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Biomedical subjects

R L Reis

Publications and source records attributed to R L Reis.

At least 73 records · Page 4Linked to original sources
PubMed1985

Argon laser radiation of human clots: differential photoabsorption in red cell rich and red cell poor clots.

Since argon laser radiation (454-514 nm) can vaporize human clots, we determined whether the absorption of laser energies can differ among different types of blood clots. Thus we performed spectrophotometric studies and examined the ability of this laser to penetrate red cell rich and red cell poor clots. Fifty-four red cell rich and red cell poor clot samples, varying in depth from 1.8 to 5.0 mm, were subjected to 3, 5 and 7 watts from an argon laser beam. At a given power intensity, the deeper the red cell rich clot, the longer was the time needed to penetrate the clot. The higher the power used, the shorter was the red clot penetration time. In contrast, all power levels used up to 5 minutes did not penetrate any of the varying depths of red cell poor clots. Spectrophotometrically, the red cell rich clot had an absorption curve typical of hemoglobin pigment while the red cell poor clot, in the absence of hemoglobin, had poor absorption between 350 and 600 nm and was unable to absorb argon laser energies. Thus, the argon laser provides a therapeutic modality for human red cell rich clot dissolution but the present approach does not appear to be effective against red cell poor clots.

Blood Coagulation↗
PubMed1985

Applicability of laser to assist coronary balloon angioplasty.

Severe atherosclerotic obstructed coronary artery disease (CAD) may preclude passage of a balloon catheter for transluminal coronary angioplasty (TCA). Since lasers have been shown to effectively vaporize CAD plaque, the initial application of laser to effect a lumen large enough to accommodate the angioplasty catheter for further dilatation was explored. Eleven postmortem human CAD segments which did not permit passage of a 1.33 mm shaft diameter angioplasty catheter were studied. Argon laser radiation (14 to 90 J) transmitted via 400 micron core diameter quartz fiber onto the stenotic channel of 0.58 mm created a vaporized lumen of 1.77 mm (mean increase of 1.31 +/- 0.25 mm, p less than 0.001). The laser procedure allowed the balloon angioplasty catheter to be pushed into the stenosis. TCA was then performed (7 atm, 45 seconds) and expanded the channel to 2.12 mm (additional mean increase of 0.38 +/- 0.07 mm, p less than 0.001). In terms of percent luminal narrowing, laser radiation reduced obstruction from 80% to 45% (mean difference of -38.7 +/- 4.6%, p less than 0.001), and TCA caused a further decrease to 37% (mean difference of -9.3 +/- 1.9%, p less than 0.001). Thus, in tight atherosclerotic lesions, the laser may be useful in creating an initial opening enabling the placement of the balloon angioplasty catheter which, in turn, can further dilate the lased stenotic coronary lumen.

Angioplasty, Balloon↗
PubMed1985

Laser therapy of coronary artery obstructions.

Laser energies can be transmitted through flexible optical fiber to vaporize and penetrate coronary atherosclerotic and thrombotic obstructions. There are risks and complications involved in this therapy, however, including perforation, aneurysm formation, and thromboembolic risks, and further research is needed to render the laser recanalization procedure safe.

Angioplasty, Balloon↗
PubMed1984

Intraoperative use of dual fiberoptic catheter for simultaneous in vivo visualization and laser vaporization of peripheral atherosclerotic obstructive disease.

Since laser energy has been shown to produce controlled thermal injury to atherosclerotic plaques from postmortem human hearts, a 3-mm diameter fiberoptic catheter was devised and tested for use in peripheral vessels. The catheter has channels for viewing, laser delivery, and suction/flushing. In five femoral or carotid arteries from three dogs implanted with near-total human atherosclerotic obstructions, the fiberoptic catheter was capable of viewing and targeting the atherosclerotic plaque for laser irradiation. The plaque was vaporized using 5 watts with time exposures lasting from 2 to 5 sec from an argon-ion laser. In three other animals each implanted with a 3- to 4-cm long segment of human cadaver atherosclerotic vessel, the fiberoptic catheter clearly visualized the internal diseased vascular wall. Thus, this investigation provides the initial demonstration and practicality of applying a flexible dual fiberoptic catheter for simultaneous in vivo visualization and laser vaporization of peripheral atherosclerotic disease.

Animals↗
PubMed1984

Dissolution of pulmonary carcinoma via argon-laser bronchoscopy. First clinical use of fiberoptic metal cautery cap heated by laser radiation.

A 60-year-old man with nonresectable lung cancer underwent bronchoscopy which revealed a large squamous cell tumor mass narrowing the free airway to the left lung. A flexible quartz fiber connected to an argon ion laser was then inserted through a hollow channel of the fiberoptic bronchoscope. The laser was activated to heat the metal cap on the distal tip of the fiber to thermally dissolve the mass and relieve airway obstruction.

Argon↗
PubMed1984

Effects of laser radiation on the morphology of human coronary atherosclerotic disease.

Laser energy delivered through optical fibers can produce potent controlled thermal dissolution of human coronary obstructive disease, thus widening the stenotic vascular lumen. The ease of vaporization and penetration depends not only on the physical properties of the laser beam but also on the physical characteristics of the atherosclerotic plaque. Lipid-laden plaques are more easily vaporized compared with plaques that are heavily calcified. In atherosclerotic animal models studied in vivo, laser radiation produced a charred lining around the evacuated area and rapid regeneration of a new endothelial lining. After several weeks, the laser-induced crater was still evident, and thrombogenesis was not a significant complication. Focal aneurysmal dilatation may develop when there is thermal injury of the medial layer, and acute perforation can occur if severe laser burn is extended beyond the adventitial layer. Further technical advances and achievements are needed before laser recanalization becomes a clinical reality.

Animals↗
PubMed1983

Effects of laser irradiation on human thrombus: demonstration of a linear dissolution-dose relation between clot length and energy density.

Because vascular thrombosis often accompanies arteriosclerotic disease in occluding blood vessels, the dissolution properties of laser irradiation were investigated and the energies needed to penetrate different lengths of thrombus were quantitated. Spectrophotometric studies show that the blood clot due to the presence of hemoglobin is well absorbed by argon laser energies, which emit blue-green wavelengths between 454 and 514 nm. Thus, laser energies transmitted directly from an argon-ion source produced vaporization and penetration of human thrombus in a linear dose-response fashion; the longer the thrombus, the greater the power intensity or time exposure necessary to penetrate the clot.

Dose-Response Relationship, Radiation↗
PubMed1983

Laser irradiation of congenital heart disease: potential for palliation and correction of intracardiac and intravascular defects.

We examined the potential for laser irradiation of congenital heart defects, with the use of postmortem hearts and an argon ion laser with a flexible quartz fiber. Atrial septectomy was performed in five newborn hearts. Obstructive lesions were relieved by laser irradiation in valvular pulmonic and aortic stenosis, dysplastic pulmonary valve, pulmonary atresia, and coarctation of the aorta. To demonstrate the efficacy of in vivo cardiac laser surgery, atrial septectomy was also performed in an anesthetized dog model, under echocardiographic visualization, without change in heart rate or blood pressure. Our results demonstrate the feasibility of intracardiac and intravascular laser irradiation for palliation and repair of selected congenital heart diseases.

Animals↗