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Biomedical subjects

C Velican

Publications and source records attributed to C Velican.

At least 109 records · Page 6Linked to original sources
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Coronary anatomy and microarchitecture as related to coronary atherosclerotic involvement.

A report is given on the authors' main results concerning the anatomy and microarchitecture of human coronary arteries as related to atherosclerotic involvement and to the clinical manifestations of coronary heart disease. The peculiarities of anatomical branching pattern, of the intimal thickening, muscle columns development, of age-related changes, in the intima/media thickness ratio, as well as the segmental characteristics in susceptibility to plaque development and in the plaque pattern are presented. Our results allow to delineate the coronary arterial bed as an entity in anatomical, histological and pathological sense.

Aging↗
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Silent myocardial ischemia.

Encouraging gains have been made during the last decade toward the identification of silent myocardial ischemia as a clinical form of coronary heart disease and also as its earliest and most common manifestation. Many efforts have also been made in elucidating the incidence, pathogenesis, pathophysiology, as well as the specificity of laboratory tests and the relation to risk factors and to symptomatic ischemic episodes. Once thought to be an unusual phenomenon, largely confined to anecdotal reports, silent myocardial ischemia is now recognized to be a common occurrence in the middle-aged and elderly people. The first part of this selective review summarizes major findings and conclusions concerning: (a) the identification of silent myocardial ischemia as the earliest form of coronary heart disease; (b) the selection of patients; (c) the particular feature of silent myocardial ischemia pathogenesis.

Angina Pectoris↗
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Silent myocardial ischemia. II. Pathophysiology, relation to risk factors, treatment.

The second part of this selective review on silent myocardial ischemia summarizes major hypotheses, viewpoints, findings and conclusions concerning: (a) the pathophysiology of silent myocardial ischemia; (b) the influence exerted by some risk factors for coronary heart disease in the precipitation of silent myocardial ischemia, particularly smoking and psychosocial stresses; (c) the medical treatment of silent myocardial ischemia, which, in a monitored environment, can produce definite improvements in laboratory tests, evolution of coronary heart disease and survival rates.

Coronary Disease↗
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Role of thrombosis in the onset, progression and obstructive character of coronary atherosclerotic plaques.

A study was carried out on the role of successive microthrombi incorporation and intramural thrombi formation in the onset, progression and obstructive character of coronary atherosclerotic plaques. The coronary arterial tree of 836 apparently healthy subjects 1 to 50 years old who died of accidental causes was investigated. The onset of coronary atherosclerotic plaques having as precursors thrombi could be detected in 10% of advanced lesions. The left anterior descending artery appeared as the vessel of the coronary arterial tree the most susceptible to plaque development induced by thrombi and to the occurrence of thrombi on preexisting plaques. This occurrence of thrombi on preexisting plaques was recorded in 48% of subjects aged 46 to 50 years and was followed by a severe luminal narrowing in the major coronary arteries.

Adolescent↗
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Coronary atherosclerosis: where are we now?

An attempt is made to present and summarize recent results in atherosclerosis research which may aid to a better understanding of atherogenesis, progression of atherosclerotic lesions and occurrence of myocardial ischemia. Based on selected data from the available literature and the authors' experience, the review focuses the attention on: the atherogenic role of hemodynamic stresses; the onset and fate of early coronary atherosclerotic lesions; the development of lesions of possible clinical significance; the concept of "critical stenosis"; the view that atherosclerosis is a hyperplastic and/or neoplastic disease.

Coronary Artery Disease↗
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The improper use of the term "normal" in atherosclerosis research.

The improper use of the term "normal" was frequently detected in the available literature, in studies dealing with coronary artery anatomy, pathology and angiography, as well as in epidemiological investigations. Many examples are presented which try to demonstrate that without a clear understanding of the normal, it is a very difficult task to explore the abnormal during coronary atherogenesis and the successive stages which form the natural history of coronary atherosclerosis.

Animals↗
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A further study on the influence exerted by vascular geometry on coronary atherosclerotic involvement.

A further study was carried out on the relationship between coronary artery geometry and atherosclerotic involvement. The results show that: a) the coronary artery geometry may expose an individual at an early age to an increased risk for developing atherosclerotic lesions; b) the presence, in the coronary arterial bed of vessels with large diameters (greater than 2 mm) and the succession of numerous branching points also appeared as atherogenic conditions; c) the type of atherosclerotic lesion (proliferative, insudative, necrotic, lipid-rich) was, in our material strongly influenced by the geometry of branch sites.

Adolescent↗
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The relationship between intimal necrosis and lipid accumulation during the onset and progression of atherosclerotic lesions.

In human coronary arteries, aorta and intracranial arteries, the first areas of intimal necrosis preceded the onset of the first lipid accumulation related to atherosclerotic involvement. Both intra- and extracellular lipid accumulations developed only in preexisting areas of intimal necrosis. Intimal necrosis not only caused an abnormal intraarterial retention of fat, but also caused fat to be deposited preferentially in specific forms and particular locations. The areas with mucoid necrosis appeared as adequate sites for the onset of fatty streaks; the areas with swelling necrosis appeared as adequate sites for a diffuse extracellular retention of tiny lipid droplets; the areas with dissecting necrosis appeared as adequate sites for large fatty deposits rich in cholesterol clefts. The results of this paper demonstrate that human atherosclerosis has many attributes of a necrotizing arteriopathy and that lipid accumulation is a secondary phenomenon. These results add support to the insudative theory of atherogenesis built up by German pathologists at the middle of this century and disagree with the often repeated view that human atherosclerosis is a reaction of the arterial wall to lipid that invade it.

Adolescent↗
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Centrifugal extension of coronary intimal necrotic areas.

The use of serial cross-sections, camera lucida drawings and photographic reconstruction of longitudinally cut samples, revealed that about half of intimal necrotic areas present in the coronary arteries of subjects aged 41-50 years exhibited a longitudinal diameter greater than 1.0 cm, occurring as very long lesions. In the 16 intimal necrotic areas included in a tridimensional study the longitudinal diameter was 7.8 times greater than the transverse one and 11.3 times greater than the luminal-medial diameter. The important centrifugal extension of coronary intimal necrotic areas during the fifth decade of life, particularly in male subjects, could not be detected grossly; it required a meticulous light microscopic examination of stained tissue section. This centrifugal extension was sometimes associated with the presence of a "border zone" of intermediate injury developed at the point where the intimal necrotic area irradiated in the direction of blood flow. This distal side of the lesion appeared as a highly irregular boundary with numerous peninsulas of interdigitating necrotic and apparently normal connective tissue. The present results, associated with those of our previous reports, support the view that human atherosclerosis has many attributes of a necrotizing arteriopathy.

Accidents, Traffic↗
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Prevalence of the "normal" aspect of the coronary arteries in an unselected population sample of Bucharest aged 1-60 years.

The coronary arterial trees obtained from 640 subjects 1-60 years old were studied grossly and by light microscopy, including morphometric methods. The highest values of of the ratio intima/media thickness were recorded in successive age groups, with special reference to those topographic sites where this ratio acquired an abnormal value. The percent of children, adolescents, young and mature adults free of atherosclerotic plaques, gelatinous lesions and intima necrotic areas, fatty streaks and intramural thrombi was also evaluated. An association was revealed between the number of subjects with anatomically normal coronary arteries and the presence of the common type of distribution of the coronary arteries in these subjects.

Aging↗
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Presence of atherosclerotic lesions connected with the coronary artery lumen.

Starting from five accidental observations made on isolated tissue sections on the existence of "anchored" lesions in the coronary arteries of adolescents and young adults, 47 selected coronary artery samples removed from subjects 16-40 years old were submitted to a three-dimensional investigation. Based on serial sections and sequential camera lucida drawings, the geometry, diameters and spatial connections of 42 intimal necrotic areas were recorded. All these lesions appeared in a three-dimensional plane connected with the coronary artery lumen by one or several necrotic bands which seemed to communicate freely with the luminal cavity. The role of "anchored" lesions of young subjects as precursors of lipid-rich centers of fibronecrotic plaques of mature adults and elderly people is stressed.

Adolescent↗
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Atherogenic anatomical patterns of coronary arteries branching related to cardiac and non-cardiac causes of death.

A gross and light microscopic study carried out on 102 selected male subjects aged 51-70 who died of ischemic heart disease and on 102 selected, male subjects of similar age, who died of noncardiac causes revealed that: in subjects who died of ischemic heart disease the prevalence of atherogenic deviations from the common type of distribution of the coronary arteries was 2-4 times greater than in subjects who died of non-cardiac causes; subjects who died of ischemic heart disease, with the atherogenic deviations from the common tape of distribution of the coronary arteries showed an increased number of stenotic atherosclerotic plaques and a particular propensity to "clustering" of these lesions, predominantly around branch mouths.

Aged↗
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Method-dependent number and topography of coronary narrowings.

A comparative gross and light microscopic study of the coronary arterial bed carried out on 95 selected male subjects aged 51-55 years, revealed that the number and topography of narrowings (more than 50% luminal insufficiency) showed wide method-dependent variations. If only routine gross inspection of the major coronary arteries was performed (method 1) 52% of the subjects exhibited narrowings; if gross inspection was extended to the proximal segment of the first diagonal, first septal, left marginal, right marginal and posterior descending vessels, the proportion of subjects with coronary narrowings augmented to 61% (method 2); finally the use of the light microscopy to investigate vessels supplying the conduction system and terminal vessels (method 3) augmented this proportion to 73%. Conversely, we recorded the absence of narrowings encroaching more than 50% in 48% of the subjects with method 1, in 39% with method 2 and in only 27% with method 3. Using the second method we revealed in coronary branches 29 narrowings and with the third method 52 narrowings. From the 95 cases investigated 46 (48%) did not show narrowings in the major coronary arteries. Of these 46 cases, 17 (37%) exhibited narrowings in coronary branches. This would indicate that more than 1/3 of the subjects without greater than 50% narrowings in the major coronary arteries showed such lesions in the branches of these major coronary arteries. The results of this study demonstrated the necessity of gross and light microscopic examination of the whole coronary arterial bed in all attempts to offer a realistic anatomo-clinical correlation in ischemic heart disease: they also demonstrated that the atherosclerotic involvement of the coronary arterial bed is not limited to the segments grossly examined by each pathologist.

Accidents↗
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A method which improves anatomo-clinical correlations in ischemic heart disease.

A study carried out on 595 unselected subjects aged 21-55 years who had died of accidental causes and on 56 selected patients who had died of myocardial infarction showed that the light microscopic examination of coronary branch vessels led to an obvious improvement of anatomo-clinical correlations in ischemic heart disease. These branch vessels included atherosclerotic plaques in 51% of unselected subjects 51-55 years old, dead of accidents and in 73% of selected patients dead of myocardial infarction. Severe stenotic plaques of possible clinical significance were found in 14% of subjects dead of accidents and in 48% of patients dead of myocardial infarction. In these cases the atherosclerotic involvement in the major coronary arteries (left anterior descending, circumflex and right coronary arteries) did not reach the level of possible clinical significance (greater than or equal to 75% reduction of the vessel diameter). Several examples emphasize the importance of stenotic lesions in the first diagonal, first septal, posterior descending, left marginal and right marginal vessels, as well as in the vessels supplying the sinoatrial and atrioventricular nodes for an adequate anatomo-clinical correlation in ischemic heart disease.

Accidents, Traffic↗
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Intimal thickening and atherosclerotic involvement of the left main coronary artery.

A post mortem study carried out on 886 apparently healthy children, adolescents, young and mature adults of an unselected population sample of Bucharest who died of accidental causes, revealed that the left main coronary artery acted as an atherosclerosis-resistant segment of the coronary arterial bed. The importance of this natural resistance was demonstrated by means of a comparative investigation involving the degree of intimal thickness, the intima thickness versus media thickness ratio, the per cent of subjects with atherosclerotic plaques and the obstructive character of these plaques. These parameters were examined in 6 selected topographic sites: (a) at 5 mm distal to the origin of the left main coronary artery, compared with those detected at 10 mm and 20 mm distal to the point of origin of the anterior descending artery; (b) at 5 mm from the aortic origin of the right coronary artery, compared with those recorded at 20 mm and 30 mm from the same point of origin.

Adolescent↗