most common medical conditions indicated by the symptoms palpitations (fluttering in chest) and pulsating sensation including Atrial fibrillation, Panic attack, and Generalized anxiety disorder. Acute stress reaction symptoms include shortness of breath, anxiety, nervousness, sense of doom and more. Premature ventricular contractions (PVCs) Premature ventricular contractions are extra heartbeats that start in one of the lower chambers of your heart. Heart rhythm disorder Some heart rhythm disorders can cause a fluttering in the chest, shortness of breathing are. Low potassium (hypokalemia) Supraventricular tachycardia. Thyroid storm Vitamin B12 deficiency. Hyperthyroidism Aortic regurgitation other reasons for fluttering sensation Exercise. Your heart beats faster when you exercise; it then gradually slows to normal afterwards. Anxiety. This can be either normal worry, or excessive worry, such as in panic attacks or anxiety disorder. Caffeine. Drinking too much caffeine in coffee, tea, cola or drinks such as Red Bull® may cause your heart to beat faster, giving you palpitations. Alcohol. Certain medication. Some medication such as salbutamol, terbutaline, hyoscine, and hydralazine, amongst others, can cause your heart to beat faster. Some over-the-counter cough and cold medicines can also do this. Other stimulant drugs. Some recreational drugs such as ecstasy, cannabis, cocaine and amfetamines can cause a fast heart rate. An overactive thyroid gland. Smoking. The nicotine in cigarettes can cause a faster heart rate. Having a temperature (fever). you should avoid taking coffee,tea,smoking and avoid anxinty too.