Gregory C. Robertson

Transluminal atherectomy for occlusive peripheral vascular disease.

Sixty-one patients with occlusive peripheral vascular disease were treated with transluminal atherectomy, a catheter-mediated technique for removal of atheroma. The technique was performed using 7Fr, 9Fr or 11Fr atherectomy catheters. Mean percent diameter stenosis was reduced from 71 to 23%, by removal of 831 atheromatous specimens in 949 passes of the cutting element through 136 stenoses in 61 patients. All specimens removed were sent for histopathologic examination to determine the components of the atheroma removed, which differed for specimens removed from original vs restenotic lesions. Percent stenosis was reduced to less than 45% in 118 of 136 stenoses (87%). Complications included 1 thrombus, which resolved after intraarterial infusion of streptokinase and 1 probable distal embolization without sequelae. Three angiographic dissections occurred without impairment of blood flow. There were no instances of acute occlusion, vascular spasm or vessel perforation. Six-month follow-up angiography was performed showing that patients who had a residual stenosis less than 30% after initial atherectomy had a lower restenosis rate (18%) than patients with initial residual stenoses greater than 30% (52%); this result demonstrated the importance of performing more complete atherectomy. Transluminal atherectomy appears to be an effective, predictable and safe method for removing occlusive atheromatous deposits from peripheral arteries.

Directional atherectomy for treatment of restenosis within coronary stents: clinical, angiographic and histologic results

OBJECTIVES The safety and long-term results of directional coronary atherectomy in stented coronary arteries were determined. In addition, tissue studies were performed to characterize the development of restenosis. METHODS Directional coronary atherectomy was performed in restenosed stents in nine patients (10 procedures) 82 to 1,179 days after stenting. The tissue was assessed for histologic features of restenosis, smooth muscle cell phenotype, markers of cell proliferation and cell density. A control (no stenting) group consisted of 13 patients treated with directional coronary atherectomy for restenosis 14 to 597 days after coronary angioplasty, directional coronary atherectomy or laser intervention. RESULTS Directional coronary atherectomy procedures within the stent were technically successful with results similar to those of the initial stenting procedure (2.31 +/- 0.38 vs. 2.44 +/- 0.35 mm). Of five patients with angiographic follow-up, three had restenosis requiring reintervention (surgery in two and repeat atherectomy followed by laser angioplasty in one). Intimal hyperplasia was identified in 80% of specimens after stenting and in 77% after coronary angioplasty or atherectomy. In three patients with stenting, 70% to 76% of the intimal cells showed morphologic features of a contractile phenotype by electron microscopy 47 to 185 days after coronary intervention. Evidence of ongoing proliferation (proliferating cell nuclear antigen antibody studies) was absent in all specimens studied. Although wide individual variability was present in the maximal cell density of the intimal hyperplasia, there was a trend toward a reduction in cell density over time. CONCLUSIONS Although atherectomy is feasible for the treatment of restenosis in stented coronary arteries and initial results are excellent, recurrence of restenosis is common. Intimal hyperplasia is a nonspecific response to injury regardless of the device used and accounts for about 80% of cases of restenosis. Smooth muscle cell proliferation and phenotypic modulation toward a contractile phenotype are early events and largely completed by the time of clinical presentation of restenosis. Restenotic lesions may be predominantly cellular, matrix or a combination at a particular time after a coronary procedure.

Effect of lesion characteristics on outcome of directional coronary atherectomy

Directional coronary atherectomy, a new transluminal procedure for treatment of obstructive lesions in coronary arteries by excision and removal of tissue, was performed on 447 lesions in 382 procedures. Successful outcome, defined as a reduction of stenosis by greater than or equal to 20% with a less than 50% residual stenosis, was achieved in 89.5% of lesions and mean stenosis was reduced from 75.9 +/- 13.3% to 14.5 +/- 22.1% (p less than 0.001). Complications included vessel occlusion during the procedure, 2.4%; vessel occlusion after the procedure, 1.3%; new lesion, 0.5%; nonobstructive guiding catheter-induced dissection, 0.3%; perforation, 0.8%; distal embolization, 2.1%; Q wave myocardial infarction, 0.8% and non-Q wave myocardial infarction, 4.2%. Twelve patients (3.1%) required coronary artery bypass surgery for these complications. The atherectomy success rate was greater than 80% and the combined atherectomy and angioplasty success rate was greater than 90% for complex morphologic features such as eccentric lesions, lengthy lesions, lesions with abnormal contour, angulated lesions, ostial lesions and lesions with branch involvement. In the presence of calcific deposition, atherectomy success rate was 52% for primary lesions and 83% for restenosed lesions. Among angiographically complex lesions, calcium was the predictor for failed atherectomy (p less than 0.0001). In summary, directional coronary atherectomy is safe and effective for treatment of obstructive lesions in coronary arteries in selected cases. In particular, it achieves a high success rate in lesions with complex morphologic characteristics, such as eccentricity, abnormal contour and ostial involvement.

Restenosis after directional coronary atherectomy

OBJECTIVES This study evaluates the incidence of restenosis after successful directional coronary atherectomy and identifies risk factors for restenosis. BACKGROUND Directional coronary atherectomy has been shown to be a safe and effective treatment of obstructive coronary artery disease; however, information regarding restenosis is limited. METHODS Between October 1986 and December 1989, 289 patients with 332 lesions were successfully treated with directional coronary atherectomy and followed up prospectively. Clinical follow-up information was available for 98% and angiographic follow-up information was obtained for 82% at approximately 6 months, or earlier if symptoms recurred. Angiograms were quantitatively analyzed. Restenosis was defined as greater than 50% stenosis at the site of intervention. RESULTS Seventy-four percent of patients were either asymptomatic or clinically improved after the procedure. Thirty-two percent were subsequently treated by coronary artery bypass surgery (14%), percutaneous transluminal coronary angioplasty (4%) or repeat atherectomy (13%). Angiographic evidence of restenosis was observed in 42%. The restenosis rate in native coronary arteries was 31% for primary lesions and 28% and 49%, respectively, for lesions treated with one or two previous angioplasty procedures. The restenosis rate for saphenous vein grafts was 53% for primary lesions and 58% and 82%, respectively, for lesions treated with one or two previous angioplasty procedures. The median interval to angiographically documented restenosis was 133 days. A higher restenosis rate was associated with a saphenous vein graft, hypertension, a longer lesion (greater than or equal to 10 mm), a smaller vessel diameter (less than 3 mm), a noncalcified lesion and use of a smaller (6F) device. CONCLUSIONS Restenosis remains a limitation of directional coronary atherectomy. A subset of patients with larger vessels, shorter lesions or lesions treated with a larger (7F) device may have a more favorable outcome.

Comparison of dissection rates and angiographic results following directional coronary atherectomy and coronary angioplasty

Directional coronary atherectomy is a new percutaneous transluminal technique for treating occlusive coronary artery disease. In this study, angiographic results (i.e., residual stenosis and angiographic evidence of postprocedure dissection) after directional coronary atherectomy and balloon angioplasty were compared. The atherectomy group consisted of 91 lesions in 83 consecutive patients who underwent either left anterior descending artery or right coronary artery atherectomy. The angioplasty group consisted of 91 lesions in 84 patients that were matched with the atherectomy lesions with respect to vessel and whether the lesion was a restenosis lesion. The mean preprocedure diameter stenosis was 76% in both groups as measured quantitatively with electronic calipers. After the procedure, the mean residual diameter stenosis of the atherectomy lesions was 13 +/- 17%, whereas for the angioplasty lesions it was 31 +/- 18% (p less than 0.001). Success rates in both groups were similar (94.5 and 93.4%, respectively). The incidence of postprocedure dissection was 11% in the atherectomy group and 37% in the angioplasty group (p less than 0.0001). Directional coronary atherectomy results in significantly improved postprocedure angiographic appearances due to significantly less severe residual stenosis and lower incidence of dissection.

Clinical applications of intravascular ultrasound imaging in atherectomy

This paper discusses the potential application of intravascular ultrasound imaging in the context of catheter-based atherectomy. The advantages and limitations of ultrasound in this application are discussed, and representative cases are presented.

Early Experience with a Novel Plaque Excision System for the Treatment of Complex Coronary Lesions

The use of directional coronary atherectomy (DCA) in current practice has been limited. The SilverHawk System is a newly developed plaque excision device that aims to overcome the drawbacks of prior DCA platforms. The device was evaluated in a porcine coronary model and in a series of patients. Procedural variables along with outcomes were reviewed. Quantitative angiography (QCA) was performed and excised tissue fragments were weighed and examined histologically. In porcine cases, pretreatment MLD increased from 0.51 ± 0.26 to 2.36 ± 0.59 mm postdebulking and 19.9 ± 7.6 mg of tissue was retrieved. In human cases, pretreatment MLD increased from 0.8 ± 0.4 to 2.2 ± 0.5 mm postdebulking and 15.2 ± 7.8 mg of tissue was retrieved without complications. These data show that the SilverHawk System may offer significant utility in treating a wide variety of complex coronary lesions. Catheter Cardiovasc Interv 2004;61:35–43.

Restenosis: Directional Coronary Atherectomy

The concept of atherectomy was developed by J. B. Simpson to overcome some of the limitations of PTCA with the hypothesis that removal of tissue from an obstructed vessel would create a smooth and wide lumen [1, 2]. A smooth, wide lumen without dissection may prevent acute occlusion or reduce thrombus formation, thus improving the acute outcome. Improved flow pattern may prevent platelet aggregation or thrombus formation which are potential triggers for smooth muscle cell proliferation. Furthermore, a wide lumen following intervention may allow some intimal hyperplastic tissue to grow during the healing process without creating a hemodynamically significant stenosis. There is, therefore, the potential that atherectomy may reduce restenosis.