<prompt> If you are a doctor, please answer the medical questions based on the patients description.My husband is complaining of dizzy spells, heart beats rapidly - then pauses for a beat - then returns to normal, also sees a white spot - gets blurry and sight comes back into focus. After a few minutes he goes back to feeling normal as normal is to him. Any idea what might cause this?  <response>: Hello, This can be a cardiac arrhythmia like PSV or atrial fibrillation, in which heart rate suddenly goes up and also suddenly decreases. Blood pressure falls during these episodes and one has dizziness, fainting, blackouts, sometimes syncope. Usually ECG is normal as it is usually done in between the episodes. ECG done during episodes will show abnormality. You will need 24 hour holder monitoring. So visit nearby cardiologist for this investigation. Also, hemoglobin and thyroid test should be done. Ln order to abort such episodes you should try to cough hard. Is there any stress or anxiety associated. Till the time your evaluation is complete, you can ask your local doctor for tab collar LA 20 mg once a day. If none of the above is successful then last option is of electrophysiologist studies which is invasive test which can diagnose and treat the arrhythmia permanently in most of the cases. Hope this helps you and get back if you have any doubts. 