Heart Disease and Risk Factors

The Pericardium

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.

Acute pericarditis

• Infectious: in children most of often due to the preventable Haemophilus Influenzae; in adults these days the possibility of AIDS should be considered with secondary infection with a number of organisms;.
• Cardiogenic: following an infarct; rupture of the great vessels within the pericardium.
• Traumatic: knife wounds and other penetrating injuries, including surgery; following catheterization of the heart with inadvertent penetration of the wall; blunt trauma such as in a motor vehicle accident resulting in tamponade.

Chronic pericarditis

• Infectious: tuberculosis must always be considered, regardless of origin of the patient
• Metabolic, Renal failure: resulting in uraemia
• Auto-immune, Connective tissue diseases: such as rheumatoid arthritis

The Heart
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).

Endocarditis
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.

Valve disease
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.

• Coronary artery spasm: this may be the cause of sudden death in athletes who use cocaine. The blood supply to the heart ceases at a time when the need for oxygen is greatest. There are also idiopathic causes of coronary artery spasm, which is the profession’s term for saying they know it happens but they don’t know why.
• Kawasaki’s syndrome: inflammation and dilatation of coronary blood vessels is found in this childhood condition, with interference with the blood supply to the heart which may also show a myocarditis.
• Vasculitis: inflammation of blood vessels, often segmental, and associated with the group known as connective tissue diseases.
• Coronary Artery Atherosclerosis: not realized by the general public, this condition begins in childhood; realized, but to too great an extent ignored by the general public, it is the commonest cause of death for men and women in the US.
  

Risk factors for Heart Disease

• Traditionally divided into the factors you can’t control (inherent) and those you could:
• Inherent risk factors:
• Age: not much you can do about that, but the longer you live the more likely you are to die of heart disease.
• Sex: men are more at risk than women; women are more at risk after the menopause.
• Ethnicity:
• Family history: a history of predecessors having heart disease raises the likelihood of any individual also having heart problems; there are two potential factors, genetic chromosomal causes, and learned behaviour, the likelihood that a child will live in the same pattern as his parents.  

Correctible risk factors:

• Smoking: Nicotine constricts blood vessels, carbon monoxide damages their endothelial lining.
• Diet: unreasonable intake of fats, cholesterol and salt.
• Hypertension
• Blood lipids
• Diabetes: in particular when associated with hypertension, obesity, hyperlipidemia – the  metabolic syndrome
• Obesity
• Physical inactivity
• Stress

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