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O Topaz

Publications and source records attributed to O Topaz.

At least 37 records · Page 2Linked to original sources
PubMed1998

Application of solid-state pulsed-wave, mid-infrared laser for percutaneous revascularization in heart transplant recipients.

BACKGROUND: Severe allograft coronary artery disease is a significant cause of death in heart transplant recipients. Percutaneous revascularization has thus far been attempted with balloon angioplasty and, to a lesser extent, with directional atherectomy. The new, investigational, solid-state pulsed-wave mid-infrared laser (holmium:YAG) can vaporize and remove atheromatous and thrombotic plaques. This mechanism of plaque ablation may be useful for allograft coronary artery disease associated with focal stenoses deemed unsuitable for standard balloon angioplasty, especially thrombus-containing lesions. METHODS: Five adult heart transplant recipients with severe focal stenoses related to allograft coronary artery disease underwent six laser angioplasty procedures. Laser catheters (2.1 microm, 250 to 600 mJ, 5 Hz) varying from 1.2 mm to 2.0 mm delivered 45 +/- 7.4 pulses (mean +/- SD). Five laser procedures were completed with adjunct balloon angioplasty and one with directional atherectomy. RESULTS: Laser success (defined as stenosis reduction > 20%, no cardiac catheterization laboratory or in-hospital major complication) was achieved in six of seven lesions (85%), and the overall (laser and adjunct balloon) procedural success rate was 100%. No major complications occurred. Laser-assisted angioplasty reduced mean stenosis from 90% +/- 3% to 9% +/- 11%. All five patients recovered and were discharged. Angiographic follow-up demonstrated a 50% restenosis rate. CONCLUSIONS: In selected heart transplant recipients laser-assisted angioplasty can provide safe and successful acute revascularization. Focal lesions considered "nonideal" for balloon angioplasty and, in particular, thrombotic lesions can benefit from application of this device; however, long-term reduction of restenosis rates is not expected from this modality.

Adult↗
PubMed1997

Anatomic variant of the posterior interventricular coronary artery: implications for coronary angioplasty in acute myocardial infarction.

Acute thrombotic occlusion of an infarct-related artery is frequently found in patients presenting with myocardial infarction. In a patient with acute inferior wall myocardial infarction complicated by continuous chest pain and hemodynamic instability, emergency diagnostic coronary arteriography demonstrated a patent, infarct-related, "pseudo" right coronary artery while, in fact, this vessel was a rare anatomic variant of the posterior interventricular branch with very early origin from the right coronary artery and the true right coronary artery was completely occluded by a thrombotic obstruction. Accurate anatomic-angiographic interpretation of the angiogram was crucial for successful performance of emergency recanalization and revascularization of the true right coronary artery with laser and balloon angioplasty. Once antegrade flow was restored another rare coronary variant was discovered, i.e., a sinoatrial node artery arising from the middle portion of the newly patent right coronary artery.

Adult↗
PubMed1997

Cardiac trauma. Diagnosis, management, and current therapy.

In cardiac trauma the two main mechanisms of injury are blunt and penetrating trauma. Common cardiac effects of trauma include myocardial rupture, contusion, laceration, pericardial insult, coronary injury, valvular damage, arrhythmias, and conduction abnormalities. Hemodynamic instability can develop rapidly and pose marked risk to patient survival. An adequate level of clinical awareness and timely use of diagnostic techniques such as echocardiography, aortography, and cardiac angiography are essential for rapid identification of cardiac trauma. Once the diagnosis is made, prompt surgical intervention is often the key to survival.

Coronary Vessels↗
PubMed1996

Solid-state mid-infrared laser facilitated coronary angioplasty: clinical and quantitative coronary angiographic results in 112 patients.

BACKGROUND AND OBJECTIVE: Holmium:YAG is a solid-state, investigational coronary laser device. Preliminary reports indicate the clinical potential for this laser; however, its safety and efficacy in a single center experience have not yet been reported and analyzed in detail. STUDY DESIGN, PATIENTS, AND METHODS: One hundred and twelve consecutive symptomatic patients underwent percutaneous holmium:YAG laser (2.1 micron wavelength, 250-600 mJ/pulse, 5 Hz) facilitated coronary angioplasty. Sixty-six patients (Gr 1) had 74 thrombotic lesions, and 46 patients (Gr 2) had 55 thrombus-free stenoses. RESULTS: Overall laser success was achieved in 120 out of 129 lesions (93%), with 95% subsequent balloon angioplasty success. Laser and clinical successes among the two groups were similar. By quantitative coronary angiography, reduction in the percent diameter stenosis (mean +/- SD) was similar (79 +/- 16% to 37 +/- 14% vs. 73 +/- 16% to 37 +/- 11.5%; P = NS) in both groups. However, minimal luminal diameter improved significantly more in Gr 1 patients, (0.7 +/- 0.5 mm to 2.0 +/- 0.5 mm, vs. 0.9 +/- 0.4 mm to 1.8 +/- 0.4 mm, P = 0.03). Angiographic and clinical complications were similar in patients with thrombus and without thrombus. No death, perforation, or Q-wave infarction occurred in the catheterization laboratory in either group. In-hospital mortality occurred in two patients from cardiac causes unrelated to the laser application. Of the 98 patients who reached the 6 month anniversary, 76 (77%) remained asymptomatic. The restenosis rate among the patients who underwent repeat angiography was 50%. CONCLUSIONS: Solid-state, mid-infrared laser can be safely and successfully applied to symptomatic patients with thrombotic and nonthrombotic lesions. Similar to other debulking devices, the effectiveness of this laser in yielding long-term patency has not been proved.

Adult↗
PubMed1996

The stenotic stent: mechanisms and revascularization options.

As demonstrated by the two recent randomized studies of elective, single stent placement versus balloon angioplasty of de novo lesions in the coronary arteries, angiographic restenosis occurs significantly less after stent implantation. However, reported stent restenosis rate varies from 14% to more than 60%, depending on patient characteristics, stent design, number of stents implanted, vessel treated, location of the lesion, and acute luminal gain. The lowest rate of stenosis occurs in de novo lesions. The highest rate of stent restenosis is encountered in multiple stents and in ostial saphenous vein graft lesions. Stent restenosis can be treated with balloon angioplasty with very high success rates. This treatment is associated with remarkably low incidence of complications. Focal stenoses within the stent are more easily treated than are diffuse occlusions. Atherectomy of intrastent stenosis is not recommended. Excimer and holmium: YAG lasers can be applied for revascularization of intrastent lesions considered "not ideal" for balloon angioplasty. Unless thrombus is present or significant dissection detected or angioplasty performed within 2 months following stenting, patients do not require anticoagulants following balloon angioplasty of stent restenosis.

Angioplasty, Balloon, Coronary↗
PubMed1996

Anomalous first septal perforator artery: anatomic-clinical correlates.

The interventricular septum is considered the most densely vascularized portion of the heart, containing important elements of the cardiac conduction system and providing mechanical support for both right and left ventricular function. Anatomically, this structure is perfused by the relatively small caliber anterior and posterior septal perforator branches arising from two large epicardial coronary vessels, the anterior interventricular (descending) branch of the left coronary artery and the posterior interventricular (descending) branch of the right coronary artery, respectively. In cases of significant atherosclerotic disease depriving flow in the major coronary vessels and their septal branches, an anomalous septal perforator artery can take over the task of supporting the function of the interventricular septum by supplementing essential collateral flow.

Aged↗
PubMed1996

Photoacoustic Fibrinolysis: Pulsed-Wave, Mid-Infrared Laser-Clot Interaction.

Objectives: The purpose of this study was to determine whether a mid-infrared laser can induce selective fibrinolysis and to analyze the effect of altered fibrin structure (thin vs. thick fibers) on laser-clot interaction. Background: Mechanical disruption of thrombus can be achieved with balloon angioplasty, sonication, and thermal energy. Thrombi avidly absorb light in the mid-infrared optical spectrum due to their high water content. This phenomenon provides a potential for mid-infrared lasers as a source for selective thrombolysis. As fibrin is the essential component of clot, a study of mid-infrared laser-fibrin interaction is warranted. Methods: Clots of varying fibrin structure were lased in cuvettes with a solid-state, pulsed-wave, mid-infrared laser (2.1 micron, 500 mJ/pulse, 250 msec pulse length). Total pulse energies of 5 Joules (J), 10 J, 37.5 J, 75 J, and 112.5 J were tested. Protein content of the extruded fluid was measured by optical density absorbance at 280 nm. Th e amount of released material was studied as a function of lasing energy and clot structure. SDS-polyacrylamide gel electrophoresis was applied for analysis of protein bands in order to identify unique protein bands released by the selective effect of laser fibrinolysis. Results: A threshold for mid-infrared laser induced fibrinolysis was found; application of up to 20 J of energy did not result in dissolution. As lasing energy was increased above 37.5 J, the structure of these gels was mechanically destroyed and 12.4 +/- 6.7% (mean +/- SEM) of the original content of protein was released. Electrophoresis revealed that lased gels did not release any unique protein band. Lased, thin fibers released significantly less protein than thick fibers, indicating that they are more resistant to the effect of this wavelength of energy. Conclusions: Mid-infrared laser can induce in-vitro photoacoustic dissolution of fibrin clots. However, this wavelength laser achieves fibrinolysis by me chanical destruction of the target clot rather than by a selective effect, as induced by the pulsed-dye laser. A threshold exists for energy levels required. Thin fibrin fibers, with their high elastic modulus (i.e., gel rigidity) appear more resistant than thick fibers to the effect of lasing at this wavelength.

Journal Article↗
PubMed1996

Holmium laser angioplasty.

The investigational solid-state, pulsed-wave, mid-infrared (2.1 microns) holmium:YAG laser can be applied for plaque ablation and thrombus dissolution. A multicentre study reports 87% laser success and 94% final procedural success. It has established the safety and efficacy of this laser in ischaemic syndromes and acute myocardial infarction treating lesions considered 'not ideal' for balloon angioplasty. These include thrombotic occlusions, total occlusions, calcified obstructions, de novo and restenosis lesions within native coronary arteries and saphenous vein grafts. Unfortunately, the laser does not significantly reduce restenosis rate. Processes related to laser-tissue interactions such as gas vapour formation and generation of acoustic waves with tremendous intraplaque pressures mandate application of appropriate lasing technique to ensure clinical success.

Aged↗
PubMed1995

Laser for optical thrombolysis and facilitation of balloon angioplasty in acute myocardial infarction following failed pharmacologic thrombolysis.

This report discusses a new indication for the use of holmium:YAG laser. It includes facilitation of thrombolysis and plaque ablation in acute myocardial infarction after failure of thrombolytic agents. Further study is required to define optimal utilization and integration of this novel device for patients who fail to respond to thrombolytic agents.

Angioplasty, Balloon, Laser-Assisted↗
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↗