An arrhythmia is any heartbeat that doesn’t follow the normal rhythm. Your heart might beat too fast, too slow, or with an irregular pattern. Some arrhythmias are brief and harmless, like the occasional feeling that your heart “skipped a beat.” Others are chronic conditions that affect how well your heart pumps blood and may need ongoing treatment.
How Your Heart’s Electrical System Works
Your heart beats because of electrical signals, not muscle memory. A cluster of specialized cells at the top of your heart acts as a natural pacemaker, firing a signal that travels downward through your heart in a specific sequence. That signal first causes the two upper chambers to contract, pushing blood into the two lower chambers. The signal then reaches the lower chambers, which contract to pump blood out to your lungs and body.
An arrhythmia happens when this electrical signal doesn’t get produced properly, doesn’t travel the way it should, or both. The disruption can originate at any point along the pathway: in the pacemaker cells at the top, at the relay point in the middle, or in the branching pathways that reach the lower chambers.
The Three Main Types
Arrhythmias fall into three broad categories based on what the heart rate is doing:
- Tachycardia: A resting heart rate faster than 100 beats per minute. Your heart is beating too quickly to fill with blood efficiently between beats, which can reduce how much blood reaches the rest of your body.
- Bradycardia: A resting heart rate slower than 60 beats per minute. The heart isn’t beating often enough to meet the body’s demand for oxygen-rich blood. (One exception: well-trained athletes often have resting rates below 60 because their hearts pump more blood per beat.)
- Premature heartbeats: Extra beats that fire too early, creating a brief pause followed by a stronger-than-normal beat. This is what people describe as a “skipped” or “fluttering” heartbeat. Premature beats sometimes occur one at a time and sometimes in alternating patterns with regular beats.
Within these categories, there are many specific conditions. The most common is atrial fibrillation, an irregular rhythm originating in the upper chambers. It affects an estimated 10.5 million American adults, roughly 1 in 22 people, and its prevalence has been rising steadily. Between 2005 and 2019, the rate among adults receiving hospital care climbed from about 4.5% to nearly 7%.
What an Arrhythmia Feels Like
Many arrhythmias produce no symptoms at all, especially if they’re brief or mild. When symptoms do appear, they vary depending on whether the heart is beating too fast, too slow, or erratically.
Common sensations include palpitations (a fluttering, pounding, or racing feeling in your chest), dizziness or lightheadedness, shortness of breath, and fatigue that seems out of proportion to your activity level. Some people feel a “thud” in the chest from a premature beat, followed by a moment where the heart seems to pause before resuming.
More serious episodes can cause fainting, chest pain, or a sudden collapse. A racing heart paired with dizziness or lightheadedness, chest pain, or loss of consciousness warrants immediate emergency care.
Common Causes and Triggers
Arrhythmias can result from structural problems with the heart, chemical imbalances in the blood, or external triggers. Coronary artery disease, high blood pressure, and heart valve problems can all alter the heart’s electrical pathways over time by changing the physical structure of the heart tissue. Sleep apnea, thyroid disorders, and diabetes also increase risk.
Electrolyte imbalances play a surprisingly direct role. Minerals like potassium, magnesium, and calcium help regulate the electrical signals in heart cells. When their levels are too high or too low (from dehydration, medications, or kidney problems, for example), the signals can misfire.
Short-term triggers include caffeine, alcohol, stress, fever, and certain over-the-counter cold medications that contain stimulants. Some people notice that arrhythmia episodes follow specific patterns, like after heavy meals or during periods of poor sleep.
How Arrhythmias Are Diagnosed
Because arrhythmias come and go, catching one in the act is the main diagnostic challenge. The most basic tool is an electrocardiogram (EKG), a quick, painless test where sticky sensors on your chest measure the heart’s electrical activity. An EKG can show whether the heart is beating too fast, too slow, or irregularly, but it only captures a snapshot of the moment you’re hooked up.
If your symptoms are intermittent, your doctor may have you wear a Holter monitor, a portable EKG device that records your heart’s activity continuously for a day or more while you go about normal life. For arrhythmias that happen even less frequently, a small loop recorder can be implanted just under the skin to track electrical signals over weeks or months.
A stress test is useful when exercise seems to trigger the problem. You walk on a treadmill or ride a stationary bike while your heart activity is monitored. If you can’t exercise, medication can simulate the effect of physical exertion on your heart.
Treatment Options
Treatment depends entirely on the type of arrhythmia, how severe it is, and whether it poses a risk of complications like stroke or heart failure. Many premature heartbeats need no treatment at all.
For arrhythmias that do require intervention, medication is often the first step. Antiarrhythmic drugs work by stabilizing the electrical signals in heart cells, reducing the frequency or severity of episodes. These are taken as daily pills in most cases.
When medication isn’t enough, ablation is a common next option. During this procedure, a thin tube is guided through a blood vessel to the heart, where small areas of tissue causing the faulty signals are destroyed using heat or cold energy. For atrial fibrillation specifically, tiny scars are created to block the irregular electrical pathways. Recovery typically takes a few days to a week, and many people see significant improvement in their symptoms.
Electrical cardioversion is a planned procedure where a controlled shock resets the heart to a normal rhythm. It’s less intense than the emergency defibrillation you see on TV and is done under sedation.
For chronic or dangerous arrhythmias, implantable devices offer long-term management. A pacemaker sends small electrical pulses to keep the heart beating at a steady rate, which is especially useful for bradycardia. An implantable cardioverter defibrillator (ICD) monitors the heart continuously and delivers a stronger shock if it detects a life-threatening rhythm, essentially preventing cardiac arrest. Both devices are placed under the skin near the collarbone through a relatively minor surgical procedure, and most people resume normal activities within a few weeks.