To understand the types of heart disease, it is necessary to know some basic heart anatomy. As the authors of “The Haywire Heart” note, the heart “is a miracle of plumbing and electrical circuitry, and both have to function properly for it to do its job well.”
The heart is a fist-sized organ made up primarily of cardiac muscle (myocardium). Veins passively carry deoxygenated blood (blood that has given up its oxygen to the organs and tissues) to the small, upper right chamber of the heart called the right atrium. The blood travels through the tricuspid valve to the larger chamber on the right side of the heart called the right ventricle, which pumps blood through the pulmonic valve into the lungs, where it becomes oxygenated.
Blood travels from the lungs into the smaller chamber on the left side of the heart called the left atrium. The blood then travels through the mitral valve into the large chamber on the left called the left ventricle, which pumps blood through the aortic valve into the arteries, where oxygen-rich blood travels to all the organs and tissues of the body. Oxygenated blood is carried to the myocardium via the coronary arteries.
Most heart disease in this country is caused by atherosclerosis. This “hardening of the arteries” is caused by lack of exercise and a diet high in animal products, sugar, salt, oil and processed food. An organ system called the endothelium lines the inside of the arteries and starts to thicken when stressed by bad genes; bad habits such as lack of exercise or smoking; or conditions such as diabetes, high blood pressure or high cholesterol. With continued stress to the endothelium, eventually plaque forms, which can cause chronic partial blockage of a coronary artery.
A heart attack (myocardial infarction or MI) occurs when plaque in the wall of a coronary artery ruptures, and a blood clot forms causing a complete blockage, resulting in death of myocardium and in 20 percent of cases death of the patient. Heart attacks are the main cause of death in this and other countries on a Western diet. Usually when people say they have “heart disease,” they are referring to atherosclerosis of the coronary arteries.
A second type of heart disease is congestive heart failure (CHF), where the heart muscle is damaged to the point where it loses some of its ability to pump. Blood backs up into the lungs causing shortness of breath, and into the tissues, causing ankle swelling. The usual cause of the myocardial damage is atherosclerosis, with chronic blockages and/or heat attacks. Another cause of CHF is hypertension (high blood pressure), which causes a chronic stress of the heart muscle.
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A third type of heart disease is damage to one or more heart valves. This can be congenital, but more often is caused by diseases such as rheumatic fever, which is a complication of strep infections. With the advent of antibiotics, the incidence of rheumatic fever has dropped dramatically. The primary cause of valvular heart disease now is atherosclerosis, which can cause calcification and narrowing of heart valves.
A fourth cause of heart disease is a problem with the electrical conduction system. This can result in non-serious palpitations or “skipped beats.” It can also result in more severe heart rhythm disturbances such as atrial fibrillation. Ventricular tachycardia is another serious and even life-threatening cardiac rhythm disturbance.
So when someone tells you that they have heart disease, they could mean any of these conditions. And of course there are less common types of heart disease such as myocarditis (infection of the myocardium) and endocarditis (infection of a heart valve).
Next week’s column will be about heart damage from too much exercise. Couch potatoes will love that column, but shouldn’t get too cocky because some exercise every day is clearly beneficial.
Dr. Feinsinger, who retired from Glenwood Medical Associates after 42 years as a family physician, now has a nonprofit Center For Prevention and Treatment of Disease Through Nutrition. He is available for free consultations about heart attack prevention and any other medical concerns. Call 970-379-5718 for an appointment. For questions about his columns, email him at firstname.lastname@example.org.