The electrocardiogram of sinus rhythm must meet the following two criteria: (1) P wave is upright in leads I, II, and aVF, and inverted in aVR. (2) P-R interval is 0.12 to 0.20 seconds. There is a unique small nodule on the upper right atrium, composed of unique cells, known as the sinoatrial node.

In normal people, V1, V2 should not be QS waves. Generally, QS waves suggest old myocardial infarction, but if V1, V2 are QS waves without other evidence, it cannot indicate any problems. Electrocardiogram (ECG) examination is actually just an auxiliary examination to determine whether further examination is needed. It is not very correlated with the disease. If you want to determine the exact disease, it is best to do a cardiac ultrasound or other necessary examinations recommended by the doctor to find the cause.

Clinical symptoms

1. Sinus bradycardia usually does not present with symptoms if the heart rate is not less than 50 times per minute.

2. If the heart rate is less than 40 times per minute, it can often cause symptoms such as angina, heart failure, or syncope.

Clinical symptoms of sinus rhythm

Sinus rhythm is common in the general population, presenting in short episodes. When the sinus rate accelerates, it becomes sinus rhythm. Clinical manifestations are similar to those of escape rhythm. Some people feel that it is more common in patients with congenital anomalies of the systemic veins, such as persistent left superior vena cava and inferior vena cava defects.

Treatment criteria

1. Sinus bradycardia does not require treatment if the heart rate is not less than 50 times per minute and there are no symptoms.

2. If the heart rate is less than 40 times per minute and symptoms occur, drugs to increase the heart rate (such as atropine, ephedrine, or isoproterenol) can be used.

3. Patients with marked sinus bradycardia accompanied by sinus arrest and syncope may consider implanting a permanent cardiac pacemaker.

4. Treatment of the original disease.

5. Treatment for the disease and supportive treatment.