SHA24/086001

Dr Merna Atiyah Consultant Pediatric & Fetal Cardiology Prince Sultan Cardiac Center, Riyadh Prince Sultan Military Medical City

Cardiac Rhythm in Developing Embryo

Cardiac Rhythm in Developing Embryo • The myocardium begins to contract rhythmically: • 3 weeks post-conception • 6 weeks post-conception AV synchrony can be demonstrated using standard Doppler techniques •

Kamino K, Localization of pacemaking activity in early embryonic heart monitored using voltage-sensitive dye. Nature 1981

•

Viragh S, Challice CE. The development of the conduction system

110 5-6 weeks 170 bpm by 9–10 weeks.

150 bpm by 14 weeks 20 weeks is 140 bpm 130 bpm by term.

fetal cardiac arrhythmias • 90% of cases, arrhythmias are brief of little clinical relevance • Less than 10% of referrals for fetal rhythm abnormalities have a sustained tachyarrhythmia or bradyarrhythmia considered to be of clinical significance.

Primary objective of every newly detected fetal rhythm disorder

(1)Arrhythmia mechanism (2) Clarify its impact on the fetal circulation (3) Treatment option

Challenges in fetal arrhythmia detection

Fetal Tachyarrhythmia assessment •Analysis of cardiac rhythm (normal or abnormal) is based on the ability to record atrial and ventricular contractions simultaneously

Fetal Tachyarrhythmia assessment • Fetal echocardiography • widely used tool for diagnosis and followup • Mapping of mechanical events, atrial or ventricular contraction or both by • M-mode, Doppler, Tissue Doppler

M mode assessment • Simultaneous recording of atrial and ventricular wall motion . • The quality of the assessment affected by -Image resolution -Fetal position

A

Case 1

ATRIAL FLUTTER 2:1 AV CONDUCTION

Pulse Doppler • Pulsed Doppler through INFLOW AND OUTFLOW

• Simultaneous Doppler signals from the SVC/AO, MV/AO, PV/PA

SVC/AO

Supraventricular tachycardia V

• AV and VA intervals, and relationship, gives insight into the mechanisms of tachycardia • AV reentry (AVRT) • Short VA tachycardia • 190 – 290 BPM

A

Premature atrial contractions PAC Conducted PACor blocked at the AV node

PAC

Tissue velocity imaging

Fetal electrocardiograms (fECGs) • Based on signal averaging to assess ‘P’ wave morphology • Limitation: -Does not allow beat-to-beat analysis.

-Not Helpful in diagnosing fetal rhythm and conduction anomalies with irregular heart rates.

- Nii M, Heart 2006

Fetal Magnetocardiograms (fMCGs) • Records the magnetic field created by the electrical activity of the fetal heart with generation of waveforms that are very similar to those observed by ECG ( PQRS complex waveforms) • Limitations : • Need for a magnetically shielded room • Lack of availability of the technology in many centers.

• •

Taylor MJ, Br J Obstet Gynaecol 2003 Menendez T, Am J Cardiol 2001

Current Opinion in Pediatrics 2008

Fetal Magnetocardiography

Definition of Fetal Tachycardia • V rate >180 bpm • Intermittent or sustained • • • •

Common: Supraventricular Tachycardia 66-90% Atrial Flutter 10-30% Sinus tachycardia, ventricular tachycardia and atrial fibrillation.

Management • Urgent cardiac and obstetric evaluation.

• There are three approaches to management: • (1) no intervention but close monitoring • (2) antiarrhythmic drug therapy • (3) delivery.

Management • The choice between immediate delivery or drug therapy should be a balanced • Gestational age • Lung maturity • Circulatory changes present in the fetus • Neonatal facilities for postnatal management

Case 1

Case 1 • Intermittent tachycardia and no signs of haemodynamic impairment, such as AV valve regurgitation and cardiomegaly. • Close monitoring • Deliver the fetus at the appropriate time.

Lisa K Hornberger, Heart, 2007

Management • Delivery with postnatal therapy • Persistent SVT/AF >37 weeks • Fetal drug therapy • SVT/AF <37 weeks (+/- Hydrops) • Direct fetal drug therapy • Poorly tolerated SVT/AF • No response to transplacental pharmacological therapy

Antiarrhythmic drugs

NO CONSENSES

Management â&#x20AC;˘ Based on retrospective studies, several agents are considered effective and relatively safe. Among these, digoxin, flecainide, sotalol and amiodarone

â&#x20AC;˘ Direct fetal administration of adenosine, digoxin and amiodarone has also been attempted

RESULTS

CONCLUSION • Sotalol was associated with the highest rate of prenatal AF termination.

• Flecainide and digoxin : • Higher rates of conversion of SVT to a normal rhythm and with greater slowing of persistent tachycardia than sotalol.

CONCLUSION -First-line flecainide or digoxin considered first to treat significant fetal tachyarrhythmia.

No serious fetal and maternal drug-mediated adverse events observed suggesting that all three agents are relatively safe

CONCLUSION -Fetal hydrops : One third of all AVRT fetuses hydropic compared with 6% with AET/PJRT and 13% with AF..

-Arrhythmia-related mortality was 0% without fetal hydrops but 17% with fetal hydrops

â&#x20AC;˘ AF and SVT had an 8% to 15% recurrence rate on maintenance treatment.

â&#x20AC;˘ weekly assessment of the fetal heart rate until delivery once the arrhythmia appears to be controlled.

Case 2

Supraventricular tachycardia V

A

• AV reentry (AVRT) • Short VA tachycardia • 190 – 290 BPM

• Dx Fetal SVT (Short VA tachycardia) • Started on Sotalol 80mg BID converted to sinus after 3 days

Case 3

COMPLICATION • Fetal hydrops mortality rate • 35% compared with 0% to 4% nonhydropic fetuses.

• The risk of fetal hydrops increases if the arrhythmia presents at a younger gestational age

Conclusion • Therapy for persistent tachyarrhythmias should be started promptly.

• ONLY with mature lung development will be delivered early (>37 weeks)

• Transplacental therapy is the preferred route and is often effective to treat or prevent heart failure.

• Flecainide, digoxin and sotalol are commonly used