Arrhythmias, defined as irregularities in heart rate and/or rhythm, can be categorized based on heart rate (i.e., slow (bradycardia) or fast (tachycardia)) and heart rhythm. Bradycardic arrhythmias, like sinus bradycardia and heart blocks, occur at heart rates of less than 60 beats per minute and can be due to medications, medical conditions, or conduction disorders. Conversely, tachycardic arrhythmias occur at a heart rate greater than 100 beats per minute and can arise from the atria (supraventricular) or ventricles (ventricular). Patients may have no symptoms at all or complain of symptoms like palpitations, shortness of breath, dizziness, and/or syncope. When suspected, the electrocardiogram is an important initial screening tool to assess for possible arrhythmias. Arrhythmias may be benign or life-threatening, requiring urgent medical intervention, so it is important to thoroughly assess all patients.