Influence of the chosen model of stenosis on pressure-flow relationships in isolated perfused arteries

The effect of peroxides on the vascular endothelium of isolated pig aorta in vitro

The effect of peroxide on endothelial cells (perfused pig aorta) was examined using an in vitro perfusion model. Hydrogen peroxide was added to the perfusion medium (pig serum together with a buffer solution) which was expected to lead to an increased oxidation of lipids and lipoproteins. Oxidation processes of this type play a decisive role in the pathogenesis and progression of arteriosclerosis. The aim of the present investigation was to demonstrate by introducing hydrogen peroxide (H2O2) in varying concentrations (0.5-1.5%), the destructive impact of peroxides on the endothelium, while these cells are believed to play a key role in the pathogenesis of arteriosclerosis. The extent of endothelial cell impairment was assessed by means of silver staining visualisation of endothelial cell borders as well as light- and scanning-electronmicroscopic investigation. It was discovered that the endothelial cells show increasing impairment after 10 h of perfusion due to the effect of peroxide (hydrogen peroxide).

Description of a simple method to study some aspects of the pathogenesis of arteriosclerosis by perfusion of arterial segments

A perfusion apparatus is described which permits the perfusion of arterial segments of about 5 cm in length. It works under physiological conditions. During the perfusion, temperature and pressure constancy or pressure variation, respectively, pulsation, sufficient oxygen supply, and high sterility are guaranteed. Hitherto, the duration of the perfusion has been extended to 10 h. After this time the endothelium was well preserved. The method shall be used for the study of some problems in arteriosclerosis research.

Louis F. Bishop lecture. Role of coronary artery spasm in symptomatic and silent myocardial ischemia

The revival of the concept of coronary spasm has stimulated research into coronary artery disease. Observations in patients with variant angina have substantially contributed to the appreciation of painless myocardial ischemia. However, the presence or absence of pain during ischemic episodes is not related to the cause of ischemia, because painless ischemia can be observed in variant angina (caused by spasm), in effort-induced angina (caused by increased myocardial demand) and in myocardial infarction (caused by thrombosis). Continuous monitoring initially of patients with variant angina and subsequently of patients with unstable and stable angina proved that often painful and painless ischemic episodes are caused by a transient impairment of regional coronary blood flow rather than by an excessive increase of myocardial demand. The transient impairment of coronary flow appears to be caused by dynamic stenosis of epicardial coronary arteries. This most often occurs at the site of atherosclerotic plaques encroaching on the lumen to a variable extent. Dynamic stenosis can be caused by 1) "physiologic" increase of coronary tone, as in stable angina, 2) spasm, as in variant angina, and 3) thrombosis, usually in combination with "physiologic" changes in tone or with spasm, or both, as in unstable angina. The mechanisms of spasm, as typically observed in variant angina, are different from those of "physiologic" increase of tone; they appear to be related to a local alteration that makes a segment of coronary artery hyperreactive to a variety of constrictor stimuli causing only minor degrees of constriction in other coronary arteries. The nature of this abnormality, which may remain stable for months and years, is yet unknown.