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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 .
The left bundle branch block can be further sub classified into: Left anterior fascicular block. In this case only the anterior half of the left bundle branch (fascicle) is involved; Left posterior fascicular block. Only the posterior part of the left bundle branch is involved; Other classifications of bundle branch blocks are; Bifascicular ...
Normal variation causing LAD is an age-related physiologic change. Conduction defects such as left bundle branch block or left anterior fascicular block can cause LAD on the ECG. Pre-excitation syndrome as well as congenital heart diseases such as atrial septal defect, endocardial cushion defects can also cause LAD on ECG.
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 contracts first . The signal then spreads from the purkinje fibers of the left ventricle over ...
There are two branches of the bundle of His: the left bundle branch and the right bundle branch, both of which are located along the interventricular septum. The left bundle branch further divides into the left anterior fascicle and the left posterior fascicle. These structures lead to a network of thin filaments known as Purkinje fibers.
Left anterior fascicular block (LAFB) is an abnormal condition of the left ventricle of the heart, [1] [2] related to, but distinguished from, left bundle branch block (LBBB). It is caused by only the left anterior fascicle – one half of the left bundle branch being defective. It is manifested on the ECG by left axis deviation.
When left bundle-branch block (LBBB) is accompanied by right axis deviation (RAD), the rare combination is considered to be highly suggestive of dilated or congestive cardiomyopathy. [29] [30] Echocardiogram shows left ventricular dilatation with normal or thinned walls and reduced ejection fraction.
Pharmacologic agents such as adenosine, regadenoson (Lexiscan), or dipyridamole is generally used when a patient cannot achieve adequate work level with treadmill exercise, or has poorly controlled hypertension or left bundle branch block. However, an exercise stress test may provide more information about exercise tolerance than a ...