Dr Laurencie Brunel: Understanding the impact of mitral valve replacement

Dr Laurencie Brunel is an accomplished veterinary surgeon with a focus on complex systems. 

After completing her veterinary training in France and Belgium, she moved to Sydney to begin a PhD investigating an established cardiovascular surgery used to treat heart failure in both humans and animals; mitral valve replacement


The mitral valve separates the heart's left atrium and left ventricle, opening to allow blood to flow from the atrium to the ventricle and closing to prevent backward flow. When the mitral valve is damaged or deteriorates, the closure is incomplete, and blood leaks back into the left atrium. This forces the heart to progressively work harder and harder to move the same amount of blood around the body and eventually can lead to heart failure. 

However, Laurencie and her team were interested in determining whether mitral valve interventions were also negatively impacting left ventricular function. “During mitral valve replacement, usually the native anterior leaflet is resected or is modified,” Laurencie says, “mainly to avoid problems of left ventricular outflow tract obstruction. With the transcatheter mitral valve, if it's not resected, it is split or fixed to the prosthesis. So, we really wanted to know if all this intervention on the anterior leaflet would affect the left ventricular function.” 

To test this hypothesis, Laurencie and her team developed a large animal model using merino sheep. “We developed a heart beating, normodynamic ovine model,” Laurencie says, “using a heart beating model is quite interesting because that means we can run several episodes of bypass without having to wait several hours as the heart recovers from the cardioplegia. We are also able to run real-time measurements, pre, and post-mitral intervention, several times.” 

This beating heart model allowed Laurencie and her team to continuously measure arterial pressure, central venous pressure, and cardiac output. They quantified the load-independent contractility of the left ventricle by plotting continuous PV loops through LabChart, giving them a clear view of the impact each intervention had on left ventricular function. 

Related: Introduction to PV loops: Understanding points on the PV loop and measures of cardiac function

“I think we are showing that altering even the most minimal intervention on the native anterior mitral leaflet impairs left ventricular function.” Laurencie says, “And obviously, without the equipment, we would not have been able to show that.” 

“For us, it's gold standard, and so having like the Millar catheters and all the hardware and software from ADInstruments is ideal for us,” she says, “I’m very thankful of the, of the help and the support I got because at the beginning it was quite a steep learning curve. But I mean, each time I needed some help, whether it was for the data acquisition or for the data analysis, the support, like the staff support was like really approachable and helpful and easy to reach.”

Read more about Laurencie's research here:

Brunel, Laurencie, et al. “Splitting the Anterior Mitral Leaflet Impairs Left Ventricular Function in an Ovine Model.” European Journal of Cardio-thoracic Surgery, vol. 63, no. 1, Nov. 2022, https://doi.org/10.1093/ejcts/ezac539.

Laurencie Brunel

Dr Laurencie Brunel, 

Dr Brunel is a senior lecturer at the University of Sydney, and a veterinary surgeon at Veterinary Specialists of Sydney. During her residency, she obtained a Master's degree investigating the urodynamic findings secondary to compressive spinal cord lesions and surgical decompression in dogs. Her PhD investigates the impact of mitral valve replacement on left ventricular function.


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