What is Premature Ectopic Beat and Supraventricular Ectopic Beat?

Ectopic heartbeat is associated with the abnormal electrical conduction or activity of the heart. It is a light variation in the heart beat and causes irregular pulse. The patient feels a thump or a flutter in the chest as if the heart missed a beat. 

Premature ectopic beat is the most common type of arrhythmia which is most often harmless. The premature ectopic beat can be of atrial origin or of ventricular origin. 
Supraventricular ectopic beat originates either from the atria or from the atrioventricular node which is called as the junctional premature beat. It may indicate an atrial dilation and shows premature and narrow QRS complex on the ECG. 
Very often the symptoms are aggravated due to stress or factors like alcohol, caffeine, exercise emotions etc. It can last for as long as a few days and sometimes lasts just for a few minutes.  
Clinically the blood pressure is found low. This occurs due to the lesser pumping effect of the heart which results in a lower cardiac output. Pounding of the heart can be as much as 150 to even 250 per minute. 
Some of the symptoms of supraventricular ectopic beat are rapid breathing, shortness of breath, rapid beating of heart and sometimes chest pain with dizziness. Numbness in extremities is also common.