Bundle Branch Block

Bundle branch block is a disease affecting the cardiovascular system in which the electrical conduction system of the heart is affected due to the block in the bundle branches. Transmission of the electrical impulses from the atrium to the ventricles regulates the contraction of the muscles of the heart.

The sinoatrial node (SA node) is the primary site of the generation of electrical impulses which then travel through the atria, the atrioventricular (AV) node, and then to the bundle of His, which divides into the left and right bundle branches. These branches transmit electrical impulses to the ventricles, which signals to contract and pump blood out of the heart.

Block in the bundle branches delays or stop the electrical impulses passing through them affecting the normal functioning of the heart. The bundle branch block can be of two types.

• The right bundle branch block occurs when there is a block of electrical impulses in the right bundle branch.

• The left bundle branch block occurs when there is a block of electrical impulses in the left bundle branch.

Various factors lead to the development of the condition. The patient presents with palpitations, difficulty in breathing, weakness, and dizziness.

Early diagnosis and treatment are very important as it is a life-threatening condition. It is diagnosed by the changes seen on the electrocardiogram. Treatment depends on the severity of the symptoms. Regular follow-up is important for these patients.

Bundle Branch Block: Causes

Various factors play an important role in the development of the bundle branch block. The important causes of the bundle branch block include −

• People with various heart diseases such as coronary artery disease, heart attack, heart valve disease, and cardiomyopathy which can damage the muscles of the heart and can affect the electrical conduction system.

• Chronic high blood pressure makes the heart muscle hypertrophied and makes less flexible in turn affecting the electrical signals.

• People with structural abnormalities in the heart present at birth (congenital abnormalities of the heart) can affect the electrical conduction system.

• Patients with lung diseases such as pulmonary hypertension in cases of COPD, and acute pulmonary embolism are prone to develop

• Genetic conditions of the heart which are seen in the families such as Brugada syndrome and Lenègre's disease, can cause abnormalities in the heart's electrical conduction system

• Previous heart surgeries such as bypass, and valve replacement can also damage the heart's electrical conduction system

• Certain medications such as beta-blockers, calcium channel blockers, and antiarrhythmic drugs, can also affect the heart's electrical conduction system

Bundle Branch Block: Symptoms

Symptoms of the patient vary based on the severity of the block. Some patients may present with no symptoms in the beginning or with symptoms of the underlying causes. The main symptoms include −

• The sensation of own heartbeat, the feeling of a rapid, fluttering, or pounding heart.

• Because of the reduced blood flow, patients can present with weakness and fatigue

• Difficulty in breathing especially after physical activities hence affect the daily work

• Chest pain or tightness in the chest or discomfort in the chest can be present

• Nausea, vomiting

• Abnormal heart rhythm

• In patients with extensive block, sudden loss of consciousness is usually temporary loss of consciousness due to a lack of blood flow to the brain

• If the heart is not functioning properly, it can cause fluid buildup in the legs, ankles, and feet

Bundle Branch Block: Risk Factors

The important risk factors of bundle branch block include −

• Older age group people are at increased risk because of the age-related changes affecting the functioning of the heart

• People with a family history of bundle branch block or other heart conditions are at increased risk

• People with a history of heart diseases like coronary artery disease, heart attack, or heart failure, and any congenital abnormalities of the heart and cardiomyopathy due to the damage or weakness of the heart muscles affecting the conduction

• People with chronic high blood pressure as high-pressure damage the arteries and blood vessels in the heart, which can disrupt the normal conduction of electrical impulses through the heart

• People with diabetes mellitus

• Patients on medications such as beta-blockers or calcium channel blockers, can affect the conduction of electrical impulses

• Smoking can damage the arteries and blood vessels in the heart, which can disrupt the normal flow of electrical impulses through the heart

Bundle Branch Block: Diagnosis

The diagnosis of the bundle branch block is based on the ECG and some other diagnostic tests are required to find out the underlying causes

• Electrocardiogram − It is the basic test required to look for the bundle branch block, which measures the electrical activity of the heart and shows various changes in the ECG when the block is present.

• Echocardiogram − It is an ultrasound test in which sound waves are used to create images of the heart's structure and function. Any structural abnormalities or damage to the heart can be made out on this test.

• Exercise stress test − In this, the person is asked to do a physical activity such as a treadmill while connected to the ECG machine. It helps to identify any abnormalities in the heart's electrical activity during physical activity.

• Holter monitor − It is a portable ECG machine that should be worn for 24 to 48 hours to continuously monitor the heart's electrical activity. It helps to look for any sudden or intermittent changes in the heart's electrical activity that may not be detected during a standard ECG.

• Cardiac MRI − It is used to look for any structural abnormalities or damage to the heart that may be causing the bundle branch block.

• Electrophysiology study helps to identify any abnormalities or blockages in the heart's conduction system.

• Blood tests − To see the levels of certain enzymes and proteins in the blood that can indicate damage to the heart muscle

Bundle Branch Block: Treatment

Treatment depends on the severity of the block. Treatment includes −

• Treat the underlying causes which are the main reason for the bundle bock. Regular follow-ups are advised for these patients.

• Certain medications such as beta-blockers or calcium channel blockers can help to reduce the symptoms, slow the heart rate and improve the heart's electrical activity.

• Some patients may require a Pacemaker to generate the impulses. It helps to regulate the heart's electrical activity.

• Surgery may be required in some patients to replace damaged heart tissue or to correct structural abnormalities that are causing the bundle branch block.

Bundle Branch Block: Prevention

There are no specific methods to prevent the occurrence of the bundle branch block. However, some of the measures that can help to reduce the risk which include −

• Patients with a history of heart disease, blood pressure, and diabetes should be taking treatment to manage the condition which when treated inadequately may lead to bundle branch block.

• Lifestyle changes such as maintaining a healthy body weight, eating a balanced diet, and regular exercises should be done to improve overall health including heart.

• Avoid smoking and managing stress is also important.

Conclusion

Bundle branch block is a medical condition where the electrical activity of the heart is affected because of the various underlying diseases of the heart and other causes. The patient presents with different symptoms depending on the underlying causes.

The diagnosis is primarily done on the characteristic changes shown in the ECG. Necessary treatment in these patients involves medication, a pacemaker, and surgery depending on the severity of the block. Keeping under control of underlying causes, and lifestyle modifications can help to reduce the risk to some extent.