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A bundle branch block can be diagnosed when the duration of the QRS complex on the ECG exceeds 120 ms. A right bundle branch block typically causes prolongation of the last part of the QRS complex and may shift the heart's electrical axis slightly to the right.
So if the block happens on the right side, it’s referred to as a right bundle branch block. So with this type, the electrical signal starts at the SA node, contracts the atria, moves through the AV node, splits at the bundle of His, and then moves down the left bundle branch but is blocked on the right bundle branch. And so the left ventricle ...
Left bundle branch block (LBBB) is a conduction abnormality in the heart that can be seen on an electrocardiogram (ECG). [1] In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract later than the right ventricle .
A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical conduction system. [1] During a right bundle branch block, the right ventricle is not directly activated by impulses traveling through the right bundle branch. However, the left bundle branch still normally activates the left ventricle.
Infra-Hisian blocks may occur at the left or right bundle branches ("bundle branch block") or the fascicles of the left bundle branch ("fascicular block" or "Hemiblock"). SA and AV node blocks are each divided into three degrees, with second-degree blocks being divided into two types (written either "type I or II" or "type 1 or 2").
Any abnormality of conduction takes longer and causes "widened" QRS complexes. In bundle branch block, there can be an abnormal second upward deflection within the QRS complex. In this case, such a second upward deflection is referred to as R′ (pronounced "R prime"). This would be described as an RSR′ pattern.
Some BBB are permanent and involve a complete bundle blockage while others are dependent on the underlying activity of the heart. [1] For example, certain situations of excessive or reduced heart rate (tachycardia or bradycardia, respectively) can cause a BBB known as a rate-dependent bundle branch block (RDBBB). This manifests in a similar ...
A bundle branch block either LBBB or RBBB, (although RBBB is known to be associated only with S1 split), will produce continuous splitting but the degree of splitting will still vary with respiration. When the pulmonary valve closes before the aortic valve, this is known as a "paradoxically split S 2 ". [6]