Bundle Branch Blocks Flashcards
What are bundle branches?
The bundle branches are pathways in the heart that carry electrical impulses from the bundle of His to the ventricles.
Which ventricle does the right bundle branch conduct impulses to?
The right ventricle
What two fascicles does the left bundle branch split into?
Anterior and posterior fascicles
What is the primary function of bundle branches?
To rapidly conduct electrical impulses to the ventricles, ensuring synchronous contraction.
Which part of the heart does the bundle of His connect to?
The bundle of His connects the atrioventricular (AV) node to the bundle branches.
What is the significance of bundle branch block?
Bundle branch block can indicate underlying heart disease and can affect the timing of ventricular contraction.
Name characteristics of the right bundle branch
It is shorter and conducts impulses to the right ventricle.
What does a left bundle branch block typically indicate?
That there is an underlying issue with the heart’s electrical system, often related to structural heart conditions such as CAD, cardiomyopathy, or valvular disorders
What is the approximate conduction velocity in the bundle branches?
1-2m/s
What is the role of Purkinje fibers?
Purkinje fibers distribute the electrical impulse throughout the ventricles, leading to co-ordinated contraction.
Do the bundle branches have a slower conduction velocity compared to the sinoatrial node?
Yes
What happens during a complete bundle branch block?
One of the bundle branches fails to conduct impulses, leading to delayed or asynchronous ventricular contraction.
What two classifications can bundle branch blocks fit into?
Complete and incomplete
What is the typical ECG finding in a right bundle branch block?
A wide QRS complex and an RSR pattern in V1 and slurred S wave in V6.
What is the effect of bundle branch block on cardiac output?
It can potentially reduce cardiac output due to ineffective ventricular contraction.
Which bundle branch is most susceptible to ischemia?
Left bundle branch
What is the normal range for the QRS duration in a healthy individual?
Less than 0.12 seconds.
Which ECG lead is most commonly used to assess bundle branch blocks?
Lead V1
Can bundle branch blocks can be asymptomatic in some patients?
Yes
What is the primary treatment for symptomatic bundle branch block?
Pacemaker implantation may be required for symptomatic patients.
Which type of bundle branch block always has a pathological cause?
LBBB
What is the primary cause of Bundle Branch Block?
The primary causes include ischemic heart disease, hypertension, and structural heart changes (cardiomyopathy).
What is the typical ECG finding in a right bundle branch block?
Wide QRS complex with an ‘M’ shape in V1 and V2.
How does a left bundle branch block appear on an ECG?
It shows a wide QRS complex and a slurred R wave in leads I, aVL, V5, and V6.
