MSCA-COFUND-CLEAR-Doc-PhD Position #CD22-25: Investigation of Ventricular septal defect– the impact of traffic road accidents on specific patient

This PhD project aims at investigating the impact of traffic road accident and understand the mechanism associated with post traumatic ventricular septal defect.

Cardiac injury is a common complication of blunt chest trauma (BCT). Myocardial contusion is the most frequent cardiac injury following BCT and occurs in 16–76% of patients in motor vehicle accidents. Other common injuries include valvular damage, and aortic insufciency. However, traumatic ventricular septal rupture or defect (VSR or VSD) is a rare complication of BCT.

The mechanisms of traumatic VSD occurring from blunt trauma have been of little concern until now, but two dominant theories have been described. The first postulated mechanism of VSD is acute compression of the heart between the sternum and the vertebral column, with a resultant sudden rise in intracardiac pressure at the end of diastole or isovolumetric systole. The second postulated mechanism is microvascular disruption caused by myocardial injury, leading to infarction and liquefaction of the septum.

Integration of patient-specific flow condition as well as cardiac function (left ventricle - LV and right Ventricle-RV interactions) could be beneficial to patient-specific simulation of accident and validation of evocated hypothesis. Such PhD project will then provide: flow based patient-specificity implemented through 1D lumped model (Part 1), LV-RV specific interaction and fillings according to patient (Part 2) and finally a validation bench which could be used for further application (aortic blunt dynamic for example).

Part 1 of the PhD program is the investigation of the mechanism based on a literature review and using a 1D lumped model of the heart based on Circadapt code (Arts et al., 2003, 1991). This first part aim at simulating the different hypothesis in term of pressure volume modification: this is to say simulating the effect of blunt and blood circulation. This part including the literature review will enable to determine the necessary modification of the developed lumped model to take into account the different pathophysiology.

Part 2 of the PhD program aims at quantifying the change in flow associated with ventricle and septal morphological and anatomical change. Indeed, previous simulation and the use of specific 3D+t phased contrast MRI sequence enable the quantification of intra-cardiac flow (Evin et al., 2019). Based on previously developed model of left ventricle, the study will be investigating 1) the modification in ventricular contraction and filling pressure and volumes of both ventricles in case of acute VSD 2) the modification of pulmonary flow and its impact in those conditions.

Part 3 of this PhD program is the creation of a cardiac simulator for the validation of the heart model and using particle image velocimetry. Such phantom creation will enable to reproduce alteration of the ventricular filling and pressure using a two chambers phantom. Water glycerol will be used for mimicking the blood and the quantification of the flow pattern will be done using different approaches of fluid-dynamics. The phantom to be created will be MRI compatible and usable with particle image velocimetry. All system (pumps, pressure and flow sensors, PIV) are available at the laboratory.

This PhD program is performed in collaboration between two laboratories: the CRMBM (CNRS, UMR 7339) specialized in magnetic resonance imaging sequences and the LBA (TS2, Université Gustave Eiffel) and the AP-HM.

References

Amorim MJ, Almeida J, Santos A, Bastos PT. Atrioventricular septal defect following blunt

chest trauma. Eur J Cardiothorac Surg. 1999;16:679–82.

Arts, T., Bovendeerd, P., Delhaas, T., Prinzen, F., 2003. Modeling the relation between

cardiac pump function and myofiber mechanics. J. Biomech. 36, 731–736.

https://doi.org/10.1016/s0021-9290(02)00451-7

Evin, M., Callaghan, F., Fletcher, D.F., Grieve, S.M., 2019. Left ventricle vortex detection by

3D + t phase contrast MRI: a feasibility study. Comput. Methods Biomech. Biomed. Engin.

22, S71–S73. https://doi.org/10.1080/10255842.2020.1713483

Pierli C, Iadanza A, Del Pasqua A, Sinicropi G. Unusual localisation of a ventricular septal defect following blunt chest trauma. Heart. 2001;86:E6.

Pruitt CM, Titus MO. Ventricular septal defect secondary to a unique mechanism of blunt trauma: A case report. Pediatr Emerg Care. 2007;23:31–2.

Sawhney J, Patel PH, Blackwell RA. Early progression of an isolated ventricular septal defect after blunt trauma. J Trauma. 2008;64:218–20.

Zamani J, Amirghofran AA, Moaref AR, Afifi S, Rezaian GR. Posttraumatic coronary artery-right ventricular fistula with multiple ventricular septal defects. J Card Surg. 2010;25:670–1.