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Originally published January 13, 2026
Last updated January 13, 2026
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We all know what it’s like to feel our hearts race or skip a beat. Sometimes, like when meeting someone you like for the first time, it can even feel exciting.
But according to Ivan C. Ho, MD, director of cardiac electrophysiology at the USC Cardiac and Vascular Institute, part of Keck Medicine of USC, “Whenever your heart’s rhythm is fast, slow or irregular, that means its ticker is out of sync.”
And that means you’re experiencing a heart arrhythmia. But don’t let that knock you off pace: An irregular heartbeat is something to be aware of, but it isn’t necessarily cause for concern.
As Dr. Ho noted, your heart has its own pacemaker.
It’s a cluster of cells in the heart’s upper-right chamber called the sinoatrial node (SA), and, as Dr. Ho says, “It started beating when you were conceived and stops when you die. It’s what speeds up the heart when you’re excited and slows it down when you’re relaxed or sleeping.”
That built-in flexibility is a feature, not a bug, as it allows our bodies to respond to changing situations. “For example,” Dr. Ho says, “if a tiger is running after you, you’ll want to run fast, and your heart rate will have to rise to support that.”
But if your heart strays from its normal cadence of roughly 60 to 100 beats per minute too frequently or for too long, something more than its inherent flexibility may be at work.
Cadences slower than the norm are classified as bradyarrhythmias. Meanwhile, those that are atypically fast are called tachyarrhythmias.
But whatever the speed, Dr. Ho says, “Whether or not an arrhythmia is clinically relevant depends on the arrhythmia type and how we interpret it in the context of a patient’s unique condition.”
The good news is that most heart arrhythmias are benign, causing symptoms that, though disruptive, leave little, if any, lasting harm.
Consider, for example, the case of a 19-year-old college sprinter who experiences an especially high heart rate, shortness of breath and dizziness during and after a tough track session. Believe it or not, Dr. Ho says, this type of episode — known as supraventricular tachycardia (SVT) — isn’t uncommon, and usually isn’t dangerous, either.
However, he continues, “Some arrhythmias can be dangerous. A ventricular tachycardia, in the context of someone with heart disease or who already had a heart attack, could be lethal and, in fact, is the number one cause of sudden cardiac death.”
Atrial fibrillation is another common arrhythmia that can be harmless and even go unnoticed in some patients, but in those with conditions like high blood pressure, diabetes, coronary artery disease or serious valvular heart disease, it can be lethal. “The same diagnosis can be impactful to different degrees for different patients,” Dr. Ho underlines.
The lesson? Take note of the following symptoms, and pay attention to when and how often they occur:
As for when to consult a physician, Dr. Ho urges seeking emergency care if symptoms feel urgent. If they’re more chronically worrisome, however, he suggests starting with a visit to your primary care doctor, who may perform an EKG (electrocardiogram) to evaluate your heart’s electrical activity.
Should your doctor refer you to a cardiologist for further testing, you might receive an echocardiogram to see if your heart is structurally sound, as well as what Dr. Ho describes as an “ambulatory monitor”: a small device — often a skin patch — that records your heart’s rhythm around to clock to catch any “off” beats when they happen.
Even if your doctor diagnoses an arrhythmia, it may not warrant treatment. If it does, options vary from simple medications to advanced procedures.
Case in point: A patient with a benign atrial fibrillation that strikes every couple months and lasts an hour or so when it does might respond well to the “pill-in-the-pocket” approach in which the patient keeps a fast-acting medication on hand to pop whenever the arrhythmia starts.
But if the patient’s arrhythmias happen so frequently and rapidly that even a fast-acting pill can’t stop them in time, maintenance might work better. “That means that regardless of how you feel when you wake up,” Dr. Ho explains, “you take a pill to build up a level of medication in your system that suppresses the arrhythmia and reduces the probability of it coming up.”
And if medications aren’t appropriate for a patient, Dr. Ho continues, “We may proceed with what we call an electrophysiology study catheter ablation.”
These minimally invasive, inpatient procedures allow the doctor to insert a catheter with a high-fidelity electrical recording tip into the patient’s heart in order to recreate the arrhythmia. “It’s like when your car is making funny noises and your mechanic takes it for a test drive to hear them and figure out what’s going on,” Dr. Ho says.
“Once we determine the mechanism causing the arrhythmia,” he continues, “we use real-time intracardiac ultrasound and a sophisticated three-dimensional anatomic map of the heart to pinpoint the location of the short circuit causing the arrhythmia, and then we apply a small amount of energy to that area to terminate the short circuit.”
Physicians come to Keck Medicine of USC specifically to train in this procedure, Dr. Ho says, adding that “We have a very mature and expanding program with highly trained fellows, and we also perform a high volume of these procedures. One of the most important factors for success is operator experience.”
That should put anyone’s heart at ease. After all, Dr. Ho says, “The diagnosis of an out-of-sync heart rhythm can be scary. But we’ve come very far in the past 10 to 15 years. And we’re getting better at finding explanations and treatments for almost everything.”
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