PubMed Health⌕ Search

Biomedical subjects

L I Deckelbaum

Publications and source records attributed to L I Deckelbaum.

47 records · Page 3Linked to original sources
PubMed1988

Laser angioplasty.

Laser technology clearly offers new approaches to the treatment of cardiovascular disease. The ability to transmit intense laser energy through optical fibers may allow precise ablation of pathologic cardiovascular tissues. This potential has stimulated extensive research on laser vaporization of atherosclerotic plaque, or laser angioplasty. Despite the preceding several years of research, there is currently no widespread laser angioplasty system in clinical use. The goal of complete atherosclerotic plaque vaporization without damage to the underlying arterial wall still remains elusive. This article reviews multiple different approaches to the development of laser angioplasty systems. It is too early to predict if all (or any) of these systems will be perfected to the degree necessary to provide cardiologists with a safe and effective laser angioplasty system. It is also difficult to predict the effect that the technologically simpler mechanical recanalization devices and arterial stents will have on laser angioplasty development. Nevertheless, laser angioplasty remains an exciting and promising approach for intravascular recanalization by vaporization of atherosclerotic plaque.

Cardiovascular Diseases↗
PubMed1988

In vivo fluorescence of human skin. A potential marker of photoaging.

Fluorescence is a feature of elastin and collagen, both major compounds of human dermis that are altered by age and photoexposure. We studied the intrinsic fluorescence of skin in vivo in 28 human volunteers to determine whether photoaging and chronologic aging of the skin could be evaluated by this noninvasive technique. We demonstrate that the excitation of skin autofluorescence by laser ultraviolet radiation yields characteristic tissue fluorescence spectra that are unrelated to age, pigmentation, or skin thickness. The differences in skin autofluorescence appear to be related to photoexposure. Thus, laser-induced fluorimetry, a noninvasive technique, may be adaptable as a marker of photoaging.

Adult↗
PubMed1987

Discrimination of normal and atherosclerotic aorta by laser-induced fluorescence.

Precise targeting of laser energy to atherosclerotic plaque is crucial for the safe performance of laser angioplasty. The present study was designed to evaluate whether laser-induced fluorescence could distinguish atherosclerotic from normal aorta. Segments of human aorta obtained at necropsy were classified grossly and histologically as normal aorta (n = 7), thin yellow fatty plaque (n = 5), and thick white atheromatous plaque (n = 9), and analyzed by laser-induced fluorescence spectroscopy using a pulsed nitrogen laser. Fluorescence spectra were recorded over a wavelength range from 385 to 725 nm. Normal specimens had maximal fluorescence intensity at 514 nm. A prominent fluorescence peak at 448 nm was present in specimens characterized as white atheromatous plaque and at 538 nm in specimens characterized as yellow fatty plaque. The ratios of fluorescence intensity at 448 nm/514 nm and at 538 nm/514 nm correctly classified all specimens according to their gross and histologic type (p less than .001). Thus, a "smart" laser angioplasty catheter system might incorporate low-power laser radiation for arterial fluorescence spectroscopy to guide delivery of high-power laser radiation for plaque ablation.

Aorta↗
PubMed1986

Use of pulsed energy delivery to minimize tissue injury resulting from carbon dioxide laser irradiation of cardiovascular tissues.

The carbon dioxide (CO2) laser has been utilized for preliminary intraoperative cardiovascular applications, including coronary endarterectomy and ventricular endocardiectomy. CO2 lasers used for these applications have been operated in the continuous wave, chopped or pulsed mode at low peak powers. To evaluate the extent of boundary tissue injury, continuous, chopped and pulsed energy delivery of CO2 laser emission was used to bore through 192 5 mm thick myocardial slices in air. Continuous, chopped and pulsed delivery at a peak power of 500 W or less failed to eliminate light microscopic or ultrastructural signs of thermal injury. Only when a high energy CO2 laser (pulse energy 80 to 300 mJ, pulse duration 1 microseconds) was used at a peak power greater than 80 kW were all signs of thermal injury eliminated; furthermore, high peak power prevented thermal injury only when the beam was focused to achieve a peak power density greater than 60 kW/mm2. Under these conditions, pathologic findings were identical to those observed using excimer wavelengths. The results of these experiments indicate that: conventional CO2 lasers fail to minimize boundary tissue injury, elimination of thermal injury during intraoperative laser ablation requires that CO2 laser energy be focused to achieve a peak power density greater than 60 kW/mm2, and elimination of thermal injury can be achieved at a variety of wavelengths, provided that an appropriate energy profile is employed.

Carbon Dioxide↗
PubMed1985

Reduction of laser-induced pathologic tissue injury using pulsed energy delivery.

Continuous-wave (CW) laser irradiation of cardiovascular tissues is characterized by 2 distinctive histologic findings: a superficial zone of coagulation necrosis and a subjacent zone of polymorphous lacunae. The present investigation was designed to determine whether such injury could be eliminated by altering the temporal profile of laser energy delivery. One hundred forty-five myocardial slices were irradiated with an air-tissue interface using CW laser irradiation at wavelengths of 488 to 515 nm (argon), 1,064 nm (Nd-YAG) and 10,600 nm (CO2). Pulsed laser irradiation included 248 nm (excimer); 355, 532 and 1,064 nm (Nd-YAG); and 515 nm (mode-locked argon). Energy profiles in the pulsed mode included a range of repetition rates (1 Hz to 256 MHz), pulse duration (0.2 to 358 ns) and pulse energies (2 nJ to 370 mJ). Resultant average powers were 0.1 to 38 W. Grossly visible charring of myocardial tissue was observed at all laser wavelengths when the laser energy profile was CW or pulsed at high repetition rates (more than 2 KHz) and low pulse energies (less than 3 mJ) independent of the wavelengths used. In contrast, when laser energy was pulsed at low repetition rates (less than 200 Hz) and large pulse energies (more than 10 mJ), neither gross nor histologic signs of thermal injury were observed. Pathologic injury associated with laser-induced tissue ablation may thus be substantially reduced by use of pulsed energy delivery at low repetition rates. Potential advantages of pulsed laser energy include a more benign healing process, a less thrombogenic surface, and improved preservation of structural tissue integrity.

Animals↗
PubMed1985

The excimer laser: gross, light microscopic and ultrastructural analysis of potential advantages for use in laser therapy of cardiovascular disease.

Excimer lasers are pulsed gas lasers that use a mixture of a rare gas and halogen as the active medium to generate pulses of short wavelength, high energy ultraviolet light. A krypton-fluoride gas mixture was used to achieve an excimer emission at a wavelength of 248 nm. A total of 30 atherosclerotic coronary artery segments were irradiated over a range of pulse energies (250 to 750 mJ), repetition rates (2 to 25 Hz), average powers (1.9 to 18.8 watts) and cumulative exposures (3 to 12 seconds). In no case was there gross, light microscopic or ultrastructural evidence of the pathologic injury typically associated with continuous wave laser irradiation of coronary artery segments. Similar results were achieved after excimer laser irradiation of 30 samples of myocardium. Excimer irradiation of calcified aortic valve leaflets accomplished focal debridement without pathologic tissue injury; when total debridement was attempted, however, gross charring was observed. The paucity of pathologic alterations observed after excimer irradiation of cardiovascular tissue may prove beneficial in precisely controlling laser ablation of pathologic tissue without injury to the surrounding normal tissue. Clinical application of excimer laser irradiation requires resolution of several issues, including the development of suitable fiber optics and laser coupling, evaluation of potential ultraviolet toxicity, and demonstration that ultraviolet light can be transmitted through a blood-filled system.

Coronary Disease↗
PubMed1985

Factors contributing to perforations resulting from laser coronary angioplasty: observations in an intact human postmortem preparation of intraoperative laser coronary angioplasty.

This investigation was designed to assess the potential use of laser coronary angioplasty as an intraoperative adjunct in the surgical treatment of ischemic heart disease. Among 17 postmortem hearts, simulated laser coronary angioplasty was performed at 53 sites with a No. 4F guiding catheter and 240 micron (200 micron core) quartz optical fiber. Perforation complicated laser coronary angioplasty in 33 (62%) of the 53 attempts. Most (n = 29) perforations were thermal; four were purely mechanical. Perforation sites were characterized by extensive calcific deposits (21 of 33 cases [64%] ) and the origin of a side branch (13 of 33 [39%] ). Excessive tortuosity of the extramural coronary artery contributed to arterial perforation in four cases, and precluded attempts to perform laser coronary angioplasty in two other cases. In 19 of the 53 attempts to perform laser coronary angioplasty, a high-frequency two-dimensional echocardiographic probe was used to image the coronary artery during antegrade manipulation of the optical fiber/guiding catheter and laser irradiation of the target arterial stenosis. Although perforation nevertheless occurred in 11 (58%) of 19 sites, only one mechanical perforation resulted; the remaining 10 were thermal. Characteristics of the perforation sites in this group were similar to those noted for the group as a whole. Experience with this model of laser coronary angioplasty indicates that even when access problems associated with percutaneous laser coronary angioplasty are obviated by a simulated intraoperative approach, perforation of the underlying coronary arterial wall continues to represent the "rate-limiting" complication of laser coronary angioplasty. Most perforations occurred in relation to calcific deposits, branch points, and tortuous coronary segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Severe regional ischemia alters coronary flow reserve in the remote perfusion area.

BACKGROUND: Clinical and experimental studies suggest that coronary flow reserve (CFR) may be abnormal in regions remote from myocardial infarction. We sought to determine the possible relation among stenosis severity, ischemic dysfunction, and impairment of CFR in remote regions. METHODS AND RESULTS: In 7 open-chest dogs, acute graded left circumflex (LCX) ischemia was created and maintained based on measurement of the transstenotic (aortic-distal LCX) pressure gradient (measured in millimeters of mercury). Regional thickening was assessed with sonomicrometers. Regional myocardial flow was assessed at rest with radiolabeled microspheres. Doppler flow probes were placed on proximal LCX and left anterior descending (LAD) arteries to measure resting flow and CFR in response to intracoronary injection of adenosine (36 microg). These parameters were assessed under baseline conditions and during transstenotic gradients of 10, 20, 30, and 40 mm Hg. Increasing LCX stenosis severity caused progressive impairment of LCX CFR: baseline (2.22+/-0.10), stenosis 10 (1.80+/-0.06), stenosis 20 (1.56+/-0.08), stenosis 30 (1.30+/-0.04), and stenosis 40 (1.17+/-0.06) (P<.01 vs. baseline). Remote LAD CFR was not altered by mild to moderate LCX stenosis (baseline [2.33+/-0.19]; stenosis 10 [2.30+/-0.25]; stenosis 20 [2.15+/-0.26]). However, critical LCX stenosis producing mild to moderate reduction in thickening in the ischemic region was associated with a significant impairment of LAD CFR: stenosis 30 (1.90+/-0.26) and stenosis 40 (1.80+/-0.22) (P<.01 vs. baseline). These changes in remote CFR persisted after correction for changes in the rate-pressure product. CONCLUSION: In an acute canine model of progressive LCX coronary stenosis, CFR was impaired in both ischemic and remote nonischemic regions in association with mild to moderate ischemic-induced regional myocardial dysfunction. Thus pharmacologic vasodilation provoked only mild heterogeneity in CFR in the presence of a critical LCX stenosis as a result of concurrent reduction of LAD CFR. This phenomenon warrants further clinical and experimental investigation because it may affect detection of flow heterogeneity during acute ischemia (which induced myocardial dysfunction).

Adenosine↗