When your heart beats too fast, it’s called tachycardia. The medical definition is a resting heart rate above 100 beats per minute, compared to the normal range of 60 to 100. Tachycardia isn’t always dangerous. Your heart speeds up naturally during exercise, stress, or a fever. But when it happens without an obvious reason, or keeps happening, it can signal an underlying problem worth investigating.
Why Your Heart Speeds Up
Your heart rate is controlled by electrical signals that tell it when to contract. Tachycardia happens when something disrupts those signals or pushes your body to demand more blood flow. The most common version, called sinus tachycardia, is your heart responding normally to a stressor. Fear, nervousness, intense exercise, dehydration, fever, and certain drugs (including caffeine) can all push your heart rate above 100 beats per minute. In these cases, your heart is doing exactly what it’s supposed to do, and the rate comes back down once the trigger passes.
Less commonly, a fast heart rate points to something that needs treatment: anemia, an overactive thyroid, heavy bleeding, or damage to the heart muscle itself. In these situations, the fast rate is a symptom of the underlying condition rather than a standalone problem.
Types of Tachycardia
Not all fast heart rhythms are the same. The two broad categories are based on where in the heart the faulty electrical signals originate.
Supraventricular tachycardia (SVT) starts in the upper chambers of the heart. It tends to be less severe and is more common in younger people. During an episode, your heart rate can spike to 250 beats per minute or higher, but it often returns to normal within a few minutes on its own. If it lasts longer, you may feel dizzy or lightheaded.
Ventricular tachycardia (VT) starts in the lower chambers and is more common in older adults with existing heart disease. A brief burst lasting only a few seconds may cause no symptoms at all. But sustained VT, lasting more than 30 seconds, can drop your blood pressure enough to cause dizziness, shortness of breath, or fainting. VT is the more dangerous type because it can deteriorate into ventricular fibrillation, where the heart quivers instead of pumping, leading to cardiac arrest. Most cases of VT are caused by damage from a prior heart attack, heart failure, or valve disease.
What It Feels Like
Some people with tachycardia feel nothing at all and only discover it during a routine checkup. Others notice a pounding, fluttering, or racing sensation in the chest, often described as palpitations. You might also feel short of breath, lightheaded, or unusually fatigued. Some people experience chest tightness or a sense that something is “off” without being able to pinpoint exactly what.
The intensity of symptoms often depends on how fast the rate is, how long the episode lasts, and whether you have any existing heart conditions. A heart rate of 110 during a stressful meeting feels very different from a sudden jump to 200 while you’re sitting on the couch.
Slowing Your Heart Rate at Home
For certain types of fast heart rhythms, particularly SVT, simple physical techniques called vagal maneuvers can sometimes reset your heart’s rhythm. These work by stimulating the vagus nerve, which acts as a brake on heart rate. They have a 20% to 40% success rate for converting a fast rhythm back to normal.
- Valsalva maneuver: Lie on your back, take a deep breath, then try to exhale forcefully with your mouth and nose closed for 10 to 30 seconds. It should feel like blowing air into a blocked straw.
- Cold water dive reflex: Take several deep breaths, hold the last one, and submerge your entire face in a container of ice water for as long as you can tolerate. If that’s impractical, pressing an ice-cold wet towel firmly against your face can produce a similar effect.
- Applied abdominal pressure: Lie on your back and fold your legs toward your face, then take a breath and strain for 20 to 30 seconds.
These techniques are safe for most people during an SVT episode, but they won’t help with ventricular tachycardia or other serious arrhythmias. If the episode doesn’t resolve quickly, or if you feel chest pain, severe dizziness, or like you might faint, that situation requires emergency care.
How Tachycardia Is Treated
Treatment depends entirely on the type and cause. If a fast heart rate is driven by dehydration, anxiety, or too much caffeine, the fix is addressing that trigger. Sinus tachycardia caused by an overactive thyroid or anemia resolves when the underlying condition is treated.
For recurring SVT or VT, medications that slow the heart’s electrical signals are often the first step. Beta-blockers are the most commonly used class. They work by reducing the heart’s response to adrenaline, lowering both the frequency and severity of episodes. These medications need to be tapered off gradually rather than stopped suddenly, because abrupt withdrawal can cause a rebound spike in heart rate and blood pressure.
When medication isn’t enough, a procedure called catheter ablation can target and destroy the small area of heart tissue responsible for the abnormal electrical signals. For ventricular tachycardia, this procedure has acute success rates of roughly 75% to 82%, depending on the type of underlying heart condition. Success rates tend to be somewhat higher in patients whose VT stems from prior heart attack damage compared to other forms of heart disease.
Risks of Leaving It Untreated
An occasional episode of tachycardia in an otherwise healthy person is usually harmless. But a heart that runs too fast for extended periods has to work harder with each beat, and over time, that extra workload can weaken the heart muscle. This condition, called tachycardia-induced cardiomyopathy, can lead to heart failure if the fast rate isn’t brought under control. The heart essentially exhausts itself.
Ventricular tachycardia carries the most immediate risk. Because it can degrade into ventricular fibrillation, sustained VT is a medical emergency. Even in people who feel fine between episodes, recurrent VT with underlying heart disease significantly raises the risk of sudden cardiac arrest. That’s why VT is typically treated more aggressively than SVT, and many patients with recurrent VT receive an implantable defibrillator as a safety net alongside other treatments.