A panic attack is not a disorder in itself, but a syndrome, or cluster of symptoms that may be part of a number of disorders. It is a cardinal feature of panic disorder, but can be caused by almost any anxiety disorder (with the exception of Generalized Anxiety Disorder).
A panic attack begins quickly, and peaks within 10 minutes. The entire attack usually lasts no more than 20 minutes, and attacks that occur for over an hour are very rare. However, once the attack is finished, patients may have residual symptoms as they recover from what is a very frightening event.
Symptoms of a panic attack include the following: Palpitations, pounding heart, or increased heart rate, Sweating, Trembling or shaking, Sensations of shortness of breath or smothering, Feeling of choking, Chest pain, Nausea, Dizziness, Derealization (feelings of unreality) or depersonalization, Feeling of losing control/going crazy, Fear of dying, Paresthesias, and Chills. Among these symptoms, the most common, and perhaps most central to the disorder are the pulmonary ones: the feeling of shortness of breath and/or choking.