Preeclampsia is a human pregnancy specific hypertensive (high blood pressure) cardiovascular disease that is a leading cause of global morbidity and mortality. In Australia, preeclampsia affects approximately 20,000 pregnant women each year, is the most common reason to be admitted to an intensive care unit during pregnancy and is responsible for 20% of the maternal deaths. Worldwide it affects 6.5 million young women each year and is a leading global cause of maternal mortality. The hypertension and its complications, including renal impairment, acute pulmonary oedema, systolic and diastolic cardiac failure, and intracerebral haemorrhage, are directly related to the cardiovascular system and altered haemodynamics (blood flow).
The proposed unique and innovative study aims to investigate the heart in women with preeclampsia using non-invasive technologies of ultrasound, transthoracic echocardiography (TTE) and cardiovascular magnetic resonance (CMR). Using these safe methods it is anticipated that the study will improve understanding of preeclampsia, lead to better monitoring and the use of different medications to reduce complications in preeclampsia.
Cardiovascular magnetic resonance (CMR) is a relatively new imaging modality for cardiovascular assessment. It is able to provide excellent, high quality images that can be obtained in any plane and without restriction by body size and morphology. It is non-invasive and does not utilise radiation both of which are important considerations in pregnant women. As it is able to visualise the heart so well, cardiovascular magnetic resonance is an important part of the assessment of cardiovascular structure and function. Cardiovascular magnetic resonance is currently the gold standard for left ventricular volumes and function, and is the only imaging modality currently available that is able to formally quantify right ventricular volumes and function.
By observing women with preeclampsia, this study aims to further determine the differences in cardiac structure in women with preeclampsia, before and after birth. By performing observations in the antenatal period and then at six months post-birth, information about initial cardiac changes followed by recovery of cardiac changes will be able to be gathered. This information will then assist with understanding of cardiac changes in women with preeclampsia. This in turn may lead to additional or alternative therapeutic or monitoring interventions such as serial echocardiography to monitor disease progress and resolution, and CMR to assess extent of myocardial oedema or fibrosis and potential for recovery. It may also lead to consideration of the use of diuretics to reduce tissue oedema and improve cardiac function and the use of cardiac remodelling agents, such as angiotensin converting enzyme inhibitors in women after birth who demonstrate cardiac structural changes, all of which may reduce short and long term morbidity from this condition.
Professor Alicia Dennis at The Royal Women’s Hospital, Melbourne
The team included:
Dr Sylvia Chen, Epworth Hospital, Melbourne
Dr Julian Castro, St Vincent’s Hospital, Melbourne
Dr Allan Wesley, The Prince Charles Hospital, Brisbane
The project was awarded $A66,591 through the ANZCA research grants program in 2017.
This was the first study to use cardiac magnetic resonance (CMR) to determine myocardial structure in women with preeclampsia, and the first to demonstrate myocardial oedema as a component of increased left ventricular mass in these women.
Preeclampsia is a devastating high blood pressure problem of pregnancy, with childbirth the only cure. Professor Dennis’ team believed the key to understanding why preeclampsia occurs, and to finding better treatments, was to examine the heart using transthoracic echocardiography (TTE) and CMR, and aimed to improve understanding leading to better monitoring and the use of different medications to reduce complications in preeclampsia.
The specific aim was to define myocardial tissue characteristics using CMR and correlate with TTE in the antenatal period, determining whether observed changes return to non-pregnant reference values by six months post-birth.
This research work was the first-time in which analysis of the heart muscle was shown in patients with preeclampsia. It demonstrated that in a small cohort of patients the myocardial thickness observed on echocardiography was due to myocardial oedema, and not myocardial fibrosis, improving understanding of the pathophysiology of the condition, with implications for future treatments.
The study was an important one in a series of projects being led by Professor Dennis to understand the structure and function of the heart in people with preeclampsia, the underlying pathophysiology mechanism behind the condition, and potential solutions to the problem of high blood pressure in pregnant people. It contributed to Professor Dennis’ 2023 Fulbright Scholarship to undertake further work in this area at the Brigham and Women’s Hospital, and Harvard Medical School in Boston, USA, in 2023.
Chen SSM, Leeton L, Castro JM, Dennis AT. Myocardial tissue characterisation and detection of myocardial oedema by cardiovascular magnetic resonance in women with pre-eclampsia: a pilot study. International journal of obstetric anaesthesia. 2018 Nov; 36:56-65. https://doi.org/10.1016/j.ijoa.2018.07.004