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Biomedical subjects

M B Leon

Publications and source records attributed to M B Leon.

At least 271 records · Page 15Linked to original sources
PubMed1993

Clinical and angiographic outcome after directional coronary atherectomy. A qualitative and quantitative analysis using coronary arteriography and intravascular ultrasound.

To assess clinical and angiographic outcome after directional coronary atherectomy, the clinical course of 306 patients undergoing this procedure was reviewed. Directional atherectomy was successful in 290 (94.8%) procedures; complications developed in 8 (2.6%) patients. After atherectomy, percent diameter stenosis was reduced from 71 +/- 14 to 14 +/- 14% (p < 0.001) and minimal lumen diameter was increased from 0.87 +/- 0.42 to 2.55 +/- 0.57 mm (p < 0.001). In 128 (42%) patients, adjunct balloon angioplasty was performed to treat either complications or a residual stenosis > 30%. Intravascular ultrasound was also performed in 57 patients after directional atherectomy and demonstrated that a significant amount of residual plaque mass remained in lesions with a calcium arc > or = 90 degrees (17 +/- 5 mm2 vs 12 +/- 5 mm2 in lesions without calcium; p = 0.007). During the 11 +/- 6 month follow-up period, 69 (28.3%) patients developed recurrent clinical events (death, 5; Q wave myocardial infarction, 8; coronary bypass surgery, 31; coronary angioplasty, 36). Using a proportional hazards model, independent predictors of late clinical events included diabetes mellitus (relative risk [RR] = 1.95; p < 0.05), unstable angina (RR = 2.78; p < 0.005) and a prior history of restenosis (RR = 2.21; p < 0.01). We conclude that directional atherectomy is associated with high procedural success rates and infrequent complications in selected lesions subsets, although the degree of plaque resection may be limited if extensive calcium is present. Late clinical events develop in some (28%) patients after directional atherectomy, related to certain preprocedural clinical risk factors.

Atherectomy, Coronary↗
PubMed1993

A comparison of directional atherectomy with coronary angioplasty in patients with coronary artery disease. The CAVEAT Study Group.

BACKGROUND: Directional coronary atherectomy is a new technique of coronary revascularization by which atherosclerotic plaque is excised and retrieved from target lesions. With respect to the rate of restenosis and clinical outcomes, it is not known how this procedure compares with balloon angioplasty, which relies on dilation of the plaque and vessel wall. We compared the rate of restenosis after angioplasty with that after atherectomy. METHODS: At 35 sites in the United States and Europe, 1012 patients were randomly assigned to either atherectomy (512 patients) or angioplasty (500 patients). The patients underwent coronary angiography at base line and again after six months; the paired angiograms were quantitatively assessed at one laboratory by investigators unaware of the treatment assignments. RESULTS: Stenosis was reduced to 50 percent or less more often with atherectomy than with angioplasty (89 percent vs. 80 percent; P < 0.001), and there was a greater immediate increase in vessel caliber (1.05 vs. 0.86 mm, P < 0.001). This was accompanied by a higher rate of early complications (11 percent vs. 5 percent, P < 0.001) and higher in-hospital costs ($11,904 vs $10,637; P = 0.006). At six months, the rate of restenosis was 50 percent for atherectomy and 57 percent for angioplasty (P = 0.06). However, the probability of death or myocardial infarction within six months was higher in the atherectomy group (8.6 percent vs. 4.6 percent, P = 0.007). CONCLUSIONS: Removing coronary artery plaque with atherectomy led to a larger luminal diameter and a small reduction in angiographic restenosis, the latter being confined largely to the proximal left anterior descending coronary artery. However, atherectomy led to a higher rate of early complications, increased cost, and no apparent clinical benefit after six months of follow-up.

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PubMed1993

Rotational coronary atherectomy after unsuccessful coronary balloon angioplasty.

The clinical and angiographic outcome of patients undergoing rotational coronary atherectomy after unsuccessful balloon angioplasty was evaluated using quantitative angiographic methods to provide insight into this procedure's mechanism of benefit. During the study period, 41 patients (50 lesions) were referred for rotational atherectomy after standard balloon angioplasty was unsuccessful. After rotational atherectomy, percent diameter stenosis was reduced from 72 +/- 14% to 41 +/- 16% (p < 0.001); adjunct balloon angioplasty was performed in 44 lesions (88%), resulting in a 25 +/- 17% final diameter stenosis (p < 0.001). The acute gain in minimal lumen diameter was 1.20 +/- 0.59 mm. In lesions needing adjunct balloon dilatation, lesion stretch was 73 +/- 27%, and elastic recoil was 22 +/- 18%, with no variation by etiology of the initial balloon failure. Overall angiographic success (< 50% residual diameter stenosis) was obtained in 49 lesions (98%). Procedural success, defined as < 50% residual diameter stenosis and the absence of major in-hospital complications (death, Q-wave myocardial infarction or emergency bypass surgery), was obtained in 37 of 41 procedures (90%); complications developed in 3 patients (7%), including 2 who needed emergency bypass surgery after development of delayed abrupt closure. It is concluded that rotational coronary atherectomy may be used in selected patients when standard balloon angioplasty is unsuccessful. Its mechanism of benefit appears related, at least in part, to changes in plaque compliance resulting from partial atheroma ablation.

Angioplasty, Balloon, Coronary↗
PubMed1993

Preliminary experience with adjunct directional coronary atherectomy after high-speed rotational atherectomy in the treatment of calcific coronary artery disease.

A high-speed rotational atherectomy was performed followed by adjunct directional atherectomy in 10 patients with symptomatic coronary artery disease and calcified target lesions and the results were evaluated using quantitative coronary arteriography and intravascular ultrasound. Target lesion calcium is common in obstructive coronary artery disease. High-speed rotational coronary atherectomy preferentially abrades noncompliant atherosclerotic plaque material, especially calcium, but often requires adjunct balloon angioplasty to achieve optimal lumen dimensions. Directional coronary atherectomy has limited efficacy in heavily calcified plaque; usually, it is a definitive primary procedure in large arteries with noncalcified target lesions. Neither of these devices alone is effective in treating calcified target lesions in large coronary arteries. Before intervention, after rotational and adjunct directional atherectomy, these measurements were obtained: quantitative coronary arteriographic measurements of minimal lumen diameter and percent diameter stenosis and intravascular ultrasound measurements of external elastic membrane, lumen, and plaque+media cross-sectional areas; percent cross-sectional narrowing; minimal lumen diameter; and target-lesion arc of calcium. With use of quantitative coronary arteriography, the preintervention minimal lumen diameter measured 0.7 +/- 0.4 mm, increased to 1.5 +/- 0.5 mm after rotational atherectomy (p = 0.0013) and to 2.5 +/- 0.3 mm after adjunct directional atherectomy (p < 0.001). The preintervention percent diameter stenosis measured 78 +/- 15%, decreased to 50 +/- 17% after rotational atherectomy (p = 0.0011), and to 17 +/- 11% (p < 0.001) after adjunct directional coronary atherectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Atherectomy, Coronary↗
PubMed1993

Quantitative analysis of factors influencing late lumen loss and restenosis after directional coronary atherectomy.

Although encouraging initial results have been demonstrated after directional atherectomy, the mechanisms and predictors of late lumen loss and restenosis after this procedure have not been evaluated. To examine these issues, clinical and angiographic follow-up were obtained in 262 (96%) and 212 (77%) of 274 patients undergoing successful directional coronary atherectomy. Symptom recurrence developed in 87 (33%) patients and angiographic restenosis was found in 93 (44%). Restenosis was highest in re-stenotic lesions in saphenous vein grafts (78% [95% confidence interval (CI): 56 to 100%]) and lowest in new-onset lesions in the left anterior descending (27% [95% CI: 15 to 39%]) and circumflex (14% [95% CI: 0 to 43%]) coronary arteries. Residual lumen diameter immediately after atherectomy was smaller in re-stenotic lesions (p = 0.002) and in lesions > or = 10 mm in length (p = 0.02). Late lumen loss was associated with the minimal lumen diameter immediately after atherectomy (p < 0.001), saphenous vein graft lesion location (p = 0.008), and male gender (p = 0.02). Re-stenotic lesions (p < 0.001), lesions > or = 10 mm in length (p = 0.018), saphenous vein graft lesion location (p = 0.025) and male gender (p = 0.045) were independent predictors for restenosis. It is concluded that restenosis after directional atherectomy is related both to factors resulting in a suboptimal initial result and to factors contributing to excessive late lumen loss. These results may have implications for lesion selection in patients undergoing directional coronary atherectomy.

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PubMed1993

Sequential intravascular ultrasound characterization of the mechanisms of rotational atherectomy and adjunct balloon angioplasty.

OBJECTIVES: The purpose of this study was to use sequential intravascular ultrasound imaging before intervention, after rotational atherectomy and after adjunct balloon angioplasty to characterize the mechanisms of lumen enlargement after each. BACKGROUND: Rotational atherectomy uses a high speed, rotating, diamond-tipped elliptic burr to abrade atherosclerotic plaque to increase lumen size. In vitro studies have shown that high speed rotational atherectomy selectively abrades hard, especially calcified, plaque elements. However, rotational atherectomy procedures usually require adjunct balloon angioplasty. METHODS: Forty-eight lesions in 46 patients were treated with rotational atherectomy followed by adjunct balloon angioplasty in 44. Quantitative coronary arteriographic and intravascular ultrasound measurements of the target lesion were made before intervention, after rotational atherectomy and after balloon angioplasty. RESULTS: Before intervention, target lesion external elastic membrane area measured 17.3 +/- 5.9 mm2, lumen area measured 1.8 +/- 0.9 mm2 and plaque plus media area measured 15.7 +/- 4.1 mm2. After rotational atherectomy, lumen area increased, plaque plus media area decreased, arc of target lesion calcium decreased and 26% of the target lesions had dissection planes. After adjunct balloon angioplasty, external elastic membrane area increased, lumen area increased, plaque plus media area did not change and 77% of the target lesions had dissection planes. Arterial expansion was seen in 80% of lesions. The pattern of dissection plane location, which was predominantly within calcified plaque after rotational atherectomy, became predominantly adjacent to calcified plaque after adjunct balloon angioplasty (p = 0.008). CONCLUSIONS: Sequential intravascular ultrasound imaging shows that high speed rotational atherectomy causes lumen enlargement by selective ablation of hard, especially calcific, atherosclerotic plaque with little tissue disruption and rare arterial expansion. Adjunct balloon angioplasty further increased lumen area by a combination of arterial dissection and arterial expansion, especially of compliant, noncalcified plaque elements.

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PubMed1993

Chronic total obstruction and short-term outcome: the Excimer Laser Coronary Angioplasty Registry experience.

Percutaneous transluminal coronary angioplasty for chronic total obstructions is associated with significantly decreased success rates in comparison with those for dilation of subtotal stenoses. Failure usually results from inability to cross the occlusive lesion with a guidewire, although it may result from inability to pass the balloon catheter after the guidewire has been passed. In the Excimer Laser Coronary Angioplasty Registry, 172 chronic total obstructions were treated in 162 patients (10.3% of the 1,569 patients entered). For chronic total obstructions, passage of a guidewire is a prerequisite for laser angioplasty. Once a guidewire crossed an occlusion, the overall laser success rate for treatment of chronic total obstructions was 83%; the extent of stenosis decreased from 100% to 55 +/- 26%. Success was independent of length of the occlusive lesion. In 74% of patients, adjunctive percutaneous transluminal coronary angioplasty was used after laser angioplasty. A final procedural success, defined as residual stenosis of less than 50% and no major complication (coronary artery bypass grafting, myocardial infarction, or death), was achieved in 90%. Major complications were infrequent; 1.2% of patients required coronary artery bypass grafting, and 1.9% had a Q-wave myocardial infarction. Only one death occurred. The use of laser angioplasty may be of particular value when chronic total obstructions can be crossed with a guidewire but not with a conventional balloon catheter or when the occlusion is confirmed to be extremely long.

Adult↗
PubMed1993

Treatment of refractory coronary occlusions with a new excimer laser catheter: preliminary clinical observations.

BACKGROUND: Total coronary occlusion is a frequent cause of procedural failure after coronary angioplasty, often because of the inability to recanalize the occluded segment with a conventional coronary guidewire. The novel excimer laser catheter described in this report contains a highly efficient, pulsed excimer laser guidewire designed to create a small channel within the occluded coronary segment. A preliminary report of the safety and efficacy of this excimer laser catheter is provided. METHODS: Ten patients with refractory coronary occlusions that could not be crossed by experienced operators using conventional guidewire techniques were treated using a novel laser catheter system. The laser catheter consisted of a densely packed, multiple fiber, helical guidewire measuring 0.020 inches (0.51 mm) in diameter, interfacing a 308 nm excimer laser system and delivering 70-80 mJ/mm2 of energy to the output surface. After the laser guidewire had been advanced to the occlusion site, laser energy was applied to ablate a channel as the wire was advanced through the occlusion. Once the occlusion had been recanalized, standard concentric laser or balloon angioplasty was performed. RESULTS: Complete recanalization was achieved in three total occlusions, and partial recanalization was established in a further three; thus, normal coronary perfusion was attained in six out of 10 patients after adjunct excimer laser or balloon angioplasty. The final minimum lumen diameter averaged 1.51 mm and the final residual stenosis diameter was 27%. In two patients the procedure was unsuccessful but without significant complications; two other patients developed limited coronary perforations without clinical sequelae. CONCLUSION: Refractory coronary occlusions were successfully recanalized in six out of 10 patients using a novel excimer laser catheter. Treatment failures in four patients were not associated with major complications, although limited coronary perforation occurred in two patients.

Angioplasty, Balloon, Coronary↗
PubMed1993

Feasibility and drug delivery efficiency of a new balloon angioplasty catheter capable of performing simultaneous local drug delivery.

BACKGROUND: Local drug delivery at angioplasty treatment sites may improve acute and long-term results after angioplasty. A new dual-purpose balloon angioplasty catheter containing intramural channels and exterior pores ('channeled balloon') was designed to allow local drug delivery at low pressure without jet streams during simultaneous balloon angioplasty. METHODS: Acute feasibility studies were performed in normal ex-vivo and in-vivo arteries (three canine arteries and three rabbits with normal iliac arteries), in which 2 ml of marker agents were locally infused at 2 atm during simultaneous angioplasty at 6 atm with the channeled balloon. Histology, radioactive counting, and autoradiography were performed to determine the intramural localization of the delivered markers. The in-vitro efficiency of acute local drug delivery was estimated in seven normal canine arteries by infusing 3H-heparin and radioactive counting. RESULTS: Histology revealed the presence of markers in the inner third of the media in all ex-vivo samples, and markers in all in-vivo iliac arteries except for one, whereas control segments had no intramural staining. Autoradiography documented transmural radioactive granules. Radioactive counts were 40- to 263-fold higher in those locally treated with the radioactive marker agent. Efficiency of the acute local delivery was estimated by dividing the actual counts by the expected counts; it ranged from 24 to 48%. CONCLUSION: This study demonstrates that the channeled balloon is capable of delivering drugs locally at low pressure in adequate concentrations during simultaneous high-pressure balloon angioplasty in normal arteries.

Angioplasty, Balloon, Coronary↗
PubMed1993

Vascular complications after balloon and new device angioplasty.

BACKGROUND: Despite their potential advantages, new coronary angioplasty devices may be associated with more frequent vascular complications than noted after standard balloon angioplasty, theoretically due to the larger sheaths and prolonged periods of anticoagulation required by some of these devices. This study sought to identify the incidence, predictors, and clinical outcome of vascular complications after new device angioplasty. METHODS AND RESULTS: The clinical course of 1413 patients was reviewed after balloon or new device angioplasty. Vascular complications were defined as formation of a pseudoaneurysm, arteriovenous fistula, retroperitoneal hematoma, or groin hematoma associated with a > 15-point hematocrit drop or the need for surgical repair. Stepwise logistic regression was used to identify independent predictors for vascular complications. Vascular complications developed after 84 (5.9%) procedures; they occurred more frequently after intracoronary stenting (14.0%) and extraction atherectomy (12.5%) than after balloon angioplasty (3.2%) (odds ratios, 4.86; P < .001, and 4.26, P < .05, respectively). Independent predictors of vascular complications included the use of intraprocedural thrombolytic agents (P < .01), intracoronary stenting (P < .005), or extraction atherectomy (P < .05); high maximum creatinine level (P < .005); low nadir platelet count (P < .001); longer periods of excess anticoagulation (P < .05); and the need for repeat coronary angioplasty (P < .005). Vascular complications were not related to the size of the arterial sheath used. CONCLUSIONS: Vascular complications developed more frequently after new device angioplasty than after balloon angioplasty, with the risk for vascular complications directly related to the degree of periprocedural anticoagulation.

Aneurysm, False↗
PubMed1993

Smooth muscle cell abundance and fibroblast growth factors in coronary lesions of patients with nonfatal unstable angina. A clue to the mechanism of transformation from the stable to the unstable clinical state.

BACKGROUND: The mechanisms responsible for the transformation of stable angina to unstable angina, a major cause of morbidity and mortality, are commonly believed to be plaque rupture and thrombosis. We determined whether additional mechanisms are operative by analyzing the histopathology and immuno-histopathology of coronary plaques retrieved by directional atherectomy of patients with unstable angina in whom no intraluminal thrombus was demonstrated by angiography. METHODS AND RESULTS: The histological findings of atherectomy specimens from 34 patients with unstable angina were compared with those of 24 patients with postangioplasty restenosis, whose lesions are known to be composed of smooth muscle cells (SMCs), and 10 patients with stable angina, whose lesions contain relatively few SMCs. We also studied the expression of acidic and basic fibroblast growth factors (aFGF and bFGF), whose role in the vascular response to injury has been established. Specimens from unstable angina resembled those from postangioplasty restenosis in regard to SMC abundance (scale, 0 to 3; 1.4 +/- 0.9 versus 1.7 +/- 0.9; P = NS), and both differed from those of stable angina. Thrombus and/or hemorrhage occurred in only 34% of patients with unstable angina (compared with 8% of restenosis patients and in none of stable angina patients). Active lesions (defined as lesions (defined as lesions containing one or more of the following: thrombus, hemorrhage, abundant and disorganized SMCs in the presence of loose connective tissue, or inflammatory infiltrate) were observed in 56% of the unstable angina patients and in 50% of the restenosis patients but in none of the stable angina patients. The expression of aFGF and bFGF was detected in 80% to 100% of unstable angina (n = 11) and restenosis (n = 10) specimens but in only 1 of 5 stable angina specimens. CONCLUSIONS: Microscopic evidence of thrombosis and plaque rupture occurred in only one third of unstable angina patients, selected because they had no angiographic evidence of intracoronary thrombus. Moreover, their lesions resembled those of restenosis patients in regard to SMC abundance, lesion activity, and the expression of aFGF and bFGF. Our findings therefore suggest that an alternative mechanism to plaque rupture and thrombus formation may be operative in the precipitation of unstable angina; namely, in a subset of patients, SMC proliferation may lead to gradual plaque expansion and thereby to lumenal narrowing and unstable angina. Our data also suggest a role for aFGF and bFGF in this process.

Adult↗
PubMed1993

Transcatheter device synergy: preliminary experience with adjunct directional coronary atherectomy following high-speed rotational atherectomy or excimer laser angioplasty in the treatment of coronary artery disease.

We performed high-speed rotational atherectomy followed by adjunct directional atherectomy in 10 patients and excimer laser angioplasty followed by directional atherectomy in 6 patients and evaluated the results using quantitative coronary arteriography and intravascular ultrasound. Quantitative coronary arteriographic measurements of minimal lumen diameter and % diameter stenosis and intravascular ultrasound measurements of external elastic membrane, lumen, and plaque + media cross-sectional areas; % cross-sectional narrowing; minimal lumen diameter; and target-lesion arc of calcium were made pre-intervention, after rotational atherectomy or excimer laser angioplasty, and after adjunct directional atherectomy. Rotational atherectomy: Using quantitative coronary arteriography, the pre-intervention minimum lumen diameter measured 0.7 +/- 0.4 mm, increased to 1.5 +/- 0.5 mm after rotational atherectomy, and to 2.5 +/- 0.3 mm after adjunct directional atherectomy. The pre-intervention % diameter stenosis measured 78 +/- 15%, decreased to 50 +/- 17% after rotational atherectomy, and to 17 +/- 11% after adjunct directional coronary atherectomy. Intravascular ultrasound showed arcs of target lesion calcification that measured 271 +/- 92 degrees pre-intervention, decreased to 210 +/- 120 degrees after rotational atherectomy, and to 163 +/- 122 degrees after adjunct directional atherectomy, with distinct directional atherectomy cuts into calcium. Pre-intervention, target lesion external elastic membrane area measured 20.4 +/- 2.3 mm2, lumen area measured 1.5 +/- 0.6 mm2, plaque + media are measured 18.9 +/- 2.3 mm2, and % cross-sectional narrowing measured 93 +/- 3.(ABSTRACT TRUNCATED AT 250 WORDS)

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