Transluminal atherectomy for occlusive peripheral vascular disease

Peripheral atherectomy with the rotablator: a multicenter report. The Collaborative Rotablator Atherectomy Group (CRAG)

PURPOSE

Our purpose was to evaluate the efficacy and limitations of the Auth Rotablator, an atherectomy device recently approved by the U.S. Food and Drug Administration for general use in treating peripheral arterial occlusive lesions.

METHODS

Between August 1987 and December 1990, 72 patients from three medical centers (University of California, Los Angeles, Montefiore, and Stanford) underwent atherectomy with the Auth Rotablator in 79 limbs and 107 arteries: 2 iliac, 45 femoral, 29 popliteal, and 31 tibial. The average age among the 72 patients was 69 years (43 to 91 years), and 67% were men. Indications for atherectomy were claudication in 34 (43%), limb threat in 44 (56%), and asymptomatic in 1 (1%) case. Average ankle-brachial index was 0.47 (0 to 0.81). Average length of lesions was 9 cm (1 to 40 cm); 70 treated arterial segments were less than 10 cm and 37 were greater than 10 cm. All patients underwent arterial pulse examination, vascular laboratory Doppler measurement of ankle-brachial indexes, and arteriography before and after surgery and at follow-up intervals during a period of 15 to 41 months (mean 27 months).

RESULTS

Angiographic success (residual lumen < 25% stenosis) was achieved in 70 (89%) of 79 limbs and 82 (77%) of 107 arteries: iliac 1 (50%) of 2, femoral 38 (84%) of 45, popliteal 24 (83%) of 29, and tibial 19 (61%) of 31. In-hospital clinical and hemodynamic success was achieved in 61 (77%) of 79 limbs. The cumulative primary patency rate was 47% at 6 months, 31% at 12 months, and 18.6% at 24 months. Complications included hemoglobinuria in 10 cases (13%), emboli in eight cases (10%), dissection in five cases (6%), perforation in three cases (4%), hematoma in four cases (5%), and infection in one case (1%). There were nine early thromboses (11%) and two device-related amputations (2.5%).

CONCLUSION

Peripheral atherectomy with the Auth Rotablator currently has limited application because of frequent early thromboembolic complications and poor late patency rates. Atherectomy is not generally recommended for treating peripheral arterial occlusive lesions until these problems with early thromboemboli, occlusions, and late restenoses are solved.

Corticosteroid agents inhibit proliferation of smooth muscle cells from human atherosclerotic arteries in vitro

We studied the in vitro effect of steroid agents on smooth muscle cells from human atherosclerotic arteries. Recent advances in the understanding of the biology of restenosis indicate that restenosis is predominantly caused by a multifactorial stimulation of smooth muscle cell proliferation. Primary stenosing plaque material of 24 patients (aged 63 +/- 14 years) and restenosing plaque material of 7 patients (aged 65 +/- 9 years) was selectively extracted from femoral arteries by the Simpson atherectomy device. Cells were isolated by enzymatic disaggregation and identified as smooth muscle cells by positive reaction with smooth muscle alpha-actin. The steroid agents prednisolone (0.0075-750 micrograms/ml), hydrocortisone (0.0125-1250 micrograms/ml), and dexamethasone (0.0004-40 micrograms/ml) were added to the cultures. Six days after seeding the cells were trypsinized and the cell number was measured by a cell counter. All three steroid agents exhibited a significant antiproliferative effect on smooth muscle cell proliferation. At high concentrations of hydrocortisone, cytoskeletal elements of smooth muscle cells such as actin, microtubules, and vimentin, were largely altered. Our data indicate that the proliferation of smooth muscle cells from human atherosclerotic arteries in vitro can be inhibited by steroid agents and thus may open the way for local post-angioplasty treatment strategies.

Proliferation and extracellular matrix synthesis of smooth muscle cells cultured from human coronary atherosclerotic and restenotic lesions

OBJECTIVES

The purpose of this study was to examine the proliferative capacity and extracellular matrix synthesis of human coronary plaque cells in vitro.

BACKGROUND

Common to both primary atherosclerosis and restenosis are vascular smooth muscle cell proliferation and production of extracellular matrix proteins. The applicability to humans of experimental animal models of these processes has been questioned.

METHODS

Primary atherosclerotic and restenotic lesions were excised by percutaneous directional coronary atherectomy in 93 patients. Smooth muscle cells were cultivated by an explant technique and identified by their morphology in culture, ultrastructural features under electron microscopy and immunostaining using monoclonal antibodies to smooth muscle cell alpha-actin. Proliferation in secondary culture was assessed with growth curves and the synthesis of collagen and sulfated glycosaminoglycans by the incorporation of 3H-proline and 35S-sulfate, respectively. These studies were also performed in cells derived from human umbilical artery media.

RESULTS

Success rates for primary (45%) and secondary (12%) culture of coronary cells were not influenced by clinical variables or lesion category. Primary culture success was improved by the presence of organized thrombus in the plaque and in relation to increased maximal cell density of the atherectomy specimen. Restenotic cells displayed more rapid growth than did cells of primary atherosclerotic origin, which grew in a manner similar to that of umbilical artery cells. Mean calculated population-doubling times for the three cell groups were 52 h (95% confidence interval [CI] 48 to 58 h), 71 h (95% CI 62 to 83 h) and 74 h (95% CI 65 to 84 h), respectively. Restenotic and primary atherosclerotic cells did not differ in the synthesis of collagen ([mean +/- SEM] 0.034 +/- 0.004 vs. 0.033 +/- 0.004 nmol isotope.microgram protein-1, p = NS) or sulfated glycosaminoglycans (11.47 +/- 1.07 vs. 15.37 +/- 3.10 nmol isotope.microgram protein-1, p = NS), but the coronary cells synthesized significantly more collagen and sulfated glycosaminoglycans than did umbilical artery cells (0.019 +/- 0.004 and 5.43 +/- 1.00 nmol isotope.microgram protein-1, respectively, both p < 0.05).

CONCLUSIONS

These data indicate that increased smooth muscle cell proliferation contributes to coronary restenosis in humans and support the concept that the extracellular matrix synthesis of adult smooth muscle cells is important to lesion formation.

Directional atherectomy with the Omnicath: a unique new catheter system

Omnicath is a directional atherectomy catheter that employs deflecting nontraumatizing wires to anchor the cutting window at the atherectomy site. This anchoring system regulates the depth of cut and provides directional control and distal perfusion. The system continuously removes debris through a suction port from the operative site. To demonstrate the performance of the device, the Omnicath was tested in the external iliac arteries of ten atherosclerotic Hanford miniature swine in which concentric and eccentric lesions were induced. Five animals were sacrificed 3 days after atherectomy; the remaining five animals were sacrificed 6 weeks after the procedure. The acute histology demonstrates depth of cuts varying from partial plaque removal to near full thickness removal of the arterial wall. Histologic sections of the 6 week follow-up group demonstrated minimal healing response. The anchoring wires did not induce either acute injury or neointimal proliferation in the 6 week follow-up period. In conclusion, the Omnicath permits effective and safe atherectomy in this investigative model.

Qualitative and quantitative contrasts in the mechanisms of lumen enlargement by coronary balloon angioplasty and directional coronary atherectomy

OBJECTIVES

This study was designed to define and contrast the mechanisms of lumen enlargement from coronary balloon angioplasty and directional coronary atherectomy using intracoronary ultrasound imaging in vivo.

BACKGROUND

The mechanisms of lumen enlargement produced by percutaneous transluminal coronary balloon angioplasty and directional coronary atherectomy are not known because the coronary artery wall has not previously been studied both before and after dilation.

METHODS

We used intracoronary ultrasound to quantitate coronary lumen, vessel and plaque area both before and immediately after successful coronary angioplasty (n = 30) and directional coronary atherectomy (n = 25) at the site of most severe stenosis.

RESULTS

Angioplasty increased lumen area by 2.80 +/- 0.25 mm2 (mean +/- SE, p < 0.0001). Eighty-one percent of this lumen gain resulted from an increase in vessel area and the remaining 19% from a reduction in plaque area. Lumen gain of individual lesions was separated into three groups: 67% had an increase in vessel area (vessel expansion), 13% had a decrease in plaque area and 20% had a combination of both. In contrast, vessel expansion contributed only 22% of the lumen gain with directional coronary atherectomy, with the majority (78%) of increase in lumen size coming from a reduction in plaque area. Directional coronary atherectomy increased lumen area from 2.36 +/- 0.05 to 7.00 +/- 0.28 mm2 (p < 0.0001). Plaque reduction was the sole mechanism in 60% of lesions, vessel expansion was the sole mechanism in 12% and a combination of both mechanisms occurred in 28%. Lumen enlargement of eccentric lesions treated with directional coronary atherectomy was more commonly associated with plaque reduction (p < 0.02), whereas eccentricity did not affect the mechanism of lumen enlargement with coronary angioplasty.

CONCLUSIONS

This is the first study to systematically examine the coronary artery wall in vivo at the site of a severe stenosis both before and after catheter-based interventions in humans. Lumen enlargement from coronary angioplasty occurs predominantly from vessel expansion or stretching, although a reduction in plaque area contributes to the lumen gain in many patients and is the sole mechanism in a few. Lumen gain from directional coronary atherectomy is predominantly from reduction in plaque area (probably owing to tissue removal), although vessel stretching (balloon effect) occurs and is the sole mechanism in a small minority of vessels. Plaque reduction is more common in directional coronary atherectomy of eccentric lesions.

Specific indications for directional coronary atherectomy: origin left anterior descending coronary artery and bifurcation lesions

Directional coronary atherectomy is emerging as the treatment of choice for many patients with significant lesions involving left anterior descending coronary artery origin or vessel bifurcations. It offers the potential advantages of safe, reliable, and predictable treatment of these selected complex lesions. Future modifications and improvements in the design of the atherectomy device (AtheroCath; Devices for Vascular Intervention, Redwood City, CA) may further expand its application to smaller and calcified vessels.

Histologic analysis of directional coronary atherectomy samples. A review of findings and their clinical relevance

Histologic analysis of atherectomy samples from > 400 patients who received directional coronary atherectomy at 3 separate institutions disclosed 2 major categories of tissue: atherosclerotic plaque (with or without thrombus) and intimal proliferation (hyperplasia, with or without thrombus). The predominant tissue type in atherectomy samples from native, primary, or de novo coronary artery stenoses was atherosclerotic plaque. The predominant tissue type in atherectomy samples from restenosis lesions (prior balloon angioplasty, atherectomy, or both) was intimal proliferation with variable amounts of atherosclerotic plaques (with or without thrombus). Deep vessel wall components (media, adventitia) were identified at varying frequencies. The clinical relevance of atherectomy tissue is reviewed.

Experience with directional coronary atherectomy since pre-market approval

Directional coronary atherectomy (DCA) received Food and Drug Administration (FDA) Pre-Market Approval in September 1990 and was then released through formal training certification of physicians at each new site. Procedure volume has increased dramatically since approval, with > 17,000 DCA procedures performed in 1991 and a cumulative total of > 33,000 procedures by mid-1992, at > 670 centers in the United States. Clinical application and results since approval have generally been similar to preapproval multicenter investigational results. Comparison of pre- and postapproval usage at the Medical College of Virginia shows similar baseline characteristics and indications, although recent patients show a higher proportion of "salvage" DCA for failed or suboptimal angioplasty (6% vs 14%) or DCA in combination with multidevice multiple vessel intervention (30% vs 38%). Overall results in 300 patients and 345 procedures included procedural success in 95%, clinical success in 94%, with major complications in 4.6% (including urgent bypass surgery in 3.8%, Q wave myocardial infarction in 1.7%, and hospital mortality in 0.3%). Results before and after FDA approval were similar for procedural success (94% vs 96%), clinical success rate (94% vs 94%), and major complications (5.5% vs 4.4%). There was a trend toward lower urgent surgery rate (5.4% vs 3.3%) in the more recent experience. In addition to its established efficacy for highly eccentric lesions, newer applications for which DCA is being used following FDA approval include treatment of saphenous vein grafts, thrombus-associated lesions, aorto-ostial lesions, failed or suboptimal percutaneous transluminal coronary angioplasty result, bifurcation lesions, and use as part of multivessel intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Economics of elective coronary revascularization. Comparison of costs and charges for conventional angioplasty, directional atherectomy, stenting and bypass surgery

OBJECTIVES

This study was designed to evaluate more closely the true in-hospital costs of elective revascularization by directional coronary atherectomy and intracoronary stenting and to compare these costs with those of the traditional revascularization alternatives (i.e., conventional balloon angioplasty and coronary artery bypass surgery).

BACKGROUND

Previous studies have suggested that total hospital charges for directional coronary atherectomy or intracoronary stenting are significantly higher than those for conventional angioplasty. However, hospital charges do not necessarily reflect true economic costs, and their use may provide misleading data with regard to cost-effectiveness.

METHODS

We analyzed in-hospital charges from the itemized hospital accounts of 300 patients undergoing elective angioplasty, directional atherectomy, Palmaz-Schatz coronary stenting or bypass surgery between January 1, 1990 and December 31, 1991. Costs were then derived by adjusting itemized patient accounts for department-specific cost/charge ratios. Catheterization laboratory costs were based on actual resource consumption, and daily room costs were adjusted for the intensity of nursing services provided.

RESULTS

Length of hospital stay was similar for atherectomy (2.3 +/- 1.5 days) and conventional angioplasty (2.6 +/- 1.7 days) but significantly longer for stenting (5.5 +/- 2.6 days, p < 0.05). Total costs were also significantly higher for coronary stenting ($7,878 +/- $3,270, median $6,699, p < 0.05) than for angioplasty ($5,396 +/- $2,829, median $4,753) or atherectomy ($5,726 +/- $2,716, median $4,986). However, length of stay, resource consumption (laboratory and radiologic testing, drugs, blood products, for example) and total costs for bypass surgery were still greater than for any of the percutaneous interventional procedures.

CONCLUSIONS

In contrast to previous studies utilizing only hospital charges, the in-hospital costs of angioplasty and directional coronary atherectomy were similar. Although the cost of coronary stenting was approximately $2,500 higher than that of conventional angioplasty, the magnitude of this difference was smaller than the $6,300 increment previously suggested on the basis of analysis of hospital charges. These findings reflect the inherent discrepancies between cost-based and charge-based methodologies and may have important implications for future studies evaluating the relative cost-effectiveness of newer coronary interventions.

Detailed angiographic analysis of high-speed mechanical rotational atherectomy in human coronary arteries

BACKGROUND

Several types of atherectomy devices have been developed recently for treatment of patients with ischemic heart disease.

METHODS AND RESULTS

Mechanical rotational atherectomy (MRA) using a high-speed rotational burr (Rotablator) was performed on 116 lesions in 104 patients. MRA alone was performed in 27 lesions (23%), and conventional balloon angioplasty (PTCA) was performed after MRA in 89 lesions (77%). Diameter stenosis decreased from 70 +/- 13% before MRA to 54 +/- 23% after MRA, and the final diameter stenosis (after MRA alone or with adjunctive PTCA) was 30 +/- 20% (P < .001). Minimal lumen diameter increased from 1.0 +/- 0.5 mm before MRA to 1.4 +/- 0.7 mm after MRA, and the final minimal lumen diameter was 2.3 +/- 0.7 mm (P < .001). MRA resulted in a decrease in diameter stenosis of 20% or more in 44% of lesions, and the final diameter stenosis (after MRA alone or after PTCA) was less than 50% in 75% of lesions. Considering the small diameter of available burrs, the magnitude of lumen enlargement was equal to 91% of the burr diameter, and only 9% of the burr diameter was "lost" due to elastic recoil or spasm. These angiographic results were obtained despite the presence of complex lesion morphology, including the presence of calcification in 17% of lesions and ostial location in 26% of lesions. Significant angiographic complications included abrupt closure (13 lesions, 11.2%), no reflow (8 lesions, 7%), severe coronary vasospasm (16 lesions, 13.8%), and guide wire fracture (3 lesions, 2.7%). There were no coronary artery perforations. Adjunctive therapy, including salvage PTCA, thrombolytic agents, and vasodilators, was successful in treating angiographic complications in 42 of 49 lesions (86%). Clinical complications included Q-wave myocardial infarction (5 patients, 4.8%), non-Q-wave myocardial infarction (3 patients, 2.9%), femoral vascular injury requiring surgery (3 patients, 2.9%) or blood transfusion (8 patients, 7.7%), abrupt closure requiring emergency bypass graft surgery (2 patients, 1.9%), and in-hospital death (1 patient, 1.0%). Angiographic follow-up (mean follow-up interval, 5.0 +/- 2.0 months) was available in 84% of successfully treated patients and revealed a restenosis rate of 51%, defined as a residual diameter stenosis of more than 50%. There was no significant difference in restenosis rates between de novo lesions (50%) and restenosis (54%) lesions.

CONCLUSIONS

These data suggest that for the treatment of most coronary stenoses, PTCA is required after MRA to achieve satisfactory lumen enlargement or to salvage complications. Angiographic complications appear to be more common after MRA, and salvage PTCA often is required to manage these device-induced complications. The combination of MRA and PTCA does not prevent restenosis.

Catheter atherectomy of intimal fibroplasia of the common iliac artery

An 18-year-old woman presented with renovascular hypertension and left lower extremity claudication. Aorto-iliac angiography showed stenotic lesions in the left renal artery and the left common iliac artery. For uncontrolled hypertension, nephrectomy was performed and histopathology of the renal artery showed intimal fibroplasia, an uncommon type of fibromuscular dysplasia. The left common iliac artery lesions were treated with directional atherectomy, which produced excellent immediate angiographic and symptomatic improvement.

Management of superficial femoral artery occlusive disease

The prevalence of intermittent claudication in men aged 55-74 years is 4.5 per cent and a common cause of such claudication is superficial femoral artery (SFA) occlusive disease. The preferred management of patients with this condition remains a subject of discussion. Therapeutic options range from conservative treatment to endovascular intervention and surgical bypass or endarterectomy. Conservative therapy is the primary treatment of choice. However, if this fails and an endovascular technique is chosen, percutaneous transluminal angioplasty (PTA) is the best option; other endovascular methods have failed to achieve higher rates of technical success or patency. PTA should be considered only for short lesions (< or = 10 cm). The usual surgical option for SFA occlusive disease is femoropopliteal bypass using autogenous vein, which has an expected 5-year patency rate of 56-76 per cent. Patency rates decrease if other types of graft are used. An alternative to vein bypass is endarterectomy, with an expected 5-year patency rate of 35-71 per cent. A multicentre randomized trial should be conducted to determine the optimal management of claudication caused by SFA occlusive disease.

Successful directional atherectomy of eccentric renal artery stenosis using the Simpson directional coronary atherocath as a primary therapy

A 67-yr-old female patient with accelerated hypertension, severe peripheral vascular disease, diabetes mellitus, and coronary artery disease had an abnormal renal scan, renal angiogram, and renal vein renin determination with lateralization to the left kidney. Angiography demonstrated a very tight, eccentric plaque obstructing the left renal artery of approximately 99%. Because of the anatomy of the plaque, balloon dilatation was deemed inadvisable. Subsequently, a Simpson 7F graft DCA atherocath through a four-curved 10F right bypass graft guiding catheter was used to successfully debulk the left renal artery. After debulking, the artery was dilated with a 5 mm Meditech balloon on a wire through a Cobra guiding catheter. The patient's blood pressure responded immediately and there were no complications. A large amount of atherosclerotic plaque was removed from the renal artery.

Amputation of the fine guidewire tip during atherectomy using the Simpson "over-the-wire" peripheral atherectomy catheter

After successful treatment of a localized eccentric atheromatous deposit in the distal superficial femoral artery using the Simpson "over-the-wire" atherectomy catheter, a short segment of guidewire tip was noted in the proximal peroneal artery. A digital angiogram of the distal vessels showed satisfactory run-off. There were no immediate clinical sequelae and none after 2 months follow-up.

Peripheral angioplasty balloon technology

Changes in balloon and catheter technology have led to the development of smaller, more flexible, and less traumatic balloon dilatation systems. The physical principles that govern balloon angioplasty and the current status of balloon materials and catheter designs will be reviewed. A compilation of various angioplasty catheters is also summarized.

Relation between activated smooth-muscle cells in coronary-artery lesions and restenosis after atherectomy

BACKGROUND

Neointimal proliferation leading to restenosis frequently develops after coronary angioplasty. This process is associated with a change in vascular smooth-muscle cells from a contractile (quiescent) phenotype to a synthetic or proliferating (activated) one. We investigated whether the presence of activated smooth-muscle cells in coronary lesions at the time of coronary atherectomy predisposes patients to subsequent restenosis.

METHODS

We used in situ hybridization to study the expression of messenger RNA in coronary-atherectomy specimens from 20 patients. Plaque material was hybridized with a probe for the B isoform of human nonmuscle myosin heavy chain, a major nonmuscle myosin isoform in activated, but not quiescent, smooth-muscle cells. Angiographic follow-up data were obtained a mean (+/- SD) of 174 +/- 54 days after atherectomy in 16 of the 20 patients, and the extent of recurrent luminal narrowing was analyzed quantitatively. The presence of restenosis was assessed by exercise thallium scintigraphy in the other four patients.

RESULTS

Atherectomy specimens from 10 of the 20 patients showed hybridization with the probe, defined as the clustering of more than 20 silver grains per cell nucleus in more than 10 nuclei in five high-power fields (x250); specimens from the other 10 patients showed no such hybridization. At follow-up, restenosis had developed in 8 of the 10 patients with positive hybridization results, but was absent in 9 of the 10 patients with negative results (P = 0.007). The degree of late loss in luminal diameter was significantly higher in patients with positive hybridization results than in those with negative results (ratio of late loss to immediate gain after atherectomy, 0.76 +/- 0.3 vs. 0.36 +/- 0.3; P < 0.001).

CONCLUSIONS

We conclude that the expression of the B isoform of nonmuscle myosin heavy chain is increased in some coronary atherosclerotic plaques and that this increase in expression identifies a group of lesions at high risk for restenosis after atherectomy.

Biological risk factors for restenosis after percutaneous transluminal coronary angioplasty

In an attempt to discern biological (such as thrombotic or fibrinolytic) risk factors in patients developing restenosis after percutaneous transluminal coronary angioplasty, the following factors were measured prior to angiography in a population of 23 patients (20 men, 3 women, mean age 57 +/- 5 yr) treated by a successful angioplasty (gain > 20% and residual stenosis < 50%) for stable angina pectoris and who had a routine angiographic restudy. The following factors were thus assessed: lipid factors: cholesterol, triglycerides, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B; coagulation factors: fibrinogen, antithrombin III, fibrinopeptide A, factor VIII coagulant, factor VIII antigen, protein C; factors of physiological fibrinolysis: plasminogen, alpha 2-antiplasmin, tissue plasminogen activator and euglobulin clot lysis time before and after venous occlusion, plasminogen activator inhibitor before venous occlusion; and factors of platelet release: beta-thromboglobulin, platelet factor 4. Also studied were clinical characteristics: age, gender, diabetes, hypertension, smoking habits, previous myocardial infarction; angiographic data: global extent of coronary artery disease, location of the stenosis in a bend or branch point, complexity of the lesion, initial and residual stenosis and treatment during follow-up. The coronary angiograms were analyzed by a computer-assisted method with automatic edge detection. On angiographic criteria, 6 patients (restenosis group) were judged to have developed a restenosis (30% decrease in diameter and/or return to a 50% stenosis). The other 17 patients (those without restenosis) were considered to have a persistent success. Apart from age (group without restenosis: 55 +/- 6; restenosis group 61 +/- 5, p < 0.04), there were no differences in clinical, angiographic or treatment variables. There were no differences in lipid factors, but significant differences were observed in hemostatic variables: fibrinogen (without restenosis: 3.18 +/- 0.83; restenosis: 3.83 +/- 0.51 milligrams, p = 0.05), tissue plasminogen activator before venous occlusion (without restenosis: 10.9 +/- 26.8; restenosis: 232.5 +/- 371.2 IU, p < 0.04), euglobulin clot lysis time after venous occlusion (without restenosis: 176.5 +/- 100.5; restenosis: 78.6 +/- 40.2 min, p < 0.05) and for marker of the platelet release: platelet factor 4 (without restenosis: 10.8 +/- 7.9; restenosis: 20.5 +/- 7.5 ng/l, p < 0.04). These findings indicate that patients developing restenosis after coronary angioplasty tend to have an imbalance in the prothrombotic-antithrombotic equilibrium prior to the procedure.

Long-term results of directional coronary atherectomy: predictors of restenosis

OBJECTIVES

This study was performed to obtain better understanding of the long-term clinical efficacy of directional coronary atherectomy.

BACKGROUND

Although this procedure yields favorable acute results, its acceptance has been limited by the perception that late results (that is, freedom from restenosis) are no better than those of conventional angioplasty.

METHODS

A total of 225 atherectomies performed in 190 patients between August 1988 and July 1991 were examined. Minimal lumen diameter of the treated segments was measured on angiograms obtained before, after and 6 months after intervention.

RESULTS

Although most lesions (97%) had one or more characteristics predictive of unfavorable short- or long-term results after conventional angioplasty, atherectomy was successful in 205 lesions (91%) with a mean residual stenosis of 7 +/- 16%. After subsequent balloon angioplasty in 16 unsuccessful atherectomy attempts, procedural success was 98%. There were no deaths or Q wave myocardial infarctions, and one patient (0.5%) underwent emergency bypass surgery. Six-month angiographic follow-up was obtained in 77% of the eligible patients. The overall angiographic restenosis rate was 32%. Predictors of a lower restenosis rate included a postprocedure lumen diameter > 3 mm (24% vs. 39%, p = 0.047), serum cholesterol < or = 200 mg/dl (18% vs. 40%, p = 0.018) and recent myocardial infarction (16% vs. 37%, p = 0.034). Life-table analysis showed a 2% mortality rate and a 26% incidence of other events (myocardial infarction, repeat revascularization) within the 1st year. The annual 5% mortality rate and 7% incidence of other events during years 2 and 3 were related in large part to the existence or progression of disease at other locations.

CONCLUSIONS

Six-month angiographic follow-up of patients who underwent directional coronary atherectomy during the 1st 3 years of our experience shows an overall restenosis rate of 32%, with lower rates in patients with a postatherectomy lumen diameter > or = 3 mm, cholesterol level < or = 200 mg/dl or a recent myocardial infarction. Few if any events relating to the site of atherectomy developed after the 1st year of follow-up.

Clinical, hemodynamic, electrocardiographic and mechanical events during nonocclusive, coronary atherectomy and comparison with balloon angioplasty

The periprocedural events and myocardial function during nonocclusive coronary atherectomy by Rotablator or transluminal extraction catheter (TEC) may differ from events during balloon angioplasty. This may have important clinical consequences and needs to be defined further. Therefore, 17 patients undergoing Rotablator and 18 undergoing TEC atherectomy were assessed by clinical, hemodynamic and electrocardiographic monitoring and simultaneous transesophageal echocardiography. The findings were compared with similar parameters during subsequent balloon angioplasty performed in 16 of 17 patients undergoing Rotablator and 14 of 18 undergoing TEC atherectomy. Chest pain occurred more frequently during balloon inflation than during either atherectomy (p less than 0.02), whereas ST-segment and T-wave electrocardiographic changes were equally frequent. Transient second- or third-degree atrioventricular block occurred in 6 patients during Rotablator but in none during TEC atherectomy or balloon inflation (p less than 0.01 for each). Hemodynamic parameters and global left ventricular function remained unchanged during atherectomy. Regional myocardial function in the distribution of the target coronary artery, assessed by a wall motion score, was not affected during Rotablator, but deteriorated slightly during TEC atherectomy and more significantly during balloon inflation (score from 0.3 +/- 0.5 to 1.0 +/- 0.7 during TEC and 2.0 +/- 0.6 during balloon inflation, p less than 0.005 for both). Thus, chest pain is infrequent, whereas hemodynamics and global left ventricular function are preserved during Rotablator and TEC atherectomy. Transient atrioventricular block during Rotablator and regional myocardial dysfunction during TEC atherectomy may occur without significant consequences. These data suggest that these techniques may be preferable to balloon angioplasty for preserving intraprocedural left ventricular function.

Options for percutaneous coronary and peripheral revascularization

Angioplasty has become an established treatment for both coronary and peripheral atherosclerosis, and a number of new techniques and devices promise to improve the results of percutaneous intervention during the coming decades. It is likely that balloon angioplasty will remain the percutaneous treatment of choice for both coronary and peripheral intervention; however, we look with hope toward the development of new devices that will expand the role of percutaneous angioplasty and improve the long-term success of these procedures. As technical expertise grows with the new procedures, prospective randomized trials comparing them with standard PTCA will be required to enable physicians to judge their clinical utility.

Efficacy of directional coronary atherectomy in cases unsuitable for percutaneous transluminal coronary angioplasty (PTCA) and after unsuccessful PTCA

Directional coronary atherectomy (DCA) was used in 10 female and 50 male patients with an average age of 58 years. They were categorized into three different groups depending on the indications for atherectomy. Group 1 included all patients who had atherectomy as their primary intervention (n = 20) because they were assumed to be unsuitable for percutaneous transluminal coronary angioplasty (PTCA). Group 2 consisted of patients in whom DCA was used after failed balloon dilatation with unsuccessful but uneventful treatment (n = 17). Group 3 (n = 23) included patients in whom DCA was performed as a "rescue" or "bailout" procedure after unsuccessful PTCA resulting in critical ischemia (ECG changes, chest pain, hypotension, and shock). The target lesions were located in the left main artery in two, left anterior descending artery in 43, right coronary artery in 15, and aortocoronary venous bypass in five. The mean length of the lesions was 8 mm (2 to 25 mm). The overall success rate for 65 lesions was 92%. The mean stenosis was reduced from 87 +/- 12% to 19 +/- 17% in patients with primary success. Presently available follow-up angiograms (30) showed six restenoses. Major complications occurred in seven patients (myocardial infarction in two and coronary artery bypass graft surgery within 24 hours in five); there were no deaths. Our results show that DCA is a safe and effective technique that can extend the use of percutaneous procedures and provide a promising nonsurgical option in cases of unsuccessful PTCA.

Status of peripheral atherectomy

So far, all atherectomy devices have failed to reduce the restenosis rate of standard balloon angioplasty. Despite actual removal, debulking, and even polishing of the atherosclerotic intima, the arterial wall trauma invariably incites intimal hyperplasia. Until the problem of restenosis can be solved, atherectomy will be limited to those instances when balloon angioplasty is ineffective or contraindicated. Each device has its own peculiarities. We prefer to use the Simpson catheter for eccentric lesions in the iliofemoral or femoropopliteal regions, the Auth Rotablator for short lesions in the infrageniculate vessels, and the TEC for longer lesions in the femoropopliteal regions. Adjunctive balloon angioplasty may or may not be required. Ahn and Moore have illustrated specific clinical strategies for peripheral atherectomy.

In vivo assessment of vascular pathology resulting from laser irradiation. Analysis of 23 patients studied by directional atherectomy immediately after laser angioplasty

BACKGROUND

The pathological consequences of cardiovascular laser irradiation have been studied extensively in vitro. Previous in vivo studies of laser-induced injury have included analyses of acute and/or chronic findings in experimental animals. Little information, however, is available regarding the acute effects of laser irradiation of human vascular tissues in vivo.

METHODS AND RESULTS

To determine the acute pathology resulting from laser irradiation of human vascular tissue in vivo, specimens retrieved from 23 patients by directional atherectomy immediately after laser angioplasty (19 peripheral and four coronary) were examined by light microscopy. Of the 23 patients, three (13.0%) were treated with a metal-capped ("hot-tip") fiber coupled to a continuous-wave neodymium:yttrium-aluminum-garnet (Nd:YAG) laser using up to 18 W power and 18-305 seconds of cumulative exposure time; in all three patients (100%), thermal injury, including frank charring several cell layers thick, was seen along the luminal borders of the atherectomy specimen. In eight of the 23 patients (34.5%), laser angioplasty was performed using a 250-microseconds holmium:YAG laser at fluences up to 2,300 mJ/mm2, a repetition rate of 5 Hz, and 25-200 seconds of cumulative exposure; in seven of eight patients (85.5%), the atherectomy specimen showed signs of vacuolar injury consisting of central and satellite Alcian-blue-negative vacuoles. In two patients (25.0%), there was a "smudged" or "shredded" edge, whereas in one patient, frank signs of thermal injury were observed. Finally, in 12 of the 23 patients (52.2%), laser angioplasty was performed using a 120-nsec excimer laser at fluences up to 60 mJ/mm2, a repetition rate of 25 Hz, and a cumulative exposure time of 21-315 seconds. Pathological findings among these 12 patients were limited to nine patients (75%) in whom a weakly basophilic, smudged, and/or shredded appearance approximately one cell layer thick was observed along the luminal border of the atherectomy specimen and two patients (16.7%) with small foci of vacuolar injury. None of the atherectomy specimens retrieved after excimer laser angioplasty disclosed signs of thermal injury.

CONCLUSIONS

These findings document that acute pathological alterations resulting from in vivo laser angioplasty are variable, depending on the laser source used, and are similar to that predicted by experimental studies performed previously in vitro. The prognostic implications of these varying pathological features remain to be clarified.

Intraoperative peripheral rotary atherectomy: early and late clinical results

Early and late clinical results of intraoperative peripheral atherectomy using the Auth Rotablator are analyzed. Twenty patients (15 males and 5 females age 39-89 years, mean 70 years) underwent 25 atherectomy procedures for peripheral arterial occlusive disease from August 1987 to October 1989. All patients underwent serial history, physical exam, and Doppler pressure measurements preoperatively and then postoperatively at 24 hours, one week, one month, and six months during a follow-up period of 15 to 41 months, mean 27 months. Preoperative and intraoperative completion follow-up arteriography was done in all cases and follow-up arteriography in 19 of 25 cases. Initial arteriographic success was achieved in 23/25 (92%) cases and in 39/41 (93%) arterial segments (superficial femoral artery 12/13, popliteal 14/15, tibial 12/13, profunda-femoral 1/1). Complications included intimal dissection (1), equipment breakage (2), minor emboli (3), major emboli with thigh skin loss (1), transient hemoglobinuria (4), wound hematoma (1), wound infection (1), and limb loss (1). Early thrombosis occurred in five cases to give an in-hospital success rate of 18/25 (72%). Primary patency was 66% at six months but only 12% at two years. Rotary atherectomy effectively recanalizes femoral, popliteal and tibial arteries. However, early thromboembolic complications occurred frequently, and the two year patency was dismal. Rotary atherectomy is not recommended for general use until problems of thromboemboli and intimal hyperplasia are solved.

Histologic findings in specimens obtained by percutaneous directional coronary atherectomy

Percutaneous directional coronary atherectomy is a second-generation, catheter-based technique for the treatment of coronary artery disease that provides a unique opportunity to study tissue obtained from coronary artery stenoses. We reviewed the histologic findings in 131 coronary atherectomy specimens from 116 patients, including 79 primary lesions and 52 restenosis lesions that developed after a prior coronary intervention. Although atherosclerotic plaque was seen in 95% of cases, an important observation was the finding of deep arterial wall components in the majority of patients, including media in 61% and adventitia in 31%. Despite the relatively common finding of deep wall components, this was not associated with acute clinical complications. Intimal hyperplasia was seen in 64% of cases, including 96% of restenosis lesions. However, intimal hyperplasia was also seen in 45% of primary lesions. The intimal hyperplasia in primary and restenosis lesions was histologically identical and was characterized by cells that showed staining for vimentin and muscle-specific actin, consistent with a myogenous and/or myofibroblastic phenotype. Restenosis was seen in 29 of 94 lesions (31%) with angiographic follow-up an average of 6.3 months after atherectomy. The risk of restenosis was not significantly related to the vessel treated, the nature of the lesion treated (ie, primary v restenosis lesion), or any of the histologic features evaluated. In conclusion, (1) deep arterial wall components are commonly observed in coronary atherectomy specimens without acute complications and (2) intimal hyperplasia is a sensitive, but not specific, marker for restenosis lesions.

Recurrence of stenoses following balloon angioplasty and Simpson atherectomy of the femoro-popliteal segment. A randomised comparative 1-year follow-up study using colour flow duplex

The results of balloon angioplasty (BA) and atherectomy (AT) with the Simpson atherocath, were compared in a randomised prospective study. Thirty-one patients were randomised to one of these methods for the treatment of symptomatic stenotic or occlusive lesions in the superficial femoral and popliteal arteries. One patient died after randomisation but before the procedure, thus 30 patients were available for analysis. All patients had intermittent claudication and BA was used in 14 and AT in 16 limbs. A surveillance protocol included colour flow duplex scanning of the femoro-popliteal arteries after 6 weeks and then at 3-monthly intervals during the 1st year and every 6 months thereafter. The average duration of follow-up was 9.7 months. For confirmation intra-arterial digital subtraction angiography (DSA) was performed in all patients at 1 year following the intervention, when clinical symptoms occurred or when colour flow duplex indicated greater than 49% restenosis. Three small dissections were the only postoperative complications and residual stenoses greater than 20% diameter reduction (DR) were observed in two patients following BA and in two after AT. Improvement of clinical category according to the "Standards for evaluating results of interventional therapy for peripheral vascular disease" occurred in 13 of 14 BA patients and in 15 of 16 AT patients. Follow-up results were expressed as cumulative patency and clinical success. Endpoints for patency were recurrence of the stenosis at the treated segment or new lesions in different segments and endpoints for clinical success were a drop in clinical category (symptoms, ankle pressure indices and post-exercise ankle pressures). One-year patency (no restenosis greater than 49% DR) was 77% in patients with BA and 25% in patients with AT (p = 0.017).(ABSTRACT TRUNCATED AT 250 WORDS)

Aortoiliac angioplasty: is there a need for other types of percutaneous intervention?

In a retrospective study, the authors compared results in 81 patients who underwent 117 percutaneous transluminal angioplasty (PTA) procedures in the iliac arteries and 21 patients who underwent iliac artery atherectomy. Both groups were similar with respect to symptoms and risk factors. The overall technical success rates were 97.4% for PTA and 100% for atherectomy. The initial clinical success was 92.8% for PTA and 100% for atherectomy. Complications requiring surgery occurred in four of 117 (3.4%) PTA and one of 21 (4.8%) atherectomy procedures. The 2-year patency rate for PTA was similar to that achieved with atherectomy in a smaller patient population. These results indicate that atherectomy does not offer any definite advantage over conventional PTA for the routine management of iliac lesions and make it difficult to justify the additional expense and complexity of this technique.

Evidence implicating nonmuscle myosin in restenosis. Use of in situ hybridization to analyze human vascular lesions obtained by directional atherectomy

BACKGROUND

Identification of genes that are specifically activated in restenosis lesions after percutaneous transluminal angioplasty represents a necessary step toward molecular manipulation designed to inhibit cellular proliferation responsible for such lesions. Whereas quiescent smooth muscle cells (contractile phenotype) preferentially express smooth muscle myosin, proliferating smooth muscle cells (synthetic phenotype) have been shown to preferentially express nonmuscle myosin in vitro. Accordingly, we analyzed the expression of a recently cloned isoform of human nonmuscle myosin heavy chain (MHC-B) in fresh human restenotic lesions.

METHODS AND RESULTS

A total of 10 lesions, including four restenosis (three superficial femoral arterial lesions and one saphenous vein bypass lesion) and six primary (four superficial femoral arterial lesions and two coronary arterial lesions) obtained percutaneously by directional atherectomy, were processed for examination by in situ hybridization. In total, 150 tissue sections of restenotic lesions (66 sections), primary lesions (78 sections), and normal internal mammary artery (six sections) were hybridized with the nonmuscle MHC-B probe. Restenotic lesions showed intense hybridization to the nonmuscle MHC-B cRNA probe, as demonstrated by a clustering of more than 20 grains per cell nucleus in 80% of the cells examined within a high-power field (x250); in contrast, an equivalent degree of hybridization was observed in only 7% of cells within primary lesions (p less than 0.001). Results of immunocytochemistry using monoclonal antibody to smooth muscle actin indicated that cells demonstrating strong hybridization were smooth muscle in origin.

CONCLUSIONS

These findings demonstrate that 1) human vascular tissue obtained by percutaneous directional atherectomy constitutes appropriate biopsy material for gene expression studies at the mRNA level, and 2) nonmuscle MHC-B mRNA is present in greater abundance among restenotic versus primary vascular stenoses. These observations thus provide a rational basis to explore restenotic lesions on a larger scale to identify genes that are activated in these lesions and establish potential targets for future gene therapy.

Migratory activity of human smooth muscle cells cultivated from coronary and peripheral primary and restenotic lesions removed by percutaneous atherectomy

BACKGROUND

The successful cultivation of human smooth muscle cells (SMC) from coronary and peripheral atherosclerotic lesions removed by percutaneous directional atherectomy is described.

METHODS AND RESULTS

Sixty-seven patients in whom plaque material was obtained compose the study population. A total of 73 lesions from both coronary (n = 38) and peripheral (n = 35) arteries of primary (n = 50) and restenotic origin (n = 23) were studied. Successful cultivation was significantly (p less than 0.001) dependent on the quantity of plaque material submitted. Fifty-five percent of patients in whom atherectomy specimens were removed from coronary lesions yielded an adequate SMC population in comparison to 89% of those from peripheral arteries (p less than 0.01). Cultivation was not dependent on the age and sex of patients, lesion origin, risk factors, medications, or incidence of unstable angina. In an attempt to quantify SMC activity, migratory velocity was measured with a computer-assisted motion analysis system. SMC migratory velocity was found to be significantly (p less than 0.001) greater in restenotic than in primary plaque material. This finding was confirmed for both coronary and peripheral lesions.

CONCLUSIONS

Our data suggest that elevated SMC migratory activity may be an important mechanism in the development of restenotic lesions.

Arterial response to mechanical injury: balloon catheter de-endothelialization

Coronary angioplasty has been used clinically for over a decade. Its initial promise as an alternative to coronary bypass surgery has only partially been fulfilled because of the high rate of post-operative restenosis. A number of animal models have been devised to study this phenomenon and although none is entirely satisfactory, they have, together with recent advances in molecular biology provided an insight into the cellular mechanisms that may contribute to this complication. This knowledge may ultimately lead to a means of therapeutic intervention. This review summarises our present understanding of the pathology of post-angioplasty re-stenosis as revealed by studies using the balloon catheter de-endothelialization model, and discusses some of the intervention strategies that have been attempted.

Effects of rotational atherectomy in normal canine coronary and diseased human cadaveric arteries: potential for plaque removal from distal, tortuous, and diffusely diseased vessels

To test the hypothesis that tortuous, diseased vessels could be successfully treated with a flexible rotational atherectomy device we evaluated the BARD atherectomy device with quantitative angiography and histology in normal canine coronary arteries and diseased human below-knee amputation specimens. The mid left anterior descending and the circumflex vessels were treated in 4 dogs serially with 1 wk separating treatments. The acute and follow-up anterior descending artery size was unchanged (1.41 mm before, 1.39 mm after, and 1.59 mm at 1 week). Similar findings were obtained in the circumflex vessels. In 4 adult human amputated legs, diseased peroneal or tibial arteries were treated with a significant reduction in the percent luminal diameter stenosis from 62.75 prior to intervention to 36.5 following intervention (p = 0.021). The luminal diameter increased from 0.81 to 1.54 mm (p = 0.06). In 2 canine arteries there was histologic evidence of localized perforation of the arterial wall, but there was no angiographic evidence of perforation or dissection and no significant myocardial necrosis in the distribution of the treated vessels at 1 wk. The majority of the diseased human vessels demonstrated smoothly cut atheromas with sparing of the media. The rotational atherectomy catheter system holds promise for removal of plaque in relatively small, diffusely diseased, tortuous vessels.

Intravascular ultrasound imaging for guidance of atherectomy and other plaque removal techniques

Intravascular ultrasound imaging provides a direct view of atherosclerotic disease, generating in vivo information about the depth and mechanical characteristics of plaque at any point in the vessel wall. For this reason, ultrasound has significant potential to serve as a guidance modality for catheter-based techniques designed to remove or ablate plaque. Although the current generation mechanical atherectomy, laser ablation and ultrasound pulverization techniques all have some specificity for attacking plaque as opposed to normal vessel wall, it appears that in practice all of these devices will continue to carry a risk of traumatizing or even perforating arteries. In addition, it seems highly likely that aggressive 'debulking' of plaque will require some type of guidance beyond angiography - a role which ultrasound is theoretically well suited to play. The purpose of this review is to consider the theoretical and practical applications of ultrasound imaging as a guide to catheter-based plaque removal and ablation techniques. Specific uses will be discussed with respect to both directional and coaxial therapeutic devices.

Directional coronary atherectomy for failed angioplasty due to occlusive coronary dissection

We describe a case in which coronary balloon angioplasty failed to improve sequential lesions and resulted in a long area of dissection between the stenoses. Directional coronary atherectomy of the occlusive dissection produced excellent angiographic improvement to achieve a successful result and avoid the need for urgent coronary bypass surgery. Directional coronary atherectomy represents a potentially useful treatment for PTCA-induced coronary dissection.

Ability of high-intensity ultrasound to ablate human atherosclerotic plaques and minimize debris size

To investigate whether high-intensity ultrasound can destroy atherosclerotic plaques while sparing the normal arterial wall, 279 normal human aortic sites and 119 fibrous and 193 calcified plaques, obtained from 24 necropsies, were insonified in a water tank, at 20 kHz and at 5 different power intensities, ranging from 68 W/cm2 (P1) to 150 W/cm2 (P5). These intensities were associated with a total excursion of the ultrasound irradiation apparatus tip from 90 to 268 microns, respectively. Time to perforate normal aortic sites and fibrous and calcified plaques was recorded at each intensity. There was no difference in perforation time between normal aortic sites and fibrous and calcified plaques when high-power levels (P2 to P5) were used. However, at the lowest power (P1), perforation time for the normal aortic wall was significantly longer than for fibrous and calcified plaques: 30 +/- 18 seconds (166 observations), 14 +/- 7 seconds (p less than 0.001) (78 observations) and 12 +/- 8 seconds (p less than 0.001) (115 observations), respectively. When perforation times for normal vessel wall versus fibrous plaque and normal vessel wall versus calcified plaque from the same necropsy specimen were compared in a pairwise manner, the results were: 29 +/- 13 vs 16 +/- 7 (p less than 0.001) (48 paired observations) and 26 +/- 9 vs 10 +/- 5 seconds (p less than 0.001) (55 paired observations), respectively. Regardless of whether paired or unpaired comparison was applied, no significant difference was found in perforation time between fibrous and calcified plaques. The debris did not differ in size as measured separately for normal sites and fibrous and calcified plaques by a computer-interfaced Channelizer and Coulter Counter system.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of angioscopy in the treatment of peripheral vascular disease with percutaneous atherectomy

The role of adjunctive video angioscopy was evaluated in 43 patients with symptomatic peripheral vascular disease undergoing percutaneous atherectomy with the Simpson atherocath. There were 57 target lesions (superficial femoral, n = 46; popliteal, n = 11) of which 33 were stenotic (86 +/- 11%) and 24 were total occlusions of 0.5 to 10.6 cm in length, determined by angiography. Intraluminal inspection, with angioscopes of 0.85 to 1.5 mm in outer diameter housed within a guide catheter, could be performed in 55 of 57 lesions (96%) before atherectomy and in 39 of these 55 (71%) after atherectomy. Failure to obtain an adequate image was usually due to insufficient irrigation, especially in recanalized vessels. In 13 of 23 successfully recanalized arteries (54%) the occlusion could be crossed by the angioscope itself, whereas in 10 cases (42%) a guidewire or a sheath introducer was necessary. Angioscopic passage revealed that often long total occlusions, determined by angiography, consisted of greater than or equal to 1 discrete occlusion with interposed patent thrombus-free vascular segments. After atherectomy, in 15 instances with an acceptable angiographic result, angioscopy was helpful in identifying residual plaques and flaps which then selectively underwent atherectomy. In conclusion, angioscopy proved to be a useful adjunct to angiography in optimizing vascular recanalization with percutaneous atherectomy.

Percutaneous transluminal angioplasty of the lower extremities by the vascular surgeon

As vascular surgeons, we performed 376 percutaneous transluminal angioplasties as follows: aorta and iliac arteries (148), infrainguinal arteries (191), and bypass grafts (21). Sixteen procedures were attempted but not completed. Neodymium-yttrium-aluminum-garnet laser thermoprobe was successfully used prior to balloon dilatations in 49 procedures. In contrast to our experience with operative intervention, percutaneous transluminal angioplasty was performed more frequently for claudication (75%), nondiabetics (72%), and women (45%). Median age was 71 years. Percutaneous transluminal angioplasty either preceded or followed proximal or distal open reconstruction in 58 extremities. Primary patency rates for iliac percutaneous transluminal angioplasties were: 94% at one month, 93% at six months, and 88% at one year. For infrainguinal percutaneous transluminal angioplasties they were 95%, 82%, and 70% at 1, 6, and 12 months, respectively. Repeat percutaneous transluminal angioplasty increased the one-year patency rates to 92% and 86% for iliac and infrainguinal percutaneous transluminal angioplasties, respectively. Preliminary data indicate that the six-month secondary patency rates were 82% for laser-assisted percutaneous transluminal angioplasty and 65% for percutaneous transluminal angioplasty of distal bypass grafts. The implementation of balloon angioplasty was facilitated by our 21 years of experience with arteriography. Percutaneous transluminal angioplasty has become a valuable adjunct to the practice of vascular surgery by expanding the therapeutic options for managing peripheral vascular occlusive disease.

Does the Kensey catheter keep a coaxial position inside the arterial lumen? An in-vitro angioscopic study

Angioscopy was used to evaluate the "self-centering" ability of three Kensey catheters (KC) with different flexibility: one 8Fr "peripheral" and two 5Fr "coronary" (I & II). Angioscopic observations were made inside arteries, 5-18 mm in diameter. There was a good correlation between flexibility and self-centering of the KC [r = 0.83, p less than 0.05]. Increasing the flow rate of rinsing solution from 18 to 60 ml/min prolonged coaxial position from 8.9 +/- 3.3 to 36 +/- 2.2 sec/min of activation [p less than 0.001]. A smaller effect on coaxial position was exerted by increasing cam speed from 5.2 +/- 0.7 to 19.2 +/- 1.6 sec/min (p less than 0.001). In conclusion, angioscopy showed that the KC has a limited ability to maintain a coaxial position inside the arterial lumen and operators cannot rely on its self-centering property.