New technologies for the treatment of obstructive arterial disease

Laser Atherectomy for Lower Extremity Revascularization: An Adjunctive Endovascular Treatment Option

Excimer laser atherectomy (LA) employs precision laser energy control (shallow tissue penetration) and safer wavelengths (ultraviolet as opposed to the infrared spectra in older laser technology), which decreases perforation and thermal injury to the treated vessels. Though extensively used by cardiologists for severe obstructive coronary artery disease, peripheral interventionalists have not accepted LA as a routine adjunctive technique for stenotic or occluded vessels. We report herein the technical and clinical outcomes with LA for complex peripheral vascular disease in patients deemed high-risk for conventional surgical revascularization. Over a 6-month period, 19 lesions in 15 high-risk patients (mean age 72 ±10 years) were treated with LA (308-nm spectral wavelength) followed by balloon angioplasty for limb-threatening ischemia (n=10) and severe disabling claudication (n=5). The lesions were located at the superficial femoral artery (n=8), popliteal artery (6), and/or tibial vessels (5). The mean occlusion length was 10.3 ±2.3 cm. Laser catheter choice ranged from 1.4 to 2.5 mm depending on the target vessel diameter. Clinical examination, duplex ultrasound, and ankle-brachial indices were performed in follow-up visits. Immediate technical success was achieved in 16 (84%) lesions. In the 3 technical failures, inability to cross the lesion with a wire (n=2) or vessel perforation (n=1) precluded successful LA. Overall, primary patency as assessed by duplex was 57% (superficial femoral artery 71%, popliteal 60%, tibial vessels 25%). Clinical improvement was seen in 10 lesions (77%) that were successfully treated initially. One patient required below-knee amputation. At an average of 2-year follow-up, 6 patients who were initially successfully treated were alive (46%), including 3 patients (50%) with stable symptoms without the need for major amputation. Laser atherectomy is a useful adjunctive revascularization technique for high-risk patients with limb-threatening ischemia. This technique is especially beneficial in the treatment of ostial lesions, which may be prone to distal embolization, as well as total occlusions that can be traversed by a guide wire but not a balloon. Vascular surgeons should add LA to their endovascular armamentarium for the treatment of complex peripheral vascular disease in the high surgical risk patients. Further study of clinical outcome measures and comparison to other interventional techniques are warranted.

Computerized analysis of myocardial echocardiographic enhancement during coronary revascularization by high-speed rotational atherectomy

A previous report demonstrated transient myocardial echocardiographic contrast (MEC) enhancement following high-speed rotational atherectomy (HSRA). This phenomenon was found to be correlated to the speed and duration of rotation and related to creation of cavitations. To determine other correlations and the significance of MEC, continuous echocardiographic recording was performed in 10 patients undergoing HSRA. Images were digitized and videointensity-time curves generated. Curve parameters were calculated and correlated with procedural variables, plaque mass, and side effects. Twenty-nine ablation passes in 10 patients were analyzed. Videointensity peaked 9-44 sec from initiation of ablation and decayed to a higher baseline level after each consecutive ablation. Increase in peak contrast intensity (PCI) from baseline and the percentage of the left ventricle undergoing enhancement were highest (33 +/- 31 gray level/pixel and 32% +/- 8%, mean +/- SD, respectively) after the second rotation and were not influenced by the duration of rotation. PCI, side effects, and transient left ventricular wall motion abnormalities were positively correlated with plaque mass, defined by the product of lesion length, diameter, and percent stenosis. HSRA resulted in significant myocardial echocardiographic contrast. PCI is related to ablation sequence and plaque mass. Plaque debris embolization is probably responsible for myocardial echocardiographic contrast and transient wall motion abnormalities. Cathet. Cardiovasc. Intervent. 49:39-44, 2000.

Peripheral atherectomy with the Pullback Atherectomy Catheter: procedural safety and efficacy in a multicenter trial. PAC Investigators

PURPOSE

To report the initial results of a newly designed catheter for percutaneous circumferential atherectomy in patients with lower extremity atherosclerotic occlusive disease.

METHODS

The Pullback Atherectomy Catheter (PAC) is an over-the-wire device that circumferentially debulks atherosclerotic lesions in peripheral arteries up to 6 mm in diameter. Pullback atherectomy with or without adjunctive balloon angioplasty was attempted in 190 patients (246 lesions) with lower extremity lesions < or = 7.0 cm in length and a diameter stenosis > 50%.

RESULTS

Angiographic success was accomplished in 95% (234/246) of the of the lesions attempted. The baseline ankle-brachial index rose from 0.61+/-0.20 to 0.83+/-0.20 (p < 0.001) at 24 hours after the procedure. There were no major complications (distal emboli, dissection, thrombosis, or perforation requiring surgical correction) attributable to pullback atherectomy.

CONCLUSIONS

The acute results of pullback atherectomy demonstrate an extremely high technical success rate and an excellent safety record for lower extremity percutaneous revascularization. The catheter facilitates debulking longer lesions, but it is limited to small-diameter (< or = 6 mm) peripheral vessels.

Peripheral Atherectomy with the Pullback Atherectomy Catheter: Procedural Safety and Efficacy in a Multicenter Trial

Purpose:

To report the initial results of a newly designed catheter for percutaneous circumferential atherectomy in patients with lower extremity atherosclerotic occlusive disease.

Methods:

The Pullback Atherectomy Catheter (PAC) is an over-the-wire device that circumferentially debulks atherosclerotic lesions in peripheral arteries up to 6 mm in diameter. Pullback atherectomy with or without adjunctive balloon angioplasty was attempted in 190 patients (246 lesions) with lower extremity lesions ≤ 7.0 cm in length and a diameter stenosis > 50%.

Results:

Angiographic success was accomplished in 95% (234/246) of the of the lesions attempted. The baseline ankle-brachial index rose from 0.61 ± 0.20 to 0.83 ± 0.20 (p < 0.001) at 24 hours after the procedure. There were no major complications (distal emboli, dissection, thrombosis, or perforation requiring surgical correction) attributable to pullback atherectomy.

Conclusions:

The acute results of pullback atherectomy demonstrate an extremely high technical success rate and an excellent safety record for lower extremity percutaneous revascularization. The catheter facilitates debulking longer lesions, but it is limited to small-diameter (≤ 6 mm) peripheral vessels.

Introduction to coronary artery stents and their pharmacotherapeutic management

OBJECTIVE

To provide an introduction to coronary artery stents and their pharmacologic management, including anticoagulant therapy and newer antiplatelet regimens.

DATA SOURCES

A MEDLINE and current journal search of relevant articles that evaluated coronary stent success rates and anticoagulation or antiplatelet regimens.

STUDY SELECTION

Data from the use of primarily the Palmaz-Schatz stent were included. Studies using vitamin K antagonists that are not commercially available in the US were excluded unless they compared an antiplatelet regimen with anticoagulation using the international normalized ratio (INR).

DATA SYNTHESIS

Limitations with percutaneous transluminal coronary angioplasty (PTCA), such as ischemic complications and restenosis, have led to the advent of intracoronary stenting. However, the placement of a stent within the coronary artery lumen is associated with a risk of thrombotic events. Despite current postprocedural anticoagulation and antiplatelet regimens, thrombosis occurs at rates ranging from 0.6% to 21%. When anticoagulation is deemed appropriate, it should be used for 1-2 months and the INR should be maintained between 2 and 3.5. Anticoagulation appears to have no effect on the development of restenosis, but has been shown to cause significant hemorrhagic events in 5-13.5% of patients. Newer data continue to define the subsets of patients who may be managed with antiplatelet agents alone. Combinations of aspirin and ticlopidine or aspirin alone may be used to manage patients who fulfill the following criteria: optimal stent placement, high-pressure inflation, and adequate coronary size.

CONCLUSIONS

Coronary artery stenting is a novel approach for the management of coronary artery disease, but is associated with the complication of stent thrombosis. Anticoagulation reduces the risk of stent thrombosis, but is associated with bleeding risk. Selected patients may be successfully managed with antiplatelet agents only. More data are needed to better define the optimal antithrombotic regimen.

Comparative study of Nd:YAG laser angioplasty at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths: decreased vascular spasm and early mortality with 1.44 microns laser ablation

BACKGROUND AND OBJECTIVE

Although laser angioplasty has been demonstrated to be effective for the treatment of long, complex coronary arterial atherosclerotic stenoses, there is an associated risk of acute arterial spasm, dissection, and perforation as well as a significant restenosis rate. It has been postulated that the use of lasers emitting at wavelengths designed for radiation absorption by water would decrease local tissue trauma.

STUDY DESIGN/MATERIALS AND METHODS

We have examined the use of a Nd:YAG laser designed to emit at 1.44 microns, an absorption peak for water, and compared the results of laser ablation at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths. Nd:YAG laser angioplasty was performed in the abdominal aorta of White Leghorn roosters. Acute and chronic vascular trauma was assessed by contrast angiography and histological analysis.

RESULTS

There was a significant decrease in early mortality with 1.44 microns laser ablation. This decreased mortality after 1.44 microns ablation was associated with a decrease in vascular spasm, perforation, and thermal damage. Atherosclerotic plaque development at follow up was decreased with 1.44 microns ablation but this was not significant.

CONCLUSION

1.44 microns laser ablation decreases early vascular trauma and mortality and may decrease subsequent atherosclerotic plaque development.

Excimer laser induced bubble: dimensions, theory, and implications for laser angioplasty

BACKGROUND AND OBJECTIVE

Previous studies have demonstrated that during Xenon-Chloride excimer laser ablation of tissue, rapidly expanding and imploding bubbles (diameter < 3 mm), predominantly containing water vapor, are formed. These short lived bubbles (life time < 300 microseconds) induce mechanical damage in adjacent tissue. In the present study, a theoretical analysis of the volume of vaporized water is correlated with measured bubble volumes formed in hemoglobin solution.

STUDY DESIGN/MATERIALS AND METHODS

The dimensions of the rapidly expanding and imploding vapor bubble induced by the XeCl excimer laser pulses (308 nm, 115 ns), delivered via a 300, 550, or 950 microns diameter monofiber in 16% w/v hemoglobin solution (at 37 degrees C), were measured.

RESULTS

Theoretical analysis and the experimental data correlated well (correlation coefficient r = 0.97). The diameter of excimer laser induced bubbles increased with increasing pulse energy. For a given radiant exposure, the bubble size was decreased by either decreasing the fiber tip area or by decreasing the absorption coefficient of the hemoglobin solution.

CONCLUSION

We conclude that, for a wide range of conditions, theory agrees well with experimental data. Thus, during delivery of excimer laser pulses in blood, bubble dimensions can be reduced by flushing with saline or by reduction of the area radiated with each laser pulse, for example, by pulse multiplexing or using a smaller multifiber catheter.

Infected iliac pseudoaneurysm after uncomplicated percutaneous balloon angioplasty and (Palmaz) stent insertion: a case report and literature review

Percutaneous balloon angioplasty and endovascular stent placement are becoming common techniques intended to reduce the need for surgical bypass procedures that may be more expensive or have higher morbidity rates. Prophylactic antibiotics are not currently used before stent placement in most centers even when implanted via the femoral route. Infectious complications have been rare. In the case presented here an infected common iliac pseudoaneurysm occurred after percutaneous balloon angioplasty and stent placement. The literature is reviewed.

Transluminal extraction catheter for the treatment of diseased saphenous vein grafts: a multicenter experience

To evaluate the efficacy, safety, and long-term results of atherectomy using the Transluminal Extraction catheter (TEC), patients with diseased saphenous vein grafts were enrolled in a prospective nonrandomized trial. Patients were followed to hospital discharge for acute complications and underwent routine 6-mo reevaluation with repeat cardiac catheterization to assess restenosis. Atherectomy was performed on 650 graft lesions in 538 consecutive patients (male 81%; mean age 66 yr; range 37-81). Mean graft age was 8.3 yr; (range 0.3-20) with 85% of grafts > 3 yr of age. Complex lesion morphology included thrombus (28%), ulceration (13%), and eccentricity (50%). Lesion success was achieved in 606 lesions (93%) with clinical success in 479 patients (89%). Lesion success was achieved in 90% of thrombus containing lesions, 97% of ulcerated lesions, and 97% of grafts > 3 yr. Complications included nonfatal myocardial infarction in 4 (0.7%) of patients, emergency bypass surgery in 2 (0.41%), and in-hospital death in 17 patients (3.2%). Angiographic follow-up at 6 mo was obtained from 268 lesions in 227 patients. The overall lesion angiographic restenosis rate was 60%. TEC atherectomy can be performed in patients with diseased saphenous vein grafts with high primary success and low complication rates. It is suitable for use in aged grafts, particularly in the presence of thrombus and ulcerations, and may be superior to balloon angioplasty alone in this group of patients.

Comparison of three coronary stents: clinical and angiographic outcome after elective placement in 134 consecutive patients

One hundred and thirty-four consecutive patients undergoing elective coronary stenting were studied to assess the relative performance of Palmaz-Schatz (PS), Gianturco-Roubin (GR), and Wiktor (W) stents. Eighty-six percent of patients underwent follow-up angiography. Initial and follow-up angiograms were assessed by a central angiographic core laboratory. Attempts were made to place 81 Palmaz-Schatz (PS) stents, 21 Gianturco-Roubin (GR), and 32 Wiktor (W) stents. PS stents were less frequently successfully deployed (88% PS vs. 100% GR vs. 97% W; P = 0.03). The final percent stenosis was greater with the GR stent (32% GR vs. 14% PS vs. 19% W; P < 0.001). The restenosis rate was lower in the PS group (PS 48.2% vs. GR 66.7% and W 68.4%; P = 0.044). After accounting for the effect of prior restenosis (P = 0.005) and saphenous vein site (P = 0.006) in multivariate testing, lesion severity at follow-up was still less with the Palmaz-Schatz stent (P = 0.037).

Angiographic follow-up of patients after transluminal coronary extraction atherectomy

The transluminal coronary extraction-endarterectomy catheter (TEC) consists of a torquing tube with a distal, conical rotating blade. We successfully treated 26 patients (27 lesions) using this catheter with adjunctive balloon angioplasty. Twenty-five patients (26 lesions) had serial angiography before, 1 day after, and 3 months after the procedure. All 17 patients without restenosis 3 months after the procedure had angiography at 6 months. Restenosis, defined as > 50% diameter stenosis, was noted in nine lesions at 3 months (early restenosis) and in five lesions at 6 months (late restenosis). Between vessels with and without early restenosis, the percentage of diameter stenosis seen 1 day after the procedure and the luminal diameter were significantly different (38% +/- 14% vs 22% +/- 12%, respectively, p < 0.01; 2.3 vs 2.9 mm, p < 0.01, respectively). However, between vessels with and without late restenosis, these variables were not significantly different. The overall restenosis rate was 54% (native vessels 50%; grafts 80%). This observational study suggests that very early diameter narrowing seen 1 day after the procedure has greater contribution to early restenosis than to late restenosis after successful TEC atherectomy with adjunctive balloon angioplasty.

Subintimal versus intraluminal laser-assisted recanalization of occluded femoropopliteal arteries: one-year clinical and angiographic follow-up

PURPOSE

To compare the prolonged effect of subintimal versus intraluminal recanalization of occluded femoropopliteal arteries.

PATIENTS AND METHODS

Recanalization of an occluded femoropopliteal artery was attempted in 63 patients (51 men, 12 women; mean age, 63 years) with lifestyle-limiting claudication and at least one patent distal artery. After assessment of baseline clinical and angiographic variables, mechanical passage was first attempted with use of a laser catheter with a 2.2-mm- diameter hemispherical contact probe that was connected to a neodymium: yttrium-aluminum-garnet laser. In case of failure, the laser was activated at 1-second pulses of 15 W. In some cases additional guide-wire and catheter manipulations were used. Successful recanalization was followed by standard balloon dilation. An intense antithrombotic regimen was used.

RESULTS

The occluded artery could be entered in 62 of 63 patients. The catheter was assumed to have followed a subintimal course in 20 patients (group A) and an intraluminal course in 42 patients (group B). Successful recanalization was achieved in 17 patients (85%) of group A and in 36 (86%) of group B. No significant differences were found in clinical and angiographic follow-up measurements between the two groups. The angiographic cumulative primary patency rate (open vs closed) at 1 year was 93% +/- 6 in group A and 93% +/- 4 in group B. The cumulative restenosis/reocclusion-free patency rate was 63% +/- 13 and 65% +/- 9 for groups A and B, respectively. Median length of the original occlusion (8.0 cm in group A vs 4.5 cm in group B) was the only distinguishing baseline variable between the groups (P < .02) and was also the single independent predictor of recurrent flow limitation (P = .0017). Significant complications were distal embolization in three patients, followed by death in one patient and puncture site bleeding in two patients.

CONCLUSION

The 1-year clinical and angiographic results of assumed subintimal and intraluminal recanalization are comparable. Thus, a subintimal course per se should not be regarded as a failure of the procedure.

Dual-balloon progressive coronary dilatation catheter: design and initial clinical experience

As newer interventional devices continue to enter the marketplace, balloon angioplasty remains the standard by which all devices are judged with regard to both safety and efficacy. It has been observed that predilating a stenosis with a small balloon followed by dilatation with an optimally sized larger balloon creates a more controlled arterial injury, reduces complications, and thus improves success rates. Exchanging two balloons for each lesion, however, increases the complexity and cost of the procedure in addition to increasing the amount of time required and the amount of radiation exposure. Therefore an "over-the-wire" dual-balloon catheter was developed with a small distal balloon and a larger proximal balloon on a 2.9F shaft to allow progressive coronary dilatation with a single device, without necessitating a balloon catheter exchange. The device was used successfully in 45 of 47 patients (78 lesions). The two failures were related to an inability to cross the lesion in one and failure of the device in the other. Twenty-one patients (47%) underwent a multivessel procedure. There were 29 left anterior descending/diagonal, 17 circumflex/marginal, 20 right coronary artery/posterior descending artery, and 10 vein graft lesions. The device was successfully delivered in the native anatomy to 12 distal, 27 mid, and 27, proximal lesions of which nine were osteal, for a procedural success rate of 97%. The mean stenosis was reduced from 80.7 +/- 11.5% to 15.2 +/- 11.9%. There were no major dissections, only 9 (11.2%) minor dissections, and no myocardial infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial mapping with color flow duplex imaging of the lower extremities after excimer-laser-assisted angioplasty

The purpose of the present study was to evaluate the role of color flow duplex imaging (CFDI) in the follow-up of patients who have undergone excimer-laser-assisted angioplasty of peripheral arteries. Sixty-one patients (40 men and 21 women) were studied (mean age +/- SD sixty-three +/- nine years). All patients were affected by peripheral vascular disease and, for this reason, underwent percutaneous excimer-laser-assisted angioplasty. Digital angiography and CFDI were performed before the laser procedure. CFDI was repeated at months 1, 3, 6, 9, and 12 after the laser procedure, whereas angiography was repeated after twelve months. Common, superficial, and profunda femoral arteries and popliteal arteries were visualized in looking for the presence of lesions and occlusions, and spectral analysis of Doppler signals was recorded. After the initial success, claudication was reported again by 9 patients, 7 of whom showed total occlusions. All reocclusions were discovered by CFDI and confirmed by angiography; 3 of these 7 patients underwent a second laser procedure. The remaining 2 symptomatic patients showed patent vessels and did not undergo angiography. Another 9 patients redeveloped an occlusion, unsuspected from clinical history and symptoms. All the reocclusions, confirmed by angiography, were diagnosed by CFDI. The data show that CFDI provides an accurate noninvasive technique for following up patients after excimer laser angioplasty, allowing for asymptomatic reocclusions to be recognized and treated if necessary, and permitting symptoms not due to reocclusions to be properly identified, thus avoiding unnecessary angiography.

Clinical trial of percutaneous peripheral ultrasound angioplasty

OBJECTIVES

The purpose of this study was to present follow-up data as well as short-term results on a larger clinical series of patients undergoing ultrasound angioplasty.

BACKGROUND

Previous pilot studies have demonstrated the feasibility of peripheral arterial ultrasound angioplasty.

METHODS

We performed percutaneous ultrasound angioplasty on 50 arterial lesions in 45 patients. Our ultrasound ablation system had a frequency of 19.5 kHz. A fixed-wire probe with 2- or 3-mm ball tips and a 3-mm over-the-wire probe were used to treat 40 femoral, 7 popliteal and 3 tibioperoneal lesions. Seventeen (34%) of the lesions were calcific. Thirty (86%) of 35 occluded segments, 0.5 to 28 cm long (mean 6.2 +/- 5.7), were recanalized.

RESULTS

In the 45 patent arteries, the stenosis decreased from 94 +/- 10% to 55 +/- 23% after ultrasound angioplasty and to 12 +/- 8% after balloon angioplasty. Mechanical arterial dissections (n = 4) and perforations (n = 4) without clinical consequence occurred only with the fixed non-over-the-wire probes. No evidence of embolism or vasospasm was detected; in fact, vasodilation occurred. There were no clinical manifestations of acute reocclusion. At 24 h, ankle-brachial indexes increased by 0.23 +/- 0.21 (range -0.27 to 0.72). Six- to 12-month clinical and ankle-brachial index follow-up data for 35 patients treated with ultrasound and adjunctive balloon angioplasty were indicative of restenosis in 7 patients (20%).

CONCLUSIONS

Our findings indicate that percutaneous peripheral ultrasound angioplasty 1) is useful for recanalization of fibrous, calcific and thrombotic arterial occlusions; 2) reduces arterial stenoses; and 3) has clinical and ankle-brachial index data indicative of a restenosis rate of 20% at 6 to 12 months in a small cohort of patients. A larger randomized series of patients will need to be studied to assess the impact of ultrasound ablation on restenosis.

Intracoronary stent implantation: new approach using a monorail system and new large-lumen 7F catheters from the brachial route

In this brief report we describe a case of successful multivessel PTCA with intracoronary stent implantation using a new large-lumen 7F catheter from the left brachial approach. The application of this technique should be considered for intravascular stent implantation when anticoagulation ideally should not be interrupted or in anatomical situations limiting femoral vascular access.

Novel coronary interventional devices: an update

Interventional cardiologists today are overwhelmed by a hugh array of new high technology investigatory devices at their disposal for the treatment of coronary arterial obstructive disease. These include the various atherectomy and laser devices, developed and introduced into clinical practice with the promise and intent of solving the limitations of conventional balloon angioplasty, namely those of acute closure and restenosis. But as more experience and data are obtained from the application of these devices, it is becoming clear that the latter have generally not been able to accomplish what they were intended to do. Although the immediate success rates have been uniformly high, acute closure has persisted and restenosis remains unabated. Nevertheless, some of these new devices have shown some fairly encouraging results in specific clinical circumstances. The targeted use of these instruments may prove to be a step in the right direction. This article reviews the current state of the art and the potential utility of certain of these devices.

Disruption of a coronary stent during atherectomy for restenosis

Directional coronary atherectomy is being used in the treatment of atherosclerotic lesions in coronary vessels and vein grafts. This report describes the use of atherectomy for the treatment of restenosis of a coronary stent. The procedure was complicated by disruption of the stent which was snared by the atherectomy cutter.