Home Medizin MIT-Forscher entwickeln neuen Test für die Eignung von Herzunterstützungsgeräten

MIT-Forscher entwickeln neuen Test für die Eignung von Herzunterstützungsgeräten

von NFI Redaktion


Each year, approximately 50,000 individuals in the United States experience cardiogenic shock – a life-threatening condition typically caused by a severe heart attack, where the heart is unable to pump enough blood to meet the body’s demand.

Many of these patients eventually receive assistance from a mechanical pump, which can temporarily help the heart pump blood until it has sufficiently recovered to function independently. However, nearly half of these patients experience an imbalance between the left and right heart chambers, which can be dangerous for the patients.

In a new study, MIT researchers have discovered why this imbalance occurs, and identified factors that make it more likely to occur. They have also developed a test that doctors can use to determine if this dysfunction is occurring in a particular patient. This could provide doctors with more confidence in deciding whether to use these pumps, called ventricular assist devices (VADs).

“As we improve our mechanistic understanding of how these technologies interact with native physiology, we can optimize device utility. And as we have more algorithms and metric-based guidance, this will make usage more facile for the physicians. This will improve outcomes in these patients and expand the use of these devices more broadly.”


Kimberly Lamberti, MIT doctoral candidate and lead author of the study

Elazer Edelman, Edward J. Poitras Professor of Medical Engineering and Science at MIT’s Institute for Medical Engineering and Science, is the senior author of the article which today appears in Science Translational Medicine. Steven Keller, Assistant Professor of Medicine at the Johns Hopkins School of Medicine, is also an author on the article.

Edelman notes that „the beauty of this study is that it uses pathophysiological insights and advanced computational analytics to provide clear guidelines for the explosion of utilization of these valuable mechanical devices. As we increasingly use these devices in our ill patients, we now have better strategies to optimize their utility.“

Heart Imbalance

For the treatment of patients experiencing cardiogenic shock, a percutaneous VAD can be introduced through the arteries until it is positioned above the aortic valve, helping pump blood from the left ventricle. The left ventricle is responsible for pumping blood to most organs of the body, while the right ventricle pumps blood to the lungs.

In most cases, the device can be removed after about a week, once the heart is able to pump independently. While the devices are effective for many patients, they can disrupt the coordination and balance between the right and left ventricles in some individuals, which contract and relax synchronously. Studies have found that this disruption occurs in up to 43 percent of patients who receive VADs.

“The left and right ventricles are strongly coupled. When the device interferes with flow through the system, this can unmask or induce right heart failure in many patients,” says Lamberti. “This is a known issue, but the mechanism by which it occurs is unclear, and there are limited metrics to predict in which patients it will occur.”

In this study, the researchers aimed to understand why this failure occurs and find a way to help doctors predict whether this failure will occur in a specific patient. If doctors knew that the right heart also needs support, they could implant another VAD to support the right ventricle.

“Our aim with this study was to predict any issues earlier in the patient’s disease course so that interventions can be made before they reach this extreme failing state,” says Lamberti.

To this end, the researchers examined the devices in an animal model for heart failure. A VAD was implanted into each animal’s left ventricle, and the researchers analyzed various measurements of heart function while the device’s pump speed was increased and decreased.

The researchers found that the most crucial factor for the right ventricle’s response to VAD implantation was how well the pulmonary vascular system functioned – the vessel network that transports blood between the heart and lungs – adapting to changes in blood volume and flow induced by the VAD.

This system was best able to accommodate this additional blood flow when it was able to adjust its resistance (slowing down of the even blood flow through the vessels) and compliance (slowing down of large blood volume pulses into the vessels) due to the changes induced by the VAD.

A Dynamic Test

The researchers also demonstrated that measuring this pulmonary vessel compliance and its adaptability could provide a way to predict how a patient will respond to the support of the left ventricular. The researchers found that these measurements correlated with the condition of the right heart and predicted how well the patients had adapted to the device, thus validating the results of the animal study.

To perform this test, doctors would need to implant the device as usual and then increase the speed while simultaneously measuring the compliance of the pulmonary vessel system. The researchers identified a metric for evaluating this compliance using only the VAD itself and a pulmonary artery catheter typically implanted in these patients.

“We have developed this method to dynamically test the system while maintaining support of the heart,” says Lamberti. “Once the device is in operation, this rapid test could be carried out, informing physicians whether the patient may require right heart support.”

The researchers now hope to expand these findings through further animal studies and continue collaborating with manufacturers of these devices in the future, aiming to conduct clinical trials to assess whether this test would provide valuable information for doctors.

“Currently, there are few metrics used to predict device tolerance. Device selection and decision-making are generally based on physician experience within individual institutions. With this understanding, doctors can hopefully determine for which patients intolerance could occur,” “Supporting us in device support and providing guidance on how best to handle each patient based on the condition of the right heart,” says Lamberti.

The research was funded by the National Heart, Lung and Blood Institute, the National Institute of General Medical Sciences, and Abiomed.

Source:

Massachusetts Institute of Technology

Journal Reference:

Lamberti, KK, et al. (2024) Dynamic Load Modulation predicts the right heart tolerance of left ventricular circulatory support in a porcine model of cardiogenic shock. Science Translational Medicine. doi.org/10.1126/scitranslmed.adk4266.

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