High heart beats and dizziness. What could be the reason for this?

There are a range of different heart problems which can be rectified or managed with surgery which can cause the symptoms you describe. I'm afraid you'll have to give more details or ask your fathers Doctor. Perhaps you are talking about SVT (supra ventricular tachycardia), if medication fails to prevent episodes and they are really becoming a problem then sometimes catheter ablation is suitable for some types of SVT. This involves a wire being passed into the chambers of the heart, via a vein in the groin. The tip of the wire is used to destroy the small section of heart tissue which is triggering the abnormal electrical impulses. This sort of procedure will only work if an exact location is isolated with tests so it can be found by the catheter tip and destroyed.