Laser-induced fluorescence emission: I. The spectroscopic identification of fibrotic endocardium and myocardium (original) (raw)
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Time-resolved fluorescence spectroscopy of the heart tissues
Lithuanian Journal of Physics, 2011
During the heart surgery there is a possibility to harm the conduction system of the heart (HCS), which may cause dangerous obstruction of the heart functionality. The muscular origin makes it complicated to distinguish HCS from the surrounding tissues; therefore, there is an immense necessity to visualise HCS during the operation time. Optical methods carry information about intrinsic properties of the tissue and provide the unique possibility to study the objects non-invasively. The experiments were performed on the human heart tissue specimens ex vivo. HCS, myocardium (MC), and connective tissue (CT) were preliminary marked by a pathologist and histologically approved after the spectral measurements. The spectrometer FLS920 (Edinburgh Instruments) was used for steady state and time-resolved fluorescence registration. Fluorescence was exited using a 405 nm pulsed laser. Spectral analysis revealed that at least three fluorophores are responsible for the emission in the region of 430-550 nm. According to the lifetimes, the fluorescing constituents in all tissues should be the same. The fractional components of fluorescence intensity revealed a similar composition of MC and HCS; however, quantitative differences were observed between HCS and CT.
Lasers in Surgery and Medicine, 1991
Laser photocoagulation of the myocardium effectively destroys arrhythmogenic foci. The purpose of this study was 1) to compare the optical properties of canine myocardium before and after photocoagulation, 2) to compare the canine model with clinical cases by measuring the optical properties of human myocardium, and 3) to assess the optical properties of human myocardial scar and epicardial fat tissue. Measured optical properties were the absorption coefficent, μa; scattering coefficient, μs; and scattering anisotropy factor, g. Optical measurements were performed at 1064 nm wavelength on thin plane parallel tissue slices using the integrating sphere method with glass hemispheres on either side of the sample. The study showed 1) an increase of the scattering coefficient by 40% and a two- to threefold increase in reduced scattering coefficient as a result of photocoagulation; 2) that the μa (0.035 ± 0.024 mm−1) and μs (17.9 ± 3.8 mm−1) of human myocardium were not significantly different from μa (0.043 ± 0.021 mm−1) and μs (17.3 ± 2.2 mm−1) of canine myocardium, whereas the human g (0.964 ± 0.005) was slightly different from the canine g (0.974 ± 0.008); and 3) that the μa (0.021 ± 0.016 mm−1) of epicardial fat and μs (13.8 ± 1.1 mm−1) of myocardial scar were significantly lower than those of normal myocardium. A dynamic model of laser-tissue interaction incorporating these changes and inhomogeneities is necessary to better describe light distribution during laser photocoagulation.
Laser–Tissue Interaction During Transmyocardial Laser Revascularization
Annals of Thoracic Surgery, 1997
Background. The clinical procedure known as transmyocardial revascularization has recently seen its renaissance. Despite the promising preliminary clinical results, the associated mechanisms are subject to much discussion. This study is an attempt to unravel the basics of the interaction between 800-W CO 2 laser radiation and biological tissue.
Journal of Photochemistry and Photobiology B-biology, 1994
In order to develop a reliable laser-induced-fluorescence-guided angioplasty system, fluorescence spectra were recorded during exposure of normal and atherosclerotic cadaveric aortic tissue to He-Cd laser radiation (442 nm). A characteristic increase in the fluorescence signal at 600 nm for atheromatous tissue was observed after treatment of the samples with hypocrellin (HA). This, combined with the spectra1 distribution of tissue natural fluorescence, allowed the development of simple algorithms, based on the intensity difference and the full width at half-maximum (FWHh4), and a subsequent index of discrimination between normal and various atheromatous tissues. Our results suggest that monitoring of this index through the catheter could enhance selective ablation, reducing the risk of normal vessel perforation. 139 loll-1344/94/$07.00 0 1994 Elsevier Sequoia. All rights reserved SSDI 1011-1344(93)06960-B
Histological Evidence of Angiogenesis 9 Months After Transmyocardial Laser Revascularization
Circulation, 2001
A 66-year-old white male with end-stage ischemic cardiomyopathy was referred to our center for transmyocardial laser revascularization (PLC Eclipse Surgical Technologies) in July 1999. The patient had a long history of interventions for his coronary artery disease, including multiple percutaneous transluminal coronary angioplasties, stent placement in 1991 and 1993, and coronary artery bypass grafting in 1987 and 1992. He was evaluated for a third bypass, but we determined he was not a suitable candidate because of his diffuse small vessel distal coronary artery disease. Given the limitations of conventional therapeutic options, the patient underwent transmyocardial laser revascularization in July 1999. Thirty transmural channels were lased in the ischemic anterior and lateral walls of the left ventricle. The patient tolerated the procedure well and received anginal relief for the following 6 months; he then experienced recurrent symptoms of angina and progressive cardiac failure. Stress thallium 201 imaging at that time demonstrated increased ischemic areas in the posterior and inferior myocardium, with improved perfusion in the previously lased anterior and lateral walls. His clinical situation continued to deteriorate, and he was listed for and subsequently received a heart transplant in March 2000. At that time, his native heart was explanted and examined for evidence of angiogenesis in the lased areas of myocardium.