Early rethrombosis in femoropopliteal occlusions treated with percutaneous transluminal angioplasty

Excimer Laser-Assisted Recanalization of Long, Chronic Superficial Femoral Artery Occlusions

Purpose:

To examine the safety and efficacy of excimer laser-assisted angioplasty (ELA) for recanalization of superficial femoral artery (SFA) occlusions.

Methods:

Data were analyzed from 318 consecutive patients (207 men; mean age 64.2 ± 10.7 years, range 33–91) who underwent ELA of 411 SFAs with chronic occlusions averaging 19.4 ± 6.0 cm in length. More than 75% of patients had severe claudication (category 3). Critical lower limb ischemia with rest pain or minor tissue loss was present in 6 and 15 patients, respectively. The mean ankle brachial index (ABI) before and after exercise was 0.62 ± 0.15 and 0.40 ± 0.18, respectively.

Results:

The initial attempt (crossover approach 89.7%, antegrade 6.6%, transpopliteal 3.6%) to cross the occlusion with an excimer laser catheter was successful in 342 (83.2%) of 411 limbs. A secondary attempt performed in 44 of 69 failed cases was successful in 30 limbs, increasing the technical success rate to 90.5% (372/411). Complications included acute reocclusion (4, 1.0%), perforation (9, 2.2%), and distal thrombosis/embolization (16, 3.9%). Postprocedurally, 219 (68.8%) patients were asymptomatic; mild (category 1) or moderate (category 2) claudication remained in 53 (16.6%) and 26 (8.2%) patients, respectively. The primary patency at 1 year was 33.6%. In the majority of patients, reocclusion was treatable on an outpatient basis. The 1-year assisted primary and secondary patency rates were 65.1% and 75.9%, respectively.

Conclusions:

Long SFA occlusions can be recanalized safely and successfully by ELA. However, to maintain patency and quality of life, intensive surveillance using objective testing followed by prompt repeat intervention are mandatory.

Antiplatelet and anticoagulant drugs for prevention of restenosis/reocclusion following peripheral endovascular treatment

BACKGROUND

Peripheral arterial disease (PAD) is frequently treated by balloon angioplasty. Restenosis/reocclusion of the dilated segments occurs often, depending on length of occlusion, lower leg outflow, stage of disease and presence of cardiovascular risk factors. To prevent reocclusion, patients are treated with antithrombotic agents. This is an update of a review first published in 2005.

OBJECTIVES

To determine whether any antithrombotic drug is more effective in preventing restenosis or reocclusion after peripheral endovascular treatment, compared to another antithrombotic drug, no treatment, placebo or other vasoactive drugs.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched 14 February 2012) and CENTRAL (2012, Issue 1).

SELECTION CRITERIA

We selected randomised controlled trials (RCTs). Participants were patients with symptomatic PAD treated by endovascular revascularisation of the pelvic or femoropopliteal arteries. Interventions were anticoagulant, antiplatelet or other vasoactive drug therapy compared with no treatment, placebo or any other vasoactive drug. Clinical endpoints were reocclusion, restenosis, amputation, death, myocardial infarction, stroke, major bleeding and other side effects, such as minor bleeding, puncture site bleeding, gastrointestinal side effects and haematoma.

DATA COLLECTION AND ANALYSIS

We independently extracted and assessed details of the number of randomised patients, treatment, study design, patient characteristics and risk of bias. Analysis was based on intention-to-treat data. To examine the effects of outcomes such as reocclusion, restenosis, amputation and major bleeding, we computed odds ratios (OR) with 95% confidence intervals (CI) using a fixed-effect model.

MAIN RESULTS

Twenty-two trials with a total of 3529 patients are included (14 in the original review and a further eight in this update). For the majority of comparisons, only one trial was available so results were rarely combined in meta-analyses. Individual trials were generally small and risk of bias was often unclear due to limitations in reporting. Three trials reported on drug versus placebo/control; results were consistently available for a maximum follow-up of only six months. At six months post intervention, a statistically significant reduction in reocclusion was found for high-dose acetylsalicylic acid (ASA) combined with dipyridamole (DIP) (OR 0.40, 95% CI 0.19 to 0.84), but not for low-dose ASA combined with DIP (OR 0.69, 95% CI 0.44 to 1.10; P = 0.12) nor in major amputations for lipo-ecraprost (OR 0.89, 95% CI 0.44 to 1.80). The remaining trials compared different drugs; results were more consistently available for a longer period of 12 months. At 12 months post intervention, no statistically significant difference in reocclusion/restenosis was detected for any of the following comparisons: high-dose ASA versus low-dose ASA (OR 0.98, 95% CI 0.64 to 1.48; P = 0.91), ASA/DIP versus vitamin K antagonists (VKA) (OR 0.65, 95% CI 0.40 to 1.06; P = 0.08), clopidogrel and aspirin versus low molecular weight heparin (LMWH) plus warfarin (OR 0.31, 95% CI 0.06 to 1.68; P = 0.18), suloctidil versus VKA: reocclusion (OR 0.59, 95% CI 0.20 to 1.76; P = 0.34), restenosis (OR 1.87, 95% CI 0.66 to 5.31; P = 0.24) and ticlopidine versus VKA (OR 0.71, 95% CI 0.37 to 1.36; P = 0.30). Treatment with cilostazol resulted in statistically significantly fewer reocclusions than ticlopidine (OR 0.32, 95% CI 0.13 to 0.76; P = 0.01). Compared with aspirin alone, LMWH plus aspirin significantly decreased occlusion/restenosis (by up to 85%) in patients with critical limb ischaemia (OR 0.15, 95% CI 0.06 to 0.42; P = 0.0003) but not in patients with intermittent claudication (OR 1.73, 95% CI 0.97 to 3.08; P = 0.06) and batroxobin plus aspirin reduced restenosis in diabetic patients (OR 0.28, 95% CI 0.13 to 0.60). Data on bleeding and other potential gastrointestinal side effects were not consistently reported, although there was some evidence that high-dose ASA increased gastrointestinal side effects compared with low-dose ASA, that clopidogrel and aspirin resulted in fewer major bleeding episodes compared with LMWH plus warfarin, and that abciximab resulted in more severe bleeding episodes.

AUTHORS' CONCLUSIONS

There is limited evidence suggesting that restenosis/reocclusion at six months following peripheral endovascular treatment is reduced by use of antiplatelet drugs compared with placebo/control, but associated information on bleeding and gastrointestinal side effects is lacking. There is also some evidence of variation in effect according to different drugs with cilostazol reducing reocclusion/restenosis at 12 months compared with ticlopidine and both LMWH and batroxobin combined with aspirin appearing beneficial compared with aspirin alone. However, available trials are generally small and of variable quality and side effects of drugs are not consistently addressed. Further good quality, large-scale RCTs, stratified by severity of disease, are required.

Adjunctive abciximab improves patency and functional outcome in endovascular treatment of femoropopliteal occlusions: initial experience

PURPOSE

To prospectively evaluate the safety and effectiveness of adjunctive administration of abciximab observed within 30 days and at 6 months after randomization in patients undergoing endovascular revascularization of long-segment femoropopliteal occlusions.

MATERIALS AND METHODS

The study was approved by the local ethical committee, and patients gave written informed consent. In a prospective, double-blind, placebo-controlled design, patients undergoing percutaneous treatment for long-segment (>5 cm) femoropopliteal occlusions were randomly assigned to receive abciximab or a placebo; all patients also received standard-dose heparin. Effectiveness and safety analyses were based on an intention-to-treat approach. Patency was calculated according to life-table analysis, and P values were derived from the log-rank statistic. The P values for dichotomous safety end points were calculated with the Fisher exact test. Odds ratios were calculated for subgroup analyses. Logistic regression modeling was used for analysis of the safety bleeding data.

RESULTS

A total of 98 patients (103 limbs) were included: 47 patients received abciximab and 51 received a placebo. Patency with abciximab versus placebo was 95.7% versus 80.4% (relative risk, 0.21; 95% confidence interval: 0.05, 0.96; P = .02) at 30 days and was 61.7% versus 41.2% (relative risk, 0.57; 95% confidence interval: 0.32, 1.01; P = .03), coupled with a better clinical outcome according to the Rutherford score, at the end of follow-up (P = .03). Risk of major bleeding was not significantly increased, while access-site bleeding was significantly higher among patients receiving abciximab (odds ratio, 2.9; 95% confidence interval: 1.04, 8.2; P = .04).

CONCLUSION

The data show that adjunctive administration of abciximab has a favorable effect on patency and clinical outcome in patients undergoing complex femoropopliteal catheter interventions not hampered by serious bleeding. Treatment effect of abciximab observed at 30 days was maintained at 6-month follow-up.

Antiplatelet and anticoagulant drugs for prevention of restenosis/reocclusion following peripheral endovascular treatment

BACKGROUND

Peripheral arterial disease (PAD) is frequently treated by balloon angioplasty. Restenosis/reocclusion of the dilated segments occurs often depending on length of occlusion, lower leg outflow, stage of disease and presence of cardiovascular risk factors. To prevent reocclusion, patients are treated with antithrombotic agents.

OBJECTIVES

To determine whether any antithrombotic drug is more effective in preventing reocclusion after peripheral endovascular treatment, compared to another antithrombotic drug, no treatment, placebo, or other vasoactive drugs.

SEARCH STRATEGY

We searched the Cochrane Peripheral Vascular Diseases Group's trials register (last searched April 2004), the Cochrane Central Register of Controlled trials (CENTRAL Issue 2, 2004), MEDLINE and EMBASE (last searched June 2004).

SELECTION CRITERIA

Randomised trials were categorised as A (double or single blinded) or B (not blinded). Participants included patients with symptomatic PAD treated by endovascular revascularisation of the pelvic or femoropopliteal arteries. Interventions were anticoagulant, antiplatelet or other vasoactive drug therapy compared with no treatment, placebo, or any other vasoactive drug. Clinical endpoints were re-obstruction, amputation, death, myocardial infarction, stroke and major bleeding.

DATA COLLECTION AND ANALYSIS

Details of the number of randomised patients, treatment, study design, study category, allocation concealment and patient characteristics were extracted. Analysis was based on intention-to-treat data. To examine the effects of binary outcomes such as amputation and major bleeding, odds ratios were computed using a fixed effect model. The 95% confidence intervals of the effect sizes were calculated.

MAIN RESULTS

A 60% reduction of recurrent obstruction was found with aspirin (ASA) 330 mg combined with dipyridamol (DIP) as compared to placebo at 12 months follow-up. At six months following endovascular treatment, a positive effect on patency was found with 50 to 100 mg ASA combined with DIP (n = 356). However, this was not significant. ASA/DIP tended towards showing a superior effect on patency after femoropopliteal angioplasty compared with VKA at three, six, and twelve months. Periinterventional treatment with LMWH in femoropopliteal obstructions resulted in significantly lower restenosis/reocclusion rates than with unfractionated heparin.

AUTHORS' CONCLUSIONS

Aspirin 50 to 300 mg started prior to femoropopliteal endovascular treatment appears to be the most effective and is safe. Clopidogrel might be an alternative, but data are lacking. Abciximab might be a useful adjunctive for high risk patients with long segmental femoropopliteal interventions. Low molecular weight heparin seems to be more effective in preventing reocclusion or restenosis than unfractionated heparin.

Subintimal angioplasty for chronic arterial occlusions

Percutaneous treatment of peripheral arterial disease has evolved greatly. The prevalence of superficial femoral artery occlusions has necessitated new devices and techniques to treat these patients percutaneously. Presently several therapies are available or under investigation. These range from stents, drug eluting stents, covered stents, cryoangioplasty, laser recanilization, blunt micro dissection, and subintimal angioplasty. This paper will discuss the indications, technique, and results of subintimal angioplasty.

Subintimal angioplasty of long superficial femoral artery occlusions

PURPOSE

To investigate the value of subintimal angioplasty (SA) and selective stent placement in the treatment of long (> or =15 cm) superficial femoral artery (SFA) occlusions.

MATERIALS AND METHODS

During a period of 4.5 years, 67 long SFA occlusions in 61 patients (52 male, 9 female) were intended to be treated with SA, either retrogradely (n = 55) or antegradely (n = 12). Postprocedural medical treatment included aspirin + ticlopidine/clopidogrel (AT/C) combination. In 25 patients warfarin was also given for 3-6 months. Patients were followed up for 1-30 months (mean 12.5 +/- 9.0 months). Hemodynamic patencies were determined with the Kaplan-Meier method, risk factors affecting patency were evaluated with the Cox model, and the patencies of the subgroups were compared with log-rank test.

RESULTS

Subintimal recanalization was technically successful in 59 of 67 occlusions. Technical success was 83% in the first 30 procedures, 92% in the last 37, and 100% in the last 29. Forty-six occlusions were treated with SA alone and 13 with SA and stent placement. On an intention-to-treat basis, primary patency at 6 and 12 months was 49% and 22%, respectively, and assisted primary patency at 6 and 12 months was 69% and 57%, respectively. Patency rates were not significantly different in patients with claudication versus critical limb ischemia, or in those treated with SA alone versus SA and stent placement. With the multivariate Cox model, medical treatment with AT/C combination was identified as the only significant risk factor for both primary patency and assisted primary patency. With the Kaplan-Meier analysis, primary and assisted primary patencies were significantly higher in the warfarin group than the AT/C group (P =.0002 and.0001, respectively).

CONCLUSION

SA is a simple and safe method with a high technical success rate in the endovascular treatment of long SFA occlusions. Long-term patency rates, however, seem unsatisfactory, despite early reports. Subintimal stent placement provides cumulative patency at least as good as SA alone. Warfarin may significantly improve both primary patency and assisted primary patency after subintimal recanalization, but even with this treatment patency rates are still lower than those reported for bypass surgery. Therefore, in long SFA occlusions, SA is not recommended for claudicants but may be valuable in patients with critical limb ischemia.

Potential use of a low-molecular-weight heparin to prevent restenosis in patients with extensive wall damage following peripheral angioplasty

The long-term outcome of primary successful percutaneous transluminal angioplasty (PTA) for patients with peripheral occlusive arterial disease (POAD) is frequently compromised by the development of restenosis, especially when extensive dissections result from the angioplastic procedure. Unfortunately, prevention of the occlusive process by means of drugs such as antithrombotics, anticoagulants, thrombolytics, corticosteroids, lipid reducers, or cytostatics has not been demonstrated convincingly. The authors sought to clarify whether such patients could benefit from the postsurgical administration of low-molecular-weight heparin. A total of 172 POAD patients with extensive dissections after PTA in the pelvic or upper leg regions were randomized for 7-day post-PTA intravenous treatment with either full heparinization or nadroparin calcium followed by adjunctive oral aspirin for 6 months. The primary outcome measure was the degree of stenosis (normal findings; stenosis < 50%, > 50%, > 80%, occlusion) before and after angioplasty, as well as 3 weeks and 3 and 6 months after dilation; secondary efficacy criteria included changes in the Fontaine stage and in the crurobrachial ratio. No significant treatment-related differences were found at the 3 post-PTA follow-up examinations with regard to the degree of stenosis. This was also the case for the subgroup of patients (n = 62) who had undergone angioplasty in the pelvic region. By contrast, when angioplasty was performed in the superficial femoral artery (n = 110), the degree of restenosis was significantly lower (p<0.01) among patients receiving nadroparin calcium compared to those given heparin at week 3, month 3, and month 6. No intergroup differences emerged for secondary outcome measures in the long term or for safety parameters. These preliminary results indicate that patients with extensive dissections after PTA treatment for POAD in the upper leg region might benefit from a reduction in the rate of restenosis by administration of 7-day weight-adjusted nadroparin calcium.

Percutaneous transluminal angioplasty for intracranial atherosclerotic lesions: evolution of technique and short-term results

OBJECT

A retrospective analysis of a 9-year experience with balloon angioplasty for intracranial atherosclerotic stenosis was undertaken with the goals of illustrating development of a safe technique for treatment of intracranial atherosclerotic disease and reporting the immediate results in this series of patients.

METHODS

Three distinct periods are defined, based on the technique used. In the early period, in which eight patients were treated, the angioplasty balloon size approximated the vessel size, but was always smaller. Angioplasty was moderately rapid and brief (15-30 seconds). Clinical improvement occurred in seven (87.5%) of eight patients, dissection without consequence occurred in four (50%) of eight, and residual stenosis greater than 50% was found in three (37.5%) of eight. No neurological complications occurred. In the middle period, in which 12 patients were treated, the balloon size approximated the vessel size, but oversizing by up to 0.25 mm was permitted. Angioplasty was extremely rapid and brief. Angiographically visible dissection occurred in nine (75%) of 12 patients, necessitating urokinase infusion in five (41.7%) of 12 and producing abrupt occlusion in one (8.3%) of 12, resulting in death. Occlusion secondary to the recrossing of the lesion occurred in one (8.3%) of 12, resulting in stroke. Good outcome was eventually achieved in 10 (83.3%) of 12. In the current period, in which 50 patients have been treated, the balloon is always undersized and inflation is extremely slow (several minutes). Dissection occurred in seven (14%) of 50 patients, necessitating fibrinolysis in two of 50 (4%, both uneventful) and producing no abrupt occlusion or stroke. Residual stenosis greater than 50% occurred in eight (16%) of 50, with no stenosis greater than 70%. Late restenosis occurred in four (9%) of 44 and successful repeated angioplasty was performed in all four. One guidewire vessel perforation occurred (2%), resulting in the patient's death. Good angiographic and short-term clinical outcome was achieved in the other 49 patients (98%).

CONCLUSIONS

Extremely slow balloon inflation combined with balloon undersizing results in decreased intimal damage, decreased acute platelet/thrombus deposition, and decreased acute closure. This technique sometimes yields suboptimal angiographic results but achieves the clinical goal safely. Intracranial angioplasty can be safely performed using this technique and modern equipment.

Percutaneous transluminal angioplasty and enclosed thrombolysis versus percutaneous transluminal angioplasty in the treatment of femoropopliteal occlusions: results of a prospective randomized trial

PURPOSE

To determine whether percutaneous transluminal angioplasty (PTA) and enclosed thrombolysis (ET) is superior to PTA alone in the treatment of femoropopliteal occlusions.

METHODS

Twenty-five patients with 5-15-cm-long occlusions in the femoropopliteal segments, with otherwise normal run-in arteries and at least one normal tibioperoneal artery to the foot, were randomized to ET/PTA or PTA alone. Ankle brachial systolic index (ABI) was measured before the procedure and at 24 hr and 12 months after the procedure, when a duplex scan was also carried out. End points in the study were patency at, or repeat intervention before, 12 months.

RESULTS

Procedures were successful in 23 of 25 patients. There was one immediate occlusion of tibioperoneal arteries, and one early reocclusion of a reopened segment in the ET/PTA group. There was one early reocclusion in the PTA group. At 12 months patency was 70% and 69.2% in the ET/PTA and PTA groups respectively. Covariant analysis showed no significant difference in ABI between the two groups at any of the three measurement times.

CONCLUSION

This trial demonstrated no difference between ET/PTA and PTA alone in femoropopliteal occlusions associated with normal proximal arteries and at least one normal tibioperoneal artery.

Effect of high dose verapamil on restenosis after peripheral angioplasty

OBJECTIVES

We sought to determine whether treatment with high dose verapamil prevents restenosis in patients at high risk for reoccurrence after successful percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Restenosis is the major limitation of PTCA. Calcium antagonists have demonstrated some potential as inhibitors of this process.

METHODS

A total of 98 patients with peripheral occlusive arterial disease (POAD), stable angina pectoris, mild hypertension and at least one additional risk factor increasing the likelihood of restenosis after angioplasty were selected for this placebo-controlled, double-blind, randomized trial. Verapamil (240 mg twice daily) or placebo was taken for 6 months. Efficacy variables assessed before and after angioplasty and at 6 weeks and 6 months after PTCA included thickness of the intima/media complex degree of stenosis, interventricular septal thickness, crurobrachial pressure ratios of dorsalis pedis and posterior tibial arteries, distance to claudication and total vessel diameter.

RESULTS

No significant intergroup differences emerged before or immediately after PTCA. Six weeks after angioplasty, a significant thickening of the intima/media complex in the treated vascular segment of 14.3% occurred in the placebo group versus 0% among verapamil patients (p < 0.01). At 6 months, the intima/media thickness was 35.7% greater in the placebo group but had decreased by 14.3% in the verapamil group (p < 0.001). At 6 months, a marked reduction in septal thickness was observed in the verapamil group versus that in the placebo group (p < 0.001). The rate of restenosis was also significantly lower in the verapamil group (p < 0.001). Few minor side effects were reported.

CONCLUSIONS

In patients with POAD at increased risk for restenosis, the administration of high dose verapamil prevented recurrent stenosis for 6 months after successful peripheral angioplasty and was well tolerated.

Efficacy of balloon angioplasty of the superficial femoral artery and popliteal artery in the relief of leg ischemia

PURPOSE

To assess the efficacy of balloon angioplasty in the superficial femoral artery (SFA) and popliteal artery for relief of lower-limb claudication and critical ischemia.

METHODS

All patients who underwent SFA or popliteal balloon angioplasty at the Royal Adelaide Hospital between January 1989 and September 1994 were reviewed. Risk factors, indications, angiographic variables, and complications were assessed. Outcome was expressed in life-table form as patency, limb survival, and patient survival rates.

RESULTS

One hundred seventy-six patients (96 men, 80 women) who underwent 200 balloon angioplasty procedures were monitored for a mean of 25 months. Seventy-four percent of procedures were for claudication relief and 26% for critical ischemia. The cumulative patency rate at 24 months for all cases was 46%. The limb salvage rate was 95%, and the patient survival rate was 91% at 24 months.

CONCLUSION

Percutaneous transluminal angioplasty of the SFA and popliteal arteries is commonly used to treat claudication and critical ischemia but is associated with a high initial failure rate and poor patency at 24 months. Balloon angioplasty is not recommended to treat claudication.

Risk factors leading to arterial occlusion following diagnostic arteriography

OBJECTIVES

Arteriography may precipitate occlusive complications in stenotic vessels by a toxic effect on the vascular endothelium, leading to intra-arterial thrombosis. The aim of this retrospective study was to determine the incidence of arterial occlusion following arteriography.

METHODS

We studied 101 consecutive patients (71 male, 30 female; median age 72 years) undergoing percutaneous transluminal angioplasty (PTA) of stenotic lesions, which had been identified on diagnostic arteriograms performed a median of 109 days (range 6-519) previously. One hundred and thirty-one arterial stenoses suitable for PTA were identified in the patient cohort.

RESULTS

Seventeen patients (17%) progressed to occlusion in the period between diagnostic arteriography and PTA. Stenoses in the femoro-popliteal segment (21%) progressed to occlusion more frequently than lesions of the iliac arteries (3%). Independent risk factors were analysed to determine the risk factors predisposing to arterial occlusion following diagnostic arteriography. Both groups were well matched for age and sex. The mode of presentation, the presence of ischaemic heart disease, hypertension, diabetes or current smoking habits did not predict progression of disease to arterial occlusion. However, the rate of occlusion appeared to be influenced by the proportion of patients taking anti-platelet medication (51% in non-occluders as compared to 11% in patients who occluded, 95% CI 0.1 to 10), and to the length of time between arteriography and PTA (median of 92 days in non-occluders as compared to 125 days in patients who occluded, 95% CI 21 to 57).

CONCLUSIONS

These data demonstrate that occlusion of pre-existing arterial stenoses following diagnostic arteriography is significantly more frequent in patients not taking anti-platelet medication and when the time interval between arteriography and PTA exceeds 92 days. To minimise thrombotic arterial occlusion both diagnostic and therapeutic procedures should be performed simultaneously, but if a delay is unavoidable, patients should be treated with anti-platelet medication, which reduces the incidence of arterial occlusion.

Lysis-assisted angioplasty in the treatment of lower-limb arterial thrombosis

This study examined the results in 30 patients treated with lysis-assisted angioplasty and compared them with the results of 30 patients with simple stenotic disease treated by angioplasty alone. One patient died on the day of treatment with lysis-assisted angioplasty from arterial perforation and haemorrhage. Of the remaining 29 patients 16 (55 per cent) were symptomatically improved and 13 had early reocclusion. Six patients developed major complications (two deaths, two major haemorrhage, two cerebrovascular accident). The late results were comparable to those for patients undergoing angioplasty alone. The best outcome was obtained in patients with proximal disease (P < 0.01); poor run-off or critical ischaemia did not preclude a good outcome.

Attachment, replication and thrombogenicity of genetically modified endothelial cells

Endothelial cell seeding of prosthetic surfaces has been proposed as a technique to improve the patency of vascular grafts following arterial reconstruction. The introduction of specific recombinant DNA into seeded endothelial cells may enhance the anti-thrombogenic nature of the endothelial-blood interface with a consequent reduction in graft thrombosis. However, the successful use of genetically modified endothelial cells in the seeding process relies on the cells retaining normal function in terms of cellular replication, attachment and secretion of anti-thrombotic mediators. Successful genetic manipulation of human endothelial cells has been accomplished by viral and chemical methods.

AIM

To study the functional characteristics of electrontransfected endothelial cells.

METHODS AND RESULTS

Endothelial cells were electro-transfected with the test plasmid pTCF at a transfection efficiency of 10% utilising a single electric pulse with an electric field of 1000 volts/cm and a time constant of 12.8ms. The functional status of transfected endothelial cells was then compared with a control endothelial cell population. There were no significant differences in replication (p = 0.76), attachment (p = 0.43), basal (p = 0.89) or stimulated (p = 0.11) prostacyclin release between transfected cells as compared with control endothelial cells.

CONCLUSIONS

Genetically modified cells are functionally normal, and may be used in endothelial cell seeding of prosthetic vascular surfaces.

Percutaneous laser recanalisation of femoropopliteal occlusions using continuous wave Nd-YAG laser and sapphire contact probe delivery system

A conventional continuous wave Nd-YAG medical laser system delivered by transparent sapphire tipped optical fibres was used for percutaneous recanalisation of 32 chronic femoropopliteal occlusions in 27 patients (19 men, eight women; median age 68 years, range 46-83 years). Twenty-four patients had severe intermittent claudication and three had critical ischaemia. The median occlusion length was 8 cm (range 3-35 cm) and lesions were not negotiable by guidewire. Laser energy was delivered at powers of 10-15 Watts using intermittent 1 second emissions (mean total energy 315 Joules, range 30-1015]). The sapphire tips used were 1.8 to 3.0 mm diameter. After laser recanalisation adjunctive balloon dilatation was necessary to widen the resulting lumen. All patients received anti-platelet therapy. Initial clinical success was achieved in 22 limbs (69%) with symptomatic relief and increase in mean (+/- S.D.) ankle-brachial pressure ratio from 0.52 (+/- 0.25) to 0.80 (+/- 0.21) [Mann-Whitney U, p < 0.001]. Recanalisation was unsuccessful in all calcified lesions (four cases). There was a high incidence of vessel perforation (28%) and wall dissection (25%). Emergency surgery was not required after failed procedures. The median follow-up was 12 months (range 6-20 months). By 6 months, 15 of 22 successfully recanalised lesions (68%) had reoccluded. The cumulative primary patency at 1 year was only 12%. These disappointing results do not support routine use of this system. Clearly, modifications of the laser/delivery system or the technique, or both, are required. The aim should be to achieve sole laser recanalisation without concomitant balloon dilatation.

Serial investigation of balloon angioplasty induced changes in the superficial femoral artery using colour duplex ultrasonography

Percutaneous transluminal balloon angioplasty (PTA) of superficial femoral artery lesions is associated with similar initial success rates in coronary and iliac artery angioplasty but its application is limited by a much higher incidence of restenosis. To improve understanding of the trauma caused to the vessel by balloon angioplasty and the mechanisms contributing to the subsequent processes of healing and restenosis requires serial investigations of the treated arteries in vivo. This paper describes a prospective study using colour duplex ultrasonic imaging to assess arterial changes in 51 patients with atherosclerotic disease undergoing PTA of superficial femoral artery stenoses and occlusions. Each patient was scanned prior to angioplasty and at intervals up to 6 months post-angioplasty. On each scan, measurements were made of the overall vessel and lumen diameters at each site of angioplasty. These measurements indicate that angioplasty improves vessel patency mainly by stretching of the vessel wall, with compression and/or redistribution of the atherosclerotic plaque contributing less than 25% to the improvement of lumen diameter. Serial measurements after angioplasty show complex patterns of change at the angioplasty sites indicating that several mechanisms may be contributing to the processes of vessel healing and subsequent restenosis. Possible mechanisms which could explain the measured changes in overall vessel and lumen diameters are discussed.

Thrombosis and intrinsic fibrinolysis in percutaneous transluminal angioplasty

Coagulation and fibrinolysis were investigated in 14 claudicants undergoing percutaneous transluminal angioplasty (PTA) for femoropopliteal artery lesions. Cross-linked fibrin degradation products (XL-FDP), tissue plasminogen activator (t-PA) antigen, fibrinopeptide A (FPA), and plasminogen activator inhibitor-1 (PAI-1) activity were measured in peripheral blood. XL-FDP and t-PA increased, and FPA and PAI-1 decreased significantly after angioplasty. XL-FDP increased from baseline 266 +/- 72 ng/ml to 481 +/- 239 ng/ml (p < 0.0005) 30 min after PTA, indicating mural thrombus formation in spite of the significant fall in FPA influenced by heparin. A groin haematoma developed after PTA in 4/6 patients, who received more than 5600 IU heparin and in 1/8 patients receiving smaller dosages. The alterations in PAI-1 showed no correlation with those of t-PA, whereas heparin had a sparing effect on PAI-1 consumption. These findings may indicate that PAI-1 acts as a thrombin inhibitor following deep vessel wall injury by angioplasty. In two patients, who had signs of rethrombosis on the next day, residual FPA was relatively high, XL-FDP peaked at 3530 +/- 1170 ng/ml, and t-PA increased by 2.6 +/- 1.0 ng/ml. The corresponding values in patients with an uncomplicated course were 406 +/- 89 ng/ml (p < 0.0001) and 0.1 +/- 0.5 ng/ml (p < 0.02). We conclude that thrombin promotes activation of coagulation and fibrinolysis in femoropopliteal PTA. Instability between these counteracting systems resulting in thrombosis is not prevented by conventional heparin administration at dosages causing bleeding complications.

Platelet deposition after angioplasty is abolished by restoration of the endothelial cell monolayer

PURPOSE

Percutaneous transluminal angioplasty of an atheromatous plaque causes endothelial desquamation and intimal dissection with the consequent formation of a thrombogenic flow surface. In this study we investigated the hypothesis that platelet deposition after balloon angioplasty may be decreased by rapid restoration of the endothelial cell monolayer, achieved by transluminally seeding angioplasty sites with endothelial cells.

METHODS

Bilateral external iliac angioplasty was performed in eight New Zealand white rabbits. One angioplasty site was isolated from the circulation and incubated with a supraconfluent endothelial cell suspension with a double balloon catheter; the contralateral angioplasty site was sham seeded with culture medium. The deposition of autologous indium 111-labeled platelets on the angioplasty sites was quantified 30 minutes after restoration of flow and was referenced to an undamaged segment of aorta that acted as a negative control.

RESULTS

Platelet deposition on the nonseeded angioplasty site (13.1 x 10(4) platelets/mm2) was significantly higher than on nondilated segments (3.4 x 10(4) platelets/mm2; p = 0.014). Restorationof endothelial cell coverage by endothelial seeding significantly reduced platelet deposition on dilated arterial segments to levels not significantly higher than in controls (3.6 x 10(4) platelets/mm2; p = 0.014).

CONCLUSIONS

These results illustrate that rapid reendothelialization of angioplasty sites decreases subsequent platelet deposition and may reduce the rate of acute arterial reocclusion complicating endovascular techniques.

Femoropopliteal angioplasty for severe limb ischaemia

Fifty patients undergoing 51 percutaneous transluminal angioplasties of the femoropopliteal segment for severe limb ischaemia were reviewed regularly. They comprised 30 men and 20 women of median age 70 (range 56-85) years. There were two deaths within 30 days. At 2 years the cumulative patient survival rate was 60 per cent. Eleven angioplasties were technical failures, 25 failed in the first 6 months and 14 were successful at 6 months' follow-up; in addition one patient died from myocardial infarction within 30 days of technically successful angioplasty. Subsequent vascular procedures were successful in 11 limbs following failed angioplasty. The primary limb survival rate was 42 per cent at 2 years. There were eight major complications after angioplasty, requiring amputation in five instances. Of the 23 long occlusions (greater than 5 cm) that were recanalized and dilated, 22 procedures failed within 6 months. The run-off score and diabetic status did not predict outcome. In this group of patients angioplasty had a low durability. Dilatation of long occlusions is associated with high rates of reocclusion and, on the basis of these results, should not be performed.

Cross-linked fibrin degradation products (XL-FDP) as marker of early rethrombosis in percutaneous transluminal angioplasty

The thrombotic response to percutaneous transluminal angioplasty (PTA) was investigated in 31 patients treated for 1-10 cm femoropopliteal (n = 28) and tibial (n = 3) artery obstructions by measurement of cross-linked fibrin degradation products (XL-FDP) in peripheral blood samples drawn before and 30 min after PTA. XL-FDP increased from 400 +/- 147 ng/ml to 700 +/- 445 ng/ml (median +/- S.E., p = 0.0005). XL-FDP rose from 320 +/- 110 ng/ml to 540 +/- 102 ng/ml in 23 patients, whose ankle/brachial systolic blood pressure index (ABI) increased > 0.15 after PTA, whereas XL-FDP increased from 850 +/- 450 ng/ml to 2620 +/- 1472 ng/ml in eight patients, who failed to increase ABI in spite of preceding recanalisation. XL-FDP increased by more than 1000 ng/ml in 1/23 (4.3%) patients with uncomplicated PTA and in 6/8 (75%) patients with haemodynamic failure (p = 0.0005). Using a XL-FDP increase of 1000 ng/ml as cut-off, estimates of positive and negative predictive values (95% confidence limits) for early failure of PTA were 85.7% (42.1-99.6%) and 91.7% (73.0-99.0%), respectively. We conclude from this pilot study that femorotibial PTA produces a hypercoagulable state which may result in failure of early patency due to rethrombosis. We suggest for the first time XL-FDP as a marker of early rethrombosis in PTA, and report a sequential XL-FDP assay which may be useful for identification of high-risk patients requiring thrombolytic therapy after PTA for maintenance of early vascular patency.

Effect of seeding time and density on endothelial cell attachment to damaged vascular surfaces

An in vitro model to facilitate the study of endothelial cell seeding of damaged vascular surfaces has been developed. This may have applications in the study of endothelial seeding of angioplasty and endarterectomy sites. Using this model, the optimum endothelial seeding time for attachment to damaged vascular surfaces should not exceed 30 min and, to achieve confluent cell attachment, a seeding density > 5 x 10(5) cells/cm2 should be used.

Endothelial cell seeding of damaged native vascular surfaces: prostacyclin production

Endothelial cell seeding has been successful in reducing the thrombogenicity of prosthetic vascular grafts in animal and clinical studies. The reduction in thrombogenicity may be attributed to the intrinsic properties of endothelial cells themselves, and their ability to produce anti-thrombogenic mediators such as prostacyclin, and endothelium-derived relaxing factor. Endothelial seeding of damaged vascular surfaces produced during percutaneous transluminal angioplasty and endarterectomy is an attractive possibility due to the excellent attachment characteristics of the sub-endothelial tissue exposed during these procedures. The ability of endothelial seeded damaged vascular surfaces to produce prostacyclin was measured in an in vitro model of vascular injury. Endothelial-seeded damaged surfaces produced significantly higher prostacyclin release than did vessels damaged by balloon dilatation (265.5 pg cm-2 min-1 and 87.5 pg cm-2 min-1 respectively). This study provides evidence that endothelial seeding of damaged native vascular surfaces is technically feasible and that seeding may reduce the thrombogenicity of vascular surfaces following balloon dilatation.

Factors that influence the outcome of aortoiliac and femoropopliteal percutaneous transluminal angioplasty

In the past, patients with peripheral arterial occlusive disease were managed by conservative treatment or by vascular reconstructive surgery. Now, percutaneous transluminal angioplasty and other endovascular methods provide an important alternative for managing selected patients with peripheral arterial occlusive disease. Overall, the 5-year success rate after iliac angioplasty is 53.4%, but the success rate is higher if percutaneous transluminal angioplasty is performed on the common iliac artery or on a stenosed artery. In contrast, percutaneous transluminal angioplasty of the femoral and popliteal arteries has a relatively poor long-term success rate except for the treatment of patients with stenoses with good run-off. When the run-off is poor or an arterial occlusion is present, the role of femoropopliteal angioplasty is limited, and the procedure should be considered only for high-risk patients who do not have autogenous tissue for reconstructive surgery.

Endovascular surgery for peripheral arterial occlusive disease. A critical review

Endovascular surgery is a new multidisciplinary field that applies the recently innovated techniques of angioscopy, intraluminal ultrasound, balloon angioplasty, laser, mechanical atherectomy, and stents. This field can be defined as a diagnostic and therapeutic discipline that uses catheter-based systems to treat vascular disease. As such, it integrates the subspecialties of vascular surgery, interventional radiology, interventional cardiology, and biomedical engineering for the common purpose of improving arterial hemodynamics. Endovascular surgery offers many potential benefits: long incisions are replaced with a puncture wound, the need for postoperative intensive care is significantly reduced, major cardiac and pulmonary complications from general anesthesia are side stepped, and the dollar savings could be dramatic as the need for intensive care unit and in-hospital stay diminishes. Despite these technological advancements, endovascular surgery is still in its infancy and currently has limited applications. This review provides an updated summary of endovascular surgery today and addresses some of the obstacles still preventing its widespread use.

Intra-arterial thrombin activity produced by percutaneous transluminal angioplasty eliminated by segmentally enclosed thrombolysis

We determined the specific marker of thrombin activity, fibrinopeptide A (FPA), in the vicinity of dilated sites during percutaneous transluminal angioplasty (PTA) for femoro-popliteal obstructions in 24 patients. Blood samples were drawn proximal to dilated segments from a 4F catheter inserted retrogradely in the common femoral artery and distal to dilated segments from the balloon catheter tip. Median +/- S.E. FPA concentration was 21.5 +/- 4.4ng ml-1 before PTA. Immediately after dilatation, FPA concentrations were increased to 970.0 +/- 836.9 ng ml-1 distal to dilated segments (p less than 0.00005) and to 48.5 +/- 11.4 ng ml-1 proximally (p less than 0.003). Segmentally enclosed thrombolysis (SET) was undertaken immediately after PTA, when a double balloon catheter was positioned with a balloon at each end of dilated segments. Both balloons were inflated and 5 mg recombinant tissue plasminogen activator (rt-PA) and 1000 IU heparin were enclosed in the segments for 30 min. Immediately after SET, FPA concentration distal to dilated segments was 34.0 +/- 14.2 ng ml-1 and not different from proximal concentrations found after PTA (p = 0.57). Intense fibrinolysis was indicated by significantly increased levels of cross-linked fibrin degradation products (D-dimer) for hours after SET, but FPA concentrations in peripheral blood remained near baseline values. This finding differed from increased thrombin activity found by others during systemic thrombolytic therapy. Early rethrombosis did not occur after PTA in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Segmentally enclosed thrombolysis in percutaneous transluminal angioplasty for femoropopliteal occlusions: a report from a pilot study

Segmentally enclosed thrombolysis (SET) was performed immediately following 34 percutaneous transluminal angioplasties (PTAs) for femoropopliteal occlusions. The dilated segment was sealed off with a double balloon catheter, and recombinant tissue plasminogen activator (rt-PA) 1 mg/ml and heparin 200 IU/ml were injected between the balloons. The catheter was removed after 30 min and heparin treatment was continued for 24 h. Alpha-2-antiplasmin was initially reduced by 13% and normalized 2 h after SET, indicating that only small amounts of free plasmin were liberated during thrombolysis. No clinically relevant changes in plasma fibrinogen occurred. Two puncture site hemorrhages did not coincide with the coagulopathy induced by SET. One-year patency was 80%. Early rethrombosis occurred in 9% versus 41% in our previous series on standard PTA for femoropopliteal occlusions (p less than 0.001). Therefore, SET is considered beneficial in reducing the incidence of early rethrombosis.

Late hemodynamic failure following percutaneous transluminal angioplasty for long and multifocal femoropopliteal stenoses

The outcome of percutaneous transluminal angioplasty (PTA) was evaluated for treatment of 87 limbs with femoropopliteal stenoses, including 55 short stenoses (2.4 +/- 1.6 cm, mean +/- SD), seven single long stenoses (10.4 +/- 2.0 cm), and 25 multifocal stenoses (2.1 +/- 1.6 cm), where two to four separate segments were dilated. Following 98% initial technical success, 3-year patency was 68% for single short stenoses, as opposed to 20% for long and multifocal stenoses (p = 0.05, logrank test). Antiplatelet therapy with acetylsalicyclic acid was not found to influence occurrence of restenosis. The study documents the poor PTA results for long and multifocal stenoses and suggests precautions to be taken during PTA in order to minimize the area of artery wall damage.

Femoro-popliteal artery occlusions treated by percutaneous transluminal angioplasty and enclosed thrombolysis: results in 55 patients

Removal of fibrin from the site of a newly dilated femoro-popliteal occlusion may be an attractive way of preventing rethrombosis. A double balloon catheter with a dilating tip balloon and an occlusive balloon 10, 15 or 20 cm approximately were introduced percutaneously. Following successful dilatation of femoro-popliteal occlusions, the balloons were inflated on both sides of the lesion. The dilated segment was then isolated from the circulation. Through a sideport between the balloons 5 mg of tissue type plasminogen activator and 1000 IU of heparin were installed within the segment for 30 min. The authors report the results of 53 technically successful dilatations of femoro-popliteal occlusions followed by enclosed thrombolysis. A 100% patency at 3 months was noted in 33 patients having one to three run-off arteries, and the one year patency was 90%. In 20 patients, with no infrapopliteal run-off artery, four rethrombosis occurred within 24 h, and the one year patency was 62%. This difference is significant. (Log rank test, Chi-square = 4.73, p less than 0.05). We conclude that enclosed thrombolysis prevents early reocclusion following PTA of femoro-popliteal occlusions provided that at least one infra-popliteal artery is patent.