Recently, there are always friends who talk about the diagnosis of sinus arrhythmia in the medical examination report, and when they hear that there is an abnormality in the heart, they are especially nervous and call to consult what is this disease? Is it serious? Does it need to be treated? Why do so many people find sinus arrhythmia in the ECG during medical checkups? Then let’s talk to you in detail about this problem. First, let’s talk about how our heart works. Our heart is a pumping organ, beating rhythmically according to a certain rule, and through diastole and contraction, it shoots blood from the heart into the arteries and delivers it to all organs of the body. And who controls this regular rhythm? Actually, the heart is composed of a complex electrical conduction system whose commander is a structure called the sinus node. Under normal circumstances, the excitation of our healthy heart is sent from the sinus node (the commander), and then the electrical excitation is transmitted through the atria and atrioventricular node to the ventricles in turn, causing the heart to contract and diastole at a fixed frequency, causing the heart to pump blood regularly to meet the needs of the body. The frequency emitted from the sinus node is usually relatively regular, controlled at 60 to 100 beats per minute. Clinically, we call this heart rhythm from the sinus node sinus rhythm, sinus rhythm is the normal heart rhythm, so normal healthy people are sinus rhythm. Second, what is sinus arrhythmia? Sinus arrhythmia is a condition in which the rhythm is still controlled by the sinus node, but the rhythm is irregular, which is clinically shown by the difference of P-P interval >0.12s in the same lead when checking the ECG, and sinus arrhythmia is often accompanied by sinus bradycardia (heart rate <60 beats/min). C. Is this arrhythmia serious? Does it require treatment? Sinus arrhythmia is a normal physiological phenomenon, not a disease. Sinus arrhythmias are most common in children and young adults, but can also be seen in healthy adults. Sinus arrhythmias are usually asymptomatic, but if the intervals are long, you may experience panic. Sinus arrhythmias themselves are usually unnecessary to treat and disappear with increased heart rate after activity. One of the more common types of sinus arrhythmias is related to the whistling cycle, called whistling sinus arrhythmia, the mechanism is due to changes in the tension of the vagus and sympathetic nerves in the body during the whistling process, so that the sinus node autoregulation also undergoes periodic, regular changes. During inspiration, sympathetic tone increases and the heart rate increases, while during expiration, vagal tone increases and the heart rate slows. It is usually seen in adolescents and is generally not clinically significant. In addition, factors such as mental stress may also cause "sinus arrhythmia", but this condition does not require treatment.