Atrioventricular junction zone premature contractions

Introduction to premature contraction of atrioventricular junction The premature contraction of the atrioventricular junction is also called premature beat of the atrioventricular junction (A-Vjunction prematurebeats, JPBs), referred to as the premature ventricular premature beat or the premature contraction. It refers to an excitement that occurs in advance in the atrioventricular junction area before the sinus excitement has not yet been issued. basic knowledge The proportion of sickness: 0.01% Susceptible people: no special people Mode of infection: non-infectious Complications: transient ischemic attack

Premature contraction cause of atrioventricular junction

(1) Causes of the disease

The etiology is similar to the atrial premature contraction, which can be seen in both normal healthy people and in patients with structural heart disease, such as rheumatic heart disease, myocarditis, cardiomyopathy, coronary heart disease, heart failure, and pulmonary heart disease. It is effective to use digitalis, but digitalis poisoning can also be triggered. Hypokalemia can occur. It can disappear after potassium supplementation. When the premature contraction of the junction area is accompanied by atrial premature contraction or ventricular premature contraction. There are myocardial damage, such as acute myocardial infarction, severe myocardial ischemia, myocardial injury, suggesting a serious prognosis.

(two) pathogenesis

1. The autonomy of the atrioventricular junction area has pacemaker cells in the junction area, which is self-disciplined, has the function of automatic depolarization during diastole, and exerts the role of secondary rhythm. Under pathological conditions, such as myocardial ischemia, myocardial Injury, hypokalemia, etc., can lower the threshold potential, diastolic depolarization rate is accelerated, repolarization is inconsistent, causing the membrane potential to increase, so that the autonomy of the atrioventricular junction area exceeds the sinus rhythm and the atrioventricular junction area is pre-existing. shrink.

2. Refraction mechanism The arrangement of fiber bundles in the chamber junction area, the conductivity and refractory period are not completely the same, so functional longitudinal separation, conduction block and inconsistent conduction velocity can be produced, which is the physiological basis for reentry agonism.

3. Triggering activities There are some cross-regional pre-contraction that may be caused by triggering activities, such as premature contraction caused by digitalis poisoning.

Premature contraction prevention in the atrioventricular junction

1. Actively treat the primary disease, eliminate the causes of pre-systolic contraction, such as correcting electrolyte imbalance, improving myocardial blood supply, improving cardiac function, etc.; preventing exogenous; correct, timely medication.

2. Avoid mental stress, maintain mental optimism, emotional stability; daily life, do not overwork; quit smoking and alcohol, reduce the predisposing factors of the disease; diet has a diet, eat less fat and greasy food.

3. Actively exercise and control weight.

Premature contraction complications Complications transient ischemic attack

Severe cases may cause Aspen syndrome due to severe abnormal heart rhythm, causing cerebral ischemia, blackness, palpitation, and syncope. However, this disease usually has a history of primary heart disease. Premature contractions in the atrioventricular junctions generally do not affect ventricular contraction, so clinical complications are relatively rare.

Premature contraction symptoms in the atrioventricular junction area Common symptoms Frail palpitation, chest tightness, heartbeat, heartbeat, dizziness

Patients with premature contraction in the atrioventricular junction area are mainly palpitations, palpitation, intermittent, and the patient's conscious heartbeat is disordered when the number of contractions is too high, and chest tightness, discomfort in the anterior region, dizziness, and fatigue may occur.

During the physical examination, the auscultation found arrhythmia, there was a heartbeat that appeared in advance, followed by a long intermittent pause. The intensity of the first heart sound could change due to the separation of the atrioventricular compartment caused by the contraction of the premature contraction.

Premature contraction examination of the atrioventricular junction

There is currently no relevant information.

Mainly rely on ECG diagnosis.

1. Characteristics of typical ECG before contraction

(1) QRS waves appearing in advance: their morphology is the same as sinus beats.

(2) There may be a retrograde P' wave before or after the QRS wave, or no retrograde P' wave. If the P' wave is in front of the QRS wave, the P--R interval is <0.12 s; if P- is after the QRS wave, then RP - Interval <0.20s (Figure 1).

(3) The compensation interval is generally a complete compensatory interval, and it may also be an incomplete compensation compensation interval.

(4) PII, PIII, PaVF inversion, PV5, PV6 inversion, PaVR, PaVL, PV1 upright.

2. Detailed description of a typical ECG

(1) The premature contraction of the junctional zone is often transmitted along the normal route, so the QRS wave morphology is mostly supraventricular, but sometimes accompanied by indoor differential conduction, QRS wave morphology, and the time limit is different from the supraventricular.

(2) When the P, wave inversion occurs in the PI and PaVR leads, the premature contraction can be excluded.

(3) Compensation interval: When accompanied by retrograde P' wave, it is mostly incomplete compensatory interval, when the retrograde P' wave appears later, for example, in the mid-diastolic or later transitional period, or When the premature contraction is accompanied by a one-time retrograde block, it is a complete compensatory interval. When the ectopic activation in the junction area is delayed by the one-way block at the junction, it cannot be reversed to the atria. 'wave, it is also a complete compensatory interval, when the ectopic agitation in the junction area not only invades the sinus node, but also offsets its early agonism, and can directly inhibit the formation of the next sinus agonism, then A supercomplete compensatory interval can be generated.

3. Special type of premature contraction in the compartmental transition zone

(1) Parallel rhythm compartment intersection premature contraction: ECG features are:

The pre-1 contraction spacing (referred to as the QRS wave) is not fixed.

2 can have atrial fusion wave.

There is a maximum common divisor or integral multiple between the 3rd pre-contraction rhythm spacing.

(2) Premature contraction with atrioventricular junction with forward atrioventricular block:

1 atrioventricular junction premature contraction with forward-onset atrioventricular block: P--R interval greater than 0.12 s can be diagnosed, premature systolic contraction occurs in diastolic phase, and interfering P- The retrograde P- of the -R interval prolonged appeared earlier, mostly in the late stage of contraction or earlier, which is the main distinguishing point of the two.

2 atrioventricular junctional premature contraction with forward third-degree atrioventricular block: only retrograde P' wave at this time, and no QRS wave, can be called undifferentiated atrioventricular junctional premature contraction This should be differentiated from the premature contraction of the transitional zone with interfering atrioventricular conduction (or premature contraction due to interference but not transmitted). The main point of differentiation is the retrograde third-degree atrioventricular block. The P' wave appears later, mostly in the diastolic phase.

(3) premature contraction of the atrioventricular junction with retrograde compartmental block:

1 atrioventricular junctional premature contraction with retrograde once ventricular block: P' wave after QRS wave, PP-interval > 0.20 s.

Premature contraction of the atrioventricular junction with retrograde third-degree ventricular conduction block: At this time, only the QRS wave is seen before the contraction of the premature region, and the retrograde P' wave of the QRS wave before or after disappears. Some scholars believe that it occurs. Absolute interference or physiological room block, the characteristics of electrocardiogram

A. Premature supraventricular QRS waves.

B. No related retrograde P' wave: while there is a sinus P wave, the sinus P wave is often adjacent to the supraventricular QRS wave, or overlaps with the QRS-T wave group, so that the sinus P wave is not easily identifiable.

C. The compensatory interval is complete because there is no sinus rhythm reforming.

D. The premature contraction occurs before the contraction occurs.

(4) Premature contraction of the atrioventricular junction and retrograde atrial and sinus pulsation to form atrial fusion wave: the premature contraction of the premature systolic reversal to the atrium can form atrial fusion with the atrial part of the sinus node Wave, characteristics of ECG:

1 Premature supraventricular QRS wave.

The 2P' wave morphology is between the retrograde P' wave and the sinus P wave.

3 complete compensation for the interval.

The pre-contraction phase is usually delayed: most of the pre-systolic contraction, and the atrial contraction is less likely to form atrial fusion waves than the atrioventricular junction.

(5) Repeated heart rhythm in the atrioventricular junction area: the most common in repeated heart rhythm, the contraction area pre-contraction on the one hand, the excitatory ventricle produces QRS waves, and on the other hand, it is transmitted back to the atrium to generate P' waves, and the P' wave can be along The original route is re-entered, and the QRS wave is generated by the excitatory ventricle along the premature junction area. This is called repeated heart rhythm. If it occurs repeatedly, it forms a repetitive tachycardia. The ECG features of repeated heart rhythm in the atrioventricular junction area are:

1 QRS-P--QRS wave group appears: the first QRS wave is supraventricular, the P' wave is retrograde, the second QRS wave is supraventricular, and it can produce wide deformity due to differential conduction in the room. QRS wave, this second ventricular beat, that is, ventricular retrograde heartbeat, can actually be considered as a special junctional pre-contraction.

The 2R-P-interval is generally >0.20s: if the retrograde is too fast, the compartmental junction area cannot be excited again.

3 The RR interval containing P- is about 0.50 s: that is, the interval between two QRS waves does not exceed 0.50 s, the RP-interval is inversely proportional to the P--R interval, and the longer the RP-interval is P--R The shorter the interval, and vice versa, sometimes the repeated heart rhythm in the atrioventricular junction is not transmitted back to the atria, only reciprocating in the atrioventricular junction, producing a pair of QRS waves that are very close, with no retrograde P' waves between the two, such as When atrial fibrillation occurs, it is impossible to pass it back to the atria.

(6) Atrioventricular junction pre-systolic contraction reverse and forward simultaneous complete atrioventricular block: there is no P--QRS-T wave group on the electrocardiogram, and the performance is a long interval, this is called transmission Before the blockage of the atrioventricular junction, the anterior contraction can occur in occult conduction, so that the PR interval of the posterior sinus beat is prolonged or the P wave cannot be transmitted.

(7) Invasive atrioventricular junctional premature contraction: the principle of production is similar to the insertional (or metastatic) ventricular premature contraction, and the electrocardiographic features are in addition to the premature contraction and ventricular premature contraction. The characteristics of QRS wave are different, other characteristics are similar, and the premature contraction of the insertional intercourse can be due to the latter half of the sinus cycle, but it seems to be delayed, and the determinant is in the premature contraction of the interphase interval. Is the length of the sinus cycle, if the sinus cycle is 2 times longer than the interval of the joint, the premature contraction is located in the first half, such as the sinus cycle is twice as short as the interval, the junction zone The anterior contraction is located in the second half. If the period is equal to twice the interval of the joint interval, the pre-contraction contraction is in the center of the period. If the second law is present, the tachycardia with the absolute rhythm of the rhythm can be used.

(8) occult atrioventricular junctional premature contraction: refers to the premature systolic contraction with bidirectional conduction block, but neither forward conduction stimulating ventricle nor reverse conduction stimulating atrium, but there is handover Concealed conduction in the area, there is no retrograde P' wave on the electrocardiogram, and there is no supraventricular QRS-T wave. This is an "excitatory" that does not produce "pulsation", but this occult conduction is already excited by some chambers. The organization produced a new refractory period that could affect the conduction of the next sinus beat, causing multiple arrhythmias. Wu Xiang (1987) reported the following six types:

1 occult sexual intercourse pre-contraction caused by pseudo-ventricular block: occult cross-regional pre-contraction failed to agitate the atrium and ventricle, but excited part of the atrioventricular junction area tissue, resulting in a new no In the expected period, when the subsequent sinus beats are transmitted to the place, the P--R interval is prolonged if the relative refractory period is encountered. If the absolute refractory period is encountered, the P' wave is transmitted downward, and the former causes Once with atrioventricular block, the latter causes complete atrioventricular block, if the former and the latter occur one after another, the formation of a second degree II or second type I atrioventricular block, of course, these Atrioventricular block is not a true atrioventricular block, but a pseudo-ventricular block, which is a physiological interference phenomenon. Some people believe that the occult interface is caused by pseudo-ventricular block. Pre-contraction, mostly pre-Hybrid contraction.

2 occult sexual intercourse pre-contraction caused by alternating PR interval: occult cross-regional pre-contraction can occur after each sinus beat, which can constitute a rare occult insertional compartment junction Pre-systolic bivariate, at this time, the PR interval of sinus can be alternately changed, pre-contraction can also occur after every 2 sinus beats, forming a occult insertional compartmental transitional period Pre-contraction triple law.

3 occult sexual intercourse pre-contraction can cause second sinus conduction block: occult cross-regional pre-contraction can be occult retrograde conduction to the sinus interface, interfere with sinus agitation, causing second sinus conduction resistance Stagnation, rarely seen.

4 occult sexual intercourse pre-contraction causes "supernormal" atrioventricular conduction: usually in the relative refractory period, the RP interval is inversely proportional to the PR interval, that is, the shorter the RP, the longer the PR, in the case of accidental The relationship between the RP interval and the PR interval changes, that is, the short RP interval, and the subsequent PR interval is also short; the RP interval is longer, and the subsequent PR interval is longer, which suggests that the room exists. "Extraordinary", in fact, this non-physiological compartmental conduction relationship may be due to occult junctional premature contraction.

5 occult sexual intercourse pre-contraction caused by repeated pulsation: in rare cases, a timely handover area pre-systolic contraction, encountering the His bundle Ukrainian system is still in refractory period and can not be forwarded to the ventricle However, the atrium can be slowly retrogradely transmitted, and a retrograde P' wave can be generated. If the ventricle is excited along another path during the retrograde conduction process, a repeated pulsation of the occult atrioventricular junction is formed.

6 occult sexual intercourse pre-contraction can cause delayed compensatory interval: when the premature contraction is issued, the first sinus beat after premature beat is slow because the atrioventricular junction area is still in relative refractory period. Downstream, the second sinus beat because the RR interval is too short, the compartment junction area organization is still in an absolute refractory period and cannot be transmitted, forming a long RR interval, called the delayed compensatory interval.

Characteristics of anterior contraction of occult atrioventricular junction: A. Generally short-term presence, more benign arrhythmia; B. can occur in organic heart disease, can also occur in normal people, atrioventricular conduction The function can be normal, or it can occur on the basis of the lesions in the atrioventricular conduction.

(9) Occult conduction can lead to premature contraction of a variety of different ECG manifestations.

(10) Ventricular phenomenon in the premature contraction of the atrioventricular junction and the reentry pathway in the atrioventricular junction, when the premature contraction (or bivariate) of the frequent intercourse is gradually extended with the pre-contraction interval Until a long compensatory interval occurs, it is suggested that there is a conduction disorder in the reentry path of the atrioventricular junction area. As the contraction of the junction area occurs, the conduction disorder is gradually increased until the pre-contraction cannot pass.

(11) premature contraction of the atrioventricular junction is a joint law or continuous hair: the premature contraction of the atrioventricular junction is a joint law that refers to the fixation of a ventricular sinus after a sinus beat, which can form The second law, the triple law, the fourth law, etc., the premature contraction of the atrioventricular junction is the continuous occurrence of the contraction of the two compartments, the frequency is relatively fast, the P' wave is generally unrecognizable, and its mechanism Most of them are caused by reentry excitability. Pre-systolic continuation is prone to atrioventricular tachycardia.

(12) Premature contraction in the atrioventricular junction with indoor differential conduction: There are two kinds of indoor differential conduction in the premature contraction premature transmission.

1 case atrioventricular contraction with premature contraction with time-differential indoor differential conduction: related to heart rate, occurs when the heart rate is slow and the contraction area premature contraction occurs earlier, one side of the atrioventricular bundle branch has not completely detached Period, so this excitement can only be transmitted from the other side of the bundle to the ventricle, resulting in widening of the QRS wave deformity, which is the time-differential indoor differential conduction, and its electrocardiogram is characterized by: A. The inter-rational period (RR') is mostly short and can be on the T-wave peak; B. The pre-contraction interval pre-period (RR) is relatively long; the CP--R interval is <0.12 s or RP - Interval <0.16s; D. The QRS wave of the premature contraction is often inconsistent with the main wave direction of the sinus QRS wave; the E.QRS time limit is mostly wide, up to 0.12~0.14s; the F.V1 lead The QRS wave is a three-phase complete right bundle branch block (rSR'); the variability of the G.QRS wave is large; H. There is no ventricular fusion wave; I. The His bundle electrogram usually has Ae (more in H2) Before), Ae-H2 interval.

2 ventricular premature contraction with non-temporal indoor differential conduction: no significant relationship with heart rate, ECG characteristics are: A. Pre-systolic contraction interval (RR) is not necessarily shorter; B. The pre-interval period (RR) is not necessarily long; the CP-R interval is <0.12 s, and the RP-interval is <0.16 s; D. The QRS wave of the pre-systolic contraction is inconsistent with the direction of the main wave of the sinus QRS wave; The time limit of QRS wave is more than 0.11s; F.QRS waveform is only mildly deformed, slightly different from sinus QRS waveform; G. no ventricular fusion wave; H. Histogram can have retrograde Ae wave, Ae -H2 interval.

Diagnostic diagnosis of premature contraction in atrioventricular junction

According to clinical manifestations, signs, ECG characteristics, etc. can usually make a correct diagnosis.

Differential diagnosis

1. Identification of differential premature conduction and ventricular premature contraction in the premature contraction of the atrioventricular junction

(1) Identification of differential contraction and ventricular premature contraction in the premature contraction of the atrioventricular junction: both may have a retrograde P' wave, but the RP-interval of the premature contraction <0.12s, QRS wave is a three-phase right bundle branch block type, the waveform is narrow, the time limit is less than or equal to 0.14s, the shape is variability large, there is no ventricular fusion wave, and the PP' interval of ventricular premature contraction Should be greater than 0.12s (due to the far distance from the atrium), mostly single-phase or two-phase type, the waveform is wide and deformed, the time limit is more than 0.12s, the shape is more constant, there may be ventricular fusion waves, in addition, before the period of contraction It is characterized by the first pre-contraction contraction wide deformity before the contraction of the anterior contraction, and the supraventricular contraction QRS wave before the second pre-contraction; and the two pre-expansion of the ventricular pre-contraction The contraction is wide and deformed. If there is a premature contraction of the junction in the same lead without the indoor differential conduction, it is more conducive to the diagnosis of the premature contraction of the transitional zone with the phased indoor differential conduction.

(2) Atrioventricular junctional premature contraction with non-temporal indoor differential conduction: The similarity between the premature contraction and the high-ventricular septal contraction is that the QRS wave is not too wide and the time limit is less than 0.11 s. The inter-law period is not necessarily short, and the QRS wave is easily denatured. The difference is that the direction of the main wave of the QRS wave is inconsistent with the sinus heartbeat, while the latter is more consistent; the former rarely has ventricular fusion waves, the latter can appear. The former may have retrograde P' waves, P--R interval <0.12s, RP-interval>0.16s, or <0.12s; the latter rarely has retrograde P' waves, if any, P' After the QRS wave, the RP-interval must be >0.12 s. For example, >0.20 s is mostly ventricular premature contraction.

2. The premature contraction of the atrioventricular junction and the atrial premature contraction originating from the lower atrium or the left atrium can be inverted P' waves in the II, III, aVF leads, and the aVR lead P' wave Upright, but the former P--R interval <0.12s, while the latter P--R interval should be >0.12s, in rare cases, due to the earlier handover area pre-contraction excitatory When the atrioventricular conduction system is still in the relative refractory period, the PR interval is prolonged to >0.12 s. At this time, the electrocardiogram should be traced for a long time to be confirmed.

3. The identification of premature contraction and sinus conduction block in the atrioventricular junction is usually easy to identify, but only occurs in the premature systolic contraction with complete atrioventricular block (ie, the transitional period without transfer) When the anterior contraction), only one retrograde P' wave is present on the electrocardiogram without the QRS wave, and this P' wave overlaps with the T wave of the previous sinus beat, and is easily misdiagnosed as sinus conduction block or sinus arrest. Just find out the P' wave carefully to identify it.

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