Computer-controlledin vitro model of the human left heart

Abstract

The decision for surgical intervention in the treatment of stenosis and for regurgitation of the mitral valve demands an objective and quantitative evaluation of the severity of mitral valve disease. The availability of ultrasound techniques capable of analysing flow velocities across valves and to produce representative images of valve orifices has increased the interest in the hydraulics of cardiac valves. To isolate and study the determinants of transmitral flow, an in vitro model of the human left heart was built. From the model it is possible to differentiate the influence of the different determinants of left heart performance on transmitral flow: preload, compliance of the left atrium and ventricle, peripheral resistance (afterload) and heart rate. The mechanical part of the model consists of a reservoir connected to an elastic closed circuit (Latex pulmonary veins, left atrium, left ventricle and aortic arch) with replaceable mitral and aortic valves. The electronic part of the model drives and controls the hydraulic part, allowing the independent regulation and monitoring of left atrial and left ventricular pressures p, volumes V and 'pV-loops' throughout the cardiac cycle at different cardiac rhythms. Left atrial filling pressure and aortic resistance are variable in a controlled fashion. Echo-Doppler study of the mitral valve and the transmitral valve flow is possible both from an atrial and a ventricular window in the model. This technical note describes the model.

A Novel Interface for Hybrid Mock Circulations to Evaluate Ventricular Assist Devices

“…The controller input is the deviation of the measured fluid level 2 Blood pump speed controller is not described in this paper.…”

“…This paper focuses on mock circulations. Conventional mock circulation models are widely used, featuring various levels of complexity, physiological behavior, and development costs [2]- [6]. In the last decade, several research groups have started including numerical models in their mock circulations, which yielded semihybrid [7]- [14] or full-hybrid [15]- [17] mock circulations.…”

Influence of zero flow pressure on fractional flow reserve

“…Pulsatile flow is generated by a model of the human left heart (d), which basically consists of two (instead of four) pulmonary veins (c), the left atrium and ventricle and the aortic arch (Verdonck et al 1992). The elastic properties of the aorta are simulated by installing an air chamber (Windkessel element) (e).…”

A novel hydraulic thick-walled phantom for the assessment of left ventricular function

“…As such, biomechanical models of the human heart ideally need to account for realistic wall deformation. In previous experimental model investigations (Verdonck, 1992), wall deformation has generally been studied using thin-walled passive models, in which the effect of active muscle contraction and, hence, natural wall deformation cannot be simulated. The aims of this study were, therefore, to (1) construct an experimental hydraulic model of the LV wall in which the wall deformation can be actively controlled, and (2) to validate this thick-walled LV model by measuring aortic pressure and flow and LV pressure.…”