What is a Bifascicular Block?

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  • Written By: Amanda Dean
  • Edited By: Lauren Fritsky
  • Last Modified Date: 29 September 2019
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Bifascicular block is a chronic heart condition where two bundles of vascular tissue that control the heart fail to send the appropriate signal. The heart does not receive adequate electrical impulses, which can result in an irregular heartbeat. Three main fasciculi function within the heart: the right bundle, the left anterior fascicule, and the left posterior fascicule. A bifascicular block combines any two of these pathways.

This condition is a congenital defect that may go undiagnosed for years in some patients, while in other cases, the block is caused by a traumatic cardiac event, such as a heart attack or heart surgery. Some medications are associated with heart blocks, and this disorder is most common among people with other heart problems, like congestive heart failure or myocardial infraction. Vascular conditions, like high blood pressure or blood clots, can contribute to vascular blockage as well.

Also known as bundle branch block, bifascicular block can make it difficult for the heart to pump forcefully enough to efficiently circulate a sufficient amount blood throughout the body. In many cases, it doesn't cause symptoms, although some people may experience dizziness, fainting, chest pain, or shortness of breath. A patient with a block may have a slow or irregular heartbeat.


A bifascicular block is a dangerous medical condition, especially when combined with other heart problems. It can cause the heart to stop beating altogether in a fatal cardiac arrest. Patients with this condition are at a higher risk of mortality during a heart attack than patients with healthy fasciculi. Patients are advised to wear a bracelet or tag that indicates that they have this problem in case of a cardiac emergency.

In cases where healthcare professionals suspect a block, they will order an electrocardiogram. The condition may also be diagnosed incidentally while the medical professional is examining for other heart conditions using this test. This test is typically followed up by an echocardiogram, that allows the healthcare provider to view the motion of the beating heart.

In most cases, the bifascicular block is not treated, but it will be closely monitored. A patient may be treated for associated heart problems, and a medical professional may examine medications taken regularly by the patient and attempt to find alternatives to those that might be exacerbating the effect of the block. If the patient has a history of fainting associated with the problem, he or she may be fitted with a pacemaker to mimic the electrical impulses that the heart is missing.


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Post 3

@SushiChamp – Good observation about the symptoms. I think if you have an illness like this one, it’s important to eat really nutrient-dense food so your blood has as many good things in it as possible. It would also be a good idea to learn to breathe more deeply, since most people are shallow breathers.

In my health-nut opinion, those steps would help alleviate the symptoms a bit, by increasing the amount of oxygen and nutrients in the patient’s blood. In other words, if your “engine” isn’t running smoothly, give it better gas!

Post 2

@kangaBurg – Your comment about inefficient blood flow is spot on. That’s what makes conditions like bifascicular block so scary – as you rightly put it.

I work in a clinic, and this is one of these conditions that still scares me, even after all these years.

It's important to remember that oxygen is also circulated through blood flow, and that’s why some symptoms of this condition resemble those of blood loss, such as dizziness and fainting.

Post 1

That sounds like a really scary health condition. It always fascinates me how our bodies run on electrical impulses, and that even the slightest misfire can cause such serious problems. The heart is a complex organ, and if it’s not “firing on all cylinders”, your body won’t get the nutrients it needs because your blood won’t flow as efficiently as it should.

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