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To “lie at the heart of something” is to be at the central or most crucial part of something. If you think of the heart of the United States, it may be reasonable to think of Washington, D.C. Our nation’s capital is the seat of our federal government, where major decisions are made about our democracy and our lives.

It is a place people from all over the country rely on for action, come to protest in, and send their elected officials in an effort to have their voices heard. It is a place that is structured to house the official workplaces of the three branches of our government — the legislative branch (U.S. Capitol), the executive branch (the White House) and the judicial branch (the U.S. Supreme Court). It is also a place of employment for a workforce of more than 700,000 people, a large percentage of whom reside outside of the D.C. borders and within the Washington metropolitan area.

To put it simply, the successful function of Washington, D.C., relies on the galvanization of ideas into action, the maintenance of governmental structure, and the constant influx and efflux of American citizens.

In a similar sense, the successful function of the heart (as in the literal organ) relies on electrical activity to turn signals into action, the maintenance of its muscles and valves, and the circuitous movement of blood in and out of its vessels. We may summarize these three categories into electrical, structural and circulatory systems.

When there are problems with any one of these functioning areas, the results can be either mildly irritating or utterly catastrophic. In the Washington, D.C., example, if there is a failure to pass funding or legislation, there may be government shutdowns. If governmental buildings experience insurrections, elected officials’ lives may be at risk. And if there is traffic (“congestion,” if you will) there may be a general hold on productivity from the daily workforce.

Just as much as D.C. relies on power-driven movements, structural soundness and rhythmic interchanges, so too does the heart. If any aspect of the heart’s electrical, structural or vascular systems becomes disorderly, unorganized or impaired, the entire heart can fail, with the body soon to follow.

In recognition of , a global campaign established in 1999 by the and the , this article seeks to cover the concepts of cardiovascular disease that has made it persist as the leading cause of death worldwide. (Note: Though heart disease has been recognized as the leading cause of death worldwide for the past 80 years, in the United States between December 2020 and February 2021. As of March 2021, heart disease once again topped the charts as the leading killer in the United States.)

In addition to providing information on the different types of cardiac disorders, this article provides suggestions for actions to prevent and control cardiovascular disease and shares new insights from research published in Â鶹´«Ã½É«ÇéƬ and Â鶹´«Ã½É«ÇéƬ Biology journals. This is not meant to be a comprehensive article but rather a showcase of promising preventative and treatment measures.

Electrical heart diseases: Faulty wiring

Electrical heart diseases are responsible for a large number of sudden, unexpected deaths. Like clocks, our hearts rely on electricity to produce rhythmic movements over time. Just as a clock ticks 60 seconds per minute, the resting heart rate typically is 60 beats per minute, each beat ejecting oxygenated blood into the body. Unlike a clock, though, a healthy beating heart can adjust its activity up to 120 beats per minute under normal conditions.

There is a wide range of heart rates that fall within the normal window for healthy hearts, and this is to allow the body to adjust its circulation rate of oxygenated blood to keep up with the body’s metabolic demands. Heart rates fluctuate based on situation. During sleep, resting heart rates are low because our body processes slow down. During periods of exercise, stress or excitement, heart rates are high because our body processes speed up. Various other factors such as temperature, body size and caffeine also can affect heart rate.

The rhythmic production of these electrical signals begins in the upper right chamber of the heart and propagates down into the lower chambers. With each beat, mechanical contractions occur and force blood out into the body’s circulatory system. However, for a variety of reasons, sometimes these electrical activities can go haywire. In these situations, either the electrical signals do not generate properly (i.e., rhythm disorders) or the electrical signals do not travel properly (i.e., conduction disorders) or both.

Rhythm disorders

When heart rates deviate outside of the normal rhythmic range, the heart experiences what is called an arrhythmia. Generally, a heart rate lower than 60 beats per minute is known as bradycardia, and a heart rate higher than 100 beats per minute is known as tachycardia. If these events are rhythmic (meaning the beat-to-beat rate is consistent over a period of time), the body is simply experiencing an exceedingly slow or fast metronome. However, if these events are abnormal or become dyssynchronous, the outcomes can be dangerous and potentially lethal.

When rhythmic dyssynchrony occurs in the atria (the two upper chambers of the heart), this may be only bothersome or uncomfortable. When rhythmic dyssynchrony occurs in the ventricles (the two lower chambers of the heart), the situation may be life-threatening. The ventricles are responsible for simultaneously pushing deoxygenated blood out into the lungs and oxygenated blood out into the body in a matter of milliseconds. If the ventricles do not electrically excite at the consistent rhythm that is set by the heart’s natural pacemaker (also thought of as the metronome), they can instead “quiver” to such an extent that blood cannot be pumped adequately and the body cannot receive the oxygen it needs to function. This quivering type of arrhythmia is known as ventricular fibrillation. Ventricular fibrillation events need to be stopped quickly. If sustained for more than a few minutes, these episodes can lower blood pressure substantially and cause cardiac arrest or even death.

Conduction disorders

In addition to problems with heart rate dyssynchrony, problems can arise when there is a so-called “short in the circuit.” Two common examples of conduction system disorders are bundle branch block, or BBB, and total heart block.

BBB is a disorder with the bundle branches — the specialized strings of cells that line the inner walls of the ventricles. Under normal conditions, bundle branches propagate electrical signals to spark healthy and rhythmic mechanical pumping. In a conduction disorder, a block in either one of the two bundle branches can lead to electrical dyssynchrony and trigger a ventricular arrhythmia.

Like BBB, total involves a blockage of conduction system, but the blockage occurs at a crucial junction in the heart — a place called the atrioventricular node. The atrioventricular node is a specialized group of cells that sits between the upper and lower chambers of the heart, serving as an electrical moderator to give the ventricles adequate time to receive blood from the atria. The severity of total heart block can be broken down in tiers.

• First-degree is the least serious. Here, electrical impulses pass through the AVN, but they move more slowly than normal. This type of heart block may not come with any noticeable systems but still can be seen in ECG scans.

• Second-degree heart block is more severe. Here, electrical impulses pass through the atrioventricular node as well, but some beats intermittently are blocked. These occasional dropped beats can manifest as heart palpitations, chest pain or fainting.

• Lastly, third-degree heart block occurs when the electrical signals through the atrioventricular node are blocked completely. This is the most serious form of total heart block. The heart beat will become irregular and unreliable, and if left untreated, third-degree heart block can lead to cardiac arrest.

Structural heart diseases: Faulty mechanics

Structural heart diseases are defects or disorders that affect the heart’s overall anatomy. These can occur in the walls, muscles or valves and can be inherited (i.e., present from birth) or acquired (i.e., developed over time). More than 10% of adults 75 years and older live with acquired structural heart disease.

Cardiomyopathy is the general term used to describe stiff or enlarged chamber walls. It results in inefficient blood circulation and can weaken the heart muscle over time. Cardiac amyloidosis is a specific disorder of the heart muscle in which protein deposits called amyloids infiltrate tissues. This type of disorder can cause excessive buildup of fluid in the body, which can lead to shortness of breath or swelling of the legs and abdomen.

Structural heart disease occurring in the valves is another problem. In a healthy heart, there are four valves (mitral, tricuspid, aortic and pulmonary), which open and close smoothly to allow blood to pass through. Like doors of a house or bridges to an island, these valves must function properly to keep things moving. If these doors are rusty or stiff, flow may be compromised. Stiff valves are called stenosis. Valves that permit blood flow in the wrong direction are called regurgitant. Leaflet tears, calcification and atheroma (fatty deposits) are other conditions that also can affect the function of valves.

Vascular heart diseases: Faulty flow

Vascular heart diseases may be the type of heart failure you are most familiar with. Know someone with a stent? Vascular heart disease. Know someone who has had coronary artery bypass graft surgery? Vascular heart disease. This type of heart disease encompasses any condition that affects blood vessels of the heart. They are common and can be serious.

Examples of vascular heart diseases include atherosclerosis (plaque buildup inside arteries), coronary artery disease (blockage of an artery) and aortic aneurysms (ballooning of the aortic walls). In all conditions, healthy blood flow may be compromised. If left untreated, the severity of these diseases can increase significantly and lead to heart attacks or sudden death. Some signs of vascular heart disease include chest pain, fainting, dizziness, fatigue, loss of responsiveness, abnormal breathing, shortness of breath, loss of consciousness and kidney dysfunction.

Causes and treatments

Though there are many types of heart diseases and the nature of these diseases varies widely, underlying causes are often the same. Some of the most common causes of heart disease include:

• Genetics.

• Smoking.

• Alcohol use.

• Poor diet.

• Drugs.

• Age.

• Stress.

• Physical inactivity.

• High blood pressure.

• High cholesterol.

• . 

Preventative measures and treatments

Fortunately, according to the Centers for Disease Control and Prevention, through healthy lifestyles and appropriate medical intervention.

In choosing a healthy lifestyle, it is recommended to eat healthy foods and choose healthy drinks. Low-sodium diets and limited alcohol use can help you maintain low blood pressures. High-fiber foods and foods low in saturated and trans fats can help prevent high cholesterol.

Also, it is suggested to maintain a healthy weight, get regular physical activity and avoid smoking. High body weights can put stress on your heart and block blood vessels from adequate circulation, but physical activity can help you maintain a healthy weight and lower your blood pressure, blood cholesterol and blood sugar levels.

By taking charge of health care measures, you can take preemptive steps to lower your risk of heart disease. Examples of being proactive in this sense include checking your cholesterol every four to six years, controlling your blood pressure through lifestyle changes, managing diabetes if necessary, taking medicines as directed and working with your health care team if you have any questions.

In addition to lifestyle changes, the World Health Organization asserts that through proper health coverage.

• Hypertension programs, when implemented efficiently, can reduce the incidence of vascular disorders such as coronary artery disease and stroke.

• Access to proper medication can mitigate and treat electrical disorders of the heart. Basic medicines such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors and statins treat numerous forms of heart disease and should be made available throughout the world.

• Access to appropriate technology is also important. Implantable cardiac defibrillators, permanent pacemakers and left ventricular assist devices are imperative to treat some of the most severe diseases and restore proper blood flow.

• Minimally invasive surgical operations such as coronary artery bypass grafting, valve repair/replacement, radiofrequency ablation, balloon angioplasty and stent placement also can be life-saving options for those suffering from negative symptoms.

• Finally, heart transplantation is a viable option for those with end-stage heart failure.

To ensure worldwide access to the myriad life-saving procedures, however, investments in strengthening health systems are imperative for reducing the incidence of this global killer.

Advocacy and governmental action

This year, for World Heart Day is based on three key pillars: equity, prevention and community. The campaign website asks the world to #UseHeart to overcome this expansive healthcare crisis and to “use your knowledge, compassion and influence to make sure you, your loved ones and the communities you’re part of have the best chance to live heart-healthy lives.”

I would like to take a moment here and hark back to the introductory analogy of this paper. I chose Washington, D.C., as an example because, in addition to being the heart of our country, it can play a vital role in mitigating heart disease in the United States and beyond.

Proper policy measures can save lives. By reducing risk factors such as tobacco use, unhealthy diets and physical inactivity, our government can help prevent at least 80% of the premature deaths from heart disease and stroke in our country.

Greater access to healthy foods in low-income neighborhoods and improved measures for reaching environmental justice can have far-reaching effects, including improved eating habits, more vibrant communities and fewer deaths.

The responsibility for curbing heart disease does not solely have to lie with the individual. More scientific research in heart failure mechanisms can lead to better understandings of the disease and improve treatment modalities. More awareness of the risks of tobacco can prevent unnecessary heart disease.

As a citizen, you can call on your local representatives to help solve this health crisis. You can educate your neighbors on heart-healthy foods. You can join or start a local exercise group. And you can make sure you and your loved ones know you have both a chance for and a right to heart-healthy futures.