Tachycardia is a heart rate faster than 100 beats per minute at rest. Your heart normally beats 60 to 100 times per minute, so tachycardia means the electrical signals controlling your heartbeat are firing too quickly, too often, or along the wrong pathways. Sometimes this is perfectly normal, like during exercise or when you’re stressed. Other times it signals an underlying problem that needs attention.
Why the Heart Speeds Up
Your heart has a built-in pacemaker, a cluster of cells in the upper right chamber that sends out electrical signals to trigger each beat. These signals travel through a specific pathway, coordinating the upper and lower chambers so they pump blood in rhythm. Tachycardia happens when something disrupts this system.
Three main electrical problems can cause it. First, the pacemaker cells can become overactive and fire faster than they should. Second, extra electrical impulses can develop after a normal heartbeat, essentially creating bonus signals that push the heart to beat again before it’s ready. Third, and most commonly in dangerous forms of tachycardia, an electrical signal can get stuck in a loop. Instead of traveling through the heart once and stopping, the signal circles back to where it started and triggers another beat, then another, creating a self-sustaining circuit of rapid firing.
Sinus Tachycardia vs. Problem Tachycardia
Not all fast heart rates are cause for concern. Sinus tachycardia is the normal, expected increase in heart rate from exercise, stress, fear, fever, or medications. Your heart’s natural pacemaker is working correctly; it’s just responding to your body’s demand for more blood flow. This type resolves on its own once the trigger passes.
The forms that warrant medical attention involve abnormal electrical activity. These fall into two broad categories based on where in the heart the problem originates.
Supraventricular tachycardia (SVT) starts in the upper chambers of the heart, above the ventricles. It’s generally less dangerous, though episodes can be frightening and uncomfortable. Many people with SVT live normal lives with occasional episodes that resolve on their own or with simple techniques.
Ventricular tachycardia (VT) starts in the lower chambers, the ones responsible for pumping blood to your lungs and the rest of your body. VT is more serious because the lower chambers do the heavy lifting of circulation. When they beat too fast, they can’t fill with enough blood between beats, which means less blood reaches your organs. In some cases, VT can deteriorate into ventricular fibrillation, a chaotic rhythm that is life-threatening without immediate treatment.
Common Causes and Triggers
Several everyday substances and habits can trigger episodes. Caffeine stimulates the nervous system and raises levels of stress hormones in the blood, which directly affects the heart’s electrical activity. One randomized trial found that participants who consumed coffee had a 54% increase in premature heartbeats compared to those who avoided caffeine. Energy drinks, which contain between 80 and 300 mg of caffeine per serving along with sugar and other stimulants, can raise both heart rate and blood pressure.
Alcohol and smoking also increase the risk. The most commonly self-reported triggers among people with atrial fibrillation (a related rhythm disorder) are alcohol, caffeine, exercise, and lack of sleep. People who smoke or drink heavily may have a heightened baseline risk of rhythm problems.
Beyond lifestyle triggers, several medical conditions can drive tachycardia:
- Hyperthyroidism: an overactive thyroid floods the body with hormones that speed up metabolism, including heart rate
- Anemia: with fewer red blood cells carrying oxygen, the heart compensates by beating faster
- Lung disease: poor oxygen exchange puts extra demand on the heart
- High blood pressure and heart disease: structural changes to the heart can disrupt its electrical pathways
- Heart failure: a weakened heart may race to maintain adequate blood flow
- Electrolyte imbalances: minerals like potassium and calcium are essential for normal electrical signaling in the heart
What It Feels Like
The hallmark symptom is palpitations, a racing, pounding sensation in your chest. Some people describe it as a flip-flopping feeling, while others simply notice their heart beating unusually fast or hard. Beyond palpitations, tachycardia can cause chest pain, lightheadedness, shortness of breath, and in more severe episodes, fainting. Some people have no symptoms at all and only discover the condition during a routine checkup or when wearing a fitness tracker.
The severity of symptoms often depends on how fast the heart is going, how long the episode lasts, and whether you have other heart conditions. A brief episode at 110 beats per minute may feel like mild fluttering. A sustained episode at 180 beats per minute can make you dizzy, short of breath, and unable to function normally.
How Tachycardia Is Diagnosed
The most straightforward test is an electrocardiogram (EKG), which records your heart’s electrical activity through sticky patches placed on your chest. It takes just a few minutes and can show whether your heart is beating too fast or in an abnormal pattern. Some smartwatches can now perform basic EKG readings, which is how some people first catch an irregular rhythm.
The challenge is that tachycardia often comes and goes. If your heart is beating normally during the EKG, the test won’t capture the problem. That’s where portable monitors come in. A Holter monitor is a small device you wear for a day or more that continuously records your heart rhythm during normal activities. An event monitor works similarly but records only when you press a button during symptoms, or when it automatically detects an abnormal rhythm.
Depending on the situation, your doctor may also order an echocardiogram (an ultrasound of the heart) to check how well the chambers and valves are working, a chest X-ray, or a cardiac MRI. The MRI is particularly useful for identifying the source of ventricular tachycardia. In some cases, a coronary angiogram is done to check for blocked blood vessels that could be causing the rhythm problem.
A tilt table test may be used if tachycardia is causing you to faint. You lie flat while your heart rate, rhythm, and blood pressure are monitored, then the table is gradually tilted upright to see how your cardiovascular system responds to the position change.
Stopping an Episode
For certain types of SVT, physical techniques called vagal maneuvers can sometimes break the cycle by stimulating the vagus nerve, which slows electrical conduction through the heart.
The Valsalva maneuver is the most common. You lie on your back, take a deep breath, and bear down as if straining, blowing hard against a closed throat for 10 to 15 seconds. A practical variation involves blowing into a syringe hard enough to push the plunger. A modified version adds a step: immediately after straining, someone lowers you flat and raises your legs to a 45 to 90 degree angle, holding that position for 45 seconds to a minute. This modified approach tends to be more effective.
The diving reflex is another option. You take several deep breaths, hold the last one, and submerge your face in a basin of cold water. The cold triggers a reflex that slows the heart. For infants or small children, a bag of ice water is held gently against the forehead and nose for up to 30 seconds.
These techniques work best for SVT and are not appropriate for ventricular tachycardia, which typically requires medical intervention.
Long-Term Management
When tachycardia recurs or is caused by an underlying condition, treatment focuses on controlling heart rate and addressing the root cause. Medications that block electrical conduction through the heart are commonly used. Beta-blockers reduce the effect of stress hormones on the heart. Calcium channel blockers relax blood vessels and slow the heart by preventing calcium from entering heart and artery cells, which reduces how forcefully they contract.
For people with structural heart problems, keeping the heart rate controlled is especially important. In conditions like mitral stenosis (a narrowed heart valve), tachycardia shortens the time the heart has to fill between beats, which can lead to fluid backing up into the lungs and dangerously low blood pressure. In hypertrophic cardiomyopathy, where the heart muscle is abnormally thick, tachycardia can trigger a sudden worsening because the thickened muscle needs more time to fill properly.
When medications aren’t enough, procedures like catheter ablation can destroy the small area of heart tissue responsible for the abnormal electrical signals. For life-threatening ventricular rhythms, an implantable defibrillator can detect dangerous episodes and deliver a corrective shock automatically. In acute emergencies where tachycardia causes dangerously low blood pressure, synchronized electrical cardioversion (a controlled shock delivered to the chest) can reset the heart’s rhythm.
What Happens if It Goes Untreated
A heart that races chronically is a heart working overtime. Over months or years, sustained tachycardia can weaken the heart muscle because it never gets adequate rest between beats. This can progress to heart failure, where the heart can no longer pump blood efficiently. The risk of blood clots also increases with certain types of tachycardia, particularly atrial fibrillation, because blood can pool in the upper chambers when they quiver instead of contracting fully. Those clots can travel to the brain and cause a stroke. People with preexisting atrial fibrillation face higher risks of death, heart failure, and stroke within 30 days of surgery compared to people without it, highlighting how significantly this condition compounds other health stresses.
The good news is that most forms of tachycardia are manageable. Identifying triggers, treating underlying conditions, and using the right combination of lifestyle changes and medical therapy can keep your heart rate in a safe range and prevent long-term damage.