When it comes to the human body, it’s tough to argue with the critical importance of the heart. As the pump that delivers blood (containing oxygen and other nutrients) to the rest of the body, the heart is a workhorse, and associated disease can obviously spell trouble. In fact, heart disease is the leading cause of death worldwide. So if you’re going to baby just one organ, this would definitely be a solid choice. But what causes heart disease? Here is a primer.
The Basics
As above, the heart is a perfectly coordinated muscular pump that keeps blood circulating throughout the body. The human heart consists of four chambers, two on the right side (right atrium and ventricle) and two on the left side (left atrium and ventricle). A series of valves controls the flow of blood into and out of these chambers.
Blood returning to the heart from the rest of the body is low in oxygen (as the oxygen has been utilized). This blood enters the right atrium, and after passing through the tricuspid valve, the right ventricle. The right ventricle pumps the blood through the pulmonary valve to the lungs where the blood’s oxygen content is replenished. The oxygen-rich blood enters the left atrium, and after passing through the mitral valve, the left ventricle. The left ventricle pumps the oxygen-rich blood across the aortic valve to the rest of the body, with the blood ultimately returning to the right atrium (and so on).
In reality, the two sides of the heart work simultaneously.
Types of Heart Disease
What follows is a ridiculously concise summary of what causes heart disease, so concise that it is not remotely comprehensive. And the compartmentalization is artificial, as various types of heart disease often occur in concert. If you happen to be a cardiologist or a cardiac surgeon, maybe you should read our post about progressive rock instead.
Coronary Artery Disease
The heart muscle (myocardium) requires its own blood supply in order to work correctly. In other words, the heart pumps blood through a set of arteries (called coronary arteries) that actually feeds the heart muscle itself. If the coronary arteries are narrowed or blocked, typically by fatty plaques in a process called atherosclerosis, the myocardium can be threatened. If severe enough, part of the muscle can actually die, better known as a heart attack. Treatment of coronary artery disease can involve medication, an angiogram to directly open blockages, or bypass surgery to bypass blockages.
Myocardial Disease
The myocardium can become diseased directly (independent of blood supply) via a variety of mechanisms. The umbrella term for such pathology is cardiomyopathy. An example would be abnormal dilation of the left ventricle, a process that can be caused by factors ranging from viral infections to toxins such as alcohol. In other cases, the myocardium can become hypertrophic (too thick), caused by certain genetic mutations or high blood pressure. Finally, the muscle can become excessively rigid due to several less common conditions. Medications can play an important role in cardiomyopathy therapy, with more invasive procedures being an option in some cases.
Valvular Disease
The valves mentioned above can experience narrowing (stenosis) or leakiness (regurgitation) that can affect the proper flow of blood through the heart chambers. If stenosis or regurgitation is severe enough, valve repair or replacement could be needed.
Arrhythmia
The coordinated muscular contraction of the heart is governed by a precise electrical system. If this electrical system malfunctions, the heart can beat too slowly or too rapidly. Such abnormalities in heart rhythm are termed arrhythmias. In the case of a slow heart rhythm, a pacemaker could be required. Abnormally fast heart rhythms can be managed with medication and/or procedures that directly modify the electrical system. At times, depending on the specific rhythm abnormality, a defibrillator can be placed to lower the risk of sudden cardiac death.
Diagnosis
Heart disease can present with a variety of symptoms including chest pain, shortness of breath, nausea, sweating, fatigue, fluid retention, palpitations, lightheadedness, and fainting. At times, symptoms could be minimal.
If heart disease is suspected, a variety of studies can be ordered to pinpoint the exact cause. Examples include an electrocardiogram (EKG), basic blood tests, and an echocardiogram (ultrasound of the heart). Other options include a stress test, a CT scan, an angiogram, cardiac MRI, and various types of monitors to track heart rhythm.
Prevention
While the genetic factors and age-related processes that contribute to heart disease cannot be readily modified, other risk factors can definitely be controlled. Diabetes, high blood pressure, high cholesterol, lack of exercise, excess weight, and smoking are key contributors to coronary artery disease. Addressing these issues in a timely fashion can avoid undesired outcomes.
Modification of the aforementioned risk factors can also be important for heart health in other ways. As an example, proper control of blood pressure can avoid hypertrophy of the myocardium. Similarly, valvular disease may be more likely to occur in the context of unfavorable lifestyle practices. Finally, arrhythmias tend to be more common in the context of high blood pressure and diabetes.
To start off on the right foot, go ahead and skip the chicken wings and ribs tonight. In fact, you may also want to lay off the mac and cheese. It’s time to live it up. It’s time for some boiled asparagus and water.
