How does stress cause heart disease?
Stress and heart disease has various aspects. Stress can lead to increase in risk factors for heart disease as well as precipitate symptoms in a hitherto silent heart disease. Most older persons have build up of plaques in the blood vessels of the heart (coronary arteries). When there is a sudden severe stress, heart rate and blood pressure can shoot up. This can lead to increase of shear stress on the fat plaques in the blood vessels of the heart. A small break may form in the covering of the plaque, exposing the inner cells. Blood components known as platelets adhere to these breaks in the inner surface of the blood vessels and initiate the formation of blood clots. Blood clots in turn block the flow of blood in the vessel, leading to damage of heart muscle known as heart attack.
Sudden stress can sometimes lead to a surge in the blood levels of certain hormones like adrenaline. These contribute to the surges in blood pressure and heart rate. In addition this can upset the heart rhythm leading to life threatening rhythm disorders (cardiac arrhythmia) which can sometimes cause sudden stoppage of the heart (cardiac arrest).
Another manifestation of stress in the heart is the ‘broken heart syndrome’ or stress cardiomyopathy. This was initially described more in elderly females after sudden demise of their spouse. Part of the left ventricle (lower muscular chamber of the heart) becomes enlarged, giving it the name apical ballooning. This occurs in the absence of any blockage to the blood supply. Most of these cases do recover sooner or later. Stress cardiomyopathy has been described along with multiple other forms of stress other than bereavement.
Stress in general changes our life style and we may eat more of carbohydrate and fat. This has long term consequences like increase in body weight, blood sugar and blood pressure. These can further increase the chance of heart disease. Stress increases the blood pressure and blood sugar through hormonal influences even without a change in the diet pattern.
What are the different types of heart disease?
Important types of heart diseases are congenital heart disease, rheumatic heart disease, hypertensive heart disease, ischemic heart disease and inflammatory heart disease. Congenital heart diseases are birth defects of the heart. Though they are present at birth, they need not manifest at birth. Many of them manifest only in adult life. Rheumatic heart disease is a sequelae of rheumatic fever and affects predominantly the valves of the heart, leading to valvular heart disease. Hypertensive heart disease occurs due to high blood pressure. Ischemic heart disease is due to decreased blood supply to the heart, usually as a result of partial or complete blocks in the coronary arteries which supply oxygenated blood to the heart muscle. Inflammatory heart disease could be secondary to infection or due to abnormal immune mechanisms. It can involve any of the three layers of the heart. Disease of the outer layer is known as pericarditis. Muscular part of the heart is involved in myocarditis. Inner layer is involved in endocarditis. Endocarditis is mostly infections of the heart valves which are derived from the inner layer (endocardium). Endocarditis most often occurs in valves which have been already damaged by some other disease like rheumatic heart disease. Another form of heart disease is cardiomyopathy in which heart muscle is primarily diseased. There are several varieties of cardiomyopathies or heart muscle disorders, some of which can also be inherited or run in families. Tumors though rare, can sometimes occur in the heart. Tumors of the heart are most often secondary, spreading from diseases elsewhere in the body, though primary ones are also seen occasionally.
Any of these forms of heart diseases, if severe, can lead to failure of the functions of the heart (heart failure). In addition to these different types of heart disease mentioned above, there are several disorders of the heart rhythm or electrical disorders of the heart (cardiac arrhythmia). Heart rhythm disorders can also lead to heart failure if the heart rate remains high for a long period. Heart rhythm disorders can be associated with other structural disorders of the heart listed above.