Second-degree atrioventricular block refers to a condition in which the electrical signals from the upper chamber of the heart, the atria, are delayed or blocked from reaching the lower chamber, the ventricles. This results in an abnormal heart rhythm, or arrhythmia. Other medical terms used to describe this condition include type II atrioventricular block, Mobitz type II block, and AV block 2. Symptoms of second-degree atrioventricular block may include dizziness, fainting, palpitations, and shortness of breath. Treatment may involve medication, pacemaker implantation, or other interventions depending on the severity of the condition. It is important to seek medical attention promptly if you experience any symptoms of heart rhythm abnormalities.