sinus tachycardia
Introduction
Introduction to sinus tachycardia Sinus tachycardia (sinustachycardia) refers to the rate of adult sinus node impulse formation more than 100 times per minute, the rate is often between 101-160 times per minute. When sinus tachycardia begins and ends, its heart rate gradually increases and slows down. Sinus tachycardia is a common arrhythmia. basic knowledge Sickness ratio: 0.2%-0.5% Susceptible people: no specific people Mode of infection: non-infectious Complications: cardiogenic shock heart failure
Cause
Cause of sinus tachycardia
(1) Causes of the disease
1. Physiological factors Physical activity of normal people, emotional excitement, full meal, drinking strong tea, drinking coffee, smoking, drinking, etc., make the sympathetic nerves excited, and the heart rate is accelerated.
2. Pathological factors
(1) Heart failure: especially in the early stages of heart failure, the heart rate often increases.
(2) Hyperthyroidism: Most hyperthyroidism patients have sinus tachycardia, heart rate is generally 100 ~ 120 times / min, severe heart rate can reach 120 ~ 140 times / min.
(3) Acute myocardial infarction: In the course of acute myocardial infarction, the incidence of sinus tachycardia can reach 30% to 40%.
(4) shock: shock can cause sinus tachycardia, heart rate can reach 100 beats / min or more in mild shock; heart rate is faster in severe shock, can be greater than 120 beats / min.
(5) Acute myocarditis: Most patients may have sinus tachycardia that is not proportional to the increase in body temperature.
(6) Other organic heart disease: sinus tachycardia can occur.
(7) Anemia, fever, infection, hypoxia, autonomic dysfunction, sinus tachycardia can occur after cardiac surgery.
(8) drugs: such as adrenaline, atropine can also cause sinus tachycardia.
(two) pathogenesis
The occurrence of sinus tachycardia is mainly related to sympathetic excitation and vagal tone reduction. When sympathetic excitation affects sinus node pacemaker cells, the 4-phase ascending velocity is accelerated, the time to reach the threshold potential is shortened, and the heart rate is accelerated.
1. Physiological factors Physiological sinus tachycardia is an "adaptation" phenomenon, which affects many factors such as normal human activity, emotional agitation, full meal, drinking tea, coffee; smoking, drinking, etc. can make sympathetic nerves Excitement, rapid heartbeat, body position changes such as sympathetic excitation, heart rate is also accelerated; heart rate is slowed when lying, physiological factors caused by sinus tachycardia is often transient, short duration.
2. Pathological factors
(1) Heart failure: In heart failure, heart rate tends to increase, which is one of the compensatory mechanisms for the body to maintain cardiac output. Heart rate in patients with heart failure is compensated within a certain range.
(2) Hyperthyroidism: Most patients with hyperthyroidism have sinus tachycardia.
(3) Acute myocardial infarction: The incidence of sinus tachycardia is higher in the course of acute myocardial infarction. This is due to the systemic stress response, increased catecholamine secretion, pain, tension, and insufficient blood volume in the early stage of the disease. Or concurrent infection, fever and other factors, such as persistent sinus tachycardia is a large infarct size, decreased cardiac output, left heart failure or necrosis, poor myocardial healing and repair.
(4) Shock: The degree of sinus tachycardia is often used as one of the indicators of the severity of shock.
(5) Acute myocarditis: Sinus tachycardia occurs in this disease, which is caused by impaired cardiac function due to acute inflammation of the myocardium.
(6) anemia, fever, infection, hypoxia, autonomic dysfunction, after cardiac surgery: can cause sinus tachycardia, every 1 °C increase in body temperature, heart rate can be increased by 12 to 15 times per minute, in addition, The application of sympathomimetic drugs, such as epinephrine, ephedrine and other sympathetic nerve stimulation, or the use of vagus nerve block drugs (such as atropine), relieved the vagus nerve inhibition of the heart, can also occur transient sinus tachycardia.
Prevention
Sinus tachycardia prevention
Sinus tachycardia is not a separate disease. In the case of the disease, we should first try to avoid the incentives, such as drinking strong tea, drinking alcohol and applying drugs that stimulate the heart to speed up the heart rate, keep the mood happy, prevent excessive excitement and anxiety, and have regular living. Suitable diet, do not overwork; appropriate physical exercise to prevent colds.
Complication
Sinus tachycardia complications Complications cardiogenic shock heart failure
Symptom
Symptoms of sinus tachycardia common symptoms shortness of breath chest pain chest tightness heart palpitations hemodynamic disorder heart rate increase tachycardia transient consciousness
There are no special symptoms of this disease, which are often caused by other diseases. The clinical symptoms are related to the degree of hemodynamic disorder caused by the increased heart rate. It is also related to the basic heart state. When the heart rate is slightly increased, the heart is bleeding. The amount increases, the heart work efficiency increases, the patient can have no symptoms. When the heart rate is too fast, the patient may have symptoms such as palpitations, shortness of breath, chest tightness, irritability, and even chest pain. The individual differences of symptoms are also large, usually from rest. In the state, the heart rate increases to about 2.5 times (180 times/min), and the heart works most efficiently. When it exceeds 180 times/min, the heart work efficiency is significantly reduced, which cannot meet the needs of the body. When the heart rate is >180 beats/min, the myocardial oxygen consumption is significantly increased, the coronary blood flow is reduced (more obvious in patients with coronary heart disease), the end-diastolic period is shortened, the ventricular filling is reduced, and the cardiac output is reduced.
Signs: heart rate increased to 100 ~ 150 times / min, a few people can reach 160 ~ 180 times / min, most of the physiological are transient; those caused by structural heart disease, the tachycardia lasts longer The apex is powerful, the heart sound is enhanced, and the carotid artery beats obviously.
Diagnosis can only rely on ECG examination. The characteristics of ECG are:
1. P wave has a regular P-wave morphology at the onset of tachycardia and the P-wave morphology of the normal sinus rhythm. The time limit and amplitude are exactly the same.
2. The P wave frequency is greater than 100 times/min, and is mostly around 130 times/min.
3. The PR interval is greater than 0.12 s.
4. During the beginning of pp sinus tachycardia, the sinus tachycardia can be gradually shortened, and gradually slow down to the original time limit at the time of termination. The PP spacing is shorter than 0.6 seconds when the sinus tachycardia is short, and the longest and shortest is the sinus arrhythmia. The difference in PP pitch is more than 0.12 seconds.
5. There are reasons for tachycardia.
Examine
Sinus tachycardia
The examination of this disease mainly depends on the electrocardiogram
1. Surface ECG features
(1) P wave: P wave in sinus tachycardia is emitted by sinus node, PII is upright, PavR is inverted, and P wave in sinus tachycardia is slightly higher than normal P sinus rhythm. In the II and III leads, it is more obvious. Because of sinus tachycardia, the stimuli occur mostly in the head of the sinus node. This part is the starting part of the anterior interphalangeal plexus. The result is that the knot is passed down.
(2) PR interval: between 0.12 and 0.20 s.
(3) PP interval: often affected by autonomic nerves, may have mild irregularities, but the difference between PP periods should be
(4) QRS wave: morphology, time limit is normal, atrial rate is equal to ventricular rate.
(5) Frequency: Adult P wave frequency is 100-160 beats/min, mostly at 130 beats/min, and individual can reach 160-180/min. The heart rate of infants and young children is slightly higher than that of adults. Different ages of sinus tachycardia Diagnostic criteria are different, such as >140 times/min within 1 year old, >120 times/min for 1 to 6 years old, the same as adults for 6 years old and above, should be greater than 100 times/min, usually not more than 160 times/min, individual infants The frequency of sinus tachycardia in young children can reach about 230 times/min.
2. Characteristics of sinus tachycardia 24h dynamic electrocardiogram monitoring
(1) The sinus P wave frequency of transient sinus tachycardia: gradually increased to more than 100 beats/min, gradually slowed down to the original level after several seconds to several minutes, and the P wave shape and normal during tachycardia The sinus P wave has the same morphology.
(2) The total number of P waves recorded in the continuous sinus tachycardia 24h dynamic electrocardiogram should be >144,000 times.
(3) Other concomitant conditions recorded by the 24h dynamic electrocardiogram during sinus tachycardia:
The amplitude of the 1P wave is sharpened or increased: the stimulating originates from the sinus node head.
2P-R segment down: This is caused by the influence of atrial repolarization.
3 There may be different degrees of secondary ST-T changes: or the original ST-T changes, return to normal when sinus tachycardia occurs.
The 4Q-T interval is shortened.
5 rapid heart rate-dependent block, pre-systolic and other arrhythmias.
Diagnosis
Diagnosis and diagnosis of sinus tachycardia
Differential diagnosis
1. Paroxysmal atrial tachycardia and sinus tachycardia overlap in the P wave frequency, so it is easy to cause difficulty in the identification of the two, the identification mainly depends on the ECG, the following points can help identify:
(1) The P' wave of paroxysmal atrial tachycardia is different from the sinus P wave.
(2) The P' wave frequency of paroxysmal atrial tachycardia is mostly 100-180 beats/min, mostly at 160 beats/min, while the P-wave frequency of sinus tachycardia is more than 140 beats/min. , rarely more than 150 times / min, and susceptible to sports, standing, eating, emotional, bed rest, rest, breathing (deep inhalation to increase heart rate, deep exhale can slow heart rate) and other factors, and Atrial tachycardia is not affected by the above factors.
(3) The occurrence of paroxysmal atrial tachycardia is a sudden onset, abrupt termination, and there is a compensatory interval at the termination, while sinus tachycardia is gradually occurring, and gradually terminates, and there is no compensatory interval at the termination.
(4) Absolute regularity of PP interval during paroxysmal atrial tachycardia, while sinus tachycardia often has mild irregularities in PP interval.
(5) Atrial tachycardia often occurs before and after paroxysmal atrial tachycardia, while sinus tachycardia has no atrial contraction.
(6) The method of stimulating the vagus nerve by oppression of the eyeball or carotid sinus, the atrial tachycardia can not be terminated but can induce atrioventricular block; while the reentry tachycardia can be terminated or induced Ventricular conduction block, the frequency of sinus tachycardia can be gradually slowed down by the above method, it is impossible to be suddenly terminated; and when the oppression is stopped, it can be restored to the original faster level.
2. ST-T changes in sinus tachycardia and ST-T changes in coronary heart disease. Sinus tachycardia can show ST segment depression, T wave flat or inverted, TP segment during sinus tachycardia Shorten, so that the P wave overlaps with the T wave before it. At this time, the TP segment cannot be used as the equipotential line to determine whether the ST is lowered. When the sinus tachycardia is high, the P-wave is re-polarized due to PII and III. (Ta) is also more obvious, and the posterior segment can be extended to the ST segment, causing the ST segment to decrease, mainly in the II and III leads. When the sinus tachycardia occurs in patients with coronary heart disease, it can cause relative blood supply to the coronary artery. Insufficient, leading to ST segment reduction and T wave changes, in some patients after ST-T changes after sinus tachycardia often take some time to return to normal, so in sinus tachycardia can not be based solely on ST-T changes To diagnose coronary heart disease, it must be considered comprehensively in combination with clinical conditions.
