ARTICLE IN PRESS JID: JJBE [m5G;February 19, 2016;18:3] Medical Engineering and Physics 000 (2016) 1–8 Contents lists available at ScienceDirect Medical Engineering and Physics journal homepage: www.elsevier.com/locate/medengphy In vitro assessment of mitral valve function in cyclically pressurized porcine hearts Riccardo Vismara a,b,∗ , Alberto M. Leopaldi c , Marco Piola a , Chiara Asselta a , Massimo Lemma b,d , Carlo Antona b,d,e , Alberto Redaelli a,b , Frans van de Vosse f , Marcel Rutten f , Gianfranco B. Fiore a,b a Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy b Forcardiolab, Fondazione per la ricerca in Cardiochirurgia ONLUS, Milan, Italy c Life Tec Group, Eindhoven, The Netherlands d Cardiovascular Surgery Department, ‘Luigi Sacco’ University general Hospital, Milan, Italy e Università degli Studi di Milano, Milan, Italy f Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands a r t i c l e i n f o Article history: Received 13 March 2015 Revised 22 December 2015 Accepted 31 January 2016 Available online xxx Keywords: In vitro Circulatory mock loops Mitral valve a b s t r a c t Recent approaches to the in vitro experimental study of cardiac fluid mechanics involve the use of whole biological structures to investigate in the lab novel therapeutic approaches for the treatment of heart pathologies. To enhance reliability and repeatability, the influence of the actuation strategy of the exper- imental apparatuses on the biomechanics of biological structures needs to be assessed. Using echography and intracardiac high-speed imaging, we compared the mitral valve (MV) anatomo- functional features (coaptation areas/lengths, papillary muscles-valvular plane distances) in two passive- beating-heart mock loops with internal (IPML) or external (EPML) pressurization of the ventricular cham- ber. Both apparatuses showed fluid dynamic conditions that closely resembled the physiology. The MVs ana- lyzed in the EPML presented coaptation areas and lengths that were systematically higher, and exhibited greater variability from early-to peak-systole, as compared to those in the IPML. Moreover, in the EPML, the MV leaflets exhibited a convexity with high curvature toward the atrium. With the IPML, MV coapta- tion lengths ranged similar to available clinical data and the papillary muscles-valve plane distances were more stable throughout systole. In conclusion, both the apparatuses allow for reproducing in vitro the left heart hemodynamics, in terms of flow rates and pressures, with proper mitral valve continence. Results suggest that the IPML is more suitable for replicating the physiological MV functioning, while the EPML may have more potential as a model for the study of MV pathologies. © 2016 IPEM. Published by Elsevier Ltd. All rights reserved. 1. Introduction Novel approaches to cardiac valve pathologies such as repar- ative valve surgery, sutureless bioprostheses, transcatheter proce- dures and minimally invasive implantable devices, have recently contributed to notable transformations in the clinical practice. In- deed, in contrast with former-generation therapies, these new ap- proaches rely on the idea that a reduced invasiveness and a bet- ter preservation of the native heart structures are key features for ∗ Corresponding author. Tel.: +39 0223994142; fax: +39 0223993360. E-mail address: riccardo.vismara@polimi.it (R. Vismara). an enhanced clinical outcome. This trend is well exemplified by the evolution of prosthetic heart valves from the mechanical valve concept, which aimed at restoring the mere one-way function of the substituted valve, to the current state-of-the-art bioprostheses, whose design is carried out taking into consideration the complex interplay with the surrounding native structures. Along with the evolution of the clinical practice, the experi- mental methods for the biomechanical and hemodynamic study of cardiac devices and therapies have undergone a similar progress. In the past, mock loops were commonly designed as wholly artificial devices, capable of inducing natural-like hemodynamics through the tested mechanical valve. Nowadays, novel devices and procedures involve much more demanding requirements, since http://dx.doi.org/10.1016/j.medengphy.2016.01.007 1350-4533/© 2016 IPEM. Published by Elsevier Ltd. All rights reserved. Please cite this article as: R. Vismara et al., In vitro assessment of mitral valve function in cyclically pressurized porcine hearts, Medical Engineering and Physics (2016), http://dx.doi.org/10.1016/j.medengphy.2016.01.007