Dysrhythmia refers to any abnormality in the heart’s rhythm, including irregular, too fast, or too slow heartbeats, caused by disturbances in the electrical conduction system. It matters clinically because dysrhythmias can impair cardiac output and lead to symptoms such as palpitations, syncope, or sudden cardiac arrest. Atrial fibrillation is a common example, increasing the risk of stroke due to thrombus formation in the atria.