For your heart to beat and function well, the heart’s tissue conducts electrical impulses via the heart muscle in a consistent pattern. This electrical impulse causes the upper chambers (atria) of the heart to contract first and lower chambers (ventricles) to contract subsequently. When any part of this electrical pathway is obstructed, the condition is known as bundle branch block. It is a condition in which there's a delay or blockage along the pathway that electrical impulses travel to make your heartbeat. This makes it harder for the heart to pump blood efficiently throughout the body.

The blockage can happen on the pathway that sends electrical impulses either to the left or the right side of the ventricles of your heart.
Differential diagnosis of wide QRS complex


In most cases, this condition doesn’t show any symptoms and people may have it for years and never realise they have the condition. But, in a few others, a delay in the arrival of electrical impulses to the left ventricle can lead to syncope (fainting) due to infrequent heart rhythms that impact blood pressure. While some people may also experience presyncope that implies feeling like you’re about to faint, but never fainting. Fatigue and shortness of breath are other common symptoms.

Also Read: Heart Valve Disease: Causes, Symptoms And Treatment


Several different heart conditions can cause this problem. For instance, a heart attack can damage heart tissue, which makes it difficult for the heart to conduct electrical impulses. This can result in bundle branch block either at the right or left ventricle.

Other conditions that can cause a bundle branch block include:

Coronary artery disease

Heart failure


Problems with the aortic valve

Heart infection


At times bundle branch block can develop without any underlying heart problem, but it’s most often seen in elderly people.

Also Read: Heart Infections: Causes, Symptoms And Treatment

Risk Factors

Risk factors for bundle branch block include:

This condition is more common in older adults than in younger people.

Any underlying health conditions such as hypertension or other heart diseases can increase the risk of developing bundle branch block.


A person with a right bundle branch block and otherwise healthy, may not need a full assessment. On the other hand, a person with a left bundle branch block will need a complete assessment and the healthcare provider may suggest the following tests:

Electrocardiogram (ECG): This is the test that’s generally used to diagnose any problem with the heart’s electrical impulses. It is a painless test that includes placing leads around the chest that conduct electricity. The leads are connected to wires that sense the electrical impulses to the heart and monitor the heart’s rhythm.

Echocardiogram: An echocardiogram uses sound waves to create images of the heart. This helps doctors to see how efficiently heart and heart valves are working and chambers are pumping. Furthermore, it also measures the thickness of heart muscle and the overall structure of the heart. This test can be beneficial for identifying possible causes of the left bundle branch block.

Additionally, the doctor may suggest certain blood work to monitor lipid profile and other contributing factors for left bundle branch block.


Most people with bundle branch block don’t show any symptoms and don’t require any treatment. But a person with specific symptoms and other heart conditions may need prompt medical care.


A patient with an existing heart condition causing bundle branch block medications is prescribed to reduce high blood pressure and ease symptoms of heart failure.


For a patient with a bundle branch block and a history of syncope, the doctor may recommend placing a pacemaker. It is a compact device implanted under the skin of the upper chest with two wires that connect to the right side of the heart. The pacemaker works to release electrical impulses when required to keep the heart beating properly.

Cardiac resynchronization therapy may be needed for patients with left bundle branch block and low heart-pumping problems. This treatment also involves implanting a pacemaker, but a third wire is connected to the left side of the heart, so that the device can keep both sides working in proper rhythm. This procedure improves the coordination of both lower chambers of the heart, and they contract at the same time.