Houston Methodist Researchers Push the Envelope with an Innovative Vacuum Coupler for Open-chest Cardiac Ultrasound Mediated Imaging

A new 3D-printed vacuum coupler significantly reduced cardiac motion during ultrasound (US)-mediated imaging in an open-chest heart model, according to a Houston Methodist study that shows promise for reducing inaccuracies and improving patient outcomes.

The coupler, designed by Dr. Carly S. Filgueira, a Houston Methodist assistant professor of nanomedicine, produced superior data and more stable images compared to other common methods of US-mediated imaging. The coupler works by stabilizing an US transducer on the epicardial surface of the heart.

“Open‐chest cardiac ultrasound imaging using a vacuum coupler allowed for reduced tissue displacement and an increased number of frames that maintained a high correlation throughout multiple cardiac cycles,” said Dr. Filgueira, a study author. “Such a coupling device facilitates the development of cardiac ultrasound‐mediated imaging strategies with prolonged acquisition times by improving interframe stability during open‐chest imaging procedures.”

The study was published in Medical Physics.

Cardiovascular Disease Burden in the U.S.

Cardiac diseases pose massive burdens in the U.S., both physical and economic. It’s the leading cause of death (more than 900,000 annually) and disability, and the yearly costs exceed $400 billion.

Effective diagnosis and monitoring of cardiovascular diseases are the key to significantly reducing the number of deaths. There is huge potential to improve patient outcomes through early detection, risk management and timely acute care.

US-mediated imaging is crucial for the diagnosis and monitoring of various cardiac diseases and conditions, including cardiomyopathy, ischemic heart disease, early graft failure, myocardial infarction, valvular heart disease, heart failure, congenital heart defects, pericardial disease, atherosclerosis, pulmonary hypertension and conditions related to blood clots. This real-time, cost-effective, portable and non-invasive technique has myriad additional applications including verifying pregnancy, imaging abdominal organs, guiding procedures such as biopsies, and advanced therapies such as targeted drug delivery and tumor ablation.

Challenges of Ultrasound Imaging During Open-Chest Procedures

But a fundamental challenge of using US-mediated imaging in the context of cardiovascular diseases and open-chest procedures is cardiac motion, which can generate artifacts and inaccuracies. Surgery introduces several challenges in open-chest cardiac US procedures, including artifacts, metallic interference, blood-obscuring views and tissue edema. Current imaging modalities have significant limitations that can cause complications during surgery.

Dr. Filgueira’s vacuum coupler attempts to circumvent these longstanding challenges.

How the 3D-Printed Vacuum Coupler Stabilizes Cardiac Ultrasound Imaging

In collaboration with Dr. Richard R. Bouchard, a professor in the Department of Imaging Physics at the University of Texas MD Anderson Cancer Center, Dr. Filgueira designed this prototype using a 3D printer and commercially available biocompatible resins. Hence, this vacuum coupler or adaptor can be reproduced in any laboratory. Furthermore, precautions were taken to ensure this device was free from any metal components and any other aspects that would interfere with the US-mediated imaging.

Using a preclinical model, Dr. Filgueira and her team compared conventional handheld imaging, stand‐off imaging, a coupler without suction and the vacuum coupler with suction. They found that the suction capability led to superior data and more stable images.

The vacuum suction integrated into the design allows the US transducer to adhere to the live heart enabling this device to be hands-free.

The vacuum coupler enhances imaging capabilities during open-chest cardiac imaging due to the longer acquisition times and stability that it offers. This is particularly useful since the heart is constantly beating and extra stability is needed.

“The heart is a really challenging organ to image. Our goal was to create a transducer without any metal components or anything that would interfere with the imaging, without causing any damage to the heart,” said Dr. Filgueira.

The vacuum coupler allows consistent sampling of an intended region of interest of the heart over multiple cardiac cycles.

The use of the vacuum coupler significantly improved image stability which translated to more physiologically reliable imaging outputs.

“If the data that you are starting with is not great, the post-processing analysis will not be the best,” added Dr. Filgueira. “Because we were able to make this cool, workable device, we now use it every time we image for our other research projects. We are also happy to print this device and ship it to another researcher who wants to use it, as this would certainly advance the field.”

Potential Clinical and Research Applications of the Vacuum Coupler

The current design is limited to open-chest, epicardial imaging. However, this concept can be extended to less invasive applications in the near future and the development of advanced cardiac, US-mediated imaging approaches, thereby expanding the technical possibilities in both preclinical and select clinical settings.

Dr. Filgueira’s findings demonstrate that mechanical stabilization at the epicardial surface of the heart can significantly improve image quality in motion-sensitive US-mediated imaging approaches. These techniques can also be used for intraoperative assessments of local cardiac perfusion as well as tissue characterization.

Dr. Filgueira noted that although the most imminent use of this platform is for improved preclinical development of advanced ultrasound‐mediated imaging approaches, “there could also be limited application for certain clinical procedures (e.g., coronary bypass graft assessment), which are performed with an open‐chest preparation.”

This research was supported by NIH grant R21 HL159534 to Drs. Bouchard and Nilesh Mathuria; the George and Angelina Kostas Research Center for Cardiovascular Nanomedicine to Drs. Mathuria and Filgueira; the John S. Dunn Foundation Collaborative Research Award to Drs. Bouchard and Filgueira; Houston Methodist Hospital to Dr. Mathuria; and Houston Methodist Research Institute to Dr. Filgueira.

Nilesh Mathuria, Krithik Vishwanath, Giorgio Brero, Blake C Fallon, Antonio Martino, Richard C Willson, Carly S Filgueira, Richard R Bouchard. Open-chest cardiac ultrasound-mediated imaging with a vacuum coupler. Med Phys. 2025 Feb;52(2):880-888. doi: 10.1002/mp.17511.