week 8 AXIS

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Questions and Answers

What is the characteristic QRS pattern in V1 that indicates a Right Bundle Branch Block (RBBB)?

rSR pattern

What is the significance of a new onset of chest pain and a new RBBB in a patient?

Indicates critical occlusion of the Left Anterior Descending (LAD) artery

What is the difference between a complete RBBB and an incomplete RBBB?

QRS duration is normal in incomplete RBBB

Which cardiac pathology can cause a Right Bundle Branch Block (RBBB)?

Right ventricular hypertrophy Signup and view all the answers

What is the role of the Bundle of His in the normal electrical pathway of the heart?

Transmits the electrical signal from the AV node to the Bundle branches Signup and view all the answers

What is the term for the blockage of all three fascicules below the AV node, resulting in bi-fascicular block plus complete heart block?

Tri-Fascicular Block Signup and view all the answers

What type of block is associated with aortic stenosis, anterior MI, and congenital heart disease?

RBBB + LAFB or RBBB + LPFB Signup and view all the answers

What is the term for the poor progression of the R-Wave in the ECG?

Poor R-Wave Progression Signup and view all the answers

What is the term for the blockage of the left anterior fascicle and the right bundle branch?

Left Anterior Fascicular Block (LAFB) + RBBB Signup and view all the answers

What is the term for the blockage of the left posterior fascicle and the right bundle branch?

Left Posterior Fascicular Block (LPFB) + RBBB Signup and view all the answers

What is the term for the abnormal conduction of the electrical impulse through the ventricles?

Intraventricular Conduction Delay Signup and view all the answers

What are the three stages of ECG changes in Acute Coronary Syndrome?

Ischaemia, Injury, and Infarction Signup and view all the answers

What is the ECG criterion for ST elevation in STEMI in limb leads?

ST elevation of ≥ 1mm in 2 contiguous limb leads Signup and view all the answers

What is the difference between myocardial ischaemia, injury, and infarction?

Ischaemia is reversible, injury is reversible if blood flow is restored, and infarction is irreversible Signup and view all the answers

What is the characteristic of ST elevation in myocardial injury?

Elevation above the isoelectric line, concave down or horizontal shape, and 1 mm or more in limb leads or 2 mm or more in chest leads Signup and view all the answers

What is the term that describes the spectrum of conditions including unstable angina, NSTEMI, and STEMI?

Acute Coronary Syndrome (ACS) Signup and view all the answers

What is the characteristic of T wave inversion in myocardial ischaemia?

Transient and brief, reversible Signup and view all the answers

What is the significance of new LBBB in the ECG criteria for STEMI?

It is a criterion for STEMI, along with clinical symptoms consistent with ACS Signup and view all the answers

What is the difference between ST depression and ST elevation?

ST depression is more commonly associated with ischaemia, while ST elevation is more commonly associated with injury or infarction (STEMI) Signup and view all the answers

Study Notes

Acute Coronary Syndrome (ACS)

A spectrum of conditions including:
- Unstable angina (UA)
- Non-ST elevation myocardial infarction (NSTEMI)
- ST elevation myocardial infarction (STEMI)
All have similar presentations, generally from plaque rupture and platelet aggregations, microcirculation/spasm
The only difference is the degree of obstruction

ECG Criteria for STEMI

Clinical symptoms consistent with ACS with ECG features including:
- ST elevation of ≥ 1mm in 2 contiguous limb leads
- ST elevation of ≥ 2mm in 2 contiguous chest leads
- New LBBB
- Evolution of ECG changes

Ischaemia, Injury, & Infarction

Myocardial ischaemia: imbalance between myocardial oxygen supply and demand
Ischaemia can progress to:
- Injury: ST segment elevation, cells stop functioning properly, still reversible
- Infarction: abnormal Q wave, not reversible

Myocardial Ischaemia

T wave inversion
ST depression
Transient and brief, reversible

Myocardial Injury

Hyperacute T waves
Followed by ST elevation
1 mm or more in limb leads, 2 mm or more in chest leads
Two or more contiguous leads, within minutes, reversible

ST Elevation

Look for:
- Elevation above the isoelectric line
- Shape (concave up normal, concave down/horizontal abnormal)
ST depression more commonly associated with ischaemia
ST elevation more commonly associated with injury/infarction (STEMI)

Bundle Branch Blocks

Right Bundle Branch Block (RBBB):
- Wide QRS due to delay in conduction
- Look at V1 and V6
- If QRS V1 is predominantly positive with an rSR pattern, you have a RBBB
- V6 often has a W pattern
Causes of RBBB:
- Right ventricular hypertrophy
- Pulmonary embolism
- Ischemic heart disease
- Rheumatic heart disease
- Congenital heart defects
- Myocarditis
- Cardiomyopathy
Incomplete RBBB:
- If rSR pattern is present in V1 but QRS is normal, you have an incomplete RBBB

Bi-Fascicular and Tri-Fascicular Block

Bi-Fascicular Block: RBBB + LAFB or RBBB + LPFB
Tri-Fascicular Block: involves all three fascicules below the AV node, resulting in bi-fascicular block PLUS complete heart block

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Description

This quiz covers acute coronary syndrome, including unstable angina, NSTEMI, and STEMI, as well as coronary arteries and 12-lead ECG. Learn about the similarities and differences between these heart conditions.