Chronic spontaneous atrial tachycardia

Introduction to chronic autonomic atrial tachycardia Chronic autonomic atrial tachycardia, also known as chronic atrial tachycardia, persistent atrial tachycardia or endless atrial tachycardia, is a special type of tachycardia. According to this type of tachycardia with or without intermittent sinus beats, it can be divided into two subtypes: 1 chronic persistent (long) atrial tachycardia, 2 chronic recurrent atrial tachycardia. The cause of this disease is not clear. Primary chronic autonomic atrial tachycardia is more common in infants and young children, often caused by congenital, hereditary or anatomical factors; patients with secondary chronic autonomous atrial tachycardia often have a clear endless cardiac motility The reason for overspeed. basic knowledge The proportion of illness: 0.001% Susceptible population: primary chronic autonomic atrial tachycardia is more common in infants and young children Mode of infection: non-infectious Complications: arrhythmia cardiomyopathy congestive heart failure

Chronic autonomic atrial tachycardia

(1) Causes of the disease

The etiology is still unclear. Primary chronic autonomic atrial tachycardia is more common in infants and young children. It is often caused by congenital, hereditary or anatomical factors. Patients with secondary chronic autonomic atrial tachycardia often have clear Causes of endless tachycardia, common in congenital or acquired acquired heart disease, myocarditis, pericarditis, etc. or by drugs, scarring of cardiac surgery (also known as incisional endless tachycardia), radiofrequency ablation Caused by injury.

(two) pathogenesis

Chronic atrial tachycardia is caused by increased self-discipline of ectopic rhythm in the room. It is a type of atrial tachycardia. Chronic atrial tachycardia can also occur due to the mechanism of intraventricular reentry. Rare.

1. Reentry mechanism Electrophysiological studies suggest that chronic atrial tachycardia is caused by the mechanism of intraventricular reentry. When the sinus cardiac cycle is progressively shortened to a critical value, the refractory period of the conduction channel is relatively extended. , so that a certain sinus heartbeat falls in the relative refractory period of the previous heartbeat, resulting in three phases of complex incompleteness and conduction block, that is, three-phase conduction block, including one-way block and conduction slowdown, When impulsive conduction slows down to return to the proximal common channel through the anterior block, the extent to which the zone has recovered from the refractory period, ie, the degree of criticality (the degree of restorative recovery of myocardial cell membrane potential at some point) The circulation pathway is formed. Since the forward conduction block is also a conduction slowdown zone, when the sinus cycle is progressively shortened to a critical degree, a chronic iteration of the sinus rhythm with constant PR interval occurs. Sexual tachycardia.

Due to the progressive shortening of the sinus cycle, it can be achieved through mental stress, emotional arousal, sudden change of body position, significant sinus arrhythmia, fever or physical activity, which explains the room rate of the disease and Atrioventricular conduction is extremely variable. In the change of position, emotion, pain or activity, the atrioventricular block can be relieved and the ventricular rate suddenly increases. This is the recurrent characteristics of chronic atrial tachycardia.

2. Self-discipline increase mechanism At present, most scholars believe that chronic atrial tachycardia is caused by increased self-discipline of ectopic pacemakers in the room and belongs to a type of autonomous atrial tachycardia.

Chronic autonomic atrial tachycardia prevention

1. Patients with chronic atrial tachycardia without structural heart disease have a good prognosis, rarely have heart failure and cerebrovascular complications, many patients can withstand surgery, pregnancy, but the prognosis of organic heart disease is poor, should Actively treat the primary disease.

2. Can eliminate various incentives, such as nervousness, emotional excitement, smoking, drinking, excessive fatigue, anxiety, indigestion, etc., should avoid excessive consumption of coffee or tea, etc., if necessary, can take appropriate amount of sedatives.

Chronic autonomic atrial tachycardia complications Complications arrhythmia cardiomyopathy congestive heart failure

Can be complicated by arrhythmogenic cardiomyopathy, chronic congestive heart failure and other complications.

Chronic autonomic atrial tachycardia symptoms common symptoms systolic murmur tachycardia shortness palpitations palpitation arrhythmia edema heart failure heart enlargement heart rate faster

1. The age of onset is mostly children, adolescents or young people. Some patients have tachycardia at birth, and those who are over 55 years old are rarely seen.

2. The type of tachycardia is different in heart rate. Even if the same patient has a different heart rate at different times, the heart rate is significantly affected by autonomic nerves. The heart rate is 150-180 beats/min, and the reported heart rate is 100-150 beats/min. , rarely more than 200 times / min.

3. Clinical symptoms Although tachycardia persists for a long time, except for mild palpitations and chest tightness, most of them have no serious symptoms. However, if the patient's heart rate increases for a long time, the heart contraction function may decrease, and dilated cardiomyopathy and congestiveness may form. Heart failure, many patients first seen after the occurrence of heart failure, heart failure more common in patients with ventricular rate of more than 180 beats / min, can also be seen in repeated patients, it has been reported that about half of pediatric patients have vomiting, abdominal pain and other symptoms, The reason is not clear.

4. The course of tachycardia The patient's atrial tachycardia persists in many years of follow-up, and there are many people who have been in the past 10 years. It is generally believed that it should last for at least several months or even years. There is a group of reports that 10 cases persist for more than 4 months. The course of infants and young children is often progressively worse, and treatment is more difficult.

5. Endless tachycardia and arrhythmogenic cardiomyopathy animal experiments show that after 3 to 5 weeks of continuous rapid atrial stimulation, the heart can significantly increase the formation of dilated cardiomyopathy, and then develop into heart failure.

The diagnostic criteria for arrhythmogenic cardiomyopathy caused by endless tachycardia are: 1 complaints of cardiac dysfunction such as palpitation, shortness of breath, lower extremity edema, heart rate increase, heart enlargement, apical systolic murmur and other heart failure Signs. 2 There is a long history of episodes of endless tachycardia and data. 3 ECG can be seen in the onset of endless tachycardia, echocardiography can be found that the heart is enlarged, the ventricular wall is thin, and the systolic function is diminished. 4 can rule out heart failure and tachyarrhythmia caused by coronary heart disease, hypertensive heart disease, congenital heart disease or other organic heart disease. 5 Heart failure is significantly improved after rapid arrhythmia control, and myocardial disease can be partially reversed.

Chronic autonomic atrial tachycardia

Mainly rely on ECG diagnosis, ECG features are:

1. ECG characteristics of chronic persistent autonomic atrial tachycardia

(1) The atrial frequency is often slower than paroxysmal atrial tachycardia: generally 150-180 beats/min, but also 100-150 beats/min, rarely exceeding 200 beats/min.

(2) The ectopic P' wave is easily identifiable in the standard lead: even if the atrial rate is fast, the average frontal electric axis of the P' wave is +110° to -90°, and most of them are less than 0°, P' The wave is mostly inverted in the II, III, and aVF leads, and can also stand upright.

(3) The atrial rate changes greatly: the atrial rate can be more than 50 times/min when awake and sleep, and the dynamic electrocardiogram can be different by 80 times/min within 24 hours, which is related to the influence of autonomic function, body position, breathing, Factors such as swallowing, vagus nerve stimulation, activity, painful stimuli, and emotional agitation are sensitive. These factors can significantly change the atrial rate, and there is a tendency for spontaneous growth of the cause.

(4) tachycardia is often accompanied by atrioventricular block: most of the second degree I or once atrioventricular block, even if the atrial rate is not slow to completely eliminate, but when the sinus rhythm is restored, atrioventricular conduction Blocking disappears, suggesting that the system is blocked by functional blockage in the atrioventricular junction, and the conduction system itself has no organic lesions. The proportion of second-degree type I atrioventricular block is also fluctuating, which can be 3:2,4 3, 5:4 and 6:5, etc., when 1:1 in the atrioventricular conduction, intravenous injection of geranin C can promote the appearance of second-degree type I block.

(5) Sinus rhythm never occurs during the onset of chronic persistent atrial tachycardia.

(6) Chronic persistent atrial tachycardia can last for several days, several years or even more than ten years.

2. ECG characteristics of chronic repetitive autonomous atrial tachycardia

(1) for a series of short-term atrial tachycardia, repeated episodes, the onset time of each atrial tachycardia is generally 1 ~ 7s, individual up to 21s.

(2) The atrial rate of each episode is 94-214 beats/min, and most of them are 100-180 beats/min.

(3) There are 1 to 4 sinus beats between each atrial tachycardia, and more than 3 sinus beats have sinus arrhythmia.

(4) The P' wave and sinus P wave morphology of atrial tachycardia are different: P' wave is erect in II, III, aVF lead, P'-R interval can change with heart rate, heart rate When the difference is not large, it is relatively fixed, ranging from 0.12 to 0.17 s. The interval between P' and P' is different. The slower the frequency is, the more obvious the change is. The difference is 0.04~0.14s, so the RR interval is not equal. The P'-P' interval is gradually shortened, and then progressively extended until the atrial tachycardia is suspended.

(5) The interval between chronic repetitive and spontaneous atrial tachycardia is generally not fixed, the difference is 0.02 ~ 0.24s, may be associated with atrial premature contraction, its interphase and atrial heartbeat The interval between the onset of rapid attack was significantly different, with a difference of 0.04 to 0.22 s.

(6) Some persistent autonomic atrial tachycardia can be converted into short-order repetitive autonomous atrial tachycardia due to factors such as speech and activity. The screen test can temporarily restore sinus rhythm, and then repeat Seizure of autonomic atrial tachycardia, when the stimulation was stopped, the short-term repetitive autonomous atrial tachycardia returned to persistent atrial tachycardia.

(7) In the case of chronic recurrent autonomic atrial tachycardia, second-degree type I atrioventricular block can be combined, accounting for about 30%.

3. ECG characteristics of chronic recurrent reentry atrial tachycardia

(1) Each time the atrial tachycardia is progressively shortened by the sinus cardiac cycle and reaches a critical degree, the recurrent episodes are continuous, and the sinus beat interval shortening rate is smaller (the shortening is more significant), then the adjacent two The more sinus beats between the ventricular tachycardias.

(2) In the recurrent reentry atrial tachycardia, the ectopic P' wave morphology is consistent, and the II, III, aVF leads must be erect.

(3) The first cardiac cycle in recurrent reentry atrial tachycardia may vary in length, the reentry pathway is unchanged or the reentry pathway is changed, and the presence of the proximal common channel on the conduction pathway has not been disrupted. Repeated atriality The tachycardia continues; when the reentry pathway changes significantly for various reasons, the proximal common channel is destroyed, the tachycardia is terminated, and the sinus rhythm is restored.

(4) Atrial premature contraction occurred during the intersegmental period of recurrent reentry atrial tachycardia, and the interval between the interphase and the recurrent reentry atrial tachycardia was significantly different.

(5) Repeated reentry atrial tachycardia can be terminated by itself. The screen test can make the sinus cardiac cycle consistent, and can also terminate the recurrent reentry atrial tachycardia, but digitalis cannot reduce or terminate the repetitive reentry. The onset of sexual tachycardia.

(6) Chronic recurrent reentry atrial tachycardia can be divided into the following two types:

1 When the sinus cycle is progressively shortened to a certain critical value, a sinus P wave that is not prolonged by a PR interval induces atrial tachycardia. The mechanism is that the sinus agitation should be extended somewhere in the conduction path. During the period, 3-phase conduction block occurred to form a reentry atrial tachycardia.

2 The sinus cycle is progressively extended, and atrial tachycardia is induced when the threshold is reached. The mechanism may be 4-phase block.

Diagnosis and diagnosis of chronic autonomic atrial tachycardia

Diagnostic criteria

According to the medical history, symptoms, signs and electrocardiogram performance can be clearly diagnosed.

The diagnostic criteria adopted by Keane et al in 1972 were:

1. The ectopic atrial frequency is not constant. The average frequency is less than 180 beats/min, and rarely exceeds 200 beats/min.

2. The P' wave is easy to identify the frontal electric axis is almost abnormal.

3. The tachycardia is persistent or repeated and persistent, and the two types can change each other.

4. Antiarrhythmic drug treatment is often ineffective.

Differential diagnosis

1. Paroxysmal supraventricular tachycardia is characterized by sudden onset, sudden termination, ectopic frequency is fixed, heart rate is often greater than 180 beats / min, tachycardia episodes last for several minutes, hours to days, but rare For more than 10 days, treatment with antiarrhythmic drugs such as propafenone or ATP can stop the episode.

2. Atrial tachycardia with atrioventricular block This disease is often manifested by digitalis poisoning, or complicated by other serious conditions, such as pulmonary heart disease, hypokalemia, hypoxia, etc., and can further develop into more severe heart rhythm Abnormalities, if not handled in time, can lead to death.

3. The identification of persistent recurrent atrioventricular junction tachycardia (RAVNT) and chronic atrial tachycardia is sometimes difficult, but RAVNT is a circular movement with a reentry mechanism, showing a 1:1 atrioventricular conduction, RAVNT patients. The P-wave axis is often between -90° and +15°; while the chronic persistent atrial tachycardia is often accompanied by varying degrees of atrioventricular block, and the P-wave axis is often between +110° and -90°. Therefore, it can be used for identification.

4. Short-term paroxysmal tachycardia recurrent episodes of short-term atrial tachycardia, which can be induced by swallowing or respiratory movements. Each episode has a short episode, and there is a series of paroxysmal atrial tachycardia. Sinus beat, and there is only 1 to 4 sinus beats between chronic recurrent atrial tachycardia.

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