Heart rhythm disorders, also known as arrhythmias, are a group of conditions that affect the normal beating of the heart. They occur when the electrical impulses that control the heart’s rhythm are disrupted, causing the heart to beat too fast, too slow, or irregularly. Some arrhythmias are harmless, while others can be life-threatening. Symptoms may include palpitations, chest pain, shortness of breath, dizziness, and fainting.