tachycardi

Tachycardia is a condition characterized by a heart rate that is faster than normal. In adults, a resting heart rate above 100 beats per minute is typically considered tachycardia. It can be a normal response to exercise, fever, pain, anxiety, or dehydration, but it can also indicate an underlying medical problem.

Tachycardia is not a single disorder but a symptom with several types. Sinus tachycardia originates from the normal pacemaker of the heart, the sinoatrial node, and usually reflects a physiological response. Supraventricular tachycardias (SVTs) arise from above the ventricles and include conditions such as AV nodal reentry tachycardia and other atrial tachycardias. Ventricular tachycardia (VT) arises from the ventricles and is often more serious, potentially leading to hemodynamic instability or sudden cardiac death if not treated promptly.

Causes and triggers vary widely. Physiologic factors include exercise, fever, pregnancy, anemia, and dehydration. Pathologic causes can include thyroid disorders, electrolyte imbalances, heart failure, myocardial infarction, pulmonary embolism, lung disease, and the use of stimulants or certain medications. Identifying and treating the underlying cause is a central part of management.

Symptoms may include palpitations, lightheadedness, dizziness, chest discomfort, shortness of breath, or fainting. Some individuals, especially with sinus tachycardia, may have no noticeable symptoms.

Diagnosis relies on electrocardiography (ECG) to determine heart rhythm and rate, with additional tests such as blood work, imaging, or rhythm monitoring to identify causes. Management ranges from observation and treating reversible factors to acute interventions for unstable tachycardia, including vagal maneuvers, medications (beta-blockers, calcium channel blockers, antiarrhythmics), electrical cardioversion, or ablation therapy for specific SVTs or VT. The prognosis depends on the underlying cause and the presence of structural heart disease.