Atrioventricular junction escape and escape rhythm

Introduction to escape and escape rhythm in the atrioventricular junction When the sinus node or atrial activation is not transmitted to the atrioventricular junction area on time, and the interval exceeds the time limit of the self-discipline period of the potential pacemaker in the tissue of the junction area, the potential pacemaker point is the impulse, which is caused by An ectopic heart beat is called junctionalescape. Three or more consecutive escape zones of the transition constitute a junctional escape rhythm (junctionalescaperhythm). basic knowledge The proportion of sickness: 0.01% Susceptible people: no special people Mode of infection: non-infectious Complications: syncope, hypotension

The cause of escape and escape rhythm in the atrioventricular junction

Common causes of handicap escape (45%):

(1) sinus node function is low: mainly sinus bradycardia, when the frequency of sinus rhythm is lower than the junction area, there may be escape in the junction area, acute myocardial infarction, especially inferior wall infarction, in the early stage of the disease 7% to 10% of patients have escape in the junction area, cardiomyopathy, myocarditis and other patients have also occurred.

(2) sinus arrest: after a long sinus arrest, the transition zone escape can be issued, which is seen in myocarditis, after the cardioversion, certain drugs.

(3) sinus conduction block: such as myocarditis, myocardial infarction, digitalis poisoning.

(4) Atrioventricular block: mainly seen in third and second degree atrioventricular block.

(5) Temporal sinus node was temporarily inhibited after atrial contraction.

(6) ventricular premature contraction with retrograde conduction to the atrium: atrioventricular junction area escape and escape rhythm are more common in middle-aged and elderly, rarely seen in children.

Common causes of escape rhythm in the junction area (55%):

Intersection zone escape rhythm is not common, mostly temporary, mainly secondary to sinus conduction block, sinus arrest, obvious, very slow sinus bradycardia and atrioventricular block, itself It is a manifestation of the normal potential autonomic function of the atrioventricular junction area, with protective effects, digitalis poisoning, quinidine poisoning or the use of beta blockers, early blood stasis or atropine can also cause this rhythm, However, it is common in people with heart disease, such as rheumatic myocarditis or other inflammation, sinus node or long-term blood supply to the coronary artery caused by degenerative sinus node, also seen in cardiomyopathy, acute myocardial infarction with sinus bradycardia, conduction Blocking, degeneration of the indoor conduction system, cardiac surgery, electrolyte imbalance, etc. may also occur in patients with such arrhythmia, longer-lasting arrhythmia with obvious sinus node dysfunction, such as sinus node synthesis Solicitation.

Pathogenesis

1. The pathogenesis of the transitional sinus beats When the sinus node or atrial sensation is not transmitted to the atrioventricular junction area on time, and the interval exceeds the time limit of the self-discipline period of the backup pace point in the tissue of the junction area, this reserve The pacing point is an impulse, and if it causes an ectopic beat, it is called the escape zone escape.

2. The pathogenesis of the transitional escape rhythm is the same as that of the atrioventricular junction. The classic transitional escape rhythm refers to a heart rhythm excited by the impulse of the atrium and the ventricle simultaneously in the tissue of the junction area, but more It is common that only the ventricle is controlled by the tissue of the junction area, while the atrium is controlled by the sinus node or the intraventricular pacemaker. If it occurs in the atrioventricular block and the interfering compartment, sometimes the atrium can be completely inactive. In general, a heart rhythm is often referred to as a communicative heart rhythm, referring to the rhythm of the ventricle.

Atrioventricular junction area escape and escape rhythm prevention

Escape rhythm in the junction area and escape rhythm in the junction area is a physiological compensatory mechanism. When it appears, it is necessary to actively search for the primary disease that causes escape in the junction area and escape rhythm in the junction area, ascertain the cause and actively treat the original disease. The cause of the disease is a fundamental measure to prevent such arrhythmia.

Escape and escape rhythm complications in the atrioventricular junction Complications, syncope, hypotension

Long-term handover escape rhythm, when the ventricular rate is too slow, complications such as syncope and hypotension may occur.

Atrioventricular junction area escape and escape rhythm symptoms common symptoms shortness of breath, bradycardia, bradycardia, atrioventricular block, sinus arrest

1. The clinical manifestations of crossover escape are mostly caused by basic heart disease and sick sinus syndrome, sinus bradycardia, sinus block, sinus arrest, atrioventricular block, etc. The escape itself has no obvious symptoms.

2. The clinical manifestations of the interface escape rhythm: The communicating rhythm itself does not have obvious hemodynamic disorder. The symptoms of most patients are caused by primary heart disease, such as palpitations, shortness of breath, etc. The physical examination rate is 40-60. Times / min, the first heart sound intensity has no obvious change, such as a slow transitional heart rhythm, heart rate <40 times / min, may have dizziness, palpitations, syncope and other symptoms.

Examination of escape and escape rhythm in the atrioventricular junction

1. ECG characteristics of handover escape

(1) Typical ECG features:

1 QRS wave that occurs after a longer intermittent cardiac cycle: its shape, the time limit is supraventricular.

2 Most of the junction area escape can not see P' wave: a few can see a retrograde P' wave before and after the QRS wave, P' wave inversion in II, III, aVF lead, erect in aVR, V1 lead, retrograde P' Waves can appear before the QRS wave (P--R interval <0.12 s), or after the QRS wave (RP-interval <0.20 s), or buried in the QRS wave (Figure 1).

3 If there are several escapes in the junction area, each escape period is fixed.

4 Sometimes sinus P waves can occur before and after the QRS wave, but the PR interval is <0.10s (Fig. 1).

(2) A detailed description of typical ECG features:

1 Because the self-discipline of the junction area is lower than that of the sinus node, the anterior period of escape in the junction area is longer than the sinus period, generally 1.0 to 1.5 s. On the same electrocardiogram, the appearance of escape is often and before. A heart beat is separated by a fixed time, that is, an escape period. If there are several escape zones, the escape period is constant, and the phase difference should be <0.08 s.

2 Because the excitability of the escape in the junction area is transmitted to the ventricle according to the normal atrioventricular conduction system: so the QRS wave shape, the time limit is the same as the QRS wave of the sinus, but the QRS wave may be deformed if the phase difference indoor conduction occurs. Since this is a delayed heartbeat, it cannot be explained by the fact that the conduction block is still in the relative refractory period, but the mechanism of its occurrence is still unclear.

3 retrograde P' wave: the activation of escape in the junction area is transmitted to the ventricle through the normal atrioventricular conduction system; on the one hand, most of the conduction through the middle internodal or posterior interfacial to the atrium, the depolarization vector of the atria The upper left, so the P ring on the frontal surface is -60 ° ~ -90 °, projected on the negative side of the II, III, aVF lead axis, P wave inverted, is a retrograde P' wave, projected on the aVR lead axis The positive side P wave is erect: projected on the positive side or equipotential side of the I lead axis, and the P wave of the I lead is erect, low or bidirectional.

4 retrograde P' wave and QRS wave relationship: most of the junction area escape can not see the retrograde P' wave, but in a small number of cases can see the retrograde P wave before and after the QRS wave, this is because the junction area escape The pacemaker is excited, and the forward conduction is related to the speed of the reverse conduction, and also to the position of the pace point. For example, when the excitation of the pacemaker is faster than the forward conduction, the retrograde P wave In the QRS wavefront (P'-R<0.12s); when the excitatory preamble is faster than the backpropagation, the retrograde P-' wave is after the QRS wave (RP-<0.20s); when the excitatory pretransmission and the retransmission are equal, Then the P' wave is superimposed on the QRS complex.

5 Before and after the escape of the escape in the junction area: If the sinus node also sends an impulse and controls the atrium, the sinus node will control the atrium, and the transition zone will control the ventricle. The excitement in the atrioventricular node Interference occurs, sinus arousal can not be transmitted to the ventricle, and the escape of the escape zone can not be reversed into the atria. At this time, the sinus P wave can be before the QRS wave, but the PR interval is <0.12s, often within 0.10s, the sinus The P waves may also be located after or overlapping the QRS waves.

6 The excitatory reversible afferent into the atriosphere: the sinus agitation meets in the atrium to form an atrial fusion wave, which is between the retrograde P' wave and the sinus P wave morphology.

(3) Special types of escape in the atrioventricular junction area:

1 Accelerated transition zone escape and transition zone escape function is low: Accelerated transition zone escape refers to the escape of the atrioventricular junction zone under the same conditions as the escape, but the period of occurrence is shorter than 1.0s, Even less than 0.7s, suggesting that the myocardial interventricular junction area tissue has an abnormally high self-discipline. On the contrary, there is also a sinus arrest for more than 4.0s before the myocardial interventricular transition zone escape, and even more arrest Prolonged and no escape, suggesting that the pacing function in the atrioventricular junction is abnormally weak or inhibited (Fig. 1B).

2 The slow transition of the atrioventricular junction: the escape cycle > 1.50s, frequency < 40 beats / min (Figure 2).

3 escape - capture the second law: also known as pseudo-repetitive rhythm, more common in the sinus block, ECG features: after each escape zone escape, followed by a sinus beat, such stimuli capture the ventricle The P-QRS-T wave, P wave is sinus, mostly seen in PP is too long, more than the sum of the escape time and the refractory period after the escape (Figure 3).

2. ECG performance of handover escape rhythm

(1) Typical ECG features:

1 There are 3 or more transition zones in succession (Fig. 4).

2 ventricular rate is slow: 40 ~ 60 times / min, rhythm neat RR interval is equal.

The 3QRS wave is normal or accompanied by differential conduction in the room.

There may be a retrograde P' wave before or after the 4QRS wave: or overlap with the QRS wave. If the QRS wavefront has a P' wave, the P--R interval is <0.12s. If there is a P wave after the QRS wave, the RP-interval is < 0.20s.

(2) A detailed description of a typical electrocardiogram:

The escape rhythm of the 1 room transition zone is slow and uniform: the frequency is 40-60 beats/min, and the RR interval is longer than the sinus cycle, and is equal to the pre-apnea period. The frequency of the child is 80 within 1 year. ~100 times/min, 58 to 80 times/min for 1 to 6 years old, the same as adults for 7 to 14 years old, the rhythm of the escape stroke in the junction area is usually neat, but it is also different, the RR interval varies, the difference can be >0.12s, the reason is: A. At the beginning of the handover escape rhythm, a short preparation process is needed, that is, the initial RR interval is long, and then gradually shortened until stable, which is called the starting phenomenon; B. In the handover area, occult room handover was captured, which made the handover area excited in advance, and the rescheduling period was needed to delay the impulse of the next handover area; C. The impulse of the escape stroke of the escape rhythm in the atrioventricular junction area was uneven. .

2 In most cases, the atrial heart rhythm of the transition zone is controlled by the sinus node: the ventricle is controlled by the junction zone, and the impulse of the junction zone can be reversible to the atrium. It can meet the sinus impulse in the atrium to form atrial fusion wave, sinus Impulsiveness can also be passed down to the ventricular capture.

3 In rare cases: there are 2 pace points in the junction area, the upper pacing point can cause retrograde P' waves; the lower pacing point is transmitted to the ventricles to generate QRS waves, and their frequencies are different.

4 The escape rhythm of the junction area is usually not affected by the stimulation of the vagus nerve, such as the lack of movement, carotid sinus massage, oppression of the eyeball, etc., but can change with the speed of the heart rate, when the heart rate increases, the escape rhythm of the junction area can disappear. Turned into sinus rhythm; when the heart rate slows down, the sinus rhythm can be transformed into the escape zone heart rhythm, which is the frequency-dependent 3-phase transition zone escape rhythm.

(3) Special types of escape rhythm in the atrioventricular junction area:

Escape rhythm with conduction block in the 1 compartment transition zone: in the transition zone escape rhythm, the P'-R interval >0.12s should be diagnosed as a forward conduction block; the RP-interval>0.20s should be diagnosed Once the reverse conduction block, can also be combined with second degree atrioventricular block, the forward two-degree block Venturi type does not occur often, the British type is rare.

A. Atrioventricular junction area escape rhythm with a forward conduction block (Figure 5).

B. The escape rhythm of the atrioventricular junction with a one-time reverse conduction block (Figure 6).

C. Atrioventricular junction area escape rhythm with second degree I retrograde atrioventricular block (Figure 7).

D. Atrioventricular junction escape rhythm with second degree I anterior atrioventricular block (Figure 8).

E. Atrioventricular transition zone escape rhythm with third degree atrioventricular block (Figure 9).

2 Ventricular rhythm in the junction area with Venturi's phenomenon of frequency-dependent bundle branch block (Fig. 10).

Repeated rhythm formed by escape rhythm in the 3 compartment transition zone: When the ectopic heart rhythm is accompanied by retrograde atrial conduction, sometimes this excitement can be transmitted back to the ventricle to cause another ventricular activation, forming a repeated heart rhythm, which is common in the atrioventricular junction Easy heart rhythm, ventricular tachycardia and ventricular premature contraction, etc., the basis of which is the uneven inhibition of conduction at the junction of the atrioventricular junction, some of which are heavier and the other part is lighter, and the area with heavier blockage There is a one-way block (Figure 11).

Repeated heart rhythm ECG diagnosis: retrograde P' wave appears in the junction area or ventricular ectopic activation, the RP interval is extended by more than 0.20s, and then another pre-existing QRS complex (QRS-P--QRS) Compared with the QRS complex before it is <0.50s, when the retrograde atrial conduction RP interval of the escape rhythm of the junction is gradually prolonged, it is easy to repeat the rhythm after the longest RP-interval, and the repeated recurrence of the heart rhythm is easy. Pre-contraction, continuous occurrence of repeated heart rhythm tachycardia.

Repeated rhythm should be differentiated from incomplete atrioventricular separation and ventricular capture (ie, escape-capture) pseudo-repetitive rhythm, which is most common in digitalis sensitive or excessive.

The escapement rhythm of the 4-compartment interface was associated with ventricular premature contraction (Fig. 12).

The 5-compartment junction area escape rhythm forms the escape zone-repetition heartbeat-atrial contraction triad (Figure 13).

Diagnostic diagnosis of escape and escape rhythm in the atrioventricular junction

Diagnostic criteria

The escape zone itself is a secondary physiological phenomenon that has a protective effect. The transition zone escape that occurs too early (less than 1.0s) or too late (more than 1.5s) has pathological significance in itself, so be familiar with it. The characteristics of escape and escape rhythm are important for correct diagnosis.

1. Compared with the period of the dominant rhythm, the delay occurs, the escape period is greater than one sinus cardiac cycle, and the frequency is mostly 20 to 60 times/min.

2. escape cycle: during the same time, the escape cycle is generally fixed, and the escape cycle time is equal. In the Holter examination, it is found that the escape may occur in different states and at different times, and the cycle may vary. Seen on a regular ECG.

3. At the same time, the rhythm of escape rhythm in the same state is regular, but it can also be irregular, and the escape rhythm is not matched.

4. For the time of escape and escape rhythm, there are atrioventricular block, can occur at any time, without atrioventricular block and sinus node pacing and conduction function is good, mainly occurs in the evening sleep And during lunch breaks, and the state of activity and waking state are rare.

5. The escape and escape rhythm lack afferent block. Once the sinus heart rate is >60 beats/min, the escape and escape rhythm pacemakers are suppressed. Therefore, both are passive rhythms.

Differential diagnosis

1. Identification of escape rhythm and atrial escape rhythm in the junction area escape stroke heart rhythm P--R<0.12s, can occur in sinus arrest; and atrial escape rhythm P--R>0.12s, Generally do not occur in sinus arrest.

2. The intersection area escape rhythm with indoor differential conduction and ventricular escape rhythm identification intersection area escape rhythm with indoor differential conduction ventricular rate of 40 ~ 60 times / min, QRS wave is mildly deformed, mostly Right bundle branch block pattern, time limit <0.11s, more ventricular fusion wave, ventricular escape rhythm, ventricular rate is 20 ~ 40 times / min, QRS wave wide deformity, mostly single-phase or two-phase, The time limit is >0.12s, and there may be a ventricular fusion wave.

3. The intersection of escape rhythm and accelerated intersection area escape rhythm. The former ventricular rate is 40 ~ 60 times / min, which is the passive rhythm of the atrioventricular junction; while the latter ventricular rate is 70 ~ 140 times / min, is The active heart rhythm of the room junction area.

4. Identification of escape rhythm in the junction area and parallel heart rhythm in the junction area. The former is prone to rhythm reforming due to no protective afferent block around the pacemaker; the latter has afferent protective properties around the pacemaker. The mechanism generally does not have rhythm reforming, and the long R--R-interval of the contraction of the heart rhythm before the junction is an integer multiple of the short R--R-interval, while the former has no such rule.

5. The intersection of the retrograde P' wave and the sinus node-intersection zone. The rhythm of the latter is characterized by the pacing point of the sinus node gradually moving to the atrioventricular junction, so the P wave The morphology is gradually shifted from the sinus P wave to the reverse P' wave, while the former after a series of sinus P waves, suddenly appear 1 or 2 retrograde P' waves and then sinus P waves, not migration.

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