CryoPlasty Therapy of the Superficial Femoral and Popliteal Arteries: A Single Center Experience

Endovascular techniques in limb salvage: cutting, cryo, brachy, and drug-eluting balloons

The complex pathophysiology response to injury of the lower-extremity arteries has prompted the development of several unique balloon technologies to overcome initial technical failures and short-term intimal hyperplasia. Cryoplasty alters the cellular and mechanical properties of the vessel wall during angioplasty. Cutting balloons incise the wall, preventing elastic recoil and allowing expansion of the lumen at a lower pressure, thus limiting barotrauma. Drug-eluting balloons actively transfer inhibitory compounds to the wall during the initial therapy, while brachytherapy balloons allow for localized delivery of radiation to inhibit the proliferative response seen after angioplasty. These platforms provide unique means to enhance immediate and short-term results and also reduce stent usage in the lower extremity.

Cryoplasty for peripheral arterial disease

BACKGROUND

Percutaneous balloon angioplasty is an endovascular technique for restoring blood flow through an artery that has become narrowed or blocked by atherosclerosis. Narrowing of the artery following angioplasty (restenosis) is the major cause of long-term failure. Cryoplasty offers a different approach to improving long-term angioplasty results. It combines the dilation force of balloon angioplasty with cooling of the vessel wall. This systematic review evaluated cryoplasty in peripheral arterial disease and provides focus for further research in the field. This is an update of a review first published in 2007.

OBJECTIVES

To assess the efficacy of, and complications associated with, cryoplasty for maintaining patency in the iliac, femoropopliteal and crural arteries in the short and medium term.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2012) and CENTRAL (2012, Issue 10). Trial databases were searched for ongoing or unpublished studies. We also searched the reference lists of relevant articles.

SELECTION CRITERIA

All randomised controlled trials in which participants with peripheral arterial disease (PAD) of the lower limbs, or lower limb bypass graft stenoses, were randomised to cryoplasty with or without another procedure versus a procedure without cryoplasty were considered. This included trials where all participants received angioplasty and the randomisation was for cryoplasty versus no cryoplasty and trials where cryoplasty was used as an adjunct to conventional treatment (for example stenting) against a control.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed, assessed and selected trials, extracted data and assessed risk of bias.

MAIN RESULTS

Seven trials (six primary cryoplasty and one adjunctive cryoplasty trial) with a combined total of 478 patients were included in this review. The trials reported patency and restenosis either by participant, lesion or vessel location. Follow-up ranged from 30 days to three years.Target lesion patency measured at various time points in two primary cryoplasty trials showed no statistically significant difference between the treatment groups. The adjunctive cryoplasty study showed that cryoplasty was associated with improved patency only at six months (OR 5.37, 95% CI 1.09 to 26.49, n = 90).Restenosis measured per patient (two primary cryoplasty trials) showed no statistically significant difference between the treatments. Restenosis measured by lesion (two primary cryoplasty trials) showed a statistically significant difference only within 24 hours of the procedure (OR 0.08, 95% CI 0.04 to 0.18, n = 192) favouring cryoplasty.Need for re-intervention was not significantly different in primary cryoplasty trial participants (per participant: OR 0.27, 95% CI 0.05 to 1.52, n = 241, I(2) = 89%; per lesion: OR 0.59, 95% CI 0.06 to 5.69, n = 307, I(2) = 94%). The adjunctive cryoplasty trial did not report on need for intervention.Immediate success of procedure (within 24 hours) was not significantly different in primary cryoplasty trial participants (per participant: OR 1.63, 95% CI 0.14 to 19.55, n = 340, I(2) = 95%; per lesion: OR 1.81, 95% CI 0.19 to 17.36, n = 397, I(2) = 90%). The adjunctive cryoplasty trial reported 100% success.Limb loss, deaths from all causes and the risk of complications immediately after treatment showed no statistically significant differences between the treatments.

AUTHORS' CONCLUSIONS

The benefit of cryoplasty over conventional angioplasty cannot be established as the number of randomised controlled trials is small and their quality is not sufficiently high. The technical success and primary patency rates seen in these trials are inconsistent and do not necessarily suggest a future role for cryoplasty in the treatment of PAD, but they cannot be reliably interpreted. Currently there are insufficient data to support the routine use of cryoplasty over conventional balloon angioplasty in the treatment of PAD.

Current Status of Drug-Eluting Stents and Drug-Eluting Balloons for the Superficial Femoral Artery

The endovascular management of symptomatic atherosclerotic superficial femoral artery disease is challenging and requires consideration of unique anatomic, hemodynamic, and biomechanical factors. For innovative local drug delivery technologies to have a cost-effective and clinically meaningful benefit, they must provide patency rates in more complex lesions equivalent or superior to those currently approved devices are able to provide. Several proof-of-concept trials have either been published or been recently presented and many more are in the pipeline suggesting biologic effectiveness of these hybrid devices in reducing restenosis. Local drug delivery technology has already been commercially introduced in some countries for a variety of clinical settings. However, although these technologies offer promise in improving outcomes following lower extremity intervention, caution and safety are paramount. Adequately powered, multicenter, well-designed, randomized controlled trials with long-term follow-up (3-5 years) are still needed to accurately assess safety and efficacy.

Cryoplasty offers no advantage over standard balloon angioplasty for the treatment of in-stent stenosis

In-stent restenosis is the primary failure mode of endovascular treatment of occlusive disease in the femeropopliteal segment. Cryoplasty has been proposed to reduce intimal hyperplasia through induction of apoptosis. We sought to evaluate the efficacy of cryoplasty for treatment of in-stent restenosis compared to conventional balloon angioplasty (CBA). After IRB approval, a retrospective record review was performed of reinterventions for in-stent restenosis by a single vascular surgery group at a university hospital. Reinterventions involving cryoplasty and CBA were evaluated at 1, 3, 6 and 12 months after intervention with duplex imaging to identify significant recurrent stenosis utilizing established velocity criteria. Data collected included basic demographic information and comorbidities as well as time to restenosis. Statistical analysis was performed using Kaplan–Meier survival curves with the log rank test, Wilcoxon rank test, and Cox proportional hazards models. From December 2004 to November 2007, 76 reinterventions were performed using CBA (n = 39) or cryoplasty (n = 37) for in-stent restenosis without placement of additional stents. Periprocedural technical success (>30% residual stenosis) was 100% for both groups, with no complications. The two cohorts were statistically similar in mean age, gender, comorbidities, tobacco use and use of statins, aspirin and Plavix. However, the mean lesion length was significantly longer in the cryoplasty cohort (CBA: 140.9 mm, Cyro: 191.7 mm; P = 0.032). The mean time to recurrent stenosis or need for additional secondary intervention was significantly shorter for the cyroplasty cohort than for the CBA, 4.09 and 10.79 months, respectively ( P = .0001). Recurrent stenosis-free survival was significantly lower in the cyroplasty cohort at 3 months (CBA: 96.9%, Cyro: 88.9%) and 6 months (CBA: 84.0%, Cyro: 43.8%; P = .0089). Cyroplasty as a modality for treatment of in-stent stenosis in the femoropopliteal segment offers no benefit over CBA.

Lower extremity limb salvage with cryoplasty: a single-center cohort study

Endovascular techniques have been playing an increasing role in managing lower extremity chronic critical limb ischemia (CLI) in patients considered poor or non-candidates for surgical revascularization secondary to co-morbidities such as coronary artery disease, uncontrolled hypertension, diabetes mellitus or inadequate conduit. This study reviews our recent clinical experience in the treatment of peripheral artery disease solely using cryoplasty. A retrospective cohort study was performed. The cohort consisted of 88 patients who underwent lower extremity revascularization utilizing cryoplasty between December 2003 and August 2007. Indications for intervention included poor wound healing after forefoot amputation or persistent ulceration of the foot, disabling claudication and rest pain. Kaplan–Meier analysis was performed to assess salvage rates. One hundred twenty-six lesions were treated in 88 patients. Technical success rate was 97%. Limb salvage rates were 75 and 63% for patients with critical limbs ischemia after one and three years, respectively. A history of smoking was associated with a threefold increased risk of limb loss. In conclusion, endovascular management of lower extremity lesions with cryoplasty is an emerging and viable paradigm in the treatment of CLI in an attempt to preserve limbs and avoid major amputations.

Cryoplasty versus conventional balloon angioplasty of the femoropopliteal artery in diabetic patients: long-term results from a prospective randomized single-center controlled trial

The purpose of this study was to investigate the immediate and long-term results of cryoplasty versus conventional balloon angioplasty in the femoropopliteal artery of diabetic patients. Fifty diabetic patients (41 men, mean age 68 years) were randomized to cryoplasty (group CRYO; 24 patients with 31 lesions) or conventional balloon angioplasty (group COBA; 26 patients with 34 lesions) of the femoropopliteal artery. Technical success was defined as <30% residual stenosis without any adjunctive stenting. Primary end points included technical success, primary patency, binary in-lesion restenosis (>50%), and freedom from target lesion recanalization. Cox proportional hazards regression analysis was performed to adjust for confounding factors of heterogeneity. In total, 61.3% (19 of 31) in group CRYO and 52.9% (18 of 34) in group COBA were de novo lesions. More than 70% of the lesions were Transatlantic Inter-Society Consensus (TASC) B and C in both groups, and 41.4% of the patients in group CRYO and 38.7% in group COBA suffered from critical limb ischemia. Immediate technical success rate was 58.0% in group CRYO versus 64.0% in group COBA (p = 0.29). According to 3-year Kaplan-Meier estimates, there were no significant differences with regard to patient survival (86.8% in group CRYO vs. 87.0% in group COBA, p = 0.54) and limb salvage (95.8 vs. 92.1% in groups CRYO and COBA, respectively, p = 0.60). There was a nonsignificant trend of increased binary restenosis in group CRYO (hazard ratio [HR] 1.3; 95% CI 0.6-2.6, p = 0.45). Primary patency was significantly lower in group CRYO compared with group COBA (HR 2.2; 95% CI 1.1-4.3, p = 0.02). Significantly more repeat intervention events because of recurrent symptoms were required in group CRYO (HR 2.5; 95% CI 1.2-5.3, p = 0.01). Cryoplasty was associated with lower primary patency and more clinically driven repeat procedures after long-term follow-up compared with conventional balloon angioplasty.

Initial Results of Concomitant Cryoplasty After Remote Endarterectomy of the Superficial Femoral Artery: A Feasibility Study (Cryoplasty Following Remote Endarterectomy)

Objective: Remote endarterectomy is a less invasive technique compared with supragenicular bypass surgery for superficial femoral artery (SFA) occlusive disease. Early restenosis remains one of the drawbacks of this procedure. To prevent restenosis following remote endarterectomy, concomitant cryoplasty of the desobstruct SFA was introduced.

Methods: A prospective cohort study was initiated with 17 patients treated with cryoplasty of the SFA after remote endarterectomy. Indications for surgery were claudication (n = 12), rest pain (n = 3), or tissue loss (n = 2).

Results: There were no technical failures. The Kaplan-Meier estimate of the primary and assisted primary patency rate after 1 year of follow-up was 74%. Secondary patency was 89%. Limb salvage was 100%. No aneurysmal degeneration and no other adverse events occurred during the follow-up.

Conclusions: This pilot study showed that cryoplasty after remote SFA endarterectomy is a safe procedure, with promising patency rates.

Restenosis after lower extremity interventions: current status and future directions

The incidence of restenosis after percutaneous peripheral interventions (PPI) varies considerably depending upon the vascular bed but appears to be highest in the femoropopliteal and tibioperoneal arteries. The restenosis process in the periphery does not appear to stop at the 6-month mark, as seen with bare metal stents in the coronary arteries, but continues for a longer time, possibly years, after the intervention. This review evaluates the incidence of restenosis following lower extremity arterial interventions and potential drugs or devices that could alter this process, including nonpharmacological (stents, cryoplasty, Cutting Balloon angioplasty, atherectomy, brachytherapy, and photodynamic therapy) and pharmacological (systemic and direct drug delivery) approaches. A global strategy to achieve optimal outcome with PPI is offered: (1) obtain excellent acute angiographic results with less dissection and recoil, (2) protect the distal tibial vascular bed, and (3) reduce smooth muscle cell proliferation with pharmacological intervention.

Which diabetics are at risk for lower-extremity problems and what preventive measures can be taken?

Diabetes mellitus is a well-known risk factor for development and progression of peripheral arterial disease. Prospective cardiovascular clinical trials have also clearly demonstrated that diabetics fare worse than their nondiabetic counterparts. Diabetics also differ from nondiabetics in that multiple revascularization procedures may be required in order for the clinical outcome to be equivalent to that of a nondiabetic patient. However, by advocating an aggressive approach to peripheral arterial disease, good results in survival and limb salvage can be achieved in diabetic patients despite the presence of increased medical comorbidities. Key to the management of such patients will be identifying which diabetic patients will be at most risk so that preventive measures can be undertaken.

Irreversible electroporation attenuates neointimal formation after angioplasty

Restenosis following coronary angioplasty represents a major clinical problem. Irreversible electroporation (IRE) is a nonthermal, nonpharmacological cell ablation method. IRE utilizes a sequence of electrical pulses that produce permanent damage to tissue within a few seconds.

METHODS AND RESULTS

The left carotid arteries of eight rats underwent in vivo intimal damage using two Fogarty angioplasty catheters. The procedure was immediately followed by IRE ablation in four rats, while the remaining four were used as the control group. The IRE ablation was performed using a sequence of ten dc pulses of 3800 V/cm, 100 micros each, at a frequency of ten pulses per second, applied across the blood vessel between two parallel electrodes. The electrical conductance of the treated tissue was measured during the electroporation to provide real-time feedback of the process. Left carotid arteries were excised and fixated after a 28-day follow-up period. Neointimal formation was evaluated histologically. The use of IRE was successful in three out of four animals in a way that is consistent with the measurements of blood vessel electrical properties. The integrity of the endothelial layer was recovered in the IRE-treated animals, compared with control. Successful IRE reduced neointima to media ratio (0.57 +/-0.4 versus 1.88 +/-1.0, P = 0.02).

CONCLUSIONS

We report for the first time the in vivo results of attenuation of neointimal formation using IRE. Our study shows that IRE might be able to attenuate neointimal formation after angioplasty damage in a rodent model of restenosis. This approach may open new venues in the treatment of coronary artery restenosis after balloon angioplasty.

Cryoplasty for peripheral vascular disease

BACKGROUND

In the UK, symptomatic peripheral arterial disease (PAD) occurs in 5 to 7% of people over the age of 55 years. Cryoplasty offers a new approach by combining the dilation force of balloon angioplasty with the delivery of cold thermal energy to the vessel wall. Cryoplasty is thought to provoke apoptosis rather than necrosis in the arterial smooth muscle cells and thus has the theoretical advantage of reduced myointimal hyperplasia in long-term patency. As it is an emerging therapy, safety and efficacy questions remain. This systematic review evaluates the treatment and provide focus for further research in the field.

OBJECTIVES

To assess the efficacy of, and complications associated with, cryoplasty for maintaining patency in the iliac or infrainguinal arteries.

SEARCH STRATEGY

We searched the Specialized Register of the Cochrane Peripheral Vascular Diseases Group (inception to August 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2007, Issue 3, along with MEDLINE (1966 to August 2007) and EMBASE (1980 to August 2007).

SELECTION CRITERIA

Trials in which patients with peripheral arterial disease (PAD) of the iliac or infrainguinal arteries were randomised to cryoplasty with or without another procedure versus a procedure without cryoplasty. This includes trials where all patients receive angioplasty and the randomisation is for cryoplasty versus none.

DATA COLLECTION AND ANALYSIS

Studies identified for potential inclusion were independently assessed for inclusion by at least two authors, with excluded trials arbitrated by the third author. As no randomised controlled trials of cryoplasty were found, no statistical analyses were performed.

MAIN RESULTS

No randomised controlled trials of cryoplasty were identified.

AUTHORS' CONCLUSIONS

The benefit of cryoplasty over conventional angioplasty has not been established as no randomised controlled trials exist to properly evaluate this method. Technical success and primary patency rates seen in the prospective series are encouraging and may suggest a future role for cryoplasty in the treatment of PAD, but cannot be reliably interpreted due to the nature of the studies.