OVERVIEW

What is sinus arrhythmia?

To understand what sinus arrhythmia means, it's necessary to first introduce sinus rhythm. Under normal circumstances, the sinoatrial node of the heart generates impulses that travel through the heart's conduction system, controlling the regular contraction and relaxation of the entire heart. This normal heart rhythm is referred to as "sinus rhythm."

In healthy adolescents and adults at rest, the sinus rhythm ranges between 60–100 beats per minute, while infants and children have a faster heart rate than adults.

Sinus rhythm is influenced by various factors, including posture, emotions, physical activity, body temperature, metabolism, medications, and heart conditions, all of which can affect its frequency.

In simple terms, sinus arrhythmia refers to an irregular heartbeat. On an electrocardiogram (ECG), it appears as a significant variation in the sinus rhythm's speed, with differences between adjacent cardiac cycles exceeding 120 ms (equivalent to 3 small squares on the ECG).

Which department should you visit for sinus arrhythmia?

Cardiology or general internal medicine.

SYMPTOMS

What are the manifestations of sinus arrhythmia?

Sinus arrhythmia usually has no obvious symptoms.

Simple sinus arrhythmia generally does not cause a significant reduction in cardiac output. Therefore, compared with ventricular arrhythmia, sinus arrhythmia does not present symptoms of reduced cardiac output, such as dizziness, blackouts (sudden vision loss or blurred vision), chest tightness, etc.

If sinus arrhythmia is caused by an underlying disease, symptoms related to the primary condition may appear. For example, myocardial ischemia may manifest as chest tightness or chest pain, and occasional palpitations may occur when the heart rhythm is noticeably irregular.

CAUSES

What are the classifications of sinus arrhythmia?

It can generally be categorized into the following types based on etiology:

• Respiratory sinus arrhythmia: The heart rate increases during inhalation and decreases during exhalation, with the irregularity disappearing when breathing is paused. It is commonly seen in healthy children.

• Non-respiratory sinus arrhythmia: Changes in heart rate are unrelated to breathing and are more frequently observed in patients with heart disease or those taking digitalis medications.

• Ventriculophasic sinus arrhythmia: Primarily seen in patients with high-grade or complete atrioventricular block. The PP intervals containing ventricular beats are shorter than those without ventricular beats.

Is sinus arrhythmia hereditary?

The vast majority of sinus arrhythmias are not hereditary.

A very small number of diseases causing sinus arrhythmia may be inherited, such as sick sinus syndrome. In its early stages, sinus arrhythmia may occur without any apparent cause. At the genetic level, it mainly manifests as mutations in the cardiac sodium channel genes SCN5A and HCN4, which may be passed down within families.

DIAGNOSIS

What tests and examinations are needed for sinus arrhythmia?

If sinus arrhythmia is not accompanied by obvious symptoms, it generally does not require a hospital visit.

If accompanied by discomfort such as chest tightness, chest pain, palpitations, or dizziness, doctors usually recommend the following routine examinations to rule out cardiac or non-cardiac diseases:

• Electrocardiography (ECG): ECG is the preferred test for diagnosing sinus arrhythmia. A surface ECG can detect abnormalities in the heart's electrical activity, such as ectopic beats, ST-segment elevation or depression, T-wave flattening or inversion, or the presence of U waves.

• Dynamic Electrocardiography (DCG): A standard ECG records the heart's electrical activity over a short period (usually 15 seconds to a few minutes), while a DCG can record it for 24 hours or longer. This test helps detect paroxysmal arrhythmias.

• Ultrasonic Cardiogram (UCG): This examination assesses the heart's anatomical structure for abnormalities, such as valve insufficiency or stenosis, abnormal myocardial activity, or extracardiac issues like pericardial effusion or pericardial masses.

• Creatine Kinase-MB (CK-MB) and Troponin (TnI): These tests evaluate whether myocardial cells are damaged. Elevated levels may indicate that the arrhythmia is caused by myocardial necrosis.

TREATMENT

How to treat sinus arrhythmia?

Sinus arrhythmia itself does not require treatment, as healthy individuals may also experience it without any discomfort.

Treatment is only necessary when sinus arrhythmia is a secondary symptom of a disease, referred to by doctors as "pathological sinus arrhythmia." In such cases, the underlying disease should be treated. Once that disease is cured, sinus arrhythmia will naturally improve. This condition can be cured and generally does not leave any sequelae.

Common pathological factors that may cause sinus arrhythmia include certain heart diseases, the use of digitalis medications, and high-degree or complete atrioventricular block.

Can sinus arrhythmia resolve on its own?

Simple sinus arrhythmia has a good prognosis.

Respiratory sinus arrhythmia in children and adolescents may disappear as they grow older.

DIET & LIFESTYLE

What should people with sinus arrhythmia pay attention to in daily life?

If sinus arrhythmia causes noticeable discomfort such as palpitations, dizziness, or nervousness, seek medical attention promptly.

If sinus arrhythmia does not cause significant symptoms and there are no other underlying health conditions, normal daily activities and exercise are permitted without restrictions.

What dietary precautions should people with sinus arrhythmia take?

• Minimize the consumption of strong tea and coffee;

• Quit smoking and alcohol;

• Maintain a balanced diet.

PREVENTION

How to prevent sinus arrhythmia?

In daily life, try to avoid factors that may cause sinus arrhythmia, such as:

• Strong tea, coffee, tobacco, and alcohol;

• Methylxanthine drugs.