FE Arrhythmias & Cardiac Function Flashcards

Which is the most common fetal cardiac arrhythmia encountered in clinical practice?

Answer: Premature atrial contractions (PACs)

Premature atrial contractions (PACs) are the most common fetal arrhythmia, usually benign and resolving spontaneously.

Most premature atrial contractions (PACs) in the fetus are:

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.

Fetal supraventricular tachycardia (SVT) is defined by a ventricular rate of:

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.

Which M-mode echocardiographic finding is most useful for diagnosing fetal tachyarrhythmias?

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.

Untreated sustained fetal SVT is most likely to lead to which complication?

Answer: Non-immune hydrops fetalis

Sustained SVT can cause high-output heart failure, leading to non-immune hydrops fetalis if untreated.

Which antiarrhythmic drug is most commonly used as first-line transplacental therapy for fetal SVT?

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.