Echocardiogram Network Fundamentals 2 — Questions and Answers
Question 1: Which cardiac structure serves as the primary pacemaker of the heart?
- AV node
- Sinoatrial (SA) node (Correct answer)
- Bundle of His
- Purkinje fibers
Correct answer: Sinoatrial (SA) node
The sinoatrial (SA) node, located in the right atrium, is the heart's primary pacemaker, generating electrical impulses at 60–100 bpm.
Question 2: What is the intrinsic firing rate of the AV node when acting as a secondary pacemaker?
- 60–100 bpm
- 40–60 bpm (Correct answer)
- 20–40 bpm
- 100–150 bpm
Correct answer: 40–60 bpm
The AV node has an intrinsic rate of 40–60 bpm, slower than the SA node, making it a secondary pacemaker.
Question 3: On an echocardiogram, which finding would suggest AV conduction delay affecting mechanical function?
- Prolonged E-wave deceleration time
- Simultaneous atrial and ventricular contraction (Correct answer)
- Increased LVOT velocity
- Reversed E/A ratio
Correct answer: Simultaneous atrial and ventricular contraction
A very long PR interval can cause simultaneous atrial and ventricular contraction, visible on echo as an absent or truncated A-wave.
Question 4: The Bundle of His bifurcates into which two structures?
- SA node and AV node
- Right and left bundle branches (Correct answer)
- Purkinje fibers and papillary muscles
- Moderator band and chordae tendineae
Correct answer: Right and left bundle branches
The Bundle of His divides into the right and left bundle branches, which carry impulses to the ventricular myocardium.
Question 5: In left bundle branch block (LBBB), how does septal motion typically appear on M-mode echocardiography?
- Normal anterior motion in systole
- Paradoxical (posterior) septal motion (Correct answer)
- Absent septal motion
- Hyperdynamic septal motion
Correct answer: Paradoxical (posterior) septal motion
LBBB causes paradoxical posterior septal motion on M-mode due to abnormal electrical activation sequence of the left ventricle.
Question 6: Which echocardiographic Doppler parameter is most directly affected by variations in heart rate?
- Peak aortic velocity
- Mitral E/A ratio (Correct answer)
- Tricuspid annular plane systolic excursion (TAPSE)
- Left ventricular outflow tract diameter
Correct answer: Mitral E/A ratio
The mitral E/A ratio changes with heart rate because faster rates shorten diastolic filling time, reducing the A-wave contribution and altering the E/A ratio.
Question 7: What conduction pathway is responsible for the rapid spread of electrical impulses through the ventricular myocardium?
- Internodal tracts
- Bachmann's bundle
- Purkinje fiber network (Correct answer)
- Coronary sinus
Correct answer: Purkinje fiber network
The Purkinje fiber network enables rapid conduction throughout the ventricular myocardium, ensuring near-simultaneous ventricular contraction.
Echocardiogram Network Fundamentals 2
Which cardiac structure serves as the primary pacemaker of the heart?