Introduction

Atherosclerotic cardiosclerosis  

Atherosclerotic cardiosclerosis is a condition in which scar tissue is formed inside the heart muscle. This condition is clinically characterized by a degeneration of the muscle fibers which get subsequently substituted with connective tissue. As a result, the number of heart muscle cells is reduced, and the heart valves become gradually deformed. This can lead to stenosis or insufficiency. This condition usually occurs in accompaniment with other cardiovascular diseases, such as coronary heart disease, myocarditis, atherosclerotic lesions of the coronary vessels, etc. Atherosclerotic cardiosclerosis is classified as an ischemic cardiopathy which is not accompanied by pain. This can occur as a consequence of atherosclerosis of the coronary arteries, which is why it has been also termed coronary atherosclerotic cardiosclerosis.

How does this disease develop?

The main cause of this disease is atherosclerosis. Age plays an important role in the emergence of this disease. Atherosclerotic cardiosclerosis usually appears in the fifth decade of one’s life and the possibility of its emergence increases with age. Hence, atherosclerotic cardiosclerosis can occur by itself or in conjunction with a common complication called stenocardia (angina pectoris) or hypertensive disease. These are all some of the most common heart diseases which occur in individuals above the age of 60.
 
Unlike the acute forms of ischemic cardiopathies, atherosclerotic cardiosclerosis is equally distributed in prevalence among the two sexes, while for the elderly is more predominant in females. Several factors contribute to the onset of the disease, including a sedentary life, a diet regimen which contains high levels of fat and cholesterol, especially fat metabolism disorders. This occurs more often in patients who are obese, diabetic, those suffering from myxedema or familial hypercholesterolemia, etc. Other patients at risk include those who face psychological tension at work, extreme emotional upheavals, smoking, menopause, ovariectomy, etc. Atherosclerotic cardiosclerosis can occur more rarely as a consequence of panarteritis nodosa or an embolism of the coronary arteries.

Mechanisms behind the development of atherosclerotic cardiosclerosis

As one’s age progresses, the vascular walls of the vessels undergo biochemical changes. Macromolecules such as beta-lipoproteins are cleaved to release cholesterol during their passage through the arterial wall. Cholesterol is insoluble, hence it precipitates and forms the atherosclerotic plaques. With the passage of time, a mesenchymal reaction occurs which leads to the sclerosis of the coronary arteries. As a consequence of the sclerosis of the coronary arteries, chronic hypoxia of the myocardium occurs. The muscle fibers undergo dystrophy, degenerate and are finally replaced by other non-contractile connective tissue.
 
When the atherosclerotic process affects important arteries which feed the circulatory pathways, atherosclerotic cardiosclerosis becomes complicated by rhythm or circulation perturbation. If the atherosclerotic processes affect the papillary muscles, they cause the muscles to contract and become shorter, hence the mitral valve (or on rare occasions, the tricuspid valve) cannot appropriately open and close, thereby also causing valve insufficiency.

What happens to the heart of a patient with atherosclerotic cardiosclerosis?

The heart becomes larger due to dilation (the enlargement of the heart chambers) and hypertrophic (enlargement of the muscle), especially in the left ventricle. In patients suffering from forms of the disease which are accompanied by hypertension, hypertrophy is predominant.
 
There are two forms visible upon tissue morphology analysis under a microscope:
1.    The diffuse form, which occurs as a consequence of the slow stenosis of the coronary arteries (this occurs more rarely)
2.    The focal form, when the fibrous tissue is distributed in a non-uniform manner. In some areas, one can observe fibrous strands which usually develop from thrombosis or stenosis of the coronary arteries. The damaged muscle fibers are substituted by fibrous tissue, whereas other fibers become hypertrophic.

Compensation mechanism

Compensation here refers to the ability of the heart to try to make up for any kind of insufficiency. The heart either begins to overexert a certain part, or it undergoes changes on a cellular level to try and compensate for the damage it has sustained.

In simple (simple meaning, uncomplicated, unaccompanied by other diseases) atherosclerotic cardiosclerosis, the early signs of heart failure may be absent for a very long time. This can be explained by the fact that usually, atherosclerotic cardiosclerosis occurs as a consequence of atherosclerosis of the left coronary artery. The left coronary artery feeds into the left ventricle; this chamber is made from the thickest, most powerful heart muscle tissue. The heart compensates for whatever part of it which has become damaged by rendering certain muscle fibers hypertrophic.

Rhythm disorders

Atherosclerotic cardiosclerosis is one of the most common causes of rhythm disruptions/disorders. Extrasystoles are the most common, which usually originate from the left ventricle, whereas right ventricle extrasystoles or atrial extrasystoles are rarer. Other common rhythm disruptions include atrial fibrillation and atrial flutter, which develop gradually as a consequence of the dystrophy of the right atrium. At the onset, they may have paroxysmal character, and as time progresses they become permanent. They are almost always present in observed advanced stages of this condition when the condition becomes further complicated with chronic cardiovascular insufficiency (heart failure). At other times, atrioventricular blockages of different stages may develop, which may lead to the ADAM-STOKES syndrome or blockage of the left branch.

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