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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Louis Fixsen (Eindhoven University of Technology)
Niels Petterson (Eindhoven University of Technology)
Frans van de Vosse (Eindhoven University of Technology)
Marcel Ruttern (Eindhoven University of Technology)
Richard Lopata (Eindhoven University of Technology)

Abstract:
In mechanical circulatory support (MCS) patients, clinicians lack tools to monitor the condition of the heart due to metals in the body. Factors such as LV dP/dtmax and contraction pattern are valuable in assessing cardiac function, but have yet to be quantified in MCS patients. Ultrasound (US) strain imaging could enable the study of these parameters. However, due to a high level of illness it is difficult to validate new methods in MCS patients. Therefore, in this study, 2-D US strain imaging was used to investigate changes in heart mechanics in left ventricular assist device (LVAD) supported hearts, with an isolated beating porcine heart platform. Ex vivo porcine hearts were implanted with Thoratec HeartMate II (n=2) and MicroMed DeBakey (n=2) LVADs. The hearts were attached to a mock-loop, re-perfused with oxygenated blood, resuscitated and paced at 120 bpm (PhysioHeart, LifeTec). Measurements were performed whilst the LVAD-supported hearts deteriorated from baseline condition (based on cardiac output). Radio-frequency US data were acquired (MyLab70, Esaote) at pump speeds from 0 (no outflow) to 10.5 krpm. Data were manually segmented and local radial (erad) and circumferential strains (ecir) were estimated over each heart cycle. The unloaded 0 krpm initial geometry was used as an initial condition for further pump speeds per heart condition. In each heart, as the pump speed was increased and the hearts degraded, measured dP/dtmax reduced. An increase was seen in ecir magnitude relative to the reduction in pressure, showing that ecir estimated using US strain imaging can be related to dP/dtmax. Time-to-peak strain around the left ventricle was measured. As the pump speed was increased and the heart condition degraded, regions of early and late contraction grew in size and magnitude. This is a first step in unravelling the interplay between pump-action and remaining cardiac function. This work was funded by the EU-MSCA. GA No 642612 (www.vph-case.eu).