Anterior Left Hemiblock: Causes, Symptoms, Diagnosis and Treatment

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

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

When this anomaly or delay in electrical conduction occurs in the anterior bundle, 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. The left posterior hemiblock is less common.

The electrocardiographic criteria used for its diagnosis are not very accurate. 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 His bundle is divided into two, the anterior fascicle and the posterior fascicle.

The anterior bundle is responsible for transmitting the electrical impulse to the anterosuperior area of ​​the left ventricle, and the posterior fascicle is accountable for sending it to the posteroinferior site.


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

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 abnormal functioning of the anterior half of the heart as a physiological cause. Still, some factors affect the 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 illness and aging.
  • Liver diseases.

Symptoms of left anterior hemiblock

In most patients, who suffer from left anterior hemiblock, no symptoms are observed because this condition is asymptomatic, i.e., it is not related to any specific sign. The findings are based on the graphic report of the electrocardiogram.

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

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

  • Dizziness due to a condition linked to cardiac function.
  • Chest pain can occur intermittently and recurrently, 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 2D echo or auscultation techniques.

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

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

As myocardial infarction or myocardial ischemia may mask or simulate ventricular hypertrophy, the evaluation of patients with this condition should be 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 increase 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 and jogging. A moderate level of physical activity will depend on the patient’s level of tolerance.
  • Avoid excessive consumption of tobacco and alcohol.