Language
Country/Area
No result found
The Secret of Heart Electricity: How Bundle Branch Block Changes Heart Rhythm
Inside our hearts is a sophisticated electrical system that controls the beat and rhythm of our hearts. When a bundle branch becomes blocked, this not only changes the flow of electricity in the heart, but can also affect the health of the entire body.
Anatomy and Physiology
The heart's electrical activity begins at the sinoatrial node, a natural pacemaker located above the right atrium. The electrical impulse travels through the left and right atria and converges at the atrioventricular node. From the AV node, the electrical impulse travels down the bundle of His and divides into the left and right bundle branches.
The right bundle branch has only one fascicle, while the left bundle branch is divided into two fascicles: the left anterior fascicle and the left posterior fascicle.
The fascicles eventually resolve into millions of Purkinje fibers, which intersect with the myocardial tissue, allowing rapid and coordinated physiological depolarization of the ventricles.
Mechanism
When a bundle branch or fascicle is damaged (for example, due to heart disease, myocardial infarction, or after heart surgery), it may not conduct electrical impulses properly. This causes the path of ventricular depolarization to change, and the electrical impulse may move through the muscle fibers, which not only delays the transmission of the electrical impulse but also changes its direction of propagation.
Ultimately, this leads to ventricular desynchronization, prolonged ventricular depolarization, and possibly a decrease in cardiac output.
In cases of heart failure, a specialized pacemaker may be used to re-coordinate the action of the heart's ventricles.
Diagnosis
Bundle branch block is usually diagnosed by electrocardiogram (ECG). When the duration of the QRS complex exceeds 120 milliseconds, it can be diagnosed as bundle branch block. Right bundle branch block typically prolongs the second half of the QRS complex and may slightly shift the heart's electrical axis to the right.
Left bundle branch block widens the overall QRS complex and shifts the heart's electrical axis to the left.
In addition, an EKG with bundle branch block will show appropriate T wave deviation, meaning that the T wave is opposite to the terminal deflection of the QRS complex.
Type
Based on the anatomical location of the bundle branch block, bundle branch blocks can be further classified as:
- Right bundle branch block, either incomplete (IRBBB) or complete (CRBBB)
- Left bundle branch block, either incomplete (iLBBB) or complete (cLBBB)
TreatmentLeft bundle branch block can be further divided into left anterior bundle branch block and left posterior bundle branch block.
Some people are born with bundle branch block, while many acquire the condition as a result of heart disease. While some people may perform normally on exercise and have only abnormalities on an EKG, if the bundle branch block is associated with significant damage to other parts of the heart, it may suggest internal heart disease.
In more severe cases, a pacemaker may be needed to restore the heart's electrical supply.
These changes in electrical current contain many important signals about heart health. How should we understand and respond to these signals?
