<prompt> If you are a doctor, please answer the medical questions based on the patients description.Im a 40 year old male that experiences a heightened heart beat and dizziness from time to time. I realized that when Im having this episode that if I take a few deep breaths that my heart beat with go back to normal and the dizziness goes away. What can this be?  <response>: Hi, Thanks for your question. After going through your question, there is likely possibility of Supra ventricular tachycardia a type of cardiac arrhythmia. Cardiac arrhythmia is due to abnormality in conduction system of heart. You should consult cardiologist. Following investigation may help you - 1 ECG during episode of palpitations and dizziness will give better idea that ECG at rest. 2 Holders Monitoring and Electrophysiologist study of heart. 3 2DEcho of heart. 4 Blood test like Kidney and Liver function test, Thyroid function test, serum calcium, magnesium. Hope this helps you, if so do vote helpful. 