Fetal

Arrhythmias Dawn Boender, PGY3

Overview

Tachyarrhythmias

Bradyarrhythmias

Fetal Arrhythmias

1% of fetuses

75% extrasystoles

15% tachyarrhythmias

9% bradyarrhythmia

Tachyarrhythmias

Tachyarrhythmia

Differential Diagnosis

Premature Atrial Contractions

Supraventricular Tachycardia

Atrial Flutter

Sinus Tachycardia

Ventricular Tachycardia

Tachyarrhythmia

Making the diagnosis

Brief review…

Tachyarrhythmia

Making the diagnosis

M-mode

Align cursor through one atria and ventricle

Visualizes relationship

Distinguishes type of arrhythmias

Tachyarrhythmia

Making the diagnosis

Pulse wave doppler

Cursor placed between mitral and aortic

valve

Flow disturbances (regurgitation)

Pulse wave doppler

Premature Atrial Contractions

Most common fetal arrhythmia

18-24 wga

Dx: Doppler inflow/outflow or left ventricle

or M-mode

Aggrevating factors

Spontaneous resolution

1% progression to SVT

Premature Atrial Contractions

Premature Atrial Contractions

Premature Atrial Contractions

Management in pregnancy

No treatment needed

Evaluation with fetal echocardiogram

Doppler auscultation q1-4 weeks

F/u US

Resume routine care after 2-3 weeks

Supraventricular Tachycardia

SVT

Most common sustained tachycardia

FHR 240-280 bpm

Accessory pathway vs autonomic

Typically structurally normal

Congenital heart disease up to 5-10%

Dx: 2D, Doppler, M-mode

1:1 conduction

Supraventricular Tachycardia

Supraventricular Tachycardia

Management of Pregnancy

Controversial

D/C precipitating factors

Continuously monitor 8-24 hours

Treat if…

Structurally abnormal heart

>33% present

Hydrops

Controversial: delivery after 32-34wga

Consider vaginal delivery

Supraventricular Tachycardia

Management of Pregnancy

Digoxin

Load with 0.5mg IV q6-8h until:

<25% tachycardia or decreased hydrops

Therapeutic

Toxicity

PO administration BID-QID

Digoxin level, BMP, EKG, cardiologist consult

Second-line agents

Atrial Flutter

Sustained tachycardia

FHR:

Atrial 300-500 bpm

Ventricular <100-300 bpm

Often 2:1 or 3:1 conduction

Structurally normal

Structural heart disease up to 20%

Atrial Flutter

Atrial Flutter

Management in Pregnancy

Digoxin

Sotalol

Propranolol

Sinus Tachycardia

FHR 180-200

1:1 conduction

Causes:

Maternal pyrexia

Stimulants

Maternal thyrotoxicosis

Fetal systemic disease

Anemia, distress, infections

Ventricular Tachycardia

FHR: 180-300 bpm

Not well tolerated

Structural abnormalities, tumors, long QT

NOT a 1:1 ratio

Ventricular Tachycardia

Ventricular Tachycardia

Management in pregnancy

NO DIGOXIN

Oral propranolol, mexiletine, sotalol,

amiodarone

Umbilical vein - lidocaine

Tachyarrhythmia

Outcomes

50% relapse after birth

Medical therapy

Neurological outcomes

Recurrence risk

Bradyarrhythmias

Bradyarrhythmias

Differential diagnosis

Sinus bradycardia

Atrial bradycardia

Blocked atrial bigeminy

Atrial flutter with high-degree block

Complete heart block

Transient responses

Sinus Bradycardia

1:1 conduction ratio

Fetal distress

Long QT syndrome

Risk for ventricular tachycardia

Atrial Bradycardia

Accessory atrial pacemaker

Absent sinus node

Associated with polysplenia

Atrial bigeminy

Atria alternates sinus beats with PACs

PACs during refractory period (AV node)

Ventricular rate

Regular

½ atrial rate

Avoid caffeine, decongestants, tobacco

Atrial Flutter

Atrial rate: 300-500 BPM

High degree AV block

Results in fetal bradycardia

Constant arrhythmia

Treatment: digoxin vs sotalol

Complete Heart Block (CHB)

Most common

FHR: 40-70 bpm

Atrial rate normal

No conduction, resulting in ventricular

rate

May find 1st or 2nd degree block

Incidence: 1/20,000 live births

Complete Heart Block (CHB)

Complete Heart Block (CHB)

Causes

Maternal anti-Ro (SSA) or anti-La (SSB)

antibodies

Associated with SLE, Sjogren’s syndrome, connective tissue disorders

Antibodies damage fetal AV node

Suspected cofactor

20-24wga

Complete Heart Block (CHB)

Causes

Structural heart disease

L-looped ventricles

AV septal defect

Associated with polysplenia

Poor survival outcome

Complete Heart Block (CHB)

Management in pregnancy

Rheumatologic evaluation

CPS, Fetal echo

Doppler of umbilical artery (limited)

Serial growth US

Cardiothoracic ratio

NST not helpful

FHR < 60, up to twice weekly US

Complete Heart Block (CHB)

Management in pregnancy

Dexamethasone

Betamimetic agents

IVIG

Plasmapheresis

In utero heart pacing: experimental

Complete Heart Block (CHB)

Delivery

Cesarean

Consider if hemodynamic compromise

Nonimmune hydrops

Ventricular rate <55bpm

AV valve insufficiency

Pediatric cardiologist and surgeon

available

Outcomes Up to 25% develop nonimmune hydrops

15% survival

CHB with structural abnormality – poor outcome <20% survival

CHB with <55bpm 14% survival

Early delivery for pacemaker 20% survival

Neonatal lupus erythematous in 90% of SSA and SSB

90% survival after neonatal period

Plaquenil – consider in future pregnancies

References Bianci et al. (2010). Tachyarrhythmias in Fetology: Diagnosis and

Management of the Fetal Patient. McGraw Hill Medical. 313-319.

Bianci et al. (2010). Bradyarrhythmias in Fetology: Diagnosis and Management of the Fetal Patient. McGraw Hill Medical. 313-319. 320-327.

Creasy & Resnik (2009). Fetal Cardiac Malformations and Arrhythmias in Maternal Fetal Medicine Principles and Practice, 6th edition. Saunders Elsevier. 336-341.

Simpson (2006). Fetal arrhythmias. Ultrasound Obstet Gynecol. 27:599-606.

Srinivasan, Strasburger (2008). Overview of fetal arrhythmias. Current Opinions in Pediatrics. 20(5):522-531.

Strasburger, Cheulkar, Wichman (2007). Perinatal Arrhythmias: Diagnosis and Management. Clinical Perinatology. 34(4):627.

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