femoropopliteal arteries

PURPOSE

To report the long-term outcome of patients with lifestyle-limiting claudication after percutaneous transluminal angioplasty (PTA) of the femoropopliteal arteries.

MATERIALS AND METHODS

Between 1989 and 1992, 173 consecutive claudicant patients (mean age, 65 years; age range, 41-90 years) underwent PTA in 218 limbs; all interventions included femoral and/or popliteal arterial segments, and additional iliac (n = 27) and infrapopliteal (n = 11) arterial lesions were also treated. Patients were followed up for 7-10 years. Altogether, 37 (17%) limbs were classified as Fontaine class 2A, and 181 (83%) were class 2B. Average length of the primary lesion was 5.2 cm. Reinterventions were analyzed. Patency rates and patient survival were assessed by means of life table analysis. Cox-Mantel tests and Cox proportional hazards models were used to define associated independent determinants. Development of chronic critical ischemia (CCI) and its determinants was assessed by using the Pearson chi(2) test and multiple logistic regression analysis.

RESULTS

The primary and secondary patencies (+/- standard error of the estimate), respectively, were 46% +/- 3 and 63% +/- 3 at 1 year, 25% +/- 3 and 41% +/- 4 at 5 years, and 14% +/- 3 and 22% +/- 4 at 10 years. One-third (71 of 218) of the limbs required repeat interventions, including surgical revascularization in 35 limbs. Fourteen (6.4%) limbs developed CCI, resulting in a 0.8% incidence per year. In multivariate analysis, poor postinterventional peripheral runoff was an indicator of increased risk of CCI development (P =.03).

CONCLUSION

Although the long-term patency rates of PTA of the femoropopliteal arteries in claudicant patients were poor, the acceptable number of reinterventions and the low frequency of development of CCI imply the long-term benefits achievable with this treatment.

Recent advances in peripheral angioplasty and stenting

Utilization of percutaneous interventions for arterial and venous occlusive lesions continue to increase. With the progression of the technology supporting these therapeutic measures, the results of these interventions may be expected to improve. In general, a comparison of techniques for revascularization demonstrates similar initial technical success rates for surgery and percutaneous transluminal angioplasty. Angioplasty is often associated with lower procedural morbidity and mortality rates. Conversely, surgery frequently provides greater long-term patency. Late failure of percutaneous therapies may often be treated successfully with reintervention, however. The continued accumulation of experience with PTA and stenting will ultimately define its role in the management of occlusive disease.

Guidelines for the reporting of renal artery revascularization in clinical trials

Although the treatment of atherosclerotic renal artery stenosis with use of percutaneous angioplasty, stent placement, and surgical revascularization has gained widespread use, there exist few prospective randomized controlled trials (RCTs) comparing these techniques to each other or against the standard of medical management alone. To facilitate this process as well as help answer many important questions regarding the appropriate application of renal revascularization, well-designed and rigorously conducted trials are needed. These trials must have clearly defined goals and must be sufficiently sized and performed so as to withstand intensive outcomes assessment. Toward this end, this document provides guidelines and definitions for the design, conduct, evaluation, and reporting of renal artery revascularization RCTs. In addition, areas of critically necessary renal artery revascularization investigation are identified. It is hoped that this information will be valuable to the investigator wishing to conduct research in this important area.

Transcatheter interventions for the treatment of peripheral atherosclerotic lesions: part II

Transcatheter endovascular procedures are increasingly used to treat symptomatic peripheral atherosclerosis. This second part of a two-part review assesses the existing supportive evidence for the application of recently introduced transcatheter treatments for lesions that cause cerebrovascular ischemia and stroke. Studies were identified via MEDLINE (January 1993 through April 1999) and reference lists of identified articles. When multicenter prospective randomized trials or other high-quality studies were unavailable, studies with at least 50 patients per treated group and a minimum follow-up duration of 6 months were included. For each application, the authors assessed the quality of evidence (efficacy, safety, and, where available, cost-effectiveness) and made recommendations with appropriate caveats. Although recommendations based on proven efficacy and cost-effectiveness cannot be made in general, the use of transcatheter therapies can be supported in specific circumstances based on expected reduction in procedure-related morbidity and/or mortality. It is hoped that the identification of deficiencies in the literature will inform and inspire critically needed research in this area.