John often experiences unanticipated attacks of intense fear. during these episodes, he feels like fainting and has trouble catching his breath. john cannot identify the source of his feelings and worries that he might die of heart failure. in the context of psychological disorders, john is exhibiting the symptoms of:

panic disorder

Explanation:

Panic disorder is a kind of anxiety disorder. The person experience a feeling of terror and fear when there is actually no real danger. The person also feels anxiety, worry and distress in panic disorder. The other symptoms of panic disorder includes the rapid heart rate, sweating, shaking or trembling, shortness of breath, chills and hot flashes.

According to the given situation, the symptoms seen in John resemble that of panic disorder.