Introduction

After graduating from the Faculty of Medicine, Dentistry and Health Sciences at the University of Melbourne in Australia, I trained as an anesthesiologist with subspecialty training in obstetric anesthesiology and critical care. Throughout my training, I found the conflicting literature regarding haemodynamics in women with preeclampsia puzzling. The uncertainty in the literature meant that managing critically ill pregnant women with hypertension at the time of emergency birth and during caesarean section could be challenging. The concept that a woman could be relatively hypovolaemic, and critically hypertensive with a low cardiac output did not fit with the clinical picture I observed when regularly managing these critically ill women. I also found the absence of perioperative research and leadership input from anaesthesiologists in the area of preeclampsia intriguing as we facilitate perioperative stabilization, are essential to ensuring safe birth for women with severe preeclampsia and have a unique perspective on haemodynamics in pregnant women with hypertension.

At the same time in Melbourne transthoracic echocardiography, as a bedside tool for haemodynamic assessment was emerging.  This led me to think that transthroaicic echocardiography, being non-invasive, safe and able to give information about ejection fraction, diastolic function, volume status and left and right ventricular function, might be the perfect device for assessing haemodynamic function in women with untreated preeclampsia. In 2007 I began a PhD in the area of haemodynamics in women with preeclampsia using transthoracic echocardiography. By 2010 I had completed my PhD which examined haemodynamics in women with untreated preeclampsia (prior to any treatment interventions) using transthoracic echocardiography and also in gestationally matched healthy pregnant women in order to determine the primary haemodynamic state.¹ This work demonstrated that cardiac output was increased in women with untreated preeclampsia. This challenged the accepted view that women with preeclampsia have low cardiac output with significant vasoconstriction. These data were the catalyst for my further work trying to explain these findings and for the expansion of the role of echocardiography in the clinical management of critically ill pregnant women.

Unified Theory of Preeclampsia

Whilst working as an obstetric anaesthesiologist at the Royal Women’s Hospital in Parkville, Australia, I undertook further studies in Australia, repeated the Australian work in South Africa, attempted to demystify heart failure in women with preeclampsia, and developed a new unified theory of preeclampsia. These studies confirmed the findings of my PhD. The Australian work presented original haemodynamic data using transthoracic echocardiography in women with treated severe preeclampsia. It demonstrated that women with severe treated preeclampsia have preserved ejection fraction, a non-dilated left ventricle and significant diastolic abnormalities, which helps to explain why these women are predisposed to the development of pulmonary oedema. The South African work, performed in collaboration with my friend and colleague Professor Robert Dyer, presented original data in women in South Africa with severe preeclampsia. The haemodynamic findings were similar to Australia – preserved ejection fraction, increased cardiac output and diastolic impairment. This suggested to us that the haemodynamics of preeclampsia are similar regardless of socioeconomic status and geographic location. This enabled the development of the new unified theory of preeclampsia.²

In the immediate years after my PhD it became apparent that there was a large misunderstanding and mystification regarding the concept of cardiac failure in women with preeclampsia, such that women with heart failure in this setting frequently were labeled as having peripartum cardiomyopathy. As hypertension is a known precipitant of cardiac failure and there are clear mechanisms of heart failure in women with critical hypertension, the diagnosis of peripartum cardiomyopathy is erroneous. In order to demystify heart failure in women with preeclampsia, with colleagues I wrote two articles – one explaining why pregnant women with hypertension develop pulmonary oedema,³ and one comparing echocardiographic findings in preeclampsia with those of peripartum cardiomyopathy.⁴

Challenging The Status Quo

In 2014 with my friend and colleague Dr Julian Castro, based on the haemodynamic work over the previous six years and bringing in concepts of hypertension from the non-pregnant literature, we developed and presented a new unified theory of preeclampsia.² It proposed that preeclampsia is an adaptive (not maladaptive) maternal response to the presence of the fetus driven by an imbalance between maternal oxygen supply to the fetus and fetal oxygen demand. This challenges the status quo and presents for the first time an alternative theory that explains all the features of preeclampsia. As new onset hypertension in pregnant women is multifactorial and an adaptive response to the developing fetus there will never be a unique biomarker for the condition or a single drug therapy to treat all women. Rather what is needed is a collaborative individualised approach to women with hypertension in pregnancy, serious efforts at addressing the prevention of preeclampsia,  and the mainstreaming of hypertension occurring in pregnant women rather than isolating it from the rest of the medical community due to its historical, mystical “pregnant womens business” label of preeclampsia.

In 2016 I began a Master of International Public Health at the University of Sydney Australia as I realised that gender inequity was a major reason why maternal mortality and morbidity from hypertension in pregnant women still occurs.⁵ Prevention of new onset hypertension in pregnancy is possible if the 222 million women throughout the world who want access to contraception but don’t have it are granted it.⁶ Reducing the number of women suffering and dying from hypertension in pregnancy is possible by implementing what we already know. This includes providing quality antenatal care, treating hypertension and preventing seizures, providing critical care management and having access to safe anaesthesia and surgery so that timely birth with the right people in the right place can occur.

My on-going work includes clinical, research and teaching at the Royal Womens Hospital. I am grateful to my wonderful family, friends and colleagues and most importantly to the pregnant women, healthy and unwell who inspire me each day.

References

1. Dennis AT, Castro J, Carr C, Simmons S, Permezel M, Royse C. Haemodynamics in women with untreated pre-eclampsia. Anaesthesia 2012;67:1105-18.
2. Dennis AT, Castro JM. Hypertension and haemodynamics in pregnant women – is a unified theory of pre-eclampsia possible? Anaesthesia 2014;69 1183-9.
3. Dennis AT, Solnordal CB. Acute pulmonary oedema in pregnant women. Anaesthesia 2012;67:646-59.
4. Dennis AT, Castro JM. Echocardiographic differences between preeclampsia and peripartum cardiomyopathy. International Journal of Obstetric Anesthesia 2014;23:260-6.
5. The Global Gender Gap Report 2016. World Economic Forum. ISBN 9978-1-944835-05-7 Viewed 9th April 2017. http://www3.weforum.org/docs/GGGR16/WEF_Global_Gender_Gap_Report_2016.pdf
6. World Health Organization 2014. Ensuring human rights in the provision of contraceptive information and services:guidance and recommendations ISBN 978 92 4 150674 8. Viewed 9^th April 2017. http://www.who.int/reproductivehealth/publications/family_planning/human-rights-contraception/en/