Electrical cardioversion in healthy pregnant women: safe yes, but needed?
H. J. G. M. Crijns
H. J. G. M. Crijns (
) Department of Cardiology, Maastricht University Medical Centre
Sustained maternal arrhythmias during pregnancy that
would require an electrical intervention are rare. The
incidence and mechanisms, as well as the need for
intervention, depend strongly on the background disease
of the mother (to be). Electrical intervention may be
indicated only with severe symptoms and drug refractory
arrhythmias. The two cases of attempted electrical
cardioversions (and a concise review of the literature of previous
cases) by Tromp et al. reported in this issue of the journal
 illustrate not only that cardioversion can be done safely
but also that this intervention is hardly ever needed in the
healthy pregnant patient.
In general, maternal arrhythmias are more frequent
than expected and may be due to pregnancy-related
haemodynamic and autonomic changes. The increase in
intravascular volume may lead to stretch of the
myocardium and activity of stretch-activated ion channels and
hence ventricular and supraventricular arrhythmias.
Likewise, increased adrenergic activity may provoke
abnormal automaticity and even re-entry or triggered
activity especially in susceptible patients, i.e. those with
underlying heart disease. Diagnosis and management of
these arrhythmias should take these potential
mechanisms into account, especially since in many cases, an
electrical intervention will not suffice or may even be
futile because of non-shockability of the underlying
arrhythmogenic mechanisms. Instead, arrhythmia treatment
should in the first place consist of rate control.
In the absence of structural heart disease, sustained
arrhythmias are usually atrioventricular nodal re-entrant or
atrial tachycardias, more seldomly atrioventricular
reciprocating tachycardia, and almost never ventricular
tachycard i a . T h e s e a r r h y t h m i a s v i r t u a l l y n e v e r l e a d t o
haemodynamic compromise nor do they need an electrical
intervention. Sometimes healthy pregnant patients develop
troublesome atrial fibrillation, which is most likely focal
and adrenergic in nature. Acute electrical termination is
only needed in the very rare instance when atrial fibrillation
is associated with pre-excitation and ultrarapid ventricular
rate. However, focal lone adrenergic atrial fibrillation is
usually self-terminating, i.e. paroxysmal in nature: if left
alone with sufficient rate control, it will stop spontaneously.
Even though the physical effects are negligible for the foetus,
electrical cardioversion should be avoided, as in the first case
of the report. This holds especially since the trigger for the
paroxysm of atrial arrhythmiaalthough in the end
selflimitingmay still be active and cause acute recurrence,
notably since the trigger is generally non-shockable. In other
words, the patient could have been very well managed
without electrical cardioversion. The above is quite well
illustrated by the second case in which electrical cardioversion
even failed to terminate atrial tachycardia, which had led
to tachycardiomyopathy. Adrenergic activation was
essential for both tachycardia initiation as well as the
development of cardiomyopathy. In such a setting, acute
cardioversion may be futile. Rhythm control can only be
successful after reaching control of adrenergic activation
by heart failure medication including -blockade.
If electrical cardioversion is needed, precautionary measures
as suggested in the report by Tromp et al. should be taken.
However, although seemingly attractive and also advocated by
guidelines , electrical cardioversion is almost never needed
to control arrhythmias in healthy pregnant women.
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