Download Factors Influencing the Presence of Mitral Valve Prolapse in

REVIEW
Factors Influencing the Presence of Mitral
Valve Prolapse in Pregnant Women with
Congenital Heart Sisease
Soedaba Sina Ashraf, Erasmus University College
Abstract
Mitral valve prolapse is a cardiac condition in which the mitral valve is incompetent. With the use of
sex-specific risk factors and risk markers, it is possible to detect the severity of a mitral valve prolapse
in pregnant women with congenital heart disease. Withal, in many cases these women are not aware
of having cardiac problems and therefore it is crucial to create awareness amongst them and also
amongst physicians. During pregnancy, there is an increase in cardiac output that could possibly
worsens pre-existing cardiac conditions. Most of these patients can tolerate their pregnancy well if
they receive an adequate medical control. However, pregnancy should be avoided when there is a
high chance of developing mitral valve prolapse. Finally, the necessity of future research to identify
underlying mechanisms influencing the risk factors and risk markers of cardiovascular disease in
women will be discussed.
Introduction
Cardiovascular diseases are leading causes of deaths
in The Netherlands [1]. In a recent study, the incidence of cardiac diseases in pregnant women was
estimated to be 0.5%. Among them, mitral valve
disease resulted to be the most common type with
39.2% and mitral regurgitation (MR) with 19.9%
[2]. Mitral valve prolapse (MVP) also known as
Barlow’s syndrome or “click-murmur syndrome”, is
mainly associated with the presence of floppy mitral
valve(s) [3]. When the mitral valve is incompetent,
blood can flow back out of the left ventricle into the
left atrium during systole [4]. Therefore, the aim
of this review is to identify the factors that increase
the risk of developing a mitral valve prolapse in
pregnant women with congenital heart disease.
The first section focuses on both cardiovascular
disease (CVD) in women in general and the risk factors directly or indirectly causing the disease. This is
followed by the mechanisms of MVP, and the descriptions of hemodynamic and cardiovascular changes
that occur during pregnancy in healthy women. The
maternal and foetal outcomes of patients with MVP
with congenital heart disease will also be discussed.
Finally, the diagnosis and treatment of patients in
this risk group will be analysed.
Cardiovascular Disease in Women
Heart disease results in more deaths among women
than other common diseases such as stroke, lung
cancer, chronic obstructive lung disease, and breast
cancer [5].
The first factor influencing mortality among
women is lack of awareness. A survey in 1997
showed that only 30% of American women, who
participated in the study, knew that CVD has been
the leading cause of death among women. Over the
years, this amount has been improved up to 54% [6].
The main reason of this obliviousness, has been the
lack of guidance or preventive treatment for women
compared to men at similar ASCVD risk. Moreover, previous epidemiologic studies have shown a
relation between risk markers and CVD [7]. For
example, a research performed by the EUGenMed
group showed that the biological sex distinctness
between men and women are not only caused by a dissimilar gene expression from the sex chromosomes,
but also by sexual hormones that play a fundamental
role due to their influence in gene expression and
the function of the cardiovascular system [8].
Other identified causal risk factors and associative risk markers are the type 2 Diabetes Mellitus,
smoking, obesity, lack of physical activity, dyslipi-
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daemia and hypertension. It has been shown that the
consequences of these risk factors lead to a poorer
prognosis in women than men [6].
Mitral Valve Prolapse
The mitral valve is one of the four valves from the
human heart located in the left part of the heart. It
can be found between the left atrium and the left
ventricle. The valve opens as soon as the pressure
in the left atrium is increases, as it gets filled with
blood. While the valve is open, blood can flow into
the left ventricle as the ventricular muscles are in
a relaxed state (diastole). Once the left ventricle is
filled with enough blood the mitral valve closes in
order to prevent the blood flowing back into the left
atrium. In this state, the heart contracts (systole) and
blood is being forced into the aorta [9]. However,
when the mitral valve does not function properly,
it can lead to physiological consequences that can
generate congestive heart failure, arrhythmia, and/or
sudden death [10].
The mechanical changes of the mitral valve can
be caused by a myxomatous degeneration. This
change in progressive tissue, aggravates the prolapse
and eventually provokes chordal rupture. Nevertheless, the histological degeneration is not always
followed by regurgitation as it is dependent on the
stress-strain relation. Regurgitation occurs when
both leaflet injury, chordal injury, and elongation
are involved at the same time [10].
Hemodynamic and Cardiovascular Blood Flow
in Pregnant Women
In order to fully understand how MVP works in
pregnant women with congenital heart disease, it
is essential to first look at the hemodynamic and
cardiovascular blood flow in pregnant women.
Hemodynamic and physiological changes in the
cardiovascular system of pregnant women are profound because it is needed to fulfil the increased
metabolic demands of both mother and foetus. The
adaptive changes consist of an increase in cardiac
output due to vasodilation, blood volume expansion
due to sodium and water retention, and reductions in
systemic vascular resistance and systemic BP [11].
Moreover, the increased cardiac output during rest results in having the maximal cardiac output triggered
at a lower level of work during exercise. Compared
to non-pregnant women, the maternal oxygen uptake is also increased during rest or weight-bearing
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exercise such as walking or treadmill exercise [12].
Eventually, these changes will settle down into the
uteroplacental circulation that ensures foetal growth
and development. In contrast, once the metabolic
demands cannot be fulfilled by the hemodynamic
changes, maternal and foetal morbidity can occur
[11].
Mitral Valve Prolapse in Pregnant Women with
Congenital Heart Disease
After having looked into hemodynamic and blood
flow changes in normal pregnancy and how MVP
works, the presence of MVP in pregnant women with
congenital heart disease will be better understood
now.
Many patients with valvular heart disease (VHD)
often did not know they had it before pregnancy. In
these patients, the presence of abnormal pregnancy
symptoms made them aware of the fact that there
was something wrong. From all the causes of cardiac
dysfunction in pregnant women, 63% was caused
by mitral regurgitation. Moreover, the majority of
the maternal mortality rate was higher with VHD
than with coronary heart disease [13].
Previous studies have proven that mitral regurgitation is generally well tolerated in pregnancy [14, 15].
Yet, when there is the case of ventricular dysfunction
or an additional valve lesion, the risk of developing
a prolapse will increase. Mitral regurgitation is no
longer a mild case under the aforementioned conditions. Therefore, preventive measures are vital to
avoid further complications [16].
The decision of whether the specific regurgitant
mitral valve is needed to be repaired or replaced is
complex and is dependent on individual situations.
In severe cases, surgery of the valve is required and
the risk should be assessed once the left ventricle is
dilated or its function has begun to decrease [16].
In the case of the foetus, it has been proven that patients with non-myxomatous MVP presented little or
no risks during pregnancy and had excellent neonatal
outcomes [14]. Thus, as long as the maternal-foetal
interactions are not endangered, pregnancy is permitted [15].
Diagnosis and Treatment
Patients with severe valvular disorders (e.g. myxomatous MVP combined with MR)are advised to
avoid pregnancy due to high risks of morbidity for
both the mother and the foetus. On the other hand,
REVIEW
pregnancy in patients with mild valvular disorders
can be kept under control with regular check-ups by
specialists (including obstetrician, cardiologist, and
obstetric anaesthesiologist). In this way, mild valvular disorders are tolerable during their pregnancy [9].
The diagnosis and assessment of the valvular disorders are mainly carried out using echocardiography
[17]. This is the main clinical tool used in pregnant
women with congenital heart diseases, as it is safe
and non-invasive for both the mother and the foetus.
Subsequently, an electrocardiogram (ECG) is used
to look for signs of ischaemia, especially when in the
case of MR [9]. Additionally, patients who still want
a surgical mitral valve treatment during pregnancy
can undergo a percutaneous mitral valve repair with
a mitral clip. This technique entails clipping of the
two leading ends of the leaflets to one another. This
technique aids in lessening the symptoms, but it
is less effective in the complete reduction of MR
because some patients needed a subsequent surgical
treatment due to infections caused by the clip [9].
Conclusion
In general, it is important for both physicians and
pregnant women with congenital heart disease to
be aware of the risk factors and risk markers of
mitral valve prolapse. This prevents serious complications for both the mother and the foetus during
pregnancy, as most of the time, patients with CHD
are not aware of their own cardiac condition. In this
case, patients with severe conditions are counselled
to avoid pregnancy and also, women with MVP
without other CVD whom often are able to tolerate
pregnancy well can have a better medical control.
Nevertheless, more research to identify the mechanisms influencing sex specific risk factors and risk
markers areis required. This will not only improve
the knowledge on the pathogenesis of MVP, but also
enable physicians to identify the condition better
and consequently, offer a better treatment.
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