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Biomedical subjects

D Stobbe

Publications and source records attributed to D Stobbe.

13 recordsLinked to original sources
PubMed1984

Acute and chronic complications of laser angioplasty: vascular wall damage and formation of aneurysms in the atherosclerotic rabbit.

Acute and chronic vascular responses to laser exposure in atherosclerotic rabbits were studied. In 7 rabbits fed an atherogenic diet for 3 to 5 months before the study to induce aortic atherosclerosis, a flexible quartz fiber, 400 micron core diameter, attached to an argon ion laser was passed anterogradely or retrogradely to the atherosclerotic ascending aorta. The laser was turned on using power intensities of 1 to 2 W for 3 seconds. After laser treatment, the aortas were studied acutely in 3 rabbits and chronically in 4 rabbits after recovery for 1 to 14 days. In 2 rabbits studied acutely, the argon laser produced a vaporized crater within the atherosclerotic plaque at the endothelial surface; however, in 1 there was also vascular damage extending deep into the medial layer. In addition, aortic aneurysm with muscular wall damage occurred in 2 of the 4 animals studied chronically. Thus, vascular complications may arise when catheter laser angioplasty is randomly applied without visualizing specific plaque targets or without using safe dose increments of power intensities and durations of exposure. This study suggests caution in the clinical use of intensive phototherapy to cardiovascular lesions and stresses the need for further understanding of laser vascular consequences before application of laser angioplasty in patients.

Animals↗
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↗
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

Effects of laser irradiation on human erythrocytes: considerations concerning clinical laser angioplasty.

Recent studies demonstrate the potential use of laser to vaporize human coronary atherosclerotic plaques. The laser energy is transmitted through flexible quartz fiber and discharged intravascularly. Since red blood cells could be exposed to intense heat, we examined effects of laser irradiation on human erythrocytes. Blood was obtained and placed in 5 ethylene diaminetetracidic acid (EDTA) vials for each normal donor. A flexible 400 microns diameter core quartz fiber coupled to an argon-ion laser source was positioned 1 cm above the surface of 1.5 ml blood. Four vials were exposed to 5 W laser beam for 5, 10, 15, or 20 s; the remaining vial was left untreated. Packed cell volume fell primarily during the first 5 s of laser exposure (p less than 0.01) and plateaued beyond 5 s. Plasma hemoglobin (Hgb) rose progressively with each increased duration of exposure (p less than 0.01). This study indicates that lysis of erythrocytes occurs in cells exposed directly to the laser beam. However, beyond the direct beam, damage to red cell membrane took place as evident by progressive Hgb leakage into plasma despite no further cell lysis. These observations require consideration during clinical laser angioplasty.

Erythrocyte Indices↗
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↗