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Radiology
Arrhythmias
Built from Obstetric Imaging
What’s inside
6 sections · 86 slides
Overview
- What this topic covers
Recognising a fetal arrhythmia
What counts as abnormal, how common it is, and how you look at it
- When is a fetal heartbeat abnormal?
- Three ways the rhythm goes wrong
- 2%
- Why most of these are not an emergency
- How the fetal rhythm is examined
- The final answer comes after birth
- The three rhythms covered here
Atrial ectopic beats
Extra early beats from the atria: the commonest fetal arrhythmia
- A beat that arrives too early
- 85–90%
- Why the extra beats happen
- Usually isolated, but always check the heart
- Ectopic beats on Doppler and M-mode
- M-mode close-up of a non-conducted extra beat
- The timing pattern that gives it away
- Reading one ectopic beat, step by step
- When extra beats come in a repeating pattern
- Repeating extra beats on umbilical artery Doppler
- Bigeminy: beats arriving in pairs
- “
- What can go wrong
- How these pregnancies are followed
- Treatment before birth
- Delivery and the newborn
- What the referring physician needs to know
Supraventricular tachycardia
A sustained fast rhythm that can push the fetus into heart failure
- A heart that races and will not slow down
- 1–5%
- The short circuit behind it
- Why that loop keeps going
- What else can lie behind it
- Fast rhythm starting and stopping abruptly
- Why a very fast heart fails
- Filling time is the key idea
- 30–50%
- Why hydrops changes everything
- How it comes to attention
- What the ultrasound must show
- Fast rhythm on intracardiac Doppler
- Atrial and ventricular rates matching on M-mode
- Fast rhythm: which one is it?
- Why the two rates differ in flutter
- Very fast atrial rate in atrial flutter
- Deciding whether to treat
- Treat inside the womb, or wait?
- What treatment is aiming for
- First-line drug when there is no hydrops
- Treating a fetus that is already hydropic
- When the usual drugs fail
- Life after birth
- The named syndrome to remember
- What the referring physician needs to know
Complete atrioventricular block
When the atria and the ventricles stop beating together
- When the top and bottom stop talking
- 1 in 20,000
- Where the block comes from
- The structural half
- The autoimmune half
- Which mothers are at risk
- Reading that risk table
- When to watch, and how closely
- Why the outlook is poor
- The three things that make it worse
- How it comes to attention
- What the ultrasound must show
- Slow ventricular rate on umbilical artery Doppler
- Atrial and ventricular rates running apart
- What else to look for on that scan
- “
- Not every block is complete
- Two atrial beats for every ventricular beat
- Counting the beats on intracardiac Doppler
- Managing it before birth
- When to deliver
- Do steroids help?
- After birth: pacing
- What the referring physician needs to know
Pulling it together
A working approach, the key points, and the numbers worth keeping
- A working approach to any fetal rhythm problem
- Key points: atrial ectopic beats
- Key points: supraventricular tachycardia
- Key points: complete AV block
- Key points: what happens to these babies
- Numbers worth keeping
- Further reading suggested by the authors
- References
- References (continued)
- References (continued)
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition