MATERNAL
CARDIAC RHYTHM DISORDERS IN NORMAL PREGNANCY Ní
Bhuinneáin M, McKenna P, O'Herlihy C, Sugrue D Rotunda
Hospital & Mater Misericordiae Hospital,
Dublin, Ireland Study Hypothesis: Healthy pregnant women, without apparent
heart disease, who present with symptoms such as palpitations and
presyncope, pose a clinical problem for the obstetrician, as not
all can be offered cardiological referral. The exact incidence of
cardiac arrhythmia in this population is unknown[1]. Theoretically,
the haemodynamic change and the altered autonomic responsiveness
of pregnancy, in addition to psychological stress can predispose
to arrhythmia. This study tests the hypothesis that the pregnant
state facilitates arrhythmogenesis in women, without apparent heart
disease, through inhibition of vagal cardiac modulation. Methods: An observational cohort study of 100
healthy, Caucasian women of mixed parity. Congenital arrhythmias, thyroid
dysfunction and anemia were excluded prior to study entry. Subjects attended a
designated research antenatal clinic and were monitored with domiciliary
24-hour ambulatory electrocardiography at eight-week intervals from 6 weeks
gestation and in the postnatal period. The tapes were analysed with a Reynolds
Medical Pathfinder 600 by a single observer (MNB). Outcome measures were
cardiac arrhythmias and time domain measures of heart rate variability as per
standard criteria. Microsoft Excel was used as the database and SPSS was used
for statistical analysis. Results: 29 women were symptomatic during the
monitoring periods and all 29 had cardiac arrhythmias on ambulatory
electrocardiography. The symptomatic episodes did not correlate with the rhythm
disturbance. 64 of the 71 asymptomatic women also had rhythm disturbance on
electrocardiography. The distribution of rhythm disturbance in both groups
included sinus node, atrial and ventricular arrhythmias. Only one patient
reported symptoms during the post-natal period confirming a statistically
significant reduction in symptoms (p<0.001). 72 women had persistent
electrocardiographic abnormalities during the postnatal period - a significant
reduction from the antenatal period (p<0.001). Heart rate variability
analysis confirmed vagal inhibition in all trimesters of pregnancy compared
with the non-pregnant state. Conclusion: Benign cardiac arrhythmias are common in
pregnant women without apparent heart disease. Symptoms are not predictive of
the frequency or nature of the arrhythmia and rhythm disturbances persist
throughout pregnancy despite a decrease in reported symptoms. The return to a
lower frequency of both symptoms and arrhythmias in the puerperium supports the
hypothesis that pregnancy facilitates arrhythmogenesis. The data alert the clinician to the role of
pregnancy as a "cardiac stress-test" and provide a reference range of normality
for comparison with high-risk pregnancy. 1.
Elkayam U, Gleicher N.
Cardiac Arrhythmias and Pregnancy. In: Cardiac Problems in Pregnancy 3rd ed . Wiley-Liss; 1998;
13:155-174.
