What tachycardia means
Tachycardia is the medical term for a resting heart rate that exceeds 100 beats per minute (BPM). In a healthy adult at rest, the normal heart rate ranges from 60 to 100 BPM. When the rate climbs above that threshold without a physiological reason like exercise, clinicians call it tachycardia.
The word is built from two Greek roots: tachys, meaning fast, and kardia, meaning heart. You'll see this same Greek root in other medical terms — bradycardia (slow heart rate) uses the opposite prefix, brady, meaning slow.
How to pronounce tachycardia
The pronunciation that trips most students: tak-ih-KAR-dee-uh. Break it into syllables: tach · y · car · di · a. The stress lands on the third syllable, "CAR."
Common mispronunciation: "tay-kih-KAR-dee-uh" — the "tach" sounds like "tack," not "take."
Types of tachycardia
Not all tachycardia is the same. Clinicians classify it by where in the heart the abnormal rhythm originates:
| Type | Origin | Clinical significance |
|---|---|---|
| Sinus tachycardia | Sinoatrial (SA) node — normal pacemaker | Usually benign; triggered by fever, dehydration, pain, anxiety, exercise |
| Supraventricular tachycardia (SVT) | Above the ventricles (atria or AV node) | Often causes palpitations; generally not immediately life-threatening |
| Atrial fibrillation (A-fib) with rapid ventricular response | Chaotic atrial activity | Common; stroke risk; requires rate control or rhythm control |
| Ventricular tachycardia (V-tach) | Ventricular myocardium | Potentially life-threatening; can degrade into ventricular fibrillation |
Common causes
Tachycardia has a wide range of causes, from benign to emergent:
- Physiologic: Exercise, stress, caffeine, fever, pain, dehydration
- Medical: Anemia, hyperthyroidism, pulmonary embolism, sepsis, heart failure
- Pharmacologic: Stimulants, certain decongestants, beta-agonist inhalers, cocaine
- Cardiac: Underlying arrhythmia, myocardial infarction, cardiomyopathy
How tachycardia is diagnosed
Diagnosis starts with the clinical context. A heart rate of 110 BPM in someone who just climbed stairs is expected. The same rate in a resting patient with chest pain and diaphoresis is an emergency. Workup typically includes:
- 12-lead ECG: Identifies the type of tachycardia and the rhythm origin
- Labs: CBC (anemia), thyroid panel, electrolytes, troponin if cardiac cause suspected
- Telemetry monitoring: Continuous monitoring in hospitalized patients
- Echocardiogram: Assesses structural heart disease if arrhythmia is recurrent
How clinicians use the term
In clinical practice, you'll hear tachycardia used precisely — often with a modifier that tells you where the rhythm comes from or what the rate is:
"The patient presented with palpitations and was found to be in SVT with a rate of 170." — Emergency physician to cardiologist
"She's tachycardic to the 120s, febrile, and hypotensive — this is SIRS." — Internal medicine resident on rounds
"V-tach, no pulse — start CPR and charge the defibrillator." — Code team leader
Tachycardia vs. bradycardia
The opposite of tachycardia is bradycardia (bray-dee-KAR-dee-uh) — a resting heart rate below 60 BPM. Both can be normal in certain populations: trained endurance athletes commonly have resting rates in the 40s (bradycardia) and may hit 180+ during hard exercise (tachycardia). Context always matters.
Frequently asked questions
What heart rate is considered tachycardia?
A resting heart rate above 100 beats per minute meets the definition. During exercise or emotional stress, higher rates are expected and normal. The clinical concern is tachycardia at rest or tachycardia that is disproportionate to the level of activity.
Is tachycardia always serious?
No. Sinus tachycardia from fever, dehydration, or anxiety is very common and resolves when the underlying cause is treated. Ventricular tachycardia is a medical emergency. The type and clinical context determine the urgency.
How do you treat tachycardia?
Treatment depends entirely on the cause and type. Sinus tachycardia is treated by addressing the underlying trigger (hydrate for dehydration, treat the fever). SVT is often terminated with vagal maneuvers or IV adenosine. V-tach with a pulse may require antiarrhythmics or synchronized cardioversion. V-tach without a pulse requires immediate defibrillation.
What does "tachycardic" mean?
"Tachycardic" is the adjective form. When a clinician says "the patient is tachycardic," they mean the patient currently has tachycardia — a heart rate over 100 BPM.
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