21 Questions
What is Tri-Fascicular Block and what is the resulting heart block?
Tri-Fascicular Block involves all three fascicles below the AV node, resulting in complete heart block.
What are the two possible additional characteristics of Tri-Fascicular Block?
Either LAFB or LPFB.
What are some causes of Tri-Fascicular Block?
Causes include ischemic heart disease, structural heart disease, aortic stenosis, anterior myocardial infarction, congenital heart disease, hyperkalemia, and digoxin toxicity.
How does Tri-Fascicular Block differ from Bi-Fascicular Block?
Tri-Fascicular Block involves all three fascicles, whereas Bi-Fascicular Block involves only two fascicles.
What is the significance of the AV node in Tri-Fascicular Block?
The AV node is the location above which the three fascicles are affected in Tri-Fascicular Block.
What is the axis deviation indicated by a negative lead II?
Left axis deviation
What is a possible cause of left axis deviation?
Left ventricular hypertrophy, inferior myocardial infarction, Wolff-Parkinson-White (WPW) syndrome, or ventricular pacing
What is the significance of the R-wave in an ECG?
It signifies the beginning of ventricular depolarization
What is R-wave progression?
The electrical depolarization of the ventricles being seen from lead V1 to V6
In normal R-wave progression, what is the pattern of the R-wave in leads V1-V2?
Negative
What is the pattern of the R-wave in leads V3-V4 in normal R-wave progression?
Biphasic
What is the pattern of the R-wave in leads V5-V6 in normal R-wave progression?
Positive
What are some causes of extreme axis deviation?
Ventricular rhythms and hyperkalemia
What is the common cause of Left Anterior Fascicular Block (LAFB) and Left Posterior Fascicular Block (LPFB)?
Hyperkalemia
What is Bi-Fascicular Block?
Involves two of the three fascicles, either RBBB + LAFB or RBBB + LPFB
What is a common cause of Left Posterior Fascicular Block (LPFB)?
Ischemic heart disease
What is a common cause of poor R-Wave progression in an ECG?
Right ventricular hypertrophy or cardiomyopathy.
What is the term for an incomplete RBBB when the rSR' pattern is present in V1 but the QRS is normal?
Incomplete RBBB
What is the term for a blockage of the left anterior descending coronary artery, which can cause an LBBB?
LAD occlusion
Causes of Poor R-Wave Progression
Myocardial infarction Cardiomyopathy Right and left ventricular hypertrophy Bundle branch blocks
Left Anterior Fascicular Block (LAFB) Characterized
Characterized by LAD, a negative rS complex in inferior leads, a positive qS complex in lateral leads, and increased QRS voltage in limb leads
Study Notes
Causes of Fascicular Blocks
- Causes of Left Anterior Fascicular Block (LAFB) include myocardial infarction, coronary artery disease, left ventricular hypertrophy, dilated cardiomyopathy, hypertrophic cardiomyopathy, degenerative disease, hypertension, hyperkalemia, myocarditis, and amyloidosis.
- Causes of Left Posterior Fascicular Block (LPFB) include ischemic heart disease, hyperkalemia, myocarditis, and cor pulmonale.
Characterization of Fascicular Blocks
- LAFB is characterized by RAD, a negative rS complex in lateral leads, a positive qS complex in inferior leads, and increased QRS voltage in limb leads.
- LPFB is characterized by RAD, a negative rS complex in inferior leads, a positive qS complex in lateral leads, and increased QRS voltage in limb leads.
Bi-Fascicular and Tri-Fascicular Blocks
- Bi-Fascicular Block involves two of the three fascicles, either RBBB + LAFB or RBBB + LPFB.
- Tri-Fascicular Block involves all three fascicles below the AV node, resulting in complete heart block plus RBBB and either LAFB or LPFB.
- Causes of Bi-Fascicular and Tri-Fascicular Blocks include ischemic heart disease, structural heart disease, aortic stenosis, anterior myocardial infarction, congenital heart disease, hyperkalemia, and digoxin toxicity.
Causes of Left Axis Deviation
- Causes of Left Axis Deviation include left ventricular hypertrophy, inferior myocardial infarction, Wolff-Parkinson-White (WPW) syndrome, ventricular pacing, ventricular rhythms, and hyperkalemia.
R-Wave Progression
- R-Wave Progression is the electrical depolarization of the ventricles being seen from lead V1 to V6.
- In normal R-wave progression, the R-wave is negative in V1-V2, becomes biphasic in V3-V4, and then positive in V5-V6.
Causes of Poor R-Wave Progression
- Causes of Poor R-Wave Progression include myocardial infarction, cardiomyopathy, right and left ventricular hypertrophy, bundle branch blocks, and axis deviation.
Bundle Branch Blocks
- Right Bundle Branch Block (RBBB) is characterized by a wide QRS due to a delay in conduction, with a predominantly positive QRS in V1 and a W pattern in V6.
- Causes of RBBB include right ventricular hypertrophy, pulmonary embolism, ischemic heart disease, rheumatic heart disease, congenital heart defects, myocarditis, and cardiomyopathy.
- Incomplete RBBB is characterized by the presence of an rSR' pattern in V1 but a normal QRS.
- Left Bundle Branch Block (LBBB) is characterized by a wide QRS due to a delay in conduction, with a predominantly negative QRS in V1 and a positive M shape in V6.
- Causes of LBBB include dilated cardiomyopathy, aortic stenosis, ischemic heart disease, hypertension, anterior myocardial infarction, hyperkalemia, and digoxin toxicity.
This quiz explores the various causes of Left Anterior Fascicular Block, a condition that affects the heart's electrical conduction system. Learn about the different factors that contribute to LAFB, including myocardial infarction and cardiomyopathy.
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