Heart disease includes various conditions that affect the heart’s structure and function. Understanding these conditions involves recognizing the physical changes within the heart’s chambers, valves, and blood vessels. This article explains how common heart conditions alter the heart’s internal structure and how it operates.
The Healthy Heart: A Foundation
A healthy human heart functions as a muscular pump, circulating blood throughout the body. It consists of four chambers: the right and left atria (receiving blood) and the right and left ventricles (pumping blood out). Four one-way valves—the tricuspid, pulmonary, mitral, and aortic valves—regulate blood flow between chambers and into the major vessels.
Blood enters the right atrium from the body through the vena cava, then flows into the right ventricle before being pumped to the lungs via the pulmonary artery. Oxygenated blood returns from the lungs to the left atrium through the pulmonary veins, moves into the left ventricle, and is then ejected into the aorta for distribution to the rest of the body. The heart muscle receives its own blood supply through the coronary arteries, which branch off the aorta to deliver oxygen and nutrients.
Common Heart Conditions and Their Impact
Coronary Artery Disease and Atherosclerosis
Coronary artery disease (CAD) often results from atherosclerosis, where fatty deposits (plaque) build up within the coronary arteries. This buildup narrows and hardens the arteries, restricting oxygen-rich blood flow to the heart muscle. Over time, these plaques can rupture, leading to blood clot formation that further blocks the artery, potentially causing a heart attack (myocardial infarction), where heart muscle is damaged from lack of blood.
Heart Failure
Heart failure develops when the heart muscle becomes weakened or stiff, impairing its pumping ability. Heart chambers, especially the ventricles, may enlarge and stretch (dilate), becoming less effective at pushing blood forward. Alternatively, heart muscle walls can thicken and become rigid (hypertrophic cardiomyopathy), reducing the chambers’ capacity to fill. Both scenarios reduce pumping efficiency, causing blood to back up in the body.
Valvular Heart Disease
Valvular heart disease involves malfunctions of the heart’s valves, which can narrow (stenosis) or leak (regurgitation). In stenosis, a valve’s opening becomes stiff and constricted, forcing the heart to work harder, potentially leading to chamber enlargement or thickening. Regurgitation occurs when a valve does not close completely, allowing blood to flow backward into the preceding chamber, causing increased volume load and enlargement of the affected chamber.
Congenital Heart Defects
Congenital heart defects are structural abnormalities of the heart present at birth, with varying complexity. A common example includes septal defects, often called “holes in the heart,” which are openings in the septum separating the heart’s chambers. An atrial septal defect is a hole between the upper chambers, while a ventricular septal defect is a hole between the lower chambers. These allow oxygenated and deoxygenated blood to mix, altering normal blood flow.
Detecting Heart Disease: Visualizing the Damage
Medical professionals use various diagnostic tools to visualize the heart’s structure and function, creating “diagrams” of heart disease. An echocardiogram uses sound waves to produce moving images of the heart, revealing the size and shape of chambers, the movement of valves, and the flow of blood through the heart. It detects enlarged chambers, thickened walls, or abnormal valve motion and leakage.
Angiography, often performed during cardiac catheterization, involves injecting a special dye into the coronary arteries while X-ray images are taken. This technique clearly outlines the blood vessels, allowing doctors to visualize blockages or narrowings caused by plaque buildup within the coronary arteries. It provides a detailed roadmap of the heart’s blood supply system.
Cardiac Magnetic Resonance Imaging (MRI) uses strong magnetic fields and radio waves to create highly detailed, three-dimensional images of the heart. This advanced imaging can assess the heart’s structure, pumping function, and detect areas of damaged or scarred heart muscle tissue, providing comprehensive insights into overall heart health.
Similarly, a Cardiac CT scan utilizes X-rays to generate cross-sectional images of the heart and its vessels. It is particularly effective for visualizing calcium deposits in the coronary arteries, which can indicate atherosclerosis, and for assessing the overall structure of the heart and great vessels.