Atrioventricular reentrant tachycardia

Introduction to atrioventricular reentry tachycardia The incidence of atrioventricular reentrant tachycardia (AVRT) is second only to atrioventricular nodal reentry tachycardia (AVNRT), accounting for approximately 30% of all supraventricular tachycardia. basic knowledge The proportion of illness: 0.0025% Susceptible people: no special people Mode of infection: non-infectious Complications: syncope, angina pectoris, cardiogenic shock, hypotension

The cause of atrioventricular reentry tachycardia

(1) Causes of the disease

The incidence of occult pre-excitation syndrome with AVRT is not clear. According to the tracking of 90 infants with pre-excitation syndrome, about 50% of patients with AVRT at the age of 30, AVRT patients with occult bypass involvement. From children to the elderly, younger people are more, young patients are often without organic heart disease, older patients can be accompanied by a variety of organic heart disease, most pre-excitation syndrome with AVRT patients Clinically, there is no basis for organic heart disease. A small number of patients may be associated with hypertrophic cardiomyopathy and rheumatic heart disease.

(two) pathogenesis

1. Pre-transmission type AVRT Also known as forward-sense, the orthodromic form of tachycardia is transmitted to the ventricle along the atrioventricular node, and then transmitted back to the atria by the atrioventricular bypass to form a pre-transmission type AVRT (also known as OAVRT). There are two types of atrioventricular bypass bundles that cause pre-transmission AVRT:

(1) occult atrioventricular bypass bundle: the reason for its concealment may be due to the abnormality of the front leaflet to block and anatomical structure, which is manifested as the ability to retrograde only the room, which is called "occult pre-excitation syndrome". The electrocardiogram showed no pre-shock, the QRS wave was normal. When a timely atrial contraction occurred, and the inter-term interval was short to the critical value, it may fall into the effective refractory period of the bypass, and then excited along the atrioventricular node. The ventricle is transmitted to the ventricle, and then returned to the atria through the bypass that has been detached from the refractory period, and the atrium is excited, and then passed to the ventricle from the atrioventricular node, and then passed back from the atrioventricular bypass to the atria. Such repeated reentry forms a pre-transmission AVRT. .

(2) Dominant bypass bundle: The bypass has conduction bidirectionality. In sinus rhythm, sinus activation is transmitted to the ventricle along the atrioventricular bypass, and typical ECG patterns of pre-excitation syndrome may occur. When the timely atrial contraction is prematurely contracted, the atrioventricular bypass is in an effective refractory period. Excited can only pass through the atrioventricular compartment and then pass through the atrioventricular bypass to the atrium, and then follow the room. Under the knot, such repeated reentry forms a pre-transmission AVRT.

In sinus rhythm, when the effective refractory period of the bypass and the atrioventricular node is quite different, due to the wide "echo zone", timely pre-contraction or return stroke may cause reversed compartment conduction of the bypass. In order to produce pre-transmission AVRT, timely pre-systolic contraction can be caused by premature contraction of the ventricle, atrium or junction area, but ventricular premature contraction is most common.

2. Antidromic AV reentrant tachycardia (AAVRT) referred to as retrograde reentry tachycardia, also known as retrograde atrioventricular reentry tachycardia, the mechanism of AAVRT is: occult side The road can not participate in the formation of retrograde atrioventricular reentry tachycardia, because occult bypass can not be forwarded, one-way block, and only dominant bypass can participate in the formation of AAVRT, atrial impulse from the atrioventricular bypass to the ventricle (Bypass is the anterior branch), the ventricular activation is first depolarized, so the QRS wave is wide and deformed when the tachycardia is over, often full pre-excitation, the impulse of the ventricle is reversed from the Xi-Pu system, and the atrioventricular node is returned to the atria, so the inverse The order of P' wave transmission is the leading position in the atrioventricular junction. The timely atrial contraction or ventricular premature contraction can induce AAVRT. Atrial and ventricular pre-stimulation can also induce AAVRT.

3. Multiple atrioventricular bypass reentry tachycardia Multiple atrioventricular bypass (MAAP) refers to two or more additional muscle bundle bypass connections between the atrioventricular compartments, which can constitute a large reentry ring in the heart. One of the bypasses performs the forward conduction of the atrioventricular compartment, and the other bypass performs the reverse conduction of the atrioventricular compartment. The multiple compartmental bypasses include the reentry between the bypass and the bypass, and the reentry between the Kent beam and the Mahaim bundle. More common.

(1) Reentry between bypass and bypass: When there are multiple bypasses in the heart, both left and right hearts can exist, and timely atrial premature contraction or return stroke along the right bypass as the atrioventricular antegrade Conduction, causing ventricular activation, at this time, if the left bypass is relatively refractory period, ventricular activation is reversed back to the atrium along the left bypass, and then bypassed from the atrium along the right side of the ventricle, ventricular activation along the left side The bypass is reversed to the atrium, so that multiple atrioventricular bypass reentry tachycardia between the atrioventricular compartments is formed.

The diagnosis of multiple atrioventricular bypass has certain difficulties. Electrophysiological examination is very important. Firstly, the presence of compound bypass can be detected. The right atrial programmable scanning and His bundle pacing can exclude the atrioventricular node double path conduction and Mahaim type. Pre-excited junction conduction, followed by stimulation at different frequencies and locations to clear the site and refractory period of bypass, provide an accurate basis for the diagnosis and treatment of multiple atrioventricular bypass.

(2) The reentry between the Kent beam and the Mahmim beam: When the Kent beam and the Mahaim bundle coexist, a reentry between the two can occur, which can be expressed as: Kent beam for cis-ventricular conduction, Mahaim beam for reverse chamber conduction; Kent The beam is reversed, and the Mahaim beam is used for antegrade conduction. It has the same characteristics as AAVRT on the electrocardiogram: wide QRS wave tachycardia, rhythm rule, equal RR interval, and wave at the beginning of QRS wave. Electrophysiological examination, such as Kent bundle for cis-ventricular conduction, Mahaim bundle for reverse chamber conduction, His's beam diagram can trace the excitation sequence of Ae-Ve-Ae-Ve, there is no H wave between VA, this factor When excited to reverse conduction along the Mahaim beam, the ventricular activation wave V can bypass the His bundle to return to the atria, and the wave appears when the His bundle pacing, which proves the existence of the Mahaim bundle, the Mahaim bundle between the atrioventricular node and the ventricular muscle. When making a room reentry, the Histogram can only be traced to Ve-Ve-Ve, without He, but the A wave and Ve are separated.

(3) The end of the Mahaim bundle or the reentry between the nodule bypass and the bundle bypass: the anatomical basis of this type of supraventricular tachycardia is not fully understood and is still controversial. One is the end of the Mahaim bundle. Or the bundle of chambers, the other is the bundle next to the bundle, the end of the Mahaim bundle or the junction bundle is located in the right posterior septum, and the bundle bypass is located in the right anterior compartment, they are from the atrioventricular node or atrium to the right bundle branch ( Individual reports are taken to the left bundle branch), usually the ECG is normal or presents different degrees of left bundle branch block, and the tachycardia is:

1 compartment conduction time is gradually extended;

2 The vast majority of LBBB type QRS waves, the end of the Mahaim bundle or the atrioventricular conduction of the ventricular bundle through the atrioventricular node, the AH gradually prolonged during the pacing; the bundle bypass itself may have incremental performance, the lower atrial stimulation makes complete Pre-excitation, it can be seen that the right bundle branch potential appears before HB, the end of the Mahaim bundle or the back chamber bypass reverse function is poor, the atrium is not a reentry pathway, so the tachycardia often presents atrioventricular septum, and the bundle bypass tachycardia There must be a heart to participate.

Atrioventricular reentry tachycardia prevention

1. During chronic treatment, drug therapy may control recurrence by directly acting on the reentry loop, or by inhibiting triggering factors, such as spontaneous premature contraction. The indications for chronic drug treatment include frequent episodes, affecting normal life or severe symptoms. Patients who are unwilling or unable to receive catheter radiofrequency ablation may be treated with medication for occasional, episodes of short-lived, or mild symptoms, or medication when needed for a tachycardia episode.

2. Avoid spicy food, stimulate food; quit smoking, coffee, food should be light.

3. Prevention of recurrence of frequent episodes, long-term symptoms of obvious symptoms, prevention of seizures after termination.

(1) Drug prevention: Any drug that can control acute attacks can prevent recurrence in principle, but prevention of recurrence is not as effective as controlling acute attacks. Commonly used drugs are digoxin, verapamil, beta blockers, amiodarone, propafenone (heart rhythm) and so on.

(2) catheter ablation: the current ablation treatment of this disease has achieved good results, is the method of its cure.

(3) anti-arrhythmia pacemaker: those who are ineffective in both drug and radiofrequency ablation may consider placing a pacemaker. The main indications are those who are ineffective or unable to tolerate drug treatment, and who have recurring symptoms that cause obvious symptoms; those who can be repeatedly induced and terminated by electrical impulse stimulation.

Complications of atrioventricular reentry tachycardia Complications syncope angina pectoris shock hypotension

Atrioventricular reentry tachycardia occurs in patients with organic heart disease, or in patients with retrograde atrioventricular reentry tachycardia. Because of the rapid ventricular rate, long-term duration can be combined with syncope, angina pectoris, cardiogenic shock, Low blood pressure, and can induce heart failure. In severe cases, complications such as sudden death can occur.

Atrioventricular reentry tachycardia symptoms Common symptoms Dizziness atrioventricular block Chest tightness heart failure palpitations angina pectoral dizziness

1. The clinical manifestations of pre-transmission atrioventricular reentry tachycardia. The onset of AVRT is early, there may be palpitations during the attack, pre-cardiac discomfort or angina pectoris, dizziness, severe blood pressure reduction, shock and cardiac insufficiency, AVRT attack The heart rate can be slightly faster than AVNRT, but it is mostly in the same range. The heart rhythm is absolutely regular, the heart sound is strong and weak. When the tachycardia is over-expanded, the atrial expansion and anti-diuretic sodium excretion factor secretion increase, and the urinary tract can occur after the tachycardia is terminated. The clinical symptoms are related to the speed of tachycardia and whether hemodynamic disorder is caused. In addition, it is related to the recurrence of tolerance. The general heart rate is more than 160 beats/min, that is, palpitations, chest tightness, more than 200 times/min. There may be blood pressure drop, dizziness and even syncope.

2. The clinical manifestations of retrograde type atrioventricular reentry tachycardia The clinical symptoms and clinical course are both heavier and more dangerous than the pre-transmission atrioventricular reentry tachycardia. The heart rate at the onset is 140-250 beats/min. Often around 200 beats/min, the hemodynamic abnormalities of AAVRT are similar to ventricular tachycardia. When the heart rate is above 150 beats/min, obvious symptoms and hemodynamic disorders can occur, often with angina pectoris. Cardiac shock or syncope, severe cases can lead to ventricular arrhythmia, and even sudden death.

Examination of atrioventricular reentry tachycardia

Mainly rely on ECG and cardiac electrophysiological examination.

Electrocardiogram examination

(1) ECG characteristics of prefabricated atrioventricular reentry tachycardia:

1 typical ECG features:

A. Heart rate 150~240 times/min: mostly 200 times/min, sudden sudden stop.

B. P' wave: The initial atrial P' wave is different from the P' wave shape during tachycardia, and certainly different from the sinus P wave. When the tachycardia is absent, the atrium and the ventricle cannot be excited at the same time. Retrograde P' The wave occurs after the ventricular activation is completed, so the P' wave always appears after the QRS wave (R-P-), the RP-interval 70ms, and the RP-interval/P--R interval<1, the P' wave The II, III, and aVF leads are inverted (Figure 1).

C. Timely atrial premature contraction or ventricular premature contraction spontaneous or electrical stimulation can induce and terminate seizures (Figure 2).

D.38% of patients may have QRS wave alternation.

E. Induced heartbeat (pre-atrial contraction) at the onset of tachycardia, there is no sudden prolongation of P'-R interval, indicating that AVRT does not require the involvement of atrioventricular node dual channel.

F. Exciting the vagus nerve (such as using carotid artery compression) can terminate tachycardia.

G. At the beginning of the onset of tachycardia, functional bundle branch block is prone to occur. If the bundle branch block occurs on the same side of the bypass, the RR interval is extended by more than 30ms; if the bundle branch block occurs on the opposite side of the bypass, Then the RR interval does not change.

H. The normal QRS waveform can appear in the same episode, and the QRS waveform of the bundle branch block can also appear. The heart rate of the two branches is compared. The bundle branch block is slower, and the room conduction is longer than normal by 30ms (Fig. 3 ).

I. Atrium, ventricle, atrioventricular conduction system and bypass are essential parts of the reentry ring: therefore, tachycardia always maintains a 1:1 atrioventricular relationship, such as at least 2 degrees of atrioventricular block, when there is AVRT should be excluded when leaking.

J. Dominant pre-excitation bypass-induced AVRT: When the tachycardia attacks, the delta wave disappears, and the typical pre-excitation syndrome appears in the absence of seizures. The PR interval is short, the wide QRS waveform, and the delta wave.

2 detailed description of typical ECG features:

A. Frequency: The frequency of AVRT in PSVT is the fastest, up to 250 ~ 300 times / min, often around 200 times / min, can be occasional or repeated episodes, can also be a persistent episode.

BP wave: its electric axis depends on the part of the atrioventricular bypass bundle in the atrium, and the frontal electric axis: mostly from the bottom up, so P-II, P-III, P-aVF, a few are intermediate, P -II upright or two-way, P-III bidirectional or inverted, horizontal electric axis: from right to left, P-V1 is inverted, P-V5 is upright, prompting right bypass; from left to right, performance is P-V1 is upright, P-V5 is inverted, and the prompt is left rear bypass. Generally, P-II, P-III, P-aVF, P-V5 are inverted. When tachycardia is reversed, PI is inverted, suggesting that the room is next to the room. The road is located between the left side rooms.

C. P' wave appears after QRS wave: 90% of pre-transmission AVRT patients have a P' wave originating from 70 to 100 ms after QRS wave, and RP-interval is 70 ms. The P' wave of about 5% OAVRT patients originates from The second half of the RR interval.

D. Because the pre-atrial contraction agonism is transmitted from the normal atrioventricular node: the first heartbeat P'-R interval at the onset of the attack is normal.

E.QRS wave voltage alternation (1mm): About 38% of OAVRT patients have electrocardiogram QRS waves alternating with electricity, with II, III, aVF and V1~V4 leads are more obvious, about 23% of QRS wave alternating with ventricle The rate is related, the frequency is fast, and the electric alternation is easy to occur. Some people think that the QRS wave alternation is a characteristic performance of OAVRT, the diagnostic specificity is 96%, and the prediction accuracy is 92%.

F. When ventricular tachycardia occurs with functional bundle branch block: the circumference of tachycardia is prolonged, and the RP interval is prolonged, suggesting that the atrioventricular bypass bundle is the reverse branch of the reentry, and is located on the same side of the block bundle, due to OAVRT The frequency is often faster than other types, and the initial heart beat is forward conduction through the normal atrioventricular pathway. When the joint interval is short and the bundle branch function is not refractory, the bundle branch block is easily formed, once initiated. The heart beat is blocked in one bundle branch, and the reverse occult conduction during tachycardia forms a continuous functional bundle branch block, while the slow-fast AVNRT has its initial atrial premature contraction dysfunction. The forward conduction is through the slow path of the atrioventricular node, which makes the interventricular interval longer than the undulation period of the bundle branch, so the functional bundle branch block is not easy to form during AVNRT.

3 The special type of anterior-posterior atrioventricular reentry tachycardia: Shi Bing et al (1997) reported that 800 patients with AVRT confirmed by transcatheter radiofrequency ablation, the special types seen in esophageal electrophysiological examination, as follows:

A. Prefabricated atrioventricular reentry tachycardia with atrioventricular nodal pathway (DAVNP) has the following three phenomena:

a. The pre-transmission atrioventricular reentry tachycardia is transmitted forward through the atrioventricular node slow pathway (Fig. 4).

b. The pre-transmission atrioventricular reentry tachycardia was alternately transmitted to the ventricle via the fast path (FP) and slow path (SP) of the atrioventricular node (Fig. 5).

c. The pre-transmission type atrioventricular reentry tachycardia is transmitted through the slow path, and the reverse transmission is followed by two bypasses (Fig. 6).

B. Prefabricated atrioventricular reentry tachycardia with functional bundle branch block (FBBB): Functional bundle branch block is a common feature of prefabricated atrioventricular reentry tachycardia, accounting for 21.4%, functional bundle The branch block usually disappears spontaneously after the AVRT continues, and the functional bundle branch block is mostly a continuous short array, which is rare in 2:1.

a. Pre-transmission atrioventricular reentry tachycardia functional 2:1 right bundle branch block (Figure 7).

b. Pre-transmission atrioventricular reentry tachycardia with functional left bundle branch block (FLBBB) (Figure 8).

C. Pre-transmission atrioventricular reentry tachycardia coexists with other types of supraventricular tachycardia. The same patient can induce two different supraventricular tachycardias at the time of examination, that is, multiple sites and multi-path reentry.

a. The pre-transmission type atrioventricular reentry tachycardia coexists with the reentry tachycardia (Fig. 9).

b. Pre-transmission atrioventricular reentry tachycardia coexists with slow-fast atrioventricular nodal reentry tachycardia (Figure 10).

D. Fracture conduction of the bypass: less common, its formation must have three conditions: a. There are two horizontal planes with inconsistent refractory period in the forward conduction path; b. The bypass should not be longer than the atrial muscle Refractory period; c. When the atrial muscle is in the relative refractory period, S2R is prolonged when the program-controlled stimulation is reached, and when the activation reaches the proximal end of the bypass, the bypass is detached from the refractory period and can be stimulated to transmit the excitatory. The pseudo-fracture phenomenon of the ventricle is transmitted under the activation of the internal reentry (Fig. 11).

E. Multi-chamber bypass involved in atrioventricular reentry tachycardia: observation of esophageal electrocardiogram of multiple bypass-related prefabricated atrioventricular reentry tachycardia and atrioventricular nodal pathway involved in prefabricated atrioventricular reentry tachycardia The laws of speed are different. Shi Bing et al believe that there are the following differences: OAVRT with multiple bypasses is characterized by inconsistent RR intervals, inconsistent P-EP-V1 time intervals, inconsistent RP-intervals, and often long RP-interval periods. The PR interval is short, the RP' interval is short, and the P--R interval is long. The OAVRT involved in the atrioventricular nodal pathway is characterized by a constant RP-interval, a long PR interval, and a short period. The difference is 50ms, and the RR interval has a long or short period alternately or intermittently. These two points contribute to the identification of the two (Figure 12).

(2) Electrocardiogram characteristics of retrograde type atrioventricular reentry tachycardia:

1 typical ECG features:

A. Heart rate is 150-250 times/min, mostly about 200 beats/min, absolutely neat.

B. The retrograde P' wave appears after the QRS wave and is located in the first half of the RR interval. However, due to the large width of the QRS wave, it is often difficult to see or easily identify the retrograde P' wave. If the P' wave can be found, then P The wave-to-ventricular QRS wave has a 1:1 ratio (this facilitates the identification of ventricular tachycardia), and the P' wave is inverted on the II, III, aVF leads, RP-/P--R>1.

C.QRS wave width deformity: a complete pre-excitation pattern, time > 0.12s, mostly about 0.14s, showing a wide QRS wave tachycardia (Figure 13).

D. Timely electrical stimulation can induce and terminate seizures.

E. Using stimulating vagus nerves such as carotid compression can terminate tachycardia.

(3) ECG characteristics of multiple atrioventricular bypass reentry tachycardia:

1 sinus rhythm atrial activation through different bypasses of the ventricle caused by electrical axis changes, the graphics vary.

2 cases of atrioventricular bypass: When the pre-existing and retrograde atrioventricular reentry tachycardia alternated, the cardiac cycle was inconsistent due to changes in the reentry pathway (Fig. 14, 15).

2. Characteristics of electrophysiological examination

(1) Characteristics of electrophysiological examination of anterior-type atrioventricular reentry tachycardia:

1 induced atrial premature stimulation of OAVRT without SR-like leap-type prolongation (except for patients with dual-lumen with atrioventricular nodules), as long as the critical extension of SR makes the impulse reach the ventricular end of the bypass, the latter has been separated from the adverse effect. In the expected period, a foldback can be formed.

2 paroxysmal OAVRT attack frequency: ST-T or T wave can be seen on the retrograde P' wave, RP-< P--R, indicating that the chamber conduction is faster than the atrioventricular conduction, in the esophageal lead RP-interval 70ms.

3 The polarity of the P' wave on each lead: it can reflect the position of the bypass attached to the atrium. For example, the bypass of the left free wall has a P' wave on the I, aVL lead, and the side wall is bypassed. The P' wave appears in the II, III, and aVF leads.

4 patients with OAVRT are often accompanied by bypass ipsilateral bundle branch functional block: this is due to the rapid conduction of the chamber, the reentry cycle is shorter than the effective refractory period of the ipsilateral bundle branch, so the impulse to retrograde to the atria must be bypassed. Down to the contralateral bundle branch, can reach the ventricle end of the bypass, resulting in prolonged return loop, increased return time, slow heart rate, extended RP-interval, bypass bundle beam conduction block, VA The period is longer than 25ms when there is no block.

5 atrial premature contraction stimulation can be terminated by OAVRT: because the atrium is part of the reentry loop, timely atrial contraction stimulation can block the reentry.

6 tachycardia episodes: often accompanied by QRS wave alternation and/or alternating cardiac cycle length, this narrow QRS tachycardia with QRS electrical alternation is highly specific for determining OAVRT (96%).

7 eccentric reverse atrial activation sequence: the earliest atrial depolarization occurred in the atrium near the bypass, the eccentric reverse atrial activation sequence, the earliest atrial arousal A wave was recorded as the bypass right atrial appendage, followed by the His bundle The A wave was recorded, and finally the A wave was recorded for the coronary sinus. When the room was reversed, the atrial activation was eccentric. If the atrial activation recorded by the distal electrode of the coronary sinus was the highest, the bypass was on the left side; The atrial activation recorded by the right atrium electrode is the most advanced, and the bypass is in the right free wall. When the interval is bypassed, the atrial activation of the chamber is normal, that is, the atrial wave of the Hist beam is the highest.

(2) Electrophysiological examination features of retrograde atrioventricular reentry tachycardia:

1 ventricular activation is eccentric: QRS wave morphology and atrial pacing lead to the same magnitude of QRS when maximal pre-excitation.

2 Atrial and ventricular waves are 1:1 conduction.

3 ventricular premature stimulation can not terminate the tachycardia when the Heric bundle or atrium can not be activated.

4 Atrial pacing and tachycardia when the atrial activation sequence is the same.

5 When the critical distance between the general single bypass and the normal atrioventricular conduction system is above 4 cm: the retrograde reentry tachycardia is easy to form.

6 Reverse atrial sequence: Asymmetry is transmitted symmetrically from the atrioventricular node to the right and left atrium.

7 typical retrograde type atrioventricular reentry tachycardia: His bundle always depolarizes first, and then continue to reverse the atrial agitation, so the H wave is always before the A wave.

8 tachycardia can be induced by an appropriate pre-term electrical stimulation: it can also be terminated by a pre-term electrical stimulation.

9 Like OAVRT: AAVRT can usually also be terminated due to atrioventricular block.

The electrophysiological basis of 10AAVRT is that the effective refractory period of the bypass and the effective refractory period of the retrograde transmission of the atrioventricular conduction system are relatively short, and the timely contraction of the pre-systolic contraction in the atrioventricular system causes the occurrence of AAVRT.

(3) Characteristics of multiple atrioventricular bypass reentry tachycardia electrophysiological examination:

1 Foldback between bypass and bypass: First, check the existence of composite bypass, except for atrioventricular nodal conduction and Mahaim pre-excited junction conduction through right atrial programmable scanning and His bundle pacing, followed by Stimulation of different frequencies and parts to clarify the location and refractory period of the bypass provides a clear basis for the diagnosis and treatment of multiple atrioventricular bypass.

Foldback between 2Kent bundle and Mahaim bundle: If Kent bundle is used for cis-ventricular conduction, and Mahaim bundle is used for reverse chamber conduction, His's beam diagram can trace the excitation sequence of Ae-Ve-Ae-Ve, VA There is no H wave. When the excitation is reversed along the Mahaim beam, the ventricular excitation wave V can bypass the His bundle and return to the atria. When the His bundle pacing occurs, the wave appears, which can prove the existence of the Mahaim bundle, the atrioventricular node and the ventricle. When the Mahaim bundle between the muscles is used for the junction reentry, the His bundle beam diagram can only trace Ve-Ve-Ve, without He, but the A wave and Ve are separated.

End of 3Mahaim bundle or reentry between nodular bypass and bundle bypass: the end of the Mahaim bundle or the atrioventricular conduction of the ventricular bundle passes through the atrioventricular node, and the AH gradually prolongs during program pacing; the bundle bypass itself may have Incremental performance, the lower atrial stimulation makes full pre-excitation, showing that the right bundle branch potential precedes HB.

Diagnosis and diagnosis of atrioventricular reentry tachycardia

Diagnostic criteria

1. Diagnosis of anterior-type atrioventricular reentry tachycardia

(1) ECG characteristics:

1 timely atrial premature contraction (or ventricular premature contraction) spontaneous or electrical stimulation can induce and terminate the seizure;

2 frequency is 150 ~ 240 times / min, mostly around 200 times / min, 38% of patients can appear QRS electrical alternation;

The 3P-wave always appears after the QRS wave, RP-/R<1, P-II, P-III, P-aVF inversion, RP-interval 70ms;

4 induced initial non-proliferative PR interval prolongation;

5P-EP-V1 30ms;

6 visible functional bundle branch block;

7 without accompanying atrioventricular block.

(2) Atrioventricular reentry tachycardia with atrioventricular node double path is the most common, the frequency of AVRT is more than 180 times / min, if 150 times / min should pay attention to:

1 room has a double path, and AVRT passes through the atrioventricular node and passes slowly;

2 should exclude the role of drugs, such as verapamil, propafenone, propranolol, etc. have an inhibitory effect on the atrioventricular node, can slow down its conduction, the frequency of AVRT is also slow, according to the medical history during the examination, medication And electrocardiogram, electrophysiological characteristics can make a more accurate diagnosis and differential diagnosis.

2. The diagnosis of retrograde atrioventricular reentry tachycardia is based on the clinical manifestations of the onset, the characteristics of electrocardiogram and the characteristics of cardiac electrophysiological examination to make a correct diagnosis.

Differential diagnosis

1. The differential diagnosis of anterior-type atrioventricular reentry tachycardia is mainly distinguished from atrioventricular nodal reentry tachycardia. The main points of identification are:

(1) The P--R interval of the first heart beat of tachycardia is prolonged in AVNRT, but not extended in OAVRT.

(2) The P wave of AVNRT mostly overlaps with QRS wave, 2/3 patients can't see P-wave, only 33% of patients can see P-wave, its RP-interval is <70ms, and the P-wave of AVRT is almost 100% visible. To, RP-interval 1>70ms.

(3) P-wave or QRS wave leakage may occur during AVNRT (conduction block may occur), while the OAVRT chamber relationship is 1:1 conduction, and P-wave or QRS wave leakage and atrioventricular separation may not occur. There is no second degree atrioventricular block.

(4) Esophageal lead ECG shows ventricular activation to atrial first agitation (VA) interval at least 115ms at OAVRT, and usually <60ms at AVNRT, so when VA interval <115ms, OAVRT is not supported, AVNRT The S2R interval jumps 60 ms, the RP-E interval is 70 ms, and the OAVRT is <60 ms and > 70 ms, respectively.

2. The differential diagnosis of retrograde atrioventricular reentry tachycardia and supraventricular tachycardia and bypass as a "bystander" combined with atrial tachycardia or atrioventricular nodal reentry tachycardia.

(1) Identification with ventricular tachycardia: ECG shows that the ventricular premature contraction, or electrocardiogram, intracardiac electrogram and esophageal electrode recording of the atrioventricular septum are favorable for the diagnosis of ventricular tachycardia. .

(2) The QRS may be broadly pre-excited with the bypass as a "bystander" combined with atrial tachycardia or atrioventricular nodal reentry tachycardia, but the bypass is not involved in the tachycardia pathway, and it is atrial. The distinguishing point of tachycardia is that the ventricular premature contraction pacing captures the ventricular ventricular tachycardia and can not terminate the tachycardia. It is difficult to distinguish the atrioventricular nodal pathway. Both the bypass and the dual pathway can participate in the reentry, unless the program is sexual. Pre-systolic or ventricular pre-systolic pre-excited ventricles or atria without terminating tachycardia.

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