Patients with viral myocarditis often feel “a sudden pause in the heart” or “a sudden, violent pounding of the heart against the chest”, or even “the heart suddenly jumping into the throat”. What is the reason for this? It turns out that this is a premature heartbeat. We know that a normal human heart contraction is rhythmic, and there is an interval between contractions. If a person’s heart beats 80 times a minute, then there is a 0.75 second interval between contractions. The sinus node generally governs the rhythm of the heart, but the atria or ventricles can also generate their own excitation to cause the heart to contract. If the atria or ventricles send an excitation prematurely on their own during the short interval after the contraction due to neurological or humoral factors and pathological damage such as myocarditis, the heart contracts prematurely before the next excitation from the sinoatrial node, which is called “preterm contraction” or This is called “preterm contraction” or “premature beat”, which we all like to call premature beat for short. When you are concentrating on your work, a sudden sound may startle you, or when you are just falling asleep, a sudden “re-beat” from your heart may wake you up from your sleep. However, the perception of premature beats varies according to the sensitivity of the person. Some people do not feel anything despite having many beats per minute, while others experience the above mentioned discomfort with every beat. The reason why premature beats can cause these symptoms is also simple. When the heart is beating systematically, people are used to it and usually do not feel it “beating”. However, if the heart beats early, and there is a long interval after this early beat, people may feel that the heart is beating unevenly, and some may even feel that the heart has stopped beating once. In addition. When the heart is in rhythm, the amount of blood expelled by the heart is the same for each contraction. However, when a premature beat occurs, because the heart is not fully “filled” with blood, the amount of blood discharged during contraction is less, while the next contraction is after a longer interval, when the heart is filled with more blood, the amount of blood discharged during contraction is also more, the heart contraction must be stronger, and more sensitive people will have abnormal feelings such as heart pounding. The more sensitive people may experience abnormal sensations such as heart pounding. If premature beats occur once in a while in normal heart rhythm, they are called episodic premature beats; if they occur once every second normal beat, they are called duplex and triplex rhythm. There are many different types of premature beats when observed with the help of electrocardiogram. There are atrial premature beats, atrioventricular junctional and ventricular premature beats. Ventricular premature beats are the most frequent, accounting for 70%, atrial premature beats are the second most frequent, accounting for 20%, and about 10% are atrioventricular junctional premature beats.