FE FE Arrhythmias & Cardiac Function 1 — Questions and Answers
Question 1: Which is the most common fetal cardiac arrhythmia encountered in clinical practice?
- Supraventricular tachycardia
- Complete heart block
- Premature atrial contractions (PACs) (Correct answer)
- Ventricular tachycardia
Correct answer: Premature atrial contractions (PACs)
Premature atrial contractions (PACs) are the most common fetal arrhythmia, usually benign and resolving spontaneously.
Question 2: Most premature atrial contractions (PACs) in the fetus are:
- Conducted to the ventricles (Correct answer)
- Blocked and not conducted
- Associated with structural heart disease
- Indicative of complete heart block
Correct answer: Conducted to the ventricles
Most PACs are conducted, producing an early ventricular beat, though some may be blocked depending on timing and AV node refractoriness.
Question 3: Fetal supraventricular tachycardia (SVT) is defined by a ventricular rate of:
- 160–180 bpm
- 180–200 bpm
- Greater than 200 bpm (Correct answer)
- Greater than 220 bpm
Correct answer: Greater than 200 bpm
Fetal SVT is characterized by a sustained ventricular rate greater than 200 bpm, typically 220–280 bpm with 1:1 AV conduction.
Question 4: Which M-mode echocardiographic finding is most useful for diagnosing fetal tachyarrhythmias?
- Measuring chamber dimensions
- Simultaneous recording of atrial and ventricular wall motion to assess AV relationship (Correct answer)
- Measuring aortic root diameter
- Assessing pericardial effusion
Correct answer: Simultaneous recording of atrial and ventricular wall motion to assess AV relationship
M-mode recording of simultaneous atrial and ventricular wall motion allows assessment of the AV relationship, essential for classifying tachyarrhythmias.
Question 5: Untreated sustained fetal SVT is most likely to lead to which complication?
- Premature delivery
- Non-immune hydrops fetalis (Correct answer)
- Placental abruption
- Oligohydramnios
Correct answer: Non-immune hydrops fetalis
Sustained SVT can cause high-output heart failure, leading to non-immune hydrops fetalis if untreated.
Question 6: Which antiarrhythmic drug is most commonly used as first-line transplacental therapy for fetal SVT?
- Amiodarone
- Flecainide
- Digoxin (Correct answer)
- Sotalol
Correct answer: Digoxin
Digoxin is the traditional first-line transplacental agent for fetal SVT, though flecainide and sotalol are also used for refractory or hydrops cases.
FE FE Arrhythmias & Cardiac Function 1
Which is the most common fetal cardiac arrhythmia encountered in clinical practice?