Eosinophilia in the diagnosis of atheroembolic renal disease

James S. T. Yao, MD, Abstracts

Section Editor

Eosinophilia in the diagnosis of atheroembolic renal disease Kasinath BS, Corwin HL, Bidani AK, et al. Am J Nephrol 1987;7:173-7. Atheroembolism can affect the circulatory bed of any organ. The condition is usually seen in elderly ad&s with extensive atherosclerotic vascular disease and commonly appears with livedo reticularis and progressive renal insufficiency. Although atheroembolism can occur spontaneously, it frequently occurs after angiography of aortic surgery. In the past, diagnosis has depended on organ biopsy (e.g., skin, muscle, or kidney) showing cholesterol emboli in small arteries. This article emphasizes that eosinophilia is another helpful clue to atheroembolic renal disease. In a small group of six of their own patients and a review of 36 patients in the literature, the authors noted eosinophilia in 80% of documented cases of renal atheroembolism. In contrast, only 2.5% of patients with acute renal failure from other causes have eosinophilia. During the course of renal atheroembolism, the eosinophilia fluctuated. The differential eosinophilic count ranged from 5% to 16%. Eosinophilia did not correlate with either the course of renal failure or with any administered drugs. Renal biopsies did not reveal eosinophilic infiltration of the parenchyma, and the urine did not contain eosinophils. It is not clear whether renal atheroembolism is a prerequisite for the appearance of eosinophilia or if it occurs when emboli involve other vascular beds. The eosinophilia may be related to activation of complement component CSa, which is known to be chemotactic for eosinophils. Incubation of pure cholesterol crystals, human atheromatous material, and normal plasma enhances the capacity of serum to cause aggregation of polymorphonuclear let&ocytes and injury to endothelial cells in cukure. These events have been attributed to the generation of C5a and could explain eosinophiha and endotheIia1 injury in atheroembolism. John W. Hallett, Mayo Clink

JY., MD

Laser probe ablation of normal and atherosclerotic human aorta in vitro: a first thermographic and histologic analysis Welch AJ, Bradley AB, Torres JH, et al. Circulation 19&7;76:1353-63. These authors, from the Department of Electrical and Computer Engineering of the University of Texas, have provided the first thermographic and histologic analysis of laser tissue ablation. This study was designed to analyze the thermal characteristics of the laser probe, comparing it with direct laser irradiation, and to measure the tempera654

ture changes and histologic damage produced by the heated probe on normal and atherosclerotic tissue. The experiments were carried out on specimens of human aorta, both normal and atherosclerotic. Argon ion lasers were used to either heat a metal probe or to directly irradiate the tissue. Laser probe temperatures were determined by both a thermocoup!e and thermography. Tissue temperatures were determined by thermography. The aortic specimens were inspected histologically after laser treatment. These studies revealed the folIowing: (1) Probe temperature increased almost linearly with delivered laser power and decreased as the thermal conductivity of the surrounding media increased. Probe and tissue temperature increased linearly with exposure time. (2) Tissue ablation occurred at temperatures exceeding 180” C. Probe temperatures consistently exceeded tissue temperatures; however, temperatures in excess of 50” C, a level at which irreversible denaturation of proteins can occur, persisted at distances greater than 1.0 mm from the probe. (3) Ablation of atherosclerotic tissue was greater than ablation of nonatherosclerotic tissue under the same circumstances. (4) Increasing the force applied to the probe increased tissue ablation. (5) The bare fiber laser produced greater tissue ablation than the hot probe under similar circumstances. (6) Direct irradiation of nonatherosclerotic aorta resulted in tissue fragmentation and subintimal dissections, not seen with the laser probe. This study is of great interest to those physicians who use, or intend to use, laser devices in the treatment of atherosclerotic disease. Although the long-term effect of the laser on Iiving arterial tissue is stitl unknown, this study does provide useful information as to the thermal characteristics of the laser ablation process. It appears as though the laser probe produces tissue ablation in a controlled manner with a uniform conduction of heat and without the extensive subintimal dissections seen with the bare fiber laser. Tissue ablation may be increased by increasing the energy applied to the probe, the time the tissue is exposed to the probe, or the force with which the probe is applied to the tissue. The authors also noted the lateral spread of the thermal injury and emphasized the importance of not allowing the probe to remain in stationary contact wirh the vessel wall for a prolonged period, thereby avoiding uncontrolled lateral and transmural conduction of heat. Cornelius Stassfozf

Olcott IV, MD Univmity Medical

Center

Carnitine metabolism during exercise in patients with peripheral vascular occlusive disease Hiatt WR, Nawaz D, Brass EP. J Appl Physiol 1987; 62:2383-7. This article studies abnormalities in the oxidation of free fatty acids in the skeletal muscle of patients with pe-