Anterior Left Hemiblock: Causes, Symptoms, Diagnosis and Treatment

It is a condition that occurs when the transfer of impulses from the muscles of the heart is delayed due to a delay in pumping blood.

The left hemiblockes are also called left fascicular blocks, they are a variation in the conduction of the electrical impulse in one of the two auriculoventricular fascicles of the left branch of the bundle of His.

When this anomaly or delay in electrical conduction occurs in the anterior fascicle, it is called left anterior hemiblock.

The presence of the left anterior hemiblock increases with age and is classified as a benign disorder when presented in isolation. Left posterior hemiblock is less common.

The electrocardiographic criteria used for its diagnosis are not very accurate and its clinical significance is more uncertain, and they are associated with blockages of the right branch of the bundle of His.

The left branch of the bundle of His is divided into two, anterior fascicle and posterior fascicle.

The anterior fascicle responsible for transmitting the electrical impulse to the anterosuperior area of ​​the left ventricle and the posterior fascicle responsible for transmitting it to the posteroinferior area.

The difference between the left anterior hemiblock and the left branch block is that the disorder of the latter occurs before the subdivision, and in the fascicular blocks, the alteration is in one of the fascicles only.

Another observable difference in an electrocardiogram, with the left and right branch blocks, is that the hemiblocks do not cause a widening of the QRS complex in the graph.

On the contrary, the main alteration observed in the electrocardiogram when there are fascicular blocks is the presence of a very marked deviation of the cardiac axis to the left of 45 degrees or more.


The left anterior hemiblock is caused by an abnormal functioning of the anterior half of the heart, as a physiological cause, but there are factors that affect left anterior fascicular block. These factors cause the appearance of this anomaly.

Some of the most common causes include:

  • Chronic hypertension
  • Valvular disorders to aortic stenosis.
  • Dilation of the aortic root.
  • Dilated cardiomyopathy.
  • Lung diseases.
  • Degenerative fibrotic disease and aging.
  • Liver diseases.

Symptoms of left anterior hemiblock

In the majority of patients, who suffer from left anterior hemiblock, no symptoms are observed because this condition is asymptomatic, ie it is not related to any specific symptom and the findings are based on the graphic report of the electrocardiogram.

However, when they are associated with another condition, the symptoms are linked to them.

Among the symptoms that usually occur with the occurrence of left anterior fascicular block are the following:

  • Dizziness due to a condition linked to cardiac function.
  • Chest pain that can occur intermittently and recurrently, which is almost always caused by circulatory disorders.

These symptoms are verifiable through the use of a two-dimensional echo.


The diagnosis of this condition is made through the use of 2D echo or auscultation techniques.

A complete cardiac evaluation is essential to know the full extent of left anterior hemiblock.

One of the most important problems related to the diagnosis of left anterior hemiblock, is that they can simulate or hide the electrocardiographic signs of multiple conditions.

As are myocardial infarction or myocardial ischemia and may mask or simulate ventricular hypertrophy, so the evaluation of patients with this condition should be very exhaustive.

Treatment of left anterior hemiblock

The treatment modalities for left anterior hemiblock will depend on the degree of blockage and the severity of the symptoms associated with another disease, to assess the extent of the condition.

Some of the most common protocols for treating left anterior hemiblock include:

  • A diet with a low content of carbohydrates and fats, and alternatively make an increase in protein intake.
  • Administration of oral supplements such as vitamins, fatty acids and omega-3.
  • Replace saturated fats with polyunsaturated fats, such as flaxseed oil or olive oil.
  • Limit the consumption of salt in the diet.
  • Regular exercise such as walking, jogging. A moderate level of physical activities that will depend on the level of tolerance of the patient.
  • Avoid excessive consumption of tobacco and alcohol.