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M McIvor

Publications and source records attributed to M McIvor.

9 recordsLinked to original sources
PubMed1998

Acute results, complications, and effect of lesion characteristics on outcome with the solid-state, pulsed-wave, mid-infrared laser angioplasty system: final multicenter registry report. Holmium:YAG Laser Multicenter Investigators.

BACKGROUND AND OBJECTIVE: The solid-state, mid-infrared holmium:YAG laser (2.1 microm wavelength) is a relatively new percutaneous device that has recently been evaluated in a multicenter study. Because of its unique wavelength and photoacoustic effects on atherosclerotic plaques, this laser may be useful in treatment of symptomatic patients with coronary artery disease. This study sought to evaluate the safety and efficacy of mid-infrared laser angioplasty in the treatment of coronary artery lesions. PATIENTS AND METHODS: Laser angioplasty was performed on 2,038 atherosclerotic lesions in 1,862 consecutive patients with a mean age of 61 +/- 11 years. Clinical indications included unstable angina (69%), stable angina (20%), acute infarction (6%), and positive exercise test (5%). Complex lesion morphology included eccentricity (62%), thrombus (30%), total occlusion (27%), long lesions (14%), and saphenous vein grafts (11%). RESULTS: This laser catheter alone successfully reduced stenosis (>20%) in 87% of lesions. With adjunct balloon angioplasty, 93% procedural success was achieved. The presence of thrombus within the target lesion was a predictor of procedural success (OR = 2.0 [95% confidence interval 2.0, 4.0], P = .04). Bifurcation lesions (OR = 0.5 [95% confidence interval 0.2, 1.0], P = .05) and severe tortuosity of the treated vessel (OR = 0.4 [95% confidence interval 0.2, 0.9], P = .02) were identified as significant predictors of decreased laser success. Calcium within the lesion was associated with reduced procedural success (OR = 0.57 [95% confidence interval 0.34, 0.97], P = .03), and calcified lesions required significantly more energy pulses than noncalcified lesions (119 +/- 91 pulses vs. 101 +/- 86 pulses, respectively, P = .0002). Complications included in-hospital bypass surgery 2.5%, Q-wave myocardial infarction 1.2%, and death 0.8%. Perforation occurred in 2.2% of patients; major dissection in 5.8% of patients, and spasm in 12% of patients. No predictor of major complications was identified. Six-month angiographic restenosis was documented in 54% of patients, and clinical restenosis occurred in 34% of patients. CONCLUSION: Mid-infrared laser has a safety profile similar to that of other debulking devices. This laser may be useful in select patients presenting with acute ischemic syndromes associated with intracoronary thrombus; however, like other coronary lasers, it is limited by the need for adjunctive balloon angioplasty and/or stenting to achieve adequate final luminal diameter. No beneficial effects on reducing 6-month restenosis rates were observed.

Aluminum Silicates↗
PubMed1998

Modifiable risk factors for vascular access site complications in the IMPACT II Trial of angioplasty with versus without eptifibatide. Integrilin to Minimize Platelet Aggregation and Coronary Thrombosis.

OBJECTIVES: This study was designed to identify potential predictors of vascular access site (VAS) complications in the large-scale Integrilin to Minimize Platelet Aggregation and Coronary Thrombosis (IMPACT) II trial, which studied angioplasty with versus without a new glycoprotein (GP) IIb/IIIa receptor inhibitor (eptifibatide). BACKGROUND: GP IIb/IIIa receptor inhibition during coronary interventions has been associated with excess VAS complications. If other predictors of VAS complications could be identified, they might be manipulated to reduce complications. METHODS: A total of 4,010 patients undergoing percutaneous transluminal coronary revascularization (PTCR) were randomized into one of three bolus/20- to 24-h infusion arms: placebo bolus/placebo infusion; 135-microg/kg body weight eptifibatide bolus/0.5-microg/kg per min eptifibatide infusion; or 135-microg/kg eptifibatide bolus/0.75-microg/kg per min eptifibatide infusion. Heparin during the procedure was weight adjusted and stopped 4 h before sheaths were removed. Logistic regression modeling was used to identify independent predictors of VAS complications. RESULTS: VAS complications were more common in patients treated with eptifibatide (9.9% vs. 5.9% placebo-treated patients, p < 0.001). Multivariate analysis identified eptifibatide therapy (p < 0.0001), advanced age (p = 0.0001), longer time to sheath removal (p = 0.0002), stent placement (with intense post-stent anticoagulation) (p = 0.0004), female gender (p = 0.0006), PTCR within 24 h of thrombolytic therapy (p = 0.002), larger heparin doses during PTCR (p = 0.009), major coronary dissection (p = 0.03) and placement of a venous sheath (p = 0.04) as independent predictors of VAS complications. CONCLUSIONS: VAS complications may be reduced by early sheath removal, by avoiding placement of venous sheaths and by limiting heparin dosing to avoid excessive activated clotting times. Early sheath removal during inhibition of platelet aggregation by eptifibatide is feasible.

Aged↗
PubMed1997

Prospective, randomized, multicenter comparison of laser-facilitated balloon angioplasty versus stand-alone balloon angioplasty in patients with obstructive coronary artery disease. The Laser Angioplasty Versus Angioplasty (LAVA) Trial Investigators.

OBJECTIVES: The goal of this study was to examine the relative safety and efficacy of laser-facilitated percutaneous transluminal coronary angioplasty (PTCA) versus "stand-alone" PTCA. BACKGROUND: Plaque debulking with lasing before PTCA may result in improved lumen dimensions and decreased rates of periprocedural ischemic complications, thus improving short- and long-term outcomes after percutaneous intervention. The mid-infrared holmium:yttrium-aluminum-garnet (YAG) laser has been shown to be effective in a variety of plaque subtypes and may be particularly useful in high risk acute ischemic syndromes. METHODS: A total of 215 patients (mean [+/-SD] age 61 +/- 12 years) with 244 lesions were prospectively randomized at 14 clinical centers to laser versus stand-alone PTCA. After laser treatment, all patients underwent PTCA; 148 patients (69%) had unstable angina. RESULTS: The procedural success rate without major catheterization laboratory complications was similar in patients assigned to laser treatment or PTCA alone (96.6% vs. 96.9%, p = 0.88), as was the in-hospital clinical success rate (89.7% vs. 93.9%, p = 0.27). There was no difference in postprocedural diameter stenosis after laser treatment compared with PTCA (18.3% +/- 13.6% vs. 19.5% +/- 15.1%, p = 0.50). However, use of the laser, versus PTCA alone, did result in significantly more major and minor procedural complications (18.0% vs. 3.1%, p = 0.0004), myocardial infarctions (4.3% vs. 0%, p = 0.04) and total in-hospital major adverse events (103% vs. 4.1%, p = 0.08). At a mean follow-up time of 11.2 +/- 7.7 months, there were no differences in late or event-free survival in patients assigned to laser treatment versus PTCA alone. CONCLUSIONS: Compared with stand-alone PTCA, laser-facilitated PTCA results in a more complicated hospital course, without immediate or long-term benefits.

Angioplasty, Balloon, Coronary↗
PubMed1995

Solid-state, pulsed-wave, mid-infrared coronary laser angioplasty in de novo versus restenosis lesions: observations from a multicenter study.

The following is a study of the response of de novo versus restenosis coronary lesions to pulsed-wave, mid-infrared (holmium:YAG) laser assisted angioplasty. De novo lesions contain thrombi, cholesterol, and fibrosis, whereas restenotic lesions are composed of smooth muscle cells corresponding to injury caused by preceding balloon inflations. It is not known whether the different composition affects results of treatment by laser. In a clinical multicenter study, a mid-infrared, solid-state, pulsed-wave laser (holmium:YAG, 2.1 microns wavelength, 250-600 mJ/pulse, 5 Hz) was applied for revascularization of de novo and restenosis coronary lesions. Analysis of data was undertaken to document laser success, complications, and restenosis rate and to define whether the type of lesion treated had an effect on laser success and related complications. A total of 1340 patients with 1465 stenoses presented with symptomatic coronary artery disease. Laser success was 87 and 86% in these lesions, respectively. Overall procedural success of 93% was achieved. Restenosis lesions, known to be composed of smooth muscle proliferation, needed more laser energy for ablation than de novo lesions, which contain an atherosclerotic plaque (130 +/- 123 pulses vs 109 +/- 31, p = 0.001). Procedure-related Q-wave myocardial infarction was significantly higher in patients with de novo lesions over patients with restenosis lesions (1.4 vs 0.2%, p = 0.05). With the mid-infrared, pulsed-wave, holmium:YAG laser, the composition of the target lesion affects the energy level required, as well as the procedure-related complications.

Aged↗
PubMed1995

Efficacy of preconditioning with intracoronary diltiazem in preventing laser-induced spasm.

Laser energy produces a multitude of effects, resulting both in therapeutic tissue ablation and complications such as laser-induced spasm (LIS). LIS can occur during lasing itself or during subsequent adjunctive angioplasty. Intracoronary diltiazem (ICD) can partially reverse LIS after it occurs. To determine whether pre-treatment with ICD might prevent LIS during laser interventions, 3 groups of 50 lesions each were studied. Group 1 served as controls receiving no ICD during the procedure. Group 2 received 2.5 mg ICD before lasing. Group 3 received ICD before lasing and then a second infusion of 2.5 mg ICD after lasing but before adjunctive therapy. There were no differences in clinical characteristics of the 3 groups. Over 75% of lesions in each group were complex (B2 or C) lesions, and average lesion length was 15 mm in all 3 groups. Procedural success was > or = 94% in all groups. There was no significant difference among groups in pre-procedure artery stenosis, post-procedure stenosis, laser power used or number of laser pulses delivered. Pretreatment with ICD produced vasodilation of the minimum lumen diameter from 0.86 +/- 0.1 to 1.0 +/- 0.1 mm (p < 0.01) and was well tolerated. Control patients exhibited a 12% incidence of LIS. Group 2 had an 80% reduction of LIS during lasing (p < 0.01) but had increased LIS during adjunctive therapy with the same 12% incidence of LIS overall. Group 3 had only a 2% incidence of LIS (p < 0.01). We concluded that pretreatment with ICD significantly reduces LIS. Multiple infusions of ICD are necessary to sustain this protective effect.

Adult↗