Pre-excitation syndrome

Introduction to pre-excitation syndrome Pre-excitation is an abnormal phenomenon of atrioventricular conduction. Impulse is transmitted through additional channels, and some or all of the ventricles are excited early, causing some ventricular muscles to be excited in advance. Pre-exciting syndrome is called pre-excitationsyndrome. Or WPW (Wolf-Parkinson-White) syndrome, often combined with supraventricular paroxysmal tachycardia. Pre-excitation is a rare arrhythmia, and the diagnosis depends mainly on the electrocardiogram. basic knowledge The proportion of illness: 0.025% Susceptible people: no specific population Mode of infection: non-infectious Complications: arrhythmia atrial fibrillation

Cause of pre-excitation syndrome

Disease factors (35%):

Also seen in some congenital heart disease and acquired heart disease, such as tricuspid valve down, hypertrophic obstructive cardiomyopathy. Pre-excitation patients may also have atrial fibrillation or atrial flutter episodes. Most of these episodes are caused by impulsive retrogrades, which are caused by atrial vulnerabilities and atrial fibrillation. During atrial flutter and atrial fibrillation, impulsive conduction in the tissue at the junction promotes Most of the impulses are transmitted to the ventricle via bypass, and the ventricular rate is extremely fast. The atrial flutter or atrial fibrillation of the QRS complex is sometimes developed as ventricular fibrillation.

Body factor (55%):

The cause of pre-excitation is the presence of a congenital atrioventricular additional pathway (abbreviated as bypass) outside the normal atrioventricular conduction system. Most patients have no structural heart disease.

Pre-excitation syndrome prevention

Prevention of pre-excitation syndrome is mainly to prevent the recurrence of tachycardia. In order to effectively prevent the recurrence of tachycardia, two drugs should be used to simultaneously inhibit the forward and reverse conduction of the return path, such as quinidine and propranolol. Or procainamide combined with verapamil, can get better results, IA, IC drugs amiodarone or Sol extended progenitor bypass and atrioventricular node irregular, can effectively prevent tachycardia recurrence The drug selection can be determined as an effective drug according to clinical experience or electrocardiographic examination to ensure the best prevention of recurrence.

Pre-excitation syndrome complications Complications arrhythmia atrial fibrillation

The most common complication of this disease is arrhythmia, which is also the reason why this disease needs treatment.

Pre-excitation syndrome itself has no hindrance to health. If arrhythmia does not occur, there is no need for treatment, but those with pre-excitation syndrome have no lifelong arrhythmia. Most of them start arrhythmia in young or middle-aged, a few Arrhythmia occurs in children during childhood or even in infancy, and very few patients develop senile onset. Once arrhythmia occurs, the general rule is that the number of episodes is more and more frequent, each time is longer and longer; the beginning is easily terminated by treatment measures. In the future, the effect will gradually worsen or even be ineffective. The arrhythmia associated with pre-excitation syndrome is mainly atrioventricular reentry supraventricular tachycardia (hereinafter referred to as supraventricular tachycardia); in addition, some patients may also have atrial fibrillation (below) Abbreviated as atrial fibrillation, most patients only have supraventricular tachycardia and no atrial fibrillation; some patients have only had atrial fibrillation in their lifetime, and there has not been any ventricular tachycardia; some patients have both supraventricular tachycardia and atrial fibrillation. Atrial fibrillation can occur alone or from room to overspeed.

Pre-excitation syndrome symptoms common symptoms chest tightness acute respiratory distress ventricular supraventricular arrhythmia tachycardia

Pre-excitation itself does not cause symptoms, but often leads to rapid supraventricular arrhythmia, and supraventricular paroxysmal tachycardia is similar to general paroxysmal supraventricular tachycardia.

The pre-excited ECG features are as follows

(1) Room bypass

The 1 pr interval (substantially the p- interval) is shortened to 0.12 seconds or less, and is mostly 0.10 seconds.

The 2qrs time limit is extended by more than 0.11 seconds.

The beginning of the 3qrs wave group is blunt and forms a setback with the rest, so-called pre-excitation.

4 secondary st-t wave changes.

The above ECG changes are still divided into a and b types. The pre-shock and qrs groups of type a are both upward in the v1 lead, while the pre-shocks of the b-type v1 lead and the main waves of the qrs group are Downward; the former suggests myocardial pre-excitation in the left ventricle or right ventricle, while the latter suggests myocardial pre-muscle in the anterior wall of the right ventricle. This classification method is pre-excited to be a variable qrs group caused by different parts of the bypass. Limitations, but help to distinguish the bypass of the ventricular end in the left or right, front or back, and thus continue to be used today.

(2) Housing

The pr interval of Fangxi bypass is less than 0.12 seconds, mostly at 0.10 seconds; the qrs wave group is normal and there is no pre-shock. This ECG performance is also called short pr, normal qrs syndrome or l, g, l (lown- Ganong-levine) syndrome.

(three) the knot room

The pr interval of the bundle chamber is normal, the qrs group is widened, and there is a pre-shock.

When the pre-excitation syndrome is supraventricular tachycardia, the pre-excitation performance mostly disappears. The electrocardiogram shows the supraventricular tachycardia with normal qrs group shape. When atrial flutter or atrial fibrillation occurs, qrs maintains the pre-excitation characteristics. Rarely, the electrocardiogram is characterized by atrial flutter or atrial fibrillation with a large qrs wave malformation; the ventricular rate is mostly more than 200 beats/min, even up to 300 beats/min, and the atrial flutter can be 1:1 atrioventricular conduction, and may identify the room. In the atrial fibrillation, the ventricular rhythm is irregular. After a long interval, the individual qrs group can be seen in normal shape (probably the extension of the bypass refractory period, after the occult conduction in the atrioventricular node disappears, all or most of the chambers are impulsive. Caused by knot conduction, and may identify atrial fibrillation waves, when the ventricular rate is extremely fast, may also be accompanied by frequency-dependent intraventricular conduction changes.

In addition to the above ECG features, the ECG vector map can be used as a diagnostic basis. The characteristic is that the initial part of the QRS ring on each surface runs slowly in a straight line for up to 0.08 seconds. Afterwards, it suddenly turns and continues to run at normal speed. QRS ring runs. The time can be more than 0.12 seconds. The Hertz beam and the surface or epicardial mapping help to identify the topping and bypass positioning. In confirming whether the bypass is involved in the tachycardia reentry ring. makes an important impact.

Pre-excitation syndrome check

The main examination method for this disease is electrocardiogram examination:

ECG performance: The characteristics of the electrocardiogram caused by each bypass are as follows.

(1) Room bypass

The 1PR interval (essentially the P- interval) is shortened to 0.12 seconds or less, mostly 0.10 seconds;

The 2QRS time limit is extended by more than 0.11 seconds;

The beginning of the 3QRS wave group is blunt and forms a setback with the rest, so-called pre-excitation;

4 secondary ST-T wave changes.

The above ECG changes are still divided into two types, A and B. The pre-shock and QRS complexes of type A are upward in the V1 lead (Fig. 3), while the pre-shock and QRS complexes of the B-type V1 lead are used. The main wave is downward; the former suggests myocardial pre-excitation in the left ventricle or the right ventricle, while the latter suggests the right ventricular anterior wall myocardial pre-muscle. This classification method is subject to pre-excitation and is caused by different parts of the bypass. The limitation of the QRS complex, but helps to distinguish the bypass of the ventricular end in the left or right, front or back, and thus is still in use today.

(2) Fang Jie, Fang Xi Road PR interval is less than 0.12 seconds, mostly at 0.10 seconds; QRS complex is normal, no pre-shock, this ECG performance is also called short PR, normal QRS syndrome or L, G, L (Lown-Ganong-Levine) syndrome.

(3) The junction chamber, the beam chamber connection PR interval is normal, the QRS complex is widened, and there is a pre-shock.

Pre-excitation performance mostly disappeared in pre-excitation syndrome supraventricular tachycardia. The electrocardiogram showed supraventricular tachycardia with normal QRS complex (Fig. 5). When atrial flutter or atrial fibrillation occurred, QRS remained pre-existing. The astigmatism is not uncommon (Figure 6). The electrocardiogram shows a wide atrial flutter or atrial fibrillation with a QRS complex. The ventricular rate is mostly more than 200 beats/min, even up to 300 beats/min, and the atrial flutter can be 1:1. Atrioventricular conduction, and may identify atrial flutter, irregular ventricular rhythm in atrial fibrillation, after a long interval, individual QRS complexes are normal (may be a prolonged refractory period, after the occult conduction in the atrioventricular node disappears, Impulsive all or most of the conduction through the atrioventricular node), and may identify atrial fibrillation, when the ventricular rate is extremely fast, may also be accompanied by frequency-dependent intraventricular conduction changes.

Diagnosis and differentiation of pre-excitation syndrome

diagnosis

Diagnosis can be based on medical history, clinical symptoms, and laboratory tests.

Differential diagnosis

Simple pre-excitation is no symptom, and supraventricular tachycardia is similar to general supraventricular tachycardia. Patients with atrial flutter or atrial fibrillation have a ventricular rate of about 200 beats/min, which can occur except for palpitations and other discomforts. Shock, heart failure and even sudden death, ventricular rate is very fast, such as 300 times / min, auscultation heart sounds can only be half of the ventricular rate on the electrocardiogram, suggesting that half of the ventricular activation can not produce effective mechanical contraction, pre-excitation concurrent supraventricular tachycardia At the time of speed, the QRS complex often does not widen, but there is a characteristic ECG change except for occult pre-excitation after the termination of the attack. When pre-excitation with atrial fibrillation or atrial flutter, the QRS complex often widens and should be associated with ventricular cardiac motility. Overspeed identification.

Pre-excitation pattern on ECG should be differentiated from bundle branch block, ventricular hypertrophy or myocardial infarction, PR interval shortening and pre-shock can be confirmed as pre-excitation, accelerated ventricular autonomic rhythm and sinus rhythm are interfering atrioventricular When separating (especially when the ventricular rate is similar to the sinus heart rate), there may be a short-term PR interval shortening, and the QRS complex broad-form malformation ECG performance, similar to intermittent pre-excitation; but long records often show that the PR interval is not Separation of the fixation and the atrioventricular compartment is not difficult to identify with pre-excitation.

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