[Medical Q&A] Why is "sinus rhythm" written on the electrocardiogram report?

Planner: Chinese Medical Association

Reviewer: Chen Bingwei, deputy chief physician, Tianjin First Central Hospital

When you have an electrocardiogram during a physical examination, the doctor will tell you that the electrocardiogram is normal, but the report will say "sinus rhythm." This name sounds like a disease, but in fact, sinus rhythm is a normal heart rhythm.

The heart is a hollow structure similar to a balloon formed by cardiac tissue, including four "chambers" - the left atrium, left ventricle, right atrium, and right ventricle. The heart of a normal human body usually beats regularly, and maintains about 50 to 100 beats per minute when resting. In order for the heart to maintain such regular "work", it needs a sophisticated electrical signal transmission system, and the commander of this system is the "sinoatrial node". The sinoatrial node is located in the upper right corner of the right atrium. It is the natural pacemaker of the heart and can also be regarded as the "headquarters" of the entire heart, managing how many times the heart beats per minute. The electrical signal emitted by the sinoatrial node is quickly transmitted to the atrium, ventricle, and even the entire heart along the entire conduction system. With the electrical signal, the heart can contract and relax regularly. The heart rhythm dominated by the "sinoatrial node" is a normal heart rhythm, referred to as "sinus rhythm". The electrocardiogram is an examination that records the electrical activity of the heart. The report of "sinus rhythm" indicates that the sinoatrial node is the dominant heart rhythm, that is, the normal heart rhythm. If the heart rhythm is no longer dominated by the sinoatrial node but by other abnormal excitation foci, "sinus rhythm" will not be written on the electrocardiogram report, but may be the name of a disease such as "atrial fibrillation", "atrial flutter", or "ventricular tachycardia".