Hello thanks for asking from HCM for your health related queries I can understand your concern. Sudden onset rapid heart beat or palpitations associated with breathlessness, feeling of fear, feelings that heart would drop down etc are seen most commonly in anxiety, though medical causes like hyperthyroidism can also result in similar symptoms. As these symptoms are persistent and are occurring in episodes so I would advise you to visit a psychiatrist for evaluation and for treatment. Medicines like SSRIs or SNRIs are commonly used in anxiety. Fluoxetine, Sertraline, Paroxetine etc are approved drugs for anxiety. For severe episodic attacks medicines like low dose benzodiazepines can help. Clonazepam, Lorazepam in low doses help to reduce the symptoms and can calm you. Please dont be stressed as most probable cause of your symptoms is anxiety. With medicines your symptoms will improve. Visit a doctor for prescription of these drugs. Thanks, Hope this helps you. Take care. Dr. Seikhoo Bishnoi MD Psychiatry