Mock Circulatory System of the Fontan Circulation to Study Respiration Effects on Venous Flow Behavior

Abstract

We describe an in vitro model of the Fontan circulation with respiration to study subdiaphragmatic venous flow behavior. The venous and arterial connections of a total cavopulmonary connection (TCPC) test section were coupled with a physical lumped parameter (LP) model of the circulation. Intrathoracic and subdiaphragmatic pressure changes associated with normal breathing were applied. This system was tuned for two patients (5 years, 0.67 m2; 10 years, 1.2 m2) to physiological values. System function was verified by comparison to the analytical model on which it was based and by consistency with published clinical measurements. Overall, subdiaphragmatic venous flow was influenced by respiration. Flow within the arteries and veins increased during inspiration but decreased during expiration with retrograde flow in the inferior venous territories. System pressures and flows showed close agreement with the analytical LP model (p < 0.05). The ratio of the flow rates occurring during inspiration to expiration were within the clinical range of values reported elsewhere. The approach used to setup and control the model was effective and provided reasonable comparisons with clinical data.

In Vitro Assessment of the Assisted Bidirectional Glenn Procedure for Stage One Single Ventricle Repair

“…For each circulation, the system was tuned by scaling the several resistance and compliance element values according to scaling laws based on body surface area (BSA) or by applying measured clinical values. 13,29 As pulmonary vascular resistance (PVR) has a significant effect on hemodynamics and postoperative recovery of infants after cardiac operations, 21,26 both high PVR and low PVR cases were tested here replicating the numerical simulations reported previously. 19 A pediatric ventricular-assist device or VAD (Excor Ò , 25 ml Berlin Heart, Berlin, Germany) developed the pulsatile aortic pressure and cardiac output for the single ventricle system.…”

“…1 was reduced from its host numerical model by impedance matching, an approach to MCS design described and validated previously. 3, 29 The physical system and models used are shown in Fig. 2.…”

“…Multi-scale simulations consider the local hemodynamics in the context of the entire circulation by providing appropriate boundary conditions to the anastomosis sites and have shown themselves to be consistent with clinical measurements (e.g., Refs. 3,4,13,14,16,19,20,29).…”

3D Printing Cardiovascular Anatomy: A Single-Centre Experience

“…the Glenn procedure and the total cavopulmonary connect (or Fontan completion) [22]. A system incorporating a patient-specific 3D-printed Fontan model has indeed been realised [23]. Figure 5.…”

“…In the second case, the MCL can be modified to be compatible with different visualisation techniques, e.g. particle image velocimetry [23] or magnetic resonance imaging, thereby generating detailed visualisation data. A case study of CHD, namely transposition of the great arteries (TGA) repaired with the arterial switch procedure (ASO), was modelled for both purposes [26].…”