[Atherosclerosis and ischemic heart disease. Short historical notes]

A review of some historical accounts in Medicine reveals concepts, clinical descriptions and prognosis of coronary atherosclerosis and ischemic heart disease in the recent past and in remote antiquity. Herein, the historical accounts disclosed include some concepts and terms utilized in reference to atherosclerosis: the oldest documentation of coronary atherosclerosis and myocardial infarction in Egyptian mummies; the clinical syndrome of angor pectoris in the Ebers' papyrus, as well as clinical and prognostic data in the Corpus Hippocraticum regarding possible cases of angina, infarction and sudden death. These reports give a better insight into primitive medicine in the Ancient Western World, revealing the evolving concept of atherosclerosis and the existence of this disease in humanity's remote past.

Dietary protein, cholesterol and atherosclerosis: a review of the early history

The first purely nutritional investigation into experimental atherosclerosis was carried out by Ignatowski in 1908. Believing that a toxic metabolite of animal protein led to atherosclerosis, he fed meat to adult rabbits and milk and egg yolk to weanling rabbits and caused atherosclerosis. For the next two decades experimental efforts from many laboratories were directed at determining which, if any, animal protein was the most atherogenic. The discovery in 1912 that dietary cholesterol per se was atherogenic turned attention to fat and cholesterol, eclipsing work on dietary protein. In 1926 Clarkson and Newburgh showed that the amount of cholesterol present in the animal protein they fed was insufficient to be atherogenic, demonstrating that some factor other than lipid determined atherogenicity. In 1940 Meeker and Kesten showed that animal protein (casein) was more atherogenic that plant protein (soy). Carroll and his co-workers showed that most proteins of animal origin were more cholesterolemic for rabbits than were proteins of vegetable origin, although there was some overlap. Cholesterol turnover is slower and fecal excretion of cholesterol is reduced in rabbits fed casein as opposed to those fed soy protein. The mechanisms underlying this effect are moot.

Arteriosclerosis: its morphology in the past and today

In a brief historical review the contributions of Rokitansky, Virchow, and Langhans concerning the pathogenesis of arteriosclerosis and the histogenetic puzzle of intimal cells classification are described. Then, some unresolved problems are discussed, especially the localization and distribution of arteriosclerotic plaques, the shape of endothelial cells and the orientation of their nuclei in correlation to local hemodynamic stress under normal and pathologic conditions. Some differences between experimental arteriosclerosis and arteriosclerosis in humans are illustrated by examples. The key role of the endothelium in the development of arteriosclerosis is well founded. According to recent investigations some cells on the surface of human arteriosclerotic plaques appear to be of non-endothelial origin. Arteriosclerosis seems to be a systemic disorder with multiorgan involvement. Individual cases, however, show significant differences in the distribution and extent of lesions. Today, arteriosclerotic research is focused on arteries being most important in clinical investigations. Nevertheless, there are also other arteries with severe arteriosclerotic lesions; for example, the degree of arteriosclerosis in periprostatic arteries is more pronounced than in coronary artery branches of the same size. Finally, the importance of primary prevention of arteriosclerosis is emphasized.

[Two thousand years of historical study on the words atheroma, atheromatosis, atherosclerosis, arteriosclerosis]

Renowned authors, when studying arterial diseases, use indifferently the words atheroma, atheromatosis, atherosclerosis or arteriosclerosis. The historical record of these words permits the justification of a selective choice. The word atheroma was created by Celsius, two thousand years ago; he have it the meaning of fatty tumor, which was kept till the middle of the nineteenth century. The word atheromatosis appeared on 1815, since J. Hodgson defined so the fatty arterial degeneration. Marchand, from Leipzig, proposed on 1904 the word atherosclerosis which has always been with us. The term arteriosclerosis was well defined on 1833 by Lobstein, from Strasbourg. The authors propose to reserve the word atherosclerosis to the arterial disease described by the WHO, to keep the words atheroma and atheromatosis to anatomical lesions well-defined. Arteriosclerosis is a disease which invades an extensive arterial network, with a particular anatomical image.

[Historical development of the cholesterol-atherosclerosis concept]

The development of the cholesterol hypothesis to the cholesterol theory, as related to atherogenesis, is followed in chronological sequence. The major milestones in terms of chemical pathology of the lesions, clinical observations on serum cholesterol levels in patients with coronary heart disease, lipoprotein research, epidemiological investigations and prevention of diseases due to atherosclerosis are described within three time periods: from the 19th till the beginning of the 20th century, the years between the two World Wars and the last 40 years. A total picture emerges which assigns to cholesterol and its lipoprotein carriers a key role in the origins and progression of atherosclerosis. These causal relationships have opened the way to the prevention of the disease, supported by intervention studies aimed at reduction of serum cholesterol levels.

Lipoprotein analysis. Early methods in the diagnosis of atherosclerosis

Before 1950, there was no clear perception of the interrelationship of serum lipids, atherosclerosis, and coronary heart disease. Since then, research laboratories have made conflicting claims for the most useful measurement of the serum lipid levels in detecting and managing coronary heart disease. Emphasis has been placed in turn on the measurement of levels of serum cholesterol, lipoproteins, triglycerides, and, currently, cholesterol and lipoproteins again. Physical separation and characterization of serum lipoproteins by ultracentrifugation and electrophoresis resulted in two classification systems for lipoproteins based on hydrated density and electrophoretic mobility, respectively. Two operational by-products were the atherogenic index, an empirical formula supposed to correlate with coronary heart disease, and a phenotype system for classification of the lipoproteinemias. Current National Heart, Lung, and Blood Institute criteria for atherosclerosis risk implicate elevated levels of cholesterol and low-density lipoprotein cholesterol, and decreased levels of high-density lipoprotein cholesterol. Although triglycerides are closely associated with cholesterol in lipoprotein molecules and are positively associated with cardiovascular disease, there is no strong evidence of elevated levels of plasma triglycerides as an independent risk factor in coronary heart disease. Elevated levels of triglycerides can help identify persons with increased risk of cardiovascular disease from other causes, but screening for hypertriglyceridemia is not recommended. Apolipoproteins and lipoprotein Lp(a) are briefly discussed.

Role of the altered transmural permeability in the pathomechanism of arteriosclerosis. History of arteriosclerosis theories. Role of the altered permeability in experimental arteriosclerosis models

After presenting an overview on classification and history of arteriosclerosis theories, the physiological factors involved in the transmural permeability of the arteries are discussed in detail. The development and characteristic features of the altered transmural permeability were studied in various experimental models such as in rat's hypercholesterolemia, local aortic hypoxia, lymphedema of the vascular wall and in hypertension. Results appear to show that alterations in permeability invariably developed in all of the pathological conditions examined, they were transient in nature and preceded the onset of intimal proliferation(s). The disturbance of transmural permeability might be the common pathologic clue which initiates uniform vascular responses to injuries produced by a variety of noxious stimuli. The possible role of the altered transmural permeability in the induction of smooth muscle cell proliferation is also discussed and evidence is provided that after withdrawal of stimulus for vascular injury intimal proliferation will not develop despite the manifest disorders in permeability.

[Physiosclerosis--arteriosclerosis. Progression and regression then and now]

The clinical recognition of the physiosclerosis is still problematic even nowadays. This question seems not to be actual, since the disease arteriosclerosis with all its sequels is the superior epidemiological problem of mankind. Therefore, the inhibition of the progression and the regression of arteriosclerosis is of great interest. Now as ever, however, the coming forth of an atheromatous focus into the blood stream and the later change of the ulcer developed in such a way into fibrous connective tissue is the only regression of the arteriosclerosis in man up to now certainly made evident. A new course is adopted. Three approaches of intervention are represented with own results: favourable effects of multiply unsaturated fatty acid, importance of the trace element balance, particularly of selenium, the use of the classical risk factor concept at all ages.