Premature beats are caused by excessive humoral regulation in a certain part of the heart. If a premature beat is caused by excessive humoral regulation in a place inside the ventricle, it is called an atrial premature beat; if a premature beat is caused by a high peak point in the atrioventricular node or the atrium, it is called an atrioventricular node or ventricular premature beat. The main differences between atrial and ventricular premature beats are as follows:

1. The first heart sound of ventricular premature beats is stronger than that of atrial premature beats.

Because when ventricular premature beats occur, the ventricle has already been ejecting blood into the atrium, and the atrioventricular valve is still fully open. Therefore, the sound (first heart sound) caused by the sudden closure at this time is naturally very loud. However, atrial premature beats do not have this feature.

2. Ventricular premature beats can cause the first heart sound to be destroyed, while atrial premature beats cannot.

Because when ventricular premature beats occur, the pacing sequence of this excitement is not generated in accordance with the normal sequence, which will lead to the contraction of the left and right ventricles being out of step, and the atrioventricular valves of the left and right atria will not close simultaneously. (Normal excitement starts from the top of the septum and is basically transmitted to the upper and lower atria, so the upper and lower atria also basically contract simultaneously, and the upper and lower atrioventricular valves also basically close, resulting in the first heart sound not being destroyed)

3. The interval after ventricular premature beats is longer than that after atrial premature beats.

This is because the refractory period of ventricular premature beats is complete, while that of atrial premature beats is incomplete.

4. Ventricular premature beats can be accompanied by positive jugular venous beats.

Due to the ventricular premature beat, the ventricle has already been ejecting blood into the atrium, and the atrioventricular valve is still fully open. Therefore, when the right ventricle suddenly contracts at this time, it may cause the blood in the right ventricle to reflux into the right atrium, and then flow back into the jugular vein, thereby causing a jugular venous heartbeat.