Panic disorder is manifested by sudden and unpredictable attacks of extreme anxiety with physiological symptoms. People having an anxiety or panic attack can feel as though their body is in an emergency or crisis state; racing heart, hot and cold flashes, nausea and trembling are all physical symptoms of an anxiety or panic attack. Many people report that they thought they were having a heart attack when they were in the grips of panic. Other symptoms can include: dizziness, difficulty breathing or taking a deep breath, feelings of terror or perceptual distortions; one can feel very disconnected from one's body and mind during an anxiety of panic attack.  Often people with panic disorder have gone through medical tests for heart disease, high blood pressure and a range of other physical ailments before a correct diagnosis of panic disorder is made.