What Is Sinus Tachycardia?

Sinus tachycardia is called in adults when the frequency controlled by the sinoatrial node exceeds 100 beats per minute. This is the most common type of tachycardia, and its occurrence is often related to sympathetic nerve excitation and reduced vagal tone. It is not a primary arrhythmia and can be caused by a variety of causes. Under physiological conditions, it can be caused by exercise, anxiety, and emotional excitement, and it can also occur after the application of drugs such as epinephrine and isoprenaline. It is extremely easy to occur in fever, hypovolemia, anemia, hyperthyroidism, respiratory insufficiency, hypoxemia, hypokalemia, heart failure and other heart diseases. The disease can be cured after controlling the primary lesion or inducing factors, but it is easy to relapse.

Basic Information

English name: sinus tachycardia
Visiting department: Cardiology

Common causes: Exercise, anxiety, emotional agitation and certain diseases can cause
Common symptoms: Palpitations, sweating, dizziness, fatigue, or primary symptoms

Causes of sinus tachycardia

Physiological factor

Many factors affect heart rate, such as normal physical activity, emotional excitement, full meals, drinking strong tea, coffee; smoking, drinking, etc. can excite the sympathetic nerves and speed up the heartbeat. Postural changes, such as sympathetic nerve excitement in the upright position, also increase the heart rate; in the supine position, the heart rate decreases. Sinus tachycardia caused by physiological factors is often transient and of short duration.

2. Pathological factors

(1) Heart failure: Especially in the early stages of heart failure, heart rate often increases.

(2) Hyperthyroidism: Most patients with hyperthyroidism have sinus tachycardia. The heart rate is generally 100 to 120 beats per minute. In severe cases, the heart rate can reach 120 to 140 beats per minute.

(3) Acute myocardial infarction In the course of acute myocardial infarction, the incidence of sinus tachycardia can reach 30% to 40%.

(4) Shock can cause sinus tachycardia, the heart rate can reach more than 100 times / minute in mild shock; the heart rate is faster in severe shock, which can be greater than 120 times / minute.

(5) Most patients with acute myocarditis may have sinus tachycardia that is disproportionate to an increase in body temperature.

(6) Sinus tachycardia can occur in other organic heart disease .

(7) Sinus tachycardia can occur in other patients with anemia, fever, infection, hypoxia, autonomic dysfunction, and after cardiac surgery.

(8) Drugs such as epinephrine and atropine can also cause sinus tachycardia.

Clinical manifestations of sinus tachycardia

1. Palpitations, or sweating, dizziness, dizziness, fatigue, or manifestations of primary disease.

2. Can induce other arrhythmias or angina.

3. The heart rate is mostly 100 / minutes to 150 times / minute, most of them have strong heart sounds or have signs of primary heart disease.

Sinus tachycardia

1. Characteristics of ECG

(1) P wave: P wave in sinus tachycardia is emitted by the sinoatrial node, PII is upright, PavR is inverted. P wave in sinus tachycardia is slightly higher in amplitude than P wave in normal sinus rhythm. It is more obvious in lead -. This is because when sinus tachycardia occurs, the excitement mostly occurs in the head of the sinoatrial node, which is the starting point of the anterior internode node bundle.

(2) The PR interval is between 0.12 and 0.20 seconds.

(3) The interstitial period of PP is often affected by autonomic nerves and may be slightly irregular, but the difference between PPs should be.

(4) QRS wave morphology, time limit is normal, atrial rate and ventricular rate are equal.

(5) Frequency: Adult P-wave frequency is 100-160 times / minute, most of which are about 130 times / minute, and some can reach 160-180 / minute. The heart rate of infants and young children is slightly higher than that of adults. The diagnostic criteria for sinus tachycardia are different at different ages. For example, it should be> 140 beats per minute within 1 year, and> 120 beats per minute between 1 and 6 years. It should be more than 100 times / minute, usually not more than 160 times / minute. The frequency of sinus tachycardia in individual infants can reach about 230 beats per minute.

Characteristics of 2.24h ambulatory ECG monitoring

(1) The frequency of sinus P waves in transient sinus tachycardia gradually increases to more than 100 times per minute for several seconds to minutes, and then gradually slows down to the original level. The morphology of P waves during normal tachycardia is normal sinus. The shape of the P wave is the same.

(2) The total number of P waves recorded by continuous sinus tachycardia in a 24-h dynamic electrocardiogram should be> 144,000.

(3) Other concomitant conditions recorded by the 24h dynamic electrocardiogram during sinus tachycardia The P wave amplitude became sharper or higher, suggesting that the excitement originated in the head of the sinoatrial node. P-R segment downward movement is caused by atrial repolarization. There may be different degrees of secondary ST-T changes or original ST-T changes, and it returns to normal when sinus tachycardia occurs. Q-T interval shortened. Arrhythmia such as contraction before fast heart rate dependent block.

Sinus tachycardia diagnosis

A diagnosis can be made based on clinical manifestations and an electrocardiogram. This disease needs to be distinguished from atrial paroxysmal tachycardia, which is mainly determined by electrocardiogram.

Sinus tachycardia treatment

Treatment principle

(1) Eliminate incentives and treat primary disease.

(2) Treat symptomatically.

2. Principles of medication

(1) The treatment of sinus tachycardia should mainly treat the primary disease, supplemented with symptomatic treatment if necessary. Sinus tachycardia caused by congestive heart failure, digitalis preparations, diuretics and vasodilators are applied. Correction of sinus tachycardia is often used as one of the indicators of left heart failure control.

(2) For the treatment of sinus tachycardia caused by non-heart failure, -blockers and sedatives can be selected.

(3) In the treatment of patients with acute myocardial infarction, when there is no clear cardiac insufficiency, and sinus heart rate continues> 110 times / minute, in order to slow down the heart rate, a small dose of -blocker such as oral altibra Lol or calcium antagonists, such as oral thiazezone, can be taken once every 8 to 12 hours. Sinus tachycardia secondary to left heart failure should primarily address heart failure.