Tachycardia means your heart is beating faster than normal while you’re at rest. For adults, that threshold is generally 100 beats per minute. A healthy resting heart rate falls between 60 and 100 beats per minute, so tachycardia starts where the normal range ends.
A fast heart rate isn’t always a problem. Your heart naturally speeds up during exercise, stress, pain, or when you have a fever. That’s your body doing exactly what it should. Tachycardia becomes a concern when your heart races without an obvious reason, or when it happens frequently and causes symptoms.
Why It Happens
Your heart’s rhythm is controlled by electrical signals that follow a specific pathway through the heart muscle. Tachycardia occurs when something disrupts those signals, causing the heart to fire too quickly. The disruption can come from inside the heart itself (a wiring problem, essentially) or from outside forces pushing the heart to work harder.
Common external triggers include fever, anxiety, dehydration, anemia, an overactive thyroid, and certain substances. Alcohol, especially binge drinking, is a recognized risk factor for abnormal heart rhythms. Caffeine is widely considered a potential trigger as well, and combining the two appears to raise the risk beyond either one alone. Nicotine, certain cold medications, and some prescription drugs can also push heart rate up temporarily.
When no underlying cause or trigger explains the fast heart rate, the problem is usually structural or electrical, meaning something about the heart’s own wiring or tissue is generating the abnormal rhythm.
Types of Tachycardia
Sinus Tachycardia
This is the most common and usually the least worrisome type. The heart’s natural pacemaker (the sinus node) fires faster than normal, but the electrical pathway itself works correctly. Exercise, stress, pain, anxiety, and fever all cause sinus tachycardia. It’s a normal physiological response in those situations. It only raises concern when it happens at rest without an obvious explanation.
Supraventricular Tachycardia (SVT)
SVT originates in the upper chambers of the heart. It happens when electrical signals get caught in a loop, circling through an abnormal pathway instead of traveling through the heart once and stopping. The hallmark of SVT is that episodes start and stop abruptly. You might feel perfectly fine, then suddenly your heart jumps to 150 or more beats per minute, and just as suddenly it snaps back to normal. Physical activity or emotional stress can trigger episodes. Some people also experience lightheadedness, chest discomfort, shortness of breath, or anxiety during an episode. SVT is rarely life-threatening, but prolonged episodes lasting hours or days can occasionally lead to dangerously low blood pressure or signs of heart failure.
Ventricular Tachycardia (V-tach)
This is the type that doctors take most seriously. V-tach starts in the lower chambers of the heart, the ones responsible for pumping blood to your body and lungs. Brief episodes lasting only a few seconds may pass without harm, but sustained episodes are life-threatening. V-tach can deteriorate into ventricular fibrillation, a chaotic rhythm where the heart quivers instead of pumping. That leads to sudden cardiac arrest. Symptoms of sustained V-tach include fainting, loss of consciousness, and cardiac arrest. Other complications from recurrent episodes include heart failure and frequent fainting spells.
What It Feels Like
Some people with tachycardia feel nothing at all, especially during brief episodes. When symptoms do occur, the most common include:
- Palpitations: a racing, pounding, or flopping sensation in your chest
- Lightheadedness or dizziness
- Shortness of breath
- Chest pain or discomfort
- Fatigue
- Nausea
- Fainting or near-fainting
The combination of chest pain, difficulty breathing, feeling faint, or a pounding heart warrants immediate medical attention. These can signal that your heart isn’t pumping enough blood to meet your body’s needs.
How It’s Diagnosed
The challenge with tachycardia is catching it in the act. If your heart rate is normal during your appointment, a standard test won’t reveal the problem. That’s why doctors use several tools depending on how often your episodes occur.
An electrocardiogram (ECG or EKG) is the first step. It records your heart’s electrical activity through sticky patches placed on your chest and takes only a few minutes. Some smartwatches can now perform basic ECGs as well. If a standard ECG doesn’t capture an episode, you may wear a Holter monitor for a day or more. This portable device records your heart’s rhythm continuously during daily life. For episodes that happen less frequently, an event monitor lets you press a button when symptoms appear, and some newer devices detect and record irregular rhythms automatically.
An echocardiogram uses sound waves to create moving images of your heart, showing how blood flows through the chambers and valves. This helps identify structural problems that could be driving the fast rhythm. For suspected ventricular tachycardia, a cardiac MRI provides detailed images of heart tissue to pinpoint the cause.
When doctors need to locate the exact source of faulty electrical signals, they use an electrophysiology (EP) study. Thin, flexible tubes are threaded through a blood vessel in the groin to the heart, where sensors on the tips map the heart’s electrical activity in detail. Stress tests, where you walk on a treadmill or ride a stationary bike while being monitored, help identify tachycardias triggered by physical exertion.
How It’s Treated
Treatment depends entirely on which type of tachycardia you have, how often it occurs, and whether it causes symptoms or poses danger.
For SVT, the first thing you’ll likely be asked to try is a vagal maneuver. These are simple physical techniques that stimulate a nerve running from your brain to your abdomen, which can slow your heart rate. The most common is the Valsalva maneuver: you take a deep breath and bear down as if straining, holding for 10 to 15 seconds. Another option involves briefly immersing your face in cold water, which triggers what’s known as the diving reflex. These techniques convert SVT back to a normal rhythm about 20 to 40% of the time. A modified version of the Valsalva maneuver, where you bear down while sitting up and then immediately lie flat with your legs raised, appears to be more effective than the standard approach.
If vagal maneuvers don’t work after two or three attempts, the next step is medication to reset the rhythm. For people with frequent SVT episodes, daily medication to prevent recurrences or a procedure called catheter ablation (which destroys the tiny area of tissue causing the abnormal circuit) may be recommended.
Ventricular tachycardia requires more aggressive treatment. For unstable episodes where blood pressure drops dangerously, electrical cardioversion (a controlled shock to the heart) is performed immediately. People at ongoing risk for V-tach may receive an implantable defibrillator, a small device placed under the skin that monitors heart rhythm and delivers a shock if a dangerous rhythm is detected.
Sinus tachycardia typically doesn’t need direct treatment. The focus is on addressing whatever is causing the heart to race, whether that’s a fever, thyroid problem, anxiety, or substance use.
Heart Rate Norms in Children
The 100-beats-per-minute threshold applies only to adults. Children’s hearts naturally beat much faster, especially in infancy. A newborn’s median heart rate is around 127 beats per minute, rising to roughly 145 beats per minute at about one month of age, then gradually slowing to around 113 beats per minute by age two. Heart rates continue to decline through childhood, eventually reaching adult ranges in the late teenage years. What looks like tachycardia in an adult may be perfectly normal in a toddler.