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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 .
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.
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 fashion to a regular bundle branch block, but occurs only under conditions that affect contractile rate.
Left axis deviation symptoms depend on the underlying cause. [5] For example, if left ventricular hypertrophy is the cause of LAD, symptoms can include shortness of breath, fatigue, chest pain (especially with exercise), palpitations, dizziness, or fainting. [6]
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.
Cardiac involvement is often identified with the presence of conduction system disease (sinus node or atrioventricular node dysfunction) and/or congestive heart failure, including shortness of breath, peripheral edema, syncope, exertional dyspnea, generalized fatigue, or heart block.
[1] [20] One of the most important exams that can be conducted to help determine atrioventricular (AV) conduction block and bundle branch block is an electrocardiogram. Electrocardiograms are used primarily to measure how efficiently the heart is working.
Acute decompensated heart failure (ADHF) is a sudden worsening of the signs and symptoms of heart failure, which typically includes difficulty breathing , leg or feet swelling, and fatigue. [1] ADHF is a common and potentially serious cause of acute respiratory distress. The condition is caused by severe congestion of multiple organs by fluid ...