Heart Disease Primer

Updated January 2, 2022

The heart is an integral organ in the human body. It is made of specialized cells that contract in response to its own electrical conductance system, keeping the blood flowing through the body. The blood carries oxygen and nutrients to every cell – returning waste products to the lungs and kidney for excretion and exhalation.

When the heart cannot function normally, the entire body suffers, and may even die. Heart disease has been the leading cause in both the United States and worldwide for most of the 21st century (see World Health Organization and U.S. Centers for Disease Control for mortality statistics). Many specific disorders fall under the umbrella of heart disease, including hypertension and congenital valve disorders, but the most common form is ischemic heart disease, a lack of blood to the heart tissue itself. In the U.S., 13 million people are estimated to have coronary artery disease.

Type	General Cause	Result	Common Treatment
Congenital heart disease	Problem with fetal heart development	Depends on exact defect – lack of oxygen, death, kidney dysfunction	Dependent on exact defect – corrective surgery, transplant, no treatment
Pericarditis/pericardial effusion	Infection or inflammation of the sac around the heart	Scarring and restriction of the heart	Anti-inflammatories, other drugs as needed, surgery
Cardiomyopathy	Primary defect in the heart muscle	Reduced function	Depends on the exact defect and result – transplant, surgery, drugs
Valve disorders	Infection, trauma, congenital, other heart disease	Shortness of breath, reduced heart efficiency, dizziness	Transplant, medications, preventing exacerbation
Rhythm disorders (e.g., afib)	Electrical system dysfunction, other heart disease	Depends on exact dysfunction – chest pains, palpitations, death	Depends on exact dysfunction – pacemaker, transplant, medication
Coronary artery disease	Atherosclerosis, clots	Heart attack (myocardial infarction)	Diet, lifestyle, medications, surgery
Ischemic heart disease	Atherosclerosis, scarring/trauma, clots	Stroke (cerebral infarction), ischemia in tissue/organs	Depends on affected vessels – surgery, medication, lifestyle

Hypertension and heart disease

Hypertension is a consistent increase in arterial pressure and causes secondary organ dysfunction, particularly of the heart and kidneys.

Hypertension can cause the heart muscle to work harder, resulting in cardiomegaly (enlarged heart, e.g., ventricular hypertrophy as seen above) and other cardiomyopathies. Eventually the heart can no longer compensate for the effects on efficiency and heart failure ensues.

Hypertension is generally caused by a combination environmental and genetic factors.

The risk of hypertension and subsequent heart disease can be reduced by reducing dietary sodium and cholesterol intake (atherosclerosis is sometimes associated with increased blood pressure), exercising, maintaining a healthy weight, and avoiding smoking and excessive alcohol intake. Genetic factors can be controlled with medications, such as ACE inhibitors and angiotensin receptor blockers (ARBs), which act on the renin-angiotensin system, a major physiological hormone system involved in responding to the body’s need for adjustments in blood pressure.

Role of cholesterol in heart disease

Coronary artery disease occurs when the supply of blood to the outer layer of the heart is inhibited or when those vessels are damaged. Blockage of the coronary arteries prevents oxygen and nutrients from reaching the outer portion of the heart and the resulting damage is referred to as a heart attack (known as myocardial infarction, or MI).

Having high cholesterol levels, particularly those of LDL type, can cause blood vessel damage and lead to heart disease when other factors are present. These factors include smoking, obesity, family predisposition and genetics including homocysteinuria, hypertension, and diabetes.

Cholesterol is made by the liver as well as being part of a healthy dietary intake of fats. Excess cholesterol is deposited in the blood vessels.

These cholesterol-laden plaques often develop over decades and are a common and normal occurrence in aging blood vessels. The hardening of the arteries and their obstruction, including that leading to a heart attack, is called atherosclerosis. Plaque development begins in youth and is enhanced by environmental or genetic factors as a person ages – the livers of some patients produce too much cholesterol, hypertension increases the stress put on the plaques and vessels, and obesity and diet increase fatty acids that perpetuate plaque buildup, to name a few.

The atherosclerotic plaques become a danger when they obstruct blood flow, rupture, or wear away the arterial wall. The event can go unnoticed or result in a severe complication, such as a heart attack, stroke, or hemorrhage. Plaques can also cause arterial walls to become worn and tear, leading to aneurysms. Clinical manifestations or complications of atherosclerosis are usually not seen until middle age. The clinical phase is more common in men, but begins to appear as frequently in women after menopause.

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