Electro-Fluid-Mechanics of the Heart - ICTAM 2020Electro-Fluid-Mechanics of the Heart R....

Electro-Fluid-MechanicsoftheHeart

R.Verzicco1,2,31UniversitàdiRomaTorVergata,Rome,IT,2UniversityofTwenteEnschede,NL,3GSSIL’Aquila,ITThehumanheartisahollowmuscularorganthatpumpsbloodthroughoutthebody,tothelungsandtoitsowntissue.Itdrivesthesystemic-,thepulmonary-andthecoronary-circulation,tobringoxygenand nutrients to every body cell and to remove the waste products. The heart achieves thesefundamentalgoalsbytwoparallelvolumetricpumps,therightandtheleft,whichbeatapproximately105 timesperday todelivera continuous flowrateofabout5 l/minwithanoutstandingreliability.Thisispossiblebecauseofthehighlycooperativeandinterconnecteddynamicsoftheheartinwhichevery element is key for the others. In a few words, each heart beat is triggered by specializedpacemakercellsthatgeneraterhythmicalelectricalimpulsespropagatingalongwelldefinedpathsandwithprecisetimingsthusstimulatingasequenceofcontractionswhichpumpthebloodfromatriatoventricles and eventually to the arteries. The resulting hemodynamics yields shear stresses andpressureloadsonthemyocardiumandonthevalves,whoseopening/closingensuresthecorrectflowdirection across heart chambers: only the synchronized and synergistic action of theelectrophysiology, mechanics of the myocardium and hemodynamics allows the heart of an adulthumantooperateonapowerofonly8W,lifelong.Suchaperfectandhighlysophisticatedmechanism,inwhichevenaminormalfunctioningimpairsitspumping efficiency, calls for a complete study considering thewhole organwith its interconnectedmulti-physicsdynamicsratherthanthesingleheartelementsseparately.Inthistalkwewillpresenttheresultsfromamulti-physicscomputationalmodelcapableoftacklingtheelectrophysiology,theelasto-mechanicsandthefluiddynamicsoftheheart,includingtheirmulti-way coupled interactions.Wewill showresults forphysiologic andpathologic conditionsaswell ascomparisonswithexperimentsandclinicaldata.

Figure 1: Isocontours of velocitymagnitude over aheartbeat for a `left heart’ made of atrium,ventricle, mitral and aortic valves, fibrous trine,ascendinganddescendingaorta.Thephasesof thecycle are indicated on the sketch of theelectrocardiographic signal at the centre. In theseresults, any dynamic feature comes as part of thesolutionandnothingisprescribed.(Adaptedfrom[2]).

References:[1] V. Spandan, V. Meschini, R. Ostilla-Mónico, D. Lohse, G. Querzoli, M.D. de Tullio, R. Verzicco, Aparallelinteractionpotentialapproachcoupledwiththeimmersedboundarymethodforfullyresolvedsimulationsofdeformableinterfacesandmembranes,J.ofComp.Phys.,348,567-590,(2017).[2] F. Viola, V. Meschini, R. Verzicco, A multi-way coupled computational model for the left-heart:Fluid-Structure-Electrophysiologyinteraction(FSEI),Eur.J.ofMech.B/Fluids,toappear,(2019).

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