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While the cellular mechanisms of atherosclerosis have been intensively studied, the mechanisms leading to preferential localization of atherosclerotic lesions are less well understood. To further define these mechanisms, endothelial cells from coronary arteries, i.e., vessels with frequent atherosclerotic lesions, were isolated and grown in vitro. In order to compare the reactions of both cell types, endothelial cells derived from microvessels of human hearts were isolated and cultured under identical conditions. Incubation of endothelial cells with oxidized LDL (75 microg/ml protein) induced a significant increase in PAI-1 activity (182%, p < 0.05) in coronary macrovascular endothelial cells. This stimulatory effect of ox-LDL was less significant in microvascular endothelial cells (144%, p < 0.05). n-LDL did not influence secreted PAI-1 activity. Stimulation with angiotensin II induced expression of E-selectin more effectively in coronary macrovascular than in microvascular endothelial cells. In addition, angiotensin II-induced E-selectin expression led to increased E-selectin-dependent adhesion of HL60 cells to coronary macrovascular endothelial cells under flow conditions, while only little effect was observed with cardiac microvascular endothelial cells. In contrast, L-selectin-dependent adhesion, which has been shown to play an important role in inflammatory reactions, was preferentially observed in cardiac microvascular endothelial cells and could only be stimulated with TNFalpha, not by angiotensin II. Therefore, these cellular differences may in part explain specific properties of cardiac endothelial cells: Such that atherosclerotic lesions are localized in macrovascular vessel segments, whereas inflammatory responses are predominantly found in the microvasculature.

To deal with the problem of restenosis after PTCA, several new methods and devices for treating atheromatous lesions have been developed. Among the promising techniques, is the opportunity to remove atheromatous material with the directional coronary atherectomy catheter designed by J.B. Simpson. The atherectomy catheter consists of a housing at the catheter tip with a concave cutting device which is rotated at a speed of 2000 r.p.m. The housing is positioned at the stenosis by means of a central guidewire; the material to be removed protrudes into the housing. With an inflatable balloon on the opposite side, the position of the housing is fixed in the coronary artery, the plaque is pressed further into the orifice and severed by the rotating blade. The material removed remains in the tip of the housing and can be used for morphologic examination as well as for functional studies with individual cell cultures. Experience published to date encompasses the results of 1032 treated stenoses. The majority of the treated lesions, 53%, were localized in the left anterior descending coronary artery; in 22% the lesion were located in the right coronary artery, in 17% in an aorto-coronary venous bypass graft. Due to the difficulty in positioning the relatively rigid atherectomy catheter, the method has only been employed in the circumflex artery in 6%. In a substantial number of patients, the stenoses had already been subjected to PTCA; in 57% of 963 patients treated with atherectomy, angioplasty had been performed previously, in 25% bypass grafting had been carried out. The primary success rate was 93%.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulse oximetry has been recently introduced into anesthetic practice as an additional monitoring technique. In contrast to other methods (ECG, inspection, auscultation, blood gas analysis), it immediately detects an impending lack of oxygen, whatever its cause. Therefore, especially in pediatric risk patients, precious time can be saved. This is illustrated during the perioperative period for correction of gastroschisis. Even with a critical look at the mishaps of this method - overestimation of true O2 saturation (sO2) and partial O2 saturation (psO2) and overestimation of hemoglobin derivatives--pulse oximetry seems superior to the established monitoring techniques in the perioperative period. Therefore, we believe pulse oximetry to be an useful tool for additional monitoring, especially in pediatric risk patients. It is a suitable continuous and noninvasive in vivo technique for the early detection of hypooxygenation. Due to the special disadvantages of the method, we consider it advisable to perform control measurements with a CO-oximeter from time to time.