Tachikardia

Tachycardia refers to a heart rate that is faster than normal at rest. In adults, a resting heart rate above about 100 beats per minute is commonly used to define tachycardia, though normal rates vary with age and context. Tachycardia can arise from the heart’s natural pacemaker functioning abnormally or from disordered electrical activity in the heart.

Types include sinus tachycardia, which is a normal physiological response to factors such as exercise, fever, dehydration, or sympathetic stimulation; supraventricular tachycardia (SVT), originating from the atria or atrioventricular node; and ventricular tachycardia (VT), which originates from the ventricles and can be life-threatening. Paroxysmal tachycardias begin and end abruptly, whereas persistent forms last longer.

Common causes encompass physiological conditions (exercise, fever, anxiety), medical issues (anemia, hyperthyroidism, heart failure, ischemia), medications or substances (caffeine, stimulants, withdrawal from certain drugs), and electrolyte disturbances.

Signs and symptoms vary; some individuals experience palpitations, dizziness, chest discomfort, shortness of breath, or fainting, while others are asymptomatic. Diagnosis relies primarily on electrocardiography (ECG) to classify the rhythm, with additional testing such as thyroid function tests, electrolyte measurements, echocardiography, and rhythm monitoring (Holter or event monitors) as needed.

Management depends on the tachycardia type, stability, and underlying cause. Unstable tachycardia requires urgent cardioversion. Stable SVT may respond to vagal maneuvers or adenosine; other SVTs may require beta-blockers, calcium channel blockers, or catheter ablation. VT often requires antiarrhythmic therapy, electrical therapy if unstable, and may necessitate an implantable cardioverter-defibrillator (ICD) or ablation. Treating the underlying condition is essential for sinus tachycardia.

Prognosis varies with cause and cardiac health; chronic tachycardia can contribute to cardiomyopathy, and VT associated with structural heart disease carries higher risk.