The human heart serves as a complex pump, diligently circulating blood throughout the body to deliver oxygen and nutrients. Understanding how this remarkable organ works, and what happens when it malfunctions, can seem daunting. This article aims to demystify common heart conditions by illustrating the changes that occur within the heart during various diseases.
Anatomy of a Healthy Heart
A healthy heart is a muscular organ, roughly the size of a fist, situated slightly to the left of the chest’s center. It consists of four chambers: the two upper atria and two lower ventricles, which pump blood in a coordinated rhythm. Valves between these chambers and at the exit of the ventricles ensure blood flows in a single direction, preventing backflow. The heart muscle receives its own supply of oxygen-rich blood through coronary arteries on its surface.
Visualizing Coronary Artery Disease
Coronary artery disease (CAD) develops when major blood vessels supplying the heart become damaged. This condition, known as atherosclerosis, involves the gradual buildup of plaque within artery walls. Plaque is a complex mixture of cholesterol, fatty substances, calcium, and other cellular waste. Over time, this accumulation causes arteries to narrow and stiffen, restricting blood flow to the heart muscle. Consequently, the heart muscle may not receive sufficient oxygen, especially during physical exertion.
Diagram of a Heart Attack
A heart attack, medically known as a myocardial infarction, is an acute event where blood flow to a section of the heart muscle is abruptly cut off. This often occurs when plaque in a coronary artery ruptures, forming a blood clot (thrombus) at the rupture site. The clot can completely block the artery, preventing oxygen and nutrients from reaching the heart muscle. Without timely oxygen, affected heart muscle cells begin to die, leading to permanent damage.
Understanding Heart Failure
Heart failure is a chronic condition where the heart can no longer pump blood efficiently enough to meet the body’s demands. This does not mean the heart has stopped working entirely, but rather that its pumping action has become weakened or stiffened over time. The ventricles, the heart’s main pumping chambers, may become enlarged (dilated) or thickened and stiff, reducing their ability to fill or eject blood effectively. This reduced pumping capacity can be a long-term consequence of damage from conditions like coronary artery disease or a previous heart attack, leading to symptoms such as fatigue and shortness of breath.