Hello Thanks for posting here. You have definitely got a high heart rate which requires evaluation. Since you said you took GTN SPRAY i suppose you are suffering from heart disease. First of all it is necessary to determine what type of fast heart rate you have regular or irregular. Irregular fast heart rate is called AF or atrial fibrillation. Regular fast heart rate can be sinus tachycardia or supraventricular tachycardia. All of the three entities require medical management. The decrease in heart rate with GTN spray is unusual and it may be just a incidental finding. GTN tends to increase the heart ratw, so next time refrain from taking GTN spray if you feel your heart rate is very fast. You must visit your doctor and get an ECG done. If the ECG does not detect any arrythmia of fast heart rate, then a 24 hour holter monitoring should br done which records the ECG for 24 hrs when the patient is doing his normal day to day activities. This will help detect the rhythm disturbances and treatment can be started accordingly. Since you have history of heart disease a 2 d echo should also be done to rule out organic cause of arrythmia. Take care regards