There are obvious differences between sinus rhythm and sinus arrhythmia, as follows: First, sinus rhythm means that the heart rate sends out impulses at the normal pacing point, which is in the sinus node, while sinus arrhythmia means that the origin of the heart rhythm is unchanged, and the same impulses and origins are sent out in the sinus node, but the rhythm and frequency are significantly changed. 2. In sinus arrhythmia, the patient will have typical clinical symptoms and reactions, in Patients do not have obvious symptoms during sinus rhythm, such as palpitations, dizziness, and weakness during arrhythmias. Early symptoms are usually not obvious, but in case of significant sinus arrhythmia, patients will experience significant dizziness, palpitations, precordial discomfort, chest tightness and shortness of breath, and even transient blackness and sudden collapse, all of which are clinical symptoms of severe sinus arrhythmia.