What is the cause of tachycardias?
Abnormally fast heart rates are called tachycardias. Tachycardias are caused by rapidly firing electrical signals arising from the walls of the atria or the ventricles. These rapidly firing signals override the signals generated by the SA node and cause the heart to beat too fast. Tachycardias caused by electrical signals from the atria are called atrial tachycardias. Tachycardias caused by electrical signals from the ventricles are called ventricular tachycardias. What are the symptoms of tachycardias? Symptoms of tachycardias include: • Palpitations or fluttering sensations in the heart; • Lightheadedness (due to low blood pressure); • Fainting spells or loss of consciousness (due to low blood pressure); • Fatigue and weakness (due to lack of blood supply); and • A flushing sensation. Please see the Palpitations article of MedicineNet.com for information on the symptoms, causes, and diagnosis of tachycardias. What are life-threatening tachycardias? Two common life-threatening tachyca
