Fetal Arrhythmia Approach & Guidelines Notes
[Donofrio MT, Moon-Grady AJ, Hornberger LK, Copel JA, Sklansky MS, Abuhamad A, Cuneo BF, Huhta JC, Jonas RA, Krishnan A, Lacey S, Lee W, Michelfelder EC Sr, Rempel GR, Silverman NH, Spray TL, Strasburger JF, Tworetzky W, Rychik J; American Heart Association Adults With Congenital Heart Disease Joint Committee of the Council on Cardiovascular Disease in the Young and Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and Council on Cardiovascular and Stroke Nursing. Diagnosis and treatment of fetal cardiac disease: a scientific statement from the American Heart Association. Circulation. 2014 May 27;129(21):2183-242. doi: 10.1161/01.cir.0000437597.44550.5d. Epub 2014 Apr 24. Erratum in: Circulation. 2014 May 27;129(21):e512. PMID: 24763516.]
FETAL BRADYCARDIA
Sinus/Low atrial Bradycardia
Mechanism
SA node damange
Ion channel dysfx
Suppression of SA node by a 2y source
maternal use of beta-blocker, sedative, other meds
Assoc with L or R atrial isomerism
low atrial rhythm
dual SA node
Usually HR 90-130 bpm
Mangement:
no intervention needed
LQTS and Other Ion Channelopathies
See persistent fetal bradycardia, <3rd%ile for GA is often a presentation for Long QT
Management:
close observation, posntatal EKG for QTc
No treatment needed, unless fetus gets VT/torsades
Avoid maternal hypo-Mg and hypo-Ca especially
Avoid maternal QT prolonging Rx (see www.torsades.org)
Atrial Bigeminy With Block
Blocked Atrial bigeminy with 2:1 conduction pattern --> HR 75-90 bpm
DDx 2nd degree HB
Management:
same as isolated PACs - none needed
Beware of 10% risk of SVT
Weekly fetal HR auscultation by OB/MFM until resolution
Fetal Heart Block
50-55% is from a structural HB, like cc-TGA
40% is from SSA/SSB immune related HB
Ideopathic HB
better Px than other forms
No treatment needed
assoc with channelopathies: NKX2.5, LQT2, SCNA5A mutations (LQT3, Brugada), LQT8
Management:
Some have used beta-agonist (terbutaline, salbutamol, isprenaline) if HR <55 bpm. Reasonable to use if HR >55 but signif CHD is present
Terbutaline is well tolerated by mom, but may note tachy to 120s and ectopy
no known survival benefit
Postnatal EKG warranted- check for long QT, HB, HR...
Auto-immune fetal heart block
[Wainwright B, Bhan R, Trad C, Cohen R, Saxena A, Buyon J, Izmirly P. Autoimmune-mediated congenital heart block. Best Pract Res Clin Obstet Gynaecol. 2020 Apr;64:41-51. doi: 10.1016/j.bpobgyn.2019.09.001. Epub 2019 Oct 8. PMID: 31685414.]
Mechanism in Lupus
anti-SSA (Ro) Ab or anti-SSB (La) Ab passive transfer to fetus
SSA is the major culprit for CHB (complete heart block)
Ab transfer to fetus starts as early as 11 weeks
Epidemiology
Incidence: 1/15,000 to 23,000 live births
If +maternal SSA/SSB, CHB occurs in 2%, but up to 19% if prior child affected if mother has SSA Ab.
if prior affected child had a rash, next child had a 6-10x risk for CHB
Majority of the time mother is ASx/undiagnosed
0.2-0.9% of the population have SSA/SSB antibodies, or higher...
Of SLE patients, 40% have anti-SSA/Ro
Of Sjogren's patients, 60-100% have anti-SSA
Serum levels of SSA/SSB correlate to risk of CHB in child
Cardiac effects:
inflammation
EFE- endocardial fibroelastosis
in 7% of AI related CHB
fetus with EFE --> 51% mortality. if with CM also, then 100% mortality
AV node calcification --> CHB --> fetal HR 50-60bpm instead of 120-160 bpm as is normal
sinus node dysfx/sinus bradycardia, VT, junctional tachy, a-fib, long QT
valve disease
1.6% of cases
See echogenic valve apparatus at 19-22 weeks GA.
May progress postnatally.
High risk of needing surgical intervention.
ventricular dysfx
dilated CM
rare
high mortality rate
11.8% mortality at 7 years old in one report
can be neonatal or late onset DCM
incr risk if hydrops, pericardial effusion, or EFE
Steroids did not mitigate risk for late onset DCM
Heart Block
as early as 16 weeks GA
75% of cases are bn 20-29 weeks GA
1st degree HB does not necessarily predict progression to 3rd degree HB, though cases have been seen with progression
3rd degree HB (CHB) is not reversible
Neonatal Lupus Associated Prognosis:
CHB - mortality 18%
70% die in utero
10 year survival: 86% roughly
Mean delivery at 34-37 weeks gestation
75% by c-section
Need for pacemaker - 70%
Other sx to assess: cytopenia, rash, liver damage, neuropsych xx
rash clears by 8 mo once maternal Ab are gone, rare to leave scar
Fetal risk factors for mortality:
EFE, hydrops, earlier Dx of CHB, lower ventricular rate
2/3 die of severe cardiomyopathy
>50% mortality if EFE present
100% mortality if both EFE and DCM present
Long term risks:
cardiovascular disease in long term
connective tissue disorders
increased risk of infections
Screening
Weekly echo from 16-26 weeks if anti-SSA/Ro Ab present
Looking for 1st degree heart block.
Uncertain value given limited efficacy of intervention/increased stress, and risk that 1st degree can turn into 3rd degree within just one day. Though treating 2nd degree with steroids/IVIG may help.
Possible utility of self monitoring q12 hours with home Doppler monitor
pilot study: 5% false positive rate, 0% false negative...
Intervention
Flourinated steroids = dexamethasone (4 to 8 mg PO daily)
?efficacy
Jaeggi study: dexameth+beta agonist in fetuses with HR<55bpm--> improved 1 year surgical/reduced morbidity
RRNL study - no improvement in survival, progression, or pacemaker timing. In these patients, it was given "shortly after isolated advanced block". Same in other studies...
may prevent progression from 1st/2nd HB to third, may improve EFE and hydrops
Dexamethasone side effects
IUGR
oligo
ductal constriction
maternal DM
CNS side efects
Trial of Dexameth for 1st or 2nd degree HB may be worthwhile, especially if additional cardiac xx (echogenic, regurg, dysfx, effusion)
IVIG + steroids
maybe effective, in that survival was 80% at ~3 years old
Best IVIG timing and repeat dosing interval is unknown
No role for IVIG prophylaxis
IVIG risk- blood product exposure, allergic reaction
Hydroxychloroquine (due to Toll-like receptor inhibition effect)
given to kids off SSA/SSB parents with CHB
no statistically signif difference... low numbers...
RRNL study- may reduce recurrence rate in future pregnancies
In 2nd degree HB, treating with steroids+IVIG may help prevent progression and revert to sinus rhythm
FETAL TACHYCARDIA
If sustained tachy, >50% of the time, treat based on risk profile. Little data to support any particular treatment protocol
rec Rx unless near term, even if no hydrops
if near term--> c/s delivery
If intermittent tachy, >50% of the time, likely only need close observation unless it is VT
rec Rx if there is ventricular dysfx or hydrops
Rare to progress to sustained, but f/u still needed to ensure this is so
VT with rate > 200 bpm --> Rx to prevent rapid progression of hydrops
For all pt, emperic observation postnatally for 2-3 days to see if treatment is needed
Sustained SVT
Usually HR >220 bpm
reentrant SVT and a-flutter, usually
Reentrant SVT
Management
Digoxin is 1st line- PO or IV in most places
Flecainide or Sotolol also used as 1st line in some places
Second line: one of the above or Amio.... ?which is best, though Amio has higher xx for mom
Because hydrops reduces transplacental transfer, c/s direct fetal tx (fetal intramuscular or intracordal injection) if severe hydrops, especially if abnormal biophys profile. Still, it carries risk of fetal demise.
50% of reentrant SVT resolves postnatally
A-flutter
= ~30% of fetal tachy
seen w myocarditis, CHD, SSA/SSB Ab
Management
Sotalol is 1st line- 50-80% effective
Digoxin and Amio also work
Postnatally- trans-esoph pacing or synchronized cardioversion--> sinus rhythm
(be ready to back up pace heart due to SA node suppression...)
Likely won't recur after cardioversion postnatally
Rare Tachyarrhythmias
chaotic or multiofcal atrial tachycardia
last few weeks gestation
seen in Costello syndrome
HR 180-220 bpm, 1:1 conduction
similar to Persitent Junctional Reciprocating Tachy (PJRT), also rare
late 2nd trimester or 3rd trimester
hard to treat
Management
If HR >200 bpm, treat. If HR 160-200 bpm and ventric dysfx, treat.
Digoxin for chaotic/multifocal/atrial ectopic tachy if no hydrops or dysfx. Sotolol/flecainide if hydrops/dysfx
Flecainide for PJRT or rapid atrial ectopic tachy
JET
seen w SSA Ab exposure, both with and without AV block
Flecainide, can also use Amio, but xx...
c/s Dexamethasone if +SSA/SSB
need Rx postnatally usually
If +anti-thyroid Ab- c/s in ddx with atrial ectopic tachy and PJRT
usually no ventric dysfx if this is the cause
Sinus tachy to 180-190 bpm
c/s infection, anemia, Rx exposure, trauma, maternal hyperthyroid
Sustained Ventricular Tachycardia
seen in assoc w AV block, tumors, acute myocarditis, ion chanelopathies
if see both tachy and brady, c/s Long QT
can see torsades, monomorphic VT w ventric dysfx, AV regurg, hydrops w Long QT
Management
Dexameth or IVIG if related to myocarditis or SSA/SSB exposure
Maternal Mg admin if fetal VT >200 bpm, but only for up to 48 hours duration. Ensure maternal Mg is <6 mEq/L before giving a second dose and no maternal toxicity
IV lidocaine, especially if hydrops
PO Porpranolol or mexiletine
If exclude long QT, then can use sotalol, amio, flecainide
No data to determine which Rx is best
Accelerated Ventricular rhythm
just faster than sinus
more benign than VT
seen in late gestation
No Tx needed
IRREGULAR FETAL RHYTHM
Fetal ectopy - 1-3% of all preganncies
Benign
ensure to DDx PAC and PVCs, as wel as 2nd degree HB, LQTS
If frequent PAC- bigeminy, trigeminy, or ore than every 3-5 beats on avg, --> get fetal echo as baseline. If less frequent but it persists more than 1-2 weeks or a question of etiology, then get fetal echo.
PACs 10x more common than PVCs
Ectopy--> risk of SVT/fetal tachy is only 0.5-1%.
couplets, blocked atrial bigeminy increases risk (10% SVT in latter)
Management
no Rx needed
weekly OB ausc of HR check until it resolves is recommended for PAC and PVCs