Computational quantification of the cardiac energy consumption during intra-aortic balloon pumping using a cardiac electromechanics model

Abstract

To quantify the reduction in workload during intra-aortic balloon pump (IABP) therapy, indirect parameters are used, such as the mean arterial pressure during diastole, product of heart rate and peak systolic pressure, and pressure-volume area. Therefore, we investigated the cardiac energy consumption during IABP therapy using a cardiac electromechanics model. We incorporated an IABP function into a previously developed electromechanical model of the ventricle with a lumped model of the circulatory system and investigated the cardiac energy consumption at different IABP inflation volumes. When the IABP was used at inflation level 5, the cardiac output and stroke volume increased 11%, the ejection fraction increased 21%, the stroke work decreased 1%, the mean arterial pressure increased 10%, and the ATP consumption decreased 12%. These results show that although the ATP consumption is decreased significantly, stroke work is decreased only slightly, which indicates that the IABP helps the failed ventricle to pump blood efficiently.

Keywords: ATP Consumption; Cardiac Electromechanics Model; Intra-Aortic Balloon Pump; Stroke Work.

Fig. 1

Schematic diagram of the finite-element ventricular electromechanical model coupled with the circulatory model (A). P_RV, RV pressure; V_RV, RV volume; P_LV, LV pressure; V_LV, LV volume; R_PA, pulmonary artery resistance; C_PA, pulmonary artery compliance; R_PV, pulmonary vein resistance; C_PV, pulmonary vein compliance; R_MI, mitral valve resistance; C_LA, left atrium compliance; R_AO, aortic valve resistance; R_SA, systemic artery resistance, R_SA,IABP, the resistance of IABP-implanted systemic arteries; C_SA, systemic artery compliance; R_SV, systemic vein resistance; C_SV, systemic vein compliance; R_TR, tricuspid valve resistance; C_RA, right atrium compliance; and R_PU, pulmonary valve resistance. C_SA,IABP is calculated as the product of C_SA and a scale factor for the IABP effects.

Fig. 2

Electrical activation time mapped to mechanical component of ventricular computational mesh. The activation time is defined as the instant at which transmembrane voltage exceeds 0 mV. EAT indicates electrical activation time.

Fig. 3

Simulated pressure waveform in the LV and systemic artery. HF without IABP support (A), and HF with the IABP operating at levels 1 (B), 2 (C), 3 (D), 4 (E), and 5 (F).

Fig. 4

Transmural distribution of the ATP consumption rate. Heart failure ventricles without IABP support (A) and with IABP support at level 5 (B).

Fig. 5

Transmural distribution of the mechanical strain. Heart failure ventricles without IABP support (A) and with IABP support at level 5 (B).

Fig. 6

The pressure-volume curves for the six cases studied. Heart failure without IABP therapy, and HF with the IABP at levels 1 to 5.