Left bundle branch septal branch block

Brief introduction of left bundle branch septal branch block Left bundle branch septal block (LMFB) referred to as septal block block, also known as left septal block block, referred to as septal block block, left septum branch block, etc., also known as forward conduction delay . Symptoms and signs: The left bundle branch septal block itself does not produce significant hemodynamic disorders, so it is often asymptomatic in clinical practice. More manifestations of the symptoms and signs of the primary disease. basic knowledge The proportion of illness: 0.0021% Susceptible people: no specific population Mode of infection: non-infectious Complications: high blood pressure

Left bundle branch septal block blockage

(1) Causes of the disease

The occurrence of septal branch block in the left bundle branch suggests organic heart disease. Ischemic heart disease such as coronary heart disease is the most common cause of septal block, especially in patients with diabetes and hypertension. Arterial anterior descending artery occlusion may be the most common cause of septal block, and some people believe that this is a chronic progressive process of unknown cause, left bundle branch septal branch lesions, such as ischemia, injury, degeneration, Fibrosis and other prone to block, can also be seen in myocarditis, cardiomyopathy, emphysema, papillary muscle dysfunction, etc., septal branch block is the most common one of the three branches of the left bundle branch.

The cause of intermittent septal block: common in ischemic heart disease, diabetes and cardiomyopathy, the pathological basis can be caused by ischemia, tachycardia, trauma and degeneration.

(two) pathogenesis

Left anterior descending coronary artery occlusion may be the most common cause of septal block, and some people believe that this is a chronic progressive process of unknown cause, left bundle branch septal branch lesions, such as ischemia, injury, Degeneration, fibrosis, etc. are prone to blockage.

Left bundle branch septal block block prevention

1. Active treatment of the cause, such as treatment of coronary artery disease, hypertension, pulmonary heart disease, myocarditis, etc. can prevent the occurrence and development of indoor block.

2. Appropriate work and rest, diet and regular living, appropriate participation in physical exercise.

Left bundle branch septal block block complication Complications

Complications such as high blood pressure.

Left bundle branch septal block block symptoms common symptoms palpitations

The left bundle branch septal block itself does not produce obvious hemodynamic disorder, so it is often asymptomatic in clinical practice, and more often manifests as the symptoms and signs of the primary disease.

Left bundle branch septal branch block

The corresponding laboratory test results for the primary disease may change.

Electrocardiogram examination

(1) Characteristics of typical ECG of left bundle branch septal block:

1V1, V2 lead R wave increased, Rv1 or Rv2 Rv6, V2 lead R / S > 1, V3R, V4R lead R / S 1.

2V5, V6, I lead without Q wave, or only small q wave, its amplitude.

The 3QRS motor axis is normal and the QRS time is normal.

4 should be excluded from right ventricular hypertrophy, posterior wall myocardial infarction, type A pre-excitation syndrome, right bundle branch block, etc., the diagnostic criteria for electrocardiogram of the left bundle branch septal block have not been unified.

(2) Left bundle branch septal branch block type:

The type 1A septal block is characterized by:

A. V1 ~ V3 leads appear increased R wave, V2 lead R / S > 1 and / or Rv2 Rv6.

There are no initial q waves in the B.V5 and V6 leads, or q waves <0.1 mV.

C. Excluding right ventricular hypertrophy, right bundle branch block, positive posterior wall myocardial infarction, type A pre-excitation syndrome.

The type 2B septal block is characterized by:

A. V1 ~ V3 leads a small q wave (QR, qR, qRs type), and can appear intermittently.

B. The duration of the attack is equal to the PR of the intermittent period.

C. Excluding intermittent pre-excitation syndrome, intermittent left bundle branch block, if abnormal electrocardiogram V1 ~ V3 lead abnormal q wave, and V5, V6, I lead no small q wave, combined with clinical exclusion of anterior wall myocardial infarction , right ventricular hypertrophy, acute pulmonary infarction, pre-excitation syndrome, may be prompted for type B septal block.

(3) Special type of left bundle branch septal block: There are two different types of left bundle branch septal block: one is more persistent: the QRS initial vector is leftward, and the forward vector is significantly increased. , ECG right chest lead R / S > 1.0; the other is intermittent seizures (ie paroxysmal episodes): the initial vector of QRS backwards, the abnormal Q wave appeared in the right chest lead.

Diagnosis of intermittent septal block:

1 In the same frame electrocardiogram, intermittent abnormal Q wave or QS wave appears in the right chest lead (V5R ~ V3).

2 The interval between the attack and the intermittent period is equal, and the power axis is similar.

3 Intermittent left anterior branch block, bundle branch block and pre-excitation syndrome (especially Mahaim type) and other intermittent indoor conduction disorders (except in combination) must be excluded because they can also lead to the right chest lead Abnormal Q waves or QS waves occur intermittently, but the mechanism is not the same.

2. Characteristics of ECG vector diagram

(1) The left bundle branch septal block ECG vector diagram shows that the transverse plane is more obvious, the QRS loop initial vector is leftward, the rightward vector disappears or decreases significantly, and the ring body shifts obviously forward.

(2) The maximum vector angle of the QRS ring is >30°, and the area of the QRS ring in front is more than 2/3 of the total area.

(3) The QRS ring maximum vector angle > 45 ° can be clearly diagnosed.

(4) should exclude right ventricular hypertrophy, positive posterior wall myocardial infarction, type A pre-excitation syndrome, right bundle branch block and so on.

Diagnosis and differentiation of left bundle branch septal block

Left bundle branch septal block, QRS ring forward, R wave appears in right chest lead, according to the performance of ECG and ECG vector can be considered, but these manifestations can also occur in other diseases, so in the identification When diagnosing, not only rely on ECG, ECG vector map, but also should be combined with medical history, physical examination, echocardiography and X-ray examination for comprehensive analysis.

Differential diagnosis

1. Identification of incomplete left bundle branch block: Incomplete left bundle branch block, there may be disappearance of the initial Q wave in the I, V5, V6 leads, similar to the septal branch block, but Incomplete left bundle branch block ECG vector diagram often shows the entire QRS ring, especially in the middle of the slow running characteristics; ECG V5, V6 lead QRS wave peak, often can be blunt or notched, and septum The branch block has no such changes.

2. Identification of right ventricular hypertrophy: R wave of V1 lead in right ventricular hypertrophy is increased, the normal initial vector from left to right usually exists, that is, standard lead I and V5, V6 lead has normal starting q wave, Moreover, the electrocardiogram shows right ventricular hypertrophy, which often indicates that the degree of hypertrophy is quite obvious, so the cause of right ventricular hypertrophy can be found clinically.

3. Identification of right bundle branch block: When some right bundle branch block, when the centrifugal branch and the centripetal branch shift forward, high R wave can appear on the V1 lead, but according to the right, The existence of the terminal attachments that are slowly running before and the normal left-to-right start vector are not difficult to identify with the septal branch block.

4. Identification of the posterior wall myocardial infarction: the posterior wall refers to the posterior bottom of the left ventricle, which is the last part of the left ventricle. Therefore, the myocardial infarction in this site does not affect the QRS start vector, but the late QRS vector. A change causes the QRS vector to shift forward. On the electrocardiogram, the V1 and V2 leads can produce high R waves, but there is still a normal starting Q wave in the left heart lead, and the septal branch blocks the left heart guide. Union V5, V6 without Q wave.

5. Identification of type A pre-excitation syndrome: In the type A pre-excitation syndrome, the QRS start vector (delta vector) is slow to run, and the QRS loop running time is extended, and the secondary ST vector and T-ring occur. Changes, etc., the ECG appears as a shortened PR interval and the initial pre-shock.

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