Thomas Kummer


Last Name

Kummer

First Name

Thomas

ORCID

0000-0003-2171-1605

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2022 - 20253
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Publications 1 - 3 of 3
  • Embedded Computational Heart Model for External Ventricular Assist Device Investigations
    Item type: Journal Article
    Kummer, Thomas; Rossi, Simone; Vandenberghe, Stijn; et al. (2022)
    Cardiovascular Engineering and Technology
    Purpose External cardiac assist devices are based on a promising and simple concept for treating heart failure, but they are surprisingly difficult to design. Thus, a structured approach combining experiments with computer-based optimization is essential. The latter provides the motivation for the work presented in this paper. Methods We present a computational modeling framework for realistic representation of the heart's tissue structure, electrophysiology and actuation. The passive heart tissue is described by a nonlinear anisotropic material law, considering fiber and sheetlet directions. For muscle contraction, an orthotropic active-strain model is employed, initiated by a periodically propagating electrical potential. The model allows for boundary conditions at the epicardium accounting for external assist devices, and it is coupled to a circulation network providing appropriate pressure boundary conditions inside the ventricles. Results Simulated results from an unsupported healthy and a pathological heart model are presented and reproduce accurate deformations compared to phenomenological measurements. Moreover, cardiac output and ventricular pressure signals are in good agreement too. By investigating the impact of applying an exemplary external actuation to the pathological heart model, it shows that cardiac patches can restore a healthy blood flow. Conclusion We demonstrate that the devised computational modeling framework is capable of predicting characteristic trends (e.g. apex shortening, wall thickening and apex twisting) of a healthy heart, and that it can be used to study pathological hearts and external activation thereof.
  • Demonstration of a Mechanical External Biventricular Assist Device for Resuscitative Thoracotomy
    Item type: Journal Article
    Sarosi, Kristof; Kummer, Thomas; Roesgen, Thomas; et al. (2025)
    Cardiovascular Engineering and Technology
    Purpose: Resuscitative thoracotomy, a high-risk procedure involving open heart massage, serves as a last resort for life-threatening conditions like penetrating chest wounds, severe blunt trauma, or surgery-related cardiac arrest. However, its success rate remains low, even when primarily carried out by highly trained specialists. This research investigates the potential of an external biventricular assist device (BiVAD). By replacing open heart massage with our BiVAD device during resuscitative thoracotomy, we aim to achieve sufficient cardiac output, maintain physiological pressure levels, and potentially improve patient survival in these critical situations. Methods: The proposed BiVAD system features a 3D printed patch design for direct cardiac attachment, an actuation device, and a vacuum pump. The straightforward design allows quick application in emergency situations. The BiVAD system was tested in an in vitro hydraulic mock circulation, utilizing a silicone heart. Three actuation modes were tested for proof-of-concept: manual patch actuation, standard cardiac hand massage, and utilizing full capabilities of our BiVAD patch system with actuation device operation. Overall performance was assessed on ventricular pressure and flow rate data. Results: Focusing on achieving the optimal cardiac output of 1.5 L/min (critical for patient survival), we tested our patch system against cardiac hand massage at a fixed rate of 60 bpm. The results include raw and statistically evaluated flow rate and pressure measurements for both the left and the right ventricle. Notably, our BiVAD system not only achieved to operate in the range of required cardiac output but also significantly reduced peak pressure in both ventricles compared to standard cardiac hand massage. Conclusion: This initial evaluation using a silicone heart model demonstrates the potential of our BiVAD system to achieve sufficient cardiac output while reducing peak pressure compared to cardiac hand massage. Further development holds promise for effective cardiac support in resuscitative thoracotomy.
Publications 1 - 3 of 3