Hello, 
welcome to Healthcare Magic. 
Heart flutter can be experienced due to 
palpitation or due to to muscular twitches over chest. Palpitations are common and normal during exertion like playing tennis. 
If it is occurring during resting state, then there is need to rule out following conditions:
-Anxiety disorders: can manifest not only with psychological symptoms but with a variety of physical symptoms also like: 
Tingling, numbness, palpitation, chest heaviness, tremors (shakiness) etc. It is better to get evaluated by 
psychiatrist and start treatment accordingly.
-Cardiac illness: Like 
arrhythmia. Consultation with cardiologist will be helpful.
Same time do some relaxation exercise like yoga and 
breathing exercise, which will help you in recovery from current symptom. 
Wish you good health and all the best. 
Regards, 
Dr Ashish Kumar Mittal 
www.99doctor.com