The rhythm of the heart
Many know that my dear wife Mary is quite an accomplished pianist. In fact, during my long years of training she merged her musical talent and her amazing way with young children and supplemented my meager resident’s salary by teaching music lessons — in addition to her full-time teaching job and raising Kate!
I on the other hand, appreciate music but have minimal talent. In fact, whether it’s at a concert, at home or in the car, when I start tapping my hand or foot in time to the music, Mary inevitably has to gently take my hand or touch my knee to correct my enthusiastic but erroneous beat.
You see, rhythm is an important part of life, and getting it right matters. It propels our musical, artistic and linguistic expression. It governs natural events like the ebbing and flowing of tides and the human sleep pattern. And it is particularly important to the engine of the body’s circulatory system, the heart.
The adult heart has a wide range of resting rates that are considered normal, and it varies from person to person. In general, anywhere from 60 to 100 beats per minute (bpm) can be a healthy heart rate. But when the heart rate drops below 60 bpm, rises above 100 bpm, or becomes irregular, it could be a sign of an arrhythmia (sometimes called dysrhythmia).
Arrhythmia comes in several forms and ranges in severity from innocuous to potentially deadly. In moderate and severe cases, arrhythmia can impede the heart’s ability to pump blood to the rest of the body.
When the heart beats too slowly, it’s called bradycardia. Bradycardia can result from problems with the sinoatrial node, which is the heart’s natural pacemaker, or from other electrical issues, such as trouble with the specialized fibers that make up the conduction pathways. These may become diseased and not allow proper transmission of electrical impulses between the heart’s chambers. Risk factors associated with slow heart rates include metabolic conditions like low levels of thyroid hormone, heart damage due to heart disease or heart attack, and side effects from some medications.
Symptoms of bradycardia can include fatigue and weakness, fainting, shortness of breath, dizziness or lightheadedness, difficulty exercising, confusion, and, in severe cases, cardiac arrest. Complications can include high or low blood pressure, chest pain, fainting and heart failure.
On the other extreme, too high a heart rate is called tachycardia, and there are several types of tachycardia.
Atrial or supraventricular tachycardia is caused by abnormally discharged electrical signals in the heart’s upper chambers, and is more likely to develop in women, children, adolescents, people who consume large quantities of coffee or alcohol, and people who smoke.
Fainting; light headedness or dizziness; palpitations; fluttering in the chest; bounding pulse; pressure, tightness or pain in the chest; shortness of breath; and fatigue are among the symptoms of atrial tachycardia. The most severe cases can lead to unconsciousness and cardiac arrest.
Sinus tachycardia results from faster-than-normal firing of electrical signals from the normal sinoatrial node, causing a heart rate that is abnormally fast but a heartbeat that is regular. This type of tachycardia can be catalyzed by anxiety, fright, severe emotional distress, strenuous exercise, fever, and some drugs.
Ventricular tachycardia is also associated with abnormally firing electrical signals but originates in the heart’s lower chambers. Causes can include abnormal coronary artery blood flow, cardiomyopathy (enlarged, weak heart muscle), side effects of medication, illicit drugs like cocaine, and sarcoidosis (an auto-immune disease of skin and body tissues). Symptoms are similar to atrial tachycardia but also include nausea and a profound sense of impending doom, and cardiac arrest can be a complication in many cases.
One of the most common types of irregular heartbeats, though, is atrial fibrillation, often abbreviated as A-fib or AF, and it occurs when the heart’s upper chambers quiver (fibrillate). This disruption of the heart’s electrical system can stem from many of the same causes listed above as well as serious high blood pressure or heart valve trouble–often the cause can be unknown.
According to the American Heart Association, A-fib affects at least 2.7 million Americans, and severity can range from harmless to life-threatening. In the most serious cases, complications include stroke, heart failure, chronic fatigue and additional heart rhythm disorders.
The good news is that electrocardiography (ECG or EKG) is a non-invasive method of recording the heart’s electrical activity that helps to diagnose arrhythmias and get patients on the right track of treatment. There are a variety of therapies to treat arrhythmias that range from lifestyle changes, wellness practices, medicines, electrophysiology procedures and implanted devices. This look at arrhythmia is the first installment of a three-part series on arrhythmia. Next week’s column will discuss A-fib in greater detail.
Dr. Alfred Casale, a cardiothoracic surgeon, is chief medical officer for surgical services for Geisinger and chair of the Geisinger Heart Institute. For information on alternative treatment for atrial fibrillation, visit https://geisinger.cc/2E2N8n8.