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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 27, No 2, March/April 2016
AFRICA
95
Diagnosing cardiac disease during pregnancy:
imaging modalities
Ntobeko AB Ntusi, Petronella Samuels, Sulaiman Moosa, Ana O Mocumbi
Abstract
Pregnant women with known or suspected cardiovascular
disease (CVD) often require cardiovascular imaging during
pregnancy. The accepted maximum limit of ionising radiation
exposure to the foetus during pregnancy is a cumulative dose
of 5 rad. Concerns related to imaging modalities that involve
ionising radiation include teratogenesis, mutagenesis and
childhood malignancy. Importantly, no single imaging study
approaches this cautionary dose of 5 rad (50 mSv or 50 mGy).
Diagnostic imaging procedures that may be used in pregnancy
include chest radiography, fluoroscopy, echocardiography,
invasive angiography, cardiovascular computed tomography,
computed tomographic pulmonary angiography, cardiovascu-
lar magnetic resonance (CMR) and nuclear techniques.
Echocardiography and CMR appear to be completely safe
in pregnancy and are not associated with any adverse foetal
effects, provided there are no general contra-indications to MR
imaging. Concerns related to safety of imaging tests must be
balanced against the importance of accurate diagnosis and
thorough assessment of the pathological condition. Decisions
about imaging in pregnancy are premised on understanding
the physiology of pregnancy, understanding basic concepts of
ionising radiation, the clinical manifestations of existent CVD in
pregnancy and features of new CVD. The cardiologist/physician
must understand the indications for and limitations of, and the
potential harmful effects of each test during pregnancy. Current
evidence suggests that a single cardiovascular radiological study
during pregnancy is safe and should be undertaken at all times
when clinically justified. In this article, the different imaging
modalities are reviewed in terms of how they work, how safe
they are and what their clinical utility in pregnancy is. Further-
more, the safety of contrast agents in pregnancy is also reviewed.
Keywords:
medical imaging, pregnancy, cardiovascular disease,
X-ray, echocardiography, computed tomography, cardiovascular
magnetic resonance, nuclear cardiology
Submitted 3/9/15, accepted 4/3/16
Cardiovasc J Afr
2016;
27
: 95–103
www.cvja.co.zaDOI: 10.5830/CVJA-2016-022
Pregnant women with known cardiovascular disease (CVD)
or a newly diagnosed cardiac condition in pregnancy often
require cardiovascular imaging during the pregnancy to confirm
the diagnosis, to assess disease severity and stratify risk, to
prognosticate, to plan for appropriate management and to assess
response to therapy (Table 1). A variety of cardiovascular imaging
modalities are available for such purposes and include X-ray
[which encompasses chest radiography, cardiovascular computed
tomography (CCT), computed tomographic pulmonary angio-
graphy (CTPA), coronary computed tomographic angio-
graphy (CCTA), fluoroscopy and invasive angiography],
echocardiography, cardiovascular magnetic resonance (CMR)
and nuclear techniques.
Of these, diagnostic X-ray and nuclear procedures emerge as
the greatest source of concern for patients and clinicians alike.
However, most diagnostic radiological procedures do not expose
the pregnant woman to a degree of radiation that would threaten
the well-being of the developing pre-embryo, embryo or foetus.
1
Furthermore, as cardiological imaging focuses mainly on the chest,
there is minimal direct exposure of the lower abdomen, where the
baby may lie within the main X-ray beam; hence radiation doses
to the developing foetus tend to be small.
2
The mechanisms
of action, safety and clinical utility of various cardiovascular
imaging modalities in pregnancy are considered below.
We performed a systematic search of the published literature
on cardiovascular imaging in pregnancy, published in the English
language, through PUBMED (January 1966 to December 2015),
OVID, Cochrane Database of Systematic Reviews and hand
search of reference lists from selected articles. All search engines
were searched using the key words: ‘pregnancy’, ‘cardiovascular
imaging’, ‘echocardiography’, ‘X-ray’, ‘angiography’,
‘fluoroscopy’, ‘computerised tomography’, ‘cardiovascular
magnetic resonance’ and ‘nuclear cardiology’. Articles with
important insights about cardiovascular imaging in pregnancy
are included.
Ionising radiation and pregnancy
Ionising radiation refers to electromagnetic radiation produced
by X-ray equipment, the radioactive isotopes (radionuclides)
used for radiation therapy (Table 2). The accepted cumulative
dose of ionising radiation during pregnancy is 5 rad (which is
also equal to 50 mSv or 50 mGy),
3
and no single diagnostic study
exceeds this maximum. For example, the amount of exposure
to the foetus from a two-view chest X-ray of the mother is only
0.00007 rad.
4
Division of Cardiology, Department of Medicine, University
of Cape Town and Groote Schuur Hospital, Cape Town,
South Africa
Ntobeko AB Ntusi, FCP (SA), DPhil,
ntobeko.ntusi@gmail.comCape University Body Imaging Centre, Faculty of Health
Sciences, University of Cape Town, Cape Town, South Africa
Petronella Samuels, BTech Rad
Military Hospital, Wynberg, Cape Town, South Africa
Sulaiman Moosa, FFRad Diag (SA)
Instituto Nacional de Saúde and Department of Medicine,
University Eduardo Mondlane, Maputo, Mozambique
Ana O Mocumbi, MD, PhD, FESC