Thank you for your query. An ECG is a study of the electric impulses and their conduction through the heart muscle. The sinus node is the starting point of that impulse and it generates these signals with a preset rhythm. This is then conducted through the rest of the heart by nerve bundles. The heart is made of 4 chambers - 2 upper (atrium) & 2 lower (ventricles). All conducting tissues of the heart can initiate this impulse but the sinus is the predominant one and takes over. The sinus impulse first initiates the atria to contract, pushing all the blood into the ventricles. The signal then moves to the ventricles which then cause it to contract and push the blood out of the ventricles into the body/lungs (left/right ventricle respectively). The heart relaxes briefly before doing this all over. A premature supra ventricular beat occurs when there is an impulse generated by another point of the heart (in the atria or at the junction between atria and ventricle) that causes the heart to contract in a different way and interferes with the normal filling and ejection of blood. The heart can usually recover from this quickly and get back on track (if the number of premature beats are less (2-4) per minute. However, if too many occur, the circulation gets compromised. A premature beat occurs due to damage of the heart muscle, electrolyte imbalances, certain medications. Your ECG anterior infarction of an unknown age. Did you have any heart disease or attacks? I recommend you to see your physician to rule out and treat the correctable causative factors (if you have it). In the meantime, any chest pain, giddiness, unexplained sweating, new digestive problems, palpitations (feeling of heart racing or thumping) that you may experience needs immediate attention and a emergency consult. Hope this help. Please let us know if you have any other questions. Wish you good health