The heart and the roots of the great vessels entering and leaving the heart are contained within the tough coated sac of the fibrous pericardium, which is itself a source of clinical problems.
In essence the heart is a muscular sac, with four chambers, lined with endothelium, separated by valves, and like all structures, supplied with nerves and blood vessels. Each of these components has its own specific conditions, collectively they may share problems of disease or degeneration.
Muscle disease (cardiomyopathy)
The commonest cause of damage to the heart muscle is non-specific, due to interference with blood supply (ischemic heart disease).
There are numerous specific causes, the symptoms are often vague, the diagnosis difficult and the end result poor, not infrequently life is saved by a cardiac transplant. Among these causes are genetic, metabolic (amyloidosis, hemochromatosis), inflammatory (Chagas disease), endocrine (diabetes, hyperthyroidism, acromegaly), toxic (chemotherapy, alcoholism), and nutritional deficiency (Vitamin B).
The lining of the heart muscle and valves may become inflamed due to infection or non-infection causes. There is a particular problem in regard to the valves which do not have a blood supply, hence there are no mechanisms for attacking organisms that attach to them nor can antibiotics reach those organisms.
Acute endocarditis is a life-threatening condition due to invasion of the blood stream (bacteremia). Sub-acute endocarditis (SBE) is clinically more common, and is usually associated with pre-existing heart valve damage. Once established and colonizing the edge of the valve, infectious thrombi may dislodge and cause infection elsewhere in the body.
The function of the valves in the heart is like a lock in a canal, to control the flow of blood, to permit free flow at the appropriate moment, and to prevent back flow. The clinical problems with the heart valves may be because the valve is too tight (stenosis) or too loose (insufficiency leading to regurgitation). Some of these problems are congenital, some came from the now less common rheumatic fever with subsequent heart disease, some follow bacterial infection.
A condition of the valves between left ventricle and atrium, designated mitral valve prolapse, is reported variously as very common, or moderately uncommon, and of no clinical significance or with an associated 20% mortality rate.
Correction of valvular stenosis by digital stretching was among the earliest venture in open heart surgery, where the real advance was not in surgery so much as in anesthesia.
Hypertensive Heart Disease
The form of disease of the heart associated with the “silent killer” raised blood pressure (hypertension). Called silent killer because the patient may be unaware of the problem, and never seek care.
The condition of the heart arises with the attempt to cope with the increased “after-load” the force necessary to drive blood through the altered vascular system. In the early stages there are neither symptoms nor signs; in the later stages as the heart fails to keep up with the increased effort there is pain due to insufficiency of coronary artery perfusion, the neck veins enlarge due to back pressure, and the left ventricle is seen on X-ray to be enlarged giving the heart a “boot-shaped” appearance.
Congestive Heart Failure
This is the end result of several possible conditions; the heart can no longer serve its functions of sending blood to the lungs to get oxygenated, and sending the oxygenated blood to the body. The veins swell, fluid accumulates in the body cavities (ascites), and the tissue fluid is not cleared. The body becomes grossly swollen (anasarca) particularly in dependant areas, the legs edematous if seated, over the sacrum if confined to bed.
Coronary artery disease (CAD)
From the practical standpoint, Coronary Artery Disease is synonymous with Coronary Artery Atherosclerosis, but from the pathologist’s point of view, important other conditions are overlooked in that context.
Risk factors for Heart Disease
Correctible risk factors:
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