University of Twente Student Theses


In vitro 3-dimensional modelling of the flow in hypertrophic obstructive cardiomyopathic heart

Graus, E.H.M. and Fennema, A. and Baarsma, M. and Poel, C.B. van der (2021) In vitro 3-dimensional modelling of the flow in hypertrophic obstructive cardiomyopathic heart.

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Abstract:Background: A Morrow procedure is performed in order to relieve the symptoms of hypertrophic obstructive cardiomyopathy (HOCM) patients. The desired thickness of the interventricular septum (IVS) is 10-11 mm, however, this is not patient-specific. Also, intraoperative determination of the IVS-thickness (IVSt) is challenging. Both factors can contribute to the over- and undertreatment of HOCM patients. Aim: To create a set-up to determine the ideal patient-specific IVSt based on the optimal left ventricular outflow tract pressure gradient (LVOT PG) using an in vitro left ventricle (LV) model from a HOCM patient. Materials and Methods: In this research segmented magnetic resonance images of the LV and aorta of a HOCM patient with an IVSt of 19 mm were used to create a mould in 3-Matic. Three virtual Morrow procedures were performed on this mould creating models with IVSt’s of respectively 9, 12, and 15 mm. Afterwards, the moulds were 3-dimensional (3D) printed using a 1 mm thick Polylactic Acid layer and Ultimaker S5 3D printer. Silicone, Dragon Skin 10 NV, was used for casting the models. Next, the moulds were removed and the models were connected to a centrifugal cardiopulmonary bypass pump. A 65/35 volumetric water-glycerol mixture was used to mimic blood. A pulsatile flow was set to 4.0, 5.5, and 6.2 L/min. The LVOT PG was measured for each model using continuous-wave ultrasound. Measurements were conducted at the Medisch Spectrum Twente, Enschede, the Netherlands. Results: The average LVOT PGs in the models for the different thicknesses of the IVS of 9, 12, 15, and 19 mm were respectively 16.7±0.87, 17.2±0.90, 18.0±0.97, and 17.4±0.76 mmHg using a flow of 4.0 L/min, 26.7±0.98, 30.7±1.74, 26.9±1.68, and 31.5±2.29 mmHg using flow of a 5.5 L/min and 34.7±1.78, 32.8±1.31, 33.3±2.43, and 37.3±3.43 mmHg using a flow of 6.2 L/min. Conclusion: This research is the first step in creating a patient-specific model to determine how much tissue needs to be resected when performing the Morrow procedure based on the optimal flow. Even though early results are not yet evidential, it does show that an in vitro model can simulate the blood flow in HOCM patients. In future research adjustments to the model should be made with respect to the inclusion of the mitral valve, pulse settings and heart contractions.
Item Type:Essay (Bachelor)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine BSc (50033)
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