Review
Heart Disease and Pregnancy: The Need for a Twenty-First Century Approach to Care…

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Pregnancy and childbirth present a specific challenge to the maternal cardiovascular system. Pre-existing cardiac diseases, or cardiac diseases that occur during pregnancy, are associated with a significant risk of morbidity and mortality for both mother and baby. In recent decades, cardiac disease has emerged as a leading cause of maternal death in most high income countries, including Australia and New Zealand.

The burden of cardiac disease in pregnancy is likely to be growing due to an increase in adult survivors with congenital heart disease embarking on pregnancy coupled with demographic shifts in the age and cardiovascular risk factors of women giving birth and the persisting high incidence of acute rheumatic fever in First Nations women. There is widespread consensus that the best obstetric and neonatal outcomes in women with cardiac disease are delivered by a strategy of carefully coordinated multidisciplinary care. Australia and New Zealand currently lack nationally agreed strategies for clinical practice and service delivery for women with heart disease in pregnancy.

This state-of-the-art review summarises some of the key issues faced in relation to prevention, diagnosis, treatment and health service delivery in this patient group and concludes with suggested priorities for policy and research.

Introduction

Pregnancy and childbirth in Australia and New Zealand are as safe as in other high income countries of the world. Maternal deaths in Australasia are reported and reviewed in detail, thus providing a valuable clinical and epidemiological insight into the greatest risks to mothers’ lives during and immediately following pregnancy. Between 2006 and 2016, the maternal mortality ratio (the number of deaths per 100,000 women giving birth) remained below 10 in Australia and fell below 15 in New Zealand in the same period. However, notable inequities persist with rates substantially higher among First Nations peoples [1,2].

Deaths due to maternal cardiac disease are categorised as indirect maternal deaths, that is, deaths caused by previous existing disease or disease developed during pregnancy and not due to direct obstetric causes. In this context, maternal cardiac disease has emerged as the leading cause of maternal mortality in most high income countries. This is a result of demographic shifts in the age and cardiovascular factors of women giving birth in parallel with both an increase in adult survivors with congenital heart disease embarking on pregnancy and substantial reductions in other causes of maternal mortality.

Pregnancy and childbirth present a specific challenge to the maternal cardiovascular system [3]. Cardiac output increases by 30–50% during pregnancy, and is achieved by increased heart rate and stroke volume. These adaptations are apparent from early in the first trimester, before reaching a peak and plateauing in the second trimester. Blood volume also increases by an average of ∼50% (with substantial variability between individuals), due to a combination of increased plasma volume and a proportionately smaller increase in red cell mass. In health, the heart is able to accommodate this increase in preload without a significant increase in filling pressures, and a fall in peripheral resistance (afterload) results in only a minimal increase in systemic blood pressure in the face of increased cardiac output. However, pre-existing or incident cardiac conditions can interact with these physiological changes of pregnancy and increase the risk of maternal cardiac, obstetric, fetal and neonatal adverse outcomes. Additionally, a small body of evidence demonstrates worse outcomes following pregnancy in a number of pre-existing cardiac conditions such as congenital aortic stenosis and in women following surgery that results in a systemic right ventricle [4,5]. Additionally, pregnancy can impact on long-term cardiovascular health. A number of pregnancy specific conditions, for example, gestational diabetes mellitus, gestational hypertension and preeclampsia are known to be associated with an increased future risk of ischaemic heart disease and hypertension (HT) but are not the focus of this article.

The interaction of cardiac disease and pregnancy presents unique challenges across the spectrum of prevention, diagnosis, treatment and health service delivery for both mother and baby. At a systemic level, the opportunity cost and timing of addressing these challenges remains complex due to the broad spectrum of cardiac diseases encountered in pregnancy. In this narrative review, we highlight a number of critical priorities to be addressed in order that the best possible outcomes are achieved, and improved upon, for women with cardiac disease and their children.

Section snippets

Epidemiology

Data concerning the prevalence of cardiac disease coexisting with pregnancy are sparse. The true prevalence of cardiac disease in pregnancy in Australia and New Zealand is unknown. Internationally, consensus documents and reviews have repeatedly cited an estimated prevalence of 1–4% of all pregnancies but these estimates are not based on systematic population based studies or on contemporaneous data [6]. Whilst these numbers appear modest, it is important to remember that pregnancy is common

Mortality and Morbidity Attributable to Maternal Heart Disease

Considerably more information is known regarding the incidence and causes of maternal mortality because of systematic and continuous reporting of maternal deaths in most high income countries of the world. Reports concerning maternal mortality have been published in Australia since 1964 and in New Zealand intermittently since 1998 and routinely since 2005. In both countries, maternal mortality is rare with low rates, therefore caution should be exercised in interpretation. Notwithstanding,

A Growing and Diverse Spectrum of Disease

The aetiology of maternal heart disease has undergone substantial transition in recent decades. Etheridge and Pepperell described the single centre experience of 764 births in 542 women with heart disease between 1950 and 1975 at The Royal Women’s Hospital, Melbourne, Victoria, Australia, and found that over 80% was attributable to rheumatic heart disease [14]. Similarly, the first confidential enquiry into maternal deaths in England and Wales concerning the years 1952–54 reported that 84% of

Patient Reported Outcomes

The majority of our understanding of the impact of maternal cardiac disease on women is derived from clinical registries in which outcome measures have historically focussed on clinical cardiac and obstetric outcomes. With the adoption of woman-centred models of care in maternity services, there is a growing awareness of the additional importance of patient reported outcomes in health care.

A recent meta-synthesis of qualitative research describing women’s experience of heart disease in

Health Systems and Strategy

It is widely accepted that the best obstetric and neonatal outcomes in women with cardiac disease are delivered by a strategy of carefully coordinated, multidisciplinary care which spans the continuum of preconception counselling, through pregnancy and into the postpartum phase [6,7]. Australia and New Zealand lack a coordinated strategic approach to the problem of maternal cardiac disease. Neither the Royal Australian and New Zealand College of Obstetricians and Gynaecologists nor the Cardiac

Conclusions and Priorities

The burden of maternal heart disease is not currently quantifiable in Australia and New Zealand. It is estimated that up to several thousand women and children are affected by the consequences of maternal heart disease every year. The true scale of this impact is poorly understood due to the paucity of research which has been undertaken in this important area. The emergence of cardiac disease as a leading cause of maternal mortality and morbidity in recent decades emphasises its importance and

Conflicts of Interest

None declared.

Acknowledgements

SCK is supported by an Australian Government Research Training Program Scholarship, and by a Postgraduate Scholarship from the Australian National Health and Medical Research Council. WAP, DZ, KL and EAS declare no source of funding for the preparation of this manuscript.

The authors declare no conflicts of interest in relation to this manuscript.

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